DESCRIPTION
BRAKE CYLINDER DEVICE AND DISC BRAKE DEVICE
Technical field
[0001] The present invention relates to a brake cylinder device including a clearance
adjustment mechanism for automatically adjusting a clearance up to a brake
operating position in a brake-released state, and a disc brake device including the
brake cylinder device.
Background Art
[0002] A known example of the brake cylinder device including a clearance
adjustment mechanism for automatically adjusting a clearance up to a brake
operating position (position where braking force can be generated) in a brake-released
state is disclosed in Patent Document 1. The brake cylinder device disclosed in
Patent Document 1 is provided with a push rod having an uneven surface formed in its
exterior and a guide member that is movable together with the push rod. Also, an
O-ring for engaging with the uneven surface is disposed in a space between the guide
member and the push rod, and a clearance up to a brake operating position in a
brake-released state is automatically adjusted by the O-ring climbing over the
protrusions of the uneven surface when a force of a predetermined value or greater
acts on the guide member, Thus, the clearance adjustment mechanism is configured
by the uneven surface and the O_ring engaging therewith, and it is therefore possible,
with a simple configuration, to achieve a brake cylinder device including a clearance
adjustment mechanism for which sliding resistance can be readily adjusted and
managed.

[0003] Meanwhile, a known example of a brake cylinder device including a clearance
adjustment mechanism that does not use an O-ring unlike the above-described device
is disclosed in Patent Document 2. The clearance adjustment mechanism of the
brake cylinder device disclosed in Patent Document 2 is provided with a cylindrical
sheath rod that is rotatably supported to a piston via a bearing and that includes a
linear key groove and a spiral key groove formed in its outer circumference, and a push
rod attached to a push rod receiver threadably engaging with the inner circumference
of the sheath rod. Further, the teeth of the gear of a ratchet mechanism whose
direction of rotation is restricted by engaging with a pawl are configured to be fitted
into the key grooves of the sheath rod. Then, when the stroke of the piston is greater
than or equal to a predetermined stroke during the breaking operation, the position of
engagement between the pawl and the ratchet gear is displaced. Thereby, a clearance
up to a brake operating position in the brake-released state is automatically adjusted.
Citation List
Patent Document
[0004] Patent Document 1: JP 2007-131203A
Patent Document 2: JP 61-59158U
Disclosure of the Invention
Problem To be Solved by the Invention
[0005] The above-described clearance adjustment mechanism of the brake cylinder
device disclosed in Patent Document 1 uses the elastic deformation of the O-ring, and
thus is likely to be affected by the surrounding environment such as temperature and
humidity at the time of operation of the clearance adjustment mechanism. For this

reason, it is necessary to construct the clearance adjustment mechanism using an
Oring formed of a special material that is less likely to be affected by the surrounding
environment such as temperature and humidity, which results in a cost increase. On
the other hand, the clearance adjustment mechanism of the brake cylinder device
disclosed in Patent Document 2 does not use an Oring, and therefore requires very
little cost to suppress the influence of the surrounding environment such as
temperature and humidity. In the case of the clearance adjustment mechanism
disclosed in Patent Document 2, however, it is necessary to provide a bearing for
rotatably supporting the sheath rod on the rear side, i.e., the piston side, which is
opposite to the brake output portion disposed on the front side, i.e., the tip side of the
push rod. This results in a limiting factor in reducing the radial dimension on the
rear side of the cylinder body in which the piston is disposed.
[0006] In view of the foregoing circumstances, it is an object of the present invention
to provide a brake cylinder device including a clearance adjustment mechanism for
automatically adjusting a clearance up to a brake operating position in a
brake-released state at low cost, wherein the brake cylinder device is less likely to be
affected by the surrounding environment such as temperature and humidity and can
also achieve a reduction in the radial dimension of the cylinder body. It is also an
object of the invention to provide a disc brake device including the brake cylinder
device.
Means for Solving the Problems
[0007] A brake cylinder device according to a first aspect of the present invention for
achieving the above-stated objects is a brake cylinder device comprising: a cylinder
body having a hollow interior; a piston that defines a pressure chamber inside the

cylinder body and to which a biasing force generated by a piston spring is transmitted,
the piston moving relative to the cylinder body against the biasing force of the piston
spring by supply of pressure fluid to the pressure chamber; a brake output portion that
is provided so as to be movable together with the piston or provided so as to be
movable via a force amplifying mechanism for amplifying a force generated in the
piston as a result of movement of the piston, the brake output portion being movable in
a braking direction in which it projects from the cylinder body and an anti-braking
direction in which it approaches the cylinder body. Further, the break cylinder device
according to the first aspect of the invention also comprises: a threaded shaft that is
connected to the brake output portion and has a thread formed on an outer
circumference thereof; a guide tube that is attached to the piston or the force
amplifying mechanism and accommodates the threaded shaft thereinside; a pusher
spring disposed so as to be capable of biasing the threaded shaft toward the braking
direction to the guide tube or the piston; a clutch nut for threadably engaging with a
tip of the threaded shaft disposed on the brake output portion side with respect to the
cylinder body; a front stopper disposed so as to be capable of coming into contact with
the clutch nut on a front side, which is the brake output portion side with respect to
the clutch nut such that a movement of the clutch nut with respect to the guide tube is
restricted, and biasing the clutch nut and the threaded shaft in the antr-braking
direction together with a movement of the guide tube in the anti-braking direction; a
first clutch disposed so as to be capable of coming into contact with the clutch nut via a
predetermined interval from the front stopper on a rear side, which is a side opposite
to the brake output portion side with respect to the clutch nut; an adjustment stopper
that is disposed so as to be movable relative to the clutch nut and the guide tube along
the axial direction of the threaded shaft and whose movable range is restricted with

respect to the cylinder body; a second clutch to which the adjustment stopper is fixed,
and that is disposed so as to be capable of coming into contact with the clutch nut on
the rear side; and an adjustment spring that is in contact with or connected to the
adjustment stopper or the second clutch at a first end thereof and is capable of biasing
the clutch nut toward the anti-braking direction.
[0008] According to this aspect of the invention, during the braking operation, by
supplying the pressure fluid to the pressure chamber, the piston moves against the
biasing force of the piston spring, which causes the brake output portion to move in the
braking direction via the guide tube, the first clutch, the clutch nut, and the threaded
shaft, and thereby braking force is generated. Note that in the case where the force
amplifying mechanism is provided, the force from the piston is transmitted via the
force amplifying mechanism. On the other hand, by discharging the pressure fluid
from the pressure chamber, the piston moves in the opposite direction by the biasing
force of the piston spring, which causes the brake output portion to move in the
anti-braking direction via the guide tube, the front stopper, the clutch nut, and the
threaded shaft, and thereby the brake is released. In the case where the clearance up
to a brake operating position in the brake-released state is increased, for example, as a
result of wear of the brake pads, the above-described clearance is automatically
adjusted by the clearance adjustment mechanism composed of the clutch nut, the first
and second clutches, the threaded shaft, the guide tube, the pusher spring, the front
stopper, the adjustment stopper, and the adjustment spring.
[0009] In the case where the clearance adjustment is performed, first, during the
braking operation, the range of movement of the adjustment stopper is restricted, and
thereby a force capable of biasing the clutch nut in the anti-braking direction is
accumulated in the adjustment spring as the accumulated force of the adjustment

spring. Further, at this time, the contact of the clutch nut with the second clutch to
which the adjustment stopper is fixed is released, and a clearance is formed between
the second clutch and the clutch nut. Since the threaded shaft is biased in the
braking direction by the pusher spring, when the guide tube starts moving in the
anti-braking direction during the brake releasing operation, the threaded shaft and
the brake output portion do not move in the anti-braking direction, resulting in a state
in which the clutch nut is biased in the anti-braking direction by the accumulated force
of the adjustment spring. At this time, a state occurs in which the contact of the
clutch nut with the first clutch is released and the clutch nut is not in contact with the
front stopper either, and further, because the clutch nut is not in contact with the
second clutch either, the clutch nut becomes rotatable with respect to the threaded
shaft in this state. Then, the clutch nut rotates with respect to the threaded shaft by
the accumulated force of the adjustment spring so as to move in the anti-braking
direction. Thereafter, the clearance between the clutch nut and the second clutch is
lost and the clutch nut and the second clutch come in contact with each other, which
makes the clutch nut unrotatable. As a result of the movement of the guide tube in
the anti-braking direction, the brake output portion moves in the anti-braking
direction together with the front stopper, the clutch nut, and the threaded shaft, and
thereby the brake is released. Thus, the clutch nut moves relative to the threaded
shaft in the anti-braking direction in the middle of the brake releasing operation, and
therefore, the brake releasing operation ends in a state in which the position of the
threaded shaft has moved further in the braking direction than in the state before the
brake releasing operation. That is, a transition is made to a state in which the
threaded shaft and the brake output portion have moved to positions projecting with
respect to the cylinder body, as compared to the state before the braking operation.

Consequently, the clearance up to the brake operating position in the brake-released
state is automatically adjusted.
[0010] As described above, according to the present invention, the clearance
adjustment mechanism includes the clutch nut, the first and second clutches, the
threaded shaft, the guide tube, the pusher spring, the front stopper, the adjustment
stopper, and the adjustment spring. Accordingly, the clearance adjustment is not
performed using elastic deformation of rubber or the like, and it is therefore possible to
achieve a configuration that is less likely to be affected by the surrounding
environment such as temperature and humidity at low cost. Also, it is not necessary
to provide a bearing in the structure for attaching the guide tube to the piston or the
force amplifying mechanism, which makes it possible to reduce the radial dimension of
the cylinder body on the rear side.
[0011] Therefore, according to the present invention, it is possible to provide a brake
cylinder device including a clearance adjustment mechanism for automatically
adjusting a clearance up to a brake operating position in a brake-released state at low
cost, wherein the brake cylinder device is less likely to be affected by the surrounding
environment such as temperature and humidity and can also achieve a reduction in
the radial dimension of the cylinder body.
[0012] Note that with the brake cylinder device according to the present invention, in
a state in which the automatic clearance adjustment operation by the clearance
adjustment mechanism is not performed, the state in which the second clutch and the
clutch nut are in contact with each other is maintained regardless of whether it is
during the braking operation or when the brake is released, and the second clutch and
the clutch nut are prevented from being spaced apart from each other. In other words,
in the state in which the clearance adjustment operation is not performed, the clutch

nut is biased in the anti-braking direction by the adjustment spring in contact with, or
connected to the second clutch at one end, and thereby the state in which the second
clutch and the clutch nut are in contact with each other is maintained. Consequently,
the clutch nut is prevented from rotating with respect to the threaded shaft at any
time other than during the clearance adjustment operation, and the position of the
clutch nut with respect to the threaded shaft is prevented from shifting due to
vibration or the like.
[0013] According to a brake cylinder device of a second aspect of the present
invention, in the brake cylinder device of the first aspect, the threaded shaft has a
hollow interior formed so as to be open toward a side opposite to the brake output
portion, and the pusher spring biases the clutch nut threadably engaged with the
threaded shaft toward the front stopper by biasing the threaded shaft from inside.
[0014] According to this aspect of the invention, the pusher spring that biases the
threaded shaft is disposed inside the threaded shaft having a hollow structure, and is
configured to bias the clutch nut threadably engaged with the threaded shaft toward
the front stopper. Accordingly, the pusher spring can be disposed by efficiently using
the space in the brake cylinder device. This can increase the space efficiency in the
brake cylinder device, which makes it possible to realize a further size reduction.
[0015] According to a brake cylinder device of a third aspect of the present invention,
the brake cylinder device of the second aspect further includes a pusher spring guide
that is formed as a shaft-like portion provided so as to be movable together with the
guide tube and is inserted inside the pusher spring provided as a coil-shaped spring to
restrict deformation of the pusher spring in the buckling direction, wherein the pusher
spring guide is disposed such that a tip thereof is slidable on the inside of the threaded
shaft.

[0016] According to this aspect of the invention, the pusher spring guide is provided
that extends inside the coil-shaped pusher spring and restricts the deformation of the
pusher spring in the buckling direction. Accordingly, the dimension of the clearance
to be adjusted by the clearance adjustment mechanism is increased, and therefore, the
buckling of the pusher spring can be efficiently prevented even if a long pusher spring
is required. Further, the pusher spring guide provided so as to be movable together
with the guide tube is disposed such that its tip is slidable on the inside of the threaded
shaft. Accordingly, it is possible, with a simple configuration of providing the
shaft-like pusher spring guide, to readily achieve a structure that maintains the
positional relationship between the threaded shaft and the piston such that they are
displaced coaxially.
[0017] According to a brake cylinder device of a fourth aspect of the present invention,
in the brake cylinder device of any one of the first to third aspects, the front stopper
and the first clutch are provided as separate unitary members, and are each fixed to
the guide tube.
[0018] According to this aspect of the invention, the front stopper and the first clutch
are provided as separate unitary members and are separately fixed to the guide tube.
Accordingly, it is not necessary to provide each of the front stopper and the first
clutches disposed at the front and the rear, respectively, of the clutch nut as a divided
structure and perform coupling with additional coupling means. Likewise, it is not
necessary to provide the clutch nut at the front and the rear of which the front stopper
and the first clutch are disposed as a divided structure and perform coupling with
additional coupling means. This can simplify the configuration for the front stopper,
the first clutch, and the clutch nut, and consequently, the size and the weight of the
brake cylinder device as a whole can be reduced. Furthermore, due to the

configuration in which the front stopper and the first clutch are separate unitary
members and are fixed to the guide tube, it is possible to set the dimensional
configuration such that the inner circumferences of the front stopper and the first
clutch are located closer to the outer circumference of the threaded shaft, which makes
it possible to realize a further size reduction for the brake cylinder device.
[0019] According to a brake cylinder device of a fifth aspect of the present invention,
in the brake cylinder device of the fourth aspect, at least one of the front stopper and
the first clutch is fixed to an inner circumference of the guide tube by threaded
coupling.
[0020] According to this aspect of the invention, at least one of the front stopper and
the first clutch provided as separate unitary members is fixed to the inner
circumference of the guide tube by threaded coupling. Accordingly, the front stopper
and the first clutch fixed to the guide tube by threaded coupling can be readily replaced
at the time of maintenance, which makes it possible to increase the ease of
maintenance.
[0021] According to a brake cylinder device of a sixth aspect of the present invention,
the brake cylinder device of any one of the first to fifth aspects further includes an
adjustment sleeve that is provided as a tubular member disposed around the threaded
shaft and having flexibility, and is biased toward the anti-bralring direction by a second
end of the adjustment spring whose first end is in contact with or connected to the
adjustment stopper or the second clutch, wherein the clutch nut and the adjustment
sleeve are configured integrally by engagement of an engaging portion formed on the
adjustment sleeve with an engaged portion formed on the clutch nut.
[0022] According to this aspect of the invention, the adjustment spring is disposed
between the tubular adjustment sleeve disposed around the threaded shaft and the

adjustment stopper or the second clutch, and a force for moving the clutch nut relative
to the threaded shaft in the anti-braking direction is accumulated during the clearance
adjustment operation along with the relative movement of the adjustment sleeve with
respect to the adjustment stopper and the second clutch. Also, the adjustment sleeve
is provided as a member having flexibility, and the adjustment sleeve and the clutch
nut are integrated by engagement of the engaging portion on the adjustment sleeve
side and the engaged portion on the clutch nut side. Accordingly, the engaging
portion can be engaged with the engaged portion by temporarily causing the
adjustment sleeve having flexibility to be elastically deformed, and therefore, the
adjustment sleeve and the clutch nut can be integrated without using any additional
fastening member. Thus, the structure for integrating the adjustment sleeve and the
clutch nut does not require any additional fastening member, and it is therefore
possible to achieve a further size reduction for the brake cylinder device.
[0023] According to a brake cylinder device of a seventh aspect of the present
invention, in the brake cylinder device of the sixth aspect, the engaging portion of the
adjustment sleeve engages from inside with the engaged portion formed on an inner
circumference of the clutch nut, and a clearance formed between an inner
circumference of the adjustment sleeve and the top of the ridge of the thread of the
threaded shaft has a smaller dimension in the radial direction of the adjustment sleeve
than a dimension, in the radial direction of the adjustment sleeve, of indented portions
of the engaging portion and the engaged portion that are fitted together.
[0024] According to this aspect of the invention, the adjustment sleeve is configured
to engage from inside of the clutch nut, and the dimension of the clearance between
the inner circumference of the adjustment sleeve and the top of the ridge of the thread
of the threaded shaft is set to be smaller than the radial dimension of the indented

portions of the engaging portion and the engaged portion that are fitted together (the
length, in the radial direction of the adjustment sleeve, of overlap of the indented
portions). Accordingly, the engaging portion of the adjustment sleeve having
flexibility is disposed between the clutch nut and the threaded shaft that are formed of
a metallic material, and, moreover, a dimensional relationship is set that can prevent
disengagement of the engaging portion of the adjustment sleeve from the engaged
portion caused by deformation toward the threaded shaft. This makes it possible to
firmly integrate the adjustment sleeve and the clutch nut even though the
engagement configuration is simple.
[0025] According to a brake cylinder device of an eighth aspect of the present
invention, in the brake cylinder device of the seventh aspect, the adjustment spring is
disposed so as to bias, at the second end thereof, a spring receiver attached to the
adjustment sleeve, and the spring receiver is disposed such that a clearance formed
between the outer circumference of the spring receiver and the inner circumference of
the guide tube has a dimension in the radial direction of the guide tube that is
substantially zero, or is disposed such that the outer circumference of the spring
receiver and the inner circumference of the guide tube are in sliding contact.
[0026] According to this aspect of the invention, the spring receiver is disposed such
that the clearance to the guide tube is substantially zero or is disposed so as to be in
sliding contact with the guide tube, and therefore, the threaded shaft can be supported
to the guide tube via the spring receiver, which makes it possible to prevent the
threaded shaft from being tilted with respect to the guide tube.
[0027] According to a brake cylinder device of a ninth aspect of the present invention,
in the brake cylinder device of the eighth aspect, the spring receiver includes a bearing.
[0028] According to this aspect of the invention, the second end of the adjustment

spring biases the adjustment sleeve via the bearing of the spring receiver, and
therefore, when the adjustment sleeve is biased by the accumulated force of the
adjustment spring, the clutch nut smoothly rotates together with the adjustment
sleeve and moves in the braking direction.
[0029] According to a brake cylinder device of a tenth aspect of the present invention,
the brake cylinder device of any one of the first to ninth aspects further includes a
spring stopper that restricts, to a predetermined amount or less, the amount of
displacement of the adjustment spring due to elastic deformation caused by relative
displacement of a second end of the adjustment spring with respect to the first end
thereof that is in contact with or connected to the adjustment stopper or the second
clutch.
[0030] According to this aspect of the invention, the spring stopper is provided that
restricts, to a predetermined amount or less, the amount of displacement of the
adjustment spring during the elastic deformation of the adjustment spring such that
the force for the clearance adjustment operation is accumulated. Accordingly, even if
the clearance adjustment operation is forcibly performed in an operation that does not
generate braking force with a conventional clearance adjustment operation (in the case
of applying the brake cylinder device to a disc brake, an operation that does not cause
the brake pads to come into contact with the disc with a conventional clearance
adjustment operation: note that the clearance adjustment is performed using the force
generated by the brake pads coming into contact with the disc, and the clearance
adjustment cannot be performed without such contact), or in other words, in an
operation in the so-called idling state, the stroke of the adjustment spring is restricted
by the spring stopper. Accordingly, the adjustment spring will not be excessively
compressed or extended, and the clearance adjustment operation can be performed

forcibly even in the idling state. Note that the clearance is increased to exceed the
range where clearance adjustment is possible in order to facilitate the replacement of
the brake pads, and therefore, it has been hitherto necessary to manually perform the
clearance adjustment one by one when the replacement of the brake pads has been
performed. However, according to the present invention, as described above, the
adjustment spring will not be excessively compressed or extended, and the clearance
adjustment operation can be performed forcibly even in the idling state. Accordingly
by repeating operations corresponding to the braking operation and the brake
releasing operation multiple times for the entire vehicle or the entire group of vehicles
at once, the clearance is automatically adjusted in all brake cylinder devices. Thereby
when the brake pads have been replaced, it is possible to automatically perform the
clearance adjustment on all brake cylinder devices in a vehicle or a group of vehicles at
once, without the need to manually perform the clearance adjustment on brake
cylinder devices one by one. Accordingly, it is possible to significantly reduce the
number of steps and time and effort in the operation associated with the replacement
of brake pads, which makes it possible to considerably promote the efficiency.
[0031] According to a brake cylinder device of an eleventh aspect of the present
invention, in the brake cylinder device according to any one of the first to tenth aspects,
teeth capable of engaging the second clutch with the clutch nut are formed on at least
one of a surface of the second clutch that faces the clutch nut and a surface of the
clutch nut that feces the second clutch.
[0032] According to this aspect of the invention, in a state in which the clearance
adjustment is not being performed and the clutch nut and the second clutch are in
contact with each other, the clutch nut and the second clutch engage with each other
via the teeth formed on the mutually facing surfaces, and it is therefore possible to

reliably prevent the clutch nut from rotating with respect to the threaded shaft due to
vibrations or the like.
[0033] A brake cylinder device according to a twelfth aspect of the present invention
is the brake cylinder device of any one of the first to eleventh aspect of the invention,
wherein the threaded shaft is provided, at a tip thereof, with an operation engaging
portion capable of engaging with an operation tool, and is disposed such that the tip
passes through the brake output portion and feces outward, an engagement
mechanism is further provided that is disposed on the outer circumference of the tip of
the threaded shaft and engages the threaded shaft with the brake output portion, and
the engagement mechanism includes an outer circumferential engaging portion that
has engaging teeth capable of engaging with the brake output portion and is fixed to
the outer circumference of the threaded shaft, and an engaging spring that biases the
outer circumferential engaging portion toward the braking direction so as to engage
the engaging teeth with the brake output portion.
[0034] According to this aspect of the invention, an operation engaging portion is
provided at the tip disposed so as to pass through the brake output portion and face
outward, and the threaded shaft and the brake output portion are engaged with each
other by the engagement mechanism disposed on the outer circumference on the tip
side of the threaded shaft. Further, the engagement mechanism includes an
engagement spring and an outer circumferential engaging portion that has the
engaging teeth, and is configured to engage the threaded shaft with the brake output
portion via the engaging teeth by the engagement spring biasing the outer
circumferential engaging portion in the braking direction. Therefore, by releasing the
engagement of the outer circumferential engaging portion with the brake output
portion via the engaging teeth against the spring force of the engagement spring to

release the engagement of the threaded shaft with the brake output portion, and
further rotating the threaded shaft with an operation tool, the threaded shaft can be
rotated manually. Thus the positional relationship between the threaded shaft and
the clutch nut can be readily brought back into the initial state, which is the state
before the clearance adjustment is performed.
[0035] According to another aspect of the present invention, it is possible to configure
a disc brake device according to the invention including any one of the above described
brake cylinder devices. That is, according to a disc brake device of a thirteenth aspect
of the present invention includes the brake cylinder device of any one of the first to
twelfth aspects; and a caliper body that is equipped with the brake cylinder device and
is attached to a vehicle so as to be displaceable relative to the vehicle in the direction of
an axle, wherein operation of the brake cylinder device causes a disc on the axle side to
be sandwiched by a pair of brake pads attached to the caliper body, thereby generating
braking force.
[0036] According to this aspect of the invention, it is possible to provide a disc brake
device including a brake cylinder device provided with a clearance adjustment
mechanism for automatically adjusting a clearance up to a brake operating position in
a brake-released state at low cost, wherein the disc brake device is less likely to be
affected by the surrounding environment such as temperature and humidity and can
also achieve a reduction in the radial dimension of the cylinder body.
Effects of the Invention
[0037] According to the present invention, it is possible to provide a brake cylinder
device including a clearance adjustment mechanism for automatically adjusting a
clearance up to a brake operating position in a brake-released state at low cost,

wherein the brake cylinder device is less likely to be affected by the surrounding
environment such as temperature and humidity and can also achieve a reduction in
the radial dimension of the cylinder body. It is also possible to provide a disk brake
device including the brake cylinder device at low cost.
Brief Description of the Drawings
[0038] FIG. 1 is a side view of a disc brake device according to an embodiment of the
present invention.
FIG. 2 is a plan view of the disc brake device shown in FIG. 1.
FIG. 3 is a cross-sectional view of a brake cylinder device according to a first
embodiment of the present invention.
FIG. 4 is a diagram showing the tips of a brake output portion and a threaded
shaft of the brake cylinder device shown in FIG. 3, as viewed in the direction indicated
by the arrow C.
FIG. 5 is an enlarged cross-sectional view showing a part of the brake cylinder
device shown in FIG. 3 in enlargement.
FIG. 6 is a cross-sectional view of the brake cylinder device shown in FIG. 3
for illustrating a case where the brake cylinder device is operated without perforating
automatic clearance adjustment by a clearance adjustment mechanism.
FIG. 7 is a cross-sectional view of the brake cylinder device shown in FIG. 3
for illustrating a case where the brake cylinder device is operated without performing
automatic clearance adjustment by the clearance adjustment mechanism.
FIG. 8 is a cross-sectional view of the brake cylinder device shown in FIG. 3
for illustrating a case where the brake cylinder device is operated without performing
automatic clearance adjustment by the clearance adjustment mechanism.

FIG. 9 is a cross-sectional view of the brake cylinder device shown in FIG. 3
for illustrating a case where the brake cylinder device is operated without performing
automatic clearance adjustment by the clearance adjustment mechanism.
FIG. 10 is a cross-sectional view of the brake cylinder device shown in FIG. 3
for illustrating an operation in the case where automatic clearance adjustment by the
clearance adjustment mechanism is performed.
FIG. 11 is a cross-sectional view of the brake cylinder device shown in FIG. 3
for illustrating an operation in the case where automatic clearance adjustment by the
clearance adjustment mechanism is performed.
FIG. 12 is a cross-sectional view of the brake cylinder device shown in FIG. 3
for illustrating an operation in the case where automatic clearance adjustment by the
clearance adjustment mechanism is performed.
FIG. 13 is a cross-sectional view of the brake cylinder device shown in FIG. 3
for illustrating an operation in the case where automatic clearance adjustment by the
clearance adjustment mechanism is performed.
FIG. 14 is a cross-sectional view of the brake cylinder device shown in FIG. 3
for illustrating an operation in the case where automatic clearance adjustment by the
clearance adjustment mechanism is performed.
FIG. 15 is a cross'sectional view of the brake cylinder device shown in FIG. 3
for illustrating an operation in the case where automatic clearance adjustment by the
clearance adjustment mechanism is performed.
FIG. 16 is a cross-sectional view of the brake cylinder device shown in FIG. 3
for illustrating an operation in the case where automatic clearance adjustment by the
clearance adjustment mechanism is performed.
FIG. 17 is a cross-sectional view of the brake cylinder device shown in FIG. 3

for illustrating an operation in the case where automatic clearance adjustment by the
clearance adjustment mechanism is performed.
FIG. 18 is a cross-sectional view of the brake cylinder device shown in FIG. 3
for illustrating an operation in the case where a clearance adjustment operation is
performed in an idling state.
FIG. 19 is a cross-sectional view of the brake cylinder device shown in FIG. 3
for illustrating an operation in the case where a clearance adjustment operation is
performed in an idling state.
FIG. 20 is a cross-sectional view of the brake cylinder device shown in FIG. 3
for illustrating an operation in the case where a clearance adjustment operation is
performed in an idling state.
FIG. 21 is a cross-sectional view of the brake cylinder device shown in FIG. 3
for illustrating an operation in the case where a clearance adjustment operation is
performed in an idling state.
FIG. 22 is a cross-sectional view of a brake cylinder device according to a
second embodiment of the present invention.
Description of Embodiments
[0039] Hereinafter, embodiments of the present invention will be described with
reference to the drawings. Note that a description will now be given of a brake
cylinder device according to the present invention and a disc brake device including
the brake cylinder device, taking as an example, a case where they are used for a
railroad vehicle. Further, the accuracy of the attached drawings approximates to that
of engineering drawings.
[0040] First Embodiment

FIG. 1 is a side view of a disc brake device 1 according to an embodiment of
the present invention, as viewed in the axle direction. FIG. 2 is a plan view of the disc
brake device 1 shown in FIG. 1, as viewed from above. The disc brake device 1 shown
in FIGS. 1 and 2 includes a brake cylinder device 2, a caliper body 11 equipped with
the brake cylinder device 2 and attached to a vehicle body 100 so as to be displaceable
relative to the vehicle body 100 in the axle direction, a pair of back plates (12,12)
serving as brake shoe holding portions for respectively holding a pair of brake pads (13,
13) serving as brake shoes, and so forth.
[0041] The pair of brake pads (13,13) are attached to the caliper body 11 via the back
plates 12. Also, the disc brake device 1 is configured such that operation of the brake
cylinder device 2 causes the pair of brake pads (13,13) to sandwich a disc-like brake
disc 101 serving as a disc on the axle side that rotates in response to the rotation of a
wheel (not shown) of a railroad vehicle, thus generating a braking force. Note that
the brake disc 101 is formed in the shape of a disc having braking surfaces (101a,
101a) on both sides that are formed so as to be orthogonal to the rotational axis. Then,
operation of the brake cylinder device 2 causes the brake pads (13,13) to be pressed
against the braking surfaces (101a, 101a) so as to sandwich the brake disc 101 from
opposite sides from a direction substantially parallel to the direction of the rotational
axis of the brake disc 101.
[0042] The caliper body 11 includes a coupling member 14 and a pair of brake levers
(15,15). The coupling member 14 is attached via a swing pin 14a to a bracket 100a
fixed to the bottom face of the vehicle body 100 such that the coupling member 14 is
swingable about an axis parallel to the traveling direction of the vehicle. Also, the
pair of brake levers (15,15) are provided substantially symmetrical with respect to the
coupling member 14 so as to be swingable via a pair of fulcrum pins 15a. The fulcrum

pins 15a are provided so as to extend in a direction perpendicular to the axial direction
of the swing pin 14a, as viewed from the direction of the rotational axis of the disc
brake 101.
[0043] The pair of brake levers (15,15) are configured such that the brake cylinder
device 2 is attached thereto at one end via a cylinder support pin 15b and the end is
driven by the brake cylinder device 2. Also, the pair of back plates (12,12) for holding
the brake pads 13 are attached to the pair of brake levers (15, 15) via the fulcrum pins
15a at the other end, with respect to the end to which the brake cylinder device 2 is
attached. The back plates 12 are swingably attached to the brake levers 15 via
support pins 12a extending parallel to the fulcrum pins 15a.
[0044] In the above-described disc brake device 1, as will be described below, the
cylinder body 20 of the brake cylinder device 2 is attached to one of the brake levers 15,
whereas the brake output portion 21 is attached to the other brake lever 15, and an
operation of causing the brake output portion 21 to project or move in close to the
cylinder body 20 is performed by operation of the brake cylinder device 2. Thereby,
the disc brake device 1 is driven such that portions of the pair of brake levers (15,15)
that are in the vicinity of the cylinder support pins 15b project from or approach each
other.
[0045] By being driven in the above-described manner, the disc brake device 1
operates such that the pair of brake levers (15,15) operate with the fulcrum pins 15a
serving as the fulcrums and the brake disc 101 is sandwiched by the brake pads 13.
Also, at this time, in the pair of brake levers (15,15), one of the brake pads 13 that is
provided at one of the brake levers 15 first comes into contact with a braking surface
101a of the brake disc 101. Furthermore, the other brake lever 15 presses the other
brake pad 13 against a braking surface 101a of the brake disc 101, using a reaction

force applied from the brake pad 13 that has come into contact with the braking
surface 101a. Thereby, the brake disc 101 is sandwiched by the pair of brake pads (13,
13), and the frictional force generating between the brake pads (13,13) and the
braking surfaces (101a, 101a) brakes the rotation of the brake disc 101, thus braking
the rotation of the wheel of the railroad vehicle that is provided coaxially with the
brake disc 101.
[0046] Next, a brake cylinder device 2 according to a first embodiment of the present
invention will be described in detail. FIG. 3 is a cross-sectional view of the brake
cylinder device 2. Although the brake cylinder device 2 shown in FIG. 3 is configured
in the same manner as the brake cylinder device 2 shown in FIGS. 1 and 2, the outer
shape is partly modified. Opposite ends of the brake cylinder device 2 in the brake
operating direction are respectively connected to the cylinder support pins 15b. Also,
the brake cylinder device 2 includes a cylinder body 20, a brake output portion 21, a
piston 22, a piston spring 23, a threaded shaft 24, a guide tube 25, a pusher spring 26,
a clutch nut 27, a front stopper 28, a first clutch 29, adjustment stoppers 30, an
adjustment spring 31, a second clutch 32, an adjustment sleeve 33, a spring stopper 34,
a pusher spring guide 38, a bearing 40, an engagement mechanism 42, and so forth.
Of the above-described components, those other than the adjustment sleeve 33 are
formed of, for example, a metallic material such as an iron-based material, and the
adjustment sleeve 33 is formed o£ for example, a resin material. Note that FIG. 3
shows the outer shape, rather than the cross section, of the adjustment stoppers 30,
the pusher spring guide 38, and so forth.
[0047] The cylinder body 20 is composed of a first casing portion 35 and a second
casing portion 36, and has a hollow interior. Accommodated inside the cylinder body
20 are the piston 22, the piston spring 23, a part of the threaded shaft 24, the guide

tube 25, the pusher spring 26, the clutch nut 27, the front stopper 28, the first clutch
29, the adjustment stoppers 30, the adjustment spring 31, the second clutch 32, the
pusher spring guide 38, the adjustment sleeve 33, the spring stopper 34, and so forth.
The first casing portion 35 is substantially cup-shaped having a bottom, and the
second casing portion 36 is fixed with a bolt so as to close the opening side of the first
casing portion 35. Note that ends of the first casing portion 35 are connected to one of
the brake levers 15 with the cylinder support pins 15b. The second casing portion 36
is provided with a planar portion 36a formed in the shape of a flange so as to close the
first casing portion 35 and a tubular portion 36b formed in the shape of a tube
projecting perpendicularly to the planar portion 36a.
[0048] The piston 22 is disposed so as to partition the interior of the cylinder body 20,
and is provided so as to come into sliding contact with the inner circumferential face of
the first casing portion 35 in an airtight manner, and to be axially slidable with
respect to the first casing portion 35. The space defined by the piston 22 and the first
casing portion 35 forms a pressure chamber 37 inside the cylinder body 20.
Compressed air serving as pressure fluid is supplied to and discharged from the
pressure chamber 37 via communication passages (not shown).
[0049] The piston spring 23 is provided as a coil-shaped spring disposed inside the
cylinder body 20 on the side opposite to the pressure chamber 37 via the piston 22, and
is disposed between the piston 22 and the planar portion 36a of the second casing
portion 36. Thus a biasing force generated by the piston spring 23 is transmitted to
the piston 22 that defines the pressure chamber 37 inside the cylinder body 20. Also,
the piston spring 23 is disposed inside the cylinder body 20 so as to bias the piston 22
toward the pressure chamber 37 side. Then, by supplying compressed air to the
pressure chamber 37, the piston 22 moves relative to the cylinder body 20 against the

biasing force of the piston spring 23 and thus moves in a braking direction (the
direction indicated by the arrow A in FIG. 3). On the other hand, by discharging
compressed air from the pressure chamber 37, the piston 22 moves by the biasing force
of the piston spring 23 in an anti-braking direction (the direction indicated by the
arrow B in FIG. 3), which is the direction opposite to the braking direction.
[0050] The brake output portion 21 is connected to the piston 22 via the threaded
shaft 24, the guide tube 25, and so forth, which will be described below, and is provided
so as to be movable together with the piston 22. Thereby, the brake output portion 21
is provided so as to be movable in the braking direction (the direction of the arrow A) in
which it projects from the cylinder body 20 and the anti-braking direction (the
direction of the arrow B) in which it approaches the cylinder body 20. Also, the brake
output portion 21 is connected to the other brake lever 15 with the cylinder support
pins 15b. Note that a bellows structure disposed so as to cover the circumference of
the tubular portion 36b of the second casing portion 36 is provided as a protective cover
between the brake output portion 21 and the cylinder body 20.
[0051] The threaded shaft 24 is provided as a shaft-like member connected to the
brake output portion 21 and having a thread 24a formed on the outer circumference
thereof Also, the threaded shaft 24 has a hollow interior formed so as to be open
toward the side opposite to the brake output portion 21 (in this embodiment, the piston
22 side). That is, the interior hollow region of the threaded shaft 24 is provided as an
axial bore 24b extending axially and is open only on the side opposite to the brake
output portion 21.
[0052] FIG. 4 is a diagram showing the tips of the brake output portion 21 and the
threaded shaft 24, as viewed in the direction indicated by the arrow C in FIG. 3. As
shown in FIGS. 3 and 4, the threaded shaft 24 is provided, at its tip, a hexagon head

portion 24c serving as an operation engaging portion capable of engaging with an
operation tool (for example, a socket wrench). Note that this hexagon head portion
24c is formed as a portion having a hexagonal cylinder-shaped side (formed in the
same manner as a head of a hexagon head bolt, for example), and is fixed to the body
portion of the threaded shaft 24 so as to integrally rotate. Also, a through hole is
formed in the center portion of the brake output portion 21, and the tip of the threaded
shaft 24 is disposed so as to pass through the through hole of the brake output portion
21 and face outward. Note that the hexagon head portion 24 at the tip of the
threaded shaft 24 is disposed in a recess 21a that is formed so as to configure a part of
the through hole and be open on the end face of the brake output portion 21.
[0053] The engagement mechanism 42 is disposed on the outer circumference of the
tip of the threaded shaft 24, and is provided as a mechanism for engaging the threaded
shaft 24 with the brake output portion 21. The engagement mechanism 42 includes
an outer circumferential engaging portion 43 and an engaging spring 44. Further, in
the brake output portion 21, an engaging block 45 is provided in the center portion in
which the through hole is formed. This engaging block 45 is provided as a portion for
engaging with the engagement mechanism 42 in the brake output portion 21, and is
fixed to the body portion of the brake output portion 21 in the above-described through
hole. Also, in the engaging block 45, a hole in which the tip of the threaded shaft 24
passes through in a slidable state is formed so as to extend through the engaging block
45.
[0054] The outer circumferential engaging portion 43 of the engagement mechanism
42 includes a tubular fixed portion and an engaging teeth portion that are integrated
with each other. The tubular fixed portion is formed in a tubular shape and fixed on
the outer circumference of the threaded shaft 24. The engaging teeth portion is

provided at one end of the above-described tubular fixed portion and formed as a
portion expanding so as to form a flange shape or a portion expanding so as to to form
an umbrella-like shape having a large hole opening in the center, and has engaging
teeth 43a capable of engaging with the brake output portion 21. The engaging teeth
portion is disposed facing the engaging block 45 in the through hole in the center of the
brake output portion 21. Further, in the portion of the engaging block 45 in the brake
output portion 21 opposite the above-described engaging teeth portion, engaging teeth
45a for engaging with the engaging teeth 43a in the engaging teeth portion are
formed.
[0055] The engaging spring 44 in the engagement mechanism 42 is provided as a
coil-shaped spring, and is disposed in the through hole in the center of the brake
output portion 21 on the outer circumference of the tubular fixed portion of the outer
circumferential engaging portion 43. Further, the engaging spring 44 is disposed
such that one end thereof is in contact with the engaging teeth portion on the side
opposite to the side on which the engaging teeth 43a are formed. Also, the other end
of the engaging spring 44 is disposed so as to be in contact with a ring-shaped plate
member fixed to the brake output portion 21 to close a part of the opening of the
through hole in the center of the brake output portion 21 opposite to the recess 21a
side. Thereby, the engaging spring 44 is configured to bias the outer circumferential
engaging portion 43 toward a braking direction so as to engage the engaging teeth 43a
of the outer circumferential engaging portion 43 integrally fixed to the body portion of
the threaded shaft 24 with the engaging teeth 45a of the engaging block 45 in the
brake output portion 21. Thus, the threaded shaft 24 and the brake output portion 21
engage with each other via the engagement mechanism 42.
[0056] The guide tube 25 is formed as a cylindrical member, and is disposed such

that one end thereof is fixed and attached to the piston 22 and passes thorough the
tubular portion 36b of the second casing portion 36 of the cylinder body 20. Abase
plate 25a is attached to the end of the guide tube 25 that is fixed to the piston 22, and
the end feeing the brake output portion 21 is provided so as to be open. Also, the
threaded shaft 24 is accommodated in the interior space region of the guide tube 25.
[0057] Further, the surrounding wall of the guide tube 25 is provided, at a middle
position in the direction of the cylinder axis, a pair of slit apertures (25b, 25b) that are
formed therethrough in the form of slits. The pair of slit apertures (25b, 25b) are
provided so as to be disposed at positions along the diameter direction of the cylindrical
guide tube 25, and are formed as openings through which the adjustment stoppers 30,
which will be described below, pass from the inside toward the outside.
[0058] The pusher spring 26 is provided as a coil-shaped spring, and is disposed in
the axial bore 24b of the threaded shaft 24. Note that the axial bore 24b is provided
with a stepped portion whose diameter is reduced stepwise toward the inner side.
Also, the pusher spring 26 is provided as a compression spring, and is disposed such
that one end is in contact with the stepped portion of the axial bore 24b and the other
end is in contact with the base plate 25a of the guide tube 25. Thereby, the pusher
spring 26 is disposed so as to be capable of biasing the threaded shaft 24 to the guide
tube 25 from inside toward the braking direction.
[0059] The pusher spring guide 38 is formed as a shaft-like portion that is fixed to the
base plate 25a of the guide tube 25 and is provided so as to be movable together with
the guide tube 25. Also, the pusher spring guide 38 is disposed so as to project toward
the axial bore 24b of the threaded shaft 24, and is inserted inside the pusher spring 26.
Thereby, the pusher spring guide 38 is configured to restrict the deformation of the
pusher spring 26 in the buckling direction. Further, the pusher spring guide 38 is

inserted in a state in which the tip is in sliding contact with the inner bore portion with
a reduced diameter of the axial bore 24b of the threaded shaft 24. Thereby, the
pusher spring guide 38 is disposed such that the tip is slidable on the inside of the
threaded shaft 24.
[0060] FIG, 5 is an enlarged cross-sectional view showing a part of the brake cylinder
device 2 shown in FIG. 3 in enlargement. As shown in FLGS. 3 and 5, the clutch nut
27 is provided as a tubular member having an internally threaded portion formed on
its inner circumference, and is configured so as to threadably engage with the tip of the
threaded shaft 24 disposed on the brake output portion 21 side with respect to the
cylinder body 20. Further, on the outer circumference of the clutch nut 27 at an
axially middle position, a protrusion 27a is provided that is formed so as to extend
across the circumferential direction and project radially outward and that is capable of
coming into contact with the front stopper 28 and the first clutch 29, which will be
described below. Note that due to the provision of the clutch nut 27 as described
above, the pusher spring 26 is configured to bias the threaded shaft 24 from inside,
thereby biasing the clutch nut 27 threadably engaged with the threaded shaft 24
toward the front stopper 28.
[0061] The front stopper 28 is provided as a cylindrical member having an externally
threaded portion formed on its outer circumference and having a short axial length,
and is formed as a unitary member. Also, the front stopper 28 is threadably engaged,
at its externally threaded portion, with an internally threaded portion formed on the
inner circumference of the tip of the guide tube 25 that feces the brake output portion
21. That is, the front stopper 28 is fixed to the inner circumference of the guide tube
25 by threaded coupling. Note that a circumferentially extending groove is formed on
the inner circumference of the tip of the guide tube 25 on the brake output portion 21

side with respect to the front stopper 28. Then, a snap ring 41 for engaging with the
end of the front stopper 28 on the brake output portion 21 side is fitted into the groove,
thereby preventing withdrawal of the front stopper 28.
[0062] Further, the front stopper 28 is disposed outside and concentrically with
respect to the end of the clutch nut 27 on the brake output portion 21 side and the
threaded shaft 24 (such that the radial center positions coincide). Also, the front
stopper 28 is disposed so as to be capable of coming into contact with the protrusion
27a on the front side, which is the brake output portion 21 side with respect to the
clutch nut 27, so as to restrict movement of the clutch nut 27 relative to the guide tube
25. Thereby, the front stopper 28 is configured to be able to bias the clutch nut 27 and
the threaded shaft 24 threadably engaged with the clutch nut 27 in the anti-braking
direction together with the movement of the guide tube 25 in the anti-braking
direction.
[0063] The first clutch 29 is provided as a cylindrical member having a short axial
length, and is formed as a unitary member separate from the front stopper 28. Also,
the first clutch 29 is press-fitted inside the guide tube 25 and fixed to the guide tube 25.
Note that an end of the first clutch 29 is in contact and aligned with a step-shaped
portion formed on the inner circumference of the guide tube 25.
[0064] Further, the first clutch 29 is disposed outside and concentrically with respect
to the end of the clutch nut 27 on the piston 22 side and the threaded shaft 24 (such
that the radial center positions coincide). Also, the first clutch 29 is disposed so as to
be capable of coming into contact with the protrusion 27a of this clutch nut 27 with a
predetermined interval from the front stopper 28 from the rear side, which is the side
opposite to the brake output portion 21 side with respect to the clutch nut 27.
[0065] Further, the surface of the first clutch 29 that feces the clutch nut 27 is

provided as a tapered surface that is formed obliquely with respect to the axial
direction so as to form a part of a conic section, with the axial direction of the threaded
shaft 24 as the center line. The surface of the protrusion 27a of the clutch nut 27 that
feces the first clutch 29 is also provided as a tapered surface that is formed obliquely
with respect to the axial direction so as to form a part of a conic section, with the axial
direction of the threaded shaft 24 as the center line. Also, the above-described
surfaces of the first clutch 29 and the clutch nut 27 that face each other are formed as
surfaces that are inclined at substantially the same angle with respect to the axial
direction of the threaded shaft 24 and that come into contact with each other.
[0066] Two adjustment stoppers 30 are provided as a pair, and are fixed to the second
clutch 32, which will be described below, formed as a ring-shaped member or a
cylindrical member having a short axial length. Each adjustment stopper 30 is
provided as a block-shaped member protruding radially outward of the second clutch
32.
[0067] Also, the pair of adjustment stoppers (30, 30) are fixed to the second clutch 32,
which will be described below, so as to be disposed in positions along the diameter
direction of the guide tube 25 and the threaded shaft 24. Further, the pair of
adjustment stoppers (30, 30) are disposed so as to protrude to pass through a pair of
slit portions (25b, 25b) in the guide tube 25. Note that the tubular portion 36b of the
second casing portion 36 of the cylinder body 20 is provided, at positions along the
diameter direction of the tubular portion 36b, with a pair of stopper stroke restricting
portions (39, 39) that are provided as apertures formed therethrough in the form of
slits extending parallel to the axial direction of the threaded shaft 24. Also, the
projecting ends of the adjustment stoppers 30 are disposed so as to be movable along
the stopper stroke restricting portions 39, and also disposed so as to be capable of

coming into contact with the ends of the stopper stroke restricting portions 39 in the
braking direction and the ends thereof in the anti-braking direction.
[0068] By being provided in the above-described manner, the adjustment stoppers 30
are configured such that they are movable relative to the clutch nut 27 and the guide
tube 25 along the axial direction of the threaded shaft 24 and that their movable range
is restricted with respect to the cylinder body 20.
[0069] The second clutch 32 to which the adjustment stoppers 30 are fixed is formed
as a ring-shaped member or a cylindrical member having a short axial length, as
described above, and is disposed around the threaded shaft 24 and the adjustment
sleeve 33, which will be described below, and inside the guide tube 25. Further, the
second clutch 32 is disposed so as to be capable of coming into contact, at its end in the
braking direction, with the clutch nut 27 from the rear side, and is in contact, at its end
in the anti-braking direction, with the adjustment spring 31, which will be described
below.
[0070] Also, on an end surface of the second clutch 32 in the braking direction that
feces the clutch nut 27, teeth 32a are formed across the circumferential direction.
Meanwhile, on an end surface of the clutch nut 27 in the anti-braking direction that
feces the second clutch 32, teeth 27b are formed across the circumferential direction.
The teeth 32a on the second clutch 32 side and the teeth 27a on the clutch nut 27 side
are formed as teeth capable of engaging the second clutch 32 and the clutch nut 27.
[0071] The adjustment sleeve 33 is provided as a tubular member formed of resin
and thus having flexibility, and is disposed around the threaded shaft 24. Also, the
adjustment sleeve 33 is provided, on the outer circumference on its end side in the
braking direction, with an engaging portion 33a formed as an indented portion. Then,
the clutch nut 27 is provided, on the inner circumference on its end side in the

anti-braking direction, with an engaged portion 27c formed as an indented portion
that interfits with the indented portion of the engaging portion 33a. The adjustment
sleeve 33 and the clutch nut 27 are configured integrally by engagement of the
engaging portion 33a on the adjustment sleeve 33 side with the engaged portion 27c on
the clutch nut 27 side.
[0072] Note that the engaging portion 33a of the adjustment sleeve 33 is provided so
as to engage, from the inside, with the engaged portion 27c formed on the inner
circumference of the clutch nut 27. Also, the clearance formed between the inner
circumference of the adjustment sleeve 33 and the top of the ridge of the thread 24a of
the threaded shaft 24 is configured to have a smaller dimension in the radial direction
of the adjustment sleeve 33 than a dimension, in the radial direction of the adjustment
sleeve 33, of the indented portions of the engaging portion 33a and the engaged portion
27c that are fitted together (the length of overlap of the indented portion in the radial
direction of the adjustment sleeve 33).
[0073] The adjustment spring 31 is provided as a coil-shaped spring disposed around
the adjustment sleeve 33. Also, the adjustment spring 31 is disposed so as to be in
contact with (or to be connected to), at a first end, the end of the second clutch 32 in the
anti-braking direction, and to bias, at a second end, a spring receiver attached to the
end of the adjustment sleeve 33 in the anti-braking direction. Note that in the
present embodiment, the spring stopper 34 and a bearing 40 constitute the
above-described spring receiver. Thereby, the adjustment sleeve 33 is configured to be
biased in the anti-braking direction by the second end of the adjustment spring 31
whose first end is in contact with the second clutch 32. Also, the adjustment spring
31 is configured to be capable of biasing, in the anti-braking direction, the clutch nut
27 engaged and thus integrated with the adjustment sleeve 33.

[0074] The bearing 40 included in the above-described spring receiver is disposed
between the outer circumference of the adjustment sleeve 33 and the inner
circumference of the guide tube 35, and engages with a flange'shaped projection
formed around the outer circumference of the end of the adjustment sleeve 33 in the
anti-braking direction across the circumferential direction, thereby being attached to
the adjustment sleeve 33. Also, the bearing 40 included in the above spring receiver
is disposed such that the clearance formed between the outer circumference of the
bearing 40 (Le., the outer circumference of the spring receiver) and the inner
circumference of the guide tube 25 has a dimension in the radial direction of the guide
tube 25 that is substantially zero. Note that the spring receiver including the bearing
40 may be disposed such that the outer circumference of the bearing 40 (Le., the outer
circumference of the spring receiver) and the inner circumference of the guide tube 25
are in sliding contact.
[0075] The spring stopper 34 is provided as a tubular member disposed around the
end side of the adjustment sleeve 33 in the anti-braking direction. Also, a
flange-shaped portion is formed at the end of the spring stopper 34 in the anti-braking
direction, and the spring stopper 34 is in contact with the bearing 40 at the end face of
this flange-shaped portion in the anti-braking direction. Further, the spring stopper
34 is in contact with the second end of the adjustment spring 31 (the end in the
anti-braking direction) at the end face of the above-described flange-shaped portion in
the braking direction. Note that the bearing 40 is disposed between the spring
stopper 34 and the adjustment sleeve 33, and therefore the adjustment sleeve 33 is
configured to be rotatable with respect to the spring stopper 34.
[0076] The end of the tubular portion of the spring stopper 34 in the braking
direction feces the end of the second clutch 32 in the anti-braking direction via a gap.

Also, the end of the tubular portion of the spring stopper 34 in the braking direction is
disposed so as to come into contact with the end of the second clutch 32 in the
anti-braking direction when the adjustment spring 31 is significantly compressed.
Thereby, the spring stopper 34 is configured to restrict, to a predetennined amount or
less, the amount of displacement of the adjustment spring 31 due to the elastic
deformation caused by the second end of the adjustment spring 31 being relatively
displaced with respect to the first end thereof in contact with the adjustment stoppers
30.
[0077] Note that even if the biasing force of the adjustment spring 31 becomes large
as a result of accumulation of the force, the fiictional force resulting from this biasing
force will not impede the rotation of the clutch nut 27 engaged and integrated with the
adjustment sleeve 33 because the above-described components of the spring receiver
includes the bearing 40, in contrast to a configuration in which grease is simply
applied to a disc-like member without the use of a bearing. That is, due to the
provision of the bearing 40, the above-described biasing force hardly affects the
direction of rotation of the adjustment sleeve 33 and the clutch nut 27 that rotate
together with the bearing 40, and therefore, the clearance adjustment can be
performed reliably, as will be described below. Note that the bearing 40 may be a
rolling bearing or a sliding bearing, or may be a radial bearing or a thrust bearing as
long as it can reduce the sliding resistance between the adjustment spring 31 and the
adjustment sleeve 33.
[0078] Next the operation of the brake cylinder device 2 will be described with
reference FIGS. 6 to 21, which are cross-sectional views of the brake cylinder device 2.
Note that the illustration of the bellows structure disposed between the brake output
portion 21 and the cylinder body 20 is omitted in FIGS. 6 to 21. Also, FIGS. 6 to 21

are shown using the position of the cylinder body 20 as a reference, and the
components other than the cylinder body 20 are shown in their relative positions with
respect to the cylinder body 20.
[0079] Further, in FEGS. 6 to 17, the position of an end 21b of the brake output
portion 21 in the braking direction that allows the brake output portion 21 to move
relative to the cylinder body 20 to enable the braking operation is indicated by the
two-dot chain line P (hereinafter, the position indicated by the two-dot chain line P is
referred to as the "brake operating position F'). That is, in a state in which the
position of the end 21b of the brake output portion 21 with respect to the cylinder body
20 has reached the brake operating position P (the position where a braking force can
be generated), the pair of brake pads (13,13) of the disc brake device 1 are in contact
with the brake disc 101.
[0080] FIGS. 6 to 9 are cross-sectional views of the brake cylinder device 2 for
illustrating a case where the brake cylinder device 2 is operated without performing
automatic clearance adjustment by a clearance adjustment mechanism. The
cross-sectional view of FIG. 6 shows a state before the braking operation is performed,
or in other words, a break-released state. The distance Dl between the end 21b of the
brake output portion 21 and the brake operating position P in this state is indicated by
the arrows in the drawing.
[0081] During the braking operation, first, a transition from the state shown in the
cross-sectional view of FIG. 6 to the state shown in the cross-sectional view of FIG. 7 is
made by supply of compressed air to the pressure chamber 37. That is, as
compressed air is supplied to the pressure chamber 37, the piston 22 moves in the
braking direction together with the guide tube 25 against the biasing force of the
piston spring 23. Then, the threaded shaft 24 moves in the braking direction together

with the guide tube 25 and the pusher spring 26, and the end 21b of the brake output
portion 21 reaches the brake operating position P. Note that the state shown in FIG.
7 is a state at an instant when the pair of brake pads (13,13) have come into contact
with the brake disc 101 as a result of the end 21b of the brake output portion 21
having reached the brake operating position P, and no braking force has been
generated in this state.
[0082] In the state shown in FIG. 7, the movement, in the braking direction, of the
threaded shaft 24 and the clutch nut 27 threadably engaged therewith is constrained.
Then, the supply of compressed air to the pressure chamber 37 is further continued
from the state shown in FIG. 7, and thereby, as shown in the cross-sectional view of
FIG. 8, the guide tube 25 moves in the braking direction together with the piston 22,
which causes the front stopper 28 and the first clutch 29 to move toward the front (in
the braking direction) together with the guide tube 25. Consequently, the front
stopper 28 that has been in contact with the clutch nut 27 is spaced apart from the
clutch nut 27, and the first clutch 29 that has been spaced apart from the clutch nut 27
is in contact with the clutch nut 27. Upon reaching the state shown in FIG. 8, the
pair of brake pads (13,13) press the brake disc 101, and braking force is output.
[0083] On the contrary, during the brake releasing operation, the compressed air is
discharged from the pressure chamber 37. When the compressed air is discharged
from the pressure chamber 37, the piston 22 moves in the anti-braking direction
together with the guide tube 25 by the biasing force of the piston spring 23. Then, the
front stopper 28 and the first clutch 29 move to the rear Gn the anti-braking direction)
together with the guide tube 25. At this time, because the threaded shaft 24 is biased
in the braking direction by the pusher spring 26, a state temporally occurs in which
the clutch nut 27 threadably engaged with the threaded shaft 24 is spaced apart from

both the first clutch 29 and the front stopper 28, as shown in the cross-sectional view of
FIG. 9. That is, a state temporarily occurs in which the first clutch 29 that has been
in contact with the clutch nut 27 is spaced apart from the clutch nut 27, and the front
stopper 28 that has been spaced apart from the clutch nut 27 is not yet in contact with
the clutch nut 27.
[0084] As shown in FIG. 9, in the state in which the clutch nut 27 is spaced apart
from both the first clutch 29 and the front stopper 28, rotation of the clutch nut 27 is
not constrained either by the front stopper 28 or the first clutch 29. However, in this
state as well, the adjustment spring 31 is in contact at the first end thereof with the
second clutch 32, and biases, at the second end, the clutch nut 27 in the anti-braking
direction via the spring receiver (spring stopper 34, bearing 40) and the adjustment
sleeve 33. Therefore, the state in which the second clutch 32 and the clutch nut 27
are in contact with each other is maintained in a state in which the teeth 32a on the
second clutch 32 side and the teeth 27b on the clutch.nut 27 side are engaged with
each other. Thereby, in the state shown in FIG. 9, the clutch nut 27 is prevented from
rotating with respect to the threaded shaft 24.
[0085] Accordingly, in the case where the clearance adjustment by the clearance
adjustment mechanism is unnecessary and the brake cylinder device 2 operates, a
state in which the second clutch 32 and the clutch nut 27 are in contact with each
other is maintained even if the state occurs in which the clutch nut 27 is spaced apart
from both the front stopper 28 and the first clutch 29. Also, even if vibration or the
like occurs, the clutch nut 27 is prevented from rotating and positionally shifting with
respect to the threaded shaft 24.
[0086] Discharge of the compressed air from the pressure chamber 37 is further
continued through the transition from the state shown in FIG. 8 to the state shown in

FIG. 9, and thereby, the brake cylinder device 2 momentarily shifts to the same state
as the state shown in FIG. 7. In other words, the clutch nut 27, which has achieved
the state of being spaced apart from the first clutch 29, and thus being spaced apart
from both the front stopper 28 and the first clutch 29, comes in contact with the front
stopper 28.
[0087] After the state in which the brake cylinder device 2 momentarily shifts to the
same state as the state shown in FIG. 7, the discharge of the compressed air from the
pressure chamber 37 is further continued, and thereby the piston 22 and the guide
tube 25 move further in the anti-braking direction. Thereby, the front stopper 28
biases the clutch nut 27 and the threaded shaft 24 in the anti-braking direction with
the movement of the guide tube 25 in the anti-braking direction. In other words, the
clutch nut 27 in contact with the front stopper 28 and the threaded shaft 24 threadably
engaged with the clutch nut 27 also move in the anti-braking direction. Consequently,
a brake-released state is achieved as shown in FIG. 6. In the braking operation and
brake releasing operation shown in FIGS. 6 to 9, as described above, the clutch nut 27
does not rotate with respect to the threaded shaft 24, and therefore, the automatic
clearance adjustment by the clearance adjustment mechanism will not be performed.
That is, the distance Dl between the end 21b of the brake output portion 21 and the
brake operating position P does not change before and after the time at which the
above-described braking operation and brake releasing operation are performed.
[0088] Next, the operation of the brake cylinder device 2 in the case of performing the
automatic clearance adjustment by the clearance adjustment mechanism will be
described with reference to FIGS. 10 to 17. The cross-sectional view of FIG. 10 shows
a state before the braking operation is performed, or in other words a brake-released
state. The distance D2 between the end 21b of the brake output portion 21 and the

brake operating position P in this state is indicated by the arrows in the drawing. In
the state shown in FIG. 10, the distance D2, which is the clearance from the end 21b of
the brake output portion 21 up to the brake operating position P in the brake-released
state, is increased, for example, as a result of wear of the brake pads 13. That is, in
this state, the distance D2 is larger than the distance Dl CD2 > Dl). In this case, as
will be described below, the above-described clearance is automatically adjusted by the
clearance adjustment mechanism composed of the clutch nut 27, the first clutch 29,
the second clutch 32, the threaded shaft 24, the guide tube 25, the pusher spring 26,
the front stopper 28, the adjustment stoppers 30, the adjustment spring 31, and so
forth.
[0089] During the braking operation, first, a transition from the state shown in the
cross-sectional view of FIG. 10 to the state shown in the cross-sectional view of FIG. 11
is made by supply of compressed air to the pressure chamber 37. That is, as
compressed air is supplied to the pressure chamber 37, the piston 22 moves in the
braking direction together with the guide tube 25 against the biasing force of the
piston spring 23. Furthermore, the threaded shaft 24 moves in the braking direction
together with the guide tube 25 and the pusher spring 26, and the spring receiver
(spring stopper 34, bearing 40), the adjustment spring 31, the second clutch 32, and
the adjustment stoppers 30 also move in the braking direction together with the
adjustment sleeve 33 engaged with the clutch nut 27 threadably engaged with the
threaded shaft 24. At this time, the teeth 32a on the second clutch 32 side and the
teeth 27b on the clutch nut 27 side stay meshed and engaged with each other, and the
state in which the second clutch 32 and the clutch nut 27 are in contact with each
other is maintained. Then, as shown in the cross-sectional view of FIG. 11, the
adjustment stoppers 30 fixed to the second clutch 32 come in contact with the ends of

the stopper stroke restricting portions 39 in the braking direction. Consequently, the
adjustment stoppers 30 reach their forward limit, and thereby the movement of the
cylinder body 20 toward the front (in the braking direction) is restricted.
[0090] In the state shown in FIG. 11, the movement of the adjustment stoppers 30
and the second clutch 32 with respect to the cylinder body 20 is restricted, whereas the
guide tube 25, the pusher spring 26, the threaded shaft 24, the clutch nut 27, the
adjustment sleeve 33, the spring stopper 34, and the bearing 40 are in a state in which
they are movable together with the piston 22. Also, the supply of compressed air to
the pressure chamber 37 is further continued from the state shown in FIG. 11, and
thereby the end 21b of the brake output portion 21 reaches the brake operating
position P, resulting in a transition to the state shown in the cross-sectional view of
FIG. 12. At this time, the adjustment spring 31 is compressed between the second
clutch 32 to which the adjustment stoppers 30 are fixed and the spring stopper 34
disposed at the end of the adjustment sleeve 33 in the anti-braking direction along
with the movement of the above-described components (24 to 27, 33, 34, 40).
[0091] During the transition from the state shown in FIG. 11 to the state shown in
FIG. 12, the range of movement of the adjustment stoppers 30 is restricted, and
thereby a force capable of biasing the clutch nut 27 in the anti-braking direction via
the spring stopper 34, the bearing 40, and the adjustment sleeve 33 is accumulated in
the adjustment spring 31 as the accumulated force of the adjustment spring 31. Then,
as indicated by the arrows in FIG. 12, the clutch nut 27 integrated with the
adjustment sleeve 33 moves by a distance Fl relative to the second clutch 32 to which
the adjustment stoppers 30, whose range of movement is restricted by the cylinder
body 20, are fixed. That is, the teeth 32a on the second clutch 32 side and the teeth
27b on the clutch nut 27 side are disengaged, the contact of the second clutch 32 with

the clutch nut 27 is released, and a clearance of the distance Fl is formed between the
second clutch 32 and the clutch nut 27. The adjustment spring 31 is compressed by a
dimension equal to the distance Fl (the dimension Fl), and the accumulated force of
the adjustment spring 31 is stored.
[0092] The state shown in FIG. 12 is a state at an instant when the pair of brake
pads (13, 13) have come into contact with the brake disc 101 as a result of the end 21b
of the brake output portion 21 having reached the brake operating position P, and no
braking force has been generated in this state. In this state, the movement, in the
braking direction, of the threaded shaft 24 and the clutch nut 27 threadably engaged
therewith is constrained. Then, the supply of compressed air to the pressure chamber
37 is further continued from the state shown in FIG. 12, and thereby, as shown in the
cross-sectional view of FIG. 13, the guide tube 25 moves in the braking direction
together with the piston 22, which causes the front stopper 28 and the first clutch 29 to
move toward the front Gn the braking direction) together with the guide tube 25.
Consequently the front stopper 28 that has been in contact with the clutch nut 27 is
spaced apart from the clutch nut 27, and the first clutch 29 that has been spaced apart
from the clutch nut 27 is in contact with the clutch nut 27. Upon reaching the state
shown in FIG. 13, the pair of brake pads (13,13) press the brake disc 101, and braking
force is output. Also, in this state, the accumulated force of the adjustment spring 31
corresponding to the compressed dimension of the dimension Fl shown in FIG. 11 is
maintained as it is.
[0093] Note that although the present embodiment will be described as below, taking,
as an example, a mode in which the clearance adjustment operation is performed only
during the brake releasing operation, this need not be the case. In the middle of the
transition process of the brake cylinder device 2 from the state shown in FIG. 12 to the

state shown in FIG. 13, while the state is occurring in which the clutch nut 27 is
spaced apart from both the front stopper 28 and the first clutch 29, the clearance
adjustment operation may be performed as a result of the clutch nut 27 spaced apart
also from the second clutch 32 rotating and moving with respect to the threaded shaft
24 due to the accumulated force of the adjustment spring 31.
[0094] On the other hand, during the brake releasing operation, the compressed air
is discharged from the pressure chamber 37. Upon the compressed air being
discharged from the pressure chamber 37, the piston 22 starts moving in the
anti-braking direction together with the guide tube 25 by the biasing force of the piston
spring 23. Then, the front stopper 28 and the first clutch 29 also start moving to the
rear (in the anti-braking direction) together with the guide tube 25. At this time,
although the clutch nut 27 undergoes a transition to the state in which it is spaced
apart from the first clutch 29 and is in contact with the front stopper 28, the threaded
shaft 24 is biased in the braking direction by the pusher spring 26. Accordingly, as
shown in the cross-sectional view of FIG. 14, the threaded shaft 24 and the brake
output portion 21 do not move in the anti-braking direction, resulting in a state in
which the clutch nut 27 is biased in the anti-braking direction by the accumulated
force corresponding to the dimension Fl of the adjustment spring 31. At this time, a
state occurs in which the contact of the clutch nut 27 with the first clutch 29 is released
and the clutch nut 27 is not in contact with the front stopper 28, and further, the clutch
nut 27, which is not in contact with the second clutch 32 either, becomes rotatable with
respect to the threaded shaft 24 in this state.
[0095] In the state in which the clutch nut 27 is not in contact with the front stopper
28, the first clutch 29, or the second clutch 32, and thus is rotatable with respect to the
threaded shaft 24 as described above, the accumulated force of the adjustment spring

31 that corresponds to the dimension Fl of the adjustment spring 31 causes the clutch
nut 27 to rotate with respect to the threaded shaft 24 so as to move in the anti-braking
direction. Thus, rotation of the clutch nut 27 with respect to the threaded shaft 24
reduces the dimension Fl shown in FIG. 14. Also, as shown in FIG. 15, the state in
which the clutch nut 27 is not in contact with the front stopper 28, the first clutch 29,
or the second clutch 32 and thus rotates with respect to the threaded shaft 24 is
continued until the clearance between the clutch nut 27 and the second clutch 32 is
lost, the clutch nut 27 and the second clutch 32 come in contact with each other, and
the dimension Fl becomes zero. As a result of the dimension Fl thus becoming zero,
the clutch nut 27 becomes unrotatable. Note that the rotation of the clutch nut 27
performed until the dimension Fl becomes zero does not necessarily be completed
during the time in which the braking operation and the brake releasing operation are
performed once, but may be completed during the time in which the braking operation
and the brake releasing operation are performed multiple times.
[0096] The discharge of the compressed air from the pressure chamber 37 is further
continued from the state shown in FIG. 15, and thereby the piston 22, the guide tube
25, and the front stopper 28 move further in the anti-braking direction. Then, as
shown in the cross-sectional view of FIG. 16, the front stopper 28 comes into contact
with the clutch nut 27. Furthermore, as a result of the movement of the guide tube
25 in the anti-braking direction, the clutch nut 27 in contact with the front stopper 28
and the threaded shaft 24 threadably engaged with the clutch nut 27 also move in the
anti-braking direction. Consequently, the brake output portion 21 also moves in the
anti'braking direction, and a brake-released state is achieved as shown in FIG. 17.
[0097] Then, in the brake-released state shown in FIG. 17, compared to the state
before the braking operation and the brake releasing operation are performed, the

distance between the end 21b of the brake output portion 21 and the brake operating
position P changes to a distance D3, which is a distance smaller than the distance D2
(D3 < D2). That is, the clutch nut 27 moves relative to the threaded shaft 24 in the
antrbraking direction in the middle of the brake releasing operation, and therefore,
the brake releasing operation ends in a state in which the position of the threaded
shaft 24 has moved further in the braking direction than in the state before the brake
releasing operation. Then, a transition is made to a state in which the threaded shaft
24 and the brake output portion 21 have moved to positions projecting toward the
cylinder body 20, as compared to the state before the braking operation and the brake
releasing operation. Consequently, the clearance up to the brake operating position P
in the brake-released state is automatically adjusted.
[0098] Next, with reference to FIGS. 18 to 21, a description will be given of the
operation of the brake cylinder device 2 in the case of forcibly performing the clearance
adjustment operation in a state in which the brake pads 13 do not come into contact
with the brake disc 101 and braking force is not generated with a conventional
clearance adjustment operation, or in the so-called idling state (note that the clearance
adjustment is performed using the force generated by the brake pads 13 coming into
contact with the brake disc 101, and the clearance adjustment cannot be performed
without such contact). The cross-sectional view of FIG. 18 shows a state before the
compressed air is supplied to the compression chamber 37 in the above-described
idling state (i.e., a state corresponding to the above-described brake-released state).
For example, the drawing shows a state after the replacement of the brake pads 13 of
the disc brake device 1 has been performed and in which the clearance adjustment
operation is about to be performed.
[0099] In the above case, first, a transition from the state shown in the cross-sectional

view of FIG. 18 to the state shown in the cross-sectional view of FIG. 19 is made by
supply of compressed air to the pressure chamber 37. That is, as compressed air is
supplied to the pressure chamber 37, the piston 22 moves in the braking direction
together with the guide tube 25 against the biasing force of the piston spring 23.
Furthermore, the threaded shaft 24 moves in the braking direction together with the
guide tube 25 and the pusher spring 26, and the second clutch 32, the adjustment
stoppers 30, and the adjustment spring 31 also move in the braking direction together
with the adjustment sleeve 33 engaged with the clutch nut 27 threadably engaged
with the threaded shaft 24. Then, as shown in the cross-sectional view of FIG. 19, the
adjustment stoppers 30 fixed to the second clutch 32 come into contact with the end of
the stroke restricting portions 39 in the braking direction. Consequently, the
adjustment stoppers 30 reach their forward limit, and thereby their movement with
respect to the cylinder body 20 toward the front (in the braking direction) is restricted.
[0100] In the state shown in FIG. 19, the movement of the adjustment stoppers 30
and the second clutch 32 with respect to the cylinder body 20 is restricted, whereas
predetermined components such as the threaded shaft 24 (24 to 27, 33, 34, 40) are in a
state in which they are movable together with the piston 22. Also, the supply of
compressed air to the pressure chamber 37 is further continued from the state shown
in FIG. 19, and thereby the adjustment spring 31 is compressed between the second
clutch 32 to which the adjustment stoppers 30 are fixed and the spring stopper 34
disposed at the end of the adjustment sleeve 33 in the anti-braking direction along
with the movement of the above-described components (24 to 27, 33, 34, 40). Then,
the end of the spring stopper 34 in the braking direction comes into contact with the
end of the second clutch 32 in the anti-braking direction, resulting in a transition to the
state shown in the cross-sectional view of FIG. 20.

[0101] In the state shown in FIG. 20, a force capable of biasing the clutch nut 27 in
the anti-braking direction via the spring stopper 34, the bearing 40, and the
adjustment sleeve 33 is accumulated in the adjustment spring 31 as the accumulated
force of the adjustment spring 31. At this time, as indicated by the arrows in FIG. 20,
the clutch nut 27 integrated with the adjustment sleeve 33 moves by a distance F2
relative to the second clutch 32 to which the adjustment stoppers 30 are fixed whose
range of movement is restricted by the cylinder body 20. The adjustment spring 31 is
compressed by a dimension equal to the distance F2 (the dimension F2), and the
accumulated force of the adjustment spring 31 is stored.
[0102] As shown in FIG. 20, in the state in which the movement of the adjustment
stoppers 30 is restricted and the second clutch 32 to which the adjustment stoppers 30
are fixed is in contact with the spring stopper 34, the adjustment sleeve 33 whose end
in the anti-braking direction engaged with the bearing 40 in contact with the spring
stopper 34 can no longer move to the front (in the braking direction). Accordingly, the
clutch nut 27 engaged with the adjustment sleeve 33 can no longer move in the
braking direction either, and the clutch nut 27 can no longer move in the braking
direction together with the piston 22, the guide tube 25, the pusher spring 26, and the
threaded shaft 24.
[0103] However, because the brake pad 13 does not come in contact with the brake
disc 101, the supply of the compressed air to the pressure chamber 37 is further
continued from the state shown in FIG. 20, resulting in further movement in the
braking direction of the piston 22, the guide tube 25, the front stopper 28, the first
clutch 29, the pusher spring 26, and the pusher spring guide 38. Thereby, a state
occurs in which the clutch nut 27 is spaced apart from the front stopper 28, and
remains spaced apart from and is not in contact with the first clutch 29 as well, as

shown in the cross-sectional view of FIG. 21. Therefore, a state is achieved in which
the clutch nut 27 is in contact with none of the front stopper 28, the first clutch 29, and
the second clutch 32, and is rotatable with respect to the threaded shaft 24. At this
time, the threaded shaft 24 is biased by the pusher spring 26, and therefore the clutch
nut 27 rotates with respect to the threaded shaft 24 by the biasing force of the pusher
spring 26. Consequently, the threaded shaft 24 moves and protrudes relative to the
clutch nut 27 in the braking direction. Then, upon the brake pad 13 coming in
contact with the brake disc 101, movement of the threaded shaft 24 due to the biasing
force of the pusher spring 26 stops, and the rotation of the clutch nut 27 with respect to
the threaded shaft 24 stops. Note that even in the case where the brake pad 13 does
not come in contact with the brake disc 101, the rotation of the clutch nut 27 with
respect to the threaded shaft 24 by the biasing force of the pusher spring 26 stops if the
pusher spring 26 extends and the biasing force of the pusher spring 26 becomes
sufficiently small.
[0104] As described above, even in the state in which the rotation of the clutch nut 27
with respect to the threaded shaft 24 by the biasing force of the pusher spring 26 stops,
the clutch nut 27 is in contact with none of the front stopper 28, the first clutch 29, and
the second clutch 32, and is rotatable with respect to the threaded shaft 24. Therefore,
the clutch nut 27 is biased by the accumulated force stored in the adjustment spring 31,
and rotates with respect to the threaded shaft 24 so as to move in the anti-braking
direction. Thus, the clutch nut 27, by rotating with respect to the threaded shaft 24,
comes in contact with the first clutch 29. In this state, the clearance adjustment
mechanism is in a state similar to the state shown in the cross-sectional view of FIG.
13, that is, a state similar to the state in which braking force has been output in the
case where the automatic clearance adjustment by the clearance adjustment

mechanism is performed. In this state, an operation corresponding to the braking
operation ends. Then, after the operation corresponding to the braking operation
ends, the compressed air is discharged from the pressure chamber 37, and an
operation corresponding to the brake releasing operation is performed in a manner
similar to the brake releasing operation illustrated in FIGS. 14 to 16. As a result of
the operation corresponding to the brake releasing operation, an operation similar to
the the clearance adjustment operation illustrated in FIGS. 14 to 16 is performed by
the clearance adjustment mechanism. Also, the state in which the operation similar
to the clearance adjustment operation is performed, that is, the state in which the
clutch nut 27 is in contact with none of the front stopper 28, the first clutch 29, and the
second clutch 32 and thus rotates with respect to the threaded shaft 24 is continued
until the clearance between the clutch nut 27 and the second clutch 32 is lost and the
clutch nut 27 and the second clutch 32 come in contact with each other. Note that the
rotation of the clutch nut 27 performed until the clutch nut 27 and the second clutch 32
come in contact with each other is not necessarily completed during the time in which
the operations corresponding to the braking operation and the brake releasing
operation are performed once, but may be completed during the time in which the
operations corresponding to the braking operation and the brake releasing operation
are performed multiple times.
[0105] Thus, in the idling state as well, the clutch nut 27 moves relative to the
threaded shaft 24 in the anti-braking direction as a result of the operation
corresponding to the braking operation and the operation corresponding to the brake
releasing operation being performed, and therefore, these operations end in a state in
which the position of the threaded shaft 24 has moved further in the braking direction
than in the state before the operation corresponding to the braking operation and the

operation corresponding to the brake releasing operation are performed. Then, a
transition is made to a state in which the threaded shaft 24 and the brake output
portion 21 have moved to positions projecting toward the cylinder body 20, as
compared to the state before the operation corresponding to the braking operation and
the operation corresponding to the brake releasing operation are performed
Consequently, the clearance up to the brake operating position P in the brake-released
state has been automatically adjusted when the maintenance operation such as the
replacement of the brake pads 13 has ended and a transition has been made from the
idling state to the state in which the brake is operable.
[0106] As described thus far, with the brake cylinder device 2, the clearance
adjustment mechanism is composed of the clutch nut 27, the first clutch 29, the second
clutch 32, the threaded shaft 24, the guide tube 25, the pusher spring 26, the front
stopper 28, the adjustment stoppers 30, the adjustment spring 31, and so forth.
Accordingly, the clearance adjustment is not performed using elastic deformation of
rubber or the like, and it is therefore possible to achieve a configuration that is less
likely to be affected by the surrounding environment such as temperature and
humidity. Also, it is not necessary to provide the bearing in the structure for
attaching the guide tube 25 to the piston 22, which makes it possible to reduce the
radial dimension of the cylinder body 20 on the rear side (the end in the anti-braking
direction).
[0107] Therefore, according to the present embodiment, for the brake cylinder device
2 including the clearance adjustment mechanism for automatically adjusting the
clearance up to the brake operating position P in the brake-released state, it is possible
to provide a configuration that is less likely to be affected by the surrounding
environment such as temperature and humidity at low cost, and also achieve a

reduction in the radial dimension of the cylinder body 20.
[0108] Furthermore, with the brake cylinder device 2, in the state in which the
automatic clearance adjustment operation by the clearance adjustment mechanism is
not performed, the state in which the second clutch 32 and the clutch nut 27 are in
contact with each other is maintained regardless of whether it is during the braking
operation or when the brake is released, and the contact of the second clutch 32 with
the clutch nut 27 is prevented from being released. In other words, in the state in
which the clearance adjustment operation is not performed, the clutch nut 27 is biased
in the anti-braking direction by the adjustment spring 31 in contact at the first end
thereof with the second clutch 32, and thereby the state in which the second clutch 32
and the clutch nut 27 are in contact with each other is maintained Consequently, the
clutch nut 27 is prevented from rotating with respect to the threaded shaft 24 at any
time other than during the clearance adjustment operation, and the position of the
clutch nut 27 with respect to the threaded shaft 24 is prevented from shifting due to
vibration or the like.
[0109] Note that if the position of the clutch nut 27 with respect to the threaded shaft
24 shifts due to vibration or the like, a state occurs in which the brake output portion
21 excessively protrudes in the braking direction toward the cylinder body 20, or in
which protrusion of the brake output portion 21 in the braking direction toward the
cylinder body 20 is insufficient. In the state in which the position of the clutch nut 27
with respect to the threaded shaft 24 shifts and the brake output portion 21
excessively protrudes in the braking direction toward the cylinder body 20, that is, in
the state in which excessive clearance adjustment has been performed, a state occurs
in which the brake pad 13 is in constant contact with, and is rubbed against, the brake
disc 101. In this case, it is likely that wear of the brake pad 13 is promoted, and the

replacement cycle of the brake pad 13 is shortened. On the other hand, in the state in
which the position of the clutch nut 27 with respect to the threaded shaft 24 shifts and
the protrusion of the brake output portion 21 in the braking direction toward the
cylinder body 20 is insufficient, that is, in the state in which the clearance adjustment
is insufficient, the timing of braking force generation during the braking operation is
delayed even in a situation in which the clearance adjustment is originally not
necessary.
[0110] However, with the brake cylinder device 2, the clutch nut 27 is prevented from
rotating with respect to the threaded shaft 24 at any time other than during the
clearance adjustment operation, and the position of the clutch nut 27 with respect to
the threaded shaft 24 is prevented from shifting due to vibration or the like, as
described above. Therefore, it is possible to prevent occurrence of an event in which
wear of the brake pad 13 is promoted and the replacement cycle of the brake pad 13 is
shortened, and an event in which the timing of braking force generation during the
braking operation is delayed even in the situation in which the clearance adjustment is
originally not necessary.
[0111] With the brake cylinder device 2, the pusher spring 26 that biases the
threaded shaft 24 is disposed inside the threaded shaft 24 having a hollow structure,
and is configured to bias the clutch nut 27 threadably engaged with the threaded shaft
24 toward the front stopper 28. Accordingly, the pusher spring 26 can be disposed by
efficiently using the space in the brake cylinder device 2. This can increase the space
efficiency in the brake cylinder device 2, which makes it possible to realize a farther
size reduction.
[0112] With the brake cylinder device 2, the pusher spring guide 38 is provided that
extends inside the coil-shaped pusher spring 26 and restricts the deformation of the

pusher spring 26 in the buckling direction. Accordingly, the dimension of the
clearance to be adjusted by the clearance adjustment mechanism is increased, and
therefore, the buckling of the pusher spring 26 can be efficiently prevented even if a
long pusher spring 26 is required. Further, the pusher spring guide 38 provided so as
to be movable together with the guide tube 25 is disposed such that its tip is slidable
on the inside of the threaded shaft 24. Accordingly, it is possible, with a simple
configuration of providing the shaft-like pusher spring guide 38, to readily achieve a
structure that maintains the positional relationship between the threaded shaft 24
and the piston 22 such that they are displaced coaxially.
[0113] With the brake cylinder device 2, the front stopper 28 and the first clutch 29
are provided as separate unitary members and are separately fixed to the guide tube
25. Accordingly, it is not necessary to provide each of the front stopper 28 and the first
clutch 29 disposed at the front and the rear, respectively, of the clutch nut 27 as a
divided structure and perform coupling with additional coupling means. Likewise, it
is not necessary to provide the clutch nut 27 at the front and the rear of which the
front stopper 28 and the first clutch 29 are disposed as a divided structure and perform
coupling with additional coupling means. This can simplify the configuration for the
front stopper 28, the first clutch 29, and the clutch nut 27, and consequently, the size
and the weight of the brake cylinder device 2 as a whole can be reduced.
Furthermore, due to the configuration in which the front stopper 28 and the first
clutch 29 are separate unitary members and are fixed to the guide tube 25, it is
possible to set the dimensional configuration such that the inner circumferences of the
front stopper 28 and the first clutch 29 are located closer to the outer circumference of
the threaded shaft 24, which makes it possible to realize a further size reduction for
the brake cylinder device 2.

[0114] With the brake cylinder device 2, the front stopper 28 provided as a separate
unitary member is fixed to the inner circumference of the guide tube 25 by threaded
coupling. Accordingly, the front stopper 28 can be readily replaced at the time of
maintenance, which makes it possible to increase the ease of maintenance.
[0115] With the brake cylinder device 2, the adjustment spring 31 is disposed
between the tubular adjustment sleeve 33 disposed around the threaded shaft 24 and
the second clutch 32 to which the adjustment stoppers 30 are fixed, and a force for
moving the clutch nut 27 relative to the threaded shaft 24 in the anti-braking direction
is accumulated during the clearance adjustment operation along with the relative
movement of the adjustment sleeve 33 with respect to the adjustment stoppers 30 and
the second clutch 32. Also, the adjustment sleeve 33 is provided as a member having
flexibility, and the adjustment sleeve 33 and the clutch nut 27 are integrated by
engagement of the engaging portion 33a on the adjustment sleeve 33 side and the
engaged portion 27c on the clutch nut 27 side. Accordingly, the engaging portion 33a
can be engaged with the engaged portion 27c by temporarily causing the adjustment
sleeve 33 having flexibility to be elastically deformed, and therefore, the adjustment
sleeve 33 and the clutch nut 27 can be integrated without using any additional
fastening member. Thus, the structure for integrating the adjustment sleeve 33 and
the clutch nut 27 does not require any additional fastening member, and it is therefore
possible to achieve a further size reduction for the brake cylinder device 2.
[0116] With the brake cylinder device 2, the adjustment sleeve 33 is configured to
engage from inside of the clutch nut 27, and the dimension of the clearance between
the inner circumference of the adjustment sleeve 33 and the top of the ridge of the
thread 24a of the threaded shaft 24 is set to be smaller than the radial dimension of
the indented portions of the engaging portion 33a and the engaged portion 27c that are

fitted together (the length, in the radial direction of the adjustment sleeve 33, of
overlap of the indented portions). Accordingly, the engaging portion 33a of the
adjustment sleeve 33 having flexibility is disposed between the clutch nut 27 and the
threaded shaft 24 that are formed of a metallic material, and, moreover, a dimensional
relationship is set that can prevent disengagement of the engaging portion 33a of the
adjustment sleeve 33 from the engaged portion 27c caused by deformation toward the
threaded shaft 24. This makes it possible to firmly integrate the adjustment sleeve
33 and the clutch nut 27 even though the engagement configuration is simple.
[0117] With the brake cylinder device 2, the second end of the adjustment spring 31
biases the adjustment sleeve 33 via the bearing 40, and therefore, when the
adjustment sleeve 33 is biased by the accumulated force of the adjustment spring 31,
the clutch nut 27 smoothly rotates together with the adjustment sleeve 33 and moves
in the braking direction. Also, the bearing 40 of the spring receiver is disposed such
that the clearance to the guide tube 25 is substantially zero, or is disposed so as to be in
sliding contact with the guide tube 25, and therefore, the threaded shaft 24 can be
supported to the guide tube 25 via the bearing 40 of the spring receiver, which makes it
possible to prevent the threaded shaft 24 from being tilted with respect to the guide
tube 25.
[0118] With the brake cylinder device 2, the spring stopper 34 is provided that
restricts, to a predetermined amount or less, the amount of displacement of the
adjustment spring 31 during the elastic deformation of the adjustment spring 31 such
that the force for the clearance adjustment operation is accumulated. Accordingly,
even if the clearance adjustment operation is forcibly performed in an operation in the
idling state that does not generate braking force with a conventional clearance
adjustment operation, the stroke of the adjustment spring 31 is restricted by the

spring stopper 34. Accordingly, the adjustment spring 31 will not be excessively
compressed or extended, and the clearance adjustment operation can be performed
forcibly even in the idling state.
[0119] With the brake cylinder device 2, it is possible to forcibly perform the clearance
adjustment operation even in the idling state as described above. Accordingly, by
repeating operations corresponding to the braking operation and the brake releasing
operation multiple times for the entire vehicle or the entire group of vehicles at once,
the clearance is automatically adjusted in all brake cylinder devices 2. Thereby, when
the brake pads 13 have been replaced, it is possible to automatically perform the
clearance adjustment on all brake cylinder devices 2 in a vehicle or a group of vehicles
at once, without the need to manually perform the clearance adjustment on brake
cylinder devices 2 one by one. Accordingly it is possible to significantly reduce the
number of steps and time and effort in the operation associated with the replacement
of brake pads 13, which makes it possible to considerably promote the efficiency.
[0120] With the brake cylinder device 2, in a state in which the clearance adjustment
operation is not performed and the contact of the clutch nut 27 with the second clutch
32 is maintained, the clutch nut 27 and the second clutch 32 engage with each other
via the teeth (27b, 32a) formed on the mutually facing surfaces, and it is therefore
possible to reliably prevent the clutch nut 27 from rotating with respect to the
threaded shaft 24 due to vibrations or the like. Note that the clutch nut 27 and the
second clutch 32 engage with each other via the teeth (27b, 32a), and it is therefore
possible to reliably prevent the clutch nut 27 from rotating with respect to the
threaded shaft 24 even if the engagement is made in a state in which only the tips of
the teeth (27b, 32a) are meshed.
[0121] With the brake cylinder device 2, the hexagon head portion 24c serving as the

operation engaging portion is provided at the tip disposed so as to pass through the
brake output portion 21 and face outward, and the threaded shaft 24 and the brake
output portion 21 are engaged with each other by the engagement mechanism 42
disposed on the outer circumference of the threaded shaft 24 at the tip. Further, the
engagement mechanism 42 includes the engaging spring 44 and the outer
circumferential engaging portion 43 having the engaging teeth 43a, and the threaded
shaft 24 and the brake output portion 21 are configured to engage with each other via
the engaging teeth 43a by the engaging spring 44 biasing the outer circumferential
engaging portion 43 in the braking direction. Accordingly, by releasing the
engagement of the outer circumferential engaging portion 43 with the brake output
portion 21 via the engaging teeth 43a against the spring force of the engaging spring
44 to release the engagement of the threaded shaft 24 with the brake output portion
21 and further rotating the threaded shaft 24 with an operation tool, the threaded
shaft 24 can be rotated manually. Thus the positional relationship between the
threaded shaft 24 and the clutch nut 27 can be readily brought back into the initial
state, which is the state before the clearance adjustment is performed.
[0122] According to this embodiment, for the disc brake device 1 provided with the
brake cylinder device 2 including the clearance adjustment mechanism for
automatically adjusting the clearance up to the brake operating position P in the
brake-released state, it is possible to provide a configuration that is less likely to be
affected by the surrounding environment such as temperature and humidity at low
cost, and also achieve a reduction in the radial dimension of the cylinder body 20.
[0123] Second Embodiment
Next, a brake cylinder device 3 according to a second embodiment of the
present invention will be described. FIG. 22 is a cross-sectional view of a brake

cylinder device 3 according to the second embodiment. As with the brake cylinder
device 2 of the first embodiment, the brake cylinder device 3 shown in FTG. 22 is
provided as a brake cylinder device with which the disc brake device 1 is equipped.
Note that FIG. 22 shows the outer shape, rather than the cross section, of some of the
components of the brake cylinder device 3.
[0124] As with the brake cylinder device 2 of the first embodiment, the brake cylinder
device 3 includes a cylinder body 20, a brake output portion 21, a piston 50, piston
springs 23, a threaded shaft 24, a guide tube 25, a pusher spring 26, a clutch nut 27, a
front stopper 28, a first clutch 29, adjustment stoppers 30, an adjustment spring 31, a
second clutch 32, an adjustment sleeve 33, a spring stopper 34, a pusher spring guide
38, a bearing 40, an engagement mechanism 42, and so forth. Of the above-described
components, those other than the adjustment sleeve 33 are formed of for example, a
metallic material such as an iron-based material, and the adjustment sleeve 33 is
formed of, for example, a resin material.
[0125] As described above, the brake cylinder device 3 is configured in the same
manner as the brake cylinder device 2 of the first embodiment. However, the brake
cylinder device 3 is different from the brake cylinder device 2 of the first embodiment
in that a force amplifying mechanism 51 is further provided and that the direction of
movement of the piston 50 is configured such that the piston 50 moves in the direction
opposite to the direction of movement of the piston 22 of the first embodiment. Note
that in the following description of the brake cylinder device 3, a description will only
be given of configurations that are different from those of the first embodiment.
Those elements configured to have the same functions as in the first embodiment are
denoted by identical reference numerals in the drawings, and the description thereof
has been omitted.

[0126] The piston 50 includes a disc-like portion 52 and a pair of plate-like portions
53 (only one of the plate-like portions 53 is shown in FIG. 22) that project from the
disc-like portion 52 parallel to the threaded shaft 24 and the guide tube 25 in the
anti-braking direction (the direction indicated by the arrow B in FIG. 22).
Additionally, the second casing portion 36 of the cylinder 20 is provided with a cylinder
portion 54 extending toward the first casing portion 35 side (i.e., the anti-braking
direction) thereinside. Also, the disc-like portion 52 has a through hole 52a formed at
the center, and the cylinder portion 54 of the cylinder body 20 passes through the
through hole 52a. Thereby, the piston 50 is disposed between the outer
circumferential face of the cylinder portion 54 and the inner circumferential face of the
second casing 36. That is, the piston 50 is disposed so as to partition the space
between the outer circumferential face of the cylinder portion 54 and the inner
circumferential face of the second casing portion 36 into two, and is configured to be
movable relative to the cylinder body 20 along the axial direction. Also, the pressure
chamber 37 is defined between the piston 50 and the second casing portion 36.
[0127] Note that cylinder body 20 is provided with a pair of guide shafts 55 (only one
of the guide shafts 55 is shown in FIG. 22) extending parallel to the axial direction of
the threaded shaft 24 and the guide tube 25. Also, the disc-like portion 52 of the
piston 50 is provided with guide apertures 52b through which the guide shafts 55 pass.
Further, the piston springs 23 for biasing the piston 50 toward the brake output
portion 21 side (Le., toward the braking direction, which is the direction indicated by
the arrow A in FIG. 22) are disposed around the guide shafts 55.
[0128] The plate-like portions 53 of the piston 50 are each provided with an inclined
surface 53a that is inclined in a spiral fashion with respect to the direction of the
central axis of the threaded shaft 24 and the guide tube 25 and the circumferential

direction about the central axis. Note that rollers 61 rotatably attached to a pivot
member 56, which will be described below, are disposed so as to come into contact with
the inclined surfaces 53a of the plate-like portions 53.
[0129] The force amplifying mechanism 51 is provided as a mechanism for.
amplifying the force generated in the piston 50 and exerting the force on the guide
tube 25 such that the guide tube 25, the pusher spring 26, the threaded shaft 24, and
so forth are moved in the braking direction (the direction indicated by the arrow A in
FIG. 22), which is opposite to the direction of movement of the piston 50, when the
piston 50 moves in the antrbraking direction. That is, when the piston 50 moves in
the anti-braking direction inside the cylinder body 20 as a result of supply of
compressed air to the pressure chamber 37, the force amplified by the force amplifying
mechanism 51 acts on the guide tube 25 attached to the force amplifying mechanism
51, and the guide tube 25, the pusher spring 26, the threaded shaft 24, and the like
move in the braking direction. Accordingly, the brake output portion 21 connected to
the threaded shaft 24 moves in the braking direction via the force amplifying
mechanism 51 that amplifies the force generated in the piston 50 with the movement
of the piston 50 in the anti-braking direction.
[0130] The force amplifying mechanism 51 includes the above-described inclined
surfaces 53a provided in the piston 50, the pivot member 56, a first receiving member
57, a second receiving member 58, a first rolling member 59, a second rolling member
60, and so forth.
[0131] The pivot member 56 is provided as a disc-like member that pivots about the
central axis of the threaded shaft 24 and the guide tube 25 in a predetermined
direction of rotation, and has a through hole formed at the center. Also, the pivot
member 56 is configured to be biased by the inclined surfaces 53a of the piston 50

when the piston 50 has moved in the anti-braking direction, and to pivot about the
central axis of the threaded shaft 24 and the guide tube 25 in the above-described
predetermined direction of rotation. Note that the threaded shaft 24 and the guide
tube 25 are provided so as not to pivot about the central axis with respect to the
cylinder body 20, and are configured to move in the braking direction along with the
pivoting of the pivot member 56 in the above-described predetermined direction of
rotation. Further, the pivot member 56 is provided with a pair of shaft portions
projecting radially outward from the outer circumferential face of the disc-like portion,
and rollers 61 coming into contact with the inclined surfaces 53a of the piston 50 on
their outer circumferential faces are rotatably attached to the shaft portions.
[0132] The first receiving member 57 is provided as a disc-like member having a
through hole formed at the center, is disposed about the central axis of the threaded
shaft 24 and the guide tube 25, and is fixed to the outer circumference of the guide
tube 25. Also, the first receiving member 57 is disposed so as to face the pivot
member 56 on the braking direction side in a direction parallel to the direction of the
central axis of the threaded shaft 24 and the guide tube 25.
[0133] Further, the surface of the pivot member 56 that feces the first receiving
member 57 is provided with first inclined grooves (not shown) that are formed such
that the depth thereof changes in inclination with respect to the pivoting direction of
the pivot member 56. Also, first rolling members 59 (indicated by the dashed line in
FIG. 22) capable of rolling along the inner surface of the first inclined grooves are
disposed in the first inclined grooves. The first rolling members 59 are provided as
spherical members, and are supported in a state of being sandwiched by the first
receiving member 57 and the pivot member 56. Aplurality of the above-described
first inclined grooves and first rolling members 59 are provided so as to be positioned

along the circumference of a circle about the central axis of the threaded shaft 24 and
the guide tube 25. Note that a spring 62 is disposed between a stepped portion
formed on the inner circumference of the end of the first receiving member 57 in the
braking direction and a stepped portion formed on the inner wall of the cylinder
portion 54 of the second casing portion 36. The spring 62 biases the first receiving
member 57 in the anti-braking direction. Further, in the cylinder body 20 of the
brake cylinder device 3, a portion of the cylinder portion 54 that forms a stepped
portion coming into contact with the spring 62 is configured to also serve the function
of the stopper stroke restricting portions 39.
[0134] The second receiving member 58 is provided as a disc-like member having a
through hole formed at the center, is disposed about the central axis of the threaded
shaft 24 and the guide tube 25, and is fixed to the first casing portion 35 of the cylinder
body 20. Also, the second receiving member 58 is disposed so as to face the pivot
member 56 on the anti-braking direction in a direction parallel to the direction of the
central axis of the threaded shaft 24 and the guide tube 25, or in other words, is
disposed so as to face the surface opposite to the surface of the pivot member 56 that
faces the first receiving member 57.
[0135] Further, the surface of the pivot member 56 that feces the second receiving
member 58 is provided with second inclined grooves (not shown) that are formed such
that the depth thereof changes in inclination with respect to the pivoting direction of
the pivot member 56. Also, second rolling members 60 (indicated by the dashed line
in PIG. 22) capable of rolling along the inner surface of the second inclined grooves are
disposed in the second inclined grooves. The second rolling members 60 are provided
as spherical members, and are supported in a state of being sandwiched by the pivot
member 56 and the second receiving member 58. Aplurality of the above-described

second inclined grooves and second rolling members 60 are provided so as to be
positioned along the circumference of a circle about the central axis of the threaded
shaft 24 and the guide tube 25.
[0136] In the brake cylinder device 3, compressed air is supplied to the pressure
chamber 37 during the braking operation, and thereby the piston 50 moves in the
anti-braking direction against the biasing force of the piston spring 23, which causes
rotation of the rollers 61 in contact with inclined surfaces 53a of the piston 50. Then,
the rollers 61 rotate with respect to the shaft portions of the pivot member 56 and the
pivot member 56 pivots about the central axis of the threaded shaft 24 and the guide
tube 25 in a predetermined direction of rotation. As a result of pivoting of the pivot
member 56, the first rolling members 59 roll in the first inclined grooves and the
second rolling members 60 roll in the second inclined grooves. Thereby, the pivot
member 56 and the first receiving member 57 move in the braking direction relative to
the cylinder body 20. Then, the guide tube 25, the pusher spring 26, the threaded
shaft 24, and the like move in the braking direction, which causes the brake output
portion 21 to move in the braking direction.
[0137] On the other hand, when the brake releasing operation is performed in the
brake cylinder device 3, the compressed air is discharged from the pressure chamber
37, and the piston 50 moves in the braking direction by the biasing force of the piston
spring 23. Then, the pivot member 56, the first receiving member 57, the first rolling
members 59, and the second rolling members 60 move in the direction opposite to that
in the case of the above-described braking operation. Thereby, the guide tube 25, the
pusher spring 26, the threaded shaft 24, and the like move in the anti-braking
direction, which causes the brake output portion 21 to move in the anti-braking
direction. Since the first receiving member 57 is biased in the anti-braking direction

by the spring 62 during the brake releasing operation as well, the first rolling members
59 roll in the first inclined grooves and the second rolling members 60 roll in the
second inclined grooves.
[0138] Note that the clearance adjustment mechanism composed of the clutch nut 27,
the front stopper 28, the first clutch 29, the second clutch 32, the threaded shaft 24, the
guide tube 25, the pusher spring 26, the adjustment stoppers 30, the adjustment
spring 31, and so forth operates in the same manner as in the case of the first
embodiment. Therefore, in this embodiment as well, for the brake cylinder device 3
including the clearance adjustment mechanism for automatically adjusting the
clearance up to the brake operating position in the brake-released state, it is possible
to provide a configuration that is less likely to be affected by the surrounding
environment such as temperature and humidity at low cost, and also achieve a
reduction in the radial dimension of the cylinder body 20, as with the first
embodiment.
[0139] Modifications
Although the embodiments of the present invention have been described thus
far, the present invention is not limited to the above-described embodiments, and
various modifications may be made within the scope recited in the claims. For
example, the following modifications are possible.
[0140] (1) Although the first embodiment has been described, taking as an example, a
configuration in which the pusher spring is disposed so as to be capable of biasing the
threaded shaft with respect to the guide tube toward the braking direction, this need
not be the case. It is possible to adopt a configuration in which the pusher spring is
disposed so as to be capable of biasing the threaded shaft with respect to the piston
toward the braking direction.

[0141] (2) The shape and the arrangement of the adjustment spring, the adjustment
stopper, the front stopper, the adjustment sleeve, and the spring stopper are not
limited to the examples described in the embodiments, and modifications may be made.
Also, modifications may be made to the shape of the clutch nut, the first clutch, and
the second clutch.
[0142] (3) Although the above embodiments have been described, taking as an
example, a configuration in which only the front stopper is fixed to the inner
circumference of the guide tube by threaded coupling, this need not be the case. The
first clutch may also be fixed to the inner circumference of the guide tube by threaded
coupling. Further, the front stopper may be fixed to the inner circumference of the
guide tube by press fitting.
[0143] (4) Although the above embodiments have been described, taking as an
example, a configuration in which the teeth capable of engaging the second clutch with
the clutch nut are formed on both the surface of the second clutch that feces the clutch
nut and the surface of the clutch nut that faces the second clutch, this need not be the
case. It is also possible to adopt a configuration in which the teeth are formed on one
of the mutually facing surfaces.
[0144] (5) Although the above embodiments have been described, taking as an
example, a case in which compressed air is used as the pressure fluid for operating the
brake cylinder device, the pressure fluid is not limited thereto. The brake cylinder
device may be operated with other kinds of pressure fluid (e.g., pressure oil).
[0145] (6) Although the above embodiments have been described, taking, as an
example, a configuration in which the adjustment spring is in contact with, or
connected to, the second clutch at the first end, this need not be the case. It is also
possible to adopt a configuration in which the adjustment spring is in contact with, or

connected to, the adjustment stopper at the first end.
[0146] (7) In the case where the force amplifying mechanism is provided in the brake
cylinder device, the configuration is not limited to the exemplary configuration
described in the second embodiment, and various modifications may be made to the
configuration of the force amplifying mechanism. For example, it is also possible to
adopt a configuration in which the force amplifying mechanism includes a receiving
member fixed to the guide tube, the pivot member is provided so as to be threaded into
the thread formed on the outer circumferential face of the receiving member, and the
receiving member moves in the braking direction by pivoting of the pivot member in a
predetermined direction of rotation. Furthermore, the configuration of the force
amplifying mechanism is not limited to the one in which two receiving members,
namely the first receiving member and the second receiving member, are provided as
the receiving members to the amplifying mechanism, and it is possible to adopt a
configuration of the force amplifying mechanism provided with only one receiving
member.
Industrial Applicability
[0147] The present invention is widely applicable to a brake cylinder device including
a clearance adjustment mechanism for automatically adjusting a clearance up to a
brake operating position in a brake-released state, and a disc brake device including
the brake cylinder device.
Descriptions of Reference Numerals
[0148] 2 Brake cylinder device
20 Cylinder body

21 Brake output portion
22 Piston
23 Piston spring
24 Threaded shaft
25 Guide tube
26 Pusher spring
27 Clutch nut
28 Front stopper
29 First clutch
30 Adjustment stopper
31 Adjustment spring
32 Second clutch

CLAIMS
1. A brake cylinder device comprising:
a cylinder body having a hollow interior;
a piston that defines a pressure chamber inside the cylinder body and to
which a biasing force generated by a piston spring is transmitted, the piston moving
relative to the cylinder body against the biasing force of the piston spring by supply of
pressure fluid to the pressure chamber;
a brake output portion that is provided so as to be movable together with the
piston or provided so as to be movable via a force amplifying mechanism for amplifying
a force generated in the piston as a result of movement of the piston, the brake output
portion being movable in a braking direction in which it projects from the cylinder
body and an anti-braking direction in which it approaches the cylinder body;
a threaded shaft that is connected to the brake output portion and has a
thread formed on an outer circumference thereof
a guide tube that is attached to the piston or the force amplifying mechanism
and accommodates the threaded shaft thereinside;
a pusher spring disposed so as to be capable of biasing the threaded shaft
toward the braking direction to the guide tube or the piston;
a clutch nut for threadably engaging with a tip of the threaded shaft disposed
on the brake output portion side with respect to the cylinder body;
a front stopper disposed so as to be capable of coming into contact with the
clutch nut on a front side, which is the brake output portion side with respect to the
clutch nut such that a movement of the clutch nut with respect to the guide tube is
restricted, and biasing the clutch nut and the threaded shaft in the anti-braking
direction together with a movement of the guide tube in the anti-braking direction;

a first clutch disposed so as to be capable of coming into contact with the
clutch nut via a predetermined interval from the front stopper on a rear side, which is
a side opposite to the brake output portion side with respect to the clutch nut;
an adjustment stopper that is disposed so as to be movable relative to the
clutch nut and the guide tube along the axial direction of the threaded shaft and whose
movable range is restricted with respect to the cylinder body;
a second clutch to which the adjustment stopper is fixed, and that is disposed
so as to be capable of coming into contact with the clutch nut on the rear side; and
an adjustment spring that is in contact with or connected to the adjustment
stopper or the second clutch at a first end thereof and is capable of biasing the clutch
nut toward the anti-braking direction.
2. The brake cylinder device according to claim 1,
wherein the threaded shaft has a hollow interior formed so as to be open
toward a side opposite to the brake output portion, and
the pusher spring biases the clutch nut threadably engaged with the threaded
shaft toward the front stopper by biasing the threaded shaft from inside.
3. The brake cylinder device according to claim 2,
further comprising a pusher spring guide that is formed as a shaft-like portion
provided so as to be movable together with the guide tube and is inserted inside the
pusher spring provided as a coil-shaped spring to restrict deformation of the pusher
spring in the buckling direction,
wherein the pusher spring guide is disposed such that a tip thereof is slidable
on the inside of the threaded shaft.

4. The brake cylinder device according to any one of claims 1 to 3,
wherein the front stopper and the first clutch are provided as separate unitary
members, and are each fixed to the guide tube.
5. The brake cylinder device according to claim 4,
wherein at least one of the front stopper and the first clutch is fixed to an
inner circumference of the guide tube by threaded coupling.
6. The brake cylinder device according to any one of claims 1 to 5,
further comprising an adjustment sleeve that is provided as a tubular
member disposed around the threaded shaft and having flexibility; and is biased
toward the anti-braking direction by a second end of the adjustment spring whose first
end is in contact with or connected to the adjustment stopper or the second clutch,
wherein the clutch nut and the adjustment sleeve are configured integrally by
engagement of an engaging portion formed on the adjustment sleeve with an engaged
portion formed on the clutch nut.
7. The brake cylinder device according to claim 6,
wherein the engaging portion of the adjustment sleeve engages from inside
with the engaged portion formed on an inner circumference of the clutch nut, and
a clearance formed between an inner circumference of the adjustment sleeve
and a top of a ridge of the threaded shaft has a smaller dimension in the radial
direction of the adjustment sleeve than a dimension, in the radial direction of the
adjustment sleeve, of indented portions of the engaging portion and the engaged

portion that are fitted together.
8. The brake cylinder device according to claim 7,
wherein the adjustment spring is disposed so as to bias, at the second end
thereof, a spring receiver attached to the adjustment sleeve, and
the spring receiver is disposed such that a clearance formed between the outer
circumference of the spring receiver and the inner circumference of the guide tube has
a dimension in the radial direction of the guide tube that is substantially zero, or is
disposed such that the outer circumference of the spring receiver and the inner
circumference of the guide tube are in sliding contact.
9. The brake cylinder device according to claim 8, wherein the spring receiver
includes a bearing.
10. The brake cylinder device according to any one of claims 1 to 9,
further comprising a spring stopper that restricts, to a predetermined amount
or less, the amount of displacement of the adjustment spring due to elastic
deformation caused by relative displacement of a second end of the adjustment spring
with respect to the first end thereof that is in contact with or connected to the
adjustment stopper or the second clutch.
11. The brake cylinder device according to any one of claims 1 to 10,
wherein teeth capable of engaging the second clutch with the clutch nut are
formed on at least one of a surface of the second clutch that faces the clutch nut and a
surface of the clutch nut that faces the second clutch.

12. The brake cylinder device according to any one of claims 1 to 11,
wherein the threaded shaft is provided, at a tip thereof, with an operation
engaging portion capable of engaging with an operation tool, and is disposed such that
the tip passes through the brake output portion and faces outward,
an engagement mechanism is further provided that is disposed on the outer
circumference of the tip of the threaded shaft and engages the threaded shaft with the
brake output portion, and
the engagement mechanism includes an outer circumferential engaging
portion that has engaging teeth capable of engaging with the brake output portion and
is fixed to the outer circumference of the threaded shaft, and an engaging spring that
biases the outer circumferential engaging portion toward the braking direction so as to
engage the engaging teeth with the brake output portion.
13. A disc brake device comprising: the brake cylinder device according to any one
of claims 1 to 12; and a caliper body that is equipped with the brake cylinder device
and is attached to a vehicle so as to.be displaceable relative to the vehicle in the
direction of an axle,
wherein operation of the brake cylinder device causes a disc on the axle side to
be sandwiched by a pair of brake pads attached to the caliper body, thereby generating
braking force.