CROSS REFERENCE TO RELATED APPLICATION
[0001]
The present invention is an application for claiming the
right of priority on the basis of the Japanese Patent Application
No. 2006-326859 (filed on December 4, 2006) and No. 2007-124917
(filed on May 9, 2007).
BACKGROUND OF THE INVENTION
1 Field of the Invention
[0002]
The present invention relates to a brake cylinder provided
with a push rod for actuating a brake device for vehicles and
capable of automatically adjusting the projected length of the
push rod from a cylinder main body when the brakes are in operation,
and in particular relates to a brake cylinder desirable for
railway vehicles.
2 Description of Related Art
[0003]
Regarding this type of a clearance adjusting device of
a brake cylinder, Patent Document 1 (Japanese Published Examined
Patent Application No. H06-67725 (claim 1, Fig. 2) has disclosed
1A

a constitution which is provided with an output piston having
inside the cylinder a push rod connected to a brake shoe for
braking a wheel tread and a friction ring assembly body
constituted so as to increase a friction/sliding resistance
with the inner face of the cylinder by sandwiching one elastic
ring with two circular plates to expand radially outward. In
Patent Document 1, when the brake shoe shows wear during brake
operation, the output piston and the friction ring assembly
body move according to an amount of the wear thereof, whereas
the friction ring assembly body does not move due to a greater
sliding resistance when the brakes are loosened. As a result,
a clearance is secured between the brake shoe and the wheel
tread.
[0004]
Patent Document 1 has also disclosed that two circular
plates are jointed via a stretching screw, and when a desired
sliding resistance value is not obtained due to the wear on
the outer circumference of an elastic ring, the stretching screw
is tightened to adjust the sliding resistance value.
[0005]
However, in the above-described constitution of Patent
Document 1, a problem is posed that when a cylinder in which
the push rod is adjusted for the projected length is returned
2

to an initial state, a substantial force must be imparted to
the cylinder against the frictional force of the friction ring
assembly body to result in increased labor for returning the
cylinder. Further, it is considered that after the tightened
stretching screw is loosened to reduce a frictional force, the
cylinder is returned to an initial state. However, this
requires readjustment of the frictional force of the stretching
screw, thus making the operation complicated.
SUMMARY OF THE INVENTION
[0006]
The present invention has been made in view of the above
circumstances, an object of which is to provide a brake cylinder
capable of easily returning from a state in which the projected
length of a push rod is adjusted to an initial state.
[0007]
The present invention relates to a brake cylinder provided
with a push rod for actuating a brake device for vehicles and
capable of adjusting the projected length of the push rod from
a cylinder main body when the brakes are in operation. Then,
the brake cylinder of the present invention has the following
several features for attaining the above object. In other words,
the brake cylinder of the present invention is provided with
3

the following features solely or in an appropriate combination
of them.
[0008]
A first feature of the brake cylinder of the present
invention for attaining the above object is a brake cylinder
used in a brake device for vehicles, which includes a piston
making a relative movement with respect to a cylinder main body
upon supply of pressure fluid, a shaft rod moving together with
the piston, a push rod attached to the shaft rod, and a projected
length adjusting means for adjusting on brake operation the
projected length of the push rod from the cylinder main body
in a direction in which the piston moves at the time of releasing
the brakes, wherein the push rod is formed in a cylindrical
shape so as to have a shaft hole extending parallel with a
direction in which the piston moves, with a female thread made
at least partially on the inner face of the shaft hole, and
the shaft rod, for which a male thread screwed with the female
thread is made at least partially on the outer face, is screwed
into the shaft hole and provided with an engaging portion which
can be engaged with a rotational-force imparting means for
imparting an axial rotational force from outside.
[0009]
According to this constitution, with the rotation of the
4

push rod being restricted, the rotational-force imparting means
such as a wrench is used to rotate the shaft rod axially via
the engaging portion, by which the push rod can be moved parallel
with a direction in which the piston moves with respect to the
shaft rod. Thereby, the projected length in a direction in
which the piston moves is adjusted by the projected length
adjusting means, making it possible to displace the push rod
retained at a predetermined position with a smaller force.
Therefore, it is possible to easily return from a state at which
the projected length of the push rod is adjusted to an initial
state.
[0010]
Further, a second feature of the brake cylinder of the
present invention is that which further includes a connection
member attached at the leading end of the push rod for connecting
the brake mechanism of a brake device for vehicles with the
push rod and the rotational-force imparting means, wherein the
shaft rod is formed so as to have at the center of the shaft
a central hole extending parallel with a direction in which
the piston moves, and the rotational-force imparting means is
equipped with a rod-like portion fitted into the central hole
and a rotation operating portion supported so as to rotate freely
with respect to the connection member for transmitting to the
5

rod-like portion an axial rotational force imparted from outside,
and engaged with the engaging portion via the rod-like portion.
[0011]
According to this constitution, the rotation operating
portion supported to the connection member so as to rotate freely
is operated for rotation, thereby the shaft rod is rotated
axially via the rod-like portion fitted into the central hole
of the shaft rod and the engaging portion, and the push rod
can be moved with respect to the shaft rod parallel with a
direction in which the piston moves. Then, since the
rotational-force imparting means having the rotation operating
portion and the rod-like portion is provided at the brake
cylinder, it is not necessary to separately provide the
rotational-force imparting means to be engaged with the engaging
portion of the shaft rod, for example, a wrench, when the
proj ected length of the push rod is returned to an initial state.
It is, therefore, possible to make an easy return from a state
that the projected length of the push rod has been adjusted
to an initial state more simply and quickly.
[0012]
Further, a third feature of the brake cylinder of the
present invention is that in which the rotational-force
impartingmeans is further provided with a cylindrical lidmember
6

which, having an engaging hole with which the rod-like portion
is engaged in a penetrating manner and formed in a cylindrical
shape, is engaged with the engaging portion installed at the
leading end of the shaft rod in a projected direction of the
push rod in such a state as to cover thereon.
[0013]
According to this constitution, the cylindrical lidmember
having the engaging hole with which the rod-like portion is
engaged in a penetrating manner and formed in a cylindrical
shape is engaged with the engaging portion installed at the
leading end of the shaft rod in such a state as to cover thereon,
thereby, eliminated is the necessity for constituting the
engaging portion on the central hole of the shaft rod. Thus,
a round hole may be used as the central hole to result in decreased
labor for processing. Therefore, a constitution in which the
rotational-force imparting means installed on the brake
cylinder is engaged with the engaging portion of the shaft rod
via the rod-like portion can be realized by a simple mechanism.
[0014]
Further, a fourth feature of the brake cylinder of the
present invention is that in which the central hole is formed
so as to have an inner face which is engaged with the rod-like
portion and provided as the engaging portion.
7

[0015]
According to this constitution, the central hole of the
shaft rod is formed so as to have the inner face which is engaged
with the rod-like portion, thereby eliminated is the necessity
for separately providing a member having an engaging portion
to save assembly labor. Therefore, a constitution in which
the rotational-force imparting means installed on the brake
cylinder is engaged with the engaging portion of the shaft rod
via the rod-like portion can be realized by a simple mechanism.
[0016]
Further, a fifth feature of the brake cylinder of the
present invention is that in which the engaging portion is
provided at the leading end of the shaft rod in a projected
direction of the push rod.
[0017]
According to this constitution, it is possible to perform
an operation of rotating the shaft rod by partially inserting
the rotational-force imparting means from the leading end side
of the push rod in the projected direction. In this instance,
it is also possible to perform the adjusting operation even
where other in-vehicle devices are arranged on the cylinder
main body of the brake cylinder. Further, when the brakes are
released, since the push rod is retained in a state that it
8

is retracted into the cylinder main body, secured is a space
on the side on which the push rod is projected. Therefore,
the space is utilized to perform the adjusting operation.
[0018]
Further, a sixth feature of the brake cylinder of the
present invention is that which further includes a connection
member attached to the leading end of the push rod for connecting
the brake mechanism of the brake device for vehicles with the
push rod, wherein an opening portion opened toward the engaging
portion from outside is formed on the connection member and
a lid portion capable of opening and closing the opening portion
is attached thereto.
[0019]
According to this constitution, the rotational-force
imparting means is partially inserted from the opening portion
of the connection member, thus making it possible to rotate
the shaft portion via the engaging portion. It is, thereby,
possible to return the projected length to an initial state
without disconnecting the brake mechanism from the brake
cylinder.
Further, since the lid portion is attached to the opening
portion, the opening portion is kept closed by the lid portion,
thereby making it possible to prevent dust and the like from
9

entering into the shaft hole of the push rod from outside via
the opening portion.
[0020]
Further, a seventh feature of the brake cylinder of the
present invention is that in which the projected length ad justing
means is provided with a guide member attached to the push rod
and also capable of moving together with the push rod, and the
guide member is attached to the push rod in such a manner that
a predetermined resistance force is applied when the push rod
makes a relative movement with respect to the guide member
parallel with a direction in which the piston moves.
[0021]
According to this constitution, the guide member and the
push rod are attached so as to have a predetermined resistance
force. Thus, if a force greater than a predetermined resistance
force, for example, a frictional force, is applied between the
guide member and the push rod, the push rod undergoes
displacement with respect to the guide member, thereby adjusting
the projected length from the cylinder main body when the brakes
are released. It is, therefore, possible to adjust the
projected length by a simple constitution.
Further, where the first feature is provided, in a state
that rotation of the push rod is restricted, the rotational-force
10

imparting means is used to rotate the shaft rod axially via
the engaging portion, by which the push rod can be displaced
parallel with a direction in which the piston moves. Therefore,
the shaft rod is rotated, thus making it possible to apply a
force greater than a predetermined resistance force between
the push rod and the guide member. Thereby, it is possible
to easily return from a state in which the projected length
of the push rod is adjusted to an initial state.
[0022]
Further, an eighth feature of the brake cylinder of the
present invention is that in which the pro j ected length ad j us ting
means is further provided with an indented face formed by
arranging repeatedly concavities and convexities on the outer
face of the push rod in a direction in which the push rod moves
and an elastic member arranged between the push rod and the
guide member, a space for opening at least the indented face
side is formed on the guidemember, the elasticmember is arranged
in the space, the elastic member is deformed and engaged with
the indented face, thereby connecting the guide member with
the push rod, and when a force greater than a predetermined
force is applied to the guide member, the elastic member is
deformed to go over the convex portion of the indented face,
by which the push rod undergoes displacement with respect to
11

the guide member.
[0023]
Conventionally, according to the constitution described
in Patent Document 1, for example, only a frictional force of
the inner circumferential face of a flat cylinder with the
surface of an elastic ring is used to generate a sliding
resistance, thereby the sliding resistance of the friction ring
assembly body is readily made unstable by the surface condition
and wear of the inner circumferential face of the cylinder or
the wear of the surface of the elastic ring. Further, adjustment
is made by using a stretching screw, which may complicate the
adjustment and management of the sliding resistance.
In this instance, according to the constitution having
the above eighth feature, the elastic member is deformed and
engaged (cut into), thus making it possible to stabilize a
frictional force or a binding force between the push rod and
the guide member. Thereby, it is possible to easily adjust
and manage the sliding resistance by a simple constitution.
BRIEF DESCRIPTION OF THE DRAWINGS
Other and further objects, features and advantages of
the invention will appear more fully from the following
description taken in connection with the accompanying drawings
12

in which:
Fig. 1 is an overall sectional view for illustrating a
state that the brakes are released in a brake cylinder of
Embodiment 1 of the present invention.
Fig. 2 is an overall sectional view for illustrating a
state that the brakes are in operation in the brake cylinder
given in Fig. 1.
Fig. 3 is an overall sectional view for illustrating a
state that the brakes are in operation in the brake cylinder
given in Fig. 1.
Fig. 4 is an overall sectional view of the brake cylinder
when a state given in Fig. 3 is shifted to a state that the
brakes are released.
Fig. 5 is an overall sectional view for illustrating a
state that the brakes are released in the brake cylinder.
Fig. 6 is an overall sectional view for illustrating a
state that the brakes are released in the brake cylinder of
Embodiment 2 of the present invention.
Fig. 7 is a left front view of a shaft rod in the brake
cylinder given in Fig. 6, a front view of the shaft rod illustrated
by the cutaway cross section, and a right side view of the shaft
rod.
Fig. 8 is a left side view and a front view of a rod member
13

of the brake cylinder given in Fig. 6.
Fig. 9 is a left side view of a manual tuning knob of
the brake cylinder given in Fig. 6 and a sectional view of the
manual tuning knob when viewed from the front face.
Fig. 10 is a left side view of a cylindrical lid member
of the brake cylinder given in Fig. 6 and a sectional view of
the cylindrical lid member when viewed from the front face.
Fig. 11 is an overall sectional view for illustrating
a state that the brakes are released in the brake cylinder of
Embodiment 3 of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0024]
Hereinafter, a description will be given for the best
mode for carrying out the present invention by referring to
the drawings.
[0025]
(Embodiment 1)
Fig. 1 is an overall sectional view for illustrating a
state that the brakes are not in operation in a brake cylinder
of Embodiment 1 of the present invention (brake released state) .
[0026]
The brake cylinder 1 of the present embodiment is used
14

in a disk-brake type brake device and actuated by supply of
compressed air (pressure fluid). A brake lever, which is a
part of a brake mechanism (not illustrated) , is installed
respectively on both ends of the brake cylinder 1 (on the side
of the cylinder main body and on the side of the push rod).
The push rod of the brake cylinder 1 is driven in a projected
direction to actuate a pair of brake levers, and a pair of brake
pads (brake shoes) installed at the leading end of the brake
levers are used to sandwich a circular-plate like brake disk
rotating in association with the rotation of wheels of a railway
vehicle, thereby generating a braking force.
[0027]
It is noted that the brake cylinder 1 is not restricted
to use in a disk-brake type brake device but may be used in
a tread-brake type brake device in which a brake shoe is attached
to the leading end of the push rod and the brake shoe is allowed
to be in contact with the tread of the wheel, thereby generating
a braking force.
[0028]
As illustrated in Fig. 1, the brake cylinder 1 is mainly
constituted with a cylinder main body 2 made up with a first
casing portion 21 and a second casing portion 22 to form an
inner space 2a, a piston 3 arranged in the inner space 2a, a
15

shaft rod 4 moving together with the piston 3, a cylindrical
push rod 5 attached to the shaft rod 4, and a projected length
adjusting means 6 for adjusting the projected length of the
push rod 5 from the cylinder main body 2.
[0029]
The first casing portion 21 is formed approximately in
a closed-cup shape (cylindrical shape), and the second casing
portion 22 is fixed by a bolt 23 so as to block the side on
which the first casing portion 21 is opened. Thereby, the inner
space 2a is formed. Further, the brake lever of the brake device
(not illustrated) is connected to the end of the first casing
portion 21.
[0030]
The piston 3 is arranged so as to divide the inner space
2a into two spaces, hermetically fitted into the inner
circumferential face of the first casing portion 21 and also
constituted so as to slide axially. One space of the inner
space 2a divided by the piston 3 is given as a pressure chamber
2b. A supply/discharge port 24 of compressed air formed on
the cylinder main body (first casing portion 21) is
communicatively connected to the pressure chamber 2b. A cup
packing 31 is adhered on the piston 3 in order to improve the
air tightness of the pressure chamber 2b.
16

[0031]
The base end portion of an outer cylinder 11 is installed
securely to the piston 3 arranged inside the first casing portion
21 via the flange plate 12 and the bolt 13. A head flange 14
is accommodated inside the base end of the outer cylinder 11.
A narrowed portion 15 in a tapered shape is formed on the inner
circumferential face of the shaft end of the outer cylinder
11. The narrowed portion 15 is able to press an inclined outer
peripheral edge of the head flange 14 to the leading end side
(to the side in which the push rod 5 advances). A press pin
16 is projected inwardly on the outer cylinder 11, and the leading
end of the press pin 1 is able to press the head flange 14 to
the base end side (to the side in which the push rod 5 retracts) .
[0032]
A male thread 41 is made on the outer circumferential
face of the shaft rod 4 and installed in a state that it is
screwed with a female thread 51 made in the vicinity of the
end of the pressure chamber 2b on the inner circumferential
face of the push rod 5. Further, the base end portion of the
shaft rod 4 located at the pressure chamber 2b side is attached
to the head flange 14, and a hexagonal-shape engaging portion
42, which corresponds to the head portion of a hexagonal bolt,
is provided at the other end of the shaft rod 4. The engaging
17

portion 42 may be formed integrally with the shaft rod 4 or
may be firmly fixed to the shaft rod 4 as a different member.
[0033]
The push rod 5 is formed in a cylindrical shape having
a shaft hole extending parallel with a direction in which the
piston 3 moves, and a female thread 51 is made in the vicinity
of the end of the inner circumferential face of the shaft hole,
which is on the pressure chamber 2b side. Further, an indented
face 52 formed by repeatedly arranging concavities and
convexities in a direction in which the push rod 5 moves is
provided on the outer circumferential face. It is noted that
a difference in height between the concavities and convexities
on the indented face 52 is, for example, about 0.3 mm, and the
indented face 52 is to constitute a part of the projected length
adjusting means 6.
[0034]
Further, a brake lever (not illustrated) , which is a part
of a brake mechanism of the brake device, is connected to the
leading end portion of the push rod 5 via the connection member
7, thus making it possible to transmit a driving force of the
brake cylinder 1 to the brake mechanism. It is noted that the
connection member 7 and the push rod 5 are fixed by a pin or
the like for regulating a relative axial rotation.
18

[0035]
An opening portion 7a which is opened to the engaging
portion 42 from outside is formed on the connection member 7
at the leading end of the push rod 5. The opening portion 7a
is formed in a tapered shape so as to reduce the diameter toward
the push rod 5, for which a female thread is made on the inner
circumference. A lid portion 8 for which a male thread to be
screwed with the female thread is made on the outer circumference
is screwed up into the opening portion 7a in a removable manner,
thus making it possible to open and close the opening.
[0036]
Further, a flexible bellows-like cover 25 for dust
prevention is installed between the push rod 5 and the second
casing portion 22 in such a manner as to cover the opening portion
of an insertion hole 22a formed at the end of the second casing
portion 22 opposite the first casing portion 21.
[0037]
The projected length adjusting means 6 is attached to
the push rod 5 and constituted with a guide member 61 movable
together with the push rod 5, an indented face 52, which is
an outer face of the push rod 5 and an O-ring (elastic member)
62 arranged between the push rod 5 and the guide member 61.
It is noted that in the present embodiment, an O-ring with a
19

diameter of about 5 mm and a substantially circular cross section
is used as the elastic member due to the fact that it is readily
available and relatively high in dimensional accuracy. However,
an elastic member mainly made of rubber or the like and having
an oval or a rectangular cross section may be used.
[0038]
A guide member 61 is formed in a cylindrical shape and
supported outside the shaft rod 4 so as to rotate freely via
a thrust bearing (a bearing) 17. Then, the guide member 61
is provided with a stepped shaft hole for allowing the push
rod 5 to be inserted, wherein an O-ring accommodating space
61a is formed at a site of the shaft hole which is formed to
have a larger diameter. The O-ring accommodating space 61a
is formed between the bottom of the larger diameter hole (stepped
portion) 61c and a stopper ring 63 fitted into the opening end
of the larger diameter hole, with the inner side (the side facing
the indented face 52 of the push rod 5) being opened.
[0039]
The construction is made in such a manner that a plurality
(four) of O-rings 62 are arranged side by side in an axial
direction in the O-ring accommodating space 61a, and a back-up
ring 64 is arranged at both ends of each of the O-rings 62 (between
adjacent O-rings 62). Positions of the bottom 61c and the
20

stopper ring 63 are established in relation with the width of
the O-ring 62 in such a manner that the O-ring 62 undergoes
an elastic deformation as it is crushed to some extent in an
axial direction between the bottom 61c of the larger diameter
hole and the stopper ring 63. Thereby, the O-ring 62 is expanded
to the inner circumference side and consequently engaged with
the indented face 52 on the outer circumferential face of the
push rod 5. Thus, a predetermined resistance force is to be
applied when the push rod 5 makes a relative movement with respect
to the guide member 61 parallel with a direction in which the
piston 3 moves.
[0040]
A rotation-stopping bolt 26 is screwed and installed into
the second casing portion 22 of the cylinder main body 2, and
the leading end portion thereof is inserted into a long hole
11a formed on the outer cylinder 11 and a long-hole like groove
61b formed on the guide member 61. As a result, the outer
cylinder 11 and the guide member 61 are stopped for rotation.
It is noted that the long hole 11a and the groove 61b are formed
so that the longitudinal direction thereof is parallel with
a direction in which piston 3 moves and the bolt 26 is allowed
to move inside the long hole 11a and the groove 61b in association
with the brake operation.
21

[0041]
Further, a regulator 65 is projected radially from the
guide member 61, and the regulator 65 is inserted through the
long hole 11b formed on the outer cylinder 11. The long hole
11b is formed in such a manner that the longitudinal direction
thereof is parallel with a direction in which the piston 3 moves.
On the other hand, a stroke adjusting bolt 66 is screwed and
installed into the second casing portion 22, and when the guide
member 61 moves by a predetermined stroke to the advancement
side, the regulator 65 is in contact with the leading end of
the stroke adjusting bolt 66, thereby regulating a further
movement of the guide member 61 to the advancement side. It
is noted that the stroke adjusting bolt 66 is rotated, thereby
adjusting the position of the leading end.
[0042]
A return spring 27 for urging the piston 3 in a retracting
direction is interposed between the second casing portion 22
and the piston 3. Further, an urging spring 28 is interposed
between the head flange 14 and the guide member 61.
[0043]
According to the above-described constitution,
compressed air is supplied to a supply/discharge port 24 in
a state as shown in Fig. 1 in which the brakes are not in operation,
22

thereby the piston 3 is pushed in the direction indicated by
the arrow A1 in the drawing against the return spring 27. As
a result, the outer cylinder 11 fixed thereto is moved in the
direction indicated by the arrow Al in the drawing. Then, a
narrowed portion 15 formed on the inner circumferential face
at the base end portion of the outer cylinder 11 pushes the
outer edge of the head flange 14, by which the head flange 14
is also moved in the direction indicated by the arrow Al in
the drawing, and the push rod 5 connected to the shaft rod 4
is also moved in the direction indicated by the arrow Al in
the drawing. Fig. 2 shows a state that the push rod 5 is moved
(a state that the regulator 65 is moved to a position in contact
with the stroke adjusting bolt 66) . In this instance, it is
noted that the head flange 14 and the shaft rod 4 are not rotated
but simply pushed by the outer cylinder 11. Thus, the push
rod 5 (in association with the outer cylinder 11 and the guide
member 61) is pushed in the direction indicated by the arrow
Al in the drawing and advanced therein, thereby actuating the
brake device.
[0044]
Then, when compressed air is discharged from the
supply/discharge port 24, the piston 3 is pushed by the return
spring 27 in the direction indicated by the arrow A2 in the
23

drawing. Therefore, the outer cylinder 11 is pulled in the
direction indicated by the arrow A2 in the drawing. Thus, the
head flange 14 is pushed by the press pin 16, and the shaft
rod 4 and the push rod 5 connected thereto are also pulled in
the direction indicated by the arrow A2 in the drawing and
retracted. As a result, the brakes are returned to an inactive
state as in Fig. 1.
[0045]
On the other hand, when the braking face of the brake
pad shows wear, a stroke of the push rod 5 necessary for actuating
the brakes is increased to result in a greater stroke of the
guide member 61 connected to the push rod 5 via an 0-ring 62.
When the stroke exceeds a stroke specified by the stroke
adjusting bolt 66, the regulator 65 comes in contact with the
leading end of the stroke adjusting bolt 66, thereby giving
a great returning force to the guide member 61. Therefore,
after the regulator 65 is in contact with the leading end of
the stroke adjusting bolt 66, the 0-ring 62 is deformed to go
over a convex portion of the indented face 52, by which the
push rod 5 is deviated (displaced) with respect to the guide
member 61 by only an amount corresponding to a further stroke
of the push rod 5. In other words, the piston 3 is moved in
a projected direction (to the right in the drawing) from a state
24

as given in Fig. 1 in which the brakes are released, thereby,
the regulator 65 is in contact with the leading end of the stroke
adjusting bolt 66 as shown in Fig. 2. The piston 3 is further
moved in the projected direction, thereby, as shown in Fig.
3, the shaft rod 4, the push rod 5 and others are displaced
in the projected direction, with only the guide member 61 being
left. It is noted that in Fig. 3, in order to easily explain
the displacement of the push rod 5 with respect to the guide
member 61, a relative movement amount is described in an enlarged
manner. In most cases, since a wear amount of the brake pad
for each braking operation is quite small, a displacement amount
of the push rod 5 for one time is accordingly small to an extent
of a clearance between convex portions on the indented face
52.
[0046]
Where compressed air is discharged from the
supply/discharge port 24 to release the brakes after a relative
displacement takes place between the push rod 5 and the guide
member 61, the piston 3 is returned by the return spring 27
in the direction indicated by the arrow A2 in the drawing, and
the head flange 14 is pushed in the direction indicated by the
arrow A2 in the drawing by the press pin 16 of the outer cylinder
11 which is pulled thereby. Then, the flange 14 is rotated
25

together with the shaft rod 4, the shaft rod 4 is consequently
taken out from the push rod 5 and the above-described
displacement of the push rod 5 with respect to the guide member
61 in the advancing direction is absorbed by a screw movement.
Fig. 4 shows a state which is returned from a state given in
Fig. 3 to a state as given in Fig. 1 in which the brakes are
released. As shown in Fig. 4, the push rod 5 is consequently
projected to the advancing direction by the above-described
deviation. It is noted that in Fig. 4, the arrow X indicates
an amount of the deviation compared with an initial state given
in Fig. 1 (initial position Xo) .
[0047]
As described so far, the push rod 5 is adjusted for the
projected length, and the brake device for vehicles can be
subsequently actuated by a normal stroke of the push rod 5.
[0048]
Fig. 5 is a view for illustrating a state that the brakes
are released when the push rod 5 is adjusted for the projected
length in a case where a prolonged use has resulted in a
substantial wear of a brake pad. As compared with a state given
in Fig. 1 that the brakes are released, the push rod 5 is moved
substantially in the projected direction and projected greatly
from the cylinder main body 2.
26

[0049]
In a state given in Fig. 5, where a brake pad now in use
is exchanged for a new brake pad which is the same as that before
wear, it is necessary to return a position of the push rod 5
in a state that the brakes are released to an initial position
before being adjusted by the projected length adjusting means
6.
[0050]
In the brake cylinder 1 of the present- embodiment, the
lid portion 8 screwed up to the opening portion 7a of the
connection member 7 is removed, by which it is possible to insert,
for example, a socket 91 (rotational-force imparting means)
engaged with the engaging portion 42 and an extension bar 92
connected serially to the socket 91 (rotational-force imparting
means) into the engaging portion 42 from outside via the opening
portion 7a.
[0051]
The socket 91 is attached to the engaging portion 42 and
rotated in a predetermined direction by a ratchet handle wrench
93 and others (rotational-force imparting means) via the
extension bar 92, thus making it possible to transmit a great
rotational force to the engaging portion 42. As a result, an
axial rotational force acts on the shaft rod 4 via the engaging
27

portion 42, and the push rod 5 restricted for axial rotation
by the connection member 7 is to receive a force in a drawing-in
direction due to the action of screws (the male thread 41 and
the female thread 51) . Thereby, the push rod 5 can be displaced
in the drawing-in direction against a resistance force received
from the O-ring 62 arranged between the push rod 5 and the guide
member 61.
[0052]
It is noted that the shaft rod 4 is reversely rotated,
thereby making it possible to displace the push rod 5 in the
projected direction. Further, the screws (the male thread 41
and the female thread 51) are adjusted for the pitch, for example,
the pitch is made smaller, by which the push rod 5 can be displaced
parallel with a direction in which the piston 3 moves by a smaller
rotational force.
[0053]
As described so far, the brake cylinder 1 of the present
embodiment includes a piston 3 which makes a relative movement
with respect to the cylinder main body 2 on supply of pressure
fluid, a shaft rod 4 which moves together with the piston 3,
a push rod 5 attached to the shaft rod 4, and a projected length
adjusting means 6 for adjusting on brake operation the projected
length of the push rod 5 from the cylinder main body 2 in a
28

direction in which the piston 3 moves at the time of releasing
the brakes, wherein the push rod 5 is formed in a cylindrical
shape so as to have a shaft hole extending parallel with a
direction in which the piston 3 moves, with a female thread
51 made at least partially on the inner face of the shaft hole,
and the shaft rod 4, for which a male thread screwed with the
female thread 51 is made at least partially on the outer face,
is screwed into the shaft hole and provided with an engaging
portion 42 which can be engaged with a rotational-force imparting
means such as the socket 91 for imparting an axial rotational
force from outside.
[0054]
According to this constitution, in a state that the push
rod 5 is restricted for rotation by the connection member 7
or others, a ratchet handle wrench 93 or the like connected
to the socket 91 via the extension bar 92 is used to axially
rotate the shaft rod 4 via the engaging portion 42, thus making
it possible to move the push rod 5 with respect to the shaft
rod 4 parallel with a direction in which the piston 3 moves.
Thereby, the projected length in a direction in which the piston
3 moves is adjusted by the projected length adjusting means
6, by which the push rod 5 retained at a predetermined position
can be displaced by a smaller force. Therefore, it is possible
29

to easily return from a state that the push rod 5 is adjusted
for the projected length to an initial state.
[0055]
Further, since the brake cylinder is constituted in such
a manner that the female thread 51 is made only at a part of
the vicinity of the end which is on the pressure chamber 2b
side on the inner circumferential face of the shaft hole formed
on the push rod 5, the screws can be made smaller in rotational
resistance, thereby rotating the shaft rod 4 by a smaller force.
[0056]
Further, the projected length adjusting means 6 is
provided with a guide member 61 attached to the push rod 5 and
movable together with the push rod 5, wherein the guide member
61 is attached to the push rod 5 so that a predetermined resistance
force can act when the push rod 5 makes a relative movement
with respect to the guide member 61 parallel with a direction
in which the piston 3 moves.
[0057]
According to this constitution, the guide member 61 is
attached to the push rod 5 in such a manner that a predetermined
resistance force is imparted to the push rod 5 from the guide
member 61 when the push rod 5 makes a relative movement with
respect to the guide member 61. Therefore, when a force
30

exceeding a predetermined resistance force is applied between
the guide member 61 and the push rod 5, the push rod 5 is displaced
with respect to the guide member 61, thus adj usting the pro j ected
length from the cylinder main body 2 when the brakes are released.
Thereby, it is possible to adjust the projected length by a
simple constitution.
[0058]
Further, in a state that the push rod 5 is restricted
for rotation, the shaft rod 4 is axially rotated via the engaging
portion 42, by which the push rod 5 can be displaced parallel
with a direction in which the piston 3 moves. Therefore, the
shaft rod 4 is rotated, thereby making it possible to apply
a force exceeding a predetermined resistance force between the
push rod 5 and the guide member 61. Thereby, it is possible
to easily return from a state that the push rod 5 is adjusted
for the projected length to an initial state.
[0059]
Further, the projected length adjusting means 6 is further
provided with an indented face 52 formed by repeatedly arranging
concavities and convexities on the outer face of the push rod
5 in a direction in which the push rod 5 moves and an O-ring
62 arranged between the push rod 5 and the guide member 61,
wherein a space 61a for opening at least the indented face 52
31

side is formed on the guide member 61, the O-ring 62 is arranged
in the space 61a, the O-ring 62 is deformed and engaged with
the indented face 52, thereby the guide member 61 is connected
to the push rod 5, and also a force exceeding a predetermined
force is applied to the guide member 61, thereby the O-ring
62 is deformed to go over the convex portion of the indented
face 52, and the push rod 5 is displaced with respect to the
guide member 61.
[0060]
According to this constitution, since the O-ring 62 is
deformed and engaged therewith (cut into), it is possible to
stabilize a frictional force or a binding force between the
push rod 5 and the guide member 61. Thereby, it is possible
to easily adjust and manage a sliding resistance by a simple
constitution.
[0061]
Further, since the O-ring 62 is used as an elastic member,
it can be engaged with (cut into) the concave portion of the
indented face 52 more easily than a case where an elastic member
is, for example, rectangular in cross section, thus making it
possible to stabilize a frictional force or a binding force.
[0062]
Further, since a plurality of the O-rings 62 are provided,
32

a frictional force or a binding force between the push rod 5
and the guide member 61 can be stabilized to a greater extent
than a case where the O-ring is used solely.
[0063]
Further, since a backup ring 64 is provided between a
plurality of the O-rings 62, a case is prevented where the O-ring
62 enters into an adjacent O-ring 62 or goes over outside the
adjacent O-ring 62, thus making it possible to join the push
rod 5 and the guide member 61 reliably by a frictional force.
[0064]
Still further, since the engaging portion 42 is attached
to the leading end of the shaft rod 4 in a projected direction
of the push rod 5, a part of the rotational-force imparting
means such as the socket 91 and the extension bar 92 is inserted
from the leading end side of the push rod 5 in the projected
direction, thereby making it possible to perform an operation
of rotating the shaft rod 4. In this instance, adjustments
can be made, even if other in-vehicle devices are arranged on
the cylinder main body 2 of the brake cylinder 1. Further,
since the push rod 5 is retained, with the rod retracted into
the cylinder main body 2 when the brakes are released, a space
is secured on the side at which the push rod 5 is projected.
Therefore, it is possible to make adjustments by using this
33

space.
[0065]
A connection member 7 is further provided, which is
attached to the leading end of the push rod 5 to connect the
brake mechanism of the brake device for vehicles with the push
rod 5. An opening portion 7a opened toward the engaging portion
42 from outside is formed on the connection member 7, and a
lid portion 8 for opening and closing the opening portion 7a
is also attached thereto.
[0066]
According to this constitution, a part of the
rotational-force imparting means such as the socket 91 and the
extension bar 92 is inserted from the opening portion 7a of
the connection member 7, thus making it possible to rotate the
shaft rod 4 via the engaging portion 42. Thereby, it is possible
to return the projected length to an initial state without
disconnecting the brake mechanism from the brake cylinder 1.
Further, since the lid portion 8 is attached to the opening
portion 7a, the opening portion 7a is kept closed by using the
lid portion 8, thus making it possible to prevent dust and the
like from entering into the shaft hole of the push rod 5 from
outside via the opening portion 7a.
[0067]
34

(Embodiment 2)
Next, a description will be given for a brake cylinder
of Embodiment 2 in the present invention. Fig. 6 is an overall
sectional view for illustrating a state that the brakes are
not in operation in a brake cylinder 101 of Embodiment 2. The
brake cylinder 101 illustrated in Fig. 6 is that which is used
in a disk-type brake device as with the brake cylinder 1 of
Embodiment 1 and constituted so as to operate similarly by having
the same constituents as those of the brake cylinder 1. In
other words, as with the brake cylinder 1, the brake cylinder
101 is mainly constituted with a cylinder main body 2, a piston
3, a shaft rod 112, a push rod 5, a projected length adjusting
means 6 and a connection member 7. (It is noted that the
corresponding cross section in Fig. 6 is laterally reversed
as compared with that in Fig. 1.) However, the brake cylinder
101 is different from the brake cylinder 1 in a rotational-force
imparting means 111 which is provided as its own constitution
and in some constitutions of a shaft rod 112. In the following
description, it is noted that constituents constituted and
operated similarly in the brake cylinder 101 as with the brake
cylinder 1 will be given the same symbols in Fig. 6 as those
used in Fig. 1 and are omitted for explanation.
[0068]
35

Fig. 7 is a view for illustrating the shaft rod 112. Fig.
7(b) is a front view of the shaft rod which is indicated by
the cutaway cross section. Fig. 7(a) is a left side view of
Fig. 7(b). Fig. 7(c) is a right side view of Fig. 7(b). As
illustrated in Fig. 6 and Fig. 7, the shaft rod 112 is formed
so as to have at the center of the shaft a central hole 112a
extending parallel with a direction in which the piston 3 moves.
The central hole 112a is formed as a round hole so that the
cross section perpendicular to the axial longitudinal direction
is circular and also formed to be opened at one end portion
112b arranged to oppose the connection member 7. Further, a
male thread portion 112c screwed with the cylindrical lidmember
115 of the rotational-force imparting means 111 to be described
later is made on the outer circumference of the end portion
112b. The male thread portion 112c is made as a screw, the
rotational direction of which is reverse to that of the male
thread 41 made on the outer circumference of the body of the
shaft rod 4, and constituted as an engaging portion of the present
embodiment which is engaged with the rotational-force imparting
means 111.
[0069]
As illustrated in Fig. 6, the rotational-force imparting
means 111 is constituted with a rod member (rod-like portion)
36

113, a manual tuning knob (rotation operating portion) 114,
a cylindrical lid member 115, and a pin 116. The
rotational-force imparting means 111, which is different from
that of Embodiment 1, is constituted so as to be assembled into
the brake cylinder 1 as a constituent, thus eliminating the
necessity for providing the means separately.
[0070]
Fig. 8 is a view for illustrating the rod member 113
constituting the rod-like portion of the present embodiment.
Fig. 8(b) is a front view and Fig. 8(a) is a left side view.
As illustrated in Fig. 6 and Fig. 8, the rod member 113 is formed
in a rod shape extending on the same cross section, and fitted
into the central hole 112a from an opening formed at the end
portion 112b of the shaft rod 112. Then, a cross section
perpendicular to the longitudinal direction of the rod member
113 is given an external shape which is formed by arranging
a pair of flat portions 113a, 113a opposing each other at a
parallel position and a pair of arc portions 113b, 113b opposing
each other in four directions. Any circle at which a pair of
the arc portions 113b, 113b are arranged is made slightly smaller
in diameter than that of the central hole 112a of the shaft
rod 112. Further, the rod member 113 is provided at one end
portion arranged to project from the shaft rod 112 with a pin
37

hole 113c formed in a penetrating manner so as to extend
perpendicularly to the longitudinal direction. A pin 116 is
to be inserted through the pin hole 113c. A manual tuning knob
114 is to be connected to the rod member 113 via the pin 116
inserted through the pin hole 113c. In the present embodiment,
it is noted that the manual tuning knob (rotation operating
portion) 114 is formed in separation from the rod member
(rod-like portion) 113 and connected by the pin 116. However,
the present embodiment may be provided in a different manner.
For example, the manual tuning knob 114 may be formed integrally
with the rod member 113.
[0071]
Fig. 9 is a view for illustrating the manual tuning knob
114. Fig. 9(b) is a sectional view when viewed from the front
face. Fig. 9(a) is a left side view. As illustrated in Fig.
6 and Fig. 9, a knob portion 114a having a hexagonal external
shape installed at one end portion and an opening 114b installed
at the other end portion are formed on the manual tuning knob
114. One end portion of the rod member 113 is to be inserted
through the opening 114b. Further, a pair of pin supporting
holes 114c, 114c penetrating laterally via the opening 114b
are formed on the manual tuning knob 114. Then, the pin 116
is fitted into a pair of pin supporting holes 114c, 114c and
38

the pin hole 113c in a state that one end portion of the rod
member 113 is kept inserted through the opening 114b, by which
the manual tuning knob 114 is connected with the rod member
113 via the pin 116. Further, the manual tuning knob 114 is
formed in such amanner that an outer peripheral edge 114dbetween
the knob portion 114a of one end portion and the opening 114b
of the other end portion is given a circular external shape.
Then, the manual tuning knob 114 is supported so as to rotate
freely at a rotational supporting hole 117 formed at the center
thereof in a penetrating manner with respect to the connection
member 7 on the outer peripheral edge 114d, and the knob portion
114a is arranged so as to project outward from the connection
member 7 . Therefore, the knob portion 114a is manually operated
for rotation, by which the manual tuning knob 114 is rotated
with respect to the connection member 7, and the rod member
113 connected to the manual tuning knob 114 via the pin 116
is also rotated. In other words, the manual tuning knob 114
is to constitute a rotation operating portion of the present
embodiment which is supported to the connection member 7 so
as to rotate freely, thus transmitting an axial rotational force
imparted from outside to the rod member 113. It is noted that
the manual tuning knob 114 is not necessarily operated manually
but can be operated for rotation by using a tool such as a wrench.
39

[0072]
Fig. 10 is a view for illustrating the cylindrical lid
member 115. Fig. 10(b) is a sectional view when viewed from
the front face, and Fig. 10(a) is a left side view. As
illustrated in Fig. 6 and Fig. 10, the cylindrical lid member
115 is formed in a cylindrical shape. An engaging hole 115a
formed in an inner circumferential shape corresponding to the
outer circumferential shape of the rod member 113 so that the
rod member 113 is penetrated and engaged is opened and formed
at one end portion, whereas the shaft-rod inserting hole 115b
through which one end portion 112b of the shaft rod 112 is inserted
is opened and formed at the other end portion. A female thread
portion 115c which is screwed with the male thread portion 112c
of the shaft rod 112, is formed at the inner wall portion of
the shaft-rod inserting hole 115b. Therefore, one end portion
112b of the shaft rod 112 is screwed into the cylindrical lid
member 115, by which the male thread portion 112c is screwed
with the female thread portion 115c in a direction reverse to
that in which the male thread 41 of the shaft rod 112 is screwed
with the female thread 51 of the push rod 5. As described above,
the cylindrical lid member 115 is engaged with the rod member
113 at the engaging hole 115a and also engaged with the male
thread portion 112c, which is an engaging portion provided at
40

the leading end of the shaft rod 112 (in the projected direction
of the push rod 5) in a state so as to cover thereon. Thereby,
the rotational-force imparting means 11 is to be engaged with
the male thread portion (engaging portion) 112c via the rod
member 113.
[0073]
The above-described brake cylinder 101 performs a braking
operation similar to that of the brake cylinder 1 of Embodiment
1 upon supply of compressed air from a supply/discharge port
24, and performs a brake releasing operation similar to that
of the brake cylinder 1 upon discharge of compressed air from
the supply/discharge port 24. Then, when the braking face of
a brake pad shows wear, the push rod 5 is ad j us ted for the pro j ected
length by the projected length adjusting means 6 in a similar
manner as done in the brake cylinder 1. However, in the brake
cylinder 101, where the brake pad now in use is exchanged for
a new brake pad which is the same as that before wear, eliminated
is the necessity for separately providing the rotational-force
imparting means of Embodiment 1 such as the socket 91, the
extension bar 92, or the ratchet handle wrench 95. Thus, the
rotational-force imparting means 111 installed on the brake
cylinder 101 can be used to return a position of the push rod
5 in a state that the brakes are released to an initial position
41

before being adjusted by the projected length adjusting means
6.
[0074]
Where the brake pad of the brake cylinder 101 is exchanged,
the knob portion 114a of the manual tuning knob 114 exposed
so as to project outward from the connection member 7 is operated
for rotation in a predetermined direction, by which the rod
member 113 is rotated with respect to the connection member
7 via the pin 116, together with the manual tuning knob 114.
Then, in association with the rotation of the rod member 113,
the cylindrical lid member 115, which is engaged with the rod
member 113 at the engaging hole 115a, is rotated, thereby an
axial rotational force is to act on the shaft rod 112 which
is engaged with the cylindrical lid member 115 through threaded
connection of the female thread portion 115c with the male thread
portion 112c. As a result, a force in a drawing-in direction
resulting from the action of screws (the male thread 41 and
the female thread 51) is to act on the push rod 5 restricted
for axial rotation by the connection member 7. Thereby, the
push rod 5 can be displaced in the drawing-in direction against
a resistance force received from the O-ring 62 arranged between
the push rod 5 and the guide member 61.
[0075]
42

As described so far, according to the brake cylinder 101
of the present embodiment, the manual tuning knob (rotation
operating portion) 114 supported so as to rotate freely with
respect to the connection member 7 is operated for rotation,
by which the shaft rod 112 is axially rotated via the rod member
(rod-like portion) 113 fitted into the central hole 112a of
the shaft rod 112 and the male thread portion (engaging portion)
112c, thus making it possible to move the push rod 5 with respect
to the shaft rod 112 parallel with a direction in which the
piston 3 moves. Then, since the rotational-force imparting
means 111 having the manual tuning knob 114 and the rod member
113 is provided at the brake cylinder 101, eliminated is the
necessity for separately providing a rotational-force
imparting means which is engaged with an engaging portion of
the shaft rod 112. Thus, it is possible to make an easy return
from a state that the push rod 5 is adjusted for the projected
length to an initial state more simply and quickly.
[0076]
Further, according to the brake cylinder 101, the
cylindrical lid member 115 formed in a cylindrical shape and
having the engaging hole 115a with which the rod member 113
is engaged in a penetrating manner is engaged with the male
thread portion (engaging portion) 112c installed at the leading
43

end of the shaft rod 112 so as to cover thereon. Thereby, it
is possible to realize a constitution in which the
rotational-force imparting means 111 installed on the brake
cylinder 101 is engaged with an engaging portion of the shaft
rod 112 via the rod member 113 by using a simple mechanism.
[0077]
(Embodiment 3)
Next, a description will be given for a brake cylinder
of Embodiment 3 in the present invention. Fig. 11 is an overall
sectional view for illustrating a state that the brakes are
not in operation in a brake cylinder 102 of Embodiment 3. The
brake cylinder 102 given in Fig. 11 is that which is used in
a disk-type brake device as with the brake cylinder 1 of
Embodiment 1 and constituted so as to operate similarly by having
the same constituents as those of the brake cylinder 1. In
other words, as with the brake cylinder 1, the brake cylinder
102 is mainly constituted with a cylinder main body 2, a piston
3, a shaft rod 119, a push rod 5, a projected length adjusting
means 6 and a connection member 7. (It is noted that the
corresponding cross section in Fig. 11 is laterally reversed
as compared with that in Fig. 1.) However, the brake cylinder
102 is different from the brake cylinder 1 in a rotational-force
imparting means 118 which is provided as its own constitution
44

and in some constitutions of the shaft rod 119, as with the
brake cylinder 101 of Embodiment 2. In the following
description, it is noted that constituents constituted and
operated similarly in the brake cylinder 102 as with the brake
cylinder 1 will be given the same symbols in Fig. 11 as those
used in Fig. 1 and omitted for explanation.
[0078]
As illustrated in the sectional view of Fig. 11, the shaft
rod 119 is formed so as to have at the center of the shaft a
central hole 119a extending parallel with a direction in which
the piston 3 moves. The central hole 119a is formed as a hole
with a hexagonal cross section which is perpendicular to the
axial longitudinal direction, and also formed in such a manner
as to be opened at one end portion arranged to oppose the
connection member 7. As will be described later, the central
hole 119a is constituted as an engaging portion of the present
embodiment which is engaged with the rotational-force imparting
means 118.
[0079]
As illustrated in the sectional view of Fig. 11, the
rotational-force imparting means 118 is constituted so as to
have a rod-like portion 120 and a rotation operating portion
121. The rod-like portion 120 and the rotation operating
45

portion 121 are formed integrally.
[0080]
The rod-like portion 120 is formed in a rod shape and
made up with a root portion 120a and a hexagonal cross-section
portion 120b. The root portion 120a is formed as a round-rod
portion, one side of which is integrally formed with the rotation
operating portion 121, and the other side of which is formed
so as to continue to the hexagonal cross-section portion 120b.
Further, the hexagonal cross-section portion 120b is formed
so that the cross section perpendicular to the longitudinal
direction is hexagonal. Then, the rod-like portion 120 is given
in such a manner that the hexagonal cross-section portion 120b
is fitted into the central hole 119a from an opening formed
at the end portion of the shaft rod 119. Since the central
hole 119a of the shaft rod 119 is formed as a hole with a hexagonal
cross section so as to correspond to the external shape of the
hexagonal cross-section portion 120b, the rod-like portion 120
fitted into the central hole 119a is to be engaged with the
central hole 119a on an attempt to rotate in a circumferential
direction. In other words, the central hole 119a is formed
so as to have an inner face to be engaged with the rod-like
portion 120, thereby it is provided as an engaging portion of
the present embodiment.
46

[0081]
The rotation operating portion 121 is constituted with
a knob portion 121a and a rotating head portion 121b, and the
knob portion 121a formed so as to give a hexagonal external
shape is installed securely to the rotating head portion 121b.
Further, the rotating head portion 121b is formed so as to give
a circular external shape on the periphery, and formed integrally
with the rod-like portion 120 on the side opposite that at which
the knob portion 121a is installed securely. Then, the rotation
operating portion 121 is supported so as to rotate freely at
the rotational supporting hole 117 formed in a penetratingmanner
at the central portion with respect to the connection member
7 on an outer peripheral edge around the rotating head portion
121b, and the knob portion 121a is arranged in a state that
it is projected outward from the connection member 7 . Therefore,
the knob portion 121a is manually operated for rotation, by
which the rotation operating portion 121 is rotated with respect
to the connection member 7, and the rod-like portion 120 is
also rotated together with the rotation operating portion 121.
In other words, the rotation operating portion 121 is supported
so as to rotate freely with respect to the connection member
7 and also constituted so as to transmit an axial rotational
force imparted from outside to the rod-like portion 120. Then,
47

the rotation operating portion 121 is to be engaged with the
central hole 119a, which is an engaging portion of the shaft
rod 119, via the rod-like portion 120. It is noted that the
rotation operating portion 121 is not necessarily operated
manually but may be operated for rotation by using a tool such
as a wrench.
[0082]
The above-described brake cylinder 102 performs a braking
operation similar to that of the brake cylinder 1 of Embodiment
1 upon supply of compressed air from a supply/discharge port
24. It also performs a brake releasing operation similar to
that of the brake cylinder 1 upon discharge of compressed air
from the supply/discharge port 24 . Then, when the braking face
of a brake pad shows wear, the push rod 5 is adjusted for the
projected length by the projected length adjusting means 6 in
a similar manner as done in the brake cylinder 1. However,
in the brake cylinder 102, where the brake pad now in use is
exchanged for a new brake pad which is the same as that before
wear, eliminated is the necessity for separately providing the
rotational-force imparting means of Embodiment 1 such as the
socket 91 and the extension bar 92 . Thus, the rotational-force
imparting means 118 installed on the brake cylinder 102 can
be used to return a position of the push rod 5 in a state that
48

the brakes are released to an initial position before being
adjusted by the projected length adjusting means 6.
[0083]
Where the brake pad of the brake cylinder 102 is exchanged,
the knob portion 121a of the rotation operating portion 121
exposed so as to project outward from the connection member
7 is operated for rotation in a predetermined direction, by
which the rod-like portion 120 is rotated with respect to the
connection member 7 together with the rotation operating portion
121. Then, since the inner face of the central hole 119a on
the shaft rod 119 into which the rod-like portion 120 is fitted
is engaged with the rod-like portion 120, an axial rotational
force is to act on the shaft rod 119 with the rotation of the
rod-like portion 120. As a result, a force in a drawing-in
direction resulting from the action of screws (the male thread
41 and the female thread 51) is to act on the push rod 5 restricted
for axial rotation by the connection member 7. Thereby, the
push rod 5 can be displaced in the drawing-in direction against
a resistance force received from the 0-ring 62 arranged between
the push rod 5 and the guide member 61.
[0084]
As described so far, according to the brake cylinder 102
of the present embodiment, the rotation operating portion 121
49

supported so as to rotate freely with respect to the connection
member 7 is operated for rotation, by which the rod-like portion
120 fitted into the central hole 119a of the shaft rod 119 is
rotated axially, thus making it possible to move the push rod
5 with respect to the shaft rod 119 parallel with a direction
in which the piston 3 moves. Then, since the rotational-force
imparting means 118 having the rotation operating portion 121
and the rod-like portion 120 is provided at the brake cylinder
102, eliminated is the necessity for separately providing a
rotational-force imparting means which is engaged with an
engaging portion of the shaft rod 119. Thus, it is possible
to make an easy return from a state that the push rod 5 is adjusted
for the projected length to an initial state more simply and
quickly.
[0085]
Further, according to the brake cylinder 102, the central
hole 119a of the shaft rod 119 is formed so as to have an inner
face which is engaged with the rod-like portion 120 . Therefore,
it is possible to realize a constitution in which the
rotational-force imparting means 118 installed on the brake
cylinder 102 is engaged with an engaging portion of the shaft
rod 119 via the rod-like portion 120 by a simple mechanism.
[0086]
50

A description has been given so far for Embodiment 1 to
Embodiment 3 of the present invention. However, the present
invention is not limited to the above embodiments and may be
modified and carried out in various ways within the scope of
the claims. For example, the present invention may be modified
as follows and carried out.
[0087]
In the above embodiments, the cylinder device used as
a driving source of the brake device is an air cylinder device
which is driven by air pressure. However, the present invention
is not limited thereto but a cylinder device or the like driven
by oil pressure may be used.
[0088]
Further, the present invention is not limited to a case
where the indented face 52 is formed on the outer circumferential
face of the push rod 5. The present invention may be constituted
in such a manner that the outer circumferential face is made
flat, and a frictional force which the push rod 5 receives from
an elastic member such as the O-ring 62 is used to impart a
predetermined resistance force. In this instance, it is
possible to easily fabricate the outer circumferential face
of the push rod 5, thus resulting in reduction in manufacturing
costs. Further, the present invention is not limited to a case
51

where concavities and convexities are repeatedly arranged on
the surface of the push rod 5 in a direction in which the push
rod 5 moves, thereby forming the indented face 52. The present
invention is also applicable to a case where the push rod 5
is subjected to surface treatment such as blast treatment,
thereby adjusting a frictional force.
[0089]
Still further, the present invention is not limited to
a case where the push rod 5 is connected to the guide member
61 via an elastic member but applicable to a case where the
push rod is connected to the guide member by a mechanical
constitution in which a predetermined resistance force is
applied when the push rod moves parallel with the moving
direction of a piston with respect to a guide member, for example,
the push rod is moved with respect to the guide member while
a gear mechanism having a predetermined rotational resistance
is driven.
[0090]
It is noted that Fig. 1 to Fig. 11 used in explaining
the embodiments of the present invention are described as
accurately as engineering drawings, with each of the
constitutions made accurate in ratio.
[0091]
52

While this invention has been described in conjunction
with the specific embodiments outlined above, it is evident
that many alternatives, modifications and variations will be
apparent to those skilled in the art. Accordingly, the
preferred embodiments of the invention as set forth above are
intended to be illustrative, not limiting. Various changes
may be made without departing from the spirit and scope of the
invention as defined in the following claims.
53

WE CLAIM:
[Claim 1]
A brake cylinder used in a brake device for vehicles
comprising:
a piston which makes a relative movement with respect
to a cylinder main body upon supply of pressure fluid;
a shaft rod moving together with the piston;
a push rod attached to the shaft rod; and
a projected length adjusting means for adjusting on brake
operation the projected length of the push rod from the cylinder
main body in a direction in which the piston moves at the time
of releasing the brakes, wherein
the push rod is formed in a cylindrical shape so as to
have a shaft hole extending parallel with a direction in which
the piston moves, with a female thread made at least partially
on the inner face of the shaft hole, and
the shaft rod, for which a male thread screwed with the
female thread is made at least partially on the outer face,
is screwed into the shaft hole and provided with an engaging
portion which can be engaged with a rotational-force imparting
means for imparting an axial rotational force from outside.
[Claim 2]
The brake cylinder as set forth in claim 1, further
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comprising:
a connection member attached to the leading end of the
push rod for connecting the brake mechanism of the brake device
for vehicles with the push rod; and
the rotational-force imparting means, wherein
the shaft rod is formed so as to have at the center of
the shaft a central hole extending parallel with a direction
in which the piston moves, and
the rotational-force imparting means is equipped with
a rod-like portion fitted into the central hole and a rotation
operating portion supported so as to rotate freely with respect
to the connection member for transmitting to the rod-like portion
an axial rotational force imparted from outside, and engaged
with the engaging portion via the rod-like portion.
[Claim 3]
The brake cylinder as set forth in claim 2, wherein the
rotational-force imparting means is further provided with a
cylindrical lid member which, having an engaging hole with which
the rod-like portion is engaged in a penetrating manner and
formed in a cylindrical shape, is engaged with the engaging
portion installed at the leading end of the shaft rod in a
projected direction of the push rod in such a state as to cover
thereon.
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[Claim 4]
The brake cylinder as set forth in claim 2, wherein the
central hole is formed so as to have an inner face which is
engaged with the rod-like portion and thereby provided as the
engaging portion.
[Claim 5]
The brake cylinder as set forth in claim 1, wherein the
engaging portion is provided at the leading end of the shaft
rod in the projected direction of the push rod.
[Claim 6]
The brake cylinder as set forth in claim 5, further
comprising a connection member attached to the leading end of
the push rod for connecting the brake mechanism of the brake
device for vehicles with the push rod, wherein
an opening portion opened toward the engaging portion
from outside is formed on the connection member and a lid portion
capable of opening and closing the opening portion is attached
thereto.
[Claim 7]
The brake cylinder as set forth in any one of claim 1
to claim 6, wherein
the projected length adjusting means is provided with
a guide member attached to the push rod and also capable of
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moving together with the push rod, and
the guide member is attached to the push rod in such a
manner that a predetermined resistance force is applied when
the push rod makes a relative movement with respect to the guide
member parallel with a direction in which the piston moves.
[Claim 8]
The brake cylinder as set forth in claim 7, wherein
the projected length adjusting means is further provided
with
an indented face formed by arranging repeatedly
concavities and convexities on the outer face of the push rod
in a direction in which the push rod moves and
an elastic member arranged between the push rod and the
guide member,
a space for opening at least the indented face side is
formed on the guide member, the elastic member is arranged in
the space,
the elastic member is deformed and engaged with the
indented face, thereby connecting the guide member with the
push rod, and
when a force greater than a predetermined force is applied to
the guide member, the elastic member is deformed to go over
the convex portion of the indented face, by which the push rod
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undergoes displacement with respect to the guide member.


Dated this 21st day of November, 2007
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The brake cylinder of the present invention is a brake
cylinder used in a brake device for vehicles, and includes a
piston making a relative movement with respect to a cylinder
main body, a shaft rod moving together with the piston, a push
rod attached to the shaft rod, and a projected length adjusting
means for adjusting the projected length of the push rod from
the cylinder main body on brake operation. The push rod is
formed in a cylindrical shape so as to have a shaft hole extending
parallel with a direction in which the piston moves, with a
female thread made at least partially on the inner face of the
shaft hole, and the shaft rod, for which a male thread screwed
with the female thread is made at least partially on the outer
face, is screwed into the shaft hole and provided with an engaging
portion which can be engaged with a rotational-force imparting
means for imparting an axial rotational force from outside.