Technical Field
[0001]
The present invention relates to a suspension device.
Background Art
[0002]
Conventionally, among various types of suspension
devices for suspension of an axle from a frame, a
suspension device with a plurality of layered leaf springs,
which is simple in structure, less expensive and highly
strong and durable, has been extensively used for a truck
or other vehicle.
[0003]
In such suspension device, it is a matter of course
to mount the plural layered leaf springs so as to enable
positioning of the axle even if any of the springs breaks,
which however disadvantageously results in increases in
weight of the vehicle. Thus, a suspension device has been
studied which comprises a single leaf spring for weight
saving.
[0004]
There exists, for example, the following Patent
Literature 1 as prior art document relating to this kind
of leaf suspension.
-2-
Citation List
Patent Literature
[0005]
[Patent Literature 1] JP 6-173986A
Summary of Invention
Technical Problems
[0006]
In the case of a single leaf spring used and if the
spring breaks at a position behind an axle-suspending
intermediate portion of the spring, a rear portion of the
spring behind the break position of the spring may tilt
downward into contact with a ground and thus a vehicle
body may lift up in pole-vault manner using the rear
portion of the spring as support into movement of wheels
away from the ground. It is feared that, for example in
the case of front wheels being moved away, loss of
steering and/or braking may be caused; in the case of rear
wheels being moved away, loss of braking and/or nontransmittal
of a driving force to the ground may be caused.
[0007]
The invention was made in view of the above and has
its object to prevent a rear portion of a leaf spring from
tilting downward into contact with a ground even if the
spring breaks at a position behind an intermediate portion
-3-
of the spring.
Solution to Problems
[OOQ8]
The invention is directed to a suspension device in
which front and rear brackets are arranged on a side rail
ahead of and behind an axle, respectively, a single leaf
spring being pivoted at a front end thereof to the front
bracket and being pivoted at a rear end thereof to the
rear bracket through a shackle pivotally movable backward
and forward, said axle being suspended by an intermediate
portion of said leaf spring, characterized in that it
comprises first restriction means for restricting a rear
portion of said leaf spring from tilting downward upon
breakage of said leaf spring at a position behind the
intermediate portion of the spring and second restriction
means for restricting said shackle from pivotally moving
backward beyond a predetermined angle, said first
restriction means comprising a bush arranged at a
connection between said shackle and the rear end of said
leaf spring for integral rotation with the rear end of
said leaf spring and having projections for engagement
with said shackle at a predetermined rotary position.
[0009]
Thus, in this way, upon the breakage of the leaf
-4-
spring at the position behind the intermediate portion of
the spring, the shackle is restricted by the second
restriction means from pivotally moving backward beyond
the predetermined angle while the projections of the bush
as the first restriction means engage with the shackle at
the predetermined rotary position to be unable to rotate
further, thereby restricting the leaf spring from
pivotally moving downward beyond a predetermined angle, so
that there is no fear that the broken rear portion of the
leaf spring contacts the ground.
[0010]
The invention is also directed to a suspension device
in which front and rear brackets are arranged on a side
rail ahead of and behind an axle, respectively, a single
leaf spring being pivoted at a front end thereof to the
front bracket and being pivoted at a rear end thereof to
the rear bracket through a shackle pivotally movable
backward and forward, said axle being suspended by an
intermediate portion of said leaf spring, characterized in
that it comprises first restriction means for restricting
a rear portion of said leaf spring from tilting downward
upon breakage of said leaf spring at a position behind the
intermediate portion of the spring and second restriction
means for restricting said shackle from pivotally moving
backward beyond a predetermined angle, said first
-5-
restriction means comprising an engagement member fitted
over the rear end of said leaf spring for integral
rotation with the rear end of said leaf spring and having
a projection for engagement with said rear bracket at a
predetermined rotary position.
[0011]
Thus, in this way, upon the breakage of the leaf
spring at the position behind the intermediate portion of
the spring, the shackle is restricted by the second
restriction means from pivotally moving backward beyond
the predetermined angle while the projection of the
engagement member as the first restriction means engages
with the rear bracket at the predetermined rotary position
to be unable to rotate further, thereby restricting the
leaf spring from pivotally moving downward beyond a
predetermined angle, so that there is no fear that the
broken rear portion of the leaf spring contacts the ground.
[0012]
The invention is also directed to a suspension device
in which front and rear brackets are arranged on a side
rail ahead of and behind an axle, respectively, a single
leaf spring being pivoted at a front end thereof to the
front bracket and being pivoted at a rear end thereof to
the rear bracket through a shackle pivotally movable
backward and forward, said axle being suspended by an
-6-
intermediate portion of said leaf spring, characterized in
that it comprises first restriction means for restricting
a rear portion of said leaf spring from tilting downward
upon breakage of said leaf spring at a position.behind the
intermediate portion of the spring and second restriction
means for restricting said shackle from pivotally moving
backward beyond a predetermined angle, said first
restriction means comprising an eye formed by the rear end
of said leaf spring and rotatably wound around a
horizontal pin on a lower portion of the shackle, said eye
being tapered into reduced thickness toward a tip in a
winding direction so as to engage with said rear bracket
at a predetermined rotary position due to increase in
thickness.
[0013]
Thus, in this way, upon the breakage of the leaf
spring at the position behind the intermediate portion of
the spring, the shackle is restricted by the second
restriction means from pivotally moving backward beyond
the predetermined angle while the eye as the first
restriction means engages with the rear bracket at the
predetermined rotary position due to increase in thickness
to be unable to rotate further, thereby restricting the
leaf spring from pivotally moving downward beyond a
predetermined angle, so that there is no fear that the
-7-
broken rear portion of the leaf spring contacts the ground.
Advantageous Effects of Invention
[0014]
According to the suspension device of the invention
mentioned in the above, excellent effects and advantages
can be obtained. Even if a leaf spring breaks at a
position behind an intermediate portion of the spring, the
leaf spring can be restricted from pivotally moving
downward beyond a predetermined angle and a rear portion
of the leaf spring can be preliminarily prevented from
tilting downward into contact with a ground. Thus, lift
of a vehicle body in pole-vault manner using the rear
portion of the leaf spring as support can be reliably
averted to substantially improve the safety.
Brief Description of Drawings
[0015]
Fig. 1 is a side view showing a first embodiment of a
suspension device according to the invention;
Fig. 2 is an enlarged view showing important parts in
Fig. 1;
Fig. 3 is a perspective view showing particulars of a
bush in Fig. 1;
Fig. 4 is a side view showing a leaf spring in Fig. 1
-8-
e upon breakage;
Fig. 5 is a side view showing a second embodiment of
the suspension device according to the invention;
Fig. 6 is a side .view showing a leaf spring in Fig.
upon breakage;
Fig. 7 is a side view showing a third embodiment of
the suspension device according to the invention; and
Fig. 8 is a side view showing a leaf spring in Fig.
upon breakage.
Description of Embodiments
[0016]
Embodiments of the invention will be described in
conjunction with the drawings.
[0017]
5.
7
Figs. 1-4 show a first embodiment of a suspension
device according to the invention. As shown in Fig. 1, in
this embodiment, front and rear brackets 3 and 4 are
arranged on a side rail 1 ahead of and behind an axle 2,
respectively. A single leaf spring 5 is pivoted at a
front end thereof to the front bracket 3 and is pivoted at
a rear end thereof to the rear bra9ket 4 through a shackle
6 which in turn is pivotally movable backward and forward.
The axle 2 is suspended by an intermediate portion of the
leaf spring 5.
-9-
[0018]
More specifically, the axle 2 is connected to a lower
surface of the intermediate portion of the leaf spring 5
through U-shaped bolts 7. The front end of the leaf
spring 5 is wound upwardly into an eye 8 which is
rotatably wound around a horizontal pin 9 of the front
bracket 3 on the side rail 1. Just like the front end of
the leaf spring 5, the rear end of the spring is wound
upwardly into an eye 10 which is rotatably wound around
a horizontal pin 11 of a lower portion of the shackle 6
which in turn is pivotally movable backward and forward
about a horizontal pin 11' of the rear bracket 4 on the
side rail 1.
[0019]
As shown in Fig. 2 in enlarged scale, for winding of
the eye 10 of the rear end of the leaf spring 5 around a
horizontal pin 11 of a lower portion of the shackle 6, a
bush 12 is intervened between the pin 11 and the eye 10.
In the embodiment, an outer cylinder 12a of the bush 12 is
circumferentially formed with a pair of ~rejections 12b
(see Fig. 3) protruding oppositely and laterally of a
vehicle (perpendicularly to Fig. 2 plane). Upon breakage
of the leaf spring 5 at a position behind an intermediate
portion of the spring, the bush 12 functions as first
restriction means for restriction of the rear portion of
-10-
the leaf spring 5 from tilting downward.
[0020]
Specifically, upon the breakage of the leaf spring 5
at the position behind the intermediate portion of .the
spring, the bush 12 rotates together with the eye 10
constituting the rear end of the leaf spring 5 and the
projection 12b engages with the shackle 6 at a
predetermined rotary position, thereby restricting the
rear portion of the leaf spring 5 from tilting downward.
[0021]
As second restriction means for restriction of the
shackle 6 from pivotally moving backward beyond a
predetermined angle, a length of retainer pawl 13
protrudes backward from an upper end of the shackle 6.
Thus, even if upon the breakage the shackle 6 tries to
pivotally move backward due to a load of the rear portion
of the leaf spring 5 applied, the retainer pawl 13 engages
with a step 4a of the rear bracket 4 to restrict the
shackle 6 from pivotally moving backward beyond the
predetermined angle.
[0022]
Here, Figs. 1 and 2 are illustrations where a truck
or other objective vehicle is in gross vehicle weight
condition. In such condition, the engagement of the
retainer pawl 13 of the shackle 6 with the step 4a of the
-11-
rear bracket 4 restricts the backward pivotal movement of
the shackle while the projections 12b of the bush 12 are
kept away from the shackle 6 with a required gap, such gas
remaining a little even in an empty vehicle weight
condition.
[0023]
Specifically, the rear end of the leaf spring 5
extends most backward when the spring is flattened in the
gross vehicle weight condition. Therefore, when the
engagement of the retainer pawl 13 of the shackle 6 with
the step 4a of the rear bracket 4 restricts the backward
pivotal movement of the shackle in the gross vehicle
weight condition, functions of the shackle 6 are not hurt.
Moreover, when the gap between the projections 12b and the
shackle 6 remains a little even in the empty vehicle
weight condition, the projections 12b can be caused not to
abut on the shackle 6 within a suspension stroke.
[0024]
In this regard, it is necessary to set the tilting
angle of the rear portion of the leaf spring 5 restricted
by the projections 12b of the bush 12 within an angle
range where the rear portion of the leaf spring 5 can be
surely prevented from contacting with the ground G even if
the leaf spring 5 breaks at a position just behind the
axle 2 and thus the rear portion of the spring has a
-12-
maximum length.
[0025]
With the suspension device thus constructed, upon the
breakage of the leaf spring 5 at the position behind the
intermediate portion of the spring as shown in Fig. 4, the
engagement of the retainer pawl 13 with the step 4a of the
rear bracket 4 restricts the shackle 6 from pivotally
moving backward beyond the predetermined angle while the
projections 12b of the bush 12 engage with the shackle 6
at the predetermined rotary position to unable to rotate
further, thereby restricting the leaf spring 5 from
tilting downward beyond the predetermined angle, so that
there is no fear that the broken rear portion of the leaf
spring 5 contacts the ground G.
[0026]
Thus, according to the above embodiment, even if the
leaf spring 5 breaks at the position behind the
intermediate portion of the spring, the leaf spring 5 can
be restricted from pivotally moving downward beyond the
predetermined angle and the rear portion of the leaf
spring 5 can be preliminarily prevented from tilting
downward into contact with the ground G, so that the lift
of the vehicle body in pole-vault manner using the rear
portion of the leaf spring 5 as support can be surely
averted to substantially improve the safety.
-13-
[0027]
Figs. 5 and 6 show a second embodiment of a
suspension device according to the invention. As shown in
Fig. 5, in this embodiment, in place of the bush 12 with
the projections 12b as the first restriction means in the
previous first embodiment, the first restriction means
comprises an engagement member 14 fitted over an outer
periphery of an eye 10 constituting the rear end of the
leaf spring 5 for integral rotation with the eye 10 and
having a projection 14a for engagement with the lower end
of the rear bracket 4 at a predetermined rotary position.
[0028]
Specifically, upon the breakage of the leaf spring 5
at a position behind the intermediate portion of the
spring, the engagement member 14 rotates integrally with
the eye 10 constituting the rear end of the leaf spring 5
and the projection 14a engages with a lower end of the
rear bracket 4 at the predetermined rotary position,
thereby restricting the rear portion of the leaf spring 5
from tilting downward.
[0029]
Also in the second embodiment, as the second
restriction means for restricting the shackle 6 from
pivotally moving backward beyond a predetermined angle, a
length of retainer pawl 13 protrudes backward from an
-14-
upper end of the shackle 6. Thus, even if upon the
breakage the shackle 6 tries to pivotally move backward
due to a load of the rear portion of the leaf spring 5
applied, the engagement of the retainer pawl 13 with the
step 4a of the rear bracket 4 restricts the shackle 6 from
pivotally moving backward beyond the predetermined angle.
[0030]
Fig. 5 is an illustration where a truck or other
objective vehicle is in the gross vehicle weight condition.
In such condition, the engagement of the retainer pawl 13
of the shackle 6 with the step 4a of the rear bracket 4
restricts pivotal movement of the shackle while the
projection 14a of the engagement member 14 is kept away
from the lower end of the rear bracket 4 with a required
gap, such gas remaining a little even in the empty vehicle
weight condition.
[0031]
Specifically, the rear end of the leaf spring 5
extends most backward when the spring is flattened in the
gross vehicle weight condition. Therefore, when the
engagement of the retainer pawl 13 of the shackle 6 with
the step 4a of the rear bracket 4 restricts the rearward
pivotal movement in the gross vehicle weight condition,
functions of the shackle 6 are not hurt. Moreover, when
the gap between the projection 14a and the rear end of the
-15-
rear bracket 4 remains a little even in the empty vehicle
weight condition, the projection 14a can be caused not to
abut on the lower end of the rear bracket 4 within a
suspension stroke.
[0032]
In this regard, it is necessary to set the tilting
angle of the rear portion of the leaf spring 5 restricted
by the projection 14a of the engagement member 14 within
an angle range where the rear portion of the leaf spring 5
can be surely prevented from contacting with the ground G
even if the leaf spring 5 breaks at a position just behind
the axle 2 and thus the rear portion of the spring has a
maximum length.
[0033]
With the suspension device thus constructed, upon the
breakage of the leaf spring 5 at the position behind the
intermediate portion of the spring as shown in Fig. 6, the
engagement of the retainer pawl 13 with the step 4a of the
rear bracket 4 restricts shackle 6 from pivotally moving
backward beyond the predetermined angle while the
projection 14a of the engagement member 14 engages with
the lower end of the rear bracket 4 at a predetermined
rotary position to be unable to rotate further, thereby
restricting the leaf spring 5 from pivotally moving
downward beyond the predetermined angle, so that there is
-16-
i
J
! 1
1
-!
~
1"
~
1
no fear that the broken rear portion of the leaf spring 5
contacts the ground G.
[0034]
Thusr also in such second embodiment, upon the
breakage of the leaf spring 5 at the position behind the
intermediate portion of the spring, the leaf spring 5 can
be restricted from tilting downward beyond the
predetermined angle and the rear portion of the leaf
spring 5 can be preliminarily prevented from tilting
downward into contact with the ground G, so that the lift
of the vehicle body in pole-vault manner using the rear
portion of the leaf spring 5 as support can be surely
averted to substantially improve the safety.
[0035]
Figs. 7 and 8 show a third embodiment of a suspension
device according to the invention. As shown in Figs. 7
and 8, in this embodiment, in place of the engagement
member 14 with the projection 14a as the first restriction
means in the previous second embodiment, the first
restriction means comprises an eye 10 formed by the rear
end of the leaf spring 5 and rotatably wound around a
horizontal pin 11 on the lower portion of the shackle 6,
the eye being tapered into reduced thickness toward a tip
in a winding direction so as to engage with the lower end
of the rear bracket 4 at the predetermined rotary position
-17-
l
~ • !
due to increase in thickness.
[0036]
Specifically, upon the breakage of the leaf spring 5
at a position behind the. intermediate portion of the
spring, the eye 10 constituting the rear end of the leaf
spring 5 rotates and engages with the lower end of the
rear bracket 4 at a predetermined rotary position due to
increase in thickness, thereby restricting the rear
portion of the leaf spring 5 from tilting downward.
[0037]
Moreover, also in this third embodiment, as the
second restriction means for restricting the shackle 6
from pivotally moving backward beyond the predetermined
angle, a length of retainer pawl 13 protrudes backward
from an upper end of the shackle 6. Thus, even if upon
the breakage the shackle 6 tries to pivotally move
backward due to a load of the rear portion of the leaf
spring 5 applied, the engagement of the retainer pawl 13
with the step 4a of the rear bracket 4 restricts the
shackle 6 from pivotally moving backward beyond the
predetermined angle.
[0038]
Here, Fig. 7 is an illustration where a truck or
other objective vehicle is in gross vehicle weight
condition. In such condition, the engagement of the
-18-
l
retainer pawl 13 of the shackle 6 with the step 4a of the
rear bracket 4 restricts the backward pivotal movement
while the eye 10 is kept away from a lower end of the rear
bracket 4 with a required gap, such gap remaining a little
even in an empty vehicle weight condition.
[0039]
Specifically, the rear end of the leaf spring 5
extends most backward when the spring is flattened in the
gross vehicle weight condition. Therefore, when the
engagement of the retainer pawl 13 of the shackle 6 with
the step 4a of the rear bracket 4 restricts the backward
pivotal movement in the gross vehicle weight condition,
functions of the shackle 6 are not hurt. Moreover, when
the gap between the eye 10 and the lower end of the rear
bracket 4 remains a little even in the empty vehicle
weight condition, the eye 10 can be caused not to abut on
the lower end of the rear bracket 4 within a suspension
stroke.
[0040]
In this regard, it is necessary to set the tilting
angle of the leaf spring 5 restricted by thickness of the
eye 10 within an angle range where the rear portion of the
leaf spring 5 can be surely prevented from contacting with
the ground G even if the leaf spring 5 breaks at a
position just behind the axle 2 and thus the rear portion
-19-
1
of the spring has a maximum length.
[0041]
With the suspension device thus constructed, upon the
breakage of the leaf spring 5 at the position behind the
intermediate portion of the spring as shown in Fig. 8, the
engagement of the retainer pawl 13 with the step 4a of the
rear bracket 4 restricts the shackle 6 from pivotally
moving backward beyond the predetermined angle while the
eye 10 engages with the lower end of the rear bracket 4 at
the predetermined rotary position to be unable to rotate
further, thereby restricting the leaf spring 5 from
tilting downward beyond a predetermined angle, so that
there is no fear that the broken rear portion of the leaf
spring 5 contacts the ground G.
[0042]
Thus, also in such third embodiment, upon the
breakage of the leaf spring 5 at the position behind the
intermediate portion of the spring, the leaf spring 5 can
be restricted from tilting backward beyond the
predetermined angle and the rear portion of the leaf
spring 5 can be preliminarily prevented from tilting
backward into contact with the ground G, so that lift of
the vehicle body in pole-vault manner using the rear
portion of the leaf spring 5 as support can be surely
averted to substantially improve the safety.
-20-
[0043]
It is to be understood that a suspension device
according to the invention is not limited to the above
embodiments and that various changes and modifications may
be made without departing from the scope of the invention.
Reference Signs List
[0044]
1 side rail
2 axle
3 front bracket
4 rear bracket
5 leaf spring
6 shackle
10 eye (first restriction means)
11 horizontal pin
12 bush (first restriction means)
12b projection
13 retainer pawl (second restriction means)
14 engagement member (first restriction means)
14a projection
-21-

WE CLAIM:
1. A suspension device in which front and rear brackets
are arranged on a side rail ahead of and behind an axle,
respectively, a single leaf.spring being pivoted at a
front end thereof to the front bracket and being pivoted
at a rear end thereof to the rear bracket through a
shackle pivotally movable backward and forward, said axle
being suspended by an intermediate portion of said leaf
spring,
comprising first restriction means for restricting a
rear portion of said leaf spring from tilting downward
upon breakage of said leaf spring at a position behind the
intermediate portion of the spring and second restriction
means for restricting said shackle from pivotally moving
backward beyond a predetermined angle,
said first restriction means comprising a bush
arranged at a connection between said shackle and the rear
end of said leaf spring for integral rotation with the
rear end of said leaf spring and having projections for
engagement with said shackle at a predetermined rotary
position.
2. A suspension device in which front and rear brackets
are arranged on a side rail ahead of and behind an axle,
respectively, a single leaf spring being pivoted at a
-22-
^ front end thereof to the front bracket and being pivoted
at a rear end thereof to the rear bracket through a
shackle pivotally movable backward and forward, said axle
being, suspended by an intermediate portion of said leaf
spring,
comprising first restriction means for restricting a
rear portion of said leaf spring from tilting downward
upon breakage of said leaf spring at a position behind the
intermediate portion of the spring and second restriction
means for restricting said shackle from pivotally moving
backward beyond a predetermined angle,
said first restriction means comprising an engagement
member fitted over the rear end of said leaf spring for
integral rotation with the rear end of said leaf spring
and having a projection for engagement with said rear
bracket at a predetermined rotary position.
3. A suspension device in which front and rear brackets
are arranged on a side rail ahead of and behind an axle,
respectively, a single leaf spring being pivoted at a
front end thereof to the front bracket and being pivoted
at a rear end thereof to the rear bracket through a
shackle pivotally movable backward and forward, said axle
being suspended by an intermediate portion of said leaf
spring,
-23-
^ comprising first restriction means for restricting a
rear portion of said leaf spring from tilting downward
upon breakage of said leaf spring at a position behind the
intermediate portion of the spring and second restriction
means for restricting said shackle from pivotally moving backward beyond a predetermined angle,
said first restriction means comprising an eye formed by the rear end of said leaf spring and rotatably wound around a horizontal pin on a lower portion of the shackle, said eye being tapered into reduced thickness toward a tip in a winding direction so as to engage with said rear bracket at a predetermined rotary position due to increase in thickness.