JPH0718535Y2 - Tool for attaching and removing the return spring of a vehicle drum brake - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a return spring attaching / detaching tool for attaching / detaching a return spring stretched over a pair of brake shoes of a drum brake for an internal expansion vehicle.

[Conventional technology]

The pair of brake shoes arranged to face the back plate of the vehicle drum brake are constantly urged in the diameter reducing direction by a coiled return spring stretched between both webs. This return spring is attached and detached together with the brake shoe when installing or removing the brake shoe. In particular, the tool used for removing the return spring is only as simple as the one obtained by improving the conventional pliers. Therefore, a removal tool such as that disclosed in Japanese Utility Model Laid-Open No. 58-84872 has been proposed.

This removal tool is a tool in which a protruding piece-like spring engaging portion is projected to the side of the rotation support shaft near the tip of the rotation support shaft having a rotation bar handle fixed to the base end. Rotate the bar handle by inserting the tip of the rotation support shaft of the removal tool into the hooking hole of the tool and engaging the spring engaging part with the hook at the end of the return spring locked in the hooking hole. The return spring is removed from the brake shoe by removing the hook from the hook hole and moving the removal tool away from the web of the brake shoe.

[Problems to be solved by the device]

However, with such removal, a fairly large set load is set on the return spring when it is stretched, so at the same time as pulling out the tip of the rotation support shaft from the hook hole in the web, the removal tool reduces the return spring. The return spring may bounce due to sudden pulling in the direction, or the hook may disengage from the spring engaging portion, and the removal work must be performed carefully. Furthermore, this tool is for removal only, and it is extremely difficult to mount a return spring using this removal tool.

Therefore, an object of the present invention is to provide a tool for attaching / detaching a return spring of a vehicle drum brake, which enables easy and reliable removal and attachment of the return spring.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, the present invention hooks a hook at the end portion of a return spring stretched between a pair of brake shoe webs to a spring engagement portion provided on the tip side of a pivot shaft. In the return spring attaching / detaching tool of the vehicle drum brake for attaching / detaching the hook to / from the hooking hole of the web to attach / detach the return spring, the spring engaging portion is provided to the side of the rotation support shaft. A protrusion that projects to prevent the hook of the return spring from coming off and a pair of fitting recesses that hooks the hook on both sides of the base of the protrusion are formed, and at the tip of the rotation support shaft,
A pivot fulcrum pivot portion fitted in a guide hole formed in the web is provided in a protruding manner, and each length from the rotation fulcrum to the pair of fitting recesses is set to the hooking hole. And the distance between the guide hole and the guide hole is set to be substantially the same.

[Action]

In this return spring attaching / detaching tool, the pivot portion is fitted in the guide hole to erect the rotary support shaft on one of the webs. And when installing the return spring,
The other hook of the return spring is hooked in the hooking hole of the other web, and the one hook is hooked to the fitting recess of the pair of projecting piece bases on the side opposite to the return spring. The hooks hooked in the fitting recesses are prevented from coming off by the adjacent protrusions.

Next, the rotation support shaft is rotated in the direction of the hooking hole formed in one of the webs, the return spring is pulled, and the end of the hook is dropped into the hooking hole of the one web. After tensioning the return spring, the attachment / detachment tool is rotated in the contracting direction of the return spring to be removed.

When removing the return spring, fit the pivot part of the tool for attaching / detaching the return spring into the guide hole, insert the protrusion of the spring engaging part between the hook and the web, and temporarily turn the rotary support shaft into the return spring. Of the spring engaging portion, hook the hook in the fitting recess of the spring engaging portion, and further rotate the rotating support shaft in the extending direction.
While pulling up the return spring, pull up the hook from the retaining hole to the upper surface of the web, and then rotate the rotation support shaft in the contraction direction of the return spring to contract the return spring and to project the spring engagement part. Remove the piece from the hook.

〔Example〕

 An embodiment of the present invention will be described below with reference to the drawings.

In the figure, FIG. 1 shows a tool for attaching and detaching the return spring (hereinafter,
(Abbreviated as a detachable tool), perspective views, FIGS.
The drawings respectively show explanatory views of attaching and detaching the return spring of the drum brake using this attaching / detaching tool.

The attachment / detachment tool 1 includes a rotation support shaft 1a, a rotation bar handle 1b protruding from the base end of the support shaft 1a to both sides, and a rotation support shaft 1a.
A spring engaging portion 1c protruding laterally from the vicinity of the tip of
It is composed of a small-diameter pivot portion 1d protruding axially from the tip end surface of the rotation support shaft 1a.

The spring engaging portion 1c has a protruding piece at the center of the tip for retaining.
1e is projectingly provided, and a pair of fitting recesses are provided on both sides of the base of the projecting piece 1e.
1g and 1h are formed respectively. On the lower surface of the protrusion 1e,
The tapered surface 1f is formed so as to be thin toward the tip, and the fitting recesses 1g and 1h are formed by the same arcuate surface as the outer diameter of the wire used for the return spring 12 described later. The tip end surface of the pivot portion 1d is chamfered on a spherical surface so that the rotation support shaft 1a can be easily rotated.

Further, the fitting recesses 1g and 1h of the spring engaging portion 1c are set such that the respective lengths from the rotation support shaft 1a are substantially the same as the interval between the guide hole 22 and the latch hole 6d described later. .

The inner expansion type drum brake 2 shown in FIG. 2 to FIG.
It is a leading trailing type with a parking brake that is arranged on one of the rear wheels of a vehicle. A back brake plate 3 fixed to the vehicle body has a leading brake shoe 4 and a trailing brake shoe 5. It is arranged opposite.

The brake shoes 4,5 include an arcuate web 6a, a rim 6b fixed to the outer periphery of the web 6a, and a lining 6c attached to the rim 6b. , The shoe hold pin 7 and the shoe hold spring 8 elastically hold the back plate 3 and the web
One end of 6a is supported by an anchor 9 which is a pivotal fulcrum of the brake shoes 4, 5, and the other end on the expansion side is supported by pistons 11, 11 projecting from both ends of a wheel cylinder 10.

Coil-shaped return springs 12 and 13 are stretched between the webs 6a and 6a on the inside of the wheel cylinder 10 and the outside of the anchor 9, respectively. The return spring 12 on the expansion side urges the brake shoes 4, 5 in the diameter reducing direction, and the return spring 13 on the rotation fulcrum side securely holds one end of the brake shoes 4, 5 on the anchor 9. I have a job.

In the vicinity of the return spring 12 on the expansion side, a known braking gap automatic adjusting device 14 that regulates the retracted position of the webs 6a, 6a when the diameter is reduced and automatically sets the braking gap is provided. The return spring 12 is provided by winding the coil portion 12a around the strut member 15 of the adjusting device 14.

The braking gap automatic adjusting device 14 is composed of the above-mentioned strut member 15 arranged between the webs 6a, 6a, an adjusting lever 16 and a set spring 17 arranged in the leading brake shoe 4. Adjust lever
16 is pivotally supported by the support pin 18 on the web 6a of the brake shoe 4.

Back plate 3 and brake shoes 5 for trailing
Between, and the input lever 19 for the parking brake,
One end 19a is pivotally supported by the support shaft 20 on the other end of the expansion side of the brake shoe 5, and the wheel cylinder 10 is hydraulically operated by the driver's braking operation, or the input lever 19 is moved to the other end. When you pull through the brake cable 21 connected to 19b, both brake shoes 4,5
Expand one end on the anchor 9 side as a fulcrum and lining 6c, 6c
However, braking action is performed by sliding contact with the inner peripheral surface of a brake drum (not shown) that rotates in the direction of arrow A in FIG.

Also, when this brake operation is released, both brake shoes 4 and 5 are reduced in diameter by the urging force of the return spring 12,
It returns to the original position shown in FIG.

The brake shoes 4 and 5 have the same structure and are symmetrically used, and hooks 12b and 12c for bending the ends of the return spring 12 into a U shape are hooked on the webs 6a. Locking holes 6d are provided at the outer corners of the expansion side end.

In the web 6a of the brake shoe 5 on the trailing side, the pin hole used for attaching the support pin 18 of the adjusting lever 16 in the brake shoe 4 on the leading side is opened in the vicinity of the latch hole 6d. The pin hole is provided as the guide hole 22 in this embodiment. The guide hole 22 is closer to the center of the back plate than the hooking hole 6d of the trailing brake shoe 5, and is deviated from the tensioned position of the return spring 12 to the shoe hold pin 7 side. As described above, the length from the rotation support shaft 1a to the fitting recesses 1g and 1h of the spring engaging portion 1c is set to be substantially the same as the distance between the guide hole 22 and the latch hole 6d.

Next, the mounting of the return spring 12 using the attachment / detachment tool 1 of this embodiment will be described.

The brake shoes 4, 5 are arranged in advance so as to face the back plate 3 shown in FIG. 2, and one hook 12b of the return spring 12 is on the side of the brake shoe 5 that is hooked by the attachment / detachment tool 1, and the other one. The hook 12c is hooked in the hooking hole 6d of the brake shoe 4.

Then, the pivot part 1d of the attachment / detachment tool 1 is fitted into the guide hole 22 so that the rotary support shaft 1a stands upright on the web 6a of the brake shoe 5 on the trailing side, and the return spring 12 is reduced to a free state. When one of the hooks 12b is hooked on the fitting recess 1g on the opposite side of the return spring 12 at the base of the protrusion 1e, the hook 12c is retained by the protrusion 1e in the hooked state (see FIG. 3). And the solid line in FIG. 4).

Next, the rotation support shaft 1a is rotated in the direction of arrow B in FIG. 3 to move the hook 12b to the hook hole 6d while pulling the return spring 12 (see FIG. 2), and if necessary. While tilting the rotation support shaft 1a arbitrarily, the end 12d of the hook 12b is dropped into the hook hole 6d of the brake shoe 5, and both webs 6a, 6
Tension the return spring 12 between a (two-dot chain line in Fig. 4). Then, the rotation support shaft 1a is rotated in the direction of arrow C in FIG. 3 to disengage the pivot portion 1d from the guide hole 22, and the attachment of the return spring 12 is completed.

When removing the return spring 12, the pivot part 1d of the detachable tool 1 is fitted into the guide hole 22, and the spring engaging part 1c is inserted between the hook 12b and the web 6a.
The hook 12b is hooked on the fitting recess 1g, and the rotary support shaft 1a is once rotated in the direction of arrow B in FIG. 3 to return the return spring.
While pulling 12, while tilting the attachment / detachment tool 1 slightly with the pivot part 1d as a fulcrum as necessary, the end 12d of the hook 12b is pulled up from the retaining hole 6d to the upper surface of the web 6a, and the rotation support shaft 1a is moved to the first position. 3 Rotate in the direction of arrow C and remove the return spring 12.

As described above, according to the present embodiment, the attachment / detachment tool 1 having a simple structure can easily and surely perform both attachment and detachment of the return spring 12 which cannot be performed by the conventional detachment tool. In particular, the length from the center of the rotation support shaft 1a of the attachment / detachment tool 1 to the fitting recesses 1g, 1h of the spring engaging portion 1c is set to be substantially the same as the distance between the guide hole 22 and the latch hole 6d. It is possible to engage and disengage the return spring 12 by engaging the hook 12b with the hook hole 6d without fail while expanding and contracting the return spring 12 with a light force.

Further, during the attaching / detaching operation, the hook 12b hooked in the fitting recesses 1g, 1h is prevented from coming off by the projecting piece 1e, so that failure due to careless detachment and loss of the return spring can be surely prevented, and the hook 12b can be reliably prevented. The protruding piece 1e does not hinder even when the is removed from the fitting recesses 1g and 1h.

Further, since the lower surface of the protrusion 1e is provided with the tapered surface 1f, it can be easily inserted between the hook 12b and the web 6a. Further, since the pivot portion 1d is formed into a spherical shape, it is easy to rotate the spring when removing the spring. The tilt of the drive shaft 1a can be smoothly performed.

Furthermore, for the drum brake on the opposite side where the brake constituent members are arranged symmetrically to the above-described embodiment, the other fitting recess 1h and the projecting piece 1e are used for attaching and detaching the return spring, and the attaching / detaching tool 1 is used. The same operation can be performed by rotating in the opposite direction to the above embodiment.

In the above-described embodiment, the guide hole 22 into which the pivot portion 1d of the detachable tool 1 is fitted is a pin hole through which the support pin 18 of the automatic braking gap adjusting device 14 is inserted.
For those without this pin hole, as the guide hole 22,
Half piercings and through holes are formed separately.

The pivot part of the attachment / detachment tool may have a spring engaging part projectingly provided on the tip end side part of the rotary support shaft and provided on the lower surface thereof so as to project in the same direction as the axis of the rotary support shaft.

[Effect of device]

A tool for attaching / detaching a return spring of a vehicle drum brake according to the present invention comprises a spring engaging portion, a protrusion projecting laterally of a rotation support shaft to prevent a hook of the return spring from coming off, and a base end of the protrusion. On both sides, form a pair of fitting recesses to hook the return spring end hooks,
A pivot fulcrum pivot portion fitted into a guide hole formed in the web of the brake shoe is provided at the tip of the rotation fulcrum so as to project from the rotation fulcrum to the pair of fitting recesses. Since the lengths of the return springs are set to be substantially the same as the distance between the hooking holes of the web and the guide holes, both removal and attachment of the return spring can be performed easily and reliably.

In particular, by setting the respective lengths from the rotation support shaft to the pair of fitting recesses to be substantially the same as the distance between the guide hole and the hooking hole, the return spring can be comfortably expanded and contracted with a light force, The hook can be securely aligned with the hooking hole to engage and disengage.

Further, during the attachment / detachment work, the hooks hooked in the fitting recesses prevent the projections from coming off, so failure due to careless disengagement and loss of the return spring can be reliably prevented, and the hooks are disengaged from the fitting recesses. Even when the protrusions do not interfere.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present embodiment. FIG. 1 is a perspective view of a tool for attaching and detaching a return spring, FIG. 2 is a front view of a drum brake, and FIG. A front view of the part and FIG. 4 are sectional views of the same main part. 1 ... Tool for attaching / detaching return spring, 1a ... Rotating spindle, 1b
... bar handle, 1c ... spring engaging part, 1d ... pivot part, 1e ... projecting piece, 1g, 1h ... fitting recess, 2 ... drum brake, 3 ... back plate, 4,5 ... brake shoe, 6a ...
Web, 12 ... Return spring, 12a ... Coil part, 12
b, 12c ... Hook, 12d ... End of hook 12b, 14 ... Automatic braking gap adjusting device, 15 ... Strut member, 16 ... Adjust lever, 18 ... Support pin, 22 ... Guide hole

Claims (1)

[Scope of utility model registration request] 1. A hook at the end portion of a return spring stretched between a pair of brake shoe webs is hooked on a spring engaging portion provided at the tip end side of a rotary support shaft, and the hooks are provided on the web. In a tool for attaching / detaching a return spring of a vehicle drum brake which engages / disengages with a hooking hole of the return spring, the spring engaging portion projects laterally of the rotation support shaft to hook the return spring. And a pair of fitting recesses for hooking the hooks on both sides of the base of the projection, and a guide hole formed in the web at the tip of the rotary support shaft. A pivot fulcrum pivot part to be fitted is provided in a protruding manner, and each length from the pivot fulcrum to the pair of fitting recesses is approximately equal to the distance between the latch hole and the guide hole. Set to the same Vehicular drum return spring for attaching and detaching a tool of a brake, characterized in that the.