JPS6340667Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention has a pair of brake shoes slidably supported on a back plate, one end of which is brought into contact with an anchor, and the other end is provided with a brake shoe expanding means. , both ends of the strut are brought into contact with the shoe web near the brake shoe expanding means, the feed pawl of the adjustment lever rotatably provided on the shoe web is engaged with the adjustment gear of the strut, and the strut is rotated by rotating the adjustment gear. This invention relates to an automatic braking gap adjustment device for vehicle drum brakes that automatically adjusts the braking gap by extending the braking gap.

[Prior art]

Conventionally, in this type of automatic braking gap adjustment device, when the lining reaches the limit of wear and the brake shoe is replaced, or when the brake system is repaired, the drum is removed and the adjustment lever is raised with a tool or the like to connect it to the adjustment gear. After releasing the mesh, the brake shoe is replaced and various parts of the brake system are repaired. In addition, if the lining of the brake shoe is biting into the braking surface of the drum and the drum cannot be removed, insert a tool through the window provided in the back plate and remove the adjustment lever that is meshed with the adjustment gear from the adjustment gear. The gear is pushed away to release the engaged state, and the adjustment gear is rotated in the opposite direction to retract the strut, thereby removing the drum and replacing the brake shoe or repairing the brake device.

To release the engagement between the adjustment lever and the adjustment gear, push a tool such as a screwdriver through the window drilled in the back plate and push up the adjustment lever to release the engagement between the feed pawl and the adjustment gear. I used another tool to reverse the adjustment gear, but because the tip of the adjustment lever is flat, tools such as screwdrivers slip easily, and the tool often comes off the adjustment lever while reversing the adjustment gear. There were disadvantages such as the adjustment gear sometimes meshing with the other, and it took time to reverse the adjustment gear because tools such as two screwdrivers had to be inserted through the small window.

[Purpose of invention]

The present invention has been made in view of the above points, and an object of the present invention is to provide an automatic braking gap adjustment device for a drum brake for a vehicle, which is equipped with an adjustment lever that allows the adjustment gear to be easily reversed using only one tool such as a screwdriver. With the goal.

[Structure of the idea]

In order to achieve the above purpose, in this invention,
At the position opposite to the feed pawl at the tip of the adjustment lever, that is, at the position on the return spring side, it is inclined in the direction opposite to the back plate, and its tip extends from the return spring to the side opposite to the back plate, so that the adjustment gear is A guide part is formed to ride on the return spring that separates the feed pawl from the adjustment gear during rotation, and by forcibly reversing the adjustment gear, the adjustment lever that engages the feed pawl with the adjustment gear is pushed in the direction of the return spring. The adjustment lever is moved to rest on the straight portion thereof, and the tip of the adjustment lever is floated to release the engagement between the feed claw portion and the adjustment gear.

〔Example〕

Next, one embodiment of the present invention will be described based on the drawings.

1 is a back plate fixed to the vehicle body;
In the figure, a wheel cylinder 2 is fixed at an upper position, and an anchor 3 is fixed at a lower position.
4, 4 are a pair of brake shoes arranged in the back plate 1, and shoe webs 4a, 4a,
Shurim 4b, 4b and lining 4c, 4
It consists of c. One end of the shoe webs 4a, 4a of the pair of brake shoes 4, 4 is in contact with a pair of pistons 5 of the wheel cylinder 2, and the other end is in contact with the operating end of the anchor 3, and the operation of the pair of pistons 5 causes Both brake shoes 4, 4 are expanded so that the linings 4c, 4c come into sliding contact with the inner peripheral surface (not shown) of the brake drum.

6 is the shoe web 4 with one end on the trailing side.
7 is a second strut whose one end is in contact with the leading-side shoe web 4a; 8 is an adjustment bolt having an adjustment gear 9 in the middle; the threaded side thereof is screwed into the first strut 6; The other end is rotatably fitted into the second strut 7.

Reference numeral 10 denotes an adjustment lever rotatably provided on the leading side shovel web 4a, a feed claw portion 10b formed at the tip of the arm portion 10a meshes with the adjustment gear 9, and a tongue piece 10d formed on the base portion 10c engages with the adjustment gear 9. The adjusting lever spring 11 abuts on the notch 7a of the strut 7, and has one end locked on the leading side shoe web 4a.The other end of the adjust lever spring 11 is locked on the arm portion 10a. As a result, the adjustment lever 10 rotates clockwise in FIG. 1 when the brake shoes 4, 4 are expanded, and as the linings 4c, 4c wear out, the feed pawl portion 10b rotates the adjustment gear 9, thereby adjusting the adjustment lever 10. The bolt 8 is screwed out from the first strut 6, and the first strut 6 and the second strut 7 are extended to adjust the braking gap between the linings 4c, 4c and a drum (not shown). Reference numeral 10e designates a riding guide portion formed at the tip of the arm portion 10a of the adjustment lever 10 at a position opposite to the feed pawl portion 10b, that is, at a position on the return spring side, and inclined in the direction opposite to the back plate. is extended to a position overlapping the straight portion 12a of the shoe return spring 12, which is fixed at both ends to the brake shoes 4, 4 and stretched. 13
is a window formed in the vicinity of the adjustment gear 9 of the back plate 1, and is normally closed by a grommet 14.

Next, the operation of this embodiment will be explained.

When replacing the brake shoe after the lining has reached its wear limit due to repeated braking, or when repairing the brake system, first remove the brake drum and use a tool to rotate the adjustment gear 9 in the reverse direction. The feed claw portion 10b of the adjustment lever 10 is pushed toward the straight portion 12a of the return spring 12, and the inclined ride-up guide portion 10e of the adjustment lever 10 comes into contact with the straight portion 12a. 10 floats up, the feed pawl portion 10b climbs over the tooth tip of the adjustment gear 9, and the adjustment gear 9 rotates by one tooth. bite into adjacent teeth.

By repeating the above operations, the adjustment gear 9 is rotated in the opposite direction, the length of the struts 6 and 7 is contracted, and the brake shoes 4 and 4 are removed.
Replace with a new brake shoe and repair each part.

If the linings 4c, 4c bite into the braking surface on the inner circumference of the drum and the drum cannot be removed, remove the grommet 14 and use a tool inserted through the window 13 of the back plate 1 to reversely rotate the adjustment gear 9 in the same manner as described above. , the struts 6 and 7 are retracted, the drum is removed, and the brake shoes 4 and 4 are replaced and various parts are repaired.

In the above embodiment, the ride-up guide part at the tip of the adjuster lever was positioned so as to face the straight part of the return spring, but the same effect can be obtained even if it is positioned so as to face the coil part of the return spring. be able to.

[Effects of the invention] As described above, the present invention has the tip of the adjustment lever inclined toward the opposite side of the backplate, and the tip of which extends from the return spring toward the opposite side of the backplate. Since we have formed a guide part that rides on the return spring that separates the feed claw part from the adjustment gear, the meshing between the adjustment gear and the adjustment lever can be automatically released by simply forcibly rotating the adjustment gear in the reverse direction with a single tool. , it enables continuous reverse rotation, making it easy to perform reverse rotation work on the adjustment gear.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, in which Fig. 1 is a front view, Fig. 2 is a cross-sectional side view taken from Fig. 1,
FIG. 3 is a perspective view of the adjustment lever. 1 is the back plate, 4 is the brake shoe, 4
a is the shoe web, 4b is the shoe rim, 4c is the lining, 6 and 7 are the struts, 8 is the adjustment bolt, 9 is the adjustment gear, 10 is the adjustment lever, 10a is the arm part, 10b is the feed pawl part, 10e is the riding guide 12 is a shoe return spring, 12a is a straight portion, 13 is a window portion, and 14 is a grommet.

Claims (1)

[Scope of utility model registration request] One end of a pair of brake shoes slidably supported on a back plate is brought into contact with an anchor, the other end is provided with a brake shoe expansion means, a return spring is stretched between the brake shoes, and a return spring is placed in the vicinity of the return spring. Both ends of the strut are brought into contact with the shoe web of the strut, and the feed pawl of the adjustment lever rotatably provided on the shoe web is engaged with the adjustment gear of the strut.By rotating the adjustment gear, the strut is extended and the braking gap is automatically adjusted. In the drum brake to be adjusted, at a position on the return spring side opposite to the feed pawl portion of the tip of the adjustment lever, the adjustment lever is inclined in a direction opposite to the backplate, and the tip thereof extends toward the side opposite to the backplate from the return spring. An automatic braking gap adjustment device for a drum brake for a vehicle, characterized in that a guide portion that rides on a return spring is formed to separate the feed pawl portion from the adjustment gear when the adjustment gear rotates in reverse.