JPS5919726A - Drum brake - Google Patents

Abstract

PURPOSE:To make it possible to adjust automatically the gap between brake shoes by a method wherein a brake shoe holding member and an anchor attached with a compression spring are provided in the title brake. CONSTITUTION:In case where the amount of displacement of each of brake shoes 2 and 3 is larger than the gap between the inner periphery of the drum and the lining surfaces of the brake shoes 2 and 3 when the set value of the gap is the difference between the inner diameter of each of friction rings 9, 9 made of hard rubber and the outer diameter of each of sleeves 10a, 10a the brake shoes 2 and 3 are spread out as both side walls of grooves 2b and 3b slide respectively along the outer peripheries of the friction rings 9, 9. When the brake is released, the brake shoes 2 and 3 return to their original conditions by rotating about bolts 10 so that the ends 2c and 3c of the brake shoes 2 and 3 are separated from the head 8a of an anchor 8, and the anchor 8 urged by a compression spring 11 projects until it comes into contact with the ends 2c and 3c of the brake shoes at a frictioh angle theta, to thereby adjust automatically the gap between the drum and the brake shoes.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drum brake, and more particularly to a drum brake equipped with an automatic adjustment device for a gap between a brake shoe and a drum.

Some hydraulic drum rakes are equipped with an auto-adjuster device, but their structure is complex. In addition, in mechanical drum brakes, the increase in the gap between the brake shoes and the drum due to wear of the lining can be caused by input lever 5.
(See Figure 1) It is common to manually adjust the length of the input cable, rod, etc. in step 1, and for large models, a cylinder equipped with a pressure regulating valve is installed in the middle of the rod. Although there are some, the structure is complex and manufacturing costs are high.

In the present invention, both brake shoes mounted facing a backing plate are sent out in a direction that reduces the gap between the shoes using a holding member fixed to the backing plate as a guide, and both brake shoes are returned by the action of a return means. To provide a drum brake equipped with a device that automatically adjusts the shoe gap by compensating for the expansion of the gap between both ends of the brake shoes on the anchor side by the anchor 11 due to the rotation of the circumference of the holding part when the brake shoe is rotated. Monodeashi,
In particular, it is possible to provide a mechanical drum brake equipped with an auto-adjuster device with a simple structure.

An embodiment of the drum brake according to the present invention will be described based on the drawings.

In Fig. 1, 1 is a backing plate, and on the notching plate 1 there are a pair of brake shoes 2 and 3.
are arranged facing each other.

A cam 4, which is a means for expanding both brake shoes during braking, is in contact with one end 2a, 3a of both brake shoes 2, 3, and a cable 6 is pulled through an inlet camber 5 fixed to the cam 4. By applying an input and tilting the cam 4, both brake shoes 2 and 3 are expanded. Reference numeral 7 is a spring serving as a shoe return means, which returns the nine brake shoes 2.3 to their original positions by removing the input to the inlet cam 5 when the brake is released. 8 is an anchor that supports the other ends of both brake shoes 2.3. Both brake shoes 2 and 3 are provided with grooves 2b and 3b that open to the inside of the web at the bottom of the mounting position of the spring 7 on the inside of the web. As shown in detail in FIG. 2, seven traction devices are provided in the grooves 2b and 3b. The friction device is constructed by inserting seven friction rings 9, 9 made of hard rubber, for example, and when the friction rings 9, 9 move within the grooves 2b, 3b, friction is generated between them and the side walls of the grooves 2b, 3b. Has resistance. A sleeve 10a serving as a holding member is fitted onto the friction ring 9, and the gap 8a between the sleeve 10 and the other end 2C of both brake shoes 2.3.

3c with a friction angle θ, and is formed in a conical or wedge shape by contracting toward the tip. The base 8b of the anchor is the Tsukifugu plate 1.
The hole 8 drilled in the base 8b is inserted into the hole 1a of the hole 1a.
A compression coil spring 11 is attached to the backing plate 1 in b'.
The anchor 8 is compressed between the other ends 2c of both brake shoes.

3c with a friction angle θ.

Next, the operation of the drum brake according to the present invention will be explained.

During braking, input is made to the input lever 5 to tilt the cam 4, which is an expanding means that contacts one end 26.3a of the brake shoe, and the brake shoe 2.3 is expanded and rotates around the anchor 8 as a fulcrum (not shown). It is pressed against the inner circumference and generates braking force. And when the III is in operation, both brake shoes 2.3
The difference between the inner diameter of the friction rings 9, 9 and the outer diameter of the sleeves 10a, 10a is the set value. In the case where the brake shoes 2.degree. 3 are widened, both side walls of the grooves 2b, 3b slide on the outer periphery of the friction ring 9.9. And input reno-5
When the input buff is released, the brake shoes 2 and 3 are returned by the action of the spring 7. At this time, both plays =
li-shoe z, 3i1:sunruto 10. Since it rotates using the 10 as a fulcrum, the brake shoe and other parts 9ii: ”C
130 also separates the head 8a of the anchor, so the anchor 8, which is biased by the compression coil spring 11, protrudes until it contacts the other ends 2c and 3c of both brake shoes at a friction angle θ, and the gap between the drum and the brake shoes is removed. Auto adjustment is made.

FIG. 4 shows another shape of the anchor. The other ends of both brake shoes 2c, 3c [Abutting anchor 8
Both sides of the head 8'a of the brake shoe 8'a are formed in a step-like manner, and the width thereof is reduced in a stepwise manner toward the tip. Depending on the sliding movement of the rings 9, 9 with respect to the outer periphery, an auto-adjustment action is performed in stages when the brake shoes 2, 3 are returned.

The drum brake according to the present invention is provided with an expanding means between one end of the drum brake, which is mounted facing each other on the Tsukifugu plates, the other end of which is brought into contact with an anchor, and a shoe between both brake shoes. In a drum brake equipped with a return means, a groove is provided on the inner side of the web of both brake shoes, a friction device is inserted into the groove, and the friction device is inserted into the friction device with a gap and one end is fixed to the backing plate. The anchor has an auto-adjust device whose base part is guided by the backing plate and whose head part [1] of the anchor, which has a compression spring interposed between it and the backing plate, is contracted toward the tip. Therefore, the construction is simple, and the automatic adjustment of the gap between the drum and the brake shoe is easily achieved by the frictional action of the friction device and the protrusion/opening of the anchor, making the structure simple. We were able to provide a complete mechanical drum brake for the 45.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a mechanical drum brake according to the present invention, FIG. 2 is a sectional view taken along the line ■-■ in FIG. 1, FIG. 3 is a sectional view taken along the line m-m in FIG. 1, and FIG. is a sectional view corresponding to FIG. 3 showing another anchor shape; 1: Backing plate, 2-hole hole, 2-brake shoe, 2b: groove, 3-brake shoe, 3b: groove, 4: cam (expansion means), 7: spring (shoe return means), 8: Anchor, 8a: Head, 8b: Base, 8'
: Anchor, 8'a: Head, 9:7 Reaction ring (
Friction device), 10: Bolt (holding member), 10
anisleeve, 11: Compression coil spring agent Toshiyuki Maeda Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. In a drum brake in which an expanding means is provided between one end of the brake shoes mounted oppositely on a backing plate, the other end is brought into contact with an anchor, and a shoe return means is provided between both brake shoes. , a groove opening inside the webs of both brake shoes is provided, a 7-reaction device W is inserted into the groove, a holding member is inserted into the friction device with a gap, and one end is fixed to the notching plate; A drum brake characterized in that the drum brake has an auto-adjuster device whose base portion is guided by a pulling plate and whose width is reduced toward the tip of an anchor wall with a compression spring interposed between the backing plate and the backing plate.