JPS5832025Y2 - Brake shoe self-lock prevention structure - Google Patents

Description

[Detailed description of the invention] The present invention is to prevent self-locking of the brake shoes of a DSDA (duo servo double anchor) type drum brake in a mechanical drum brake (or center brake) as shown in Japanese Utility Model Publication No. 42-14065. It's about structure.

In this type of drum brake, when the brake is applied, the expanding end of the pair of arcuate brake shoes becomes the anchor side, which is the so-called secondary shoe, and the drum and brake shoe bite together, resulting in poor shoe return when the brake is released. A self-locking phenomenon may occur.

This phenomenon is extremely inappropriate for the operation of drum brakes, and the inventor of the present invention has conducted various studies in order to solve this problem, and has come to the conclusion that a brake with a structure that does not cause the self-locking phenomenon has been developed. This led to the development of the shoe.

That is, the self-locking phenomenon is noticeable in the so-called secondary shoe where the expanding end is the anchor side due to the relationship between the expanding operation of the arcuate brake shoe and the drum rotation direction, whereas it is hardly observed in the primary shoe. Not yet,
The present inventor believes that this is due to the fact that the direction of rotation of the drum acts to further wedge the expanding side end of the secondary shoe located between the anchor receiver and the drum. Therefore, we have come to believe that the web has a large influence on the stiffness of the part of the brake shoe corresponding to the wedge.

Based on the above, the inventor of the present invention believed that the self-locking phenomenon could be prevented by reducing the rigidity of the part of the anchor side end of the brake shoe corresponding to the web fixing part to some extent, and the self-locking phenomenon can be prevented. As shown in the figure, a concave notch 3 with an open end is formed at the end of the lining 2 of the brake shoe 1 located on the anchor side, and the web 5 of the brake shoe 1 is inserted between the drum (not shown). We have developed a brake shoe 1 that engages the brake shoe indirectly with a certain gap without using a rigid body.

According to experiments, the brake shoe 1 showed extremely good results with respect to the self-locking phenomenon, and there was no occurrence of the brake shoe 1 being bitten, which was clearly determined to be caused by the same phenomenon.

In addition, the brake shoe 1 can use the current rim 4 and web 5 as they are, and only the shape of the lining 2 is changed, so it is better than the conventional one in terms of handling and braking effectiveness. No significant difference was found, and there was a significant difference in the prevention of the above-mentioned self-locking phenomenon.

According to experiments, the desirable notch shape of the lining in the present invention is extremely good when the width of the notch is about 1.5 to 3.5 times the width of the web and the length is about 2 to 3 times the length in the width direction. It has been confirmed that there is.

[Brief explanation of the drawing]

FIG. 1 is a side view of a brake shoe showing an embodiment of the present invention, FIG. 2 is a rear view thereof, and FIG. 3 is a right side view of FIG. 1. 1... Brake shoe, 2... Lining, 3... Notch, 4... Rim, 5
······web.

Claims (1)

[Scope of utility model registration request] In a brake shoe applied to a tenio servo type drum brake, in which a lining is fixed to the outer peripheral surface of an arch-shaped rim, a web is fixed to the inner surface to form a T-shaped cross section, and the expanding side end is the anchor side. , the end of the lining on the anchor side of the brake shoe,
A self-locking prevention structure for brake shoes characterized by a concave shape with a notch corresponding to the fixed part between the rim and the web.