JPS6342189Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a brake shoe support mechanism in a drum brake device.

During braking, a drum brake device brings pads, which act as wear materials on the outer surface of the rim, into contact with the inner peripheral surface of the drum with strong mutual pressure, and the rotation of the wheel is braked by the frictional force generated on the contact surface. It is composed of Therefore, the brake shoe has an arcuately curved rim part with almost the same curvature as the drum's circumferential surface, and an arcuately curved web that reinforces this rim part. are integrally provided to form a T-shape. There are various mechanisms for pressing this shoe toward the inner circumferential surface of the drum, but the drum brake with the support mechanism according to this invention is
In particular, the present invention relates to a drum brake device having a mechanism for mechanically or hydraulically pressing both ends of the shoe. In this type of both-end pressing type brake shoe, the pressing portions at both ends only engage with the pressing mechanism to press the shoe against the inner peripheral surface of the drum. A shoe guide and support mechanism is provided in the intermediate web.

As shown in FIG. 1, in the conventional shoe guide support mechanism 1, a stud 2 fixed upright on a drum base plate 1 is inserted into a through-hole groove 4 provided in a web 3, and the head A nut 7 is attached to the protruding head of the stud 2 through a washer 5.
It is known that the washer 5 and the web 3 are connected by screws, and the opposing surfaces of the washer 5 and the web 3 are formed as a guide support surface. In addition, the nut 7 and washer 5 may be damaged due to vibration of the shoe during brake operation or uneven wear of the pads.
Nut 7 to eliminate collision scratches that occur on the contact edge of
There is one in which the washer 5 is integrally formed into a flanged nut, and the outer edge of the contact between the flanged part and the web 3 is chamfered particularly in an arc shape.

However, in any of the mechanisms, in a brake device that operates repeatedly and is frequently used, the contact edge between the nut 7 and the washer 5 and the guide surface of the washer 5 in the former example, and the guide surface of the washer 5 in the latter example. Another disadvantage is that galling occurs on the guided surface of the web 3, making it difficult for the brake shoe to move smoothly.

The object of this invention is to provide a guide and support mechanism for the brake shoe which is formed so as to eliminate galling which occurs on the contact surface between the washer 5 and the web 3 and to facilitate smooth movement of the brake shoe.

Examples will be described with reference to the drawings.

FIG. 2 is a partially cutaway plan view of the drum brake. In the figure, 10 is a drum board, 11 is a brake shoe, 12 is a pad, 13 is a rim part, 14
is the web, 15 and 16 are the wheel cylinders, 1
7 and 18 are return springs, 19 is shoe 1
This is the No. 1 guide support mechanism. When the brake is applied,
The brake shoe 11 is a wheel cylinder 15,
Both ends of the web 14 are pressed by the pads 16 to bring the pads 12 into contact with the inner peripheral surface of the drum to perform braking, and when the brake is released, the return springs 17 and 18
It is pulled back and restored to its original position. The guide support mechanism 19 guides the movement of the brake shoe 11 during this time. As shown in FIG. 3, this guide support mechanism 19 vertically fixes a stud 20 on the drum substrate 10.
0, and at the same time, the outer surface of the rim part 13 is inserted into the through-hole groove 21 of the web 14 of the brake shoe 11 placed parallel to the inner peripheral surface of the drum. A nut 7 is screwed onto the protruding end edge via a cover washer 25, and fixed with a cotter pin 24 so as not to loosen. In this state, the axis of the stud 20 and the rim portion 13 are parallel, and the web 14 provided perpendicularly to the rim portion 13 is perpendicular to the axis of the stud 20. Further, the covering washer 25 loosely fitted into the stud 20 and the nut 7 screwed onto the stud 20 are formed so as to be in contact with each other without a gap. That is, the web 14 is in contact with one surface of the covering plate 22 on the covering washer 25, and the bearing surface of the nut 7 is in contact with the covering washer 22.
5 is screwed so as to be in contact with the other surface of the covering plate 22. Further, the through-hole groove 21 of the web 14 is formed into an elongated hole corresponding to the sliding distance of the brake shoe 11. Stud 20 of covered washer 25
The fitting hole is formed to have a slight loose fitting allowance. Further, the outer diameter of the washer 5 of the covering washer 25 is formed to be larger than the short diameter of the through hole groove 21. That is, the covered washer 25 is formed by covering the washer 5 with a material harder than the nut 7 and the web 14 of the brake shoe 11, such as a thin plate of tool mesh, as shown in FIG. In this case, the cover washer 25 is made of a thin plate material with a through hole of the same diameter as the loose fit hole 26 of the washer 5, and the cover plate 22 is placed outside the cover plate 22 with the loose fit hole 26 and the through hole overlapped. The periphery is smoothly bent and coated, and the coated edge is extended to a range smaller than the length of the opposite edge of the nut 7,
At the same time, the covering edge is fixed and formed integrally with the nut 7. In other words, the cover washer 25 is formed with a hardness difference on the contact surface, and at the same time is formed so that it can move independently of the nut 7.

According to this invention, the washer does not come into direct contact with the web of the brake shoe, but instead comes into contact with a coated washer coated with a thin plate of high hardness, making it possible to completely eliminate the so-called galling phenomenon due to the difference in hardness. Further, since the covered washer can move freely, the covered washer itself rotates and the contact position with the nut and web changes, so that no local galling occurs at all. Furthermore, since the covered washer is not a spring seat plate, even if the nut, the covered washer, and the web momentarily come into contact with each other with a large mutual pressing force during braking, the web is reliably fixed at the contact position and guided. This has the practical benefit of not inducing unnecessary vibration of the user and preventing uneven wear of the lining. Furthermore, since the outer circumferential edge of the covering material of the covering washer is smoothly bent, this portion will not locally bite into the web. In addition, the coated washer has coating material on the contact surface with the nut, so
There is no possibility that the so-called galling phenomenon will occur due to biting between the nut side edge and the covering washer. Since galling does not occur, it is possible to provide a practical brake shoe support mechanism that is effective in preventing return failure.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional explanatory view of the shoe guide and support mechanism in the conventional example, FIG. 2 is a plan view with a part of the drum breuil removed, FIG. 3 is a cross-sectional explanatory view of the shoe guide and support mechanism according to this invention, and FIG. The figure is an explanatory cross-sectional view of the covered washer. Explanation of symbols, 1, 10...Drum board, 2, 2
0...Stat, 3,14...Web, 4,21
...Through hole groove, 5...Washer, 7...Nut, 11...Brake shoe, 12...Pad,
13... Rim part, 15, 16... Wheel cylinder, 17, 18... Return spring, 19
...Guide support mechanism, 22 ... Cover plate, 24 ... Cotter pin, 25 ... Cover washer, 26 ... Loose fitting hole, 2
7...Small diameter plate.

Claims (1)

[Scope of utility model registration request] Insert the stud that is fixed upright on the drum board into the through-hole groove provided in the web of the brake shoe, fit the washer loosely into the protruding end, and screw the nut.
A brake shoe support mechanism that slidably supports a brake shoe on a drum base plate includes a ring-shaped washer 5 having an inner diameter that loosely fits into the stud 20 and an outer diameter slightly larger than the diagonal length of the nut 7; A thin plate made of a material harder than the nut 7 and the web 14, with a through hole having the same diameter as the inner diameter of the nut 7 and the web 14.
A cover washer 25 is formed by overlapping the inner diameter of the washer 5 and the through hole, and the outer peripheral edge of the thin plate is smoothly bent to cover the nut 7, and the nut 7 is screwed onto the web 14 and the stud 20. Covered washer 2
A brake shoe support mechanism characterized by providing a brake shoe support mechanism.