JPS6139130Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a support structure for a shoe return spring in a drum brake.

Conventionally, in drum brakes, when the shoe return spring cannot be directly stretched between opposing shoes due to the small space, and the shoe return spring is miniaturized, It is known that a toggle pin 100 is used as shown in FIGS. 1 and 2, and the elastic tensile force of the spring is expanded to the lever ratio L/l.

In this type of drum brake, the shoe return springs 101, 101 are
The toggle pin 10 is inserted through the web of 5,106 and is swingably planted on the backing plate 107.
0,100 and pin 104,1 fixed to anchor bracket 102 or wheel cylinder 103
04, both shoes 10
As the linings 5 and 106 wear, a difference occurs in the tension of both shoe return springs 101, 101. Especially when the wheel cylinder of a tooling flake is opened on one side, as both linings wear, the toe of the shoe becomes different. The stretch of the shoe return spring hung on the side is greater than the stretch on the heel side, resulting in severe usage conditions in terms of stress.

Therefore, the present invention has two show return
The springs are connected by a rotatable link to balance the stresses in both show return springs.

Next, an embodiment in which the present invention is applied to a two-leading brake with one wheel cylinder opening will be described. In FIG. 3, numerals 1 and 2 are brake shoes arranged opposite to the bucking plate 3, and between the toe side 1a of the brake shoe 1 and the heel side 2a of the brake shoe 2. A single-opening wheel cylinder 4 is sandwiched between the two. Reference numeral 5 designates a link for connecting the shoe return spring, which is rotatably pivoted to a pin 6 fixed to the bucking plate 3 or the wheel cylinder 4, and has a through hole provided at one end of the link 5. 7 and show 1
There is a show return spring 9 between the through hole 1b provided in the web of the link 5, and the through hole 2b provided in the web of the show 2 and the through hole 8 provided at the other end of the link 5.
A show return spring 10 is stretched between the two.

FIG. 4 is a plan view of the link 5, which forms a "rectangular" shape centered on the insertion hole 5a of the pin 6, and has a transparent hole that is the point of action of the show return springs 9, 10 with the pin 6 as a fulcrum. Distance A to 7, 8,
The ratio A/B of B constitutes the lever ratio. The angle α of the link 5 is determined in consideration of the direction of movement of the show return springs 9 and 10. In a two-leading brake with a single-opening wheel cylinder, the show return springs 9 and 10, which are in the solid line position when the lining is new, have been moved to the position shown by the imaginary line due to wear, with a smaller size on the heel 2a side and a smaller size on the toe 1a side. Therefore, the lever ratio A/B is selected to be greater than 1. As the lining wears out, the link 5 rotates accordingly. Therefore, the show return on the toe 1a side
A part of the amount of expansion of the spring 9 is borne by the shoe return spring 10 on the heel 2a side, resulting in a reduction in stress on the shoe return spring 9 on the toe 1a side.

As can be understood from the above explanation, according to the present invention, the stress of the shoe return spring, which is generally tensioned on the shoe side that has a large amount of movement, is reduced by the rotation of the connecting link to the shoe return spring on the other side.・
By balancing the stress with the spring, the generated stress can be reduced, making it possible to downsize the show return spring, and also making it possible to eliminate the conventional toggle pin.

[Brief explanation of drawings]

FIG. 1 is a partial plan view of a drum brake equipped with a toggle pin, FIG. 2 is an end view taken along line A-A in FIG. 1 showing the toggle pin, and FIG. In the plan view, Figure 4 shows
FIG. 2 is a partial plan view showing a support structure for a shoe return spring according to the present invention. 1, 2... Brake shoe, 3... Bucking plate, 4... Wheel cylinder, 5... Link, 6... Pin, 9, 10... Shoe return spring.

Claims (1)

[Scope of utility model registration request] Between both ends of a link having a lever ratio, which is rotatably pivoted to a bucking plate of a drum brake or a pin installed in a wheel cylinder, and a shoe disposed opposite to the bucking plate. A support structure for the show return spring of a drum brake, characterized by having a show return spring stretched over the drum brake.