JPS5931944Y2 - Automatic braking gap adjustment device for drum brakes - Google Patents

Description

[Detailed description of the invention] The present invention has a sliding block bent in a substantially U-shape, which is provided on the back plate so as to be slidable in the direction in which the brake shoes expand. A support shaft having a tapered surface inclined in the exit direction is rotatably provided on the sliding block, a brake lever is arranged between the side walls of the opening of the sliding block, an adjustment lever is loosely inserted into this support shaft, and one end thereof is placed between the side walls of the opening of the sliding block. is brought into contact with one end surface of the brake lever, the claw at the other end is engaged with an adjustment gear that extends the adjustment bolt, and a compression spring is provided between the head of the support shaft and the adjustment lever, and this compression spring is set. This relates to an automatic braking gap adjustment device for a slider-pull type internally expanding drum brake in which the adjustment lever is pressed in one direction toward the brake lever by a load, and the adjustment lever is brought into contact with the tapered surface of the support shaft. It is characterized in that a spring member is hooked between the two levers so as to be in constant pressure contact with the levers.

The purpose of this invention is to keep the adjustment lever in constant pressure contact with the brake lever so that the rotational force of the brake lever during braking is transmitted to the adjustment lever without any loss of stroke, thereby improving the stability and reliability of the adjustment operation. The present invention provides an automatic braking gap adjustment device for the drum brake.

An embodiment of the present invention will be described below with reference to the drawings.

Reference numeral 1 denotes a back plate fixed to a stationary portion of the vehicle body, and a pair of left and right brake shoes 2, 2 are arranged inside the back plate.

A sliding block 3 is bent into a substantially U-shape and is disposed between the ends of both brake shoes 2, 2.
A rattling prevention spring 6 is interposed between the fixed plate 4 and the slide plate 5 which are engaged with each other, and the slide plate 5 and the set plate 7 sandwich the back plate 1 and are tightened and fixed with the tightening bolts 8. The brake shoes 2.2 are provided so as to be slidable in the direction of expansion of the brake shoes 2.2.

9 is an adjustment bolt screwed onto the sliding block 3;
The head 9a fits and contacts the shoe web 2a on the trailing side, and expands as the adjustment gear 10 rotates.

11 is a brake lever arranged with a gap between the opening side walls 3 a and 3 a of the sliding block 3;
A support shaft 12 is provided extending inward from the back plate 1 by press-fitting and fixing the serrations, and this support shaft 12
are rotatably engaged with notches 3b, 3b formed in the opening side walls 3a, 3a of the sliding block 3, and the operating side end surface 11a of the brake lever 11 is in contact with the leading side shoe web 2a. ing.

Reference numeral 13 denotes an adjustment lever for rotating the adjustment gear 10, which is loosely inserted into the support shaft 12, and is attached to one end of the upper part 13.
a is in contact with the operating side end surface 11a of the brake lever 11, and the other end claw portion 13b is engaged with the adjustment gear 10.

Reference numeral 14 denotes a compression spring attached to the support shaft 12, which biases the adjustment lever 13 in the direction of the brake lever 11 with the set load of the spring, thereby tilting the large diameter hole of the adjustment lever 13 in the direction in which the support shaft 12 extends. Tapered surface 1
2 It is in pressure contact with a.

3c, 3c are stopper parts formed by bending inward the upper portions of the opening side walls 3a, 3a of the sliding block 3, and the non-operating side end surface 11b of the brake lever 11 is the stopper part 3c, 3c. , and sets the backward limit of the brake lever 11 in the non-actuating direction.

Thereby, it is possible to suppress variations in the tip of the claw when the claw portion 13b of the adjustment lever 13 and the adjustment gear 10 are engaged with each other.

And, the non-operating side end surface 11 of this brake lever 11
The distance 11 between the abutment point between the stopper portions 3c and 3c of the sliding block 3 and the center point of the support shaft 12 is increased, and the distance 11 between the claw portion 13b of the adjustment lever 13 and the center point of the support shaft 12 is increased. When you approach the distance 12, the adjustment lever 1
Variations in the engaged state of the claw portions 13b of No. 3 can be minimized as much as possible.

Reference numeral 15 denotes a spring member, which passes through the intermediate portion 15a into the holding hole 13C of the adjustment lever 13, and has one end portion 15b.
is engaged from below the top surface 13d of the adjustment lever 13 in a locking groove 11C formed at the top of the non-actuated end surface 11b of the brake lever 11, and the other end 15C is adjusted from above the top surface 13C. The lever 13 is locked in a locking groove 13e formed on the outer side of the back plate, and the hook is passed between both levers 11.13, and the adjustment lever 13 is constantly pressed against the operating side end surface 11a of the brake lever 11. are doing.

As a result, the rotational force of the brake lever 11 is transmitted to the adjustment lever 13 without any loss of stroke, and the adjustment operation can always be performed stably and reliably.
Since the hook passes through the holding hole 13C of No. 3 and extends between both levers 11 and 13, the adjustment lever 13 is securely pressed against the brake lever 11 without falling off even after long-term use.

16 is a dust boot whose end is locked to the back plate 1, 17 is a return spring provided between the brake shoes 2 near the sliding block 3, and 18 is an anchor 19.
This is an anchor spring installed between the nearby brake shoes 2 and 2.

Next, the operation of this embodiment will be explained.

When the wire (not shown) connected to the brake lever 11 is pulled and the brake lever 11 is rotated in the direction of the arrow in FIG. 2, the brake shoe 2 on the toeing side expands and the lining 2b is attached to the inner surface of the brake drum. The sliding block 3 slides on the back plate 1 due to the reaction force, and the trailing side brake shoe 2 is expanded.
Braking is performed by pressing the lining 2b against the inner surface of the brake drum on the opposite side.

By repeating this braking, the linings 2b and 3
When b wears a predetermined amount, the amount of rotation of the brake lever 11 increases, and this amount of rotation is reliably transmitted by the spring member 15 to the adjustment lever 13, which is always in pressure contact with the brake lever 11, without any loss of stroke. The play between the claw portion 13b and the teeth of the adjustment gear 10 is eliminated, and the adjustment gear 10 is rotated.

As a result, the adjustment bolt 9 expands to compensate for the amount of wear on the linings 2b, 2b, and the braking gap is automatically maintained at a constant value.

Then, the claw portion 13b of the adjustment lever 13 passes over one tooth of the adjustment gear 10 and engages with the next tooth, and the adjustment lever 13 returns to its normal position, but at this time, the non-operating side end surface 11b of the brake lever 11 Sliding block 3
It is possible to reliably return to the normal position by abutting against the stopper portions 3c, 3c.

As described above, according to the present invention, a spring member is hooked between the adjustment lever and the brake lever, and the adjustment lever is always pressed against the brake lever, so that when the brake lever is rotated during braking, the rotation is prevented. Since the power can be transmitted to the adjustment lever without any loss of stroke and rotate the adjustment gear, the adjustment operation is reliable and stable, and the braking gap can be adjusted well. Since the lever is held through the brake lever and the hook is passed between both levers, the adjustment lever can be securely pressed against the brake lever, and the spring member can be used successfully for a long period of time without falling off. have.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a front view, and FIG. 2 is a sectional view taken along line I--■ in FIG. 1. 2.2 is a brake knee, 3 is a sliding block, 9 is an adjustment bolt, 10 is an adjustment gear, 11 is a brake lever, 12 is a support shaft, 13 is an adjustment lever 14 is a compression spring, and 15 is a spring member.

Claims (1)

[Scope of utility model registration request] 1. A sliding block bent in a substantially U-shape is provided on the back plate so as to be slidable in the direction of expansion of the brake shoes, and the support has a tapered surface that extends to one side fixed to the brake lever and slopes in the direction of extension. A shaft is rotatably provided on the front sliding block, a brake lever is arranged between the side walls of the opening of the sliding block, an adjustment lever is loosely inserted into the support shaft, and one end thereof is attached to one end surface of the brake lever. and the other end of the claw is engaged with an adjustment gear that extends the adjustment bolt, and a compression spring is provided between the head of the support shaft and the adjustment lever, and a set load of the compression spring causes the adjustment lever to be moved. In the automatic braking gap adjustment device for a slider-pull type internally expanding drum brake, the adjustment lever is pressed against the tapered surface of the support shaft by urging the brake lever in one direction, and the adjustment lever is always pressed against the brake lever. An automatic braking gap adjustment device for a drum brake, characterized in that a spring member is hooked between the two levers. 2. The scope of the utility model registration claim, characterized in that the middle portion of the spring member is held through a holding hole formed in the adjustment lever, and one end is locked to the adjustment lever and the other end is locked to the brake lever. The automatic braking gap adjustment device for a drum brake according to item 1.