JPH0122500B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a gap adjusting and stopping device between a brake drum and a lining in a drum brake.

<Prior art> An example of a conventionally known device of this type is shown in FIGS. 1 and 2.
To explain with the diagram, 1 is a back plate, 2,
A pair of opposing brake shoes 3 are movably mounted on the back plate 1.

The brake shoes 2 and 3 are the shoe rims 2a and 3, respectively.
3a and shew webs 2b, 3b are usually welded to form a T-shaped cross section, and linings 2c, 3c are provided around the outer periphery of the shew webs 2a, 3a.

A cylinder 4 fixed to the back plate 1 and a fixed anchor 5 are installed between the upper and lower adjacent ends of each of the brake shoes 2 and 3.

A brake lever 7 is pivotally supported by a pin 6 near the upper end of the brake shoe 3, and one end of a strut 8 is engaged with the intermediate portion of the lever 7.

A toothed element 9 having small teeth 9a carved on its outer periphery is fixed to the intermediate portion of the strut 8 so as not to rotate.

A bell crank lever 10 is rotatably supported at the other end of the strut 8 by a pin 11 so as to be slidable in the longitudinal direction of the strut 8, and its first arm 10a is connected to an outer cam surface 10b and an inner cam surface 10b. Surface 10c
It is loosely fitted into the opening 2d of the shew web 2b with a predetermined gap δ, and the outer cam surface 10b is normally in contact with the inner end of the opening 2d by the shew return springs 12a and 12b.

The second arm 10d of the bell crank lever 10 has teeth 1 that mesh with the toothed element 9 on the arcuate outer end surface.
0e is engraved, and a spring 13 is normally tensioned so that the teeth 9a and 10e of both teeth mesh with each other.

Reference numeral 14 denotes a spring stretched between the brake shoe 3 and the toothed element 9 or the strut 8, and its load is set to be larger than that of the spring 13.

When the cylinder 4 operates in the above-described configuration, the brake shoes 2 and 3 expand against the return springs 12a and 12b and come into sliding contact with a rotating brake drum (not shown).

At this time, the spring 14 causes the brake lever 7 and strut 8 to follow the movement of the brake shoe 3 almost integrally.

Now, the amount of expansion of the shoes 2 and 3 exceeds a predetermined amount, that is, the gap δ between the first arm 10a of the bell crank lever 10 and the opening 2d of the shoe 2 and the tooth 9 of the toothed element 9
If the amount exceeds the sum of the height of a and the height of tooth 9a and 10e
The mesh is released.

Therefore, in FIG.
is rotated clockwise to a new position such that it meshes with the toothed element 9, thereby increasing the effective length of the strut 8, thereby keeping the gap between the brake drum (not shown) and the linings 2c, 3c always constant. It is something that can be maintained.

<Problems with conventional technology> The conventional drum brake adjustment technology has the following problems.

<A> If the bell crank lever 10 continues to undergo unlimited angular displacement, the metal surface of the brake rim 2a or 3a will eventually come into sliding contact with the brake drum (not shown), damaging the drum or causing a reduction in braking force. There were some shortcomings.

<B> As a means of eliminating the drawback of <A> above, conventional adjustment stops have been provided in which the tip of the first arm 10a of the bell crank lever 10, which is projected from the opening 2d of the shew web 2b, is formed into a piece shape to form a hook-shaped portion 10f. A device is provided so that, as shown in FIG. 3, when the end edge of the hook-shaped portion 10f comes into contact with the shew web 2b, further rotation is prevented.

Therefore, the driver can sense the subsequent increase in pedal stroke and can prevent the above-mentioned drawbacks from occurring.

However, especially in the case of the above-mentioned leading-trailing drum brake, the ratio of the amount of lining wear at the maximum surface pressure position is generally the same due to differences in the shoe factor and the maximum surface pressure position of the pair of brake shoes 2 and 3. 1:1-3:
The shape of the hook-shaped portion 10f of the bell crank lever 10 is determined so that the shaft rim does not come into sliding contact with the drum even if it is worn at a ratio of 3:1.

Therefore, if wear occurs at a ratio close to 1:1, the adjustment stop device will operate even though there is sufficient remaining lining on both sides.
I had to replace it with a new brake shoe, which was a lot of waste.

<Object of the present invention> The present invention has been made in view of the above-mentioned drawbacks.
The purpose of the present invention is to provide a drum brake adjustment/stop device that can effectively utilize resources.

<Configuration of the Present Invention><A> First Example The first example will be described in detail with reference to FIG. 4.

In this example, relative rotation of the bell crank lever 10 with respect to the shew web 2b is prevented.

15 is a screw hole 2e provided in the shew web 2b.
Stopper bolt screwed together so that it can move forward and backward, 1
6 is a rock nut.

Therefore, the first arm 1 of the bell crank lever 10
When the end edge of the hook-shaped portion 10f' extending from 0a comes into contact with the upper end surface 15a of the bolt 15, rotation of the bell crank lever 10 is prevented.

At this time, if the pair of linings 2c and 3c have a large amount of remaining space, they can be used continuously by loosening the lock nut 16 and readjusting the stopper bolt 15 as appropriate, thereby reducing waste.

<B> Second Embodiment FIGS. 5 to 8 show a second embodiment in which the relative rotation of the bell crank lever 10 with respect to the show web is prevented as in the first embodiment. .

In this example, the hook-shaped portion 1 of the bell crank lever 10
0f is removed, and the intermediate portion of the stopper plate 17 having a corresponding hook-shaped portion 17a is attached to the pin 1.
1.

The other arcuate portion 17b of the stopper plate 17
is arranged between the bell crank lever 10 and the spring 13, its end is bent into a U-shape, and an angular tooth 17c is formed at the tip.

Since the spring 13 is offset by the U-shaped portion, the reaction force causes the chevron tooth 17c to
is constantly pressed against the bell crank lever 10, so that the stopper plate 17 can move together with the bell crank lever 10.

In the above-described configuration, when the hook-shaped portion 17a of the stopper plate 17 comes into contact with the show web, the rotation of the bell crank lever 10 is prevented. The stopping position of the bell crank lever 10 can be changed by inserting the bell crank lever 10 and disengaging the chevron tooth 17c, and then rotating the bell crank lever 10 around the pin 11 as a fulcrum.
The same effect as the first embodiment described above can be obtained.

<C> Third Embodiment FIG. 9 is a third embodiment, and shows a state in which relative rotation of the bell crank lever 10 with respect to the strut 8 is prevented.

In the same figure, an inclined long hole 10g is formed in the part of the second arm 10d of the bell crank lever 10 located on the back plate 1 side (see FIG. 2), and a roughly U-shaped U stop is formed in this part. 18 is snap-fitted.

Figure 10 is a developed view of the U stopper 18, the first
Figure 1 A, B, and C are the product drawings.

As shown in FIG. 10, the substantially trapezoidal wide side has a width A corresponding to the plate thickness of the bell crank lever 10.
Notches 18a and 18a' are provided with
As shown in FIG. 11, both sides thereof are bent outward to form claw portions 18b and 18b', which serve to prevent the ball from falling off after impact.

As shown in FIG. 9, the vicinity of the bottom of the U stopper 18 comes into contact with the bottom of the recess 8a formed in the strut 8 to prevent the bell crank lever 10 from rotating. 10g, the stopping position of the bell crank lever 10 can be changed freely.

<Effects of the Present Invention> As described above, the present invention enables effective utilization of lining resources with a simple structure.

Further, the present invention is not limited to the above-described embodiment, but may be constructed such that, for example, an eccentric cam having a predetermined rotational torque is attached to the U stopper 18 portion shown in FIG. or
It is also easily possible to attach the stopper to the strut.

In addition, this adjusting and stopping device can of course be used separately, and is not limited to leading/trailing type drum brakes, but can also be applied to two-leading brakes or dual-two leading brakes. It is possible.

[Brief explanation of drawings]

Figure 1: Front view of conventional drum brake, Figure 2
Figures: A cross-sectional view of - in Figure 1, Figure 3: A partially enlarged view of the gap adjustment and stop device when the lining wears out in Figure 2, Figure 4: An explanatory diagram of the first embodiment of the present invention. An enlarged view of the main parts when the lining is worn out, FIG. 5: An explanatory diagram of the second embodiment and a front view of the strut assembly, FIG. 6: A bottom view of the strut assembly, FIG. 7: FIG. - cross-sectional view of
Fig. 8: Enlarged view of the shaft stop portion of the stopper plate, Fig. 9: An explanatory view of the third embodiment and a front view showing the strut assembly when the lining is worn out, Fig. 10
Figure: Developed view of U stopper, Figure 11 A: Front view of U stopper, Figure 11 B: Left side view of U stopper, Figure 11 C: Plan view of U stopper 2, 3...Brake shoe, 2b, 3b...Show web, 2c, 3c...Lining, 2d...
...Opening, 2e...Screw hole, 4...Cylinder, 5
...Fixed anchor, 8...Strut, 8a...
Recessed portion, 9...Toothed element, 10...Bell crank lever, 10a...First arm, 10d...Second arm, 10f, 10f...Hook-shaped portion, 10g...Elongated hole, 11... Pin, 15... Stopper bolt, 1
7... Stopper plate, 17a... Hook-shaped part, 1
7c...Chevron tooth, 18...U stopper, 18b,
18b'...Claw part.

Claims (1)

[Scope of Claims] 1. A bell crank lever pivotally supported by a strut moves angularly in conjunction with a brake shoe to maintain a constant gap between the brake drum and the lining, and when the lining is worn to the limit. 1. A drum brake adjustment/stopping device for a drum brake having a stopping device for preventing rotation of a bellcrank lever, characterized in that a stop position for rotation of the bellcrank lever is made variable. 2. Claim 1, characterized in that the position of the stopper provided on the brake shoe or the bell crank lever is movable, thereby making the relative stopping position of the bell crank lever with respect to the brake shoe variable. Adjustment and stop device for drum brakes. 3. The drum brake according to claim 1, characterized in that the position of the stopper provided on the strut or the bell crank lever is movable, thereby making the relative stopping position of the bell crank lever with respect to the strut variable. Adjustment stop device.