JPH0512500Y2 - - Google Patents

Description

[Detailed description of the invention] [Purpose of the invention] (Field of industrial application) This invention relates to a drum brake provided with a gap adjustment mechanism.

(Prior art) Some drum brakes with a gap adjustment mechanism have a strut C disposed between a pair of drum brakes A and B, with one end supported by a lever D, as shown in Figure 7. .

In this drum brake, the strut C and lever D are pulled toward the brake shoe A by a spring E. For this purpose, lever D
Before assembling the connecting piece F that supports the backward movement of the
The lever D is moved back toward the brake shoe A by the force of the spring, as shown by the dashed line, and is positioned so as to overlap the brake shoe A.

Therefore, when assembling the connecting piece F, first move the lever D against the spring E in the direction indicated by the arrow a in the figure.
As shown in the figure, it has to be rotated inward and held, making assembly work difficult. Also, the 8th
As shown in the figure, there was a risk of assembling the connecting piece F with the lever D placed below the brake shoe A by mistake.

(Problem to be solved by the invention) As mentioned above, in conventional drum brakes, the lever must be rotated against the spring and the connecting piece must be assembled while being held in that position. It took time to assemble and required skill to assemble, resulting in poor assembly performance. Furthermore, if the lever is not held properly, there is a risk that the connecting piece may be assembled with the lever still placed below the brake shoe.

The object of this invention is to solve these problems and provide a drum brake that has good maintainability during assembly and eliminates the possibility of assembling the connecting piece with the lever placed in the wrong position.

[Structure of the idea]

(Means for solving the problem) This invention was made in order to solve the above-mentioned problem.It is a lever that holds one end of the gap adjustment mechanism that restricts the inward movement of the brake shoe. and a connecting piece that is provided between the back of the lever and the brake shoe and supports the backward movement of the lever, in which the lever is rotated on a support shaft provided at the end of the brake shoe. A protrusion that can come into contact with the back surface of the brake shoe is provided on the lever between the support shaft and the connecting piece so that the lever can be freely attached and the tip of the lever is always located inside the inner edge of the brake shoe. A drum brake, characterized in that the protruding portion is separated from the rear surface of the brake shoe when the connecting piece is assembled.

(Function) In the drum brake with the above configuration, by providing the lever with a protruding part that comes into contact with the back of the brake shoe, it is possible to prevent the lever from moving backwards excessively. The tip protrudes inward from the inner edge of the brake shoe. Therefore, when assembling the connecting piece,
The lever and connecting piece can be assembled in the specified position by simply inserting the connecting piece from the tip of the lever so that it fits between the lever and the brake shoe, ensuring that incorrect assembly of the connecting piece is prevented. This improves assembly workability.

Further, since the protruding portion of the lever is separated from the back surface of the brake shoe when the connecting piece is assembled, it is possible to eliminate the audible adjustment phenomenon of the gap adjustment mechanism that occurs between the brake shoe and the brake drum.

(Embodiment) Hereinafter, an embodiment of the drum brake according to the invention will be described with reference to the accompanying drawings.

FIG. 1 shows a plan view of a drum brake, which includes a pair of brake shoes 1 and 2. As shown in FIG. Brake shoes 1 and 2 are brake shoes rims 1a and 2a, respectively.
and shew webs 1b and 2b are formed into a substantially T-shaped cross section by welding or the like.
Linings 1c and 2c are attached to the outer peripheral surfaces of a and 2a.

One end of each of the brake shoes 1 and 2 is in contact with a fixed anchor 4 fixed to a back plate 3, and the other end is in contact with a cylinder 5, as shown in FIG. Each brake shoe 1, 2
Return springs 6a and 6b are provided between them to constantly pull the brake shoes 1 and 2 inward.

A lever 7 is rotatably attached to the end of one brake shoe 1 on the cylinder 5 side by a pin 8 serving as a support shaft. An end of a strut 9 that adjusts the gap between the brake shoes 1, 2 and a brake drum (not shown) is engaged in the middle of the lever 7. A toothed element (pinion) 1 is installed in the middle part of the strut 9 as a gap adjustment mechanism.
0 is fixed. At the other end of strut 9,
A bell crank 11 that engages with the other brake shoe 2 is rotatably supported by a pin 12.

The bell crank 11 includes an arm portion 11a that engages with a fitting hole 2d provided in the brake shoe 2, and a toothed (rack) portion 11b that meshes with a toothed element (pinion) 10. A spring 13 is latched to the toothed element 10, the other end of the spring 13 being latched to the brake shoe 1 and pulling the strut 9 towards the brake shoe 1.

When the linings 1c, 2c are worn and the amount of expansion of the brake shoes 1, 2 exceeds a predetermined amount, the toothed element 10 is pulled leftward by the spring 13 in FIGS. attached element 10
The engagement between the bell crank 11 and the bell crank 11 is released. At this time, as the brake shoes 1 and 2 expand, the bell crank 11 is pulled by the brake shoes 2 and rotates counterclockwise in FIG. The length between them can be increased depending on the outer peripheral shape of the toothed portion 11b. At this time, since the backward movement of the lever 7 is restricted by the strut 9, the brake shoes 1 and 2 do not move backward unnecessarily.
The gap between the drum and the drum can be maintained at an appropriate size.

Figure 3 shows the assembled state of the brake shoe, with a hold pin 1 attached to the back plate 3.
4 is implanted (fixed), and this hold pin 14 passes through the shew web 1b. A connecting piece 15 is locked to the tip of the hold pin 14. The connecting piece 15 is formed of a leaf spring having a substantially U-shaped cross section, and presses and fixes the brake shoe 1 to the back plate 3 side. A tongue portion 15a is integrally provided on the connecting piece 15, and this tongue portion 1
5a By bringing the lever 7 into contact with the lever 7, the lever 7
The brake shoe 1 and the brake shoe 1 are designed to move almost as one.

When the lever 7 is assembled, the spring 13
Under the action of the spring, the strut 9 is pressed toward the brake shoe 1, but the protrusion 7a provided on the lever 7 abuts against the rear surface of the brake shoe 1, causing unnecessary brake shock. It is designed so that it does not rotate towards the U1 side. Therefore, the tip 7b of the lever 7 is located inside the inner edge of the brake shoe 1 when the connecting piece 15 is assembled, as shown in FIG. When assembling the connecting piece 15, place the connecting piece 15 between the lever 7 and the brake shoe 1, and slide it along the brake shoe 1 as shown by arrow b in FIG. 15, the lever 7 can guide the connecting piece 15 to a predetermined position while rotating counterclockwise against the spring force of the spring 13.

Therefore, there is no need to rotate and hold the lever 7 inward as in the conventional case, and the connecting piece 15 can be assembled in a predetermined position with a simple operation. In addition, since the lever 7 does not unnecessarily go under the brake shoe 1 due to its abutting portion 7a, the connecting piece is assembled while the lever 7 is placed under the brake shoe 1. There is no risk of it happening.

In this embodiment, the connecting piece is an example of a spring member having a substantially U-shaped cross section, but instead of the spring member having a substantially U-shaped cross section, a coil spring 2 is used as shown in FIG.
0, the receiving washer (cup washer) 21 of the coil spring 20 can also be used as a connecting piece. In addition, as shown in FIG. 6, a tapered surface 22 is actively formed at the tip of the lever 7A, and using this tapered surface 22, while prying the show hold spring 15 in the direction of arrow c, You may insert it into

[Effect of idea]

In the drum brake according to this invention, when assembling the connecting piece, the tip of the lever is located inside the inner edge of the brake shoe, so there is no need to rotate and hold the lever inward, and the connecting piece can be assembled. The connecting piece can be easily assembled by simply inserting it while sliding it along the brake shoe. In addition, since the lever is in contact with the back of the brake shoe by the abutment part, it will not rotate to the bottom of the brake shoe unnecessarily, and the lever will not be rotated by mistake when assembling the connecting piece. There is no risk of assembling the connecting piece while it is placed below the brake shoe.

Furthermore, since the protruding portion of the lever is separated from the back surface of the brake shoe when the connecting piece is assembled, it is possible to eliminate the over-adjustment phenomenon of the gap adjustment mechanism that occurs between the brake shoe and the brake drum.

[Brief explanation of the drawing]

Fig. 1 is a plan view of the drum brake according to this invention, Fig. 2 is a sectional view taken along line A-A in Fig. 1, Fig. 3 is a partially enlarged view showing the assembled state of the brake shoe, and Fig. 4 is a plan view of the drum brake according to the invention. The figure is a partially enlarged view showing how to assemble the connecting piece, Figures 5 and 6 are views showing other assembled states of the connecting piece, Figure 7 is a plan view showing a conventional drum brake, and Figure 8 is a plan view showing a conventional drum brake. This figure is a partially enlarged view showing the assembled state of the brake shoe shown in FIG. 7. 1, 2... Brake shoe, 5... Cylinder,
7, 7A... Lever, 7a... Contact portion, 9... Strut, 13... Spring, 15... Connecting piece.

Claims (1)

[Scope of utility model registration request] While regulating the inward movement of the brake shoe
In a drum brake that is provided with a lever that holds one end of the adjustment mechanism and a connecting piece that is provided between the back of the lever and the brake shoe and supports the backward movement of the lever, the lever is attached to the end of the brake shoe. The lever is rotatably attached to a provided support shaft, and the lever has a protrusion that can come into contact with the back surface of the brake shoe so that the tip of the lever is always located inside the inner edge of the brake shoe. A drum brake, characterized in that the protrusion is provided between the support shaft and the connecting piece, and is separated from the back surface of the brake shoe when the connecting piece is assembled.