Introduction of Trailer Brake Shoes

A trailer brake shoe refers to a part that expands outward under the force of camshaft or push rod to press the brake drum and play the role of braking. It is installed on the axle through the brake bracket. It is one of the key safety components in the automobile braking system.

As shown in Figure 1 below. A brake shoe is a matching part of internal tension shoe friction brakes. And the other matching part is a brake drum. When working, it bears the thrust of camshaft, the reverse force, tangential force and support reaction force of external brake drum. It shall have the strength and appropriate stiffness, and the supporting brake lining on the brake shoe shall have as high and stable friction coefficient as possible.

Brake shoes are widely used on axles of semi-trailers.

As shown in Figure 2 below. The brake shoe assembly is mainly composed of brake shoes, brake linings and rivets. The brake linings are riveted to the brake shoes through rivets, and the brake shoes are composed of rib plates and panels.

It is mainly introduced from the following aspects:

1. Classification of brake shoes

(1) Casting brake shoes

As shown in Figure 3 below. This kind of brake shoe is integrally formed by casting process, which has the following advantages over pressing and welding brake shoe:

① Good product consistency. The casting process can ensure the consistency of products.

② The product has strong rigidity. This can avoid the problem of weak brakes to a certain extent. Heavy-duty trucks generally use cast brake shoes.

With the further development of automobile lightweight and the improvement of environmental protection requirements, the brake shoe is gradually converted to pressing and welding process.

(2)?Pressing and welding brake shoes

As shown in Figure 4 below. This kind of brake shoe is made of steel plates under pressing and welding process, with high market share. Compared with the traditional casting process, it has the following advantages:

① Light weight. Under the same specifications, the brake shoe is about 20% lighter than the cast brake shoe, which is more in line with the development trend of automobile lightweight.

② Better performance. Because the pressing and welding brake shoes are made of steel plates, the steel plates have a certain elasticity. During braking, the brake lining fits more closely with the brake drum, and the braking effect is better. At the same time, due to the light weight of the brake shoe, the braking reaction time is shortened.

③ The unequal thickness design of brake lining can be realized. The brake lining is more fully utilized to improve the service life of the brake lining.

④ Low manufacturing cost and high production efficiency. The pressing and welding process is relatively simple and the processing cycle is short, which can avoid the production pressure required by mass casting blanks.

⑤ Good social benefits. Pressing and welding process replaces casting process, which has low environmental pollution only.

2. Technical parameters of brake shoes

As shown in Figure 5 below. The main technical parameters of brake drum shoes are as follows:

(1) A：Center distance between support pin and roller pin

(2) B：Brake shoe width

(3) H：Center height

(4) R：Radius of braking surface

(5) D1：Diameter of support pin

(6) D2：Diameter of roller pin

3. Selection of brake shoes

How to select the brake shoe correctly, it can be determined from the following aspects:

(1) Determine the products according to the OEM numbers of automobile manufacturers, axle manufacturers or brake shoe manufacturers.

See Table 1.below for Common Brake Shoe OEM Numbers of Well-known Manufacturers:

(2) Determine the products according to the basic parameters of brake shoes

Referring to figure 5, the technical parameters of common brake shoes are shown in Table 2 below.

(3) Determine the products according to the brake shoe samples or drawings.

4. Brake shoe maintenance instructions

In order to achieve the longest service life and best service performance of the brake shoes, regular maintenance shall be carried out in accordance with the maintenance manual of the vehicle manufacturer or axle manufacturer.

5. Brake shoe warranty description

The quality warranty of brake shoes of heavy duty vehicles is generally as follows:

① Brake shoes for semi trailers : 3 years or 500,000 km

② Brake shoes for heavy duty trucks: 2 years or 500,000 km.

Quality warranty is generally limited to use on expressways or ordinary roads. It does not include normal wear and tear, improper use, improper installation, traffic accident, improper maintenance or any other situation that may be regarded as causing product failure. The specific situation shall be subject to the manufacturer's instructions.

Note: Brake linings are vulnerable parts and are not covered by the warranty.

6.?WONDEE brake shoes selection table

The WONDEE brake shoe selection table is shown in Table 3 below:

Compiled by ?WONDEE Autoparts