Identification and quality requirements of brake shoe return spring

The brake shoe return spring uses the tension of the spring to make the brake shoe quickly return to its original position after working to ensure the continuous braking effect. It is a hook type stretch spring made of cold winding spring steel wire.

Quality requirements for brake shoes:

1) Materials

The spring material shall be made of Ⅰ and Ⅱ carbon spring wire wound.

2) Hardness

After quenching, tempering treatment of cold coil spring, its hardness value is selected in the range of 44-52HRC. In special cases, the hardness value can be expanded to 55HRC.

3) Appearance quality requirements

The surface of the spring should be blackened, the surface of the steel wire should be smooth, no cracks, oxidation, rust and other defects are allowed; The bend of the hook shall not have scars; Cold coil springs are not allowed to have individual indentations, pits and scratches that are deeper than half the diameter tolerance of the material.

4) The tensile spring with the working limit load requirement is not allowed to have permanent deformation under the working limit load.