Brake shoe return position spring is the use of spring tension to make the brake shoe iron work quickly back to the original position, in order to ensure the effect of continuous braking. It is a hook type extension spring made of cold winding spring steel wire.

Quality requirements of brake shoe:

1) material

Spring material should be Ⅰ, Ⅱ group carbon spring steel wire winding.

2) hardness

The hardness value of cold coil spring treated by quenching and tempering is selected within the range of 44-52hrc. In special cases, the hardness value can be extended 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 skin, rust and other defects are allowed; No marks shall be found at the bend of the hook; Cold coil springs are not allowed to have individual indentations, pits, and scratches with a depth greater than half the material diameter tolerance.

4) the tensile spring required by the working limit load is not allowed to have permanent deformation under the working limit load.