The brake shoe return spring uses the pull force of the spring to quickly return the brake shoe to its original position after working to ensure the effect of continuous braking. It is a hook-type tensile spring made of cold winding of spring steel wire.
Quality requirements for brake shoe sleeve shoes:
(1) Material The spring material should be wound by group I and II carbon spring wire.
(2) Hardness The hardness value of the cold-coiled spring after quenching and tempering treatment 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, and defects such as cracks, oxide scale, and rust are not allowed; There must be no scars at the turn of the hook; Cold-coiled springs do not allow individual indentations, pits and scratches that are half the material diameter tolerance.
(4) Tensile springs with working limit load requirements are not allowed to have permanent deformation under working limit load.
