Piston seal and disc brake using the piston seal

摘要

A piston seal of a disc brake can stabilize the amount of rollback of a piston by reducing thermal expansion and a decrease in modulus of elasticity of the piston seal caused by an increase in temperature, thereby preventing a driver from feeling that the brake operation is unnatural. The piston seal is formed of a rubber composition in which at least 100 parts by weight or more of carbon black is added to 100 parts by weight of ethylene propylene rubber.