Coupling device

摘要

A coupling device comprises first and second sliding surfaces (S2, S1) being located between first and second rotary members (30a, 30b; 130a, 130b) which are rotatable relative to each other. The first and second sliding surfaces (S2, S1) friction engage with each other to transmit torque between the first and second rotary members. A thin diamond-like carbon film (D) is formed on the first sliding surface (S2).