To provide a power transmission device for avoiding the breakage of structural elements on the downstream side of a power transmission passage (on the side of an output member) even when an overload (impact torque) is momentarily given from the side of an input member.
The power transmission device has a pressure contact assisting cam having a clutch member side cam face and a pressure member side cam face facing each other for increasing the pressing force of a driving side clutch disc 6 against a driven side clutch disc 7 in the state where a rotating force inputted to the input member is transmitted to the output member. The power transmission device is equipped with a disc spring 11 as a limiter mechanism for canceling a load when imparted via the pressure contact assisting cam while reaching a predetermined value, to prevent an increase of the pressing force of the driving side clutch disc 6 against the driven side clutch disc 7.
KASHIWAGI SATOSHI
NONAKA MASAYUKI
