FRICTION TRANSMISSION DEVICE

PROBLEM TO BE SOLVED: To improve durability of input and output members in a friction transmission device to transmit power by friction between the input and output members which are in rolling contact. SOLUTION: A cross sectional form of a roller 10 to get in rolling contact with a disc 16 perpendicular to its rolling direction is set in a non-arc form such as a hyperbolic sine form (dashed line) in which contact stress is more uniform in a range C where the disc 16 gets in contact with the roller 10. Outside the contact range, it is roughly formed in an arc form (broken line). At an adjoining part to the contact range, especially, it is formed to be smoothly changed from the non-arc form into the arc form. Reduction of roller width due to the non-arc form is thus restricted. internal stress is reduced, and diffusion of heat generated at the contact part becomes easier.