Power transmission system for vehicles

摘要

A power transmission system for vehicles comprising a driving member connected to an engine crankshaft, and a driven member connected to a driving wheel, the driving and driven members being connected with each other via a one-way clutch and a friction clutch which are disposed in parallel to each other. The one-way clutch is in a connected state when a forward load is applied to the engine, and in a disconnected state when a back load is applied to the engine. The friction clutch is operated to slip when it receives a torque greater than a predetermined value. With this arrangement, power is normally transmitted from the engine to the driving wheel through the one-way clutch and the friction clutch without any substantial power loss whereas a back load to be transmitted from the driving wheel to the engine in excess of a predetermined value is interrupted by the disconnection of the one-way clutch and the slipping of the friction clutch to prevent the engine from being subjected to any excessively great back load.