CONTINUOUS VARIABLE TRANSMISSION

PURPOSE:To enhance the efficiency of a continuous variable transmission by using a pilot pressure driven type high speed clutch and by providing a lock mechanism for the input and output shafts of one of fluid pump/motors so that the other one races when it receives a pilot pressure. CONSTITUTION:In a high speed mode in which a high speed clutch 15 is connected, when the speed reaches a predetermined high speed range, a lock mechanism 33 is actuated to lock one 7 of fluid pump/motors. Further, a pilot pressure for changing over the connecting condition of the high speed clutch 15 and a pilot pressure for changing over the operating condition of the lock mechanism 33 are delivered to a logic valve 45. As a result, the valve 45 feeds a pilot pressure P into the other one 8 of fluid pump/motors which therefore races with a small friction resistance. Accordingly, in a lock-up condition, the fluid transmission system constituted by both fluid pump/motors 7, 8 is substantially completely isolated from a power transmission path, and therefore, power is transmitted only through a differential mechanism.