Patent ID: 7204783

Claim:
A toroidal type continuously variable transmission comprising: an input disc adapted to be driven by prime mover of a motor vehicle; an output disc coaxially arranged with the input disc, the output disc being adapted to be constantly connected to road wheels of the vehicle; power rollers each being interposed between the input and output discs to transmit a torque from the input disc to the output disc through the power rollers; trunnions rotatably supporting the power rollers respectively; a main oil pump powered by the prime mover; a line pressure producing circuit which produces a line pressure by adjusting an oil pressure produced by the main oil pump; a hydraulic servo mechanism powered by the main oil pump, the hydraulic servo mechanism inducing a speed change between the input and output discs by actuating the trunnions in such a manner as to pivot a rotation axis of each power roller between a neutral position where the rotation axis intersects a common axis of the input and output discs at right angles and an offset position where the rotation axis is shifted toward a shaft axis of the trunnion while being offset relative to the common axis; a forward speed control valve through which the line pressure passes when the vehicle moves forward; a reverse speed control valve through which the line pressure passes when the vehicle moves backward; a feedback mechanism which feeds back a progress of the speed change to the hydraulic servo mechanism so that when a practical speed change ratio between the input and output discs becomes in coincidence with an instructed ratio, each power roller is returned to the neutral position; a forward/reverse switching valve which selectively feeds the line pressure to one of the forward and reverse speed control valves in accordance with a direction in which the vehicle moves, the forward/reverse switching valve having a line pressure inlet part to which the line pressure is applied; an extra oil pump powered by the road wheels; and an extra hydraulic circuit which feeds an oil pressure produced by the extra oil pump to the line pressure inlet part of the forward/reverse switching valve.