Infinitely variable transmission for a vehicle

Claim 1

A continuously variable power transmission mechanism adapted to delivery driving torque from an internal combustion engine to a driven shaft comprising: an input shaft arranged coaxially with respect to said engine; a start-up clutch adapted to connect said engine to said input shaft; a primary sleeve shaft mounted for rotation about said input shaft; a drive pulley connected to said primary sleeve shaft; planetary gearing connecting drivably said input shaft and said primary sleeve shaft including a reversing gearset with a sun gear, a ring gear, a planet pinion carrier and compound plane pinions journalled on said carrier, said planet pinions having two engageable sets, the pinions of one set engaging said ring gear and the pinions of the other set engaging said sun gear; clutch and brake means for selectively anchoring said ring gear and for connecting said carrier and ring gear together to effect forward drive and reverse drive; said start-up clutch comprising an annular piston located within an annular cylinder and defining therewith a pressure chamber, a friction disc having friction surfaces, said friction disc being positioned between an annular friction surface of said start-up clutch and said piston; said start-up clutch annular cylinder comprising a pair of radially disposed wall members in abutting side-by-side relationship, and radial grooves formed in one of said wall member to define radial fluid pressure distribution passages extending to said pressure chamber.