GB735977A - Improvements in or relating to hydraulic transmission - Google Patents

Abstract

735,977. Variable-speed gearing. CARLSON, R. E. Aug. 18, 1953, No. 22761/53. Class 80 (2). [Also in Group XXIX] A hydraulic transmission for coupling a driveshaft to a selected one of two gear trains driving a driven shaft comprises two sets of radially dis-. posed cylinders and pistons mounted to rotate with the drive shaft, the pistons of a set reciprocating when flow of liquid is permitted between the cylinders of that set, but being locked when flow of liquid is prohibited and thereby driving the output shaft through the corresponding gear train. If both sets of pistons are locked at the same time the end gears of the trains rotate solid with a gear-wheel on the driven shaft to give a 1: 1 drive. Carriers 15, 16 provided with radially disposed cylinders 17, 50 are fast on a drive shaft 10. The cylinders 17 are provided with ports 85 opening into a bore 86, pistons 18 being free to reciprocate when the ports are open. Each piston 18 is connected by a crank 19 to a ring 22 which can rotate relative to an eccentric surface 23 of a member 24 when the ports are open. On closing the ports the pistons are locked and member 24 is rotated. Member 24 is coupled to a gear train 36, 37, 39, gear wheel 39 meshing with a gear 40 fast on the driven shaft 11. Carrier 16 is provided with similar cylinder and piston devices and serves to drive a gear train 61, 62, 64, gear 64 meshing with the gear 40. A valve 93 is provided with lands for controlling the ports 85, 87, and is actuated by a lever 104 so that, in one position, the ports of both sets of cylinders are open, and the transmission is in neutral. On shifting the lever 104 the ports 87 of the set of cylinders 50 are closed, and the shaft 11 is driven by the gear train 61, 62, 64. A further shift of the lever opens ports 87 and closes ports 85 and shaft 11 is driven by the other gear train. A further shift of the lever closes both sets of ports, and gears 39, 64 rotate solid with gear 40. Gears 39, 64 are mounted on a carrier 70 which is rotatably mounted on the shaft 11 and provided with an over-running clutch securing it to a fixed frame member 76. At least one of the pistons in each set is provided with a flap valve permitting oil in a space 90 to enter the cylinder circuit to make up any oil which may have leaked from that circuit. A simple form of automatic governor control or torque responsive mechanism may take the place of the lever 104.