GB868636A - Improvements relating to hydrostatic power transmissions - Google Patents

Abstract

868,636. Hydraulic apparatus. AUSTIN MOTOR CO. Ltd. May 27, 1960 [June 10, 1959], No. 19837/59. Class 69 (2). A variable-ratio hydrostatic power transmission, such as the type in which one or more positive-displacement pumps transmit power to one or more positive-displacement motors and in which a change of ratio is effected by an hydraulic circuit controlling the supply of fluid pressure from an auxiliary pump to two or more hydraulic feeds connected to two or more hydraulic cylinders, comprises pressure-responsive valve means enabling the working circuit of the transmission to be primed by fluid pressure from whichever of the feeds is at the higher or highest pressure. The pressure-responsive valve means may consist of spring-loaded one-way valves V1, V2 having their inlets 5, 6 connected to the feed lines L, R leading to the forward low-speed cylinder 2C and reverse cylinder RC, and their outlets 3, 4 connected to a priming line P leading to the working circuit of the transmission. The arrangement of the control circuit is such that when the transmission is in reverse, the forward low-speed feed line L is pressurized and fluid therein passes through the valve V1 to the priming line P, and vice versa. The valves V1, V2 may be connected to the high-speed line H and the low-speed line L, or three valves may be provided connected to the high. low and reverse lines, the line having the highest pressure serving to prime the working circuit. The spring-loaded valves may be replaced by a shuttle-valve.