Abstract: The present invention is directed to a compact, lightweight and inexpensive hydrostatic transmission which in the preferred form has a variable displacement and reversible pump placed in side-by-side relationship with a fluid motor and wherein the transmission has a multisection housing with a uniform width center section forming both the pump chamber and the motor chamber. The fluid capacity of the pump and the fluid capacity of the motor are proportional to their widths and the ratio of the fluid capacity remains constant as various width center sections are used.

Abstract: A reversible flow vane pump having a pump case with a pump chamber in which a rotor is mounted. The rotor has outwardly-opening slots which carry vanes which engage a cam ring and with fluid chambers between vanes. The cam ring can be adjusted to positions at either side of a neutral position to provide reversible flow operation between a pair of ports, with variable volume control. The ports are arranged to increase the length of time in which a port communicates with an intervane fluid chamber which is of decreasing volume for increased utilization of fluid being pressurized. A port which functions as an inlet port in a predominant mode of operation of the pump has an extension effective to increase the length of time in which an intervane fluid chamber of increasing volume can be filled with fluid.