Abstract: An improved commutator for a gerotor-type hydraulic pump or motor of the type having an orbiting outer or inner gear. Such pumps or motors require a commutator having a circular array of alternating inlet and outlet openings adjacent to a rotating valve plate which regulates flow to the gerotor gears. The commutator of the present invention has a chambers section and a fluid pathways section. The chambers section has a radially inner and a radially outer chamber disposed therein radially beneath the inlet port and outlet port of the pump or motor, also disposed in the chambers section. The radially outer chamber and radially inner chamber are each connected to one of the inlet and outlet ports. The pathways sections has the circular array of alternating inlet and outlet openings therein and includes fluid pathways which connect these inlet and outlet openings, respectively, to one of the radially inner and radially outer chambers of the chambers section.

Abstract: An improved, high-pressure fluid draining, internal gear hydraulic device of the type having a rotatable valve plate which selectively communicates inlet and outlet ports of a commutator with opening and closing fluid chambers between internal and external gear. The valve plate has radially extending drain ports which drain high pressure fluid from the area inside the valve plate to a check valve system outside the valve plate. This check valve system can drain to a low pressure fluid port of the device such as the inlet or outlet of the pump.

Abstract: A reinforced internal gear machine of the type having variable displacement fluid chambers formed between an orbiting outer gear and a rotating inner gear. The orbiting outer gear is retained in its orbiting motion by a plurality of roller dowells closely fitting in a locating ring disposed radially outside the outer gear and extending therefrom to be received in arcuate recesses on the radial outside of the outer gear as it orbits. The locating ring is connected to an end piece of internal gear machine along a plane of torsional stress and this connection is reinforced by this invention. The reinforcement is made by the end piece having recesses disposed coaxially with the roller dowells and the roller dowells extending closely within these recesses from the cover. The roller dowells thus extend across the plane of torsional stress for reinforcement.

Abstract: An improved rotary valve plate and internal gear machine wherein an imbalance across the rotary valve plate due to high pressure fluid on the commutator side of the valve plate being opposite low pressure fluid in the variable displacement chambers on the gear side of the valve plate is balanced by a recess which extends around the periphery of the valve plate and receives fluid from the gear side of the valve plate to urge the valve plate toward the commutator. Preferably, the internal gear machine is of a type with an orbiting outer rotor orbiting in an annulus with intermediate pressure fluid in the annulus. The recess on the gear side of the valve plate is disposed to receive intermediate pressure fluid from the annulus.

Abstract: A gerotor device wherein a body (10) includes high pressure ports (20) that communicate with an inlet (12) and low pressure ports (22) that communicate with an outlet (14). An inner member (42) and an outer member (40) cooperate to define pressure chambers (52) that increase and decrease in volume as the member (42) orbits and rotates. A rotary valve (62) selectively connects pressure chambers (52) to pressure ports (20) and (22) to convert between mechanical torque and fluid pressure. Cavities (75) and (77) are provided adjacent rotary valve (62) to hydraulically balance the valve.