Abstract: A variable displacement hydraulic pump including a control actuator configured to interact with a movable displacement control member to control the displacement of the pump; and a displacement control valve assembly configured to provide mechanical feedback control of positioning of the control actuator and thereby the displacement control member. The displacement control valve assembly includes a control valve member that is movable within a fluid flow path of the control valve assembly to control a flow of fluid to or from the control actuator. The control valve assembly includes a first valve part, a second valve part, and a biasing member configured to selectively position respective one or more portions of the first and second valve parts relative to each other to open or close a vent flow passage in response to an operating state of the pump.

Abstract: A hydraulic axial piston pump is designed with a secondary swashplate angle for providing improved performance and life. The secondary swashplate angle produces a sideload on the swashplate that is reacted by the pump's housing. A hydrostatically balanced thrust bearing is used to counteract the sideload produced by the secondary swashplate angle. The bearing design includes a tiltable pad or shoe supplied with pressurized fluid from the pump's discharge port. The same fluid that supplies the tiltable pad may also supply the pump's cradle bearings.

Abstract: A hydraulic axial piston pump is designed with a secondary swashplate angle for providing improved performance and life. The secondary swashplate angle produces a sideload on the swashplate that is reacted by the pump's housing. A hydrostatically balanced thrust bearing is used to counteract the sideload produced by the secondary swashplate angle. The bearing design includes a tiltable pad or shoe supplied with pressurized fluid from the pump's discharge port. The same fluid that supplies the tiltable pad may also supply the pump's cradle bearings.

Abstract: Improvement, in hydraulic systems, such as for vehicle transmissions and the like, in the form of a hydraulic reservoir with integrated heat exchanger having fluid supply/return and fluid return ports, including a central section, having inner and outer shell portions with a first gap therebetween, the outer shell being provided with a plurality of radially-spaced, external cooling fins, longitudinally-directed for the length of the central section; the ends of the latter being closed off via respective bottom and top cap portions, thereby defining a central fluid cavity, the top cap portion having spaced outer and inner cap portions, with a second gap therebetween, with a fluid inlet port, in the outer cap portion, directing incoming fluid from the second gap into and through the entire length of the first gap before entering the central fluid cavity, thereby maximizing heat transfer from the fluid via the plurality of cooling fins.

Abstract: In a variable displacement type hydraulic pump/motor assembly including at least one internally movable component, such as a yoke, a swashplate, and the means for moving the swashplate, the improvement includes imparting on this component absolute location indicia markings and the addition of an optical/electronic sensor unit capable of reading such indicia markings fixedly located on a housing of the pump/motor assembly and including an optical read head extending into the housing interior and located at a spaced distance from the indicia markings for reading same, relative to a reference location, and producing a signal indicative of the absolute position of the movable component. The signal can then, in turn, be used for controlling the displacement of the pump/motor assembly. A method for determining the absolute component position is also set forth.