Abstract: A continuously driven gear pump includes an internal bypass valve for selectively controlling the supply of pressurized fluid to a hydraulically actuated device. The internal bypass valve includes a movable spool which is spring-biased to a first position, wherein the flow of fluid is bypassed from the outlet port back to the inlet port, and no fluid is delivered to the actuated device. The spool has an internal passageway formed therethrough which permits a relatively small amount of fluid to pass from the outlet port back to the reservoir when the gear pump is operated in the bypass mode. To replenish this small amount of fluid which is returned to the reservoir from the outlet port, the gear pump draws a corresponding small amount of fluid to the inlet port. Thus, a small amount of fluid circulates between the gear pump and the reservoir when the gear pump is operated in the bypass mode. This circulation cools the pump without causing a significant load to be placed on the engine.

Abstract: A dry valve for a gear pump includes a piston having a valve head and a piston head mounted on the opposite ends of a piston rod. The piston is selectively movable between an opened position, wherein hydraulic fluid is permitted to flow from a reservoir to a pumping chamber of the gear pump, and a closed position, wherein such flow is obstructed. A source of pressurized air exerts a biasing force against the piston head to selectively move the piston. An outlet port of the gear pump is connected through a feedback passageway to the dry valve. The feedback passageway communicates with the side of a chamber in which the piston rod of the dry valve reciprocates between the opened and closed positions. When the dry valve is in the opened position, the pressurized fluid from the outlet port of the gear pump exerts a side-loading pressure against the piston rod, causing a frictional force to be generated between the piston rod and the piston rod chamber which resists relative movement.

Abstract: A gear is retained on a shaft over a reduced diameter portion of the shaft intermediate the ends thereof. An axially extending bore through the gear is received by the reduced diameter portion of the shaft, the portions of the shaft positioned outboardwardly of the gear defining axially opposed integral retention walls for axially fixing the gear on the reduced diameter portion.

Abstract: There is shown a pressure loaded external gear pump with a low pressure lubrication system. The low pressure lubrication system utilizes the viscous shear pumping effect which occurs between the shafts and bearings to draw fluid from the inlet port, circulate it past the bearings and then return it to the inlet port.

Abstract: The disclosure relates to improvements in pumps and motors of the gear type. The gear elements are arranged within the pump or motor housing so that the ends or the tips of the teeth are spaced out of fluid sealing relationship and not pressed into the surrounding chamber wall on the low pressure side of the housing. Rigid sealing members of limited circumferential extent having a curved sealing surface and planar support and side wall surfaces are seated in a recess in the housing at the high pressure side of the gears for the purpose of providing a fluid seal between the tips of the teeth in a limited region adjacent the opening in the housing which is at higher pressure. The sealing members are positioned in a recess in the housing and are configured to be resistant to bending and movement. The sole support for the shoes is provided by planar surfaces on the side pressure plates.

Abstract: Hydraulic equipment useful as a pump or motor intended for applications where hydraulic fluid is exposed to contamination by abrasive particulate material is disclosed. Leakage paths from the high pressure chamber in a gear pump or motor are provided with inserts of an abrasion and erosion resistant material at points where wear from abrasives in the hydraulic fluid is aggravated. In particular, the bearing surfaces of the pressure loaded side plates are provided with an insert of abrasion and erosion resistant material in the mesh region of the teeth. Erosion and abrasion resistant rings are located on the side plates in the region surrounding the openings for the shafts and extending interiorly of the tooth root circle to the journal bearings.Also disclosed are radial sealing shoes which are supported by the side plates and are radially urged into sealing relationship with the tips of the teeth by the pressure existing at the high pressure side of the gears.

Abstract: The disclosure relates to improvements in pumps and motors of the gear type. The gear elements are arranged within the pump or motor housing so that the ends or the tips of the teeth are spaced out of fluid sealing relationship and not pressed into the surrounding chamber wall on the low pressure side of the housing. According to the disclosure, sealing members of limited circumferential extent are provided in the housing at the high pressure side of the gears for the purpose of providing a fluid seal between the tips of the teeth in a limited region adjacent the opening in the housing which is at higher pressure. The sealing members disclosed are a pair of separate shoes located adjacent the high pressure opening. The sole support for the shoes is provided by the side pressure plates.

Abstract: A control system for plural motor driven pumps is disclosed. The control system includes a control valve which provides for unloading one pump by diverting the flow of operating fluid from that pump back to reservoir whenever the flow through the valve or the load pressure exceeds a preselected level.

Abstract: The disclosure relates to a control system for hydraulic pumps driven by the engine of a vehicle or the like and used for operating an auxiliary mechanism such as a vehicle mounted implement, a power steering system or the like. The disclosed system includes means for interrupting the flow of operating fluid to the pump during periods of time when the output of the pump is not required. With the pump inlet closed, all of the hydraulic fluid on the suction side is immediately pumped out the pump discharge, leaving only a small amount of residual oil on the surface of the working parts to provide lubrication. A valve is provided to prevent fluid from returning to the pump because of downstream pressure in the circuit. Control means, utilizing pressure downstream from the pump, for operating the valve in the inlet of the pump are disclosed.