Abstract: A port plate for a swashplate type axial piston pump is described herein. The port plate includes an inlet port, a discharge port, and a first metering notch in fluidic communication via a first passage with a metering notch area adjustment valve configured to adjust the effective area of the metering notch. The first metering notch is disposed at a leading edge of one of the inlet port or the discharge port.

Abstract: A port plate for a swashplate type axial piston pump is described herein. The port plate includes an inlet port, a discharge port, and a first metering notch in fluidic communication via a first passage with a metering notch area adjustment valve configured to adjust the effective area of the metering notch. The first metering notch is disposed at a leading edge of one of the inlet port or the discharge port.

Abstract: An apparatus for charging a hydraulic system from a fluid reservoir includes a pump having an inlet and an outlet, a first conduit fluidly connected to the pump inlet and fluidly connectable to the fluid reservoir, and a second conduit fluidly connected to the pump outlet and fluidly connectable to the system. The apparatus also includes an accumulator operatively connected to the second conduit, a third conduit interconnecting the first conduit and the second conduit, and an electrically actuated fill valve operatively disposed in the third conduit.

Abstract: An apparatus for charging a hydraulic system from a fluid reservoir includes a pump having an inlet and an outlet, a first conduit fluidly connected to the pump inlet and fluidly connectable to the fluid reservoir, and a second conduit fluidly connected to the pump outlet and fluidly connectable to the system. The apparatus also includes an accumulator operatively connected to the second conduit, a third conduit interconnecting the first conduit and the second conduit, and an electrically actuated fill valve operatively disposed in the third conduit.

Abstract: A variable displacement hydrostatic pump (11) having its displacement varied by a controller (17) in response to movement of a manual control lever (95) from a neutral position (FIG. 1). The vehicle has at least one other device (125,127) which provides an electrical output signal (133) indicating when operation of the pump (11) is "acceptable", in terms of either vehicle performance or operator safety. Associated with the control lever (95) is an input shaft (103) defining at least one stop surface (121,123). A solenoid assembly (109) has a moveable plunger (111), disposed adjacent the stop surfaces, and moveable between a retracted position (FIG. 4a) and an extended position (FIGS. 2 and 4), engaging one of the stop surfaces, when the output signal (133) indicates that operation of the pump is not acceptable.

Abstract: A control system (33, 41) is disclosed of the type used to control the displacement of a variable displacement pump (11) having stroking cylinders (25, 27). The control system includes a pair of ON-OFF electromagnetic valves (49, 51) and a proportional valve (85). When a first direction of operation is selected, a first direction command signal (43) is transmitted to the first ON-OFF valve (40) such that control pressure from the charge pump (17) flows through the valve (49), then through the proportional valve (85) and through the valve (51) to the reservoir (75) until the proportional valve (85), in response to an increasing displacement signal (47), moves from its minimum displacement position (FIG. 1) toward a position corresponding to the desired displacement of the pump.

Abstract: A closed-loop hydrostatic transmission is disclosed of the type with a fluid pump (10) and a fluid motor (12), both of which are variable displacement. A pair of stroking cylinders (36,38) varies the displacement of the motor between minimum displacement and maximum displacement, under the control of a motor stroking valve (70) which includes a stroking valve member (90) movable in response to changes in fluid pressure in a pressure chamber (110). The displacement of the pump is controlled by a main controller (50) in response to movement of an input handle (60). Whenever the handle (60) is moved to the neutral position, a neutral switch (122) is closed, thus generating a neutral signal which is transmitted to an electromagnetic valve member (114), which controls the pressure in the fluid pressure chamber (110) to command the motor to maximum displacement.