Abstract: A variable displacement axial piston pump has a plurality of piston bores each connected to an inwardly angled fill port. The fill ports extend from the piston bores inwardly to the working face of the barrel to reduce the diameter of the fill circle of a pump. This decreases the velocity that must be attained by incoming fluid to thereby increase the operating speed at which the pump may be driven where the pump is filled at atmospheric pressure.

Abstract: A manual servo control valve for variable displacement axial piston pump incorporating a blocking mechanism which serves to block the inlet and outlet ports of the valve when the valve is not operating to change the displacement of the pump.

Abstract: A control for a variable displacement pump in which a displacement control element is made responsive to a load sensing valve and a pilot pressure relief valve. A control fluid is supplied to the pressure relief valve and the load sensing valve and the control pressure fluid controls the working pressure fluid which operates the stroking piston for the pump.

Abstract: A pressure compensated pump which supplies fluid to a common header has an automatic pressure compensator adjustment mechanism which adjusts the pressure setting of the pressure compensator in response to changes in the displacement of the pump, such that the compensator pressure setting of the pump is reduced when the displacement of the pump increases to increase pump flow and the pressure setting is increased when the displacement of the pump decreases to reduce pump flow.

Abstract: A control for a variable displacement pressure compensated pump in which pressurized control fluid regulates the setting of a sequence valve to set the maximum output pressure of the pump and also set the displacement of the pump. The sequence valve is a two-stage device which utilizes a sequence poppet stage and cone stage. When working fluid pressure exceeds the setting of the sequence valve, the cone stage spills to reduce the displacement of the pump. If the pressure is not reduced fast enough the sequence poppet spills to more rapidly reduce the displacement of the pump.

Abstract: The instant invention relates to an electrically operated control which operates the displacement setting mechanism of a variable displacement pump and allows the displacement mechanism to be manually operated when the electrically operated control is disabled.

Abstract: A horsepower limiter control for an axial piston pump provides a simple adjustment for setting the maximum horsepower the pump can provide and automatically adjusts the product of working pressure and maximum pump displacement to maintain the set horsepower. The horsepower limiter control operates to reduce the displacement of the pump when working fluid pressure exceeds the setting of the sequence valve.

Abstract: A variable displacement axial piston pump has a rocker cam for controlling the output of the pump. The rocker cam is driven by a fluid motor member. A valve with a follow-up device regulates pressure fluid flow to the fluid motor member to move the rocker cam. Both the fluid motor member and a part of the follow-up device are rigidly secured to and movable with the rocker cam to provide precise positioning of the rocker cam.

Abstract: In a hydraulic system having a plurality of variable displacement pumps driven by a prime mover, each pump has a variable ratio input device connected to a load sensing means. Each variable ratio input device automatically reduces the displacement of its respective pump by the same proportion when the prime mover is overloaded irrespective of the displacement setting of the pump and automatically increases the displacement of its pump by the same proportion up to the set displacement when the prime mover is not overloaded.

Abstract: A variable displacement axial piston pump has a rocker cam for controlling the output of the pump. The rocker cam is driven by a fluid motor member. A valve with a follow-up device regulates pressure fluid flow to the fluid motor member to move the rocker cam. Both the fluid motor member and a part of the follow-up device are rigidly secured to and movable with the rocker cam to provide precise positioning of the rocker cam.

Abstract: A low friction seal assembly for a fluid energy translating device seals a pair of pressure fluid chambers from one another. The assembly is mounted in a movable member of the device and has an elastic member which mechanically and hydraulically biases a seal member into engagement with the walls of the device.