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 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: 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 flow control valve for use in a hydraulic system including a variable orifice for creating a pressure drop to control the rate of fluid flow to a fluid pressure operated device. A pressure compensating device incorporated in the valve is responsive to deviations in pressure drop across the orifice to modulate the flow thereto and thereby maintain a preselected pressure drop across the orifice. Opening of the variable orifice is by inlet pressure against the force of a light spring to an adjustable stop. Retarding opening of the orifice is an expansible chamber having variable volume and connected through an adjustable flow restriction valve to the control valve outlet. Adjustment of the flow restriction valve controls the rate of opening of the variable orifice to reduce pressure shock to the hydraulic system upon initiation of flow.