Abstract: A control device for a hydrostatic transmission including apparatus for sensing a speed of a prime mover which powers a variable displacement pump of the hydrostatic transmission and for regulating the displacement of the variable displacement pump in accordance with the speed of the prime mover, is disclosed. The control device also includes apparatus for transmitting a mechanical feedback signal representative of the displacement of the variable displacement pump to the control device to maintain the variable displacement pump at a displacement proportional to the speed of the prime mover.

Abstract: A variable displacement pump has a displacement control cam operably connected to a displacement control cylinder within a pump housing and a pressure and flow sensitive compensating valve is connected to the pump housing for regulating output of the pump. The compensating valve is secured to the pump housing through a spacer block. A lever is disposed partly in the spacer block and partly in a housing of the compensating valve responsive to positioning of the pump cam through a mechanical connection for actuating a sleeve in the compensating valve to incorporate torque-limiting feedback regulation of the pump. An adjustment is operable from an outer surface of the spacer block to limit torsional operation of the lever about a pivot point.

Abstract: A variable delivery pump has a pump control mechanism in a housing secured thereto for governing directional flow of fluid through the pump, the pump being adapted to be connected through a closed loop to a motor. A pressure compensating valve is provided in the housing for governing pressure output of the pump, and a pump control cylinder is provided for positioning a flow control cam of the pump in accordance with flow of fluid through the direction control valve and the pressure compensating valve. A cam plate is coaxially connected to a directional control rotatable valve spool of the direction control valve, the cam plate having an outer periphery that is continuously radially variable from a maximum radial point to a minimum radial point for either direction of rotation of the cam from the maximum radial point as the control spool is rotated in either direction from a normal position. The cam plate actuates a cam follower, which in turn actuates a slideable sleeve in the pressure compensating valve.

Abstract: A fluid horsepower control system is adapted to operate a fluid load by output of a variable delivery pump having a control cylinder governed by a pressure compensated variable orifice connected in multiple with a load sense control valve for causing fluid flow to be inversely proportional to pump discharge pressure and maintaining constant drop across the orifice, without requiring mechanical feedback from the variable delivery pump to the load sense control valve.