Sauer-danfoss Inc.

Mark A Peterson

Stanley W Crull

An axial piston hydraulic machine having a housing with a cylinder block with reciprocating pistons disposed therein. The reciprocating pistons are rotatably connected to a swashplate at a first end of the swashplate. At a second end of a swashplate support balls are received and engage the housing. The support balls are located radially from the plurality of reciprocating pistons such that the distance between the axis of rotation of an input shaft and a piston axis of the plurality of pistons is significantly less than the radial distance between the axis of rotation of the shaft and the center points of the support balls, and wherein the pivot axis passing through the center points of the support balls lies in or near the plane passing through the piston/slipper ball joints.

Ball supported swashplate for axial piston hydraulic machine

A three position servo system. The servo system has a servo housing that has first and second control ports disposed therein in a cavity in fluid communication with the first and second control ports. A servo piston having at least one pressure chamber disposed therein is then used to communicate the pressure within the first and second ports into the first end of the cavity. Thus, when pressure is applied below a threshold pressure to both ports a first position is achieved, when pressure is applied above the threshold pressure in only one port a second position is achieved, and when pressure is applied above the threshold pressure in both ports a third position is achieved. Therefore, the servo system provides three different operating positions.

Three position servo system to control the displacement of a hydraulic motor

A specific type of hydraulic fan drive system is provided for engine drive machines, such as on road and off road machines, such as buses, construction equipment, agricultural equipment, and so on. The hydraulic fan drive systems turn a cooling fan (,) which provides airflow to cool the engine on such machines. This system uses a proportional pressure reducing valve (,) (or combination of valves providing a pressure reducing function) between the pump (,) and the fan motor (,). This valve (,) or (combination of valves) controls the pressure drop across the fan motor (,) based on a control signal from an electronic controller (,). The valve allows as little or as much flow to pass as is required to maintain this pressure drop at the load (the fan motor (,)).

Hydraulic fan drive system having a non-dedicated flow source

A tandem fixed displacement pump circuit with torque control includes first and second pumps that draw fluid from a reservoir to supply respective load circuits, pressure relief valves for each of the load circuits, and a pilot operated sequence valve that monitors the pressure for each of the circuits and reduces the pressure of one of the circuits as the pressure in the other circuit rises. The sequence valve modulates to control the pressure in the secondary priority circuit so that a predetermined input torque value is not exceeded.

Growing community of inventors

Ames, IA, United States of America

Mark A Peterson