CHARLES PETER HEISIG
Engineers in Groffdale, PA

5359836, Nov 1, 1994

Feb 1, 1993

8/012000

Kenneth W. Zeuner - New Hope PA
Thomas A. Chmielewski - Langhorne PA
Mark K. Torbett - Langhorne PA
Carl E. Bohman - New Holland PA
Charles P. Heisig - New Holland PA

Control Concepts, Inc. - Newtown PA

A01D 7528

56 102E

A method and apparatus for controlling an agricultural harvester having a cut crop receiving header coupled to a hydraulic cylinder. The header applies a force against the ground that is adjusted by applying pressure to the cylinder. A first proportional valve is fluidly coupled to the cylinder, and responds to a first input signal by increasing pressure in the cylinder to a setpoint value, when the pressure is less than the setpoint. A second proportional valve is also fluidly coupled to the cylinder, and responds to a second input signal by reducing pressure in the cylinder to the setpoint pressure value, when the pressure is greater than the setpoint. A pressure signal representing cylinder pressure is received. The difference between the measured pressure and the setpoint is used to compute the first and second input signals, which are transmitted to the valves. Cylinder pressure is maintained substantially at the setpoint, maintaining the force applied against the ground by the header substantially constant.

6606858, Aug 19, 2003

Nov 28, 2001

09/996303

Jeffrey C. Hansell - Overbrook KS
Richard J. Barrett - Ames IA
Charles P. Heisig - New Holland PA
Nianzhu Luo - Easley SC

Sauer-Danfoss Inc. - Ames IA

F16D 3102

60444, 60468

The neutral override circuit of this invention includes a variable displacement pump controlled by a servo fluidly connected to a displacement control that is biased to a neutral position. A charge pump is connected to the pump and the displacement control. A solenoid-operated neutral override brake control valve is connected to the charge circuit upstream of the displacement control valve and is normally biased to an open position. However, the solenoid urges the valve to a closed position in a response to a signal indicating that the brake has been released. In the open position, the valve dumps charge flow to the pump case until the supply pressure to the displacement control is inadequate to overcome the centering bias of the displacement control. The characteristics of the brake control valve can be set so that some minimum charge pressure and lubricating flow are still provided to the rotating elements of the pump.

5351601, Oct 4, 1994

May 4, 1992

7/878349

Kenneth W. Zeuner - New Hope PA
Charles Heisig - New Holland PA

Control Concepts, Inc. - Newtown PA

F15B 1108, F16D 3102

91445

A hydraulic control system in which the flow of hydraulic fluid to and from cylinders on either side of a piston is controlled by normally closed check valves that are opened whenever a control valve is not in its neutral state. Float check valves respectively in series with the check valves and the check valves are opened when the control valve is in a neutral state by pressure from one of the cylinders so as to permit the load to move freely in response to external forces applied to it. A normally closed check valve is provided in which load sense pressures drive it open and pressure from a cylinder is balanced out. A cross check valve is such that the ratio of the areas for driving it open to the area for keeping it shut are at least 35:1.