Patent ID: 8356985

Claim:
A fluid system, comprising: an over-center fluid operated motor having a first motor port for high-pressure fluid supply and a second motor port for low-pressure fluid supply; and an actuation system, including first and second fluid control ports, coupled to the motor and configured to control changes in displacement of the motor, the actuation system being arranged to change the displacement of the motor in a first direction relative to a zero displacement position, up to a maximum displacement angle, when a high fluid pressure is present at the first control port, and to change the displacement of the motor in a second direction relative to the zero displacement position, up to a maximum displacement angle, when a low fluid pressure is present at the first control port, the actuation system being further configured to change the displacement of the motor to the zero displacement position when an equal fluid pressure is present at each of the first and second fluid control ports; and a control valve having first and second output ports in fluid communication with the first and second fluid control ports, respectively, the control valve configured to close the first and second output ports while in a first valve position; to place, while in a second valve position, the first output port in fluid communication with a high-pressure fluid source and the second output port in fluid communication with a low-pressure fluid source; to place, while in a third valve position, the first output port in fluid communication with the low-pressure fluid source and the second output port in fluid communication with the high-pressure fluid source; and to place, while in a fourth valve position, the first and second output ports in fluid communication with the high-pressure fluid source.