Patent ID: 8074558

Claim:
An axial piston device, comprising: a body defining at least one bore and having a central axis; a pump piston disposed within the at least one bore to at least partially define a pumping chamber; a tiltable plate biased into engagement with the pump piston; and an actuator configured to selectively tilt the plate relative to the central axis of the body to thereby vary a displacement of the pump piston within the at least one bore, the actuator including: a control piston operatively connected to move the tiltable plate; a rotary motor; and a valve driven by the rotary motor to control fluid communication between the control piston and a source of pressurized fluid to move the control piston, wherein the valve includes a valve element having a first spiral groove in fluid communication with a first end of the control piston, and a second spiral groove in fluid communication with a second end of the control piston.