Patent ID: 7730705

Claim:
A mower deck lift mechanism for a lawn mower having a frame, the mower deck lift mechanism comprising: a mower deck; a linkage mechanism for movably mounting the mower deck to the frame for raising and lowering movement relative to the frame; and an electro-hydraulic actuator assembly connected to the linkage mechanism for raising and lowering the mower deck relative to the frame, the actuator assembly including a hydraulic piston-cylinder assembly connected to the linkage mechanism, a pump for supplying pressurized fluid to the piston-cylinder assembly, and an electric motor for driving the pump; and wherein the actuator assembly includes valving that supplies pressurized fluid from the pump to the piston-cylinder assembly when the motor is energized, and returns fluid from the piston-cylinder assembly to a reservoir when the motor is not energized, whereby movement of the piston-cylinder assembly is not inhibited when the motor is not energized, wherein the valving includes a pilot operated check valve assembly including an inlet connected to the outlet of the pump, an outlet connected to a working chamber in the piston-cylinder assembly, a return connected to a reservoir, a pilot valve movable from a first position by fluid pressure at the inlet to a second position connecting the inlet to the outlet for flow of pressurized fluid to the working chamber of the piston-cylinder assembly, and the pilot valve in the first position connecting the working chamber of the piston-cylinder assembly to the return for allowing flow of fluid from the working chamber to the reservoir.