US Patent 10226826 Hydraulic power tool

A hydraulic power tool includes a housing defining a cylinder, a piston at least partially positioned within the cylinder and movable between a retracted position and an extended position, a reservoir containing hydraulic fluid, a pump for transferring hydraulic fluid in the reservoir to the cylinder, causing the piston to move from the retracted position toward the extended position, a return valve defining a rotational axis and positioned between the cylinder and the reservoir, and a valve actuator driven by the pump for opening the return valve, thereby fluidly communicating the cylinder and the reservoir, in response to a predetermined pressure being reached in the cylinder.