Abstract: A power unit housing a pump, comprising: a hydraulic oil tank having an approximately L-shaped configuration and including a pump housing portion which houses a hydraulic pump and an oil reservoir portion which is integrally formed with and arranged approximately perpendicular to the pump housing portion; an electric motor juxtaposed alongside the oil reservoir portion, the electrical motor operating the hydraulic pump through a direct coupling; and a switching valve for switching the supply and discharge flow of the hydraulic oil between the hydraulic pump and an external load, the switching valve is positioned in proximity to the electric motor. According to this arrangement it is possible to shorten the axial length of the hydraulic oil tank while maintaining the volume of the tank and it is possible to make the entire unit compact.

Abstract: A hydraulic oil power unit includes a motor for driving a hydraulic pump, a piston driven by the hydraulic pump, a driving power supply for the motor and a switch for providing the driving power supply for the motor. A switching device includes a semiconductor for switching on and off a conductive path for the motor, a detecting circuit for detecting the completion of the motion of the piston from a motor current fed with the motor and a holding circuit for holding the switching device in a non-conductive state while the switch is closed based on a detection signal from the detecting circuit indicating a detection of the completion of the motion of the piston.