Abstract: A hydraulically operated device including a single-acting cylinder having a piston for operating a working tool, a pressure chamber for applying a hydraulic pressure to the piston from an original position to an operated position, and a return spring for biasing the piston toward the original position. The device includes a hydraulic pump for delivering a pressurized fluid to be fed into the pressure chamber of the cylinder, and an automatic drain valve for inhibiting the pressurized fluid from being discharged from the pressure chamber while a difference by which a delivery pressure of the pump is higher than a pressure in the pressure chamber exceeds a predetermined value. When the difference becomes smaller than the predetermined value, the automatic drain valve is operated to allow the pressurized fluid to be discharged from the pressure chamber. Thus, the automatic drain valve automatically drains the pressure chamber when the pump is turned off.

Abstract: A hydraulically operated device including a single-acting cylinder having a piston for operating a working tool, a pressure chamber for applying a hydraulic pressure to the piston from an original position to an operated position, and a return spring for biasing the piston toward the original position. The device includes a hydraulic pump for delivering a pressurized fluid to be fed into the pressure chamber of the cylinder, and an automatic drain valve for inhibiting the pressurized fluid from being discharged from the pressure chamber while a difference by which a delivery pressure of the pump is higher than a pressure in the pressure chamber exceeds a predetermined value. When the difference becomes smaller than the predetermined value, the automatic drain valve is operated to allow the pressurized fluid to be discharged from the pressure chamber. Thus, the automatic drain valve automatically drains the pressure chamber when the pump is turned off.

Abstract: A pipe cutting device comprises a housing to which a tool case is attached to be rotatable, and by rotating manually or electrically the tool case so that the openings of the tool case and a follow-up gear disposed in the tool case substantially align with the opening provided for the housing, is formed a pipe inserting passage for inserting a pipe from the opening side of the openings of these members towards the central portion of the tool case. Two driving gears meshed with the follow-up gear are driven by a motor through the power transmission mechanism to rotate the tool case. The rotation of the tool case drives the cam roller to operate the cam plate, and the clutch arm is rotated by predetermined angles by every one rotation of the tool case thereby to minutely rotate the eccentric cam by predetermined angles through the one-way clutch. The rotation of the eccentric cam rotates the lever mechanism which is operatively connected to the cutter.