Patent ID: 7047734

Claim:
A hydraulic circuit for a hydraulic cylinder, wherein the hydraulic cylinder comprises a first cylinder chamber to which an operating oil is supplied during a retracting operation; a second cylinder chamber to which an operating oil is supplied during an extending operation; an accumulator comprising an accumulator piston which is inserted into a cylinder rod and divides an interior of the cylinder rod into first and second cylinder rod chambers, and a gas which is hermetically charged into the second cylinder rod chamber; and an accumulation port which supplies and discharges an operating oil to and from the first cylinder rod chamber of the accumulator, the hydraulic circuit comprising a damping control valve having: a first switching position in which connection of the accumulation port with outside is blocked, and supply and discharge or discharge and supply of the operating oil are performed for the first cylinder chamber and the second cylinder chamber, a second switching position in which at least the accumulation port and the second cylinder chamber are connected, and a third switching position in which at least the accumulation port and the first cylinder chamber are connected.