Patent ID: 7234574

Claim:
In a hydraulic damper having a cylinder, a piston movable in a reciprocating manner within said cylinder, hydraulic chambers provided at the opposite sides of the piston, and an on-off control valve provided in a passage for connecting both the hydraulic chambers and being on-off controlled to change a damping coefficient, a damping coefficient switching-type hydraulic damper, characterized by providing a hydraulic drive means in a hydraulic circuit of the cylinder for switching a damping coefficient without external electrical power supply by utilizing a change of hydraulic pressure at the time when the direction of movement of the piston is changed, said hydraulic drive means being structured so that a first damping coefficient is attained with the on-off control valve maintaining a closed state at the time when a movement of the piston in one direction causes hydraulic pressure in one hydraulic chamber to increase, and a second damping coefficient is attained with the on-off control valve once opened at the time when the movement of the piston is turned in the opposite direction to cause said hydraulic pressure to decrease, and afterwards, is switched to the first damping coefficient with the on-off control valve closed again in response to increasing hydraulic pressure in the other hydraulic chamber.