Patent ID: 7704283

Claim:
A prosthetic leg which is configured to be attached to a leg that has been amputated proximal to the knee as a substitute leg, and which is installed with a hydraulic cylinder for adjusting bending and extension resistance of a knee joint portion, wherein, when a piston provided in a cylinder chamber of the hydraulic cylinder moves in a direction for extending the prosthetic leg, an extension passage allows passage of a liquid in a first cylinder chamber into a second cylinder chamber, and when the piston provided in the cylinder chamber of the hydraulic cylinder moves in a direction for bending the prosthetic leg, a bending passage allows passage of the liquid in the second cylinder chamber into the first cylinder chamber, the bending passage bifurcates into two at a midway point thereon so as to connect to the first cylinder chamber side, a toe grounding closing valve being provided at a midway point on the bending passage prior to bifurcation for closing the bending passage when a toe on a foot portion of the prosthetic leg contacts the ground and a heel grounding closing valve being provided at a midway point on one of the bending passages following bifurcation for closing the bending passage when a heel on the foot portion of the prosthetic leg contacts the ground, and the toe grounding closing valve and the heel grounding closing valve are connected by a closing valve connecting/operating member for connecting the toe grounding closing valve and the heel grounding closing valve in an interlocking manner such that valve open/close orientations thereof are set in opposite directions.