| 摘要 |
<p>PROBLEM TO BE SOLVED: To obtain a smooth starting characteristic irrespective of intensity of inertial moment, and secure satisfactory operability without reducing torque of an inertial body, in a pressure control valve which is arranged on a hydraulic motor circuit for rotationally driving the inertial body provided with a working machine whose inertial moment is varied according to an attitude. SOLUTION: A first control piston mechanism 37 is prepared by slidably fitting a first hollow control piston 51 integrated with a spring receiving part 36 and having a first control chamber 52 thereinside to the inside of a sleeve 50. Assembled in the first control piston mechanism 37 in series is a second control piston mechanism 69, which is composed of a first piston part 71 housed in a hollow portion of the first control piston, a flange part 72 abuttable against an end of the first control piston, and a second piston part 73 on the opposite side to the first piston part. Outside control pressure is introduced into the second control chamber 74 of the second piston part.</p> |
