| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a hydraulic control circuit for construction machinery capable of distributing pump horsepower into a boom cylinder and a turning motor through lifting and turning action in the optimum manner. <P>SOLUTION: This hydraulic control circuit for construction machinery is constituted in such a way that regulators are arranged in a first pump and a second pump of twin variable displacement hydraulic pumps, respectively, each regulator is controlled by a controller to detect discharge pressure of each pump and absorb torque remaining after absorbing by the pump on one side by the other pump, pressure oil from the first and second pumps is joined and supplied into the boom cylinder in boom lifting operation, and pressure oil from the second pump is supplied into the turning motor in turning operation. Flow rate distribution control parts 13b, 13c controlling the regulators 23, 24 are provided to provide difference in flow rate between both pumps to increase discharge flow rate of the first pump by fixed amount when starting composite operation of boom lifting and turning and reduce difference in flow rate when difference in pressure is increased between the first and second pumps when turning operation becomes steady. <P>COPYRIGHT: (C)2005,JPO&NCIPI</p> |
