| 摘要 |
PURPOSE:To prevent the shock when an upper rotary body is stopped by reversely controlling a variable pump to stop the upper rotary body when a construction machine turns and descends at a crawling speed and is stopped on a slope. CONSTITUTION:The oil pressure discharged from a variable pump 1 is fed to an actuator 6 from a pipeline 2 or 3 via a pilot check valve 4 or 5 to rotate the upper rotary body of a construction machine, and pressure detectors 14, 15 detecting the pressure of individual pipelines 2, 3 and a potentiometer 13 detecting the operation angle of an operation lever 7 are provided to feed these output signals to a control circuit 8. When the upper rotary body is to be stopped while a vehicle turns and descends at a crawling speed on a slope, if the pressure difference between the suction and discharge sides of the variable pump 1 is a preset value or more, the variable pump 1 is reversed immediately before the upper rotary body is stopped, and the inclination angle of a slant plate 1a is controlled so that the oil pressure is temporarily discharged to the suction side. |
