| 摘要 |
PROBLEM TO BE SOLVED: To provide a revolution controlling method capable of performing an emergency stop at the time of revolution by boosting relief set pressure of a relief valve only when an operating lever for revolution is operated in the direction that an upper revolving body is revolved in the other direction. SOLUTION: When a revolution stop is performed, a reverse lever operation is performed. In the case, a command signal is outputted to a solenoid 40 of an electromagnetic switch valve 39 based on each of a revolving motor rotation detection signal and a lever angle detection signal from potentiometers 41, 42 in a controller 43. Because the solenoid 40 is energized, the electromagnetic switch valve 39 is switched from a cutoff oil path locating G to an opening oil path location H. Pilot pressure from a pilot pressure source 38 acts on each of pressure intensifying operating parts 36, 37 via a pipeline 44, the H location of the electromagnetic switch valve 39 and a pipeline 45. Therefore, relief set pressure of the relief valves 34, 35 is boosted, sudden braking force works on a revolving motor 3 and sudden stop of revolution in an emergency can be performed. |
