| 摘要 |
PURPOSE:To eliminate the effects on running during the operations of boom and arm by a method in which the first running switch valve is connected to the first oil-pressure pump by a bypass with a throttle and also connected to the second oil-pressure pump through an interlocking switch valve. CONSTITUTION:When opening a boom switching valve 26, most of pressure oil is sent to a boom cylinder 50 through the valve 26 to drive a boom because the valve 32 is present downstream of the valve 26 and a throttle 100 is present in a bypass 98 connecting the first pump 4 with the valve 32. Also, the pressure oil of the second pump 6 passes through the second running switch valve 38 in the uppermost stream side to drive the motor 58, and at the same time the switch valve 64 is opened in an interlocking manner with the operation of the valve 26 and the pressure oil of the pump 6 is sent to the valve 32 through the bypass 104 to drive the motor 56. By this, even when the valve 26 is opened during the running period, all of pressure oil from the pump 4 is not cut by the valve 26, large change in running speed does not occur, and the lowering of the speed is made less. |
