OIL PRESSURE CONTROLLER FOR OIL-PRESSURE SHOVEL

摘要

PURPOSE:To control the revolving number of a prime mover by providing a maximum push-off capacity setter to control the maximum push-off capacity of a pump to make it smaller as the revolving number of the prime mover increases when an optimal revolving number for lighter loads is exceeded. CONSTITUTION:A variable capacity type oil-pressure pump 13 and a fixed capacity type oil-pressure pump 15 are connected to an engine 11. A motor 19 and an actuator 21 for excavation are connected through a control valve 17 to the pump 13. The pump 15 is connected through a throttle 23 to a discharge path and also through an electromagnetic valve 25 to a maximum tilting angle controller 27. When the revolving number N0 of the engine exceeds an optimal revolving number NE for lighter loads, the discharge amount of the pump 15 is controlled to be reduced continuously according to the revolving number by signals from a revolving number sensor 30. The revolving number of the prime mover can be reduced without lowering of discharge amount in light operations even when higher horsepower is set for heavy load operations.