Patent attributes
In a hydraulic driving system for construction machines, when track motors 3f and 3g are operated and the delivery pressure of a main pump 2 increases to a second value PS2 of the set pressure of a main relief valve 14, the set pressure of a signal pressure relief valve 16 increases from a third value PA1 to a fourth value PA2, which is smaller than the second value PS2 of the set pressure of the main relief valve 14, the difference between the second value PS2 and the fourth value PA2 being smaller than the target LS differential pressure. With such a structure, even if one of actuators reaches the stroke end and the delivery pressure of the hydraulic pump rises to the set pressure of the main relief valve, the other actuators do not stop, and further when the main relief valve is configured to increase the set pressure during operation of a specific actuator, the load pressure of the specific actuator does not increase to the increased set pressure of the main relief valve.
