HYDRAULIC DRIVING DEVICE FOR CONSTRUCTION MACHINE

摘要

PROBLEM TO BE SOLVED: To provide a hydraulic driving device for a construction machine with a high safety capable of avoiding unexpected reduction in driving torque or braking torque of a revolving hydraulic motor even when any failure occurs in a constituent component.SOLUTION: A hydraulic driving device for a construction machine comprises: a first revolution relief valve which limits a driving pressure or a braking pressure of a revolving hydraulic motor equal to or lower than a first preset pressure; a second revolution relief which can be switched by a pilot pressure oil supplied to an operating section of the second revolution relief valve in such a manner that the driving pressure or the braking pressure of the revolving hydraulic motor is limited equal to or lower than a second preset pressure lower than the first preset pressure; a switching valve for communicating/cutting off the revolving hydraulic motor and the second revolving relief valve with a pilot pressure oil supplied to an operating section of the switching valve; a solenoid valve which generates the pilot pressure oil to be supplied to the operating section of the switching valve and the operating section of the second revolution relief valve; and a control unit which outputs an operation signal for driving the solenoid valve.