Hydraulic control system for working machine

摘要

A hydraulic control system for a working machine according to the present invention includes a regulator control valve for controlling an operation of a pump regulator and a controller for sending a control signal for changing a discharge quantity of the pump to the regulator control valve in accordance with an operation amount of an operating device. This system further includes a fail-safe valve disposed in a control line joining the pump regulator and the regulator control valve. The fail-safe valve is configured so as to switch from an ordinary position to a fail-safe position in accordance with a failure signal indicative of failure in the regulator control valve.