Patent ID: 6415604
Filing Date: 2002-07-09
Classification: E02F

Abstract:
A hydraulic control circuit for a work machine with a plurality of hydraulic actuators for actuating a working portion, control valves that control the feeding of pressurized oil to the respective hydraulic actuators, a control unit, and a valve drive means to actuate the control valves on the basis of control commands from the control unit, the control circuit comprising:a means for judging whether the working portion has reached an interference preventing area predetermined with respect to an operator's cab and a limit position set so as to prevent the working portion from being brought into contact with obstacles other than the operator's cab, on the basis of input signals from a position detecting means to detect the position of the working portion; an interference prevention controlling means that, when it is judged by the judging means that the working portion has reached the interference preventing area, outputs to a valve driving means control commands to one of stop the hydraulic actuators and to actuate the hydraulic actuators in the direction by which the working portion moves away from the work machine based on the position of the working portion; and a position limitation controlling means that outputs control commands to stop the hydraulic actuators to the valve driving means when it is judged by the judging means that the working portion has reached the limit position, wherein the valve driving means comprises an interference prevention electromagnetic valve that is changed so as to feed pilot pressurized oil to actuate a first hydraulic actuator of the plurality of hydraulic actuators to a pilot oil line to actuate a second hydraulic actuator in a direction away from the interference prevention area and a stop electromagnetic valve to stop the operations of said hydraulic actuators.