Patent ID: 7059124
Filing Date: 2006-06-13
Classification: E02F

Abstract:
1. A hydraulic control apparatus for work machines comprising: a blade that is attached to a vehicle main body so that the blade is capable of a tilting operation; first and second variable displacement hydraulic pumps; left and right tilting hydraulic cylinders that are attached to left and right of the blade, and that are driven by a supply of pressurized oil that is discharged from the first and second variable displacement hydraulic pumps; first and second main operating valves in which direction and flow rate of the pressurized oil that is supplied to the left and right tilting hydraulic cylinders are controlled; first and second discharge oil passages that connect discharge ports of the first and second variable displacement hydraulic pumps and the first and second main operating valves; first and second pressure compensating valves that compensate differential pressures before and after the first and second main operating valves to specified values; a first flow-combining/flow-dividing valve that switches between a flow-combining position that causes communication between the first discharge oil passage and second discharge oil passage, and a flow-dividing position that cuts off the communication between the first discharge oil passage and the second discharge oil passage; and control means for controlling the switching of the flow-combining/flow-dividing valve so that a switching action is performed in which the flow-combining/flow-dividing valve is switched from the flow-combining position to the flow-dividing position in cases where it is judged that a dual tilting operation is to be performed in which pressurized oil is supplied to a bottom end oil chamber of one of the tilting hydraulic cylinders among the left and right tilting hydraulic cylinders, and pressurized oil is supplied to a head end oil chamber of the other tilting hydraulic cylinder.