HYDRAULIC CONTROL DEVICE AND CONSTRUCTION MACHINE WITH SAME

摘要

A hydraulic control device (10) is provided with: a hydraulic pump (30) to which steering cylinders (18L 18R) and boom cylinders (22) are connected in parallel; a steering control valve (34) which controls the direction of hydraulic oil flowing to the steering cylinders (18L 18R); and a boom control valve (44) which when set to a neutral position connects the hydraulic pump (30) to a tank (48) and which when set to an offset position controls the direction of hydraulic oil flowing to the boom cylinders (22). The hydraulic control device (10) is also provided with: a meter in compensator (33) which according to pressures across the variable throttle (37) of the steering control valve (34) increases the rate of flow which is caused to flow to the steering control valve (34); and a bleed off compensator (42) which in response to an increase in the pressure of hydraulic oil caused to flow to the steering cylinders (18L 18R) reduces the rate of flow caused to flow to the boom control valve (44) and maintains hydraulic pressure in the steering control circuit (31) at a predetermined pressure.