| 摘要 |
PURPOSE:To sense a variation in revolution of a pump and a cargo handling operation so as to timely control the capacity of a hydraulic device by setting the flow rate of hydraulic oil after being restricted by a flow control valve which is pilot-controlled by a pressure from a cargo handling circuit, to a value which is higher than a required flow rate of a power steering circuit. CONSTITUTION:With no cargo handling operation, the flow rate of hydraulic oil flowing through a discharge pipe line 12 is limited at the outlet side of a flow control valve 20 under the action of a notch 24a, and simultaneously, a differential pressure is produced between an inlet pressure P1 and an outlet pressure P2. Further, at this time, the outlet side flow rate is set to a value which is slightly higher than a required flow rate of a power steering circuit 13 which is ensured by a flow divider 14, and accordingly, the feed of extra hydraulic oil into a cargo handling circuit 15 is limited to a very slight value. When the flow rate of hydraulic oil flowing through the pipe line 12 due to an increase in the rotational speed of an engine 10, the pressures P1, P2 and the outlet side flow rate increase. An increase in the pressure P1 affects the pressure of a hydraulic chamber in a control cylinder 14 just after being transmitted through a volume control valve 30 which is held in an equilibrium condition by a differential pressure from the pilot pipe line 28, and accordingly, a piston rod 42 moves overcoming the urging force of a return spring 11a so as to change the inclining angle of a swash plate in a decreasing direction. |
