| 摘要 |
PURPOSE:To furnish an unload valve which maintain a constant descending speed of a table gate and the like of a car with an additional function of a flow rate regulator valve, by providing said valve with a backpressure chamber which contributes to actuates a backpressure to close a return passage of oil pressure. CONSTITUTION:A backpressure chamber 32 communicating with a return passage 8 is made in a valve main body 2. When descending speed of a piston of a cylinder 28, that is, speed of returning flow of pressure oil is increasing due to a big force 30 working on a table gate, the pressure in the backpressure chamber 32 grows high and pushes up a valve spool 10 against tension of a spring 20, working so as to close the return passage 8 by means of an extended head 12. When the return passage 8 is closed, the pressure in the backpressure chamber 32 is lowered and the valve spool is again pushed down by the returning pressure oil to open the return passage 8. Thus, quantity of flow through the return passage 8 is always maintained constant regardless of the magnitude of external load 30. |
