| 摘要 |
<p>PURPOSE:To prevent an external force loss by a method wherein a hydraulic pressure is recirculated and functioned to a rear end part of a hydraulic pressure generating piston in a master cylinder, in the master cylinder suitable for a negative brake device for industrial machineries. CONSTITUTION:The first and second oil chambers 6, 7 are connected to each other through a recirculation check valve 9 interposed in an axial flow path 8 of an axial part of a piston and checking the recirculation from the second oil chamber 7 to the first oil chamber 6. When an external force is applied to a push-rod 11, the first check valve 14 closes the flow path while the second check valve 18 closes the flow path by cooperating with a rod 12. Accordingly, an oil pressure is generated in the oil chamber 6 by an advance of the piston 4 after the closure of the flow path. The oil is also flowed into the oil chamber 7 from a reservoir or the oil chamber 6 by the first and second check valves 14, 18. In this case, a resilient force of a spring 15 of the first check valve 14 is so designed as to be bigger than that of a spring 19 of the second check valve 18. Accordingly, the oil is flowed into the oil chamber 7 from the reservoir due to a negative pressure condition of the chamber 7 at an initial period of braking, thereafter, the oil pressure is delivered from the oil chamber 6 to the oil chamber 7 through the first check valve 14.</p> |
