| 摘要 |
<p>1,197,483. Valves. CATERPILLAR TRACTOR CO. 29 Sept., 1967 [21 Oct., 1966], No. 44369/67. Heading F2V. [Also in Division E1] An overridable check valve mechanism 12 in combination with a fluid driven motor M, e.g. driving the elevator of a self-loading earth scraper, which may be subjected to an external reversing force that can be blocked when it is below a predetermined magnitude, comprises a first check valve 34 defining a first unidirectional flow passage from a pump P to the motor, a second check valve 46 defining an oppositely directed unidirectional flow passage from the motor, and biasing means, e.g. a spring 53, holding the second valve closed when the reversing pressure at the motor is below the predetermined magnitude. Check valve 34 is formed by a piston 36 having flow passages 43, and loaded by a spring 39 on to a step 33. Valve 46 is carried by the valve 34, and comprises a ball closure 52. A relief valve 56 connects the system with a reservoir 17, and is set to open at a higher pressure than valve 46. An isolating valve 22 controls flow from the pump P directly back to a reservoir 17.</p> |
