| 摘要 |
<p>1,008,324. Valves. NEW YORK AIR BRAKE CO. Aug. 6, 1964 [Nov. 26, 1963], No. 31990/64. Heading F2V. A three-position control valve 11 for a double-acting motor 12, for raising and lowering the bucket-carrying boom 13 of a loader, has inlet and exhaust ports 14 and 16 which are connected to a reservoir 17 and a bore encircled by seven annular chambers 21-27. Chambers 23 and 25 are connected to the inlet port 14 via passage 28 in which is a relief valve 32, chambers 21, 24 and 27 are connected to the exhaust port via manifold 29 and chambers 22 and 26 are connected with the motor ports. Chamber 22 has a longitudinal extension 31. A hollow valve closure member 33 has two annular grooves 34 and 35 with three lands 36-38; and two axial bores 39 and 41 extend into the member 33 from either end, whilst radial bores 44, 45 and 47, 48 extend from each bore, each bore also containing a check valve 46, 49. Plugs 42, 43, close the outer ends of the bores. The end faces of lands 36, 38 contain conical undercuts 51, 52, intersected by radial passages 53, 54, whilst a check valve 50 seats on the end of 1 and 36 and encircles the member 33. In the neutral position of the plunger, 1 and 36 and 38 isolate chambers 22, 26, and so hydraulically lock the motor, and fluid from pump 15 passes through passage 28, chambers 23, 25, grooves 34, 35, chamber 24 and manifold 29 to reservoir 17. To raise the boom 13, the member 33 is moved to the right to interrupt communication between ports 14, 16, and connect passages 44, 45, 48 and 47, with chambers 22, 23, 26 and 27 and passage 53 with chamber 24. Port 22 is connected to the pump 15 by means of passage 28, annular chamber 23, radial passages 45, bore 39, check valve 46, radial passages 44. Fluid then passes along conduit 18 to the rod end of the motor whilst fluid from the head end is discharged by conduit 19 to the reservoir 17. The boom 13 is locked into position by moving the member 33 into its neutral position. To lower the boom 13 the member 33 is moved to the left and the head end of the motor is connected to the pump 15 similarly to before, whilst the rod end discharges fluid to the supply passage 28 and through check valve 50 to the reservoir 17. When the boom has passed through its vertical position in any one movement, the pressure required to continue this movement lessens, but stability of the fluid is maintained by the check valve which is kept shut by its spring on raising the boom and is opened to release discharged fluid to the reservoir 17 on lowering the boom. To prevent cavitation, a second valve 55 and extension 31 may be fitted adjacent the undercut 52 and the groove 26 respectively. Specification 812,490 is referred to.</p> |
