| 摘要 |
1,204,287. Valves. ALLIS-CHALMERS MFG. CO. 10 June, 1969 [19 June, 19681, No. 29266/69. Heading F2V. A rotary valve is characterized in that a pair of seal elements 33, 34, arranged on either a valve body or on a member 7, is constructed for alternate selective engagement with a corresponding seal means so that the non-engaged element may be replaced when worn. The spherical valve member 7 carries the two seal elements 33, 34 at right angles to the plane of the through bore 32. On rotation to a closed position effected by hydraulic cylinder 52, one or other of the seal elements is hydraulically actuated via pipes 47, 48 or 49, 51. Assuming the upstream seal is actuated, the downstream seal may be replaced. Thereafter the valve is opened and a pin 59 inserted to hold it open whilst the piston-rod 53 is uncoupled from an arm 56 and coupled to an arm 58. The valve is then closed, bringing the new seal element upstream. If this seal is actuated, the old seal element, now downstream, may be replaced. |
