| 摘要 |
PCT No. PCT/GB93/01791 Sec. 371 Date May 18, 1994 Sec. 102(e) Date May 18, 1994 PCT Filed Aug. 23, 1993 PCT Pub. No. WO94/07061 PCT Pub. Date Mar. 31, 1994.The bearing of a machine tool spindle is sealed by a pair of wiping seals mounted on the shaft and resiliently urged into contact with opposite faces of a stationary ring through which the shaft extends. The very small clearance between the ring and the shaft is fed with gas for example air at low pressure. When there is no gas supply and for example when the shaft is stationary the seals contact the ring and the resilience ensures good contact and prevents seepage of for example lubricant along the shaft from one side of the seals to the other. When the shaft is to be driven, low pressure gas is supplied and this pressure deflects the seals to lift them from the face of the ring so that there is no frictional engagement and either power loss or heat generation, and any liquid which does go past the seals is thrown outwardly by centrifugal force and driven by the escaping gas. |
