| 摘要 |
A lift valve or tap is actuated by a non-rising spindle (12). The spindle (12) comprises a sleeve (20) and a shaft (22) coaxially mounted in the sleeve (20). The lower portion of the shaft (22) is threaded (23) and engages a closing member (18). Upon rotation of the spindle (12) the closing member (18) opens or closes the valve. Closing member (18) carries a seal (19) cooperating with a valve seat (42). To prevent excessive torque on the closing member (18) in the fully open and fully closed position of the valve, a torque-limiting device (24, 26, 28) is arranged between the lower end of the sleeve (20) and the threaded part (23) of the shaft (22). The torque-limiting device comprises a compressible washer (26), a first corrugated disk (24) and a second corrugated disk (28). The compressible washer (26) is positioned between the base of the shaft (22) and the upper corrugated disk (24). The lower corrugated disk (28) is located on the shaft (22) and cooperates with the upper corrugated disk (24). If the torque applied to the sleeve (20) via handle (40) reaches a predefined level, first (24) and second (28) corrugated disks rotate relative to one another similar to a ratchet-type clutch and an excessive torque on the closing member (18), seal (19) and valve seat (42) is prevented. As a second means for limiting torque, the closing member (18) is shaped to rotate within the valve housing (14) when subjected to a predefined rotational torque. For this purpose the bore of the housing (14) is of non-circular cross-section allowing slip between housing (14) and closing member (18) above a predefined torque. Preferably the shaft (22), the closing member (18) and the housing (14) are made of plastic, for example ABS, PVC or polypropylene. |
