| 摘要 |
When the plunger is fully depressed, radially projecting lugs carried by the plunger adjacent its normally upper end may be received within corresponding notches in a collar through which the plunger reciprocates, whereupon rotation of the plunger in a clockwise direction moves the lugs under overhanging shoulders of the collar so as to prevent extension of the plunger until it is intentionally unlocked from the collar. A total of three lugs are utilized so as to provide three-point, stabilized retention of the plunger in its locked-down condition, and one of the lugs and its corresponding notch is smaller than the other two so that the plunger can be locked only when it is in a certain, predetermined rotative position relative to the collar aligning the down-sized lug and notch. Each of the shoulders is provided with a lower, lug-engaging, inclined surface which bears against its corresponding lug with progressively increasing force for fluid-tight sealing purposes as the plunger is rotated into a fully locked condition, there being abutments associated with the shoulders blocking movement of the lugs beyond positions corresponding to the fully locked and rotated position of the plunger.
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