| 摘要 |
A fluid pump dispenser has a pump body including a pump cylinder defining a pump chamber with a valve controlled product inlet passage leading to the chamber, a manually reciprocable pump plunger having a hollow stem defining a discharge passage leading from the chamber, a pump piston mounted on the inner end of the stem for relative sliding movement, the body having a plunger return spring for biasing the plunger into a raised position, the piston being limited for relative sliding movement between discharge open and closed positions, the piston having an annular projection defining a discharge valve seated in an annular groove of a plug element fixedly mounted to the stem at its inner end. A lost-motion effect is created between the piston and the stem which closes the discharge valve during the pressure stroke and opens the discharge during the intake stroke. The plunger is capable of being locked in up and down positions, an outer surface of the plug element sealing the inlet passage closed in the plunger lock-down position.
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