| 摘要 |
The hand-operated pump has a piston which is reciprocated within the hollow pump body by a plunger which itself is reciprocated through an opening in a collar at one end of the pump body. When the plunger is in a fully extended condition at one end of a stroke, a direct seal is obtained between an annular projection on the plunger and an annular groove on the collar which receives said projection. Thus, leakage is prevented along the interface between the plunger and the collar through the opening during shipment or accidental inversion of the pump at other times.
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