| 摘要 |
A liquid dispensing pump for a portable container in which the pump piston is disposed for lost motion in the pump cylinder between the plunger rod and a discharge valve carried by a stem affixed to the plunger rod and extending through the piston. The piston has upwardly and downwardly presented elastomeric skirts of which the lower skirt seats against the discharge valve on the piston upstroke and the upper skirt seats against a venting valve at the termination of the upstroke. Both the discharge valve and the venting valve exert an expanding action on the respective piston skirts incident to their seating relation with the skirts under the resilient pressure of the pump spring, to counteract any shrinking tendency of the skirts, and means are provided for limiting the expansion of the skirts. The upper and lower ends of the piston are symmetrically arranged to permit reversal of its position in the pump.
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