| 摘要 |
A hand pump includes a piston slidably engaged in a housing for separating the housing into two chambers. A tube is secured on top of the housing. The piston includes two annular grooves for receiving two sealing rings. A piston rod has one end secured to the piston and has the other end extended outward of the housing. The piston may pump the air in upper chamber into the tube when the piston moves upward, and the air in the lower chamber may be pumped into the tube when the piston moves downward. The tube includes two mouths for engaging with different tire valves.
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