| 摘要 |
A manual air pump includes an outer cylinder having a first chamber and a head provided to the second end of the outer cylinder. The head includes an outlet passage communicated with the first chamber for supplying air to an object to be inflated. An inner cylinder is securely mounted in the first chamber of the outer cylinder and includes a first end secured in the second end of the outer cylinder and a second end, the inner cylinder defining a second chamber that is communicated with the outlet passage. A piston rod has a first end with a piston slidably received in the first chamber of the outer cylinder and a second end extended beyond the outer cylinder, the piston separating the first chamber into a first chamber section adjacent to the head and a second chamber section distal to the head, the piston rod defining a third chamber therein. A handle is secured to the second end of the piston rod to move therewith. A plug is securely mounted to the second end of the inner cylinder and in sliding contact with an inner periphery defining the third chamber of the piston rod, the plug separating the third chamber into a third chamber section distal to the handle and a fourth chamber section adjacent to the handle, the plug having a one-way valve mounted therein such that air is only flowable from the fourth chamber section into the second chamber. A first release valve is provided for optionally communicating the fourth chamber section with outside and a second release valve is provided for optionally communicating the first chamber section with outside, thereby obtaining high volume/low pressure inflation, medium volume/medium pressure inflation, or low volume/high pressure inflation.
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