| 摘要 |
The present invention is concerned with a dual stroke drive mechanism of any size for a reciprocating device, such as a piston of a pump. It is particularly concerned with such a driving mechanism having means for selecting a particular stroke-length. It is more specifically concerned with a drive mechanism capable of imparting either one of two set stroke-lengths and means for selecting one of the stroke lengths before, or at certain intervals during, operation of the mechanism. The drive mechanism converts rotary movement of an input member into reciprocating rectilinear movement of an output member which may be connected to a piston and reciprocates the latter. A preferred application is in the field of sampling pumps for distributing liquid samples of small sizes into vials for analysis.
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