摘要 |
A carriage adapted for carrying a laboratory instrument such as a pipette, electrode, or syringe is driven by a drive shaft in the form of a lead screw. The lead screw is selectively driven by a high speed drive wheel or by a low speed drive wheel. The drive wheels are coaxially mounted around the drive shaft and concentrically and coaxially arranged with respect to one another. The drive shaft and the two drive wheels all rotate in unison in the same rotary direction.
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