| 摘要 |
A liquid dispensing mechanism is described for moving a dispensing tip from an aspirating station to a dispensing station, preferably through a circle of rotation. To move the tip first vertically, then rotationally, and then vertically, the mechanism mounts the tip and a pump on a carrier that frictionally engages a cam over which the carrier is mounted. The pump is slidably mounted for reciprocation on the carrier, and has a cam follower that extends through a slot in the carrier to the cam inside. Apparatus is provided for limiting the rotation of the carier between two circumferential positions to force the cam follower, and hence the pump and tip, to move relative to the still-rotating cam.
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