Abstract: An automatic chemistry analyzer comprises discrete sample cups about the circumference of a carousel. A motor selectively moves the sample cups towards and away from a target location where a probe is located for reciprocal vertical motion. The motion is timed for reaction with a sample cup so that when the sample cup is in position at the target location, the probe removes fluid from the sample cup. When the sample cup is moved from position, the probe aspirates fluid into an injection cell below the sample cup. A vertical motion only is imparted to the probe, while the sample cups move under the action of a single motor horizontally and laterally to define a rotational movement.

Abstract: An automatic chemistry analyzer includes sample cups circumferentially located on a sample wheel. Means moves the sample cups rotationally under cycloidal action to and away from a target location where a probe operates vertically in relation to the sample cups and an injection cell. The motion is effected by a cam operating with a cam follower formed by lobes circumferentially located about a drive wheel which houses the sample wheel or carousel.