Abstract: A guide rail or track system for guiding test tube holders or racks from one station to another, e.g., in a mono-channel analyzer, for presenting test tubes in such holders in sequence to one or more servicing operations at a plurality of stations. The rail system may comprise a main linear guide rail along which a holder having a row of test tubes supported therein is adapted to be moved longitudinally stepwise to present each test tube in the holder in sequence to a given station, or a given position therein, where an operation is to be carried out with respect to each test tube as it is presented in the station.

Abstract: The present invention is concerned wit analytical equipment comprising a centrifuge and means for introducing and/or withdrawing from the centrifuge, a carrier for liquid materials to be centrifuged in preparation for testing. The centrifuge comprises a plurality of swing supports, such as buckets or baskets, for holders or carriers of the liquids to be centrifuged, and counterweight or balancing means for assuring balanced operation even though one or more of the swing supports is or are empty while others are loaded with carriers. Provision is also made to avoid the necessity to lower a carrier for the material to be centrifuged into the centrifuge and later lifting it out. Instead, the material is supplied and discharged in a horizontal path, avoiding the lowering and lifting.