Abstract: An improved drive is provided for a syringe having a barrel and a plunger. The drive utilizes an electric motor which has an axial shaft that moves back and forth axially when the shaft is prevented from rotating. A syringe barrel holder is fixed relative to the electric motor housing and a plunger holder is rigidly fixed to the shaft. When the electric motor is energized, the plunger holder will move back and forth relative to the syringe barrel holder. A plurality of switches for controlling the electric motor are positioned in fixed locations relative to the motor housing. The plunger holder is operative to actuate and deactuate the switches during axial travel of the shaft.

Abstract: The input polarizer and the output polarizer of a spectrofluorometer are each mechanically identical except for the optical elements, and are constructed as modules which plug into a spectrofluorometer base. Each of the polarizer modules includes a polarizing filter that is rotatable and a self-contained motor drive for rotating the polarizing filter. Each of the motor drives comprises an electric motor mounted on the respective module, a pulley mounted on the respective module and rotatable with actuation of the electric motor, a loop coupling the pulley to the polarizing filter for rotation of the filter with rotation of the pulley, and means for enabling the filter to rotate exactly 90.degree. in opposite directions.

Abstract: A drive system for a centrifugal liquid processing apparatus or the like wherein a rotor assembly having a container for receiving a liquid to be processed by centrifugation is rotatably mounted on a rotor drive assembly, which in turn is rotatably mounted to a stationary base. Liquid communication is maintained with the container during rotation of the rotor by means of a flexible umbilical cable which extends from the container to a location external to the apparatus by way of a passageway provided in the support shaft of the rotor assembly and a guide sleeve carried on and rotatably mounted to the rotor drive assembly. The rotor assembly is rotatably driven in the same direction as the rotor drive assembly with a speed ratio of 2:1 and the guide sleeve is rotatably driven in the opposite direction with a speed equal to that of the rotor drive assembly to prevent the umbilical cable from becoming twisted during operation of the apparatus.