Pumps; The Pumps - Bayer HealthCare RapidPoint 400 Series Service Manual

Pumps

The pumps move the reagents, samples, and wash reagent through the
Rapidpoint 400 series systems. The sample pump moves the sample and
the reagents through the system. The sample pump also moves KCl
through the reference electrode. The wash pump delivers a mixture of
wash fluid and air to the sample entry port.
Each pump consists of a roller cage, a motor, a pump housing, a motor
mount, a spring plate, and springs. The roller cage presses onto the motor
shaft.
The pump that services the measurement cartridge generates flow by
compressing the tubing against the fixed platen of the cartridge. As the
individual rollers rotate through the platen area, a segment of the tubing is
pinched in two places by adjacent rollers. The fluid is pushed through the
tubing by the peristaltic action of the moving rollers.
A stepper motor drives each pump. Each motor moves 1.8 degrees per
step and 200 steps per revolution. The electrical drive and control for the
pump stepper motors are provided by a microstepping circuit on the main
board. The software controls the speed and direction of each pump.
Stepper Motor Components
52 Rev. C