Xerox Phaser 8400 Service Manual page 45

A closed-loop servomotor drives the drum assembly. Through a single reduction belt
drive, the servomotor rotates the drum at a high speed for imaging and a constant low
speed for image transfer to paper. The Y-Axis uses an active tension system to allow
the pulley to float while the spring actively adjusts the tension.
Note
The drum rotates in different directions for each process.
■
Transfix CW
■
Maintenance CCW
■
Printing CCW
Single Reduction Belt Drive
Pulley
Tension Spring
Warning
Theory of Operation
CW
CCW
Y-Axis Motor
Always keep your fingers away from the drum drive system; it
uses a closed-loop servo drive system, which is inherently
dangerous. Since the motor speeds up if it senses the drum drive
system slowing down, fingers caught in the drum belts and gears
can be severely injured.
Drum Temperature Sensor
Fan
Y-Axis
Encoder
Air Direction
8400
8500/8550
s8500-020
2-17