Ricoh B205 Service Manual page 399

PHOTOCONDUCTOR UNIT (PCU)
[A]
6.7.2 DRIVE
[E]
[B]
[C]
[D]
The main motor [A] drives the drum [B] through a series of gears, a timing belt [C],
and the drum drive shaft [D]. The main motor assembly includes a drive controller,
which outputs a motor lock signal when the rotation speed is out of the specified
range.
The fly-wheel [E] on the end of the drum drive shaft stabilizes the rotation speed
(this prevents banding and jitter from appearing on copies).
SM 6-39 B205/B209/D007/D008