Ricoh BR-C1a Basic Service Training page 233

 At each end of the lubricant bar, there is a near-end detection
mechanism.
 If either sensor is triggered, near-end is detected.
 Then, at a certain amount of drum rotation, end is detected, and
the machine stops.
Slide 233
Copied from CH-C1
Lubricant Near-end Detection
Overview
233
BR-C1 Training