Lexmark C91x Service Manual page 219

Punch unit driving sequence
When the paper feed motor drives, the driving force is transmitted
through the punch unit drive gear to the clutch gears of the punch
unit. Since the punch clutch is normally opened OFF, the driving
force is not transmitted to the driving shaft. When the punch clutch
turns ON, it is closed and unlocked. The driving force is then
transmitted from the clutch gears to the driving shaft. As the shaft
turns, the rotation of the cam causes the paper to be hole-punched.
Immediately after one turn of the shaft, the punch clutch turns OFF,
and the drive shaft stops.
Cover
Paper
Entrance
Sensor
Registration
Roller
Cover
Punch
Clutch
Registration
Idler Roller
Registration
Clutch
5055-xxx
Drive
Shaft
Blade
Cam
Diagnostic aids
3-69