Ricoh K-C3.5L Service Training page 99

Fusing unit drive gear disengages when cover is open for easier jam removal
Fusing drive release solenoid cuts drive to fusing unit during warm-up.
Slide 99
More on Automatic Release
Pressure release when the cover is open
The drive gear releases when the cover is open, so that jams can be removed.
Pressure release during warm-up
During warm up (just after the main power is switched on, or from
standby/energy saver mode), if the temperature is above 18°C, the solenoid
turns on and disengages the drive gear, which cuts the drive to the fusing unit.
If the solenoid is off, the drive gear is engaged, and the hot roller turns whenever
the main motor is on. When the hot roller turns, it will be cooled down by the
pressure roller. So, the machine will take longer to detect the standby
temperature.
However, when the machine is cold (below 18°C), the hot roller turns so that it
will warm up evenly. Then, at 18°C, the roller will stop turning.
Note that if fusing idling is switched on (SP 1103), the solenoid will always
engage the drive gear and the rollers will turn, regardless of the temperature.
Automatic Pressure Release
Solenoid
Drive Gear
99
Model K-C3.5L
Cover