Brother Laser MFC-4800, Service Manual

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3-5
Paper pulling-in and registration mechanism
The paper pulling-in and registration mechanism consists of the pull-in roller gear (incorporated in
the auto sheet feeder ASF), planetary gear system, paper feed solenoid, solenoid lever, clutch
release lever, and registration sensor. (For the details about the sensor, refer to Subsection 3.2.3.)
If the main motor rotates clockwise, the rotation is transmitted to the intermediate gear of the
planetary gear system. As the intermediate gear rotates, the pull-in roller drive gear also rotates
since the clutch gear is locked by the solenoid lever and the clutch release lever. Accordingly, the
pull-in roller in the ASF rotates to pull in paper into the machine, a sheet at a time.
If the paper feed solenoid is retracted and the clutch release lever is operated according to the cam
profile of the pull-in roller drive gear so as to release the clutch gear, the clutch gear rotates and
the pull-in roller drive gear does not rotate. This way, the clutch gear switches the transmission of
the motor rotation to the pull-in roller drive gear on and off.
The solenoid on/off timing and the clutch release lever timing allow this mechanism to pull in a
sheet and register it against the registration roller.
Paper feeding and ejecting mechanism
If the main motor rotates clockwise, the rotation is transmitted via the gear train to the drum drive
gear, heater roller drive gear, and paper ejection roller drive gear.
After the paper passes through the heat-fixing process, it will be ejected onto the paper tray.
If the leading edge of the paper pushes up the actuator of the paper ejection sensor, the
photosensor becomes opened, signaling the start of paper ejection. If the trailing edge has passed
through the sensor actuator, the sensor becomes closed, signaling the completion of paper ejection.
Then, the main motor stops rotation.