Brother MFC640CW Service Manual page 46

First, the paper feed motor rotates counterclockwise (when viewed from the output gear side). The
motor rotation passes to the PF roller gear L and, via the ejection idle gear, the ejection roller gear
to rotate the paper feed and ejection rollers in the reverse direction.
At the right end of the paper feed roller is the PF roller gear R which is always engaged with the
clutch gear and the idle gear L. The latter transmits the motor rotation via the idle gears S and the
paper pull-in gear shaft to the paper pull-in roller holder so that the paper pull-in roller pulls in a
sheet of paper.
While the paper pull-in roller pulls the paper, the paper feed roller rotates in the reverse direction to
align (register) the leading edge of the paper.
Registration sensor activation switches the paper feed motor to clockwise rotation to rotate the
paper feed roller in the forward direction to feed the paper. During this paper feed operation, the
planetary gear inside the paper pull-in roller holder prevents rotational torque from reaching the
paper pull-in roller.
The above paper pulling-in and feeding operations take place when the head/carriage unit is in
printing operation. When the head/carriage unit reaches the purge position, the clutch gear becomes
disengaged from the idle gear L and engaged with the purge gear. For further details on the head
maintenance mechanism, see
Paper feed roller
Paper feed motor
PF roller gear L
PF motor gear
Ejection
idle gear
Paper ejection
roller gear
Section 3.2.2.3.
Jam clear cover
Paper pull-in
roller holder
3-8
Clutch gear
Purge lever
PF roller gear R
LT gear
Purge gear
Idle gear L
Paper pull-in gear shaft
Paper tray
(Front)
Confidential
Idle gears S