Brother MFC620CN Service Manual page 119

(1) Carriage lock
Driving the purge cam pushes the carriage lock up and down. During the purge operation, the
carriage lock pops out and locks the head/carriage unit to align ink-jet units with the mating head
caps. After the purge operation, but before cleaning with the head wiper starts, the purge cam pulls
in the carriage lock and releases the head/carriage unit. When the power is off, the carriage lock is
released, pressing the head caps against the print head.
Clutch gear
Purge gear
(engaged with the
purge bevel gear)
(2) Purging
Driving the purge cam to the pump switching unit's black or color position reverses the paper feed
motor and activates the tube pump, producing negative pressure to drain the air and old ink from
the head nozzles and channels into the ink absorber box.
Air vent tube
Purge bevel gear
Tube pump
Purge lever
Idle gear L
Purge cam
Purge cam
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Maintenance unit
Vent rod unit
Carriage lock
(Front)
Black drain tube
Color drain tube
Main drain tube
(Front)
Pump switching unit
Confidential