Brother MFC990CW Service Manual page 105

(5) Head wiper mechanism
After the purge operation, the purge cam pushes up the head wiper, wiping off any ink
remaining on the head nozzle surface as the head/carriage unit moves from right to left.
Purge gear
(Cap lift cam gear)
(ASF changeover gear)
Head wiper
Purge cam
(3_15)
Confidential
3-28