Oki C7400n Service Manual page 30

(6) Duplex Unit
1. When the duplex unit receives an instruction from the printer to print on both sides of a
sheet of paper, the solenoid opens the separator after the completion of one side printing
of a sheet of paper sent from the tray. The path is switched to that to the duplex unit.
At this time, as the roller (1) turns in the direction of the arrow "a," the paper is retracted
on the rear of the cassette.
2. When fixed time has elapsed after the paper beginning passes through the duplex-in
sensor, the rollers reverse and the roller (1) turns in the direction of the arrow "b" to feed
the paper into the duplex unit. After that, the paper passes through the rollers (2), (3) and
(4), and ejected with the other side printed, and fed again into the printer.
41316401TH Rev.4
Roller(4) Roller(3)
Figure 2-11
Separator
Solenoid
Duplex-in sensor
b
a
Motor
Roller(2) Roller(1)
30 /