Epson DFX-8500 Service Manual page 56

Paper feed mechanism:
The paper feed motor drives the paper feed mechanism, which controls both line and form feeding.
The front, rear, and top paper end sensors detect paper in the paper path, and stop printing when there is no
paper. The printer is equipped with three paper end sensors: the front paper end sensor at the front tractor,
the rear paper end sensor at the rear tractor, and the top paper end sensor at the paper bail. The pull tractor
sensor detects whether the optional pull tractor unit is installed.
The printer is also equipped with a paper jam sensor. The control circuit reads the signals from the sensors
and indicates when an error occurs.


Tractor select mechanism:
The printer mechanism has two paper entrances: one at the front tractor and one at the rear tractor. By
controlling the ribbon feed motor, the tractor select mechanism chooses which tractor to use, and power
from the paper feed motor is conveyed to that tractor via a series of gears. The tractor select sensor detects
the selected tractor and signals that information to the control circuit. (See "Ribbon Feed and Tractor Select
Mechanisms" on page 2-10.)
Paper Bail
Printhead
Front Paper End
Sensor
Front Tractor
Sprocket
Paper
Tractor Select Sensor
Figure 2-3. Printer Mechanism Operation (2)
OPERATING PRINCIPLES
Pull Tractor
Pull Tractor Sensor
Plunger
Top Paper End Sensor
Paper Jam Sensor
Rear Paper End Sensor
Rear Tractor Sprocket
Paper Feed Motor
Ribbon Feed Motor
2-3