Epson DFX-8500 Service Manual page 57

OPERATING PRINCIPLES
‰Paper feed mechanism :
The CR motor controls printing in the horizontal direction, and the paper feed mechanism controls movement
in the vertical direction (line feeding and form feeding). The paper feed mechanism feeds paper vertically.
The PF motor drives the paper feed mechanism.
The front, rear, and top PE sensors detect whether paper is present in the paper path, and stop the printer
from printing when there is no paper. The printer is equipped with three PE sensors: the front PE sensor at
the front tractor, the rear PE sensor at the rear tractor, and the top PE 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 RF motor, the tractor select mechanism chooses which tractor to use, and power from the PF
motor is conveyed via a series of gears. The tractor select sensor detects the selected tractor and signals
that information to the control circuit.
Figure 2-3. Printer Mechanism Operation 2
2-3
Rev. B