Epson FX-870/1170 - Manual (Page 125)

Principles of Operation
Push-pull Tractor Method
The push-pull tractor method is a combination of the push and pull tractor methods. Two tractors
are used to advance the paper: one at the front paper entrance and the other at the rear paper
entrance. They operate simultaneously to push and pull the paper through the printer mechanism.
Figure 6-8 illustrates push-pull tractor operation when the paper is fed through the rear paper
entrance. Figure 6-9 illustrates push-pull tractor operation when the paper is fed through the front
entrance.
Paper (Continuous)
Pull Tractor
Pull Tractor Gear
Push Tractor
Push Tractor Gear
Tractor Reduction Gear
,PF Motor Pinion Gear
Motor
Paper Advance
Reduction Gear
Figure 6-8. Push-pull Tractor Operation Using the Rear Paper Entrance
6-10 Epson