Epson FX-870 Service Manual page 122

Push Tractor Method
When the push tractor method is used with the rear entrance, the torque generated by the PF motor
is transmitted to the push tractor gear through the PF motor pinion gear, paper advance reduction
gear, and tractor reduction gear. When the PF motor pinion gear turns in the direction of the black
arrow, the tractor gear rotates in the direction of the black arrow and thus feeds the paper into the
printer. The paper is advanced by the platen and the paper tension roller, which are also driven
by the PF motor through the gear train.
When the push tractor method is used with the front entrance, the torque generated by the PF
motor is transmitted to the push tractor
reduction gear, platen gear, and the gear train in the front part of the printer. When the PF motor
pinion gear turns in the direction of the black arrow, the tractor gear rotates in the direction of the
black arrow and thus feeds the paper into the printer. The paper is advanced by the paper drive
roller and the platen, which are also driven by the PF motor through the gear train.
In the push tractor method, the release lever is set to one of the tractor positions to release the
pressure between the paper advance roller and the platen. Figure 6-5 illustrates push tractor
operation when paper is fed through the rear paper entrance. Figure 6-6 illustrates push tractor
operation when paper is fed through the front paper entrance.
Paper (Continuous)
Paper
Tension Roller Gear
Figure 6-5. Push Tractor Operation Using the Rear Paper Entrance
Epson FX-870/I 170
through the PF
gear
Paper Tension Roller
\ I
pinion gear, paper advance
motor
Tractor Reduction Gear
, P F Motor Pinion Gear
Reduction Gear
Principles of Operation
6-7