Paper Advance Mechanism; Paper Feeding Mechanisms - Epson LQ-870 Service Manual

2.1.3 Paper Advance Mechanism

The printer uses friction feeding to advance single-sheet paper and tractor feeding to advance
continuous paper. There are three ways to advance paper using a tractor feed mechanism: using the
push tractor, using the pull tractor, or using the push and pull tractors together. During normal operation,
the printer has one tractor that functions as either a push or a pull tractor, depending on where it is
attached to the printer. To use the push-pull tractor feed method, the standard tractor and the optional
tractor must be installed.
There are four ways to insert paper into the printer. The printer uses different paper insertion entrances
and paper paths for different types of paper. Table 2-l lists which paper insertion entrances you can
use with each paper advance method.
Paper Advance Method
Friction
Push Tractor
Pull Tractor
Push-pull Tractor

2.1.3.1 Paper Feeding Mechanisms

This section describes how the friction and tractor feed mechanisms advance paper in the printer.
Friction Feed Method
The paper is held between the platen and the paper advance roller, and between the paper eject roller
and the paper eject unit cover. The paper-feed pinion gear, turning in the direction of the black arrow,
drives the paper-feed reduction gear. The paper-feed reduction gear turns the platen gear, paper-feed
rollers, and top paper tension roller. The paper then advances in the direction of the white arrow. The
paper advance roller spring holds the paper against the platen.
Setting the release lever to the tractor feed position releases this pressure and frees the paper. Figure
2-4 illustrates friction feeding when you insert paper into the top paper entrance.
Table 2-1. Paper Advance Methods and Paper Entrances
Rear
No
OK
OK
OK
Paper Feed
Paper Feed Reduction Gear
Figure 2-4. Friction Feeding Using the Top Entrance
Paper Insertion (Paper Paths)
Front
OK
OK
OK
OK
Paper
(Cut Sheet)
Paper
Platen Gea;
Paper
Feed Motor
Pinion Gear
2-3
Bottom
No
No
OK
No
Tension Roller
Roller
Reduction Gear
Paper Feed
Motor
REV.-A
OK
No
No
N o