Specifications

E–20 Principles of Operation
Ribbon Transport System
The printer ribbon winds and unwinds continuously on a pair of spools
latched to hubs which are driven by the ribbon motors. The ribbon motors
operate only while the hammer bank assembly is running. Ribbon motion
reverses when the metal strip at either end of the ribbon crosses the left or
right ribbon guide, completing a circuit that causes both motors to reverse
direction.
Constant ribbon tension is maintained by controlling each motor with a drive
or drag circuit. While the hammer bank assembly is in motion, one motor
acts as a driving motor, drawing the ribbon against the resistance exerted by
the other motor—the drag motor. This system maintains a constant motor speed
and constant ribbon tension.
Ribbon Guide, Right
Hub Locking Latch
Ribbon Guide, Left
(Not Shown)
Ribbon Spool
Ribbon Motors
(Not Shown):
Mounted In Base
Casting
Ribbon Hub
Ribbon
Figure E–11. Ribbon Transport System