Intermec EasyCoder PX4i Service Manual page 62

Chapter 7 — Transfer Ribbon Mechanism
Working Principles
Grub screw
Brake sleeve
Ball bearing
Flange
Ball bearing
52
The ribbon supply is braked by a spring affi xed to the printer's center sec-
tion, partly enveloped by a sleeve affi xed to the shaft. Initially, the spring
expands towards the inner wall of the sleeve, thereby breaking the rotation
of the shaft. When the bobbin is forced to rotate (that is, when the ribbon
is unwound), the breaking spring is compressed. After approximately half
a turn, the diameter of the spring has been compressed enough to allow
the sleeve to slip. The brake torque should be 55 ±5 Nmm (see Appendix
C). The sleeve is fi lled with ball bearing grease. If the brake torque deviates
from the recommended value, replace the grease. We recommend Castrol
Sinplex 2. The expected interval between replacing the grease is 8 to 10
million print cycles.
When the rotating force ceases, the spring tends to pull back the ribbon,
keeping it tight.
Torque spring
(diff ers between
models)
Shaft
Grooves
Grub screw
Locking washer
Locking washer
Code disc
Pivot assy.
EasyCoder PX4i and PX6i Service Manual
Fixing ring