UBI EasyCoder 601 XP – Service Manual Ed. 1
34
Chapter 7 Transfer Ribbon Mechanism
Working Principles
The ribbon unwind unit is braked by a spring affixed to the printer's
centreline wall, partly enveloped by a sleeve affixed to the shaft.
Initially, the spring expands towards the inner walls of the sleeve,
thereby breaking the rotation of the shaft. When the bobbin is forced
to rotate (i.e. 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 125
±
10 Nmm
1
. The sleeve is filled 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 – 10 million
print cycles.
When the rotating force ceases, the spring tends to pull back the
ribbon, keeping it tight.
The code disc is used in connection with the optional ribbon low
sensor (see chapter 12).
Dismantling
The shaft rotates in bearings fitted into a flange, which is attached
to the centre-line wall by two #T20 Torx screws inserted from the
electronics compartment. Before the unit can be pulled out, the
sleeve/spring package must be removed. Use a 2 mm hexagon
wrench to loosen the grub screw.
Bobbin assy.
Sleeve
Circlip
Circlip
Brake Spring
Bearing
Bearing
Flange
Shaft
Grooves
Grub Screw (M4)
Plastic Circlip
Code Disc
7.2 Ribbon Unwind
Unit,
cont'd.
1
/. Refer to Appendix 2 for a description of
how to check the brake torque.
