Tweco 251 Thermal Arc Fabricator - Manual (Page 34)

FABRICATOR 251
INSTALLATION 3-12 Manual No. 0-4847
Art # A-07162
Wheel Brake Hex Head Bolt
Spool Hub Nut
Pressure Adjustment
Device
Figure 3-12: Wire Installed
3.13 Wirefeeder Drive Roller Pressure Adjustment
The roller on the swing arm applies pressure to the grooved roller via an adjustable tension devise. The Tension
Adjuster should be set to a minimum pressure that will provide satisfactory wire feed without slippage. If slipping
occurs, and inspection of the wire out of the MIG gun reveals no deformation or wear, the conduit liner should be
checked for kinks or clogging from metal flakes. If this is not the cause of slipping, the feedroll pressure can be
increased by rotating the Tension Adjusting knob clockwise. The use of excessive pressure may cause rapid wear of
the feed roller, motor shaft and motor bearings.
NOTE
Genuine TWECO contact tips and liners should be used. Many non-genuine liners use inferior materials
which can cause wire feed problems.
3.14 Wire Reel Hub Brake
The wire reel hub incorporates a friction brake which is adjusted during manufacture for optimum braking. If it is
considered necessary, adjustment can be made by turning the hex head bolt inside the open end of the wire reel hub.
Clockwise rotation will tighten the brake. (Refer to Figure 3-12 above).
CAUTION
Excessive tension on the brake will cause rapid wear of mechanical wire feed parts, over heating of electri-
cal componentry and possibly an increased incidence of wire Burnback into the contact tip.
NOTE
Correct adjustment will result in the wire reel circumference continuing no further than 0.75" (20mm) after
release of the Gun trigger switch. The wire should be slack without becoming dislodged from the reel.