Lincoln Electric NA-3S, Service Manual, Page: 58 / 110

MAINTENANCE
D-5 D-5
NA-3 AND NA-4
FIGURE D.5 – DRIVE MOTOR PINION
GEAR REMOVAL.
5. After noting the relation of the adapter
plate with the motor leads, remove
the adapter plate from the wire drive
motor. See Figure D.5. Support the
pinion properly and, with the proper
size punch, drive the roll pin that
holds the pinion out of the shaft. Pull
the pinion off. Install the new pinion
and replace the roll pin. Replace the
adapter plate in its original location.
6. Cover the teeth of the motor pinion
and the input gear with a non-fluid
molydisulfide grease such as Non-
Fluid Corporation’s A-29 Special/MS
Lubricant. This grease can be
scooped from the cavity of the gear
case.
7. Reassemble the motor on the gear
box; make sure the gears mesh
properly and the adapter plate
locating bead is in its cavity. Replace
and tighten the four screws removed
in step 1.
WIRE DRIVE MECHANISM
Drive mechanisms for three wire size ranges
are available: 0.035 through 0.052 in.
(0.9 through 1.3 mm), 1/16 through 3/32 in.
(1.6 through 2.4 mm), and 3/32 through
7/32 in. (2.4 through 5.6 mm). If changing to
wire sizes outside this range, change the
drive rolls and the incoming and outgoing
guide tubes. Also change the gear ratio as
necessary.
The electrode is driven by gripping between
the grooved drive rolls and spring-loaded
idle roll. Replace the drive rolls when they
become worn. The drive rolls for 1/16 in.
(1.6 mm) and larger diameter electrodes
have two sets of teeth so they can be
reversed once before they must be replaced.
WIRE STRAIGHTENERS
SOLID ELECTRODE
Periodically inspect the slide bushing at the
top of the straightener and the ingoing wire
guide at the bottom of the straightener for
signs of wire milling. If necessary, rotate the
guide to present an unworn surface. To
reverse the slide bushing for a fresh wear
surface, remove the cross adjustment screw
and turn the bushing over.
FLUX-CORED ELECTRODE
Severe wear at the “V” groove in the curved
arm of the straightener can result in wire
wander at the arc. Periodically check the
groove and replace the arm when badly
worn. Also replace the ingoing guide at the
top of the straightener if it shows signs of
wire milling.
WIRE
DRIVE
MOTOR
SHAFT
ADAPTER
PLATE
PINION
ROLL
PIN
MOUNTING
SCREW (x3)