Lincoln Electric NA-3S, Service Manual, Page: 57 / 110

MAINTENANCE
D-4 D-4
NA-3 AND NA-4
CHANGING WIRE FEED GEAR
RATIOS
Refer to Table D.1. Three gear ratios are
available: 57:1, 95:1, and 142:1. To change
the gear ratio, replace the motor pinion and
the first reduction gear per the following
instructions (Refer to Figure D.4).
FIGURE D.4 – CHANGING THE WIRE
FEED GEAR RATIO.
NOTE: Any item numbers in parentheses on
Figure D.4 refer to item numbers in the task
description breakdown.
1. Remove the four screws that mount
the adapter plate and motor assembly
to the gear box. Remove the adapter
plate and motor assembly from the
gear box.
2. Take the two long screws removed in
step 1 and screw one into each of the
tapped holes located on the face of
fiber input helical gear (12). Insert the
screws through the full thickness of
the gear, and using a screwdriver
wedged between the screws to
prevent rotation, remove hex nut (11)
that holds the gear to the shaft.
Remove plain washer (9).
3. Pull the gear from the shaft using the
screws as a pulling device.
4. Be certain woodruff key (8) is
properly located on the shaft. Screw
the adapter plate and motor assembly
mounting screws into the new fiber
input helical gear from the stenciled
side and place the gear on the shaft.
Replace plain washer (9), tighten the
hex nut (1), and remove the adapter
plate and motor assembly mounting
screws from the gear.
TABLE D.1 – WIRE FEED GEAR RATIOS.
Feed Speed* Max Wire Size
Gear Range in. (mm)
Ratio in./min (m/min)
Cored Wire Solid Wire
57:1 40-650 (12-198) 0.120 (3.0) 3/32 (2.4)
95:1 24-400 (7.5-122) 5/32 (4.0) 1/8 (3.2)
142:1 17-268 (5.2-82) 7/32 (5.6)
*
Using constant wire feed speed (CV mode).
WIRE
FEED
GEARBOX
SLOT HEAD
SCREWS
(MOUNTING
SCREWS)
HEX NUT (11)
PLAIN WASHER (9)
INPUT
HELICAL
GEAR (12)
WOODRUFF
KEY (8)