Lincoln Electric LF-72/74 Welder User Manual


 
LF-72/74
OPERATION
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General Functional Description
The LF-74 fulfills the need for an economical wire feed-
er with a high performance wire drive. Functional fea-
tures included are those that offer the most value – a
WFS knob with a calibrated printed scale, cold-feed/
gas purge switch, trigger interlock switch and tachome-
ter motor control.
RECOMMENDED PROCESSES
GMAW
FCAW
PROCESS LIMITATIONS
The LF-74 is not recommended for GMAW-Pulse
Synergic, GTAW, GTAW-Pulse, CAG, SMAW
The LF-74 is not compatible with push-pull equip-
ment.
For the heavy duty bench models K2426-2 and
K2426-3, the maximum spool size = 60 lb. (27.2 kg).
REQUIRED EQUIPMENT
Lincoln’s LF-74 is designed for use with the CV and DC
family of power sources. These include:
• CV-250 • DC-400
CV-300 • DC-600
CV-305 • DC-655
CV-400 • Invertec V350
• CV-655
OTHER COMPATIBLE POWER SOURCES
Ranger 250
• Ranger 305
• Commander 300
• Vantage 300
• Vantage 500
Air Vantage 500
EQUIPMENT LIMITATIONS
Maximum GMAW gun length = 25’ (7.6m)
• Maximum FCAW gun length = 15’ (4.6m)
• Maximum conduit length = 30' (9.1m)
• Maximum total control cable length = 100ft (31m)
• The LF-74 operates on 24-42VAC and not 115 VAC
The K1733-1 and K1733-3 wire straighteners are not
compatible with the LF-74
Gun bushings are required for welding guns that do
not have a Magnum (Tweco #2-#4 compatible) back
end.
• The LF-74 does not attach to K303 or K377 wire reel
stands.
PRODUCT DESCRIPTION
General Physical Description
The LF-74 is optimized for GMAW and FCAW welding.
The powerful 4 roll MaxTrac™ drive, heavy duty enclo-
sure and wire reel stand combine to make an easy to
install, easy to use wire feeder for everyday welding.
Powering the wire drive is a high performance motor
gearbox. A heavy duty hinged door opens easily, which
provides an ample amount of room for assembling pre-
cision drive components and the welding gun.
MaxTrac™ technology delivers great feeding because:
Patent pending drive rolls improve traction.
The precision machined, rigid aluminum alloy frame
results in maximum drive roll clamping pressure.
Drive hubs with steel inner cores have 3 ball bear-
ings inside each hub.
The drive hubs are supported by large, heat treated
and ground shafts for maximum rigidity and accurate
drive roll alignment.
Patent pending dual spring pressure arms have sen-
sitivity for feeding soft wires without crushing them,
and have plenty of compression force for feeding
solid or stiff wires.
Easy to configure, easy to service parts give
MaxTrac™ drives the edge in productivity.
Patented split wire guides fully support the wire and
virtually eliminate birdnesting.
No tools required to change the drive rolls and wire
guides.
Changeable gun bushings easily accept guns from
many manufacturers.
Brass-to-brass connections between the electrode
connection and the gun minimize voltage drop varia-
tions, resulting in consistent arc performance all day,
every day.
Three models of the LF-74 are available to satisfy
many customer set-ups:
The base model is enhanced for GMAW welding with
consumables from bulk packages or when a boom
mounting is required.
The bench model with heavy duty wire reel stand tar-
gets operators performing GMAW or FCAW welding
using consumables on spools.
The high torque model features high ratio gearing for
feeding larger diameter FCAW or GMAW wires.
All models use a high performance motor-gear box
with an integrated tachometer.