Lincoln Electric LF-72/74 service manual Required Equipment, BB-3

BB-3 OPERATION BB-3

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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.

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.

LF-72/74