Lincoln Electric SVM194-A 55TROUBLESHOOTING and REPAIRF-55, Pitted and Are Damaged Commutator

Section TOC Master TOC

F-55TROUBLESHOOTING AND REPAIRF-55

WELDING GENERATOR BRUSH AND COMMUTATOR

INSPECTION AND SERVICE PROCEDURE (continued)

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Pitted and Are Damaged Commutator:

If pitting and arc damage to the commutator is evi- dent, the machine may have been used with badly worn brushes. The brush spring tension may have been too low, or the brushes may have been stick- ing in the holders. An out-of-adjustment rocker or a serious overload may also cause this condition.

• Examine the inside of the brush clovers and other parts that are close to the commutator. If there is a significant amount of solder and debris that has been thrown from the commu- tator, the armature will need to be replaced and the stator coils must be carefully examined and tested for damage.

• Perform the Weld Circuit Ground and Short

Circuit Test.

• If the brushes are worn out, replace them and re-surface or clean the commutator as needed. If the brush springs appear weak, or damaged in any way, replace them as well. The brush holder plates and retainers should be clean, smooth, and undamaged so the brushes can move freely as they wear.

• Check the rocker position. Be certain that it is aligned with or very close to the factory drill mark. See Figure F.3.

IMPORTANT: If the rocker position requires adjust- ment, do not over tighten the rocker clamping screw. This screw should be tightened to a torque of 70 to 75 Inch-Lbs. Over tightening can destroy the rocker.

Uneven Commutator appearance:

If the commutator appears to have some normal colored bars and some blackened bars, the arma- ture may be shorted.

• If excessive sparking is observed and/or the weld output is abnormal, the armature should be replaced.

• If the commutator has uneven color, but there is no sign of serious generator performance prob- lems, the commutator may only need to be cleaned by lightly stoning the surface. See cau- tion note on commutator stone usage.

Examine the brushes:

The brushes and springs should all be in place and not be excessively worn. Brushes should be replaced if they are worn to within 1/4" of the pigtail lead.

The pigtail lead of each brush should be positioned so it allows free movement of the brush while it wears.

The brushes should be seated so that the face of each brush makes 95% minimum contact with the commutator. Lightly stone the commutator to seat the brushes. See caution note on commutator stone usage.

Examine the brush holders:

The brush holder insulators must be clean and in good condition and all of the hardware must be in place. Replace any insulators that are cracked or damaged in any way.

When installing the brush holders, they should be rotated toward the brush retainer (clockwise rota- tion when facing the brush holder mounting screw.) until they stop. The edge of the brush holder plate should be parallel with the surface of the commu- tator and positioned .030 to .090 from the surface of the commutator. The brush holder mounting screw should be tightened to a torque of 24 to 28 Ft Lbs.

The brush holder plate and retainer assembly must be clean and smooth. Nothing should prevent free movement of the brushes. All electrical connec- tions to the brush holders must be clean, and tight. The recommended torque for 5/16-18 brush holder connection screws is 8 Ft-Lbs.

CLASSIC® 300D & 300G