Generator Maintenance; Brush Service; Generator Revolving Field Brush Replacement - Hobart Jet-Ex 5D Operation And Maintenance Manual

OM-2094 / Operation and Maintenance Manual
Jet-Ex 5D / Series 500285/ Generator Set

Generator Maintenance

8.
a. General
The only maintenance service required for the generator will be brush replacement, slip ring
cleaning, etc.
b. Brush Service
If inspection reveals that brushes are gummy or sticking in the brush holders, they should be
removed and cleaned. Clean both the brushes and brush holders. Use a good, SAFE, commercial
cleaner.
DRY ALL PARTS THOROUGHLY. Be sure brushes can move freely in brush holders.
CAUTION
c. Generator Revolving Field Brush Replacement (See Figure 4)
(1) Disconnect leads (A, Fig. 4) from connectors on brush holder caps (B).
(2) Remvoe brush holder caps (B) from brusholder.
WARNING
(3) Lift brush (D) from brush holder (C) for inspection. If brushes are worn unevenly or are shorter
than 7/16 inch (11 mm), replace them.
(4) Inspect slip rings whenever brushes are removed for servicing brushes or brush holders. Note
surface conditions of rings. Surface should appear smooth and clean. Scoring or roughness of
slip rings may be caused by grit or abrasive substance in brushes, or by oil on the rings.
Moderately rough slip rings can be smoothed by holding grade 00 flint paper against their
surface while the rings are revolving slowly. If the rings are badly scored, the unit must be sent
to an overhaul facility for repair. After cleaning slip rings, blow dirt and grit out of the unit with
compressed air. Do not use over 25 psi (172 kPa) air pressure to blow dirt out.
(5) Slip new brushes into brush-holder guides, and place caps on top, and screw them into the
guides to a "bottomed" position. The spring attached to the brush will determine the pressure at
which the brush contacts the slip rings.
(6) To fit new brushes to the slip rings, lay a strip of No. 00 sand- paper, smooth side down, on slip
ring surface, and draw the sandpaper in the direction of rotation of the slip ring, lifting the brush
on the return stroke. Continue until the brushes have same curvature as the slip rings. Blow all
carbon dust out of the machine using not over 25 psi (172 kPa) air pressure.
November 1, 2000
Revised 08/01
DO NOT use a flammable solvent. DO NOT use steam cleaner, or soaps and
detergents under pressure.
When removing the lead wires, do so one at a time and replace each brush
accordingly, to insure that the lead wires are put pack onto the proper brushes.
Chapter 2-2
Page 7