Generator Revolving Field Brushes; Generator Maintenance - Hobart Jet-Ex 4D Operation And Maintenance Manual

Table of Contents

OM-2063 / Operation and Maintenace Manual

Jet-Ex 4D / Spec. 7003A-3 and 7003B-3 / Generator Sets

8. Generator Maintenance

a. General

The only maintenance service required for the generator will be the cleaning and replacement of the

brushes and cleaning the slip rings.

b. Brush Service

If inspection reveals that brushes are gummy or sticking in the brusholders, they should be removed

and cleaned. Clean both the brushes and brusholders. Use a good, SAFE, commercial cleaner.

DRY ALL PARTS THOROUGHLY. Be sure brushes can move freely in brusholders.

WARNING

c. Generator Revolving Field Brush Replacement

(1) Disconnect leads (Fig. 7) from connectors on brusholder caps.

CAUTION

(2) Lift brush from brushholder for inspection. If brushes are worn unevenly or are shorter than 7/16

inch (11 mm) , replace them.

(3) Inspect slip rings whenever brushes are removed for servicing brushes or brusholders. 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.

(4) Slip new brushes into

brusholder 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.

(5) 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.

Chapter 2-3

Page 8

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.