TP-5986 4/03 31Section 7 Generator Troubleshooting
7.5 Brushes
The brushes provide a current path from the voltage
regulator to the collector rings. Because the brushes
carry a low current, inspect them every
1000--1500 hours. Abrasive dust on the collector rings
could, however, shorten the life of the brushes.
Excessive arcing at the brushes could damage the
voltage regulator. Weak springs, damaged collector
rings, sticking brushes, a loose holder, or poor brush
contact can cause arcing at the brushes.
The brushes must be free to move within the holder and
be held in contact by the springs. When properly
positioned, spring pressure on the brush surface will
cause the brush to wear evenly. Brushes must ride
100% on the collector rings or arcing will occur and
cause burned rings or failure of the voltage regulator.
Figure 7-9 shows the correct positioning of the brushes.
Add or remove spacers as necessary to center brushes
on collector rings. Replace brushes if they show
excessive or uneven wear.
TP-598657
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2
3
4
1. Correct position
2. Brush holder
3. Incorrect position
4. Generator collector rings
Figure 7-9 Brush Positioning
Use a retainer wire (such as a paper clip) to contain the
brushes during disassembly and reassembly. Push the
brushes into the brush holder until the retainer wire can
be inserted into the brush keeping hole. See
Figure 7-10. Replace brushes when they are worn to
half of their original size.
TP-598658
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2
3
4
5
6
1. Brush holder
2. Retainer (paper clip)
3. Mounting screw
4. Alignment shim(s)
5. Brush
6. Spring
Figure 7-10 Brush Holder
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