machine, use a throttling valve to reduce the
pressure. Always blow out any accumulation of water
in the air lines before directing the airstream on the
part or ma-chine to be cleaned. Be certain that the
The following paragraphs will discuss some of the
compressed air does not have any grit, oil, or
procedures to follow when performing maintenance
moisture content in it. Compressed air should be used
and repair on motor generators.
with caution, particularly if abrasive particles
(carbon, and so on) are present, since these may be
driven into the insulation or may be forced beneath
insulating tapes or other possible trouble spots. If
Brushes used in electric motors and generators are
vibration exists, check for loose parts or mounting
constructed of one or more plates of carbon, riding on a
commutator, or collector ring (slip ring), to provide a
Motors, generators, and other electrical equipment
passage for electrical current to an internal or external
that have been wet with salt water should be flushed
circuit. The brushes are held in position by brush
out with fresh water and dried. Never let the
holders mounted on studs or brackets attached to the
equipment dry before flushing with fresh water. For
brush-mounting ring, or yoke. The brush holder studs,
complete information on washing and drying
or brackets, and brush-mounting ring comprise the
procedures, refer to NSTM, chapter 300.
brush rigging. The brush rigging is insulated from, but
The key points in the maintenance of electric
attached to, the frame or one end bell of the machine.
generators and motors are as follows:
Flexible leads (pigtails) are used to connect the brushes
to the terminals of the external circuit. An adjustable
Keep insulation clean and dry.
spring is generally provided to maintain proper pressure
of the brush on the commutator to effect good
Keep electrical connections tight
Figure 3-9.--Brush holder and brush-rigging assembly.