Rockwell Automation 1325R Small DC Motors User Manual - Manual (Page 6)

6 Small DC Motors
Bearings
Ball bearings are deep grooved, double shielded with sufficient lubricant
packed into the bearings by the manufacturer for “life lubrication.” The
initial lubricant is supplemented by a supply packed into larger reservoirs in
the end shield at time of assembly. No grease fittings are provided. The
initial lubrication is adequate for up to 5 years of operation under normal
conditions.
Should it become necessary to replace bearings, the bearing bore and cavity
should be thoroughly cleaned and repacked with approximately 1/2
teaspoonful of recommended grease.
Bearings should be removed with bearing pullers using a center insert in the
end of the shaft to protect the shaft center. To reinstall ball bearings, either
in a press or on the bench, pressure should be applied to the inner race by
using a square faced sleeve or piece of pipe that will fit over the shaft, to
avoid damaging the bearing. If a press is not available and a hammer is
used, the blows should be transmitted against the sleeve by a block of wood
or fiber.
Brushes
Check brushes to make certain that they move freely in the holders and
make proper contact with the commutator. Re-place worn brushes. Give
complete motor identification when ordering parts. New brushes should be
pre-radiused to fit the commutator curvature. Blow out the carbon dust.
Short brush life and poor commutation may be due to a rough commutator,
a shorted armature, or poor undercutting of mica. Dirt and chemicals in the
air are common causes of trouble.
Commutator
The commutator should remain a polished surface. Blackening may indicate
rough or eccentric commutator. Occasional wiping (power off) with dry
canvas or non-linting cloth may suffice. If rough or excessively dirty,
smooth with very fine (00) sandpaper lightly with armature rotating. Never
use emery cloth. Never allow the brushes to wear so short that spring
tension is lost. The resultant sparking will seriously damage the
commutator.
If frequent dressing is required, the cause should be found and corrected. A
very rough commutator should be turned in a lathe, at high speed, with a
sharp tool. Do not remove more copper than necessary. The mica should be
undercut if necessary.
An authorized service shop is recommended for this work.