Slip Ring Servicing
If the slip rings are dirty, they may be cleaned and
finished with 400 grain or finer polishing cloth. Spin the
rotor and hold the polishing cloth against the slip rings
until they are clean.
The rotor must be rotated in order
that the slip rings will be cleaned
evenly. Cleaning the slip rings by
hand without spinning the rotor may
result in flat spots on the slip rings,
causing brush noise.
Fig. 14 - Slip Ring End Bearing Assembly.
Slip rings which are rough or out or round should be
The bearing in the slip ring end frame should be
trued in a lathe to .002 inch maximum indicator reading.
replaced if its grease supply is exhausted. No attempt
Remove only enough material to make the rings smooth
should be made to re-lubricate and reuse the bearing.
and round. Finish with 400 grain or finer polishing cloth
To remove the bearing from the slip ring end frame,
and blow away all dust.
press out with a tube or collar that just fits inside the end
frame housing. Press from the outside of the housing
The bearing in the drive end frame can be removed by
towards the inside.
detaching the retainer plate screws, and then pressing
To install a new bearing and separate seal place a flat
the bearing from the end frame. Fig. 13.
plate over the seal and press in from the outside toward
the inside of the frame until the seal is flush with the
outside of the end frame (Fig. 14). Press the seal in
with the lip of the seal toward the rotor when assembled,
that is, away from the bearing. Place the flat plate over
the bearing and push in both bearing and seal so
bearing is flush with outside of end frame. If seal is
integral with bearing, simply press bearing in as
Support the inside of the frame with a hollow cylinder to
prevent breakage of the end frame. Use extreme care
to avoid misalignment or otherwise placing undue stress
on the bearing. Lightly coat the seal lip with oil to
facilitate assembly of the shaft into the bearing.
Reassembly is the reverse of disassembly.
Remember when assembling the pulley to secure the
rotor in a vise only tight enough to permit tightening the
shaft nut to 40-60 lb. ft. If excessive pressure is
applied against the rotor, the assembly may become
distorted. To install the slip ring end frame assembly to
the rotor and drive end frame assembly, remove the
Fig. 13 - Drive End Bearing Assembly.
tape over the bearing and shaft, and make sure the
To install a new bearing, press in with a tube or collar
shaft is perfectly clean after removing the tape. Insert a
that just fits over the outer race, with the bearing
pin through the holes to hold up the brushes. Carefully
assembled into the end frame as shown in Fig. 14.
install the shaft into the slip ring end frame assembly to
avoid damage to the seal. After tightening the thru-bolts
remove the brush retaining pin to allow the brushes to
fall down onto the slip rings.
To check the alternator in a test stand, proceed as
1. Make connections as shown in Fig. 15, except leave
the carbon pile disconnected.