Piper Comanche PA-24 Service Manual page 689

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PIPER COMANCHE SERVICE MANUAL
CAUTION
Do not strike the diode. as the shock may damage the other diodes.
9-51. 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 in a lathe. or otherwise spin the rotor. and hold the polishing cloth agamstthe
slip rings until they are clean. .
CAUTIO]\;
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.
Slip rings which are rough or out of round should be turned in a lathe to .002 inch maximum indicator
reading. Remove only enough material to make the rings smooth and round. Finish with 400 grain or
flfOi
polishing cloth and blow away all dust.
9-52. Bearing Replacement And Lubrication. The bearing in the drive end frame can be removed by
detaching the retainer plate screws. and then pressing the bearing from the end frame. If the bearing is in
satisfactory condition. it may be re-used. and it should be filled one-quarter full with Delco-Remy lubricant
No. 1960373 before reassembly.
CAUTIO]\;
Do not overfill. as this may cause the bearing to overheat. Use only
1960373 lubricant.
To install a new bearing. press in with a tube or collar that just fits over the outer race. It is recommended
that a new retainer plate be installed if the felt seal in the retainer plate is hardened or excessively worn.
The bearing in the slip ring end frame should be replaced if its grease supply is exhausted. No attempt
should be made to re-Iubricate and re-use the bearing. To remove the bearing from the slip ring end frame.
press out with a tube or collar that just fits inside the end frame housing. Press from the outside of the housing
towards the inside.
To install a new bearing. place a flat plate over the bearing and press in from the outside towards the
inside of the frame until the bearing is flush with the outside of the end frame. 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.
Saturate the felt seal with S.A.E. 20 oil. and then reassemble the felt seal and steel retainer
9-53. Brush Replacement. When the slip ring end frame assembly is separated from the rotor and drive end
frame assembly. the br.ushes will fall down onto the shaft and come in contact with the lubricant. Ifthe brushes
are to be re-used. they must be thoroughly cleaned with a soft dry cloth. Also. the shaft must be thoroughly
cleaned before reassembly.
The brush springs should be inspected for any evidence of damage or corrosion If there is any doubt as
to the condition of the brush springs. they should be replaced.
ISSUED: 8/18/72
3813
ElECTRICAL SYSTEM