Generator Disassembly, Repair And Reassembly; Field Coil Removal; Armature Service - Piper PA-24 Comanche Service Manual

PIPER COMANCHE SERVICE MANUAL
9-14. DI.......ltly, R.poit And R....... ltly. Normally, dis.sembly should procMd only so far
as is necessary to make repair or replacement of the defective part•. For 8:lample, the field coils
should be checked for opens, shorts. or IfOWld. before beiDl c.moved &om the field frame: they
should
be
removed only if they require repair or replacement.
9-15. Field C.lI R....... I. Field coil. can
be removed from the field frame taMt e..ily by IIle
of a pole shoe screw driver. It 'I alIa advisable to .... a pol. sboe .preader, .iDee this prevents
distortion of the field frame. The pole sboe .crew driver penaits euy
l~eaial
and removal of
the pole shoe .crews so that the pole shoes lIftd field coil.
CaD
be taken out of the field frame.
The pole shoe .Cntw driver and spreader should be used oa re••••mbly of the field frame. Careful
re..sembly i. lleces.ary to prevent sbortinl or IfOUIldinl of the field coils .. the pole sboes are
tilhttfted into place.
9-16. Inspectlo"
Ancl
R.poir Of PlittS.
a. The arm.nue or field should 1I0t
be
clellfted in eay depe_ial teak or by use of deere..ini
compounds, .ince tbis mieht dama. insulation so that I .hurt or IfOUftd would subsequently de-
velop. Sealed ball beannls do 1I0t require cleeailll or relubrication. Other lenerator part. should
be cleaned and carefully inspected for we., and other
dam....
ADy defective parts should
be
repaired or replaced. On reas.mbly aU sold.red electrical connections Ihould be lude with
ro.in flux. Acid flux mu.t never be u.ed on electrical COlUlectioaS.
9-17.
Fi.lcI
Coli.
a. The field coil. should be checked for pouad., opens or shorts a already explained in
paragraph
9-10.
b. Grounded field coil. may sometim.. be repaired
by
removinl them
10
th.y can be reinsu-
lated. Care must be used to avoid exc...ive bulkin••• when Ipplyinl Dew insul.tion, ,iace this
mieht cause the pole shoe to cut throulh and cal&se Mother &fOund when the coils are reinstalled.
c. Usually. if a field coil is open or shorted intlmal!y it will require replacement, .ince it is
difficult to repair such I defect.
d. To remove or replace field coil. in the field frame, the u.e of I pole .hoe sprelder and
screw driver is recommended.
9-18. Armatur.
Se"ice.
a. The annature .hould be checked for opena, shorts and IfOWlCls a. explained ill followini
p.ragraphs. If the armature commutator is wom, dirty, out of round, or h.. hip lIIica, the armature
should be put in a lathe so the commutator can be turned down and the mica unden:;.ut. The mica
should be undereut
li32
of an inch and the .lotl cleazsed out carefully to telIIove any trace of dirt
or copper dust. As a fillSl step in this procedure, the commutator should be .anded lilhtly with
No.
00
sandpaper to remove any slilht burrs that llIipt be left a • result of the Llildercuttillg
procedure.
b. Open cireuited arm.tures can often be
s.ved when the open is obvioul and rep.irable. The
most likely place an open
will
occur is at the cOllllllutator riser bars: this ulu.lly results from
overloadinl of the pIlarator, whieh caul.. overheatiftl and meltinl of the solder. Rep.ir can be
effected
by
feselderinl the lead. in the riler bars (Ulinl rMin flux) and tuminl down the com-
mutator in a lathe to remove the burned spot ud then \lDdercuttial the mica IS explained in the
previous par'lraph. 111 some heavy-duty· armatures the l•• ds are welded into the ri.er b.rs, and
these cannot. of course, be repaired
by
resolderinl.
ELECTRICAL SYSTEM
ISSU ED: 8/18/12
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