Piper Comanche PA-24 Service Manual page 720

PIPER COMANCHE SERVICE MANUAL
9-91. hletllod.
Of
Ch.ckin,
Ge ••
rator
Or
Alternatar B.lt T .... ian •
•. If properly installed, tensioned and checlce<l periodically, the pneratex or altematex drive
belt will give very satisfactory service. However. an improperly tensioned belt
will
wear rapidly
and may shp md
red~ce
prlerator or alternator
~tput. COl1aeq~eDUy,
a belt
sho~ld
be checked
for proper tension at the time it is installed, a,ain after 25 h_s operotion and each 100 holUS
thereafter
b. The:e are two satisfaC1:ory methods of checkin& belt tension; however" the Hrst
methoo
described will be found preferable
by
most maintenance per5mnel because
it
is technicaUy sizn ..
pie. and
re~ireS
linle time for ""camplisbment.
1.
Tex~e
Method: This ... thod of checkine bell tension consists ol
meas~riDg
the
tor~e
re~ired
to slip tbe belt at the '01011
p~lIey
and is accOOlplished a. folio ... :
(a) Apply a tor~e indicatine wrench to the nut that attaches the pulley to the leaerator
or alternator and tum it in
iI
clockwise direction. Observe the torque shown on the
wrench
at
the instant the pulley slips.
(b) Check the
torq~e
,ndieated ,n step (2) with torque specified ,n the following chart.
Width .f T
.,~
•• Indicated at
B.I,
Co .. c1ition G.ne,ator or Alternator py
lI.y
3/8 inch
New
11 to 13 ft. lbs.
3/8 inch Used 7 to 9 ft. lb •.
1/2 inch
New
13 to 15 ft. Ibs.
L 2 inch
Used 9 to 11
ft. lbs.
HOTE
The higher tens:cn specified for a new belt is to compensate for
the initial srretch thar rakes place as SOal as it
iJ;
operared. These
higher tenslon values should not be applied to belts which pre-
viously have been used.
2. Deflection Method: Belt tension may be checked
by
measuring the amount of deflection
caused by a predetermined amount of tenSlal; thIS is accomplished in the following manne:-:
(a) Attach the hook of a small sprin,.seale to the belt at the approximate :ludi'oint
between the :-ing gear support and the lenerator or altemator.
(b) P,ll on the .eale until a reading oi 14
po~nds
is obtained.
(10
pounds ior used
belts)
(c) ~1easure ~he disrance tile belt has mo\o·ed Rith the 10 to 14 ?Ound load applied The
disrance (deilection) should be
5."16 inch If less than 5/16 tnch. the belt is too tight.
ELECTRICAL SYSTEM
ISSUED: 8118n2
3 C20