Piper Comanche PA-24 - 9-91. METHODS OF CHECKING GENERATOR OR ALTERNATOR BELT TENSION

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