Methods Of Checking Generator Or Alternator Belt Tension - Piper PA-24 Comanche Service Manual

PIPER COMANCHE SERVICE MANUAL
9-91.
Meritods Of CII.eking G.n.,otor
0,
Alt.,nato,
I.lt
T.nslon.
a. If properly installed, tensioned and checked periodically. the pnerator or alternator drive
belt will pve very satisfactory service. However,
an
improperly tenlion.cf belt will wear rapidly
and may sUp and reduce pnerator or altemator output. Con_quently. a belt should be checked
for proper tension at the time it is installed. a.ain after
2S
hours operation and each 100 hours
thereafter,
b. There are two sati.factory lIIethod. of checkiftl belt tension; ftowev.r the first method
described will be found preferable by m~t
maintenance pltScnnel because it is technically sim-
ple, and requires tittle time for accCllllplishment.
1.
Torque M«hod: This method of chec:kinl belt tension con.sists t:J lIIeasurine the torque
requited to slip the belt at the small pulley and is accomplished a. follows:
(a) Apply a torque indicatinl wrench to the nut that attaebes the pulley to the lenerator
or
altemator and
tum
it in
a
clockwise direction. Ob.er\'e the torque shown on the
wrench
at
the instant the pulley slips.
(b) Check
the torque indicated in step
(2)
with torque specified in the £ol1owing chart.
Width of
T
_que Indicated at
B.lt
C.. cll tion
Gener.tor or Alt.,nator
Pull.y
3,8 inch
New
11 to 13 ft. lbs.
3/8 inch Used
7
to 9 ft. Ibs,
1/2 inch New 13 to IS ft. lbs ,
L 2
inch
Used 9 to 11 ft, Ibs.
HOTE
The hiper tension specified for a new belt is to compen'ale
for
the initial stretch that takes place as
SOat
as it is operated. These
higher tension values should not be applied to belts which pre-
Viously h.\'e been used.
2.
Deflection Method: Belt tension may
be
checked
by
me.surina the amowtt oi deflection
caused by a predetermined amount of tension: this
is
accomplished in the followinl manner:
(a) Attach the hook of a small spring-scale to the belt at the approximate :nid.point
between the ~inll gear support and the generator or altemator.
(b) Pull on the Kale until a readina of
1~
pounds is obtained, (10 pounds ior used
belts)
(c)
:"easute :he distance the belt has mO\'ed
'Nith
the 10 to 14 !,ound load applied, The
dlStanCe (deneetion) should be
5,'16 inch. If less than 5/16 inca. the belt is too tight.
ELECTRICAL SYSTEM
ISSUED: 8/18/72
3
C20
•
•
•