5. Check belt and pulley alignment of compressor and alternator as follows:
a. A datum line must be established for checking belt and pulley alignment. A nominal dimension
must be established between forward edge of compressor belt and forward machined surface of
ring gear. This dimension should be taken at ring gear assembly where belt is in its sheave. The
amount of misalignment can then be determined at other pulley sheaves by using a stiff
straightedge of sufficient length to extend from front of ring gear to component sheaves.
—NOTE—
Ensure adequate ring gear surface contact to provide a solid base
for straightedge.
b. Obtain a basic measurement from top of ring gear by measuring width of starter ring gear plus
dimension from forward machined surface of ring gear to forward edge of compressor drive belt-
(Refer to figure 21-11.)
c. Check and adjust compressor and alternator drive belts as required. Refer to following appropriate
instructions.
6. Compressor Belt Alignment: (Refer to figure 21-11.)
a. Place straightedge against right forward side of ring gear and measure belt alignment at
compressor sheave (point B).
b. Measure belt alignment at compressor idler pulley (point A). Belt misalignment at point A should
be half misalignment of point B and dimension at top of ring gear and in same direction fore and
aft.
c. If at point A nominal misalignment is not within +/- 0,030 of an inch, as obtained from step b, add
or remove shims as required. Belt alignment should be made as close to nominal as shims will
allow.
7. Alternator Belt Alignment: (Refer to figure 21-11.)
a. With alternator belt installed, align idler pulley in belt plane by adding or removing shims, P/N
62833-82 as required.
ADJUSTMENT OF DRIVE BELT TENSION
Adjustment of compressor or alternator drive belts is very important to obtain long belt life and proper
component operation.
1. For adjustment of Deco belts, proceed with following steps. For adjustment of Gates belts, proceed to
step 2.
a. Adjust new compressor belt to 120 pounds span tension and new alternator belt to 90 to 100
pounds span tension. Use a calibrated belt tension gauge.
—CAUTION—
Higher tension specified for a new belt is to compensate for
initial stretch that takes place as soon as it is operated Higher
tension values must not be applied to belts which previously have
been used. See tensions noted for used belts.
b. Install engine baffles if removed and install engine cowling.
21 - 53 - 00
Page - 21 - 29
Reissued: August 1, 1986
1G19
PIPER AIRCRAFT
PA-28-236
MAINTENANCE MANUAL
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