Motor Sheave Adjustments - Daikin DCC Series Installation Instructions Manual

b C
earing HeCk
Prior to energizing any fans, check and make sure that all
setscrews are tight so that bearings are properly secured
to shafts.
For heat pump units, the airflow must be adjusted so that the
air temperature rise falls within the ranges given stated on
Data Plate (see Appendix A - Blower Performance).
t a
ensiOn anD lignment
Correct belt tension is very important to the life of your belt.
Too loose a belt will shorten its life; too tight, premature motor
and bearing failure will occur. Check you belt drive for ade-
quate "run-in" belt tension by measuring the force required
to deflect the belt at the midpoint of the span length. Belt
tension force can be measured using a belt tension gauge,
available through most belt drive manufacturers.
D
*Apply force to the center of the span.
t = Span length, inches
C = Center distance, inches
D = Larger sheave diameter, inches
d = Smaller sheave diameter, inches
h = Deflection height, inches
a
Djustment
C
DRIVE BELT TENSION ADJUSTMENT
TYPE
MODEL
BELT DRIVE
7.5 Ton
8.5 Ton
A, AX Standard
10 Ton
12.5 Ton
RECOMMENDED POUNDS OF FORCE PER BELT
When new V-belts are installed on a drive, the initial tension
will drop rapidly during the first few hours of use. Check
tension frequently during the first 24 hours of operation.
Subsequent retentioning should fall between the minimum
and maximum force. To determine the deflection distance
from a normal position, use a straightedge or stretch a cord
from sheave to sheave to use as a reference line. On mul-
tiple belt drives, an adjacent undeflected belt can be used
as a reference.

MOTOR SHEAVE ADJUSTMENTS

v , v & 2 v
l m vP ariable
The driving and driven motor sheaves should be in alignment
with each other and the shafts parallel.
v & v s a
l m Heaves
1. Loosen set screw "B" using a 5/32" Allen key.
2. Making half or full turns from closed position, adjust
sheave pitch diameter for desired speed. DO NOT
OPEN MORE THAN FIVE FULL TURNS.
3. Tighten set screw "B" securely over flat.
4. Carefully put on belts and adjust belt tension. DO
NOT FORCE BELTS OVER GROOVES.
5. Ensure all keys are in place and the set screws tight
before starting drive. Recheck set screws and belt
tension after 24 hours service.
NOTE: Future adjustments should be made by loosening the
belt tension and increasing or decreasing the pitch diameter
of the sheave by half or full turns as required. Readjust belt
tension before starting drive.
12
DEFLECTION
SHEAVE
FORCE (lbs)
DIAMETE
R (in)
Used New
2.6 to 3.6 3.75 +/- 0.5 4.0 +/- 0.5 9/32 +/- 1/16
2.6 to 3.6 3.75 +/- 0.5 4.0 +/- 0.5 9/32 +/- 1/16
3.0 to 4.0 3.75 +/- 0.5 4.0 +/- 0.5 9/32 +/- 1/16
2.6 to 3.6 3.75 +/- 0.5 4.0 +/- 0.5 9/32 +/- 1/16
P k t m
itCH ey yPe OtOr
Djustment
DEFLECTION
(in)
s
Heaves