Motor Sheave Adjustments - Daikin DSG Series Installation Instructions Manual

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vaPOratOr an OtatiOn
Check that fan rotates clockwise when viewed from the drive
side of unit and in accordance with rotation arrow shown
on blower housing. If it does not, reverse any two incoming
power cables at Single Point Power Block. In this case, re-
peat bearing check.
Do not attempt to change load side wiring. Internal wiring
assures all motors and compressors will rotate in correct di-
rection once evaporator fan motor rotation check has been
made.
e i c
lectrical nPut heck
Make preliminary check of evaporator fan ampere draw and
verify that motor nameplate amps are not exceeded. A final
check of amp draw should be made upon completion of air
balancing of the duct system (see Appendix B).
BELT DRIVE MODELS ONLY
The drive on the supply fan is typically set in the middle
of the RPM range. The drive motor sheave pitch diameter
is field adjustable for the required airflow. Refer to "Motor
Sheave Adjustments" section.
Upon completion of the air flow balancing, we recommend
replacing the variable pitched motor sheave with a proper-
ly-sized fixed sheave. A matching fixed sheave will provide
longer belt and bearing life and vibration free operation. Ini-
tially, it is best to have a variable pitched motor sheave for
the purpose of airflow balancing, but once the balance has
been achieved, fixed sheaves maintain alignment and min-
imize vibration more effectively. For direct drive units, move
fan speed wire.
b c
earing heck
Prior to energizing any fans, check and make sure that all set-
screws are tight so that bearings are properly secured to shafts.
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 mo-
tor and bearing failure will occur. Check you belt drive for ad-
equate "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.
c (t P m
heck hree hase Odels
a
djustment
O )
nly
*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
TYPE
BELT DRIVE
AX Standard
Recommended Pounds of Force Per Belt
New V-belts will drop rapidly during the first few hours of
use. Check tension frequently during the first 24 hours of op-
eration. Tension should fall between the minimum and maxi-
mum force. To determine the deflection distance from a nor-
mal position, measure the distance from sheave to sheave
using a straightedge or a cord. This is your reference line.
On multiple belt drives, an adjacent undeflected belt can be
used as a reference.

MOTOR SHEAVE ADJUSTMENTS

v , v , & 2 v
l m vP
The driving and driven motor sheaves should be in align-
ment with each other and the shafts parallel.
v & v s
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 be-
fore 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 diam-
eter of the sheave by half or full turns as required. Readjust
belt tension before starting drive.
16
D
C
Belt Tension Adjustment
SMALL
DEFLECTION
SHEAVE
FORCE (lbs)
DIAMETER
(in)
USED NEW
3.0 to 4.0 4.2 ± 0.5 5.5 ± 0.5
P k t
ariable itch ey yPe
a
djustment
DEFLECTION
(in)
0.313
m s
OtOr heaves