Daikin DCH048 SERIES, Service Instructions Manual

Page: 127 / 139

SERVICING
32
between the minimum and maximum force. To determine the
deflection distance from the normal position, use a straight-
edge or stretch a cord from sheave to sheave to use as a
reference line. On multiple belt drives, an adjacent undeflected
belt can be used as a reference.
SPAN LENGTH t
*DEFLECTION
FORCE
h
C
d H
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
DRIVE BELT TENSION ADJUSTMENT
15&20 TON MODELS
MODEL
SHEAVE
DIAMETER
(in)
DEFLECTION
(in)
BELT DRIVE Used New
15 Ton B, BA Standard 4.3 to 5.5 5.5 + .5 8.2 + .5 1/4 ± 1/16
20 Ton
25 Ton
B, BA Standard 4.3 to 5.5 5.5 + .5 8.2 + .5 1/4 ± 1/16
DEFLECTION
FORCE (lbs)
TYPE
RECOMMENDED POUNDS OF FORCE PER BELT
S-206 INDOOR FAN ROTATION CHECK
Evaporator Fan Rotation Check (Three Phase Models
Only)
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,
repeat bearing check.
Do not attempt to change load side wiring. Internal wiring
assures all motors and compressors will rotate in correct
direction once evaporator fan motor rotation check has been
made.
S-207 MOTOR SHEAVE ADJUSTMENTS
V
L
, V
M
& 2
VP
V
ARIABLE
P
ITCH
K
EY
T
YPE
M
OTOR
S
HEAVES
The driving and driven motor sheaves should be in alignment
with each other and the shafts parallel.
V
L
& V
M
S
HEAVES
A
DJUSTMENT
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 SIX 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.
C
B
VL & VM
NOTE: Do not operate sheave with flange projecting
beyond the hub end.