YORK INTERNATIONAL
36
Some units may require special con-
struction considerations. YORK re-
serves the right to modify construction
of any units as deemed necessary.
SAFETY CHECK - “WARNING”
Be sure all door latches are secured before starting
unit.
MOTORS
Do not operate fan motors in overload
amperage condition.
Motor amperage should be checked again after the
connecting duct work is installed and an air check made
on the air distribution system. Only in those cases where
the air flow at the outlets is insufficient to meet specifi-
cations should the blower speed be changed. If the air
flow is sufficient at the outlets, do not alter blower speed
to bring the motor HP up to nameplate rating.
BELTS
Belts should be checked for correct tension at startup
and should be checked again after 24 hours of opera-
tion. On multiple belt adjustable pulleys, the pitch depth
should be checked to insure identical belt travel, power
transfer and wear. Adjustable motor bases are provided
for belt adjustment. See Maintenance Section.
SHEAVES AND DRIVES
Motor pulleys (both adjustable pitch
and fixed pitch, and blower shaft pul-
leys) are locked in position with ei-
ther set screws and split taper lock
bushings. All set screws and/or taper
lock bolts must be checked for tight-
ness and alignment before putting
equipment into operation.
All drive belts must also be checked for proper tension.
See section Belt Adjustment.
An incorrectly aligned and tensioned
belt can substantially shorten belt life,
or overload blower and motor bearings
shortening their life expectancy. A belt
tensioned too tightly can overload the
motor electrically, causing nuisance
tripping of the motor overloads and/
or motor failure and/or shaft failure.
LOCKING RING VARIABLE PITCH SHEAVES
(See Figure 40)
This type of sheaves consists of two flanges (1) fitted
on a threaded hub (2). (In the two-groove sheave this
threaded hub is a combined hub and center flange, as
shown in Figure 40, where as in the single flange sheave
there is no center flange.)
To adjust the pitch diameter turn flanges (1) an equal
number of turns. Malleable locking rings (3) are as-
sembled by means of cap screws and lockwashers (4)
and are correctly threaded to allow a small gap be-
tween the locking rings and flanges.
Sheave adjustment is made on one-quarter turn incre-
ments through the use of the keyway (5) on the outside
of hub (2) and four keyways in the flanges. A key (6) is
inserted through the assembly and held in place with a
setscrew (7). The locking ring cap screws (4) are tight-
ened on BOTH sides to lock the entire sheave into a
rigid unit.
Subsequent adjustments can be made by loosening the
locking ring cap screws (4) (
WARNING - Do not re-
move these cap screws
), and loosening the setscrews
(7) over key (6). The key can then be tightened and
adjustment made. Be sure to replace key and tighten
set screws and BOTH cap screws (4) before using.
FIG. 40 –
LOCKING RING VARIABLE PITCH
SHEAVES
LD06351
Operation
