Installation manual
Page 76 IM-487
Figure 73. Sheave Alignment (adjustable shown)
Drive Belt Adjustment
General Rules of Tensioning
1. The ideal tension is the lowest tension at which the belt
will not slip under peak load conditions.
2. Check tension frequently during the first 24-48 hours of
operation.
3. Over tensioning shortens belt and bearing life.
4. Keep belts free from foreign material which may cause
slippage.
5. Make V-drive inspection on a periodic basis. Adjust ten-
sion if the belt is slipping. Do not apply belt dressing. This
may damage the belt and cause early failure.
Tension Measurement Procedure
1. Measure the belt span. See Figure 74.
2. Place belt tension checker squarely on one belt at the cen-
ter of the belt span. Apply force to the checker, perpendic-
ular to the belt span, until the belt deflection equals belt
span distance divided by 64. Determine force applied
while in this position.
3. Compare this force to the values in Table 15 on page 76.
Figure 74. Drive Belt Adjustment
Table 15: Belt Deflection Force (not applicable for Exhaust Fans - see “Belts” on page 70
)
C e n t e r l i n e s
m u s t c o i n c i d
e
M u s t b e
p a r a l l e l
M u s t b e
p a r a l l e l
A d j u s t a b l e
S h e a v e
M o t o r
B e a r i n g
B e l t S p a n
D e f l e c t i o n =
B e l t S p a n
6 4
CROSS SECTION
SHEAVE DIAMETER (INCHES) DEFELCTION FORCE (LBS.)
SMALLEST SHEAVE
DIAMETER RANGE
RPM RANGE
BELT DEFLECTION FORCE
CROSS SECTION A, B, 5V CROSS SECTION AX, BX, 5VX
USED BELT NEW BELT USED BELT NEW BELT
A, AX
3.0-3.6
1000-2500 3.7 5.5 4.1 6.1
2501-4000 2.8 4.2 3.4 5.0
3.8-4.8
1000-2500 4.5 6.8 5.0 7.4
2501-4000 3.8 5.7 4.3 6.4
5.0-7.0
1000-2500 5.4 8.0 5.7 9.4
2501-4000 4.7 7.0 5.1 7.6
B, BX
3.4-4.2
850-2500 — — 4.9 7.2
2501-4000 — — 4.2 6.2
4.4-5.6
860-2500 5.3 7.9 7.1 10.5
2501-4000 4.5 6.7 7.1 9.1
5.8-8.6
860-2500 6.3 9.4 8.5 12.6
2501-4000 6.0 8.9 7.3 10.9
5V, 5VX
4.4-6.7
500-1749 — — 10.2 15.2
1750-3000 — — 8.8 13.2
3001-4000 — — 5.6 8.5
7.1-10.9
500-1740 12.7 18.9 14.8 22.1
1741-3000 11.2 16.7 13.7 20.1
11.8-16.0
500-1740 15.5 23.4 17.1 25.5
1741-3000 14.6 21.8 16.8 25.0