USC AT500H Quick Start Manual page 4

V-Belt tensioning adjustment can be made using a tension meter or other type spring
scale using the following procedure. After seating the belts in the groove and adjusting
center distance so as to take up the slack in the belts, further increase the tension until
only a slight bow on the slack side is apparent while the drive is operating under load.
Stop the drive and using the meter, measure the force necessary to depress one of the
center belts 1/64 inch for every inch of belt span (see sketch below). For example, a
deflection for a 50 inch belt span is 50/64 or 25/32 inch. The amount of force required
to deflect the belt should compare with the deflection forces noted in the table below.
Also notice for V- Belts that deflection forces vary from the initial RUN - IN values
which are greater (reflecting higher run-in tensioning) to the NORMAL values for after
the run-in period.
BELT
CROSS SECTION
AX
BX
Page 4
BELT TENSIONING SPECIFICATION
SMALLER PULLEY
DIAMETER RANGE
(inches)
3.0 - 3.6
3.8 - 4.8
5.0 - 7.0
3.4 - 4.2
4.4 - 5.2
5.4 - 9.4
DEFLECTION FORCE
RUN - IN (lbs) NORMAL (lbs)
4 - 1/8
5
6
5 - 1/4
7 - 1/8
9
2 - 3/4
3 - 1/4
4
3 - 1/2
4 - 3/4
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