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14
5.3 Belts
Prior to startup of this machine it is recommended that the drive belt tension be checked for proper run in
deflection force as shown in illustration. After the equipment has run between 24 and 48 hours, drive belt
tension must again be checked for proper operational deflection.
A V-belt drive will successfully transmit its rated capacity if the belts are properly tensioned. The method of
tensioning is explained here in detail.
1.
Verify that the alignment of the pulleys is correct.
Utilizing a straightedge of sufficient length to
span from one pulley to the other, place it along
the sides of both pulleys. The entire edge of each
pulley should fully contact the straightedge.
2.
Measure the belt span (see figure on right).
3.
Using a spring scale, apply a perpendicular force
to any ONE of the belts at the mid-point of the
span.
4.
Measure the force (lbs.) required to deflect
any one of the belts 1/64th of an inch for every inch of span. For example: the deflection for a 32 inch span
would be 1/64th of an inch times 32 or 1/2 of an inch.
5.
The motor position should be adjusted until the actual deflection force matches the distance of deflection
referenced in step 4 above.
6.
There will normally be a drop in the belt tension during the first 24 to 48 hours of operation due to belts
stretching and the belts seating themselves in the sheave grooves.
7.
After this initial run in period, the machine should be stopped, and the belts should be rechecked for
tension. The motor position should be adjusted until the deflection force matches the values in column B.
8.
Over-tensioning the belts can significantly reduce belt and bearing life.
