Page 345 - Practical Machinery Management for Process Plants Major Process Equipment Maintenance and Repair

Installation and Maintenance of VBelt Drives 325

Tenslonlng by General Method
The general method for tensioning V-belts should satisfy most drive re-
quirements :
Step 1 Reduce the center distance so that the belts may be placed over
the sheaves and in the grooves without forcing them over the
sides of the grooves. Arrange the belts so that both the top and
bottom spans have about the same sag. Apply tension to the belts
by increasing the center distance until the belts are snug. See Fig-
UR 7-13.
Step 2 Operate the drive a few minutes to seat the belts in the sheave
grooves. Observe the operation of the drive under it3 highest
load condition (usually starting). A slight bowing of the slack
side of the drive indicates proper tension. If the slack side re-
mains taut during the peak load, the drive is too tight. Exces-
sive bowing or slippage indicates insufficient tension. If the
belts squeal as the motor comes on or at some subsequent peak
load, they are not tight enough to deliver the torque demanded
by the drive machine. The drive should be stopped and the belts
tightened.

figure 7-13. Belt tension diagram.