Page 113 - Rotating Machinery Pratical Solutions to Unbalance and Misalignment

Misalignment of Machine Shafts

is adjusted to the rpm of the belts, and the different speeds of the
belts can be seen.
As an alternate method, operate the unit for a very short time
(bump the motor) and inspect the location of the marks on the
belts. If they have departed from each other, check for possible
misalignment. Figures 7-6 and 7-7, show exaggerated misalign-
ment in V-belt drives.
The amount of misalignment shown in Figure 7-6 would re-
sult in the drive belts being thrown off the pulleys. However, it
can be seen from the figures that misalignment can result in vibra-
tion characteristics similar to misalignment in shafts.
Too often, it is thought that belt drives are self-aligning and
thus little to no attention is paid to their alignment. This is simply

Figure 7-6. Angular Misalignment in Belt Drives.

Figure 7-7. Offset Misalignment in Belt Drives