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KAH Operation & Maintenance Guide
Page: 40 of 88
SECTION 3 - MAINTENANCE (CONTINUED)
ALIGNING SHEAVES
CAUTION -
An incorrectly aligned sheave can substantially shorten belt life or overload blower and motor
bearings, shortening their life expectancy. A belt tensioned too tightly can overload the motor electrically,
causing nuisance tripping of the motor overloads and/or motor failure and/or shaft failure.
FIGURE 39 - ALIGNMENT USING STRAIGHT EDGE
Straight Edge Touching Sheaves At Points Indicated By Arrows
ALIGNMENT USING STRAIGHT EDGE
FIGURE 40 - ALIGNMENT USING STRING
Cord Touching Sheaves At points Indicated By Arrows
ALIGNMENT USING STRING
Cord Tied To Shaft
Sheave alignment and parallelism
of shafts is very important. Proper
alignment helps equalize the load across
the entire belt width, thereby reducing
wear and extending belt life. Figure 39
(right) shows how to align a synchronous
drive properly using a straightedge or
shows how to use a piece of string as
shown in Figure 40 (right).
After aligning the sheaves, check the
rigidity of the supporting framework.
Shafts should be well supported to
prevent distortion and a resulting change
in the center distance under load. Do not
use spring-loaded or weighted idlers.
Using a Straightedge
Place a straightedge against the outer
edge of the sheaves. Figure 39 (right)
shows the four points where the straight
edge should touch the sheaves. The
straight edge should cross the sheaves
at the widest possible part of the sheave.
Using a String
Tie a string around either shaft and pull it
around and across the outer edge of both
sheaves as shown in Figure 40 (right)
shows how the string should touch four
points when the drive is properly aligned.
If alignment is different than described,
refer to Sheave Replacement and
Adjustment later in this section.
