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General Information
Belt Sheave Alignment
FIG. 34: Check the sheave and shaft alignment.
Running the belts with the sheaves out of alignment will
cause severe side wear.
Not aligned belt drives will be noisier than properly
aligned drives since interference is at the belts enter point
into the sheave.
To check the alignment use a long straight edge (1) made
of wood, metal, or any rigid material. Line the straight
edge along the outside face of both sheaves. If the drive is
properly aligned, the straight edge will contact each
sheave evenly. The straight edge must touch the two
outer edges of each sheave for a total of four points of
contact.
Shafts not in alignment (C) will show up as a gap (2)
between the outside face of the sheave and the straight
edge.
Check for tilting or shafts not aligned by using a bubble
level. For proper alignment, the bubble must be in the
same position as measured on each shaft.
Not aligned correctly Parallel (A).
Not aligned correctly Angular (B).
Rotate the drive and look for excessive sheave
movement. If excessive sheave movement is seen
inspect the sheave and shaft. If no problem can be seen,
remove and install the sheave. Not correctly mounted
sheaves or out of round sheaves are some times the root
of vibration or more severe problems. A dial indicator can
be used to measure side to side sheave movement or
diameter vibration by holding the dial indicator up to the
sheave sidewall or top of the belt inside the pulley groove.
IMPORTANT: Always turn off the machine before using
the dial indicator. Rotate the drive by hand to
make your measurements.
Belt Run In Procedure
A run in procedure is needed for all belt drives so that the
best belt life can be reached.
A run in procedure is made of starting the drive and
operating the drive under full load for up to 24 hours. After
the belts have run-in, stop the drive and check the belt
tension.
Running the belts under full load for an extended period of
time will seat the belts into the sheave grooves.
Belt tension will drop after the first run-in and seating
procedure. This is normal. Adjust the belt tension as
necessary.
Since tension in the belts will drop after the first run-in and
seating procedure, failure to check and tension the belt
will result in low belt tension and belt slippage. This
slippage will result in early belt failure.
01-26
B
A
FIG. 34
2
C
1
D-5595c
4283528M1
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