QT/QTS Series
Quincy Compressor
2022208700, September 2018
38
Pulley / Sheave Alignment & Belt Tension
Improper pulley/sheave alignment and belt tension are causes for mo tor
overloading, excessive vibration, and premature belt and/or bearing failure.
To prevent this from happening, check the pulley/sheave alignment and belt
tension on a regular basis (refer to
SECTION 5,
Maintenance Schedule
).
Periodically inspect the motor pulley(s) and compressor sheave(s) for oil,
grease, nicks or burrs. Clean or replace if necessary. Make sure they are securely
fastened. Align the compressor sheave with the motor or engine pulley. Drive
belt grooves of the pulley(s) and sheave(s) should be in line with each other.
The compressor crankshaft must be parallel to the motor or engine drive shaft.
Belt tension should be measured and adjusted to provide smooth op eration.
Step-by-step procedures are provided here to correctly measure and set the
drive belt tension:
Step 1)
Measure the span length of the drive. (Refer to
Fig. 5-1, Setting
Belt Tension
.)
Belt
Motor Pulley
Recommended
Cross
Dia. Range
Deflection Force (lbs.)
Section (inches) Minimum Maximum
A
QTS-3, QTS-5 & QT-54
2
3
B 4.6 4.0 5.9
B
5.0 - 5.4
4.5
6.7
B
5.6 - 6.4
5.0
7.4
B
6.8 - 9.4
5.8
8.6
Step 2)
Determine the amount of deflection ( in inches) required to measure
de flection force (in pounds) by multi plying the span length x
1
/
64
(.016) (i.e. 32” span length x
1
/
64
[.016] =
1
/
2
”[.50] of deflection required
to measure de flection force).
Fig. 5-1
Setting Belt Tension