JOHNSON CONTROLS
8
MAINTENANCE (CONTINUED)
Base your particular interval on condition of grease after a
specific service period.The chart below is intended as a guideline
for your consideration. (Figure 1)
Belt Drives
Fans shipped completely assembled have had the belt drive
aligned at the factory. Alignment must be checked before
operation.
1. Be sure shelves are locked in position.
2. Key should be seated firmly in keyway.
3. The motor and fan shafts must be properly aligned, with the
center line of the belts at a right angle to the shafts.
4. Start the fan. Check for proper rotation of impeller. Run
fan at full speed. A slight belt bow should appear on the
slack side. Adjust belt tension by adjusting motor on its
adjustable base.
5. If belts squeal excessively at start up, they are too loose and
should be tightened.
6. When belts have had time to seat in the sheave grooves,
readjust belt tension. Check belt tension after 8, 24 and 100
hours of operation.
Belt Drive Assembly can be Mounted as Follows:
1. Clean motor and drive shafts. Be sure they are free from
corrosive material. Clean bore of sheaves and coat with
heavy oil for ease of shaft entry. Remove oil, grease, rust or
burrs from sheaves. Place fan sheave on fan shaft and motor
sheave on its shaft. DO NOT POUND ON sheave as it may
result in damage. Tighten sheaves in place.
2. Move motor on base so belts can be placed in grooves of
both sheaves without forcing. Do not roll belts or use tool
to force belts over grooves.
3. Align fan andmotor shafts so they are parallel. The belts
should be at right angles to the shafts. A straight edge or
taut cord placed across the faces of the sheaves will aid in
alignment with single groove sheaves. If multiple groove
sheaves are installed, use the center line of the drive as your
alignment point.
4. Tighten belts by sliding motor in its base. Correct tension
gives the best efficiency. Excessive tension causes undue
bearing pressure.
5. Be sure all safety guards are in place.
6. Start the fan and run at full speed. Adjust belt tension until
only a slight bow appears on the slack side of the belts. If
slippage occurs, a squeal will be heard at start up. Eliminate
the squeal by tightening the belts.
7. Belts require time to become fully seated in the sheave
grooves. Check belt tension after 8, 24 and 100 hours of
operation. Allowing belts to operate with improper tension
will shorten belt life substantially.
8. If the shafts become scratched or marked, carefully remove
the sharp edges and high spots such as burrs with fine emery
cloth or a honing stone. Avoid getting emery dust in the
bearings.
9. Do not apply any belt dressing unless it is recommended
by the drive manufacturer. Belts are designed for frictional
contact between the grooves and sides of the belts. Dressing
will reduce this friction.
10. Minimum belt center distances are available from factory
upon request.
11. Belt tension on an adjustable pitch drive is obtained by
moving the motor, not by changing the pitch diameter of
the adjustable sheaves.
Shaft
Size
Operating Speed (RPM)
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
Lubrication Frequency (Months)
.50”-1.00”
6
6
6
6
6
6
4
4
2
2
1.06”-1.44”
6
6
6
6
6
6
4
4
2
1
1.50”-1.75”
6
6
6
4
4
2
2
2
1
1
1.88”-2.19”
6
6
4
4
2
2
1
1
1
2.25”-2.44”
6
4
4
2
2
1
1
1
2.50”-3.00”
6
4
4
2
1
1
1
3.06”-3.50”
6
4
2
1
1
1
3.56”-4.00”
6
4
2
1
1
FIGURE 1: FREQUENCY OF LUBRICATION