Fume Exhaust Fans
14
Belt Drive Maintenance
V-belt drives must be checked on a regular basis
for wear, tension, alignment and dirt accumulation.
Premature or frequent belt failures can be caused by
improper belt tension (either too loose or too tight)
or misaligned sheaves. Abnormally high belt tension
or drive misalignment will cause excessive bearing
loads and may result in failure of the fan and/or motor
bearings. Conversely, loose belts will cause squealing
on start-up, excessive belt flutter, slippage and
overheated sheaves. Either excessively loose or tight
belts may cause fan vibration.
When replacing V-belts on multiple groove drives all
belts should be changed to provide uniform drive
loading. Use a set of matched belts whenever possible.
Do not pry belts on or off the sheave. Loosen belt
tension until belts can be removed by simply lifting the
belts off the sheaves. After replacing belts, ensure that
slack in each belt is on the same side of the drive. Belt
dressing should never be used.
Do not install new belts on worn sheaves. If the sheaves
have grooves worn in them, they must be replaced
before new belts are installed.
The proper tension for operating a V-belt drive is
the lowest tension at which the belts will not slip at
peak load conditions. Belts are adjusted by raising or
lowering the motor
pivot plate. For
initial tensioning,
the proper
belt deflection
halfway between
sheave centers is
1/64-inch for each
inch of belt span.
Check belt tension two times during the first
24 hours of operation and periodically thereafter.
Variable Frequency Drive Operation
For operation with variable frequency drive (VFD),
always check motor amps when adjusting the operating
frequency. Motor may be sized for the original selected
operating speed under 60 Hz. Bypassing the VFD or
increasing the speed from this original selection, even if
less than 60 Hz, may cause motor to overload or failure.
Consult factory with fan serial number, before increasing
the upper limiting frequency.
Always check the fan rpm when adjusting the operating
frequency. Do not exceed maximum class fan rpm of
the wheel.
Belt Span
Deflection =
Belt Span
64
Recommended Bearing Lubrication Schedule
Relubrication Schedule in Months
Standard Grease
Fan
RPM
Bearing Bore (inches)
1/2 -1
1
1
⁄
8
- 1
1
⁄
2
1
5
⁄
8
- 1
7
⁄
8
1
15
⁄
16
- 2
3
⁄
16
2
7
⁄
16
- 3
To 250
12
12
12
12
12
500
12
12
11
10
8
750
12
9
8
7
6
1000
12
7
6
5
4
1250
12
6
5
4
3
1500
12
5
4
3
2
2000
12
3
3
2
1
2500
12
2
2
1
0.5
3000
12
2
1
0.5
0.25
3500
12
1
0.5
0.25
x
4000
12
0.5
0.25
x
x
5000
12
0.25
x
x
x
Number
of Shots
4
8
8
10
16
Bearing Lubrication Schedule
Shaft bearings are the most critical moving part of a
fan. Therefore, special attention should be given to
keeping the bearings clean and well lubricated. Proper
lubrication provides for reduction in friction and wear,
transmission and dissipation of heat, extended bearing
life and prevention of rust.
In order for a lubricant to fulfill these tasks, the proper
grease applied at regular intervals is required. See the
recommended bearing lubrication schedule below.
If unusual conditions exist (temperatures below 32°F or
above 200°F), moisture or contaminants - more frequent
lubrication is required.
• Lubrication interval is based on 12 hour per day operation
and maximum 160°F housing temperature. For 24 hour per
day operation, the interval should be cut in half.
• Lubricant should be added with the shaft rotating and
until clean grease is seen purging from the bearing.
The lubrication interval may be modified based on the
condition of the purged grease. If bearing is not visible to
observe purged grease, lubricate with number of shots
indicated in chart for bore size.
• For conditions including high temperatures, moisture, dirt
or excessive vibration, consult the factory for a specific
lubrication interval for your application.
• Lubricant should be a high quality lithium complex grease
conforming to NLGI Grade 2. Factory recommends
Mobilux EP-2.
• The use of synthetic lubricants will increase lubrication
intervals by approximately 3 times.
In addition to lubricating the bearings at specified
intervals, set screws in the bearing collars should be
checked for tightness. A bearing collar which has
loosened will cause premature failure of the fan shaft.
Fasteners attaching the bearings to the drive frame
should also be checked.
