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9. LUBRICATION - HT FANS
CAUTION!
It is necessary to record the number of hours the motor has operated in order to determine when bearing
relubrication is required. If the motor is not running continuously, the date of installation must be recorded, since
relubrication is recommended every three to six months, even if the motor has not been run during this time.
WARNING!
Beware of all rotating parts!
Grease can cause skin and eye irritation when re-greasing. Follow all safety precautions specified by the grease
manufacturer.
SHIELDED/SEALED BEARINGS
Small motors (WEG 80-132 frames or Brook 71-180 frames) which are fitted with 'sealed for life' ZZ/2Z bearings (that are pre-
greased), must be replaced after 20,000 running hours (if fans are continuously running). If the fan is a "dual mode" fan or if it is a
dedicated fire safety (smoke extract) fan, checks should take place every 6 months to determine if the fan (motor) bearings have
become noisy or appear to have become unbalanced. Check motor nameplate for determining the bearing type used.
MOTORS FITTED WITH GREASE RE-LUBRICATION POINTS
Bearing grease re-lubrication points are usually fitted to larger frame motors than those mentioned above. Regular maintenance
and adherence to re-greasing procedures will prolong bearing life. Failure to do this may shorten bearing life considerably.
Maintenance includes:
a) Attention to the overall bearing condition;
b) Cleaning and lubrication;
c) Detailed inspection of the bearings.
Although bearing problems may often be detected by listening for unusual bearing noise, more sophisticated equipment should
be used to obtain a quantified bearing condition analysis. Bearings must be lubricated to avoid metallic and direct contact of the
moving parts, and to provide protection against corrosion and wear. Lubricant properties deteriorate over time due to mechanical
operation, furthermore, all lubricants are subject to contamination under working conditions. For this reason, lubricants must be
renewed or replenished on a regular basis, in accordance with motor manufacturers recommendations.
NOTE!
Bearings with grease re-lubrication points must be replaced after 40,000 running hours or 5 years,
whichever occurs first.
LUBRICATION INTERVALS
It should be noted that some grease types may cause higher bearing noise levels particularly at low temperatures,
or when intermittent operation does not allow the running temperature to exceed +20 °C.
Please contact Woods Air Movement if the normal fan and motor operating temperature is below -5 °C.
Grease type, lubrication intervals, grease quantity used, and the bearing type and its associated component clearances, are all
indicated on the motor nameplate. Lubrication intervals are dependent on motor size, running speed, working conditions, grease
type and the ambient operating temperature. If required, please contact Woods Air Movement for further advice related to
bearing lubrication or replacement.
NOTE!
If the supplied fan and motor assembly was intended and designed) for horizontal operation but is then
operated in a vertical position (i.e. with the motor shaft in the vertically up or vertically down position),
then bearing lubrication intervals must be reduced by half (i.e. must be more frequent).
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CORRECT GREASE QUANTITY
Correct lubrication is very important to ensure that bearings operate reliably i.e. grease must be applied correctly and
in a sufficient amount. Lack of grease or excessive greasing may cause bearing damage.
CAUTION!
We recommend that one grease shot is measured in order to determine its weight, so that the number
of grease shots required, can be matched to the quantity (i.e. weight) as stated on the motor nameplate.
Excessive greasing causes overheating by increasing the resistance to free movement of its rotating parts and, in particular, by
the lubricant being compacted so that it loses its lubricating characteristic. An excessive application of grease may also cause it
to leak into the motor, contaminating the winding. Lack of grease causes overheating due to increased friction levels between
the rolling elements, outer ring and inner race, which will ultimately result in premature bearing failure.
GREASE COMPATIBILITY
Incompatibility between different grease types can cause problems.
ATTENTION
Never mix greases of different bases.
Example: lithium-based grease must never be mixed with sodium or calcium-based grease.
ATTENTION
To avoid any eventual grease incompatibility, always re-grease bearings with the grease type indicated
on the motor nameplate.
As a general rule, greases with the same specification are compatible, however this is dependent on the formula.
Before mixing grease types, therefore, please consult the grease supplier.
DRIVE END AND NON-DRIVE END BEARING RELUBRICATION STEPS
1. Before lubricating the bearing, clean the area around the grease re-lubrication points with clean cotton cloth;
2. With the motor running, add the amount of grease indicated on the bearing nameplate;
3. Leave the motor running for sufficient time to spread the grease on the bearing;
4. Check bearing temperature to make sure there is no significant variation.
NOTE!
On first start of the equipment or after a bearing re-lubrication, there may be a slight temperature rise for
the initial 10-20 hours of running.
If the motor cannot be lubricated while it is running under normal conditions, lubrication can be carried out as detailed below:
1. Inject about half amount of required grease, and run the motor at full speed for 5 minutes;
2. Switch off the motor and inject the remaining grease;
3. Start the motor again to ensure that grease is correctly distributed within the bearing.
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