8 Care and Maintenance of Bearings
8.1 Bearing temperatures
All bearings operate at some temperature above that of the surrounding atmosphere, unless cooled.
Heat is generated within the bearing due to rolling friction, churning of oil and the "drag" of the race.
Do not use the human hand as a thermometer. A temperature which feels "hot" varies from 120°F -
130°F depending upon the individual. Above this temperature, the human hand is worthless in estimating
temperature.
Bearing temperatures up to 180°F are normal. Deter mine the temperature accurately by placing a con-
tact type thermometer against the bearing housing. It should be recorded in a convenient location for ref-
erence. The stability of the temperature, rather than the number of degrees, is the best indication of nor-
mal operation. A sudden increase in temperature is an indication of danger and a signal to investigate.
The unit should be checked for abnormal hydraulic operation and unnecessary loads, such as coupling
misalignment, etc.
8.2 Bearing inspection
1.
Ball and Roller Bearings
Ball and roller bearings can be checked for visible wear by slowly turning the races and watching
for pits or worn areas on the balls, rollers or raceways. The bearings can also be inspected by
holding the inner race and spinning the outer race. If any rasping noises are emitted or the bear-
ing "catches", it should be replaced. If any wear on the races is apparent, replacement is sug-
gested.
2.
Sleeve Bearings
Sleeve bearings should be inspected to determine if any deep scratches or gouges (other than oil
grooves) are present. The babbitted surfaces should also be free of high or low spots. Unless
these surfaces are completely smooth, they should be replaced if they cannot be ''scraped in.''
8.3 Cleaning of bearings
The life of a bearing can be drastically reduced if contaminated with even a small amount of dust or dirt.
All bearing assembly operations should be done in as dust-free an atmosphere as possible. All tools, as
well as the hands, should be kept clean.
If new bearings are to be installed, they should not be unwrapped until ready for installation and should
not be cleaned or washed.
If old bearings are dirty, they should be replaced. Washing the bearings does not guarantee cleanliness
and is risky at best. If new bearings are not readily available, and immediate reassembly is necessary,
dirty bearings can be cleaned as follows:
Pour one or two quarts of clean, water free kerosene into a clean pail. Dip the bearings into the kerosene
and agitate slowly. Repeat until bearing is completely clean. Blow dry with clean filtered compressed air.
With ball bearings, hold the two races together, but allow the inner race to rotate a few turns now and
then to dislodge the kerosene from the retainer pockets. When the bearing has been blown dry, oil it im-
mediately with a good grade of clean machine oil to prevent corrosion or rust.
If there is any question as to the condition of bearings, it is always best to replace them. This may pre-
vent an unplanned shutdown.
8 Care and Maintenance of Bearings
50
3107 Installation, Operation and Maintenance Instructions
