Vibration sensors and temperature sensors can
be used to monitor bearing conditions.
Water cooled bearings should be pressure
tested for leaks before installation. Special attention should be
paid to casting plug leaks. Water leaking into lubrication systems
will float the oil; the bearing will then be running in water.
Bearings too lightly loaded experience oil
whip which is seen as violent shaft vibration. This is aggravated
by cold oil temperature or oil that is too heavy. This problem can
be eliminated by reducing bearing area and using oil at the proper
temperature and viscosity.
In general, heavy oils are used for heavy
loading and lighter oils are used for faster speeds.
For slinger ring type lubrication, peripheral
speed and oil viscosity must be correct.
Misalignment of the shaft and bearing should
be under .0003 inch per inch of bearing length.
Brinell Hardness of the shaft should be at
least 100 points harder than the bearing material for good
compatibility.
Usually if there is lack of bond between the Babbitt
and housing it can be seen at the horizontal joint of the bearing.
Electrical conduction across the bearing can
destroy the Babbitt by electrolysis.
Babbitt bearings should be inspected whenever
an opportunity presents itself and always in outages
When in doubt, ask American
Power Serviceto inspect and ultrasonically test the
bearing for integrity.