ball and roller bearings - NTN Bearing Corporation of

ANALYSIS OF BEARING OPERATING PROBLEMS
The following table lists some common types of bearing operating problems, probable causes,
and suggested corrective measures. If these suggestions do not correct the trouble, call your
Representative for assistance.
Trouble Observed Probable Corrective Action
Characteristic Cause
NOISE
TEMPERATURE
High pitch,
steady tone
Low pitch,
continuous or
intermittent
Intermittent
squeal or high
pitch noise
Intermittent
rumbles, rattles,
clicks, etc.
High after first
start
Continuously
high during
operation
Excessive
axial load
Excessive
radial load
Misalignment
Too much clearance
in bearing
Bearing brinelled
Raceways pitted
due to dirt
Resonant
virbration of
machine structure
Balls skidding
Shaft rubbing housing
Too much clearance
in bearing
Dirt in bearing
Loose machine
parts
Grease
redistribution
Churning of
lubricant
No lubricant
Excessive
axial load
Excessive
radial load
Bearing
misaligned
Excessive seal drag
Continued next page …
TECHNICAL
INFORMATION
Correct outer ring fit in housing and/or shoulder
location to allow thermal expansion.
Use correct fit of inner ring on shaft. For radial bearings,
use bearing with greater internal clearance. For preloaded
paired bearings, use lighter preload.
Correct alignment.
Use correct shaft fit. For radial bearings, use bearing
with less internal clearance. For preloaded paired bearings,
use heavier preload.
Replace bearing, avoid brinelling.
Wash all parts, replace with new bearing, use clean
lubricant, improve seals.
Stiffen or sound-deaden thin panels and large flat
surfaces.
Provide thrust preload spring. Use thinner grease. For
radial bearings, use bearing with less internal clearance.
For preloaded paired bearings, check for correct
preload.
Correct seals and machine parts.
Correct shaft fit. For radial bearings, use adjusting
spring or bearing with less internal clearance. For preloaded
paired bearings, check for correct preload.
Wash all parts, replace with new bearing if necessary,
use clean lubricant, improve seals.
Tighten all fans, pulleys, closures, spacers, slingers etc.
Allow machine to cool. Restart.
Use lower oil level, less grease, stiffer grease.
Add lubricant.
Check outer ring fit in housing and/or shoulder location
to allow thermal expansion.
Use correct fit of inner ring on shaft. For radial bearings,
use bearing with greater internal clearance. For preloaded
paired bearings, use lighter preload.
Correct machine parts and alignment procedures.
Use different type of seal.
243