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Failed
Wheel Bearing
A tractor trailer's front wheel separated from the
axle, traveled across the median and struck an
oncoming vehicle, resulting in a fatality. A
metallurgical failure analysis was requested on the
truck's front axle, several wheel bearings, the left
front wheel hub, brake drum and brake shoe. The
failure analysis included a visual inspection only.
After examination the possible causes of the bearing
failure were addressed:
1. Improper wheel bearing installation - The truck traveled
a small number of miles since bearing
installation.
2. Improper/Inadequate lubrication - The testimony of the driver
also supported the theory that wheel bearing
lubrication was properly maintained and inspected.
3. Latent product defect - The driver testified he
neither heard nor felt anything unusual prior to the
incident, indicating the bearing failure was a
sudden and unexpected event. A latent defect in the
subject bearing could have increased in size
propagating by metal fatigue.
Failure of the subject bearing and loss of the left
front steering axle wheel was most probably the
result of a latent defect in the subject front axle
wheel bearing.
Photograph A:
Close-up view of failed
wheel bearing
showing lack of lubrication.
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Dr.
R. Craig Jerner, Ph.D., PE specializes in accident
investigation and metallurgical failure analysis,
with over 30 years experience as a metallurgical
consultant and accident investigator. He has
testified as a metallurgical expert in over 250
depositions and more than 70 court appearances. If you or someone you know should need the services of Dr. Jerner and J.E.I. Metallurgical, please visit our web site at the buttons below, or e-mail Dr. Jerner --- 