How to Identify Tapered Roller Bearing Damage

Skill Level: Easy | Special Tools: None

Recognizing causes and types of bearing damage can help you prevent further bearing damage resulting in improved bearing life and performance.

Fatigue Spalling

Geometric stress concentration (GSC)

Geometric stress concentration (GSC):
Misalignment, system deflections and heavy loading.

Point surface origin (PSO)

Point surface origin (PSO):
Debris and raised metal exceeding the lubricant film thickness.

Inclusion origin

Inclusion origin:
Oxides or other hard inclusions in bearing steel.

Deformation

Bearing cone (inner race) large rib face deformation

Bearing cone (inner race) large rib face deformation:
Metal flow from excessive heat generation.

Total bearing lock-up bearing damage

Total bearing lock-up:
Rollers skew and slide sideways.

Handling Damage

Roller spaced nicking

Roller spaced nicking:
Raised metal on races from contact with roller edges.

Roller nicking and denting

Roller nicking and denting:
Rough handling or installation damage.

Bearing cup (outer race)-face denting

Bearing cup (outer race)-face denting:
Indentations from hardened driver.

Cage Damage

Cage deformation

Cage deformation:
Improperly installed or dropped bearing.

Rollers binding and skewing

Rollers binding and skewing:
Cage ring compressed or interfered with during installation or service.

Excessive End-Play Damage

Cage pocket wear

Cage pocket wear:
Heavy contact between rollers and cage pocket surfaces caused by bearing operating
too loosely.

Scalloping

Scalloping:
Uneven localized wear resulting from excessive end-play.

Excessive Preload or Overload Damage

Bearing cone (inner race) bore polishing

Bearing cone (inner race) bore polishing:
Contact wear and creeping on shaft caused by lack of lubrication and cone bore
contraction from excessively tight setting (preload).
* Damage caused by excessive preload can appear similar to damage caused by
inadequate lubrication.

Full race width fatigue spalling

Full race width fatigue spalling:
Caused by heavy loads creating a thin lubricant film and elevated temperatures.

Scoring

Roller end scoring

Roller end scoring:
Metal-to-metal contact from breakdown of lubricant film.

Bearing cone (inner race) large rib face scoring

Bearing cone (inner race) large rib face scoring:
‘Welding’ and heat damage from metal-to-metal contact.

Improper Fit Damage

Bearing cone (inner race) bore damage

Bearing cone (inner race) bore damage:
Fractured cone due to out-of-round or oversized shaft.

Bearing cup (outer race) spinning

Bearing cup (outer race) spinning:
Loose cup fit in a rotating wheel hub.

Foreign Material Damage

Abrasive wear

Abrasive wear:
Fine abrasive particle contamination.

Bruising

Bruising:
Debris from other fatigued parts, inadequate sealing or poor maintenance.

Grooving

Grooving:
Large particle contamination embedding into soft cage material.

Peeling

Micro-spalling

Micro-spalling:
Due to thin lubricant film from high loads and low RPM or elevated temperatures.

False Brinelling

False Brinelling

Wear caused by vibration or relative axial movement between rollers and races.

Electric Current Damage

Electric arc pitting

Electric arc pitting:
Burns created by improper electric grounding while bearing is stationary.

Fluting

Fluting:
Series of axial burns caused by electric current passing through the bearing while rotating.

Corrosion/ Etching Damage

Staining

Staining:
Surface stain with no significant corrosion from moisture.

Etching

Etching:
Rusting with pitting and corrosion from moisture.

Line spalling

Line spalling:
Roller spaced spalling from bearings operating after etching damage.

True Brinelling

True Brinelling

Bearing damage from shock or impact.

Misalignment Damage

Misalignment Damage

Irregular roller path from deflection, inaccurate machining or wear of bearing seats.

High Spots In Cup Seats

High Spots In Cup Seats

Localized spalling on the bearing cup (outer race) from stress riser created by split
housing pinch point.

WARNING Failure to observe the following warnings could create a risk of death or serious injury.

Do not attempt to disassemble and reassemble unitized wheel end hubs and bearing assemblies. Improper reassembly could lead to failure.

Proper maintenance and handling practices are critical. Always follow installation instructions and maintain proper lubrication.

Tensile stresses can be very high in tightly fitted bearing components. Attempting to remove such components by cutting the cone (inner race) may result in a sudden shattering of the component causing fragments of metal to be forcefully expelled. Always use properly guarded presses or bearing pullers to remove bearings from shafts, and always use suitable personal protective equipment, including safety glasses.

 

CAUTION Failure to follow these cautions may result in property damage.
The products cataloged are application specific. Any use in applications other than those intended could lead to equipment failure or to reduced equipment life.

Use of improper bearing fits may cause damage to equipment.

Do not use damaged bearings. The use of a damaged bearing can result in equipment damage.

 

TechTips is not intended to substitute for the specific recommendations of your equipment suppliers. Every reasonable effort has been made to ensure the accuracy of the information contained in this writing, but no liability is accepted for errors, omissions or for any other reason.