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Cage Failure in a Mobile Equipment Drive

Effect of poor lubrication on a tapered roller bearing

In drives for mobile equipment, high speed tapered roller bearings from the input shaft failed due to cage fracture. The root cause was identified as an insufficient quantity of oil which led to overheating, subsequent wear, increased forces between rollers and the cage and, finally, cage collapse.

Cage Failures in Railway Gearboxes

Käfigbrüche in Bahngetrieben
Fractured cage

Cylindrical roller bearing failures due to cage fracture were observed in numerous wheelset gearboxes. Our investigations detected vibrations during operation that exceeded the cage strength as defined by its geometry and material.

Wear in a Bearing in a Large Industrial Gearbox

Endoscopy of a spherical roller bearing in a large industrial gearbox

An endoscopic inspection of a large industrial gearbox was arranged due to conspicuous noise during operation. The inspection showed wear on the rollers. The cause was identified as poor lubrication during a subsequent visual inspection.
Following the inspection, the replacement of the affected spherical roller bearing and repair of the gearbox can be planned while taking operational needs into account and minimizing the costs due to the loss of production.

Bearing Damage in a Gearbox for Wind Energy Converters

Shoulder fracture of a bearing’s inner ring

A planetary gear bearing failed due to shoulder fracture of the inner ring in the gearbox of a wind energy converter. In this case, metallographic investigations detected a fault during heat treatment that caused severe local brittleness.

Electrical Discharge in Industrial Plants

Damage to a bearing ring due to electricity

Unexpected bearing fatigue was observed in several industrial plants. Our investigations determined the source to be an electrical discharge that could be traced back to defective insulation.

Poor Lubrication in an Industrial Gearbox

Typical wear pattern resulting from poor lubrication

Poor lubrication lead to a typical wear pattern on the gears and bearings and, finally, to bearing failure in an industrial gearbox.

Bearing Failures in Electric Motors

Rolling contact fatigue

Pitting was found in the rotor ball bearings of several electric drives emitting conspicuous amounts of noise. The root cause was determined to be excessive tension in the housing caused by improper mounting of the bearings. This lead to increased loads in the bearings, which caused higher temperatures and significantly reduced their lifetime.

Tooth Foot Fracture in an Industrial Gearbox

Tooth root fracture

A tooth foot fracture in a large industrial gearbox was detected in the final stage. The root cause was an improper contact pattern, which could itself be traced back to deflections in the housing. In addition to visual inspection, endoscopy and fracture face analysis, finite element simulation was used to determine the root cause.

Tooth Flank Fatigue in a Wind Energy Converter

Flank Fatigue

Pitting on the gear flanks was detected in the main drive of a wind energy converter gearbox. In addition to an improper contact pattern, an excessively large grain size in the material was detected which reduced the flank strength.

Wear in Gearboxes for Wind Energy Converters

Fresser auf Ritzel
Fretting on teeth

Skipping required maintenance led to a significant deterioration of oil quality in the gearboxes of several wind energy converters and thus to both worn gears and failed bearings.

Fracture of a Torque Support Rod

Gebrochene Drehmomentstütze
Fractured torque support rod

This fracture of a torque support rod from a wheelset gearbox was caused by extraordinary loads throughout the entire system.

Fracture of Bolts

Fatigue failure of a bolt

Several bolts broke beneath their heads due to fatigue. Based on the fracture faces, cyclic deformation of the connected parts was identified as the root cause.

Fatigue Fracture of a Welded Shaft

Fatigue failure of a shaft

The rotor shaft of an electric multi-megawatt drive failed due to a fatigue fracture. Torsional vibrations based on the plant configuration were identified as the root cause.