Conveyor Drive Pulley Bearing Overheating and Collapse Under High Bulk Material Load
Technical investigation of catastrophic drive pulley bearing failure caused by thermal overload and lubrication degradation in a high-capacity mining conveyor system.
Operational Symptoms and Failure Detection
Operators reported abnormal vibration and elevated bearing housing temperatures during continuous high-tonnage ore transfer cycles. Infrared thermal inspection recorded localized temperatures exceeding 118°C near the drive-side pulley bearing housing. Progressive belt mistracking and intermittent metallic noise were detected several hours before shutdown.
Drive Pulley Function and Bearing Load Characteristics
The conveyor drive pulley transmits torque from the electric drive motor to the conveyor belt through frictional traction. The spherical roller bearing assembly supports combined radial and axial loads generated by belt tension, material surge loading, and pulley misalignment under continuous-duty operation.
Failure Mechanism and Inspection Findings
Disassembly revealed severe lubricant carbonization, rolling element surface spalling, and collapse of the bearing cage assembly. The grease cavity contained metallic debris and fine abrasive contamination particles. Raceway inspection identified thermal discoloration and localized micro-pitting caused by breakdown of the elastohydrodynamic lubrication film.
Root Cause Analysis
The primary failure mechanism originated from insufficient grease replenishment intervals combined with prolonged operation above the conveyor system's nominal material throughput. Elevated thermal loading reduced lubricant viscosity stability, while contamination ingress through damaged labyrinth seals accelerated abrasive wear within the rolling contact surfaces.
Corrective Maintenance and Reliability Improvements
The failed bearing assembly was replaced with a new SKF spherical roller bearing set, and the pulley shaft journals were inspected for dimensional deviation and thermal scoring. Conveyor alignment was recalibrated, damaged labyrinth seals were replaced, and an automated centralized lubrication system with temperature-triggered monitoring was installed. Additional vibration monitoring points were integrated into the predictive maintenance program.
Prevention
Implementation of automatic centralized lubrication, thermal condition monitoring, vibration trend analysis, and scheduled pulley alignment inspections in accordance with OEM conveyor maintenance procedures.