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Mineral Mines & Quarries Inspectorate | Bulletin | No.209 V 1 | 25 January 2023

High speed bearing fires on underground loaders

What happened?

In the last 12 months, there have been five fires involving the high-speed (drive shaft) bearings on underground loaders in Queensland metalliferous mines. These have occurred across different mines, with some mines having multiple fires (refer to Figures 1-5).

Although no one was injured in the incidents, the fires had the potential to cause significant adverse effect to the safety or health of workers. One of the fires was unable to be extinguished, causing a mine evacuation and shutdown for several days and total loss of the machine.

How did it happen?

A common cause of the incidents was found to be the overheating of the high-speed (drive shaft) bearing of the loader.

Key issues

Common contributing factors in the incidents were:

  • failure of the bearing lubrication, from blockages in grease lines or using grease with the incorrect specification (grease with Molybdenum Disulphide or other solid additives).
  • preventative maintenance programs did not identify premature wear or defects in the bearing during inspections.
  • preventative maintenance programs did not specify an appropriate interval change-out frequency for the bearing.
  • AFFF fire suppression systems had insufficient coverage, as the bearing was covered by a sheet-metal guard.

The Original Equipment Manufacturer (OEM) released a Safety Bulletin in 2018 detailing the hazards of using the incorrect specification grease in high-speed bearings, and actions to be taken immediately.


Mines should:

  • ensure grease used to lubricate underground loader high-speed bearings is the correct grease type as specified by the OEM.
  • ensure preventative maintenance programs for underground loaders include inspections to identify lubrication failures, premature wear and early signs of bearing failure.
  • ensure preventative maintenance programs for underground loaders set an appropriate change-out frequency for high-speed bearings in consultation with the OEM and based on site conditions.
  • ensure an effective system exists for the identification, communication and inclusion of OEM safety and service bulletins in the site's preventative maintenance program.
  • ensure AFFF fire suppression systems for mobile equipment have been designed and engineered in accordance with relevant standards, such as AS 5062:2022 - Fire prevention and protection for mobile and transportable equipment.

References and further information

Authorised by Hermann Fasching - Chief Inspector – Mineral Mines & Quarries

Contact: Rob Henson, Inspector of Mines , +61 7 4745 4114

Issued by Resources Safety & Health Queensland

Safety: This information is issued to promote safety through experience. It is not to be taken as a statement of law and must not be construed to waive or modify any legal obligation.
Placement: Place this announcement on noticeboards and ensure all relevant people in your organisation receive a copy, understand the content, findings and recommendations as applicable to their operation. SSEs should validate that recommendations have been implemented.