Following a recent “high-hazard event” involving a vehicle fire in a coal mine, the NSW Resources Regulator is emphasising the need for regular inspections of universal joints on underground vehicles.
The incident occurred when an operator was driving a personnel carrier underground and heard an unusual noise. After stopping the vehicle, the operator observed a 20–30 mm flame coming from a universal joint on the front drive shaft, and proceeded to extinguish the flame using a fire extinguisher and then doused the area with water.
The vehicle was operating in two-wheel drive at the time, meaning there was no load transfer through the universal joint. According to the regulator, the transmission and front differential were found to be in good condition.
The universal joint was a ‘sealed for life’ type. Investigations showed the needle bearings had fallen out of the joint, and the universal joint was described as being “red hot” at the time of the fire. The component has been sent for metallurgical analysis to determine the cause of the failure.
A fire on a vehicle in an underground coal mine, the regulator said, is considered a high-hazard event with the potential to impact workers underground. Universal joints normally transfer large torque loads, and one known failure mode is the generation of frictional heat that can ignite lubricants and initiate a fire.
In light of this, the regulator’s recommendations to the industry stress the importance of regular checks of universal joints on underground vehicles to reduce the risk of fires. Periodic inspections should be conducted in line with manufacturer recommendations and include confirming lubrication and seals are intact, checking for mechanical looseness, identifying vibration or imbalance, and verifying components against established discard or end-of-life replacement criteria.
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