Published in September 2006 Australian Longwall Magazine

Marathon Tyres national product line manager for the Reusable Rubber Liner (RL) Mike Marshall said over the past 10 years, the manufacturers of underground coal mining equipment had been designing loaders, ram cars and shuttle cars to handle heavier loads, without increasing the tyre size being fitted.

Tyre pressure and load are directly related. Marshall said he had witnessed a domino effect as bigger loads warrant higher tyre pressure recommendations to accommodate for the extra weight.

“The heavier loads require higher tyre pressures to meet the load and consequently the risk of damage and exploding tyres from rock cuts become a safety concern,” he said.

With mine safety under the microscope, Marshall said the emergence of the Marathon RL into Australia’s underground coal mines has eliminated some of the risks associated with pneumatic and polyurethane tyres.

“The RL has come at a time where the world tyre industry has a chronic shortage on earthmoving tyres and with an RL fitted, the tyre is now able to be run into the belts with no issues of safety,” he said.

“This has also increased mileage and assisted the industry in reducing costs while tyres are in short supply, as tyres normally damaged beyond repair and heading for the scrap heap can still be used if an RL is fitted inside the tyre.”

Marshall said higher tyre pressures have also led to questions being asked about the suitability of the wheel rim to handle these pressures.

“If the wheel rim is not suitable for the higher tyre pressures, it will become the inhibiting factor to the growth of the pneumatic tyre in this market.”

“If the wheel is capable of handling these higher loads, then the pneumatic tyre becomes the new risk.”

Marshall said it had to be questioned how safe miners were today with shuttle cars running on 14.00 R 24 tyres now needing 125psi to keep up with loads, as well as rib bolts being a common source of tyre punctures in coal mines.

“When a pneumatic tyre has the sidewall ripped out by a rib bolt in a tunnel – what effect will this explosion have on the driver and the rest of the workforce in the vicinity? What would happen if we had a cracked wheel rim that led to an explosion where metal fragments ended up as missiles?” he said.

Marshall said the introduction of the RL into Australia’s underground coal mines had removed many of the risks and made tyres safer.

“The RL has also come at a time where the world tyre industry has a chronic shortage on earthmoving tyres.

“With an RL fitted, the tyre is now able to be run into the belts with no issues of safety, which also increased mileage and assisted the industry in reducing costs while tyres are in short supply.

“Tyres normally damaged beyond repair and heading for the scrap heap have now been able to run if an RL is fitted inside the tyre.”

Once fitted with an RL insert, a tyre can never be punctured, Marshall said, which in turn allows the client to run the tyre smooth.