As well, the Newcastle Herald has obtained photos of two earlier accidents involving the same or similar types of trucks at Mount Arthur, one from 2009, the other from 2007.

The truck in Wednesday's mishap has been identified as a Liebherr T 282, which the manufacturer says has a gross weight of 600 tonnes including a maximum payload of more than 360 tonnes.

The truck uses an electric direct drive system made by Siemens, with the power generated through a massive 2.7 kilowatt (3650 horsepower) diesel engine.

The electric drive also features an "anti-rollback" system, which is designed to stop the truck rolling down a hill once propulsion is started.

Sources familiar with Wednesday's accident said the truck was taking rock away from "a new dig area" being cut by the excavator in the original photo.

"The gradient up the hill is about 10 per cent and it looks like the driver has lost power pulling away, and as they've gone backwards the anti-rollback has kicked in," the Herald was told.

"Somehow, either the load was too heavy at the rear or it has shifted back, taking the centre of gravity with it, and up goes the front."

A MOUNT Arthur coalmine dump truck driver escaped serious injury on Wednesday morning when his laden truck became too rear-heavy, tipping his front wheels and cabin into the air and leaving the truck sitting on its tailgate.

There was no clear explanation yesterday as to how the truck ended up as it did, but it appears that the load in the truck shifted backwards as it went up an incline, unbalancing it towards the rear.

Both Mount Arthur and the Resources Regulator said an investigation had begun.

Mount Arthur management said the driver was treated at the scene.

"He only sustained minor muscle injuries, and did not need to be conveyed off-site for further assessment or treatment," the company said.

Later in the day, the regulator said in contrast that "no one was injured".

The incident was almost two years to the day after a contract worker was seriously burnt in a refuelling incident that will cost the BHP subsidiary almost $1.1 million in an "enforceable undertaking" struck with the Resources Regulator.

In setting its penalty this week, the regulator said the company had "demonstrated appropriate contrition" over the August 10, 2017, incident.

But unhappy former Mount Arthur workers say the incident itself, and the way that management handled it, represents the "tip of an iceberg" when it comes to safety and compliance problems at the BHP subsidiary.

Simon Turner, a former contract worker who was sacked after being injured at the mine in December 2015, said yesterday that he and others had told the authorities about various safety problems and reporting shortcomings at Mount Arthur.

Mr Turner - who is the lead claimant in a class action over the treatment of casual workers at Mount Arthur and other mines - said workers were still being pressured not to take time off after workplace accidents.

This helped keep lost-time injury rates down, and meant the company did not have to report the incident to the Resources Regulator.

Mr Turner suffered work-ending spinal damage in his own dump truck accident in December 2015 when his truck was hit by by the bucket of an excavator, throwing him around the cabin.

A Resources Regulator review of Mr Turner's case says Mount Arthur did not report the incident, treating it as a "first aid" case despite him being taken to hospital.

Although the regulator says it issued an improvement notice to Mount Arthur in 2016 to "ensure that all notifiable incidents are reported to the regulator", Mr Turner and other mine workers say under-reporting is still an issue across the Hunter industry.

Mount Arthur declined to respond to any of Mr Turner's statements.

FURTHER READING: Glimpses only, of coal's safety record

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