The Kenworth prime mover was on a trip between the Melbourne suburb of Ivanhoe and St Marys in western Sydney in March this year when the driver was pulled over by RMS officials at Marulan just before midnight. The driver told inspectors he knew one of the shock absorbers on the rear trailer was broken, prompting the authority to carry out a full inspection of the vehicle and its two trailers, which were carrying a load of steel at the time.

Officials said they found multiple defects throughout the set-up, including major issues with the brakes that caused the truck to be taken off the road immediately.

In a report tendered to Port Kembla Local Court this week, the RMS said investigators discovered a more than 30 per cent difference between the braking capacity of the wheels on multiple axles on both trailers.

The poor results of the examination led officials to issue the truck with a "major grounded defect", meaning it was immediately deemed unroadworthy and had to be towed from the scene.

When asked about whether he'd told anyone about the broken shock absorber, the driver replied, "I told the boss ... but it still hasn't been fixed".

It was also discovered the seat belts in the driver's cabin were not secured.

McCabe Transport director Tony McCabe pleaded guilty to a charge of using an unsafe heavy vehicle on a road in court this week and was fined $1500.

The penalty comes nine months after McCabe Transport was fined $241,000 and ordered to pay $81,000 in legal costs after pleading guilty to 159 charges relating to employees working excessive hours and falsifying log books.

In that case, the court heard McCabe set impossible schedules for his long haul drivers to meet without breaking driver safety laws - a matter the presiding magistrate described as appalling.