The Subject of Rollovers

For livestock transporters, the subject of rollovers is particularly delicate. Much of the livestock transporting industry runs with trucks at 4.6 metres in overall height. This obviously creates a high centre of gravity in a load which can also move about on a vehicle. A recipe for disaster.

Safety issues are constantly being looked at in all transport, but different aspects of the issues are of interest to different sectors. The science behind rollovers is little understood in the trucking industry and Mike Robertson, Managing Director and Engineering Manager at Engistics, took on the subject for the livestock community to help bring the issues into a clearer light.

“In an accident I investigated a couple of years ago, the company concerned rang me and explained their disbelief,” said Mike. “They couldn’t understand what had happened. The same driver had driven the same truck, carrying the same load, on the same corner 57 times before. On the 58th trip, it rolled and totalled the truck.

“How do trucks roll over? Prime mover centre of gravity is low, but on the load the centre of gravity is high. They roll over from the back, surprise, surprise. Typically, the back twists and then you get a flick on the prime mover. Stock crates are a little different, because they have torsional resistance. This makes them stable, but when they go, they go quickly.”

Mike emphasised the way trucks roll over means the driver does not get any feedback as the trailers starts to go over and often brakes after the trailer has fallen over.

“You don’t have to have to have many more km/h to have a disproportionate effect on vehicle stability,” said Mike. “So what I’d like to do is invent something which, when the truck gets near to the point of rollover, intervenes before the driver can. However, someone has invented the electronic rollover and stability programs already.”

Electronic braking systems (EBS) and stability programs have met with quite a lot of resistance from the rural carriers, as have anti-lock braking systems (ABS), in the past.

Amendments to Australian Design Rules 35 and 38 will see the introduction of EBS as mandatory on many trucks. In a discussion about the use of EBS and stability control, Mark Johnston from Haulmark Trailer stated he was not against this new technology, but did have reservations.

“What I am concerned about is when the braking ADR comes in, as a manufacturer we will fit EBS and stability control to everything we build,” said Mark. “This is where it concerns me, some cases where this may not be appropriate, based on where this vehicle is operating. I worry about operators in remote and off-road type applications.

“We’ve fitted a few EBS systems over the years, and, in general terms, it works OK. We found there are some service requirements if you are in remote areas. We have livestock clients who are on dirt for 95 per cent of their life and they could be away from their workshop for five or six weeks at a time.”

One fleet expanding its use of EBS is Stockmaster, from Tamworth. Owner Robert Cavanagh says he has a high level of acceptance of the technology from his drivers.

“The thing that sold me on it was when drivers told me it made them pick a better line into a corner,” said Robert. “The second point, and probably more important, is that on long shifts when they go through a corner and feel the brakes come on, it’s a clear warning sign to them, they are not on the job.”