When mud or sand have swallowed the road, the only way to stay out of trouble is to keep moving. This is where the driven front axle in the Volvo FMX is hard to beat. And even harder to beat now that it’s equipped with the new Automatic Traction Control (ATC), a clever feature that automatically engages the front axle when it’s needed.
It’s hard to believe the construction segment manager in his clean white shirt has just come home from a mud bath in Brazil. Until he starts talking about the benefits of the new automatic all-wheel drive
Commonly known as the Oh Shit!-button
”Our driven front axle has always been designed to be selectable and easy to engage when you need it. But we wanted to develop it further to take away some stress from the driver. With Automatic Traction Control, they can always be sure to have the traction they need, but only when they actually need it,” says Jonas Odermalm.
Steeper hills and deeper ditches
The front drive axle has been relocated 100 millimetres closer to the front. This gives the truck a far better approach angle, but also means it can be combined with the full range of chassis components and engines. From crown and pinion to bearings, the axle is completely new. Its design makes it stronger, more streamlined and provides better ground clearance.
“Previously the lowest part was the parallel rod, but this has been integrated behind the axle beam. So now the lowest point of the vehicle is the sturdy axle casing. When fully laden the truck has significantly improved ground clearance. Together with the new approach angle, this makes it very versatile on uneven terrain,” explains Jonas Odermalm.
Lower fuel consumption
While permanent all-wheel-drive is the common solution for construction trucks, Volvo has taken a different approach. Jonas Odermalm recalls from research carried out in the desert: “It’s really only needed between two and five percent of the time. This means that 95 percent of the time a driven front axle is a waste of fuel – unless it’s an FMX equipped with Automatic Traction Control.”
When conditions allow, the system automatically disengages the front axle. This means direct transfer between the engine and rear drive axle, so the other wheels are free rolling – and consuming less fuel. The truck also becomes easier to manoeuvre when the grip of the front tyres can be dedicated to steering. On top of this, there is less wear and tear on the front axle.
When things get extreme
In the six-wheel-drive trucks the first thing you need is an inter-axle differential lock – diagonally locking two of the rear drive wheels across the bogie. According to Jonas Odermalm, this is enough for many situations. “If things start getting really slippery you engage the driven front axle. This gets you out of most situations – now we are entering extreme mobility.”
“Then we have what is commonly known as the Oh Shit! button. Pressing this locks the front differential making it very hard to steer the vehicle – but allows you to get back onto dry land.”
On and off
When asked about the attraction of this type of mobility, Jonas Odermalm is quick to respond. ”ATC provides all the benefits of a selectable driven front axle, while being just as convenient as a permanent system. I think it’s appreciated by drivers of all sorts of vehicles: 4×4 service vehicles for road maintenance, 6×6 tippers working on desert oil pipes, 8×6 dump trucks in quarries and 10×6 cranes on sandy construction sites."
He adds, “Of course, it wouldn’t be so attractive without our reputation for durability and reliability.”
Learn more about Automatic Traction Control