Suspension in the new Volvo FM has been completely revised to match the handling performance of the new Volvo FH. In particular, course stability and steering control are noticeably improved. The Volvo FM might even feel like it hugs the road more – as the driving position is lower.
In geometry the smallest changes can sometimes make the biggest differences. Vehicle dynamics expert Niklas Fröjd begins with an example of this – the positioning of a stabiliser.
“When a fully loaded truck starts cornering there is a lot of roll torque coming into the tractor frame from the trailer. This force can feed through to the axles and cause wheel misalignment – an unpleasant sensation for the driver who will need to compensate for it. But by placing the stabiliser close to the fifth wheel position, that force now gets fed into the ground. This makes a big improvement to the cornering stability of the truck.”
Everything is either replaced, upgraded or enhanced
One thing leads to another
The new stabiliser position is also helpful in evading the forces that normally enter the chassis from an uneven road surface. This, of course, makes the ride more comfortable and improves course stability. A further benefit occurs in cornering:
“Let’s say you are driving round a roundabout – the cornering forces cause the cab to roll. But the new stabiliser installation in the rear suspension reduces this. The trailer now transmits much less force to the cab.”
Inclined to behave better
Steering control too, has been sharpened by geometry. “We have introduced a slight inclination in the suspension system,” says Niklas Fröjd tipping his outstretched hand a little. “Of course, none of this is visible, but previously it was parallel to the ground. The new angle creates a slight counter steer when you’re turning and cornering.”
Apart from preventing any tendencies to oversteer, this is one of the things that allows you to choose your line through the road ahead and then feel how the truck follows it.
Every little thing
In combination with its improved geometry, the entire suspension has been revised and fine-tuned. So everything is either replaced, upgraded or enhanced to achieve the desired result – spring stiffness and damping systems, for example. Even the engine suspension is improved to cause less vibration. Less vibration means less fatigue for the driver. And a driver who feels good is safer than one who is jarred and exhausted.
Stefan Axelsson has been responsible for verifying the performance of the new suspension. He likes the fact that he feels he can trust the truck in tricky situations where there’s little margin for error. “When you meet an oncoming vehicle on a country road, for example, your mind goes through the margins in a fraction of a second. It’s at this point you discover how much steering control you have in the truck,” he says.
Stefan Axelsson thinks long and hard before answering. “Not really, more of an insight I suppose. It’s surprising how exactly you can drive it on a winding road – now that it has car-like handling qualities. With other trucks you wouldn’t dare push it so hard.”
The real thing
Niklas Fröjd believes this has a lot to do with the tightness of the new set up. “There’s nothing masking your interpretation of the road, the geometry makes it feel more connected. And because it forms a dynamically stable truck and trailer system, it’s also more comfortable.” He admits that he’s proud, but what finally comes across is a sense of personal satisfaction. “You get what you want out of it – it feels like real driving.”