6×2 trucks all have three axles, only one of which is a drive axle. This sounds straightforward but becomes more complicated when you consider the types of trucks involved.
On these pages we will consider 6×2 rigid trucks – including those pulling a drawbar trailer and tractor units – the most popular type of truck sold in the UK.
These are trucks that, by definition, are not articulated (compared to tractor unit and semi-trailers which are articulated.)
The drive axles are distinguished by usually having two sets of wheels and tyres on each end of the axles. This means that they are legally allowed to carry ten tonnes, as the load is spread over a greater surface and therefore does less damage to the roads.
The remaining two axles typically have just one wheel and tyre on each end of the axle. This means the most that they can carry is eight tonnes each.
Some simple maths tells us that the most these trucks can carry is 2 x 8 plus 10 tonnes – or 26 tonnes Gross Vehicle Weight.
On a 6×2 rigid the front axle will always be a ‘steer’ axle, (otherwise going around corners would prove very difficult). The other non-drive axle could be a steer axle – these are usually seen on vehicles with an urban duty cycle, such as refuse trucks.
A rear steer axle will generally make a truck more manoeuvrable.
Lift axles are employed to save on tyre wear when the truck is not running at full capacity. Using hydraulics, the axle is lifted clear of the floor. Where the axle is located in front of the drive axle, this is known as a mid-lift axle – when it is at the rear then it is called a rear-steer or a tag-axle.
These trucks are simply a normal 6×2 rigid with a special drawbar coupling at the rear to allow them to pull a drawbar trailer. These are not classes as tractor units as they are not articulated with a fifth wheel coupling. The trailers can stand on their own when decoupled as they typically have a minimum of two axles spaced centrally.
In addition to the coupling, rigid trucks that are set up to pull drawbar trailers will have more powerful engines, as the combination weight is approaching that of a tractor unit and semi-trailer in the UK at 40 tonnes gross train weight (GTW).
These are the most common type of truck on the UK’s roads. Unlike through the rest of Europe, tractor units with this extra axle (most continental tractor units are just 4×2) means that they can legally carry an extra four tonnes GVW in the UK (44 vs 40 tonnes). In terms of operating efficiency these trucks are typically preferred for all except high volume, low weight operations (think carrying polystyrene).
6×2 tractor units can also have a choice of lift axles – mid or rear lift axles.
Read more about tractor units here…>
