There are two types of 40 tonne trucks for sale at Truckpages – 4×2 tractor units (used with 3 axle trailers) and 4×2 rigids capable of towing a 3-axle drawbar trailer.
We understand that he tractor unit itself does not have a gross vehicle weight (GVW) of 40 tonnes. In reality, as they only have two axles, the GVW is 18 tonnes – that is why you see a 4×2 MAN tractor unit with the model of TGX 18.440 – the ’18’ part signifying 18 tonnes and the 440 representing the engine power in BHP. The same is the case for Mercedes with their 1843 (18 tonnes and 430BHP).
So why are they in the 40 tonnes category?
When pulling a tri-axle semi-trailer, a 4×2 tractor unit has a Gross Train Weight (GTW) – sometimes called Gross Combined Weight (GCW) of 40 tonnes.
The most common of the two types in the UK are 4×2 tractor units. These are typically used only on operations that carry lighter materials – ones that “cube out before they gross out”. That means the trailers are full, but they still don’t weigh over 40 tonnes fully loaded.
If this is the case, there is no point carrying around the extra axle on the tractor unit – although in many cases it is easier to remarket a 6×2 tractor unit than a 4×2 at 40 tonnes GTW.