Why so many axles?

[saur44l]

This is a question for our fellow forum members from the USA,here in Europe we don't have anything even remotely similar like this,what is the purpose of so many axles on the construction trucks.

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[marcel-dutch]

It is very simple: the maximum weight per axle. In Europe is the maximum weight per axle higher than in the USA. More axles is less weight per axle.
In Europe has a concrete truck 4 axles and on the photo 7 axles.

[TruckSimChris]

This truck is actually from a local company in my state called Stoneway. In my state, Washington, our weight limits are a little bit higher than the national standard, so we require more axles to haul more weight (look at the red truck in my signature for an example).

The weight formula in the US is much more complicated than the EU, and every state has different weight laws, so explaining it all would take too long. However, this 6-axle concrete mixer with a wheelbase of approximately 35 feet would be allowed to carry around 70,000 lbs (31 tonnes).

Notice at the very back there is also a retractable seventh axle that can be raised or lowered. When the seventh axle is lowered, the wheelbase is extended approximately 8-10 feet more, which would allow it to carry up to 80,000 lbs (36 tonnes).

Here's a better side photo:
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By the way, we refer to this type of axle configuration as a "Super 18" because it has 18 tyres.



For comparison, a traditional 3-axle concrete mixer with a similar wheelbase would only be allowed to carry 50,000 lbs (22 tonnes), so quite a significant weight difference.

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[kitt94]

This is a lil' bit crazy.

[Mohegan13]

We don't have 12x in Europe but we get plenty of 8x versions and there's the rare 10x to be found.

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[Wolfi]

Well, we also get this thingy:
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[Trident R.S.]

5 axle trucks are permitted even in swiss (gross weight 40ton).
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[saur44l]

Thanks for your answers guys,I thought that it has to do something with the weight but I wasn't sure,it has to be a real nightmare when it comes to suspension maintenance with so many wheels plus four liftable axles.I take it that this kind of vehicles are common site in the US........SCS come on people,it is about time to include them in the traffic AI.

[TruckSimChris]

@kitt94: Perhaps it's a little bit crazy.

But you have to understand we require many axles because we prioritize protecting our roads and bridges. That's why we call our weight law the "Bridge Formula".


@saur44l: No, 6 or 7 axles for a concrete mixer is only legal in a few states (including mine, as I said). These are actually very rare in most of the US. The most common throughout the US is the 3-axle one I showed. Like I said, every state has different weight laws, therefore different allowable axle configurations.

Depending on what state you're in, you might also see a 6-axle version:
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...a 5-axle version:
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...or a 4-axle version:
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Adding to this, Michigan has a much different weight formula compared to the rest of the country, so they allow much more weight. This front discharge mixer made by Oshkosh is most common in Michigan, and they are allowed to carry a gross weight of 55 tonnes:
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I hope this all makes sense. It's very complicated to explain it all in detail, as you can see.

[saur44l]

I hope this all makes sense. It's very complicated to explain it all in detail, as you can see.

Hmm,now I feel sorry for the truck manufactures there........Nevertheless they all look beautiful and quite unusual,so it will be nice to have them in the game,maybe when they add OR and WA states ........once again thanks for the information mate.