Carryfast:
I’m more familiar with 6x2 rigid and a-frame drawbar trailer type outfit than with artics and that’s the point of view I’m writing from. I’ve also always thought the same way as you about rigid+trailer behaving better than artic in bad conditions. Still that doesn’t change the principles behind the way how you can get more traction from a 6x2 vehicle and on some cases that traction is more than you’d get from a 6x4 vehicle. I also agree with you on that under right conditions difference between 6x2 and 6x4 is like between day and night into a favour of 6x4 and that generally 6x4 is not that prone to differences in available grip than 6x2 is.
I clearly can’t understand the way yanks are thinking as I’ve not grown up to their way of thinking, but I think I can still wonder why they think 6x2 will never be practical choice for a drivetrain?
What I can understand are the practical reasons behind the popularity of the 6x2 vehicles in Finland and the reasons why one can get enough traction from them in Finland. I also think that Swedish operators think same way as Swedish and Finnish lorries have quite the same axle and drivetrain configurations. From what I’ve seen Finnish companies driving to Norway also think they can get enough traction with 6x2 vehicles (drawbar or artic) and based on pictures I’ve seen most Norwegian operators seem to think just the same way.
I also understand there are different practical reasons for chassis configuration on vehicles regularly encountering bad conditions, like loggers, but if thinking only vehicles operating mostly on firm surfaces (practically meaning all vehicles with curtains, boxes or tanks) 6x2 has many benefits over 6x4 in Finland. I think most important of those benefits are:
- improved payload
- reduced fuel consumption
- reduced tyre costs
- better manoeuvrability because of reduced turning circle when tag is up
- easier to reverse when tag is up (at least rigid).
There are also some cons and I think most notorious ones are:
- Difficulties to get moving on snow or ice after being stationary long enough (like from a loading bay).
- Lack of traction at slow speeds while loaded.
When thinking those from owners point of view, pros for 6x2 easily overcome the cons (in Finland). When thinking from drivers point of view most benefits important to owners are not that important, but as we don’t know about anything better, like you’d probably say, most of the drivers just have learned various tricks to overcome the difficulties their drivetrain causes them at winter. Also Finland is somewhat flat, compared for example to Norway or to Rocky Mountains -area, so we don’t end up running that much at slow speeds where traction problems would arise to a constant concern. In Norway they have more hills but they still seem to prefer 6x2 configuration. Generally they also have bigger engines and less weight to compensate this (600+ horses for 50 tonnes compared to 420-500 horses for 60 tonnes in Finland). Norwegian lorries also this distinctive looks which immediately tells that they are regularly using those chains hanging from their lorries (like removed mudguars 
).
Then, just to clarify things, some pictures and videos with some commentaries.
Not ordinary winter weather in Finland, but still it’s common to have snowfalls of about this intensity.There were no reasons to drop speed below 80 km/h limit (although at times visibility could’ve been better). Traction problems were non-existent at higher speeds as my engine didn’t have enough power to get drive axle spinning anymore at speed above 70 km/h despite my rigid being quite front heavy and approx. 15-20 tonne trailer behind me. But like said before, getting a wheel to spin at those speeds generally require so much power from engine that no lorry has it.
This is what could be considered “ordinary winter weather” by road administration. Clear, crisp weather and enough minus degrees so the friction is somewhat constant. It doesn’t matter that road has thin ice coverage as it’s part of the “ordinary winter weather”.
It’s very typical for tippers to do snow ploughing at winter like these two 6x2 tippers (note the “plough under the belly” and attachments for front plough). I guess they have huge difficulties while ploughing or gritting small Finnish roads at winter or then they don’t need double drive as motorways are non-existent at that region.
Then, as yanks clearly like their double drives what if they could lift rearmost axle up when running empty and still have genuine double drive without any Robson drives I mentioned previously?
8x4 tipper with rearmost drive axle lifted up and it’s drive disengaged. Note the similar hubs in rear wheels indicating it has double drive. You still get diff- and crosslocks for this “double drive with lift axle” making it by every mean as powerful as ordinary 6x4 but giving you more traction when empty and better turning circle.
If you aren’t believing that vehicle has double drive, then have a look to these two videos:
Interesting part begins from 0:16. Also note similar snow plough equipments as mentioned before.
Interesting part is from 2:19 to 2:30.
From first video you can see what kind of look a hub on a free rolling axle on this make (Sisu) has and hub on the picture of the 8x4 lorry clearly isn’t such. From second video you clearly can see that it really is double drive as rear axles turn at same pace despite another being on air. First video also show the Robson drive in action.
What about this kind of devices in US on lorries which don’t regularly encounter long, steep and snowy hills?
There’s no way that road wouldn’t be ploughed at least once during that day. If you’re wondering how I’m that certain road has been ploughed check 
Opening unploughed roads, like two closed lanes on a three lane motorway, requires far more traction than ploughing roads which are kept open constantly. Also you in the UK are more likely to get most of the snow as a “wet snow” or sleet opposed to “frozen snow” and the latter hinders traffic much less. Those reasons might partially explain why 6x2 snowploughs seem to manage well here, but they still do well even on ploughing unploughed small roads.
) of ours.
