Considering yanks only run at about 36tonne and the Canadians are 44 similar to us, why do both countries seem to spec every single truck with double drive?
Even for trucks that would never go off a trunk road let alone off road. Surely this costs a fortune in initial cost, fuel and lost payload?
Notice the trailers only seem to be 2axle too, this compounds my confusion further…
The 6x4 units have probably got more to do with yee haa yankee image than anything else, the amount of bling being a case in point. North American, Australian and some European trailer specifications on the other hand just show up British equipment for what it is - come to think of it actually the entire British haulage industry for what it is, - a complete joke.
cav551:
The 6x4 units have probably got more to do with yee haa yankee image than anything else,
More like the only logical solution to the combination of strict axle weight limits and harsh weather conditions varying from tyre shredding high road surface temperatures to deep soft snow or ice.Bearing in mind that at anything more than half the drive axle weight,of a typical 4 x 2 or 6 x 2 Euro spec,x 2,equals an unarguable net increase in traction,while obviously applying almost the half the axle weight to the road.Thereby keeping drive axle tyre temperatures cooler in the heat,while complying with lower axle weight regulations,and better resistance to drive axles digging themselves into deep snow.In addition to less chance of jacknifing,than a 4 x 2 at least,under braking/engine braking. 
agree with cav551, yawn at Carryfast.
Cav
Are you saying the trailers are specced better because they’re only biaxle or because they don’t use super singles? I’ve never seen an American trailer up close let alone pulled one. I’m just interested to know what advantage they have over your average UK trailer.
Cheers
cav551:
The 6x4 units have probably got more to do with yee haa yankee image than anything else, the amount of bling being a case in point. North American, Australian and some European trailer specifications on the other hand just show up British equipment for what it is - come to think of it actually the entire British haulage industry for what it is, - a complete joke.
Are you joking? The USA is well behind the Uk when it comes to trailer spec. They’re only just coming to terms with Spring brake chambers and air suspension, never mind EBS or disk brakes.
There are plenty of youtube videos showing how to secure various loads onto North American and Australian flat trailers. What is immediately clear is that thought has gone into how to secure the load, the side rave design is totally different from UK trailers, it incorporates effective means of securing whatever is on the back, something which is rarely seen on our domestic products. This has been around for years in these markets, but the UK is only just beginning to even think about it- let alone see myopic penny pinching hauliers specify remotely similar equipment. Instead most rely on bog standard centre- roof- pole curtainsiders, with their pathetic internal straps, assuming that the thing is capable of transporting anything other than gas or liquid.
coiler:
Are you joking? The USA is well behind the Uk when it comes to trailer spec. They’re only just coming to terms with Spring brake chambers and air suspension, never mind EBS or disk brakes.
It’s probably fair to say that the Americans haven’t historically exactly been a bunch of backward no hopers in terms of road transport engineering or in fact any type of engineering.Having invented air brakes in the 19th century and made air brakes a standard requirement across the road transport scene from buses to heavy trucks in 1949.Spring brakes being part of that from at least the 1970’s with further developments of same by at least the 1990’s.
Disc brake development also being on a par with European development time lines not surprising with Bendix having merged with their Euro counterparts anyway.Everything else being a matter of understandable customer change in that regard.
Sorry carryfast, don’t agree with you there. Far from being an expert on North American trailers, when I went to Florida 10 years ago all the trailers I saw still had ratchet hand brakes, mechanical suspension and drum brakes. ROR had been taken over by Meritor, and they were pushing Spring brake chambers which we’d already had for ten years.
Roll forward to current times and SAF Holland have recently released advertising blurb on YouTube for their integral disk for trailers.
Carryfast:
It’s probably fair to say that the Americans haven’t historically exactly been a bunch of backward no hopers in terms of road transport engineering or in fact any type of engineering.
I do sometimes wonder how you come up with this stuff, not for too long though.
I have fond memories of taking weekend trips to the Big Apple when living in New Jersey. Sometimes I took the train, sometimes the bus. The bus was often a 2-stroke diesel. The year was 2002, not 1952.
milodon:
Carryfast:
It’s probably fair to say that the Americans haven’t historically exactly been a bunch of backward no hopers in terms of road transport engineering or in fact any type of engineering.I do sometimes wonder how you come up with this stuff, not for too long though.
I have fond memories of taking weekend trips to the Big Apple when living in New Jersey. Sometimes I took the train, sometimes the bus. The bus was often a 2-stroke diesel. The year was 2002, not 1952.
Which probably said more about the durability of the old Detroit motors and/or the buying habits of the bus operators.Bearing in mind the 60 series was available from the late 1980’s.Oh wait another piece of American junk to go with the N14. 
I think you’ll find that America adopted air suspension across the board much earlier than it became standard fitment in Europe, Britain especially.
6x4 is a bit of both CAV and Carryfast, image does play a part, but so do road and weather conditions.
The ratchet trailer brake handles you saw on your holiday in Florida were most likely the handles to release the pins on the sliding tandem axles on the trailers, they’re mostly air operated now, but there are still a few with manual release handles that look exactly like the old ratchet handbrakes and are positioned in the same place too.
Drum brakes ate still popular, especially on trailers, cost being a major drawback and when you take into account the 3:1 ratio of trailers to units and the fact that the larger fleets have 10,000 tractor units, you’re talking about a huge amount of money.
The other thing to consider is that a lot of trailers running around in the city are local work only, so they may well have been older stuff in semi retirement, which could explain the mechanical suspension.
If you were to go to Florida now you would see a huge difference in the trucks now, the days of the old classic long nose trucks are gone, everything is all aerodynamic now and under the skin the Volvo here is the same as the Volvo in Europe, the Mack range is all Volvo too in the same way Renault are. Kenworth and Peterbilt are Dafs and Freightliner and Western Star are Mercedes Benz. International is the odd one out and uses ■■■■■■■ engines, but that’s just a ■■■■■■■ version of the engines in every other truck on sale throughout the world.
When it comes to American trucks, never judge a book by its cover…
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Could it not just be demand? There are more operators speccing double drive over there so there is less demand for single drive units and therefore less incentive for manufacturers to develop and offer them to a USA market.
Its like with cars over here. Renault have recently launched their Laguna replacement in Europe but because of the lower demand for Saloon cars over here, the are not offering it in the UK, (which is a shame because its a nice looking motorcar, google the Renault Talisman). If a much lower percentage of the available market in the US is ordering 4x2 or even 6x2 units, it would actually be cheaper to not offer the lower capacity vehicles and simplify parts requirements at dealerships.
And how do you know they are double drive?
Might have 2 Rockwells but doesnt mean they have a prop or power divider fitted.
Probably cheaper to fit a second banjo axle than a beam unit and just not drive it.
Bking:
And how do you know they are double drive?
Might have 2 Rockwells but doesnt mean they have a prop or power divider fitted.
Probably cheaper to fit a second banjo axle than a beam unit and just not drive it.
I know because I see them every day, 99.% of North American trucks are 6x4.
There are a few 6x2s around and they’re mostly conversions that have the rear drive axle moved into the forward position and a trailer axle put in its place. A couple of friends have ordered them from the factory this way, but they are very rare.
The 6x2 is actually illegal in British Columbia and a lifting tag or midlift axle with the ability to be lifted on the move is illegal in Canada full stop, even on trailers. You can have them with exterior controls, but in some provinces they can only be lifted when the vehicle is completely empty.
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If European axle configuration is better than American why did I read that carriers go for 6th axle to be able to scale partial loads?
And while we on the subject can anybody explain to me need for trailer brake? In all years of driving I’ve never needed brakes released on dropped trailer.
The only time I’ve ever used the shunt valve on a trailer was when I ripped a red airline off doing a U turn in morning rush hour outside San Lorenzo customs in Rome and I GTFO the way before I got lynched or nicked.
I’m pretty sure that the designers never had that in mind when they came up with the idea, but apart from that incident I never had cause to use one.
The parking brake was useful for split coupling a trailer with a deep pin, I made use of that feature often.
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Shortcut:
If European axle configuration is better than American why did I read that carriers go for 6th axle to be able to scale partial loads?
And while we on the subject can anybody explain to me need for trailer brake? In all years of driving I’ve never needed brakes released on dropped trailer.
When you drop a trailer it is the tank pressure that holds the brakes on not the spring brakes.If you have a leak on the system then the spring brakes apply as the system pressure drops.When you pull the park button it dumps air out the chambers and applies the spring brakes.It stops you chasing the bloody things around the yard as was the case when you had single acting chambers and nobody could be arsed to apply the ratchet brake.
Once tank pressure had dropped on single acting chambers the brakes released.
Thats how a friend of mine got killed,nobodies fault ,the trailer rolled on coupling and he was at the back of it.Thats why you need an automatic system to put the brakes on weather there is air in the system or not or if somebody could be botherd to pull a brake button
Might save you or a friend of yours life.
For once I quite agree. If a trailer doesn’t have Spring brakes the handbrake must be applied when dropped otherwise there is a chance of no brakes and the trailer moving when reconnected. But if it has Spring brakes they will apply as the trailer loses air so it doesn’t matter about pulling the park brake button. Is that what you mean?
coiler:
For once I quite agree. If a trailer doesn’t have Spring brakes the handbrake must be applied when dropped otherwise there is a chance of no brakes and the trailer moving when reconnected. But if it has Spring brakes they will apply as the trailer loses air so it doesn’t matter about pulling the park brake button. Is that what you mean?
Thats exactly what I mean was once fitting a new wing to a trailer and an idiot decided to couple up to it. Without either tank air or spring brakes I would have been dead.Tell you something it ■■■■ me big time.7 tonne of trailer sat on your bollox really does put braking safety into perspective.And it only takes a moment to really screw things up.