Why is the unit on most car transporters a 6x2 with a light lift axle? If it all comes to less than 44T whats the point? Is the frame heavy? I’m working on an average weight of 1.2x11.
My last one, 6 axle, but full size mid lift as most Scanias are, tared in at just under 23 tons, heavier than most cos the skids (the ramps you pull out the back to run the cars up) on mine were fully hydraulic so another load of pipes and bodywork to weigh in.
The problem is cars are getting increasingly heavy and its a fine line for the body builders, the vehicles have to be strong enough seeing as they’ll probably serve on 2 or 3 tractors before a major refit, but too heavy and you’re defeating the game.
That small mid lift, unsteered too, probably saves half a ton on its own.
Bloody clever people design them though, the versatility is fantastic.
Disco 3 or Sport weighed nigh on 2.7 tons, carry 7 of those you’re getting close and larger cars are much heavier than 1.2 tons.
They are usually the worst of all worlds combination of being close coupled and semi trailer type design with set back trailer axles which means a lot of trailer nose weight.When that nose weight is added to the gross weight of the prime mover it’s probably going to be marginal on the drive axle weight capacity of the prime mover.Nothing to do with gross weight of the outfit. 
Carryfast:
They are usually the worst of all worlds combination of being close coupled and semi trailer type design with set back trailer axles which means a lot of trailer nose weight.When that nose weight is added to the gross weight of the prime mover it’s probably going to be marginal on the drive axle weight capacity of the prime mover.Nothing to do with gross weight of the outfit.
Not true, you have to physically load the front of the trailer deliberately, or rather avoid overloading the rear of the trailer to stop the tail wagging the dog.
The modern transporter is not a semi trailer, its a pure wagon and drag, the trailer hitch is standard W&D and set behind the drive axle, the trailer axles are behind the centre line of the trailer but not by much, you watch how unstable they are if a clot has messed up the loading and put too much to the rear of the trailer and not enough on the prime mover or front of the trailer.
I never had weighing problems for overall or axles, some did (those who couldn’t be arsed to load correctly to put some weight forward), you had to be careful though with 3 x Discos on the prime mover you could easily be up to gross weight for the tractor.
Jaysus H Christ Juddian. First rule of trucknet - don’t tell carryfast he is wrong!
Prepare for the inevitable onslaught of incomprehensible mumbo jumbo, supported by a thesis from Harold Wilson’s university days, to back up his point…
F-reds:
Jaysus H Christ Juddian. First rule of trucknet - don’t tell carryfast he is wrong!Prepare for the inevitable onslaught of incomprehensible mumbo jumbo, supported by a thesis from Harold Wilson’s university days, to back up his point…
Well he’s not really all that wrong, but i like living dangerously so said it… 
Could it be as simple as resale value of a 6x2 RHD unit compared to a 4x2 RHD unit?
muckles:
Could it be as simple as resale value of a 6x2 RHD unit compared to a 4x2 RHD unit?
Might be, but I think the low roof cab will let it down come resale time. 6x2s also cost more to run don’t they?
Juddian:
Carryfast:
They are usually the worst of all worlds combination of being close coupled and semi trailer type design with set back trailer axles which means a lot of trailer nose weight.When that nose weight is added to the gross weight of the prime mover it’s probably going to be marginal on the drive axle weight capacity of the prime mover.Nothing to do with gross weight of the outfit.Not true, you have to physically load the front of the trailer deliberately, or rather avoid overloading the rear of the trailer to stop the tail wagging the dog.
The modern transporter is not a semi trailer, its a pure wagon and drag, the trailer hitch is standard W&D and set behind the drive axle, the trailer axles are behind the centre line of the trailer but not by much, you watch how unstable they are if a clot has messed up the loading and put too much to the rear of the trailer and not enough on the prime mover or front of the trailer.
I never had weighing problems for overall or axles, some did (those who couldn’t be arsed to load correctly to put some weight forward), you had to be careful though with 3 x Discos on the prime mover you could easily be up to gross weight for the tractor.
It’s all about being able to carry whatever and with only two axles the tractor is going to reach its GVW long before the trailer. Add an axle to the unit and heavier vehicles can go on the tractor.
cav551:
Juddian:
Carryfast:
They are usually the worst of all worlds combination of being close coupled and semi trailer type design with set back trailer axles which means a lot of trailer nose weight.When that nose weight is added to the gross weight of the prime mover it’s probably going to be marginal on the drive axle weight capacity of the prime mover.Nothing to do with gross weight of the outfit.Not true, you have to physically load the front of the trailer deliberately, or rather avoid overloading the rear of the trailer to stop the tail wagging the dog.
The modern transporter is not a semi trailer, its a pure wagon and drag, the trailer hitch is standard W&D and set behind the drive axle, the trailer axles are behind the centre line of the trailer but not by much, you watch how unstable they are if a clot has messed up the loading and put too much to the rear of the trailer and not enough on the prime mover or front of the trailer.
I never had weighing problems for overall or axles, some did (those who couldn’t be arsed to load correctly to put some weight forward), you had to be careful though with 3 x Discos on the prime mover you could easily be up to gross weight for the tractor.
It’s all about being able to carry whatever and with only two axles the tractor is going to reach its GVW long before the trailer. Add an axle to the unit and heavier vehicles can go on the tractor.
While I can understand that it seems to be a contradiction because firstly there’s no way that it’s a ‘pure wagon and drag’ because that would be an A frame type.In which case the trailer imposes no weight on the prime mover whatsoever.
While there’s equally no doubt that the type of trailer design in question is closer to that of a typical semi trailer with set back axles and therefore a realatively high nose weight relative to its gross weight.Which as Juddian says is then coupled up to the prime mover with a coupling position ‘behind’ the drive axle.Which means that all of the trailer nose weight is carried on the drive axle, while also even lifting some off the steer axle and putting on the drive.
All of which suggest that the outfit would be over on it’s drive axle weight capacity before the gross weight/loading capacity of the prime mover is reached not vice versa.Which is a common well known flaw in the close coupled trailer design even in the case of centre trailer axle positioning.The obvious answer then being the use of a three axle prime mover to reduce the load on the drive axle.
Let’s take a typical car transporter load of 7 Land Rovers, carried on a drawbar transporter with a 6x2 unit.
A few years ago, a number of 4x2 units were still used pulling the same transporter bodywork as todays 6x2 units.
When they loaded at JLR, they were restricted to carrying 6 vehicles, not 7. The vehicle removed was the ‘peak’ car, the one over the cab. The lift axle is more important for the steer axle than the drive axle, as a car transporter puts a greater weight on the steer axle due to the presence of the ‘peak’ car. This is even more important at JLR, due to the health and safety requirement of driving not reversing this car, thus hanging the heaviest part of the car, the engine, over the front.
As Juddian rightly says, you want to place as much weight on the front of the trailer as you can. Failure to do so will result in you driving down the road admiring alternate sets of side marker lights… 
Lank:
Let’s take a typical car transporter load of 7 Land Rovers, carried on a drawbar transporter with a 6x2 unit.Failure to do so will result in you driving down the road admiring alternate sets of side marker lights…
Hah brilliant…
Lank:
Let’s take a typical car transporter load of 7 Land Rovers, carried on a drawbar transporter with a 6x2 unit.A few years ago, a number of 4x2 units were still used pulling the same transporter bodywork as todays 6x2 units.
When they loaded at JLR, they were restricted to carrying 6 vehicles, not 7. The vehicle removed was the ‘peak’ car, the one over the cab. The lift axle is more important for the steer axle than the drive axle, as a car transporter puts a greater weight on the steer axle due to the presence of the ‘peak’ car. This is even more important at JLR, due to the health and safety requirement of driving not reversing this car, thus hanging the heaviest part of the car, the engine, over the front.
That might make sense in the case of a rigid on its own but the laws of weight distribution change when you drop a bleedin great trailer nose weight behind the drive.At that point the drive axle not only remains subject to its original load but also that of the trailer nose weight and the weight which that nose weight is trying to lift ‘off of’ the steer using the drive as the pivot point.In which case it seems obvious that the idea of putting in the third axle is to firstly reduce the original drive axle loading and by doing so also moving some of the load that’s been taken ‘off’ the steer back ‘onto’ it and off of the drive.Which seems to be confirmed by the positioning of the third axle being put close ahead of the drive.Not the Chinese six type arrangement which is what would actually be needed ‘if’ the aim was to reduce steer axle loading.
Carry, there isn’t much weight imposed by a standard modern 3 axle trailer onto the towing hitch, indeed if empty putting one single standard car on the back of the trailer will reduce it to virtually balanced so little is imposed, and Lank is absolutely right about loading forward on the trailer whenever possible to stop the wags, if you are empty and have that one car on the back it makes the vehicle very uncomfortable to drive and you could easily induce the caravan shake if you drove it like a ■■■ like that.
There’s good reason Lohr put a half moon stabiliser in 'tween lorry and trailer, it works.
The trailer might look as if the wheels are well back, but you look again when its got three long cars with overhangs one piled on top of another hanging right off the back, wheels in the greedy bars, the middle one usually front facing out on a standard 11 plus type design.
One other reason for the 3 axle prime mover is stability, i found the most stable was the twin steer Scania, the Volvo FM 6x2 even with its non steer small mid could get right out of hand just by crossing the wear lines on a well worn motorway, and i followed a mate with a 4x2 FM Loaded with Landrovers who got the full sways on several times, how it didn’t roll i shall never know to this day, they got shut of it in the end.
Its the handling that makes the job tiring even just motorway driving, in an ordinary lorry you can sort of switch off, take your mind of it for a second with a carrier of the type we are discussing and you’re in the ■■■.
Juddian:
Lank:
Failure to do so will result in you driving down the road admiring alternate sets of side marker lights…Hah brilliant…
That’s the general issue applying to all the unfortunate drivers of the flawed close coupled trailer idea.Or overloaded drive axles when using the type of nose weights needed to cancel it out.
On that note that’s a ‘pure wagon and drag’ car transporter. 
2 easiest axles to overload on a modern 11+ car transporter are the steer and rear trailer axles. This is due to load configuration.
Am confused by Carrys idea that you would want to take weight off the lift axle and transfer it on to the steer axle…
Juddian:
Carry, there isn’t much weight imposed by a standard modern 3 axle trailer onto the towing hitch, indeed if empty putting one single standard car on the back of the trailer will reduce it to virtually balanced so little is imposed, and Lank is absolutely right about loading forward on the trailer whenever possible to stop the wags, if you are empty and have that one car on the back it makes the vehicle very uncomfortable to drive and you could easily induce the caravan shake if you drove it like a ■■■ like that.
There’s good reason Lohr put a half moon stabiliser in 'tween lorry and trailer, it works.The trailer might look as if the wheels are well back, but you look again when its got three long cars with overhangs one piled on top of another hanging right off the back, wheels in the greedy bars, the middle one usually front facing out on a standard 11 plus type design.
One other reason for the 3 axle prime mover is stability, i found the most stable was the twin steer Scania, the Volvo FM 6x2 even with its non steer small mid could get right out of hand just by crossing the wear lines on a well worn motorway, and i followed a mate with a 4x2 FM Loaded with Landrovers who got the full sways on several times, how it didn’t roll i shall never know to this day, they got shut of it in the end.
Its the handling that makes the job tiring even just motorway driving, in an ordinary lorry you can sort of switch off, take your mind of it for a second with a carrier of the type we are discussing and you’re in the ■■■.
That same flaw of a decent nose weight being needed to stabilise the outfit applies to all close couple types from car and caravan to max weight ‘drawbar’ outfits.While even at best that flaw is always there compared to the A frame type in terms of road manners.It’s just that load distribution limitations of car transporters probably magnifies those flaws.
The point being that in most cases the idea of a 6 wheeler close coupled drawbar prime mover is all about trying to deal with that conflict between trailer nose weight v drive axle loading.
Lank:
Am confused by Carrys idea that you would want to take weight off the lift axle and transfer it on to the steer axle…
No it’s using the third/ ‘lift axle’ to take the weight ‘off’ the ‘drive axle’.Which will also put some of the weight,lifted ‘off’ the steer and onto the drive by the trailer,back onto the steer as part of that.As I said close coupled trailers really are flawed pieces of junk.
You cant believe everything you read up on by Googling the info 