Why do some vans have twin axles and others single?

[Dustydog]

Back in the 70's one of the UK caravan manufacturers did have a a four wheel caravan with the forward axle having steering rather like the showmans caravans. Reversing is a real pain.

They never caught on.

Steptoe’s horse and cart managed 😜.Never saw him reverse 😉

 

[Hutch]

No not at all...quite interesting..

Never likely to be an issue for us.

Might be interesting to see a caravan with 4 wheels... 2 at front, two at the back. Someone will no doubt tell me why you can't 😉

I did see one parked up in a hotel car park in Switzerland, I think it was being used as an extra bedroom. steerable front axle.

 

[izzy]

We have a single axle smallish 2 berth with movers to get it up the drive, it is very twitchy to reverse with the car.
My son has a TA without movers and says it tows like a dream. Yes it is heavy to pitch by hand but he says that up to now he hasn't needed to and that if he does he will just get more hands on the job

 

[Lutz]

I do need to go as high as 145kg as 100kg is too low and the outfit becomes unstable. Our ALKO hitch is rated for up to 150kg and car is rated for 175kg. Our previous Lunar we were limited to 100kg although at 120kg they ride did feel more comfortable.

If you need to set the noseweight at 145 kg in order to get a stable outfit, there's something wrong somewhere. When I picked up my caravan new from the dealer without any gas bottles, spare wheel, EHU cable and other sundry items in the front locker, I towed it empty, probably just above the MIRO of 1450kg, about 150 miles with an estimated 25kg on the towbar. Admittedly I noticed a certain degree of nervousness, but I wouldn't have described it as unmanageable.

 

[Lutz]

Steptoe’s horse and cart managed 😜.Never saw him reverse 😉

Trucks towing trailers with a steered front axle are quite commonplace on the Continent. Reversing with such a configuration is one of the requirements for a CE driving licence.

Log Truck 360 Turn Around Above Dangerous Cliff Edge

 

[ProfJohnL]

We have a single axle smallish 2 berth with movers to get it up the drive, it is very twitchy to reverse with the car.
My son has a TA without movers and says it tows like a dream. Yes it is heavy to pitch by hand but he says that up to now he hasn't needed to and that if he does he will just get more hands on the job

This isn't surprising, the shorter the trailer/caravan, the more sensitive it is steering inputs when reversing. Longer trailers are easier.

 

[Buckman]

If you need to set the noseweight at 145 kg in order to get a stable outfit, there's something wrong somewhere. When I picked up my caravan new from the dealer without any gas bottles, spare wheel, EHU cable and other sundry items in the front locker, I towed it empty, probably just above the MIRO of 1450kg, about 150 miles with an estimated 25kg on the towbar. Admittedly I noticed a certain degree of nervousness, but I wouldn't have described it as unmanageable.

Not sure why you think that as the maximum nose weight for the hitch is 150kg? At 145kg I have a nice stable comfortable tow. Most people with the same type of caravan also have their nose weight at about 140kg.

 

[GaryB]

That's great, but the point is the design of caravan that suits your needs does not have to be a TA, another model could offer the same layout and space but only be an SA

The size and layout is not directly linked to the number of axles or vice versa.

In our case we went from a 2018 Sprite Quattro EB (twin axle) to a 2022 Sprite Major EB (single axle), both have pretty much the same layout (mid-bathroom, end bedroom) but obviously a shorter body length. Yes, we do notice the reduction in interior space but with our daughter at university and not coming away with us quite as often, it's not too bad.

 

[Lutz]

Not sure why you think that as the maximum nose weight for the hitch is 150kg? At 145kg I have a nice stable comfortable tow. Most people with the same type of caravan also have their nose weight at about 140kg.

I just have difficulty in understanding why some people feel the need for 145 kg noseweight when others are quite comfortable with half that, despite the same size of caravan. Somehow it doesn’t seem logical unless there are other factors influencing the result.

 

[Ukdave2002]

It could be inconsistent methods of measuring nose weight, I know someone who used to but a block of wood under his gauge when on soft ground, he was blissfully unaware that this would alter the reading, likewise if a towball is to high or low , the effective nose weight will be different.

 

[ProfJohnL]

It could be inconsistent methods of measuring nose weight, I know someone who used to but a block of wood under his gauge when on soft ground, he was blissfully unaware that this would alter the reading, likewise if a towball is to high or low , the effective nose weight will be different.

I'm not sure why you think the hardness of the ground affects the reading? Provided the measuring device is not sinking into the ground the reading should indicate the load applied.

Or were you telling us, becasue the measuring device was sinking into the ground he used block of wood to support the measuring device, which raised it, and that also raises the height of the hitch, which changes the reading - which would cause errors?

 

[Ukdave2002]

I should have been clearer sorry, was pointing out that if using the telescopic nose weight gauge, the displayed load will vary if the height of the gauge is altered, i.e. by raising it on a piece of wood.

 

[ProfJohnL]

I should have been clearer sorry, was pointing out that if using the telescopic nose weight gauge, the displayed load will vary if the height of the gauge is altered, i.e. by raising it on a piece of wood.

Very true and it's why I never suggest buying a dedicated gauge, when you can be use bathroom scales and be more consistent and probably accurate.

 

[Buckman]

I should have been clearer sorry, was pointing out that if using the telescopic nose weight gauge, the displayed load will vary if the height of the gauge is altered, i.e. by raising it on a piece of wood.

Why would you want to raise it if you are on level ground. The Milenco is probably far more accurate than ny bathroom scales and the faff that goes about using those scales. Who cares whether nose weight is out by a couple of kgs?

I just have difficulty in understanding why some people feel the need for 145 kg noseweight when others are quite comfortable with half that, despite the same size of caravan. Somehow it doesn’t seem logical unless there are other factors influencing the result.

Do they have E&P self level,ling fitted. A light nose weight on a caravan weighing 2000kg could end up with the tail wagging the dog. If you want to tow the same caravan with a lighter nose weight that is your prerogative and good luck to you.

 

[Dustydog]

Don’t forget measuring a TA NL is totally different from an SA .
Reich specifically sell different gauges for the two.
The final height of the hitch resting on the tow ball must be taken into account. The TA is not straight forward. Somewhere years ago was a thread which dealt with the subject in great detail.
I’m not sure how Buckman measures his NL but it is not as simple as a SA.

 

[otherclive]

Don’t forget measuring a TA NL is totally different from an SA .
Reich specifically sell different gauges for the two.
The final height of the hitch resting on the tow ball must be taken into account. The TA is not straight forward. Somewhere years ago was a thread which dealt with the subject in great detail.
I’m not sure how Buckman measures his NL but it is not as simple as a SA.

Post #8 of the link below is quite mind boggling along with some of the others too. But the tread does cover the idiosyncrasies of TA compared to SA.

I will probably be locked on account of the reference being quite (sic) ancient. 😱

Noseweight checking

To make life a little easier when checking my caravan's noseweight I came up with the following idea, but are my thoughts/calculations correct. Although I normally use a noseweight gauge these aren't particularly accurate. Using bathroom scales is more accurate but involves having a piece of...

forums.practicalcaravan.com

 

[RogerL]

Don’t forget measuring a TA NL is totally different from an SA .
Reich specifically sell different gauges for the two.
The final height of the hitch resting on the tow ball must be taken into account. The TA is not straight forward. Somewhere years ago was a thread which dealt with the subject in great detail.
I’m not sure how Buckman measures his NL but it is not as simple as a SA.

For both single and twin axle, the noseweight should be measured with the hitch at laden towball height for maximum accuracy.

 

[Buckman]

For both single and twin axle, the noseweight should be measured with the hitch at laden towball height for maximum accuracy.

Would it make any difference if the vehicle has air suspension which automatically sets the height of the car?

 

[Dustydog]

For both single and twin axle, the noseweight should be measured with the hitch at laden towball height for maximum accuracy.

Absolutely agree. But more difficult with the TA . Variations creep in by the mm

 

[RogerL]

Would it make any difference if the vehicle has air suspension which automatically sets the height of the car?

You'd need to use the height of the towball in the laden condition, regardless of suspension type - taking into account that not all automatic systems are instant.

 

[ProfJohnL]

Absolutely agree. But more difficult with the TA . Variations creep in by the mm

Why is it more difficult with a TA?

Provided you take the measurement in the way I have been at pains to point out over the years, the most significant variables are accounted for.

Why should variations creep in? Can you explain please?

 

[Buckman]

Absolutely agree. But more difficult with the TA . Variations creep in by the mm

As said who cares about a couple of kgs here or there unless you are carrying it. Anyway I doubt very much if there is any legislation regarding the nose weight of any caravan. Maybe not even the tow bar? Legislation would apply to the weight on the rear axle and that weight probably governs the maximum tongue weight on the tow bar / ball?

 

[ProfJohnL]

Whilst there is no statutory limits set for nose loading or tow bar S values, exceeding the manufacturers specifications might be construed as a dangerous loading or being unroadworthy.

The UK still applies the same requirements on motor manufacturers as the EU about how the maximum towed weight for a vehicle is assessed. The tow bars capability has to be capable of accepting a noseload of a minimum of 4% of the maximum towed weight, and that also has to be compatible with all the other limits for the vehicles.

Its more complex than the nose load limit being determined just by the axle loads. In reality both the axle limits and the nose load limits will be outputs rather than inputs to a far more involved set of considerations.

 

[Lutz]

Do they have E&P self level,ling fitted. A light nose weight on a caravan weighing 2000kg could end up with the tail wagging the dog. If you want to tow the same caravan with a lighter nose weight that is your prerogative and good luck to you.

I don’t quite see what E&P self levelling has got to do with it. Noseweight is noseweight. So long as it’s always measured under the same conditions as when hooked up to the car it doesn’t make any difference.
I wasn’t advocating a low noseweight. I was only questioning why it needs to be as high as you suggest if everything else is set up properly. The regulations state that the manufacturer must guarantee a minimum noseweight of at least 4% of the weight of the trailer. Consequently, it must be possible to ensure adequately safe conditions when towing a 2000 kg caravan if the noseweight is 80kg. It should not be necessary to have 145kg on the towball.

 

[Notmyvan]

Sitting here watching vans arrive on site most of which are twice the length as ours. My wife asked the question, why do some have twin axles and others single when they appear to be roughly the same length.

So, why?

Its to do with tyres. Tyres on larger single axle caravans can only just carry the weight which the tyres were designed for, so if they make a caravan which is slightly heavier they have to go to a twin axle.
Which is why what you can carry in a single axle caravan is so low.