Nose weight on twin axle caravans

[Coops]

There is probably a simple answer to this, but if there is I don't know it!!

I see there is an article in this months C&CC mag on the subject of the importance of maintaining the correct nose weight. Fine on a single axle, but it has always seemed to me that twin axle caravans pre-determine a very narrow range of choice of nose weight, after which you are fighting the weight on one axle or the other. I have heard the theory that by having the front axle tyres a couple of pounds pressure more than the back axle tyres would have the effect of lightening the nose weight - is this a credible suggestion ? Is there anyone with an informed opinion of this problem ?

Les C.

 

[Lutz]

If you increase the pressure of the front pair over that of the rear ones you are transferring more load to the front tyres. In the extreme, this would turn a twin axle into a single axle with a redundant rear pair of wheels, with the result that the front pair is having to carry up to twice the design load. This could lead to premature tyre failure and is therefore potentially dangerous. The tyres should therefore always have the same tyre pressure.

 

[ShadySadie]

Of course you can't have different tyre pressures, in the event of an accident surely you could become uninsured if the tyres were under inflated.

What is the problem with nose weight?

Just move your load forward or back until you hit correct nose weight. I've towed our caravans single and twin solo when other half has been away working. Nose weight is easy to solve and has never been a problem.

 

[RogerL]

Of course you can't have different tyre pressures, in the event of an accident surely you could become uninsured if the tyres were under inflated.

What is the problem with nose weight?

Just move your load forward or back until you hit correct nose weight. I've towed our caravans single and twin solo when other half has been away working. Nose weight is easy to solve and has never been a problem.

Twin axle noseweight is difficult to measure accurately.

If you put heavy things like awning in the towcar, there's nothing to move around.

 

[Coops]

In my opinion, it is not possible to discuss achieving ideal nose weight on a single axle caravan in the same breath as discussing that on a twin axle.

Am I correct in thinking that the nose weight recommended by the manufacturer of the caravan is equivalent to the amount of nose weight that they have deliberately built into it?

If so, would it also be true to say therefore that, on a twin axle caravan it is only at that precise weight that the caravan is in equilibrium, with equal pressure on all four wheels, and that with traveling with less than the recommended nose weight, the front axle is loaded up, whilst conversely excess nose weight loads up the back axle ?

If these things are true, anyone traveling with as little as 1KG under or over the recommended nose weight is producing the exact scenario described by Lutz and Shady Sadie ON A TWIN AXLE.

The suggestion of moving stuff endlessly to the back of the caravan until nose weight is achieved (if ever !!) fills me with horror. Personally, all my heavy stuff goes into the 4WD except the tinned food, etc, which is stored smack over the axles.

After some years of contemplation of the problems with a twin axle I believe there are only two possible solutions to its precise nose weight. The first is to lower the nose of the caravan on the dolly wheel (whilst detached from the car) until the ideal weight is indicated on the measuring device, then fit a drop plate on your vehicle so that the tow ball matches that height precisely. (I suspect that this will probably result in a 'tail in the air' car/caravan combination that I think we all seek to avoid), or

Two - for the twin axles to be mounted on a bogey, with the chassis pivoting in the pitching plane, thus providing the ease of a single axle in achieving ideal nose weight. This must already be being done, as I'm sure I've seen pictures of triple axle caravans in America - fancy trying to get nose weight with one of them !!

Regards

Les C.

 

[Lutz]

It would be nice if the caravan manufacturers designed the caravan in such a way that the recommended noseweight is achieved without having to do anything. Unfortunately, based on various previous posts in this forum, this is not the case, particularly with UK manufacturers.

The scenario that I was describing, whereby one axle takes the full load and the other none would, of course represent the worst possible case. A difference of only 1kg from the recommended nose weight, as you describe, is certainly not going to produce such an extreme result (it would only be theoretically true if the caravan had no suspension and solid wheels).

As I pointed out in another post, the use of drop plates is only legal where the towbar manufacturer has provided for such an option and it is type approved. This rules out such an alternative where a twin axle is towed by a non-4x4. The use of drop plates to get the nose weight correct is therefore not realistic, quite apart from the fact that you may have problems with the jockey wheel bottoming out if you are too low. Besides, there is no guarantee that lowering the towball is actually going to lower the noseweight. With a single axle this is certainly not the case. With a twin, the effect of tipping the centre of gravity forward by lowering the front end could still be greater than the transfer of load from the rear to the front pair of wheels, so that it is impossible to generalise.

In principle, therefore, there is no other option but to adjust the noseweight in the same way as in the case of a single axle.

 

[ShadySadie]

We've had twin axle caravans for about 12 years now, I towed the first twin axle when before my husband as he was away working. Putting gauge in place and loading to suit was easy and always has been. We carry mainly the same supplies and personal equipment so it all lives in nose weight friendly location. Awning frame just rides mainly central when in the caravan.

Where "difficult" comes in is a mystery to us, may be you should chaps should leave loading to your women folk. Loading and using nose weight gauge may be more suited to a logical femail multi tasking brain.

My sister and I both tow twin axle caravans and we've had no problems with 6 different twin axle caravans between our families.

 

[Lutz]

I share your thoughts. I don't see why adjusting the noseweight should be any more difficult, either, although some caravans do seem to suffer from a less favourable ex-works condition than yours.

 

[ShadySadie]

Lunar, Elddis, Bailey and Bessacarr twins between our two families and they have been no problem.

We set tow hitch height and the gauge, hand brake off with wheels chocked on our level driveway and then lower steadies so they are just above the ground and retract the jockey wheel.

We then load accordingly just wedging a steady and adding the load and then checking the gauge. Once the initial nose weight is known it is not exactly rocket physics to work out where weight is needed! We tow at 60mph and often faster in France and have never had any balance/noseweight problems with a twin. An odd KG out has never been a problem as you say Lutz.

 

[spj]

I don't see why a twin is more difficult than a single, it pivots on two axles instead of one, a twin has softer suspension and more compliant tyres due to less weight per axle.

The length of the van will play a bigger part, the longer the van the bigger distance from axle(s) to the gas locker, so a bottle of gas 10 feet from the axle will take more to balance than a bottle 6 feet from an axle.

My car has a max nose weight of 135kg but the caravan is over this with a 13kg bottle, 6kg bottle, spare wheel, aquaroll, wastemaster, sat dish tripod, jack and waste pipes in the front locker, but rather than put the awning and generator in the back of the caravan (which are only taken a couple of times a year)I put them in the car with very little in the caravan, with the car heavy and the van light and with near 150kg nose weight it is level and very stable.

spj

 

[Lutz]

Agreed, spj, but you are in the lucky position to be able to go up to 135kg noseweight. There are lots of people who are limited to 75kg and, for them at least, it's not quite as easy. Basically, however, there is no difference in the method of adjusting the noseweight, whether single or twin.

 

[spj]

This is one advantage of towing with a 4x4, my ideal towcar would be something like an E class estate but with 4wd as we rally a lot on wet fields, a normall 4x4 is the only car that will do everything we want it to as an Audi A6 and Allroad is a little light.

spj.

 

[Lutz]

You must have a darned big caravan then if an Audi A6 Allroad doesn't meet your needs. Even in its most basic version it has a maximum permissible towload of 1900kg.

 

[spj]

I try to stay within recommendations, and 85% matched outfit will be more stable in heavy braking than a 100% outfit, also the Allroad at the time I bought my ML270 at just under 2 years old was more expensive and would have been a year older for the same money, also will the Allroad take near 150kg noseweight?

My money, my choice, it works for me.

spj.

 

[joeby]

the noseweight on my car is over 120 kg ,but the Alko chassis on my twin axle is a max of 100 kgs on the nose weight , so if i used the full nose weight of the car , would i not be breaking the law

 

[Lutz]

The short answer to your question, Joby, is 'yes'.

 

[Steve L]

Les, in answer to your question.

Lowering tyre perssures is not the way to create balance in a twin axle van for towing.

In modern vans the chassis is designed with the to axles independant of each other. So adopting the same method as single axle vans is the best way to tow.

Don't forget to use the lower limit of either hitch or car as your upper nose weight limit.

You do get quite a variation of nose weight with a modern twin axle arrangement as when going over bumps there is a lot of weight transfer from axle to axle.

I on the other hand, have a 25 year old twin axle van (Link 575) which has got linked axles. this system allows one wheel to rise up over the bump and by means of the mechanical link system it pushes the trailing axle down, creating very little weight transfer. So altering tyre pressures would have zero affect anyway.

The down side to my van is that I cannot raise the front end high enough to get the front set of wheels off the ground for easy manual handling, due to the suspension system.

Good job I'm good at reversing!!

Steve L.

 

[joeby]

The short answer to your question, Joby, is 'yes'.

i knew the answer Lutz ,i am just supprised no one has not picked up on the van with a nose weight of a 150 KGS