Twin Axle Pros adn Cons????

[steven_374420387]

Hi, we had ordered a Lunar 09 534 fixed bed 21ft single axle, but having last minute jitters and considering the Lunar 09 Delta RS 26FT twin axle....

Putting a side the extra benefits of the fittings and layout...

What are the benefits or disadvantages of a Twin Axle??

We are new to caravanning and have a Kia Sorento 2.5 diesel manual so should be ok from that point of view...

Any advice please?

Thanks

Steven

 

[JohnnyV]

Hi Steven,

Have just started using our new Lunar Delta TL T/A, having previously towed my Daughters single axle Abbey.

From the towing aspect have noticed no difference in terms of ease or manouverability, however the T/A does have a slight tendancy to 'pitch' up and down which is noticable particularly on a bumpy road - does help having the nosewight correct (had to phone Lunar to get this - they advised 87kg).

One thing you do need to get right is lining up the ball/hitch when hitching up, you can't simply pivot the van on the axle by hand as you would with a S/A.

Other than these two items I don't find anything else to really be any different - obviously the T/A will cost you 4xtyres insted of two when you go to replace them and I understand from reading some other threads that some small sites don't like T/A's as they are inclined to tear up the grass if turned sharply.

On balance I think the benefits outweigh the negatives but each to their own!

Regards

Jon

 

[MikeMc]

The difference is about 5 foot. But seriously I find a twin tows a lot easier but is hard to push around so a mover is often required. Never had any problem getting onto sites but I have read that others have.

Mike Mc

 

[DianneT]

Have had an 8 metre twin axle for 3 years now been all over Europe 11 countries and have never been refused a place or at CC CL's in the UK.

We find as easy to tow as the single axle we had previously. We too have Kia Sorrento and no problems with that either.

 

[Steve L]

Hi Steven.

I have towed trailers both single and twin axle for 33 years.

You are quite right to say that your tow tug is capable for both vans.

Twin axle vans are more stable by virtue of the fact that you have four wheels aligned to flow in a straight line. Where as, a single axle van does tend to pivot (sway) a little easier as it pivots more freely at the tow ball. However a single axle van correctly loaded and I would suggest loaded to a minimum of 75Kgs nose weight should tow fine.

As already mentioned, you will need to be accurate at backing up to the hitch as usually you only have about an inch or so of persuassion available sideways to hook up.

One thing you will notice more on a twin axle van is the tendancey to pitch up and down over a bumpy road. This is due to the fact that you have independantly sprung axles, which means that the nose weight increases/decreases as you traverse a speed bump for instance.

One last area where a single might suffer worse is in a cross wind, and especially one where you have 10ft of overhang behind the axle. You might need to adjust your road speed downwards a little on a windy day and just be a bit more alert of your surrounding building/hill profiles, also going over via ducts and passing lorries and coaches.

You will also find a single axle van easier to move by hand. Also with a twin axle it is more prefferable that you are able to reverse proficiently. Which is not to say that any person who tows shouldn't be able to reverse their outfit, after all one needs to be capable of towing in any direction.

Over all though a single axle van is just as livable in as a twin axle, so I would say it is more down to personal choice.

Regards.

Steve L.

 

[Steve L]

By the way Steven.

I tow a 2005 Abbey 540SE single axle behind a 1998 2Ltr Renault Laguna estate with no trouble despite it being 100% of the tow cars capacity to tow.

ATB Steve L.

 

[Lutz]

I would agree with Steve that it's a swings and roundabouts situation. Both have their own advantages and disadvantages, so it's up to your own priorities, but as I mentioned before, once you've decided on size and layout, you probably won't have much of a choice between single and twin axle, anyway.

 

[Guest]

Steve's point re pitching. I'm not convinced on that one. We've found that on bumpy roads the twins seems to run better as the two axles nataraly try and keep the caravan level. I've had far worse pitching problems in the past with single axle caravans with nose weight correct.

But we do have better cars these days with superior suspension. May be Steve's pitching has more to do with car suspension. Twins run lower tyre pressures and I'm sure this helps give a better towing experience as well.

 

[Lutz]

Maybe the single axle caravan that you experienced pitching with was shorter than the twin? I would expect that on a strict size for size comparison, a single should in fact be slightly less susceptible to pitching, as Steve has already suggested.

 

[ProfJohnL]

I have also experienced pitching motion form a twin axle trailer. but only when I collected the trailer and it was empty, the nose load changes quite dramatically when the trailer goes over a hump and you can feel the change in load on the hitch. This could be quite disconcerting and some people may begin to feel motion sickness.

The solution is to ensure the nose load is set up properly and subsequently the trailer has behaved impeccably. It still produces a different feel compared to SA trailer but nothing serious.

 

[Guest]

I've towed a fair number of caravans quite a few trailers and horse box's.

I'm mystified by these posts. I guess I must have seen thousands of caravans, and pitching as in nose going up and down is something I associate as a clear problem with single axle trailers. Wth some road conditions our twins will of course pitch, but the up and down pitching motion is sooner over than a single to me. Must be doing something wrong I guess.

 

[Lutz]

I would suggest that pitching is dependent more on length of the trailer/caravan than whether it has one or two axles. Because of the higher moment of inertia of a long caravan, it will pitch less than a short one. An extreme example are the very long trailers that are used to transport gliders. These are almost exclusively single axle.

 

[Steve L]

Now then euro.

The pitching I'm on about is exactly what John has described. You do get a fair bit of weight transfer as each axle negotiates the bump. This is probably more accentuated when using a car for towing a twin axle as the cars tend to be softer sprung.

Most 4X4's would not exhibit this characteristic as they have much harder suspension. I found that our Ifor Williams trailer had to have the full 3500kg gross weight before it became noticable behind our Diahatsu F70.

Regards.

Steve L.

 

[ProfJohnL]

Clearly what I experienced must have had some motion associated with it but in reality it was more like a double thump on the tow hitch, high acceleration but a only a small movement.

 

[Gafferbill]

John L and others are experiencing a type of pitching on TA caravans that is simply not present on SA caravans.

That is where the surface is uneven. hump or bump.crest or dip.. the TA caravan can alter it's nose weight to a greater variation than a SA.

This is because the fulcrum or balance point can move on a TA whereas it never moves on a SA.

E.g. if the first axle encounters a rise in surface, weight will shift from the second axle to the first and the fulcrum will move towards the first and weight we be taken from the nose weight.

In a dip the opposite happens and the nose weight increases.

Steve L is scientifically correct.

One aspect that has been mentioned is that this might be the reason for some TA caravans becoming detached from the towing vehicle.

If the front axle is taking all the weight due to hump. rise .crest it will become the fulcrum and depending on the loading of the caravan the nose weight could become negative.

The hitch should still hold. but there has been cases where it has not for whatever reason.

 

[ProfJohnL]

I concur with Gafferbill completely, I would also add that the effect is speed dependant, and it is why setting the nose load correctly and towards the top of the available range is more important with TA compared to SA's