Caravan Stability

[David_from_Ashby]

The point of nose weight being as high as possible within the design limits of the caravan hitch and the car's towbar, is to add weight to the rear axle of the tow car.

The rear axle of the tow car has to be secure on the road so that it can resist the lateral forces transmitted through the towbar that are present as the caravan becomes unstable.

Rob can make his outfit more stable by adding heavy items to the rear of his towcar with a compensatory increase in rear tyre pressure.

Hi All

I tow a 1300kg Compass Corona behind a new shape Honda CR/V, this has always been a bit unstable at higher speed (in France I should add) and occasionally a bit "wobbly" on UK motorways, particularly when overtaking/being overtaken by coaches.

I have always been careful with loading and nose weights and also with spraying the stabiliser and tow hitch with brake degreaser before every journey.

Out of curiosity I replaced the stabiliser friction pads because I suspected them of being the originals (8 years old now) and what a difference it has made, the van is now much more stable, and hardly twitches when being passed by coaches now. Interestingly the old pads had a glazed and encrusted surface that looked highly contaminated with something...far from being friction pads!

FWIW

David

 

[Paul_5064559]

If I were considering investing in a touring caravan, a look at this thread would soon change my mind double quick!

 

[ShadySadie]

If a new caravanner is going to venture out on the road without previously researching and finding about speed limits for towing or what is legal when towing I doubt that they will be influenced by the too regular points made here about speed.

Caravan stability!

I'm more concerned about the 'stability' of some drivers here ;+)

 

[billy2]

Ray,

I most certainly have not rubbished your comment or the fact that both Bailey and Alko expect a level or nose down tow. If that is how they have designed their product to conform with the EU regs then so be it.

But why is it logical to tow with the nose down or level or more to the point why is it illogical to tow with the nose up?

There are many camping trailers that are very nose up.

There are many travellers who tow nose up and not all with lorries. They tow more miles in a year than most people tow in a lifetime.They usually get where they are going .

 

[billy2]

Euro,

I stand by that statement and I challenge you to explain how speeding during an overtaking or any other manoeuvre is ever justifiable.

If you would need to speed to complete the manoeuvre then it is not appropriate to consider the action.

Anyone who considers themselves above the law and free to break speed limits (in any country) has suspect driving standards.

Please note I am not equating speeding as necessarily being unsafe, just illegal.

Speed limits are there for a reason although some dont think so unfortunately they are the ones who think they are above the law.You see them every day it is sad that some of them have got caravans on the back they get a powerfull car hitch up the caravan aqnd take off as though they only have 5 minutes to live well one day perhaps they will its unfortunate that sometimes inocent people get hurt as well but i am with you on this one there is never a reason to speed.And as for overtaking a line of trucks aproaching the end of a dual carraige way lunacy should be baned for life give us law abiding caravaners a bad name.

 

[billy2]

Hello Euro,

Please reference any official document from the police or Govt departments or the IAM, ROSPA or any other official body where speeding by members of the public is condoned or authorised under any circumstances.

If you find yourself in a situation that you think needs speeding to correct it then you should not have placed yourself in that position in the first place.

hear hear

 

[billy2]

After reading through this topic it seems to me there is a couple of people posting on hear who 6 points and a

 

[xtrailman]

billy

When i had my snake, i did exactly what you said, what i have read many years ago.

I lifted off the accelerator, and did not break, after an age, control was regained.

However afterwards and since, i have always though maybe a very light foot on the brakes may have helped?

Interestingly, the ALKO system works by appling some brake pressure to the van brakes, also ESP in a round about way also applies brake pressure, but potentially to individual wheels.

What effect does a vacuum have on stability?

 

[Guest]

Where are all the people who are suggesting speeding on this section?

The fact that the odd few mph over the limit may be the best option in some rare problem moments is not suggesting that caravanners head off at 70mph plus as soon as they hit the M5.

Most cars could break towing speed limits, no matter what car anyone drives I doubt that many hack it down the motorway van in tow like Jenson Button aiming for top spot on the podium.

Some of the worst speed offenders we see are driving a family favourite tug and try and race off in to hills or shoot

along level roads to make up for time lost on hills.

 

[billy2]

Hi Ray you did exactly the right thing and yes if it was possible for you to have braked the van alone that would help as the new ATC system does now .If it happens again try to resist the temptation to brake,its hard i know but keep your speed to sensible levels especialy down hill when the van is pushing the car and i am sure your caravaning experiances will be fine.

 

[billy2]

billy

When i had my snake, i did exactly what you said, what i have read many years ago.

I lifted off the accelerator, and did not break, after an age, control was regained.

However afterwards and since, i have always though maybe a very light foot on the brakes may have helped?

Interestingly, the ALKO system works by appling some brake pressure to the van brakes, also ESP in a round about way also applies brake pressure, but potentially to individual wheels.

What effect does a vacuum have on stability?

With a wedge of air traped between the car and van (although larger 4x4s and transit type vans are more prone) going the same speed as you can cause a vacume .Sudenly you loose the preasure on the front of your van and it can cause a snake as the preasure comes off the towhitch .Older vans are more prone than the newer AL-KO hitch type.But the chances do increase as your speed increases but the main reasons realy are down to inproper loading.

 

[Gafferbill]

The caravan should not be pushing the car when travelling down hill as the overrun brakes on the caravan, if adjusted properly, will prevent this pushing rising to a significant level.

The alko Atc system uses braking to control snaking as a primary function, not to slow the outfit down.

Under normal braking, an articulated LGV has a brake bias where the trailer undertakes most of the braking.

This set up has been found to greatly increase the artics ability to stay in a straight line..an anti jack-knife system.

In practice the trailer is pulling at the tractor unit.

Alko have adapted this knowledge with their system, where applying the caravan brakes, pulls the outfit back into line and prevents the snake developing.

The caravan is pulling at the tow car.

 

[xtrailman]

I seem to recall the ATC function gives light braking only, i wonder should if it malfunctions and applies the brakes fully, whether this could rip the towbar off, or otherwise damage the rear of the cars mountings?

Just a thought

 

[xtrailman]

We now have three options now for you Rob.

Should the extra nose weight fail.

option two, fit ATC

option three, fit dampers.

Should all three fail, buy another van!

 

[Lutz]

I have had a LEAS electronic stabiliser on my caravan for the past 5 years (it works on the same principle as the AlKo ATC) and never had an issue with the brakes inadvertently coming hard on. In fact, the system is fail safe, so that full braking performance is not possible even if something went wrong.

That said, a towbar must be able to take the load of a caravan with the brakes fully applied without any damage to car or towbar.

 

[billy2]

Gafferbill

For the same reason your brakes dont come on when you reverse is the same reason you would not get a braking affect when caravan is pushing going down hill DONT COAST are the key words try to keep some power on .You will find under light braking no braking efect is felt by the caravan brakes as a certain amount of the preasure is absorbed by the damper.

 

[billy2]

The caravan should not be pushing the car when travelling down hill as the overrun brakes on the caravan, if adjusted properly, will prevent this pushing rising to a significant level.

The alko Atc system uses braking to control snaking as a primary function, not to slow the outfit down.

Under normal braking, an articulated LGV has a brake bias where the trailer undertakes most of the braking.

This set up has been found to greatly increase the artics ability to stay in a straight line..an anti jack-knife system.

In practice the trailer is pulling at the tractor unit.

Alko have adapted this knowledge with their system, where applying the caravan brakes, pulls the outfit back into line and prevents the snake developing.

The caravan is pulling at the tow car.

The braking affect of the ATC would not be felt by the tow car as it happens so fast but enough to put you back in a straight line without any slowing you would have a rather jerky journey if this was the case soon upset the other half.

The trailore brakes on LGVS are yes designed to come on first as you say it helps pull everything back into line same as you apply your bike back brake first not to stop you snaking but to stop you going over the handlebars.

 

[Lutz]

I'm sorry but I don't agree at all with the previous post. Whenever I have experienced 'twitchiness' on downhill stretches I have always regained stability by applying the brakes. This deploys the caravan's overrun brakes much the same as the AlKo ATC. Cars fitted with ESP+ and TSP (Trailer Stability Program) do the same, but automatically.

 

[billy2]

I'm sorry but I don't agree at all with the previous post. Whenever I have experienced 'twitchiness' on downhill stretches I have always regained stability by applying the brakes. This deploys the caravan's overrun brakes much the same as the AlKo ATC. Cars fitted with ESP+ and TSP (Trailer Stability Program) do the same, but automatically.

Lutz

Dont be sorry for not agreeing if we all agreed there would be no point in having forums .You are correct in what you say as long as enough force is applied when you brake to the tow hitch activateing the overrun brake yes it will have a stabalising effect on your van.As with all driving some people are light footed some are lead footed it would probably work better for the lead footed among us .

 

[Gafferbill]

http://www.al-ko.co.uk/alko-Trailer.htm
... this link shows that the system works by activating the caravan brakes ONLY .. The caravan is pulling at the tow car.

Have a look at the movie!

http://www.al-ko.co.uk/edit/files/support/BrakingOperation.pdf
.. this link shows that the overrun brakes on the caravan will prevent the caravan pushing the car down hill to any extent, as the brakes on the caravan WILL be applied.

It also shows how the act of reversing the caravan collapses the brake mechanism in the drum to allow the caravan to move backwards.

The wheel has to rotate in reverse for this to happen.

Billy posts..

"For the same reason your brakes don't come on when you reverse is the same reason you would not get a braking affect when caravan is pushing going down hill"

I do not think the wheel will rotate in reverse when you are going down hill at speed!!!

 

[billy2]

Gaferbill

Of course you are spot on about the brakes hence the problem with trying to apply the handbrake when van going backwards (seen that a few times).

Still working on a way to get them wheels to go in reverse when going downhill at speed not come up with anything yet.

By the way thanks for the movie.

 

[billy2]

The point of nose weight being as high as possible within the design limits of the caravan hitch and the car's towbar, is to add weight to the rear axle of the tow car.

The rear axle of the tow car has to be secure on the road so that it can resist the lateral forces transmitted through the towbar that are present as the caravan becomes unstable.

Rob can make his outfit more stable by adding heavy items to the rear of his towcar with a compensatory increase in rear tyre pressure.

Gafferbill

It may make the rear axle adere more to the road by placing heavy items towards the rear of the towcar.But the one thing missing is most modern towcars are front wheel drive putting more weight in the rear will only give the front brive wheels less grip which could make then unstable when cornering.As a point of interest i used to load heavy stuff awning chairs cool boxes full of the golden elixia wheel clamps and anything else i could get in, the car in question was a Mitsubishi Shogun rear wheel drive or 4x4 and very little drop in suspension height even with van on.But wouldnt advise same for front wheel drive car.

 

[billy2]

If I were considering investing in a touring caravan, a look at this thread would soon change my mind double quick!

Hi Paul

They are not all like this its just a certain click of know all know nothing who like to argue among themeselves if they knew as much as they think they do they would be working for PC.If you follow them through the topics they keep on popping up think its something to do with an under developed thyroid or something not quite developed right but you have a laugh.