Double axle caravans
Thinking of changing to a double axle van - are there any tricks to adjusting the noseweight or does the double axle resolve that problem?
I guess that the double axle will reduce the simple balance situation that exists with a single axle, but is it usually necessary to adjust the tow ball height to match the van rather than to adjust the balance of the van? I ask because a towing hitch that is too high will be trying to tip the van onto the back wheels.
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Regulations state how high the towball shall be and there is normally (offroad vehicles excepted) no way of adjusting that height.
It is important that the noseweight is set an adequate level, regardless of whether the trailer is a single or a twin axle. Just below the lower of the two plated figures for the towbar and trailer is normally the target that one should aim for.
Consequently, when towing, the rear wheels of a twin axle will always be carrying a slightly higher load than the front pair.
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The best way to attain the correct nose weight is just a balancing act of where to position things inside the caravan, safely, for towing. We always like our noseweight to measure around 100kgs (the maximum limit for both our car's tow ball and the caravan hitch), and it's never been a problem to reach that. It may be different for you depending on your towing vehicle and caravan layout.
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Balancing a twin axle is just the same as a single axle, yes it is just as easy to get a nose weight that is too much, but mine does not seem as sensitive to noseweeight variance and tows well with a nose weight anywhere between 80kg & 100kg. Although it can be a challange to get it that low.
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I don't see that!
When the caravan is level and set up for 0 nose weight each axle would be carrying the same load and the centre of gravity would be between the two wheels (caravan balanced on it's axles! = no jockey wheel needed).
As the caravan is loaded to generate a nose weight the centre of gravity moves forward. If the hitch is then allowed to move down on to a tow ball the caravan adopts a slight nose down attitude and to achieve this the front axle suspension compresses (takes more load) and the rear axle suspension is extended (taking less load).
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I don't understand the concept of "applying" a nose weight, the nose weight is the amount of weight the nose exerts when the caravan is loaded.
In an ideal world we would tow level with equal load on each axle.
I think it will be standing level. the suspension units (4) are the same and bolted to a solid chassis rail, the wheels (4) are the same, tyre pressures are the same. If the centre of gravity is exactly half way between the wheels how would it not be level.
As the caravan is loaded with weight towards the front, the centre of gravity moves forward. If the centre of gravity moves forward the caravan must adopt a nose down attitude, it can only adopt a nose down attitude by compressing the front suspension more than the rear, hence my original assertion that the front axle is taking more load than the rear if the caravan is nose down.
In the above scenario there will however be zero nose weight (nose hanging in free space) until the caravan reaches tipping point, this happens when the centre of gravity moves forward of the front wheels, at this point the nose will crash to the ground unless something stops it. Ideally that something is a nose weight scales so that you can carry on loading the caravan until the nose weighs 100kg (or as required).
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It would be pure coincidence if the caravan were standing level when ready to be hitched up to the car and even more so when it is actually attached. Differences in loading conditions in the car and the caravan result in different standing heights and consequently different attitudes of both car and caravan. There is no reason why both should be level. Production tolerances in the suspension units also have an effect so that even when standing on its own and level, the axle loads of a twin axle caravan are unlikely to be the same.
It would also be pure coincidence if the noseweight were at the level required after initial loading of the caravan without some need to jiggle around with the load to get it right.
For that reason the axle loads on a twin axle will never be the same.
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The other thing to point out is to be aware that dips and humps in the road cause the nose of the a frame to pitch up and down as the pair of axles follow the topography. This can be quite uncomfortable on some roads, especially if your caravan wheels are following, or weaving , following longitudinal dips in the road caused by Lorry traffic.
Srgds
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My pal who has a TA Sterling asked to borrow my Milenco noseweight gauge. When his van was loaded as he normally did. The Gauge showed 150kg, much to his amazement!!!!
Some judicious adjustment of materials about the TAs and we managed to get an acceptable 80kg on the nose. He is away atm so will check on performance on his return!
Imo there has to be a sensible nose-weight or the tail will wag the dog. To have the nose-weight as a negative would be tending to disconnect the outfit - not a good idea.
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Is it Bull? (wrong) If you think so it would be more useful to say why you disagree.
May be too wordy for some but I thought it was an interesting discussion on the axle load distribution of twin axle caravans and the assertion made that the rear axle would be carrying more load when towing.
Level caravan (however unlikely) = equal axle load, Nose down attitude very likely/desirable when towing = more load on Front axle than the rear.
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Level caravan doesn't necessarily mean that the axle load is equal. It all depends on how the suspension is set up and on the spring rate production tolerances.
Also, why should a nose down attitude be any more desirable than a level one, or even a slightly nose up one? Standing height tolerances of both car and caravan can, under adverse conditions, result in a slight nose up condition even though all dimensions are within those specified in the regulations.
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Stephen P You are absolutely correct in your assumptions - a twin axle is no different from a single when it comes to nose weight. You must always have nose weight bias regardless of what axle configuration you have. The axles will adjust to marginal height differences. When you load the van check the the nose with a scale try to get it tto near the maximum the tow bar allows. On a caravan with an AlKO chassis the suspension is not compensated between the two axles therefore the front will invariably always have more weight on it since it starts to compress before the rear and the rear loses some of the load ( you can easily check this by using a weight bar to see how much difference there is. Axles with a compensated system will ensure that the load is equal and this does mean tyre wear and braking is better balanced. Alas this does not apply to the former. There is a small advantage though in that your mover will work much better when turning since the rear axle will not resist as much. Don't be misled by height adjustments on the nose - if it is too high then you are simply lifting the front axles off the load but you still have your positive load on the nose - you must still ensure it is not over the limit and don't forget you are trying to lift the weight of the front axle unsprung weight, it is better to have a slightly down position on the nose ie low on the height , the reason for this is that any pitch will always push downwards on the tow car, however, braking torque will tend to push down on the nose so not a serious problem.
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When I first started towing our twin axle, I loaded it to achieve a 120kg noseweight which is within limits of the Winterhoff hitch and the limit of the car (150kg on a Range Rover Sport)
The car has air suspension so after connecting the caravan and starting the car, the rear would rise to the level predetermined by the level sensors which is the same as if the car is solo.
However, due to the height of the fixed towbar, despite the noseweight and the air suspension, the attitude of the caravan was slightly nose down and you could visibly see the tyre deflection and position of the front axle wheels versus the rear axle wheels, that the front caravan wheels were carrying a greater load.
Towing like this was ok but there was quite a bit of pitching over bumps in the road.
I purchased a GAP diagnostics IID tool which allows changes to the suspension heights which can be saved as presets. Hooked up the caravan with the same 120kg noseweight and then using my phone, connected to the IID tool via Bluetooth, adjusted the rear height of the car so that the caravan was level. Now the wheels on the caravan looked to have equal tyre and suspension deflection. Driving the combination was so much better, a lot less pitching and it felt much more stable.
Now every time I tow, it’s just a case of plugging the tool into the car and selecting the preset I saved on my phone. All that changes effectively, is the towball height to give a level riding caravan.
I have no idea why this set up tows so much better, I can’t for one moment explain the physics behind it. The noseweight hasn’t changed, just by raising the rear of the car lifts the towball height to achieve a level caravan, and bingo, the towing experience is drastically improved.
Can anyone explain?
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Here is something to think about with towballs being to high that many of you will not be aware of the caravan technical department was not much use when I contacted them about it
if you fit a drop plate to a tow ball to reduce the height they have to be tested at the same time together at the point of manufacture otherwise they can void the insurance if the worst happens , also brink don't make drop plates so are never tested together and witter does not recommend them and if you tow with a commercial vehicle including pick ups they are illegal after 2014 by a Euro directive
i ordered a new 67 plate ford ranger wildtrak pickup , ford was also not aware of this issue and fair play to ford they give me my deposit back
they are a lot of people towing like this unaware of the consequences , if the worst ever happens they are giving the insurance companies a get out of jail clause
its well worth doing the research before buying a new tow vehicle, I'm glad I did
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For a twin axle trailer to balance exactly could be nice, but mine can have anything from 140kg nose weight (Reich gauge) to a negative number that I can't measure as the jockey wheel is way up in the air off the ground and I'm rushing to jump on it before the rear end makes contact with Mother Earth! This is just when motor moving, so goodness knows what the loadings are on the highway.
It does however tow very comfortably behing the Land Rover.
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Whilst looking for something else, I have spotted in the Lunar handbook that the ball hitch height for a fully laden Lunar Delta is 440mm.
This is at odds with the 350mm to 420mm range that is often stated.
My Witter towbar has two positions for the towball and I have it attached to the lower setting. However the van has a nose-down attitude when attached, so I'm off out with a tape measure tomorrow. My nose weight is generally 80-90kg.
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If the difference is anything like I’ve experienced, raising the tow ball height to lift the nose of your twin axle so that it tows level, makes a big difference. With your multi height towbar, you at least have the chance to try it, has to be worth a go.
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thats true. my delta handbook states the same 440mm/1' 5". I think the best way to get van level would be set it up on level hard ground loaded as it would be towed and then measure the hitch and stick to that measurement. hopefully your tow ball will be either at correct height or just under. but that would be to easy and perfect world. plus you would have to load the car the same every time to keep the suspension and the tow ball the same height. how many caravaners weight the nose for the homeward journey. less gas/food/liquids including wine and beer. makes you think!!!!!!
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Old post but thought I'd jump in and see it can be resurrected.
My understanding (especially for twin axles):
Nose weight must be measured at the hight the tow hitch will be when hitched up and this won't necessarily mean the caravan is level.
The caravan should be on hard level ground.
The wheels should be chocked.
What I'm not sure about is should the handbrake be ON or OFF - I believe the way the caravan moves on the suspension and hence the nose weight can vary depending if the handbrake is on or off.
All opinion/comment welcome.
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