Twin axle noseweight

[Parksy]

As I had recently purchased one of those red nose weight gauges I decided to use the bathroom scale method to determine the inaccuracy amount and then when weighing in the future take the adjustment into account. I was a bit taken back when the nose weight was about 140kgs. We moved some stuff around and got it down to about 120kg. I surmised that once we had everything like bedding back in the caravan there would be extra weight at the rear as it is an island bed and the noseweight would change.
Just to be on the really safe side, I decided that we would think about purchasing one of these. However on reflection once we got home and thought about it, when we did the weighing we did not ensure that the caravan was level. As it is a twin axle, if you lift the front and then lower it onto your stick of wood which is on the bathroom scale, it it is not level you will have a false reading as the front wheel of the two wheels on the cartavan is slightly lifted.
Am I correct in thinking that on a twin axle, the caravan needs to be level and at that point, the noseweight readng is taken. In effect as you have to lift the caravan on top of the Reich load control, this means that weight is taken off the front one of the twin wheels and transferred to the nose as the tow ball hitch is now more than 17" from the ground. The Reich load control probably will not give you a very accurate reading. Perhaps it is better to place the scale and piece of wood under the towbar hitch area to see the downward weight at that point rather than the caravan it self.
Seems that on twin axles, noseweight is not really a big issue as long as you are not stupid. I would rather have a slightly heavier noseweight that a weight in the rear causing it to wag. I think we have scrapped the Reich load control idea.

 

[Lutz]

Whether single or twin axle, the noseweight should always be measured with the hitch at the same height as when the caravan is attached to the car. If the caravan happens to be level in this condition, then this is pure coincidence, but it may not necessarily be the case.

 

[Surfer]

Whether single or twin axle, the noseweight should always be measured with the hitch at the same height as when the caravan is attached to the car. If the caravan happens to be level in this condition, then this is pure coincidence, but it may not necessarily be the case.

If the caravan is level then noseweight would be zero as there is no downward force however as the towbal may be higher than the towhitch when caravan is level then there would be a downward pressure when connected up. Coupling height is 17" but not sure if this is the height of towball on car or tow hitch on caravan.
I guess the question is how would VOSA check the noseweight on a twin axle caravan?

 

[Lutz]

If the caravan is level then noseweight would be zero as there is no downward force .........

Eh? Why would the noseweight be zero if the caravan is level? It won't be, neither for a single nor a twin axle caravan.

Coupling height is 17" but not sure if this is the height of towball on car or tow hitch on caravan.

The height of the centre of the towball should be between 350 and 420mm (13.8" and 16.5") when the caravan is hitched up.

I guess the question is how would VOSA check the noseweight on a twin axle caravan?

The same as they would measure the noseweight of a single axle caravan.

 

[forestgump]

as lutz said the hight is tobe right not only will it give a fauls reading your front /rear tyers may be taking to much load front down may mean front axle may be loaded and rear may have almost none.

 

[GrahamDerby]

Camping& Caravan mag just out Jan 2012 page 58 compares 6 nose weight measures.

 

[ProfJohnL]

Hello Surfer

The subject of how to measure noseweight has been debated hard and long on this and other forums. From the many replies on the threads it is clear most people either don't bother checking and those that do often don't understand the mechanics of how the noseweight of a given caravan changes depending on the height of the hitch above the horizontal - yet there are specific regulation concerning nose weight, and ignorance is not a legal defence.

The science and mathematics of a single axle caravan are relatively easy but to summarise :-
For a single axle caravan, the lower the hitch is the greater the noseweight will be, conversely the higher the hitch is raised the nose weight will reduce, a single axle caravan has a fairly progressive rate of change of nose weight with hitch height.

But the twin axle arrangements are substantially more complex and may not follow the same simple pattern of weight transference. In fact you can expect several Kg nose weight change with only a small change in nose height, which it is why it is particularly critical to make the nose weight measurement at the working height.

In your own postings on this thread you have made a common mistake - assuming that nose weight must be measured with the caravan level, and Lutz has already pointed that out.

The device you point to is inherently flawed as it raises the hitch above its working height, so it will not give an accurate measurement of noseweight, and for twin axle may be substantially out.

 

[Parksy]

How often has any forum member been stopped either by the police or VOSA for a 'noseweight check'?
What consequences befall those that don't bother to check their noseweight?
Has anybody ever had to appear in court to plead the ignorance about noseweights to which there is no defence?
How accurate are commercially available noseweight gauges and who decides what is accurate and what is not?
Has a court ever ordered a noseweight gauge to be tested for accuracy as a result of a prosecution?

Obviously you wouldn't want to overload your caravan or any component of it but as soon as your towing vehicle hits a pothole ( of which there are plenty) the noseweight at the hitch will change dramatically and every single movement of the tow vehicle suspension will cause the measurable noseweight at the tow hitch to alter to some degree.
How then could VOSA launch a successful prosecution when the basis for prosecution is subject to so many variables which would be next to impossible to prove one way or the other?

The best that you can hope for would be to achieve a noseweight broadly within the legal parameters for the height at which your caravan is hitched to your towing vehicle.
Start by not overloading your caravan.
Those attempting to get their noseweight absolutely correct to within a couple of Kg by shifting equipment around the caravan are probably carrying too much equipment inside their caravan in the first place.
Heavy items at the back of a caravan may well correct noseweight discrepancies but could introduce an unacceptable degree of instability because of the tail wagging the dog scenario.

 

[TD42]

the Need to arive at the correct noseweight for your car is not JUST a legal requirement It is also a car /towbar related safety requirement.A vehicle manufactorer gives a stated max noseweight fully aware of the possible variations of nose load due to the dynamics of towing THIS IS WHY THEY STATE THE MAX LOAD. its in order to keep it within the maximum safe load conditions in the worst scenario.loading a 75kg allowance to 100kg would in all possibility exceed the MAXIMUM possible load of the tow bar fixings or the maximum possible load on the rear axle/suspension.
For the OP the noseweight whether on a twin axle or a single axle caravan must be calculated at the height the caravan hitch will be when hitched to the tow car.Ie. measure the height of the top of the loaded car tow ball,& 0n level ground load the caravan to achieve the required noseweight with the hitch at the height of the loaded cars tow ball.
personally I have cut a length of broomstick to fit inside the van tow hitch making sure the total height of the scales,& broom stick equal the height of the TOP of the car tow ball. I have also made a block up so that my noseweight guage when compressed to the required load is also at the correct height of the tow ball.I have also checked the accuracy of the guage against the CHECKED accuracy of the scales & found it to be 10kg out

 

[Lutz]

Quite frankly, as Parksy has pointed out, it is fairly unlikely the VOSA will ever get too interested in measuring noseweights. I'm sure that such measurements don't figure very highly in their list of priorities. However, should an accident happen due to the outfit becoming unstable on account of inadequate noseweight, the insurance companies could very well refuse to settle a claim. Conversely, if material failure should occur if the noseweight is too high, one would not have any right to recourse action against either the car or the towbar manufacturer. For this reason, one should attempt to set the noseweight correctly, even if it's hardly likely that one may fall foul of VOSA.

 

[Parksy]

I pointed out that overloading should be avoided in my earlier posts but the reason for my comment is that over the past 12 years or so I can count on one hand the number of times that I've seen anyone check the noseweight before leaving a site.
I'd agree that if there was a component failure which could be proven to have been caused by too high a noseweight there would be difficulties with insurance companies but if there was an error in noseweight checking (say, because the gauge was inaccurate) I'd rather err on the side of slightly too much than too little which is known to cause instability.
I'm by no means advocating exceeding manufacturers limits but imho it's doubtful whether anyone could ascertain their noseweight with 100% accuracy every time. If the noseweight is set by moving items around inside the caravan what's to stop something like an awning shifting back or forth on the caravan floor during a journey? Even a slight shift would alter the noseweight which is why I think that although overloading and exceeding manufacturers limits should be discouraged there's not much point in worrying about a couple of kilos.

 

[Surfer]

Once you have loaded a caravan and checked the noseweight, then there is no necessity to do it every time you go out providing you store the goods inside the caravan the same way as when you did the main check.
As per John's post. Why do you think the Reich load control for twin axles will be inaccurate? Also on just about every forum plus others it states that a twin axle caravan should be level when doing a noseweight check and that the noseweight is then determined by the downward force on the towball when it is hitched.
I have just measured the distance from the ground to the middle of the towball and it is 19" unladen. According to Lunar the coupling height should be 17". The hitch on the towing vehicle is on the lower bolts and cannot be placed lower at this time, however when laden will definitely drop down to under 420mm. I am guessing that perhaps the stick needs to be cut to 19" and then with the bathroom scales determine the downward pressure or noseweight on the towball.

 

[colin-yorkshire1]

hi all,
please excuse my ignorance as I have never had a t/axel van but have occasionally towed t/axel plant transporter type trailers,
if the trailer IS stood on level ground then the fact that the axels support the weight in a counterbalance stort of way to a point where the jockey wheel is not required, there will be a height where as surfer said the nose weight is zero if by some quirk the ball height is exactly this same measurment then surely the noseweight on the car would be zero, a ball height that is higher would give a positive reading as the the front axel would have to be lifted transfering the fulcrum point further back towards the rear axel and conversly if the ballheight is lower then the nose weight would be negative as the fulcrum point is moved forwards.
this being the case surely on a t/axel the ball height is more important than guesswork with a gauge as if the ball height is measured and a reading taken when the towcar is loaded/unloaded the nose weight will have changed.
I would have thought the best starting point was to determine the working height of the ball and or hitch in relationship to the counter balance point BEFORE tinkering with weight distibution to adjust the overall noseweight.
colin

 

[ProfJohnL]

Hello Surfer

Your last reply covers several points that interact with each other.

I have rearranged their order so my answer can follow a more logical path.

you wrote:-
"According to Lunar the coupling height should be 17".

This single statement actually has several elements to it:-
Why Lunar would be quoting an imperial measure, I don't know unless you have a pre-MKS built caravan.
All caravan manufactures are aware of the current EU regulations that dictate that the fully loaded towball of a car should settle between 350 (13.7") and 420mm (16.5") vertically above horizontal ground to the centre of tow ball.
However to set the caravan level (which is not necessarily the towing height) the caravans hitch height may need to be 17"(432mm)

"The hitch on the towing vehicle is on the lower bolts and cannot be placed lower at this time, however when laden will definitely drop down to under 420mm."

Some 4x4 and commercial vehicles are exempt from the above 350 to 420mm regulation, you will need to check with your vehicle supplier to establish if the regulation applies to your vehicle or not.

"I have just measured the distance from the ground to the middle of the towball and it is 19" unladen."

The unladen height of the hitch has no relevance it is only the ride height of the hitch when the car is laden including the caravans nose weight when it is connected to the car.

"I am guessing that perhaps the stick needs to be cut to 19" and then with the bathroom scales determine the downward pressure or noseweight on the towball."

If you are using a stick, it needs to be cut to match the ride height of the caravan hitch and you obviously need to compensate for the thickness scales as well.

"Also on just about every forum plus others it states that a twin axle caravan should be level when doing a noseweight check and that the noseweight is then determined by the downward force on the towball when it is hitched".

The two conditions in the above statement are very unlikely to occur together. Consider how many caravans are actually level when hitched to their tow vehicle? Very few, and those that are it is a pure coincidence. I wonder if you have missed a word out, because the nose weight measurement of any outfit must be carried out on level ground, this does not mean the caravan floor is level.

Specifically for the noseweight measurement, The regulations refer to the "static vertical nose load" on the towing vehicles hitch. Due to the physics of the car and caravans geometry and its interaction with the caravan centre of gravity the noseweight actually changes depending on the height of the hitch above the horizontal consequently the true nose weight will only be produced when the caravan hitch is at the same height as when it is settled on the car ball. Any other hitch height will produce a different noseweight measurement.

"Why do you think the Reich load control for twin axles will be inaccurate?"

The Reich device attaches to the car tow ball. and then the caravan is attached to the top of the device. I estimate from the picture I have seen that the caravans hitch will be 75 to 80mm higher than the cars ball, thus for the reasons given above, the device will not experience the actual noseweight of the caravan. For a single axle caravan, the device will give a lower reading than the actual noseweight. It is not so simple to predict the variation for a twin axle, but with a TA just a few mm differences can result in big differences in the noseweight. Colin is absolutely correct when he writes that great care is needed with TA's to get the noseweight right.

With regards Parksys. posting Just because most people do not check their nose weights does not make it alight to miss it out.
And as per my posting in a separate technical thread, the noseweight limit is an absolute limit and should not be exceeded.

 

[Steve L]

I have towed both single and twin axle caravans.
You should check nose weight with the caravan and car on level ground.
The hitch needs to be at about the level of the tow ball on the car. I use a guage that fits between the hitch and ball to check my van after having set it up using the bathroom scales method with the hitch level to the car's ball.
I check the nose weight before starting a journey every time, despite me having a specific loading plan for all the goods in the van.

VOSA can only go on the look of the outfit when your on the road and they formulate an oppinion from that! Then it's down to you to proove them wrong

if you dare.

I recently collected a 18ft twin keel sailing yacht from falmouth and towed it 250 miles back home under cover of darkness

.

My reason for that was that I had extended the drawbar of the trailer by 5ft to get the length suitable for the boat. Thus giving the impression that the boat only weighing 800Kgs was on a 6 x 4ft box trailer with an extra long tow bar. So to the ill informed, it looked rediculas!

Actually it was legal, because the trailer is rated at 1 ton gross weight, it has a weight plate to that effect, it has over run brakes, and the tyres were correctly inflated to 44psi which is the max casing pressure for the tyres fitted.

I chose to drive at night simply because of the look of the load and the knowledge of past encounters with inter plod and VOSA and their crystal ball, x ray vision and the good old "pet hate" syndrome.

So long as your trailer is loaded correctly and the load strapped down, tyres correctly inflated, there should be no reason to be spot checked.

 

[ProfJohnL]

I must comment on Steve's posting

He starts by saying "The hitch needs to be at about the level of the tow ball on the car."

For compliance, the caravan hitch must be at the same height as when it is coupled to the tow vehicle, not the unloaded ball height.

he tells us that he uses noseweight gauge similar (or the same?) as the Riech.

For the reasons I have given above, such a device does not give the correct nose weight.

He goes on to say he calibrates it against a stick and scales, which provided the trailer is a single axle and loaded in the same way will work and . But the way a TA changes its nose weight against height is different to that of a single axle, and thus his method will be unreliable for TA's

I cannot predict the variation for the readings using Steve's method, but especially for TA it may be quite large. Why risk it? do it right and avoid conflict.

 

[Surfer]

I must comment on Steve's posting

He starts by saying "The hitch needs to be at about the level of the tow ball on the car."

For compliance, the caravan hitch must be at the same height as when it is coupled to the tow vehicle, not the unloaded ball height.

he tells us that he uses noseweight gauge similar (or the same?) as the Riech.

For the reasons I have given above, such a device does not give the correct nose weight.

He goes on to say he calibrates it against a stick and scales, which provided the trailer is a single axle and loaded in the same way will work and . But the way a TA changes its nose weight against height is different to that of a single axle, and thus his method will be unreliable for TA's

I cannot predict the variation for the readings using Steve's method, but especially for TA it may be quite large. Why risk it? do it right and avoid conflict.

With the Reich load control for twin axles, you ensure that the caravan is level then can place the load control on the on the towbar or if this is not possible the towball as it may then compensates for the extra height or so I am told.
I am not sure how John can comment if he has not used one or even seen one unless I am wrong and he has one in his possession and has used it.
Hopefully tomorrow I will be viewing one in the flesh so to speak and can then give a more honest appraisal of the device after a demonstration.

 

[ProfJohnL]

Hello Surfer,

I can comment based on working for many years with many different trailers both single and twin axle, and having noted the effect that has been described and taken the time and trouble to understand it and its implications. It is particularly important when nose weights are set very close to the car or caravans upper limits, which is where many caravanners aim to be.

Specifically the way the Reich unit works is fully demonstrated in the suppliers pictures, and it clearly raises the caravans hitch and that will give inaccurate readings for all trailers but especially so for TA trailers.

A company I worked for was involved with a series of designs of caravan movers. They had test bed chassis that could be loaded in a variety of ways to check the capability of prototype movers.

As most of us know if you want to turn a TA by hand you usually need to raise the hitch by extending the jockey wheel to reduce the load on the forward axle, and this eases the job of turning the unit, though it can still be very hard. The company needed to put some figures to the loads involved and so measured the jockey wheel load through a range of height adjustments.

The results predictably showed some marked difference between single axle and TA chassis. With a single axle the hitch will dip to the floor and at that point it will exert more weight that when it is raised higher. The rate of change is relatively smooth.

However the results for the TA are markedly different. Because of the twin axle, it is frequently the case that you can retract the jockey wheel completely, and the hitch will 'float' rather than fall to the ground. Where it 'floats' means there is no nose weight, however, try to lift it or push it down and it resists strongly. In many such instances a 25Kg force will only raise or lower the hitch by 75mm or so. The exact force/distance will be different for each caravan and depends on how it is loaded.

Consequently any measurement device that changes the height of the hitch will give false noseweight readings.

 

[Martin_E]

There are two versions of the Reich load control, it looks like the TLC is for single axle vans and then there is another version for twin axle vans. "This version is for single-axle caravans or trailers; there is also a twin axle version which automatically takes into account the different load distribution involved" MORE INFO

 

[Lutz]

When looking at the Reich website, I see no reference to two versions. Their website only quotes one part number (522-5000).
In any case, I don't why there should be a different version for twin axle trailers and single axled ones. After all, the towbar on the towcar can't distinguish between the two, either, and it's the load on the towbar that it's all about.

 

[Surfer]

There are two versions of the Reich load control, it looks like the TLC is for single axle vans and then there is another version for twin axle vans. "This version is for single-axle caravans or trailers; there is also a twin axle version which automatically takes into account the different load distribution involved" MORE INFO

Thank you Martin. It does state that it compensates for twin axles and according to the latest C & CC magazine it is fairly accurate although readings indicated 3kg and 6kg over actual loading on 50kg and 100kg respectively. The only one that was really precise was the Milenco Precision Calibrated which was only about 1kg out.
Obviously John cannot get his head around the compensating bit. Perhaps his Xmas was too merry. LOL

 

[RogerL]

How does the Reich TLC compensate for raising the hitch height by 3-4 inches, which it clearly does when inserted between the car and caravan - that alteration in angle could make a huge difference in some cases.

 

[otherclive]

I am one of those 'sad' people who tend to use the noseweight gauge most trips including the return home too even though we (should) have standard packing lists and stowage places; but OH does tend to ferret stuff away when I am not looking! I use the Milenco calibrated gauge which has about 30cm between 75kg and 100kg, so given the sensitivity of TA vans to noseweight and hitch height it would seem to be important even using such a gauge to ensure it is used at the corrrect height for the car when loaded. So it may need to be placed on a piece of wood or I use a plastic chopping board. The test in C&CC magazine made no mention of any need for height adjustment or alignment sensitivity. I feel the need for another ALKO electronic device (load cell) within the stabiliser-hitch head coming on!!

 

[Lutz]

It does state that it compensates for twin axles and according to the latest C & CC magazine it is fairly accurate although readings indicated 3kg and 6kg over actual loading on 50kg and 100kg respectively.

The towbar on the car doesn't recognise whether a twin or a single axle has been hitched up, so what is there to compensate?

 

[Surfer]

I went and viewed the Reich Towball Load Control device and it seems okay. It fits over the towball itself almost as if it si the hitch on the caravan. The hitch on the caravan is then lowered onto it. There is a slight difference in height of maximum 2 inches with teh hitch being 2 inches higher. The TLC then compensates for this difference as nose weight will be slightly higher due to the raise hitch.
Quite impressed with it and it is easy for me to read the guage without having to go do on my hands and knees. We have bought one and hopefully will be trying it out within the next few weeks.