Twin axle noseweight

[ProfJohnL]

Hello Surfer,

I hope you had a good Christmas. Mine was fine and as I was driving I avoided alcohol, so my mind is as sharp as ever.

I don't like trivialising subjects like this as they are a matter of law and we should all try to comply.

Let me be clear, in your opening posting you provided a link to
http://www.amazon.co.uk/Reich-Towbar-Load-Control/dp/B003DOCHYC

This is the Towbar Load Control, by Reich part number 127499.

The description makes no differentiation between it suitability for SA or TA trailers, thus as you pointed to it, it was reasonable to assume your posting was about this specific model.

I was not aware that Reich offered a model designed with TA's in mind, and as yet I have been unable to find any technical information about it, I cannot comment about how or if it can adequately compensate for the noseweight/height issues. though I am very sceptical about how the device can automatically compensate for factors such as suspension compliance, vertical height of CoG level lengths of hitch to both axles, etc. What is clear is that Reich do recognise that TA's represent a more difficult set of criteria to SA as far as noseweight is concerned.

It is interesting to note the comments regarding the C&CC nose gauge comparison tests. Whilst I have not seen the actual report, to read of 6 to 10Kg errors is not surprising, considering the additional height the device gives.

The other fallacy that often arises regarding gauges and meters is that Digital devices will often assumed to be "more accurate" This is far from the truth, and just because something is digital does not necessarily make it better or more accurate. I could go into a lot of detail about analogue vs digital measurement, but that is a whole topic on its own.

The fundamental fact remains that the legal noseweight measurement is to be carried out with the trailer hitch at the same height as its actual towing height - not with the trailer simply level.

 

[Lutz]

The TLC then compensates for this difference as nose weight will be slightly higher due to the raise hitch.

Surfer, by raisng the hitch, the noseweight will normally be lower, not higher. This is definitely the case for a single axle and probably for most twin axles, too, unless their suspension rates of both axles are abnormally high, i.e. on the verge of being solid axles.

This is the Towbar Load Control, by Reich part number 127499.

The number that you quote, John, is probably the CaravanStuff4U order number, not the Reich part number because the Reich website quotes 522-5000.

 

[Sproket]

Reich

522-5000 Reich TLC Digitale disselweger voor enkelassers € 39,95
522-5200 Reich TLC Digitale disselweger voor tandemassers € 39,95

http://www.ivra.nl/documents/prijslijsten/control.pdf

I have the 522-5000 Single Axle one, & i bought it when they first came out.
I do remember there being another part No & i think it is the one above.
Here is mine coupled into the coupling & sat onto a shocklink ( another E-Bay bargain )

The easiest way is to clamp it in a upright position with the clamping action of the stabiliser pads
Then lower it onto the ball & just wind the jocky wheel clear of the ground.....

 

[Martin_E]

I emailed someone I know at Reich about the height difference,
all that came back was "There is a calculation made for the height of the TLC ball over the car tow ball" I am not sure if the maths are done by the load cell or if there is a calculation in the box, I have asked the question and will post once I know.

 

[Martin_E]

OK have heard back.......

"The calculation is carried out automatically within the TLC"

So I guess that answers some of the speculation now

 

[RogerL]

I'm still sceptical.
The height of the caravan hitch when level will depend on a number of things - primarily on the radius of the tyres and the exact loading on the chassis suspension rubbers - different caravan MTPLM but built on the same AlKo chassis will have marginally different level heights. The angle of tilt down to the actual hitch will therefore vary and because of the CoG's height have a variable effect on the noseweight
Since I don't see how the Reich TLC can make an accurate adjustment without knowing that information I'd have to assume that it's just a "standard" adjustment - but that's little different to weighing the jockey wheel on bathroom scales and then making an approximate adjustment for the fact that the jockey wheel is in a slightly different position to the hitch.
It's a pity Reich haven't answered with any real information.

 

[Martin_E]

Roger,

I dont think you would ever get an exact nose weight measurement no matter what you do, every car will sit slightly differently to another every van will as well, I think the point of the gauges are to give you as near as practicable measurement that is meaningfull so you dont exceed the limits if someone is running that close to the limits then I think there could be cause for concern to start with,

 

[Dustydog]

I'm still sceptical.
The height of the caravan hitch when level will depend on a number of things - primarily on the radius of the tyres and the exact loading on the chassis suspension rubbers - different caravan MTPLM but built on the same AlKo chassis will have marginally different level heights. The angle of tilt down to the actual hitch will therefore vary and because of the CoG's height have a variable effect on the noseweight
Since I don't see how the Reich TLC can make an accurate adjustment without knowing that information I'd have to assume that it's just a "standard" adjustment - but that's little different to weighing the jockey wheel on bathroom scales and then making an approximate adjustment for the fact that the jockey wheel is in a slightly different position to the hitch.
It's a pity Reich haven't answered with any real information.

I think you're right Roger.
We all get too carried away with what is a very simple thing..
Our Learned Prof has already spelt out in simple terms what it's all about. Why do people like Reich try and reinvent the wheel, well they try but make it complicated.
I've had both SA & TA. The fact is they both need the noseweight carefully measured per Prof John's guidelines. There is no difference at all betwen the two.

For me as stated by others measure the noseweight at the exact height the draw bar will be when attached to the vehicle "after " the car suspension has setteled. In my case it varies beacause I have self levelling suspension so I know at the outset the exact hitch height. The rest is simple. A TA needs a noseweight on the tow ball exactly as does a SA..

 

[Lutz]

OK have heard back

"The calculation is carried out automatically within the TLC"

So I guess that answers some of the speculation now

What calculation?

Note to RogerL:
The height of the CoG only indirectly influences the noseweight. More important, it's how far ahead of the axle it is (horizontally). However, the higher the CoG, the bigger the change in noseweight due to a change in the tilt angle.

 

[ProfJohnL]

The crux of the matter is that you should not exceed the noseweight limit of either the car or the trailer, so how do you ensure that is the case. The only safe and sensible solution is to set the noseweight by measuring it properly.

The only safe and meaningful method is to check the noseweight at the hitches ride height.

Martin E is perfectly correct when he says "I dont think you would ever get an exact nose weight measurement" The C&CC report apparently shows that no gauge is 100% accurate, and many are in fact substantially out, and that doe not even take into account the errors introduced by inaccurate measurement methods such as the wrong height etc.

Even the Milennco which is claimed to be calibrated, may indeed be accurate at reporting the applied load, but if its load compressed length does not match the ride height its results will be wrong.

I have yet to see a retail noseweight gauge that provides the essential height adjustment to enable the true noseweight to be delivered to the gauge.

As this is an important issue, and it only comes about when towing a trailer perhaps the trailer manufacturers should look at incorporating a noseweight gauge into the coupling, so it is always there and can be checked by the driver or the authorities whilst it is still hitched to the car.

 

[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.

Points that I raised last Friday but hey ho

There would appear to be no 100% accurate method of achieving the absolutely correct noseweight using the equipment currently available to those of us who tow touring caravans.
I know of at least one instance in which insurers mentioned to a driver towing a caravan which was a total loss that too little noseweight may have contributed in some measure to the cause of the incident, the caravan had only been bought that weekend, it was empty and the tow car driver was inexperienced.
In spite of the oft repeated forum mantra that a limit is absolute and must never be exceeded I do my best using the equipment that I've got to achieve a correct figure but I would never lose any sleep if I was slightly over because of the previously stated inaccuracies.
If I was involved in an 'incident' resulting in an insurance claim how would the insurers work out if I'd been slightly over to use this as a basis for refusing a claim?
I'd worry about having insufficient noseweight though

 

[xtrailman]

I did some tests on my last caravan unladen.
Level it was 50kg.
But 1" above level or below, the difference didn't exceed 4kg.
I will do the same with my Valencia, next Feb' when i put the wheels back on.
It only takes 10 mins, do your own test.

 

[RogerL]

I know of at least one instance in which insurers mentioned to a driver towing a caravan which was a total loss that too little noseweight may have contributed in some measure to the cause of the incident, the caravan had only been bought that weekend, it was empty and the tow car driver was inexperienced.

I've long held that noseweight should be as heavy as possible, but not exceeding any of the limits of car or caravan.
My one and only major snake was down to a very low noseweight because in my early caravanning days I rarely ever checked the noseweight - since then I check it regularly.
Anyone who uses international forums for their car will know that there's a big difference in attitude an vehicle limits despite there being no engineering reason for the differences on otherwise identical vehicles often built in the same factory:-
Australia uses similar towing limits to us, ie often exceeding the kerbweight, but has much higher noseweight limits to allow the widespread use of load-equalising hitches - they regard 10% of kerbweight as a good noseweight.
North America uses much lower towing limits than us, around half but this is mainly due to their very long grades up into the mountains which go on for 10's of miles - their noseweight limits are similar to ours but still look for around 8-10% of kerbweight.
Europe uses high towing limits but perversely low noseweight limits, often 4-5% of kerbweight.

I routinely check the noseweight using the jockey wheel on the bathroom scales and make the slight adjustment necessary to correct the lever distances involved - I also use a simple noseweight gauge for which I know the expected reading compared to the scales - this works well on site but is of limited use on any site which isn't level - ie MOST of them !!!!

 

[Surfer]

As I said previously when a twin axle is level nose weight should be zero as there is no downward force. My towball sits at 19" from ground level. The twin axle when level, the coupling hitch sits at about 17" which is the coupling height as per Lunar. IMHO the fact is that the caravan hitch will be pushing down on the towball as the coupling is two inches lower. This downward pressure of the caravan pushing down on the towball will be noseweight.
If you now insert the Reich twin axle Load Control in between there is now a difference of an extra two inches and the nose weight should increase as the front wheels of the twin axle are lifted marginally creating more downward pressure on the towball. The TLC probably uses an average to compensate as the maximum static load at the coupling head should be 100kg for all ALKO products.
IMHO 3 - 6kg over read is hardly an issue especially if you do not have to get down on your hands and knees to read the scale.

 

[colin-yorkshire1]

hi all,
I agree with Parksy, because of all the variable factors involved I would not lose any sleep over it either.
my last car had a max nose weight of 75kg using the standard criteria aimed at figure of 60 to 65kg wich seemed about perfect the van towed well with minimum pitching and also looked level when hitched up to the car.
the new one (meriva) has a max nose weight of 50kg so I will have to do some load adjustments and a front locker clearout me thinks??
I only mention this because the hand book clearly states "the maximum ball load should not exeed 50kg, however it should be loaded as close to this figure as possible for best results" given all the inaccurate critria mentiond previously this could be a intresting project when the van comes out of hibernation in march

 

[RogerL]

As I said previously when a twin axle is level nose weight should be zero as there is no downward force.

That will only be true if the CoG is exactly between the two axles - unlikely.

 

[RogerL]

My towball sits at 19" from ground level.

As off-road 4x4s have the Type-Approval height requirement removed that 19" isn't wrong as such - but you might well get a better tow if you use a drop plate to get it within the 350-420mm (14-16") required for all other vehicles.

 

[Surfer]

My towball sits at 19" from ground level.

As off-road 4x4s have the Type-Approval height requirement removed that 19" isn't wrong as such - but you might well get a better tow if you use a drop plate to get it within the 350-420mm (14-16") required for all other vehicles.

When the caravan is coupled up to the vehicle, the noseweight of the caravan pushes down on the towball taking it to between 14 - 16 " which should then give it a good tow.
Prior to leaving the site after our last road trip we removed all the linen including the duvert and pillows from the rear island bed and this had a detrimental effect on the nose weight increasing it by about 30kgs even though the linen removed was only about 10 kgs!
Main reason why we decided to purchase a more reliable easy to read nose weight guage as the ride back was not very comfortable due to light steering. Luckily it was less then 10 miles back to storage on an A road. Lesson learnt!

 

[Dustydog]

As I said previously when a twin axle is level nose weight should be zero as there is no downward force.

My Bailey TA has always had a propensity to a "heavy" noseweight even when totally empty , straight from the factory.
As far as I know this is a deliberate act on the part of Bailey , and I suspect other manufacturers, to ensure some margin of safety when towing empty.

 

[ProfJohnL]

Oh Surfer,

Please please please understand that if you raise the jockey wheel of a TA off the ground so the caravan is sitting just on its main wheels, the nose may settle and float at at some height above the ground. If the nose weight is big the hitch may settle on the floor or if it is small the hitch will rise. It will be purely coincidence if the caravan settles level In 99.999% case it will not be level

So a level TA does not automatically give zero nose weight. This is so crucial in the case of a TA, as only slight differences in the height of the hitch can produce substantial nose weight changes.

Do it right to get it right.

Again I have to contradict Parksy, you should not exceed noseweight limits. It is not a responsible or safe argument to suggest that because no one has reported being stopped or prosecuted for excessive nose weight that it is satisfactory practice.

 

[Lutz]

I've long held that noseweight should be as heavy as possible, but not exceeding any of the limits of car or caravan.
My one and only major snake was down to a very low noseweight because in my early caravanning days I rarely ever checked the noseweight - since then I check it regularly.
Anyone who uses international forums for their car will know that there's a big difference in attitude an vehicle limits despite there being no engineering reason for the differences on otherwise identical vehicles often built in the same factory:-
Australia uses similar towing limits to us, ie often exceeding the kerbweight, but has much higher noseweight limits to allow the widespread use of load-equalising hitches - they regard 10% of kerbweight as a good noseweight.
North America uses much lower towing limits than us, around half but this is mainly due to their very long grades up into the mountains which go on for 10's of miles - their noseweight limits are similar to ours but still look for around 8-10% of kerbweight.
Europe uses high towing limits but perversely low noseweight limits, often 4-5% of kerbweight.

I routinely check the noseweight using the jockey wheel on the bathroom scales and make the slight adjustment necessary to correct the lever distances involved - I also use a simple noseweight gauge for which I know the expected reading compared to the scales - this works well on site but is of limited use on any site which isn't level - ie MOST of them !!!!

You are correct in your statement that a higher noseweight is normally beneficial to stability and that's why the Australians recommend 8-10%. This is no great problem so long as you are towing with pick-ups or larger 4x4's, but the average saloon car or estate, which are the mainstay of vehicles towing caravans in Europe, would be hopelessly overchallanged with such high noseweights. European manufacturers have therefore settled for a lower compromise. The legal limit of 4% minimum also reflects this philosophy.
The reason why American manufacturers specify lower towloads than the rest of the world has less to do with gradients (there are some quite long gradients in the European Alps, too), but they are less willing to compromise on acceleration when towing. Also, the Americans set lower standards for brake fade than the Europeans and this also prevents them from specifying higher towloads without jeopardising safety.

 

[Parksy]

.........Again I have to contradict Parksy, you should not exceed noseweight limits. It is not a responsible or safe argument to suggest that because no one has reported being stopped or prosecuted for excessive nose weight that it is satisfactory practice.

I'm not trying to argue that excessive noseweight is a satisfactory practice John.
I'm suggesting that it's well nigh impossible to measure noseweight with 100% accuracy.
The noseweight should be measured with the tow hitch at the height of the towball when the vehicle suspension is settled at the ride height:

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.

Surely the noseweight of the caravan will affect the height of the towball with the caravan hitched and loaded ready for a trip?
If we therefore assume that the noseweight for any given caravan is either unknown or incorrect before the measurement is taken how would the true 'ride height' be determined in order for an accurate measurement to be taken?
A noseweight below the limit should produce a higher ride height, above the limit would produce a lower ride height.
Any other hitch height will produce a different measurement but if the noseweight is unknown the correct ride height wouldn't be be determined.
Variations in tyre pressures, the amount of fuel, luggage and people carried inside the car would also produce variations in ride height but I've yet to see caravanners sawing up bits of timber to place underneath their hitch to compensate for the true ride height to measure it accurately.
It's all a bit of a compromise really.
As far as I'm concerned noseweight measurement relies on educated guesswork and can never be truly accurate which is why although I keep broadly within limits for my 4x4 (100kg Alko hitch limit) and I never overload my caravan I never worry too much about noseweight being spot on because the chances are that it won't be.

 

[RogerL]

To even start to determine the noseweight, the car and caravan have to be loaded for touring and then parked on a level surface where the resultant towball height can be measured - then the caravan has to be unhitched to measure the noseweight having adjusted the hitch height to be as measured previously!
John made a very valid point about never seeing a noseweight gauge with any adjustment facility to ensure the hitch height is at normal towing height.
I'll stick to using the jockey wheel on the bathroom scales - that way the height can be adjust to MY normal towing height.

 

[Surfer]

Oh Surfer,

Please please please understand that if you raise the jockey wheel of a TA off the ground so the caravan is sitting just on its main wheels, the nose may settle and float at at some height above the ground. If the nose weight is big the hitch may settle on the floor or if it is small the hitch will rise. It will be purely coincidence if the caravan settles level In 99.999% case it will not be level

So a level TA does not automatically give zero nose weight. This is so crucial in the case of a TA, as only slight differences in the height of the hitch can produce substantial nose weight changes.

Do it right to get it right.

Again I have to contradict Parksy, you should not exceed noseweight limits. It is not a responsible or safe argument to suggest that because no one has reported being stopped or prosecuted for excessive nose weight that it is satisfactory practice.

John I am astounded that you offer such misleading information especially when you claim to be a prof. Even an idiot knows that a level twin axle caravan will have no noseweight. Perhaps you could enlighten us with your definition of what is nose weight? I define it as "This is the amount of weight that the trailer puts in a downwards direction on the tow bar or the rear of the vehicle. ".
I really think you are in la la land with this one, but thanks for responding any way as it made me laugh on this miserable day.

 

[RogerL]

I am astounded that you offer such misleading information especially when you claim to be a prof. Even an idiot knows that a level twin axle caravan will have no noseweight.

You're on your own on this one !!