Nose gauge & weight distribution problems

[Lutz]

As long as the nose weight is reasonably accurate, there is no concern. After all when travelling the nose weight could probably fluctuate between zero and +200kg.

Instantaneous dynamic values will fluctuate a lot more than that.

 

[Buckman]

Instantaneous dynamic values will fluctuate a lot more than that.

I think we all know that which is why I used the word "probably" as none of us really knows!

 

[Lutz]

I think we all know that which is why I used the word "probably" as none of us really knows!

True, but in the engineering community one generally works with peak values approximately 8 times the nominal static figure.

 

[Buckman]

True, but in the engineering community one generally works with peak values approximately 8 times the nominal static figure.

However most people using a caravan are not engineers. After all we are only talking about nose weight on a flimsy caravan and not launching a complicated tech heavy satellite into outer space. 🤣

 

[Lutz]

However most people using a caravan are not engineers. After all we are only talking about nose weight on a flimsy caravan and not launching a complicated tech heavy satellite into outer space. 🤣

Whether it's something complex like a satellite in space or a simple caravan being towed over a potholed road, a peak being many times the static value will be about the same. An instantaneous peak noseweight value of 800kg or even more wouldn't be unreasonable to expect if the caravan hits a pothole or an unexpected speed bump. Besides, it may surprise you, but even caravans are engineered.

 

[ProfJohnL]

With the deteriorating condition of many of the UK's roads, both the frequency and severity of shock loads imposed into an outfit by towing are increasing. The shock loads are expressed as accelerations proportional to earths gravity hence we give them the initial unit of G's. And because the dynamic loads are directly proportional to the static load, multiplied by the G forces imposed by the motion of the outfit, there is an increasing chance of exceeding the designed safety margins if you exceed the manufacturers static S values. It is mechanically sensible to maximise your safety margin, by only using enough of your nose load capacity to endow your outfit with adequate stability to cover normal driving.

 

[Hutch]

With the deteriorating condition of many of the UK's roads, both the frequency and severity of shock loads imposed into an outfit by towing are increasing. The shock loads are expressed as accelerations proportional to earths gravity hence we give them the initial unit of G's. And because the dynamic loads are directly proportional to the static load, multiplied by the G forces imposed by the motion of the outfit, there is an increasing chance of exceeding the designed safety margins if you exceed the manufacturers static S values. It is mechanically sensible to maximise your safety margin, by only using enough of your nose load capacity to endow your outfit with adequate stability to cover normal driving.

Or in other words,
That was a a bloody big thump at the back.

 

[Buckman]

Even if you are 10-20kg over the nose weight limit, is it really going to make much of a difference overall to any safety margin, however it is always best to stay within the guidelines recommended by the manufacturer. With our Lunar 640 the most comfortable tow was with nose weight at 110kg exceeding the recommended 100kg by 10kg. This was about 6% of the MPTLM.

 

[Lutz]

I would question claims by anybody saying that a10kg change in noseweight, whether up or down, makes an appreciable difference to the way an outfit handles. I would put any such claims down to the total sum of all contributing factors influencing its stability.
I have to practically remove noseweight of my caravan altogether before I can say it’s difficult to handle.

 

[ProfJohnL]

Even if you are 10-20kg over the nose weight limit, is it really going to make much of a difference overall to any safety margin, however it is always best to stay within the guidelines recommended by the manufacturer. With our Lunar 640 the most comfortable tow was with nose weight at 110kg exceeding the recommended 100kg by 10kg. This was about 6% of the MPTLM.

If you exceed any specified threshold level, you erode the built in safety margin.

If the S value is 100kg, and if you have exceeded a 100kg limit by 20kg that is a 20% overload. to put that into perspective based on Lutz 8x suggested dynamic load capability, if the S value is given as 100kg, 8x would mean the towbar/aframe is designed to withstand dynamic loads of 800kg. if you exceed the S value with a 120kg load the peak 8x dynamic load could rise to 960kg ! That is a very significant overload.

The manufacturers establish their load limits based on technical procedures and testing for good reasons, . It is unwise to exceed those limits, and it's certainly irresponsible to suggest to others it's a satisfactory practice without risk.

Whilst excess nose load may not break an specific law or regulation, if damage does arise that might be attributable to excess nose load you will probably lose any manufacturer's warranty cover and it could be a negative factor in a CRA case. Arguably exceeding a stated specification could be interpreted as operating a vehicle unsafely, which might produce a prosecution, and might invalidate your insurance.

 

[Buckman]

If you exceed any specified threshold level, you erode the built in safety margin.

If the S value is 100kg, and if you have exceeded a 100kg limit by 20kg that is a 20% overload. to put that into perspective based on Lutz 8x suggested dynamic load capability, if the S value is given as 100kg, 8x would mean the towbar/aframe is designed to withstand dynamic loads of 800kg. if you exceed the S value with a 120kg load the peak 8x dynamic load could rise to 960kg ! That is a very significant overload.

The manufacturers establish their load limits based on technical procedures and testing for good reasons, . It is unwise to exceed those limits, and it's certainly irresponsible to suggest to others it's a satisfactory practice without risk.

Whilst excess nose load may not break an specific law or regulation, if damage does arise that might be attributable to excess nose load you will probably lose any manufacturer's warranty cover and it could be a negative factor in a CRA case. Arguably exceeding a stated specification could be interpreted as operating a vehicle unsafely, which might produce a prosecution, and might invalidate your insurance.

I am sorry, but you are going totally over board and your comments on the nose weight are probably not very valid. How will the manufacturer prove that you have exceeded the recommended maximum weight on the coupling when the nose weight can fluctuate between zero and well over 200kg? How will it invalidate your insurance as I am not aware of any legislation governing nose weight for domestic trailer/caravans? The legislation involves the load on the rear axle.

Having said that it is always best to comply with recommendations and to stay within the law whatever you are using or doing!

 

[Lutz]

The Profs comments are valid but exceeding the noseweight limit is not, in itself, an offence. However, if noseweight is exceeded, it is more than likely that the maximum permissible rear axle load of the towing vehicle is exceeded, too, and that is an offence. Such a condition would also be picked up quite easily if the outfit is subjected to a roadside weight check.

 

[Buckman]

The Profs comments are valid but exceeding the noseweight limit is not, in itself, an offence. However, if noseweight is exceeded, it is more than likely that the maximum permissible rear axle load of the towing vehicle is exceeded, too, and that is an offence. Such a condition would also be picked up quite easily if the outfit is subjected to a roadside weight check.

To be clear the comments are valid, but explanation is over board and meaningless to many people who want a simple life without worries.

 

[ProfJohnL]

I am sorry, but you are going totally over board and your comments on the nose weight are probably not very valid. How will the manufacturer prove that you have exceeded the recommended maximum weight on the coupling when the nose weight can fluctuate between zero and well over 200kg? How will it invalidate your insurance as I am not aware of any legislation governing nose weight for domestic trailer/caravans? The legislation involves the load on the rear axle.

Having said that it is always best to comply with recommendations and to stay within the law whatever you are using or doing!

How have I gone over board with my comments? I have simple described the relationship between a static load and a dynamic load using what I understand is the accepted industry peak load differential identified by Lutz.

The reason I explained it is your posting at #58 where you declare that you have chosen to exceed the manufacturers "S "value, and say its not a problem, tacitly encouraging other readers to ignore such limits. You appear to use the argument that becasue the S value is not a specific legal limit there are no consequences to exceeding it.

Well there are possible consequences.

How many times have we had reports of caravan manufacturers refusing to cover a collapsed suspension under warranty, becasue the manufacturer has declared (without proof) the caravan has been overloaded. The difference here is you have declared publicly in this forum that you have exceed the stated S value for your car or caravan hitch. If a caravan manufacturer were to link your avatar to your real name, they could use your declaration as evidence against any warranty claim you might make.

When you take out car insurance, the policy covers the vehicle (and trailer) on the assumption that it will be used within the manufacturers loading specifications. By deliberately exceeding the nose load specification, you are not using the vehicle within its manufacturers specification, and this could give the insurer due cause to withdraw or void your policy.

If you were stopped for a roadside inspection, whilst the fact your nose load is in excess of specification and that is not an offence in itself, it could be deemed as having an unsafe vehicle or load. Otherclive has previously reported that roadside checks can include assessment/calculation of nose load.

Suggesting exceeding any manufactures' specification is irresponsible.

To be clear the comments are valid, but explanation is over board and meaningless to many people who want a simple life without worries.

Whilst it is preferable to offer a simple solution, sometimes it is necessary to to provide an explanation involving details, becasue the devil is in the detail.

The simple solution to excessive nose load, is to trim to an acceptable load that is within the manufacturers specifications.

 

[Buckman]

Does anyone really care about the difference between a static and dynamic load? Once again going over the top with an attempted explanation with numerous falsehoods regarding my posts and making unnecessary accusations! Maybe with a bit of luck a moderator will shut down this thread as it is going nowhere except around in circles.