Rather than pollute another thread. I am responding here to a comment in the New MOT Rules thread, this comment from Lappy caught my eye.
Lappy
One of this forums jobs is to offer good advice, but ultimately it is always the drivers responsibility to ensue their vehicle (and any trailer in tow) is in a fully road worthy condition.
It is arguably the case that if allow any of the manufacturers load limits to be exceeded, your vehicle or outfit could be deemed to be unsafe, even though it might not be heaver than permitted.
It is a mechanical and scientific fact, if any aspect of the way a vehicle or trailer is loaded is changed, it will affect things like nose and axle loads. Most caravanners will find the way they load a caravan will produce different nose load values on outward and return journeys, simply becasue you will have used some gas, the loo may be heavier, there will most likely be less food. Clothes for washing may stowed differently You may have collected holiday memorabilia, maps, magazines etc etc etc... Whilst I agree its unlikely that any of these as individual items will make a big difference to the nose load, collectively there could be quite a shift, moving from safe to unsafe. I'm not just talking about over loading, some shifts could reduce nose load and increase the risk of instability.
Consequently just checking your nose load once, and then never bothering to do it again is shear bad advice.
It is well establish that having insufficient nose load can lead to early onset instability, so it is common practice to set a nose load towards the top of the available range. For those who aim for 90 to 95% of the available range the changes I have outlined above could very easily take the nose load to 100% or more.
Some caravanners on this and other forums have demonstrated a foolish disregard for the importance of observing nose load limits. The limits are there for an important reason. The manufacture decides if a vehicle is suitable to be used for towing. They have to set limits to make sure that whatever is hitched up is not going to cause the tow vehicle to become inherently unsafe or illegal, nor is likely to be damaged by the loads they tow.
Without going into too much detail if you have stationary mass of 1kg and subjected to gravity (an acceleration) at 1G, it produces a force of 1kg of weight. If you increase the acceleration due to some motion, then the mass will will produce a force of Mass x Acceleration. Newtons second law of motion Force = Mass x Acceleration.
Put simply. if you exceed your static nose load capacity by 10Kg that will translate to a much greater dynamic over load when subjected to the accelerations (mainly vibrations) caused by towing. When you consider that through tetsing at MIRA near Nuneaton that g forces acting on a caravan when being towed were measured and can normally reach 4G and frequently 8G and occasionally higher, overloading a static value can have serious consequences, including increased wear and tear, taking systems outside of normal expected limits, even mechanical failures.
Overloading any manufactures limits is a mugs game, so check your nose load before each trip.
Lappy said:
Lappy
One of this forums jobs is to offer good advice, but ultimately it is always the drivers responsibility to ensue their vehicle (and any trailer in tow) is in a fully road worthy condition.
It is arguably the case that if allow any of the manufacturers load limits to be exceeded, your vehicle or outfit could be deemed to be unsafe, even though it might not be heaver than permitted.
It is a mechanical and scientific fact, if any aspect of the way a vehicle or trailer is loaded is changed, it will affect things like nose and axle loads. Most caravanners will find the way they load a caravan will produce different nose load values on outward and return journeys, simply becasue you will have used some gas, the loo may be heavier, there will most likely be less food. Clothes for washing may stowed differently You may have collected holiday memorabilia, maps, magazines etc etc etc... Whilst I agree its unlikely that any of these as individual items will make a big difference to the nose load, collectively there could be quite a shift, moving from safe to unsafe. I'm not just talking about over loading, some shifts could reduce nose load and increase the risk of instability.
Consequently just checking your nose load once, and then never bothering to do it again is shear bad advice.
It is well establish that having insufficient nose load can lead to early onset instability, so it is common practice to set a nose load towards the top of the available range. For those who aim for 90 to 95% of the available range the changes I have outlined above could very easily take the nose load to 100% or more.
Some caravanners on this and other forums have demonstrated a foolish disregard for the importance of observing nose load limits. The limits are there for an important reason. The manufacture decides if a vehicle is suitable to be used for towing. They have to set limits to make sure that whatever is hitched up is not going to cause the tow vehicle to become inherently unsafe or illegal, nor is likely to be damaged by the loads they tow.
Without going into too much detail if you have stationary mass of 1kg and subjected to gravity (an acceleration) at 1G, it produces a force of 1kg of weight. If you increase the acceleration due to some motion, then the mass will will produce a force of Mass x Acceleration. Newtons second law of motion Force = Mass x Acceleration.
Put simply. if you exceed your static nose load capacity by 10Kg that will translate to a much greater dynamic over load when subjected to the accelerations (mainly vibrations) caused by towing. When you consider that through tetsing at MIRA near Nuneaton that g forces acting on a caravan when being towed were measured and can normally reach 4G and frequently 8G and occasionally higher, overloading a static value can have serious consequences, including increased wear and tear, taking systems outside of normal expected limits, even mechanical failures.
Overloading any manufactures limits is a mugs game, so check your nose load before each trip.
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