Peugeot 5008 70kg Noseweight - Caravan Match

[ProfJohnL]

Hi Prof. I agree that loading towards the back is not always a problem but it needs a lot of care and to me is best avoided. In this case it is possibly too late but personally I would not buy a car where the nose weight allowance was that low.

Hello Ray,

Which ever car a person chooses provided it meets the required legal and technical specs for towing their caravan is a matter of personal choice. If an outfit is acceptably stable with a 60 to 65 nose load, you do not need a greater to bar nose load limit. It would be illogical to reject a vehicle that meets all the required technical points and other good advice just becasue it has 70 rather than 75 kg or greater nose load limit. What benefit is there to have a greater value than you need?

 

[Buckman]

On many outfits you can carry bicycles on the rear as the caravan has a purpose built bracket for this. I would think that the load at the rear may affect handling even if perfectly balanced?

 

[otherclive]

On many outfits you can carry bicycles on the rear as the caravan has a purpose built bracket for this. I would think that the load at the rear may affect handling even if perfectly balanced?

Then its not the noseweight limit that is the potential problem. Putting bikes on teh back is little different to carrying heavy kit (circa 35-40kg) in the rear end of the caravan, although the bikes CoG would be higher. If it necessary to carry bikes there are other options such as the cars roof.

 

[Craigyoung]

On many outfits you can carry bicycles on the rear as the caravan has a purpose built bracket for this. I would think that the load at the rear may affect handling even if perfectly balanced?

We carry on our bikes on the back quite a bit on a proper carrier and not once have I noticed any difference in the steering or the capability of the car .

 

[Raywood]

With two bikes and the rack what weight have you taken from the loading allowance?
Apart from not wanting the weight right at the back, I doubt we could do that and stay within the MTPLM.
Like the number though.

 

[otherclive]

With two bikes and the rack what weight have you taken from the loading allowance?
Apart from not wanting the weight right at the back, I doubt we could do that and stay within the MTPLM.
Like the number though.

Sprites have a reasonable payload, which some other models of caravan don't have. To some extent the more upmarket the model the lower the useful payload.

 

[Craigyoung]

Ray ,

Like Clive says , our Sprite payload is quite generous at about 225 kg , the bikes are a light weight to but I think the rack will take up to 6o kg. The only other add on before our packing is the mover which we had fitted which was a must given the size of the van !

Craig .

 

[ProfJohnL]

On many outfits you can carry bicycles on the rear as the caravan has a purpose built bracket for this. I would think that the load at the rear may affect handling even if perfectly balanced?

I know this is perhaps a little off teh OP's topic, but one strategy to bring about an acceptable nose load may involve some form of end loading.

There are many variables that will have some effect on the outfits handling. End loading is one that may have the potential to make a noticeable change, but it obviously depends on how much the loading is changed, as well as other things like the type of roads you are towing on, your speed, weather conditions, especially wind speed and direction and other traffic. So its would be difficult pin any handling changes solely on end loading unless its was a very significant change.

The University of Bath, did some work sponsored by Bailey Caravans of Bristol which resulted in a model to demonstrate the effects of trailer loading.

https://www.youtube.com/watch?v=PFzrWHTG5e8
The model had the ability to slide the applied load at various points along the trailer longitudinal axis, and the public demonstrations showed it with the entire load clustered over the main trailer axle, or with the load split roughly equally and positioned at the extreme ends of the trailer.

The results were dramatic. and it laboured the point about NOT end loading. However whilst the model admirably demonstrated the effects and influence of trailer yaw inertia, the model did not realistically represent the reality of caravan construction and the distribution of mass
was demonstrated going from one extreme when the entire load was centered over the axle to splitting the load and placing it at the extreme ends of the trailer. The model was very dramatic, and it certainly points to the need for sensible loading

But, the problem here is, the model does not accurately represent a caravan. The bulk of the mass of a caravan is in its construction, and all we can add is 2 or 3 x 100kg as pay load. So there is no way the whole mass of the caravan would sit at the extreme ends of the trailer. So the model is over sensitive, where as a real life caravan would not be so readily upset and its far less likely to have such dramatic outcomes.

Having made that observation, there is no doubt that every effort to keep yaw inertia to a minimum is an important safety strategy for loading caravans. but in most cases some end loading is not going to be catastrophic.

 

[Lutz]

Just to add a further comment to ProfJohn's notes, the model used to demonstrate the effect of end loading was very extreme, from load distribution above the axle to relocation of the entire load at the ends and nothing over the axle. Such an enormous change of conditions would never be encountered in practice, even if a fully loaded bicycle rack is added at the back. In a real live situation the conditions will be somewhere in between, so it is difficult to make a categorical statement regarding end loading.

 

[Raywood]

I accept that the model is extreme. It does however help to demonstrate the problem as long as you understand that it is extreme.

 

[ProfJohnL]

Hello Ray.

The point of the demo was to show how Yaw inertia in a trailer was affected by the distribution of the mass. The demo certainly managed that quite spectacularly, and you can see the spectators being quite surprised by the effect.

Something else which the demo did, but was not explained, is the fact you can see the axle of the caravan is located at what appears to be exactly halfway between the hitch and the end of the main longitudinal beam. This would mean the bare trailer with no added weights would be virtually balanced with no appreciable nose load. But if you look at the weight that have been loaded, the stack to the rear has about 50% more discs than the front stack. This means even with the loads close to the axle, the car will be experiencing a negative nose load. But even worse is when the loads are moved the rear load is displaced further away from the axle than the forward load exacerbating the imbalance of the load and increasing the negative nose!

This model is so far from reality that it should carry a warning. However even though it is not a realistic analogue of a real caravan it does show how yaw inertia can start to affect affect towing, But it should also have pointed out that every caravan has some amount of end loaded mass from its body work and fittings, and that different layouts will have different amounts of mass, but in general the degree of end loading from the caravans construction should not cause catastrophic instability, and indeed there is some considerable latitude within the design of a caravan to cope with modest or reasonable amounts of payload in rear lockers etc. if for nothing else but to trim and control the developed nose load.

I would suggest that Trimming a nose load by end loading should be a last resort, when other load distribution strategies have come up short.

 

[Raywood]

Hi Prof, Cannot argue with that.