Quote: Originally posted by jhsw on 25/11/2011<P style="MARGIN: 0cm 0cm 0pt" class=MsoNormal><SPAN lang=EN-GB><FONT size=3 face="Times New Roman">Hi All, An interesting bit of reading, up grade in weight in this topic,( in a nut shell), would I be right in thinking that when a vehicle chassis and suspension are designed, they are designed to take a specific weight, (say for example), it is designed to take a max of 1600kg, and is plated for say a max of 1400kg the 200kg weight difference is the built in safety margin (same as car to caravan ratio of 85% kind of thing), and it is that weight difference that is eaten into, to up grade the caravan weight by a few extra kilos, and still keep within the legal requirements, or am I totally off the mark here. Interested in the replies. </SPAN>
Not got a lot of time to think my answer through fully as I'm on my way out - perhaps someone else can take this one over today.
In a nutshell, it's a lot to do with marketing. Caravan manufacturers can sell vans more easily if they are percieved to be lighter. the heavier the van, the more restriction you have as to the vehicle you can use to pull it. The MTPLM is the maximum weight you are allowed to tow - including anything you put into the van. It is the MTPLM that is used to decide if you are 'legal' (that's another story). So your car may 'legally' be able to tow a van of 1435kg but not 1500kg. A manufacurer will plate the MTPLM as 1435kg because less vehicles will be able to tow a van with an MTPLM of 1500kg.
The difference between the two weights is literally, the weight of the items you are allowed to put into the van. The van itself is the same, but it is the MTPLM plate which is the starting point for 'the law'. If your car says you can't tow a van with an MTPLM greater than 1435kg, then if the van is plated as 1500kg, then you can't 'legally' tow it, even if it's empty and if in practice it only weighs 1300kg.
It's a bit more complicated than that too. Notice I have used some words/phrases in inverted commas. These words/phrases are not strictly speaking the correct words and phrases, but they are the best I could come up with in the short time I have to answer this post.
I hope that might have shed some light on the problem, but I may have totally confused people too. This is what I understand the situation to be. Much is down to interpretation, so no doubt someone will be putting another view soon.
Hi David, I understand what you are getting at, I am aware of the MTPLM, the pay load, and any combinations of car and caravan, up to the max MTPLM, and understand the reason caravan manufacturers want their van to be more appealing to potential customers, but that is not what I am getting at, my question was where do the get the extra kilos from,If a chassis and suspension is designed to take a max weight of 1600kg before structural failure, then you can not increase this to 1625kg, but if chassis and suspension is designed to take 1600kg, and then plated for 1400kg, that is 200kg built in safety margin weight before chassis and suspension failure, this is what I presume that the caravan manufacturers use to increase the plated max, from 1400kg to say 1450kg, still leaving 150kg safety margin for that chassis. The chassis has to be designed to take more than the plated weight in order to increase the plated weight, caravan only irrespective of any tow vehicle. Hope I have made this a bit clearer.
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hi, yes some are made to be alot heavier than they end up.
in trucks it can be 4 or 5 tons the chassis gets down plated to in the factory.
its often just plates under bump stops that lowwr the weights .
many 10 ton dafs get lowerd to 7.5ton you just have to put the right size metal plate under the bump stop .and paint it yelloew . if its not yellow it wont be down plated. thats life follow the rules all ok.
trailers very often get used on lighter aplications because its not sworth designing another one . use what they have it will be strong enough . if you know the differances its just a paper exercise to up plate. some companies thats all they do chassis alterations up and down.
i voluntary drop 2tons off my trainweight on my mini artic just so others can drive it on a old car licence. notify dvla and get a new plate made. i can up it again just as easy.
Most of the Bailey single axle vans use an Alco frame that has a max rated MTPLM by design of 1500 KG (the safety margin is on top of this) - as has been stated by a number of posters most of the vans they produce actually weigh less than this to increase the range of cars that can tow them.
Some of the single axle Unicorns have a specially uprated frame and running gear with an MTPLM of 1600 Kg but again are usually rated lower to increase the range of cars.
I have just picked up on this post, must admit to being somewhat surprised. I always assumed to have the caravan MTPLM uprated that it's suspension had to upgraded.
I also take on board that it has to be done by the book to comply with the law, otherwise it may well come back and bite you.
i think we must also not take it for granted that it is just a paper exercise . many do need suspension or tyre upgrades . just looking at thev tyre markings are the clue there. check all mrkings with a tyre check list. alway check with the manufacturers . except if using a chassis specialist . they very often have the build of vehicles and caravan specs. they pay for upgrade info every year. be safe .be carefull.a telephone to makers is always cheaper than a fine.
........my question was where do the get the extra kilos from,If a chassis and suspension is designed to take a max weight of 1600kg before structural failure, then you can not increase this to 1625kg,
but if chassis and suspension is designed to take 1600kg, and then plated for 1400kg, that is 200kg built in safety margin weight before chassis and suspension failure, this is what I presume that the caravan manufacturers use to increase the plated max, from 1400kg to say 1450kg, still leaving 150kg safety margin for that chassis.
The chassis has to be designed to take more than the plated weight in order to increase the plated weight, caravan only irrespective of any tow vehicle. Hope I have made this a bit clearer.
I agree totally with what you have written - this is the way I understand it. Sorry I misunderstood what you were asking.
Hi vwalan, thanks,I thought that would be the case, “yes some are made to be a lot heavier than they end up. in trucks it can be 4 or 5 tons the chassis gets down plated to in the factory. its often just plates under bump stops that lower the weights.”
Hi David, no problem, I should have made it clearer to start with.
------------- If everything runs smoothly then I must have done something wrong
If in Doubt Check it Out.
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Topic: re weight plate
