Apologies I should have edited better as I was asking about the stiffness of the caravan suspension?
In point of fact to reliably resolve a TA's weight you would need the Reich and 3 equal height pads each positioned under the three road wheels not being measured on the pass.
The stiffness of the suspension would affect the the degree of load transfer to the other wheels when one or more wheels are lifted, which is why there is no way Reich could engineer compensation into the system. There are simply too many variables, some of which you cannot know or work out without some extensive calculation or measurement.
I don't feel you've had a complete answer to your question yet. Neither is this going to be a complete answer, but maybe does go a bit further in answering your question.
The spring part of a suspension is there to support the load, and to provide compliance, so that if a moving vehicle hits a bump then the impact of that isn't totally transmitted through into the vehicle. The spring, and the suspension, has a static spring rate. That means if you add say 100kg of weight to it, then it will compress a certain distance. Add 200 kg and, if it is a linear rate, it will compress twice as much.
If the suspension is a pure spring then the problem is that once it's started bouncing, it can pretty much keep bouncing forever. Another problem is that if you hit a bump that uses up all the spring travel, then you are still going to get a big impact force transmitted through to the vehicle. So all real suspension systems have added damping. Dampers cut down on the bouncing oscillations, and also have the effect of increasing the 'dynamic stiffness' of the suspension. They don't have any effect on the 'static stiffness' (ie the deflection of the suspension when you add weight when its stationary). But damping does mean that if the suspension sees a shock force then it behaves like a much stiffer system and cuts down on those nasty shock impacts.
Caravans typically have a 'rubber in tube' suspension, which has a bit of damping already because of the characteristics of rubber and friction and so on. So chassis manufacturers like it because it's cheap, and sort of does the job. (But if it was fitted to your car, you'd find the ride to be awful). By adding hydraulic dampers, you're making the suspension more sophisticated and capable, reducing events when a wheel crashes up to its limit of travel and I'd anticipate that you'd be extending the life of the axle assembly.
(I said this wasn't going to be a complete answer - so please don't come back at me for not saying anything about effects on roll stiffness and handling and anti-snaking etc.....!)
The effectiveness of caravan dampers in mitigating shock is less than obtained from car dampers. See the links in #22 of the link below.
forums.practicalcaravan.com
Over loaded axel!
We read on here from from time to time o out caravan suspension that collapses and damages the wheel arch and owners being told it is their fault for overloading. I have just found the info about Alko caravan axles. Perhaps I am missing something . LINK And the relevant part being. John
Thanks for all the help with this one folks, highly appreciated 👍
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