New book on caravan stability

[KeithB]

Has anyone seen Collyn River's new book: 'Why Caravans Roll Over And How To Prevent It".
Confession here. I helped him proof read it. But it's a really informative read for anyone interested in safe towing.

https://www.rvbooks.com.au/page/bookshop/

Keith

[tryagain]

Would likely be a good read... But as I don't have a caravan and am a tight arse I'll pass on it for now!

[KingBilly]

Can you give us an “executive summary”?

KB

[Bird]

Can you give us an “executive summary”?

Dont have too much weight up high
Dont tow like your driving a race car on windy roads,

If theres 25,000 cars behind you cause your doing 30 under the speed limit, its time to pull over and let them by.
 

[KeithB]

Can you give us an “executive summary”?
KB

There's a lot in the book and I don't want to steal Collyn's thunder over a book that costs less than twenty bucks.

He talks about the centre of gravity and the increased yaw moment that comes from loading excessively to the front and the back as well as the instability that comes with weight differentials, low ball weight, poor water tank placement, excessive caravan length and low roll centres, all of which he explains in some detail. Independent trailing arm suspension gets a bit of a panning, which a lot of readers won't like but which I agree with.  He also discusses the importance of overhang to the tow point Vs wheelbase and gives examples of good and bad. My 200 Series, it seems, is not so good in that department. He devotes a lot of time to discussing the slip angle of tyres and I started out wondering why. Slip angle determines grip and he says that the big enemy of stability is oversteer which is made much worse by not adding 5-10 psi to the rear tyres of the tow. He also suggests changing the tyre pressures on dual axles.

There is a whole lot of other stuff about critical speed, the limitations of modern caravan stability control, weight distributing hitches, busted ute chassis, the dynamic and confusing effects of wind from passing trucks, to name a few. One of the most interesting parts of the book is a short self evaluation quiz where you allocate points for each answer and your tally tells you how you rate on stability. That was an eye opener. Each chapter has a concise summary of the material and there are plenty of informative illustrations.

A lot of us are already doing some of the right things but how many of us understand WHY they are right? Collyn's book provides the missing insight. Twenty bucks for a chance to increase the safety of the family is a no brainer to me.

Keith

[KingBilly]

Thanks Keith.  Sounds like it is a worthwhile purchase.

KB

[topcat]

Thanks for the summary- in this age of available information, ignorance is a choice
TC

[tryagain]

Here is an article that touches on a few of the points Keith mentioned were in the book obviously no where near as in depth as the book would go though. https://www.caravancampingsales.com.au/amp/editorial/details/how-to-avoid-a-roll-over-59135/

[Troopy_03]

https://www.exploroz.com/vehicle/caravans/caravan_dynamics.aspx

https://practicalmotoring.com.au/car-advice/everything-you-need-to-know-about-towing-heavy-trailers/

[Metters]

I already have two of his books.  One is on camper trailers but it getting on in age and I think he now has an updated one.  The other is solar for vans/trailers etc.  Both are excellent and while I don't own a caravan, I will be buying this new one.

Independent trailing arm suspension gets a bit of a panning, which a lot of readers won't like but which I agree with.

I also agree with him.  When you look at the way a trailing arm suspension works and how it and the wheels lean over from ground level when the van leans, it would be hard to find a design that could be any worse.  They also have too much unsprung weight.

On the other hand they are cheap and easy to make and look a million dollars to anyone who does not have any idea of how any suspension design works.  That would be the majority of caravan buyers.

[tryagain]

I don't think many people who understand how it works dispute that a beam axle has a far better roll centre than independent trailing arm suspension, I think the question in my mind is how much effect this has in the real world, the reality is the degree that it will affect differing setups to different extent.

Just about all van rollover video's I have seen however don't involve high offroad van's with trailing arm suspension, I did follow one on a highway once however and it was moving around a heap and looked scary. Whilst I agree that from a roll centre perspective, trailing arm suspension is worse, I am not yet convinced that it plays a big part in rollovers (in comparison to the other factors) and therefore, on the whole, when taking into account other advantages isn't a decent option. The bigger the van, however, the bigger of an issue it is going to be.

I am however looking forward to seeing how Keiths suspension performs as I have always liked the look of it and Collyn had some input into it, incidentally I think the Bruder has some similarities to it but is an independent trailing arm design and that seems to be one of the main features that they push. 

[KeithB]

I am however looking forward to seeing how Keiths suspension performs as I have always liked the look of it and Collyn had some input into it...

Collyn didn't have any input into my suspension design because I met him well after it was built.  It's not an original design by any means and has been around for more years that I have. My one regret is not having enough room for a Watts linkage rather than the Panhard rod I opted for.

Keith

[GBC]

Very few manufacturers finish off high COG vans on independent suspension with sway bars. They are available and should be mandatory based on engineering calcs but the van industry is pretty far from that sort of normalisation. Such a simple thing which is too often overlooked.

[Metters]

Very few manufacturers finish off high COG vans on independent suspension with sway bars. They are available and should be mandatory based on engineering calcs but the van industry is pretty far from that sort of normalisation.

Unfortunately the van industry is in the same position as the car industry was in the early years of motoring.  There was far too many manufacturers and few if any had the resources to go deeply into critical areas like suspension design.  Cars were little more than horse drawn vehicles with an engine and no horse.  When engine development started to expose major flaws with suspension design, it took a company the size of General Motors to do something about it.  This man was the one who set the industry on a path that has given us the suspension designs and handling charastics that we have today.  http://www.millikenresearch.com/MauriceOlleybyWFMilliken.pdf

Today caravan suspensions are in need of the same degree of attention but there are around 100 manufacturers in this country and I doubt if any of them could afford to sign up another Maurice Olley to head a team of engineers to improve their suspensions. 

Sway bars may help on trailing arms but they don't just keep a car a little flatter in corners.  They play a major role in transfering weight in corners and those increased or decreased loads on the suspension also change tyre slip angles.  Those angles control underster and oversteer.   

When you look at that list under the heading "Concepts Developed" in the link to Olley, it is not hard to see that the the whole thing is far more complicated than it looks.

[tryagain]

Collyn didn't have any input into my suspension design because I met him well after it was built.  It's not an original design by any means and has been around for more years that I have. My one regret is not having enough room for a Watts linkage rather than the Panhard rod I opted for.

Keith

Thought I'd read it somewhere but must have gotten muddled up, a Watts linkage is nice but don't think your Panhard rod set up will have any noticeable drawbacks.