RV Books

RV Books provides powerful, proven & unbiased information on caravans, motorhomes, camper trailers choosing, buying, using and building. This RV Books website is currently in process of major change and updates - this will happen in late May - do not be surprised to find it is totally different.

Instant, powerful, unbiased & accurate information & advice on caravans, motorhomes, camper trailers and fifth-wheel caravans.

RV Books helps current and future caravan, motor home, camper trailer and fifth-wheel caravan owners understand, buy, maintain and enjoy all types of RV. Here are general & technical RV articles, videos and influential RV blog. Plus our own proven digital and printed RV Books written by Collyn Rivers. It also features long-proven work of other RV authors.

RV Books sells eBooks directly. If you would like to buy a print version, please see here.

Please note: Almost all articles have now (February 2020) been updated - and will continue to be as needed. 

Both caravan and home solar is also covered our companion site solarbooks.com.au

All books are in eBook (pdf) format

The Caravan and Motorhome Book

by Collyn Rivers

(eBook A$29.95)

A detailed analysis for buyers and owners of caravans and motorhomes

Why Caravans Roll Over

by Collyn Rivers

(eBook A$29.95)

Explains in detail every aspect of tow vehicle and caravan stability.

Caravan and Motorhome Electrics

by Collyn Rivers

(eBook A$29.95)

A technical but accessible guide to all aspects of RV electrics.

The Camper Trailer Book

        by Collyn Rivers

(eBook A$29.95)

Essential yet simple and proven reading for buyers, builder & owners of camper trailers.

Solar That Really Works!

by Collyn Rivers

(eBook A$29.95)

This factual, simple & long proven book explains all you need to make solar first time for you.

The RV Handbook

by Collyn Rivers

Publication scheduled for early 2020 

The first ever fully comprehensive guide to RV purchase and ownership. 

General articles on a range of important topics relating to RVs.

Technical articles to assist RV owners, manufacturers and legislators.

Visit our online bookshop to buy all our books in print or eBook format.

Featured Article

Why Caravans Roll Over - updated 14 February 2020

Why Caravans Roll Over

Updated 13 February 2020

Understeer and oversteer.

Why and how caravans roll over or jackknife is now totally  understood. The cause is basic and readily avoided. It is substantially  associated with the towing vehicle suddenly oversteering. This constantly updated article you are reading here is a brief precis of what happens, why and how to limit or prevent it happening.

Our full (plain English) book Why Caravans Roll Over - and how to prevent it explains all.

This, (our now the top selling book)  includes a simple Question and Answer section enabling you assess the probable stability of your own rig - and how to  improve that. 

Reader feedback show that the Q &A pages alone have assisted many improve towing stability, and (apart from buying the book) usually at no cost 

Caravan Roll Over Videos

In these caravan rollover videos, each caravan has become unstable with catastrophic results. They are unlikely to have occurred at a lower towing speed, but once they began to sway, they could not be recovered by driver correction (no matter how skilled or experienced).

Causes outside the driver's control include road conditions, wind resistance and gusting side winds (including those from trucks passing - or being passed).   

Factors within the driver's control include speed (particularly), weight of the caravan relative to the tow vehicle, distribution of weight in the caravan, tow ball mass - and tyre pressures of the towing vehicle. The use of a Weight Distribution Hitch too is involved.

That vitally required however is knowing how and why rollovers (or jack-knifing) occur.

Both videos show the accidents happened whilst towing on a flat road in a straight line. No bends, hills or obvious cambers. This is quite common but a particular risk is descending a steep windy hill at excess speed, and overtaking (or being overtaken by) a semi-trailer at high speed.

For the very first time, a full plain-English (plus a full technical explanation) is in our all-new book 'Why Caravans Rollover - and how to prevent it'.

                            The not-for-profit Caravan Council of Australia describes its as: Essential reading for all caravanners!'

Caravan Roll Over Factors

A caravan roll over is rarely caused by one issue. Several are usually involved. The ultimate cause - of the tow vehicle losing control I(tow vehicle oversteer) is outlined here.

A snaking caravan imposes side forces on the tow vehicle's rear tyres that can build up and cause them to lose all grip. If this happens at a speed (unique to each rig and its loading) these forces can trigger violently escalating snaking that often in a jack-knife.

The tow vehicle and trailer is usually travelling at high speed when a roll over happens. This is often when overtaking another vehicle, being overtaken or travelling at speed downhill.

A rollover at 110 km/h involves forces over four times higher than at 50 km/h. It best not to exceed 100 km/h.

The following increases your risk:  

Incorrect Trailer Weight Distribution

Heavy loads at the extreme rear of a long caravan make it unstable. Keep all heavy items close to the axle/s. Carry rear mounted spare wheels in the tow vehicle - not on the rear of the caravan. 

Tow Ball Mass

Inadequate tow ball mass decreases the rig's critical speed at which jack-knifing is likely. With many locally-made caravans over about 5.5 metres with tow ball mass below about 7.5%, that critical speed is very likely to be as low as 70-80 km/h.  

Excess Tow Hitch Overhang

Excess tow hitch overhang increases both download and side forces on the tow vehicle's rear tyres. Excess hitch overhang is a recipe for swaying. Use a tow hitch with the shortest possible overhang, not a longer one that may be marginally easier to couple and uncouple.

Tow vehicle tyre pressures  

It is essential wen towing a heavy caravan to have its rear tyres at least 50-70 kPa (7-10 psi) higher than its front tyres. That alone will considerably improve towing stability and, in borderline cases, remove the need for a WDH.

The technical reason is that if rear tyre slip angles ever exceed front tyre slip angles, that caravan is all but certain to be triggered into a jack-knife. This is is now known to be the major cause of most caravan and tow vehicle jack-knifing accidents.  

Slip angles briefly explained.

A pneumatic tyre's grip on the road is partly frictional and partly molecular. Depending on tyre construction, pressure and loading, that area of tyre-tread that contacts the road is a more or less hand-shaped area called its ‘contact patch.

A tyre’s ‘slip angle’ is the difference between a pneumatic wheel’s direction of travel, and where its contact patch is seemingly pointing. Steering a wheel (or subjecting that contact patch to a side force) causes the contact patch to distort, resulting in the tyre steering the vehicle. As any side force can do this, a side force exerted on the tow vehicle’s rear tyres can (and does) cause seriously unwanted rear-end steering.

It is only when subjected to a side force that is greater than the contact patches’ ability to withstand, that a tyre will slide out of control.

Understeer and oversteer

All current road vehicles (except specialised rally cars) have front tyre slip angles intended to exceed those of the rear tyres. This effect is called understeer.

Understeer ensures the vehicle will automatically veer slightly away from any disturbing side force: including if cornering too fast. That, in turn, causes that vehicle to take up a slightly wider turning radius – thus automatically reducing the imposed side forces. Without a minor degree of understeer, a road vehicle needs constant steering correction.

The extent to which a vehicle understeers depends on its relative front/rear tyre’s pressure and the weight the tyres carry.  Too much weight at the rear of a tow vehicle (either within the vehicle or imposed on it by a heavy trailer) can increase the slip angle of the rear tyres (and thus sideways movement that occurs when a side force is applied). If/when this happens, that tow vehicle is literally steered by its rear tyres. This is why it is vital to have that higher tow vehicle rear tyre pressures to be substantially higher than its front tyres.

External Factors

These are factors over which a driver has no control. Most are harmless for passenger cars, but when towing, can be dangerous. These include:

A wind gust, which can be natural or caused by a vehicle coming in the opposite direction a wind gust (or increased or decreased (side) air pressure) as a result of overtaking or being overtaken steep road camber, which may ease a trailer off to the side of the road. Over-compensating for this can send a tow vehicle and trailer sharply towards the middle of the road adverse weather and road conditions.

The issue is not how a rig feels and acts in normal driving. It is how it behaves in abnormal driving. This may include swerving at speed to avoid a head-on crash, or a strong-enough side force on a bend and/or being passed (or passing) closely at speed by a semi-trailer.

Many owners of fundamentally unstable rigs have not experienced this simply because they have not been subject to such issues. But (increasingly)many are - over 300 rigs jack-knifed in 2018 alone. Many of those also rolled over.

Police and rescue staff commonly report the driver as saying 'it always felt so stable until then .....'.

Our now top-selling book 'Why Caravans Rollover - and how to prevent it 'explains (in plain English) exactly how and why caravan rollovers happen. A invaluable section enables owners to estimate their own rig's stability - and suggests how to improve this. It also has a separate fully technical explanation - and many references.

The book is based on truly extensive research and (author) Collyn Rivers' having spent much of his life studying and working in this area. Collyn is an ex Vauxhall/Bedford motor industry research engineer.

Why Caravans Rollover - and how to prevent it is downloadable from this website. Buy it now!

Avoiding Caravan Roll Overs

'Why Caravans Rollover - and how to prevent it'  explains all

Major issues include:

never exceed 100 km/h with any rig where the laden caravan weighs more than the laden tow vehicle (especially when overtaking). 
do not overload your caravan (particularly at the rear)
make sure your tow ball mass is between 8-10%.
avoid having a laden tow vehicle that is lighter than the laden trailer. If it is, keep speed lower accordingly. 

Click HERE to purchase Why Caravans Roll Over
Why Caravans Roll Over is also available in a Kindle version available from Amazon.com.
For the Kindle version click HERE

Our influential blog on all things RV.

Towing Without a Weight Distributing Hitch

People are increasingly using caravans that, when laden, well exceed the laden weight of whatever tows them. It is, for example, not uncommon to see 2500 kg (laden) dual-cab utes towing 3500 kg caravans.

For on-road stability, a conventional caravan needs to be nose-heavy by 8-10% of its laden weight. When hitched to its tow vehicle that (typically 200-350 kg) pushes down on the rear of that vehicle. As with pushing down on the handles of a wheelbarrow, that levers up the front of the tow vehicle , thereby reducing the weight on the tow vehicle’s front tyres.

 Where that tow ball weight is comfortably within the laden tow vehicle’s payload, that front weight reduction is unlikely to cause any but a slight decrease in the understeer necessary for stability. Furthermore, that weight decrease is compensated by reducing tow vehicle front tyre air pressures (by as little as 14 kPa (2 psi).

A so-called Weight Distributing Hitch (WDH) may then be added to resolve the weight problem. If doing so, however, it fixes that weight problem - but introduces unwanted effects.

How a WDH works

A WDH is, in effect, a springy beam that, by levering up the rear of the tow vehicle, restores weight (down-force) from the tow vehicle’s rear tyres to its front tyres. 

While this seems a good concept, a WDH can only counteract the caravan’s tow ball downforce. Side forces (when the caravan yaws), however, are still imposed unchanged on the tow vehicle’s rear tyres that now (due to that WDH) are less able to counteract them.

The overall effect is to reduce the rig’s ‘cornering power’ by an appreciable amount. In extreme (but nevertheless encountered) circumstances, these side forces may cause that tow vehicle to oversteer. If that happens, a jack-knife is virtually inevitable. In all cases, the effect is to lower that rig’s stable top speed and often to below 100 km/h. That does not imply that the rig will inevitably misbehave at speed – but is more likely to if ‘hit’ by a strong enough side force. 

Reducing a WDH’s unwanted effects 

The above effect is inherent, but its extent can be reduced by adjusting the WDH to correct only 50% or so of the weight transferred. Check this by (before coupling up the caravan) measuring the distance between the top of the tow vehicle’s front wheel and the wheel arch. Then, with the WDH not engaged, coupling-up the laden caravan. Then adjust the WDH such that the distance is halved.

why buy a book?

We feature RV content from authors recognised in the Australian and New Zealand RV industries for their in-depth knowledge and independence. All books are free of advertising, and authors accept no payment to mention brands in their books. By purchasing a book, you are not only educating yourself but also supporting the work of independent RV writers.

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