The rise of caravan airbag suspension

AL-KO's recent release of its new auto-levelling off-road airbag suspension is the first major collaborative fruit since purchasing a number of chassis rivals in recent years.

But it is joining, rather than leading, the move to airbags as the preferred springing for serious off-road caravans.

Airbags in one form or another, have been around since the 1950s on luxury cars and on many truck, trains and aircraft since the 1940s.

Their increasing popularity on caravans is due to them offering a cost effective way to achieve an adjustable spring rate and improved braking and steering by keeping the vehicle’s wheels more firmly planted on the road.

Air suspension consists of a conventional suspension axle set-up with one major difference: air-filled conical reinforced rubber bellows are fitted instead of leaf, torsion bars or coil springs.

The air springs are matched to offer correct spring characteristics according to the weight of the caravan, and are usually supplemented by shock absorbers to control rebound.

There are a few versions of air suspension available; starting with the basic set-up that requires pumping up and deflating the airbags manually, usually using a portable air compressor, with inflation and deflation managed by a car tyre-like valve.

Also read: Do you need airbag suspension?

In more sophisticated and expensive systems, the air springs are filled from a separate air reservoir tank fed by an on-board air compressor, that can be operated manually to raise or lower the RV, either up and down, or side to side.

The better units also have a pressure regulator that automatically triggers inflation of the air springs if they fall below their required pressure or set ride height, aiding stability when cornering.

In another application, air springs have also been used for many years to control droopy tails on 4WD tow cars that often sag under the weight of a heavy caravan ball-loading. In most cases, the air springs supplement the factory suspension seat-up on these vehicles and are manually inflated before hitching up.

Toyota LandCruisers are typically tuned for a comfortable off-road ride for mining company executives and are therefore a little soft in the rear-end for serious heavy vehicle towing without ‘lift’ kits fitted by after-market suspension specialists.

In the United States, air suspension is beloved by custom car builders, who use it to drop one end or the other of a large car to within millimetres of the road, then raise it again on the move.

Leading the caravan airbag brigade

While most premium caravan manufacturers brands liked Bushtracker, Trakmaster, Bruder and others, offer air suspension on their top off-road models, Vehicle Components popularised the system for many caravan manufacturers when they introduced height-adjustable airbag springs for their popular ATX off-road suspension.

While standard bellows-style airbags still feature on the current Cruisemaster XT Air range, its latest, top-spec ATX suspension uses a rolling sleeve type air spring, like that used in the trucking industry, which offers more travel of the swinging arm without over extension.

Displayed in prototype form at the Queensland Caravan, Camping & Touring Supershow, the new ATX suspension will be available in coil spring, coil over airbag and rolling sleeve airbag configurations, with a maximum load rating up to 2800kg for single axle and 4500kg for tandem axle versions.

Now that the Auto Pacific Group owns Cruisemaster, the Queensland manufacturer can be seen as the development arm for its serious off-road suspension systems.

Controlling the ride and side-to-side height of these systems can be carried out via a remote controller that lives by the driver’s seat, with minor adjustment possible ‘on the fly’, reverting back to normal pre-set travelling height once you pass 25km/h. This is a particularly handy feature when crossing severe rocky ground, or when fording creeks.

The suspension’s side-to-side height adjustment is also useful when setting up camp on uneven ground, as your van can be levelled, even on a slope.  When towing our airbag-equipped Trakmaster Pilbara, we additionally used our Land-Rover Discovery’s three-height adjustable airbag suspension to first level the van fore and aft before making side-to-side refinements.

Being able to lower the suspension on one side also makes it possible to ‘lean’ the caravan away from trees that would otherwise block sharp turns on bush tracks.

Next level airbags

Queensland expedition caravan specialist Bruder has taken air bag springing to the next level, with large suspension movement possible on each of the two axles on its latest EXP-8 expedition models, allowing it to maintain a level ride across challenging terrain.

Then there's the Victorian-designed and built CRZR airbag suspension, currently only offered on custom-built CrzrVans and the Optimum CRZR edition by Masterpiece Caravans.

According to CRZR Industries founder Rhys Conti, the growth of the extreme off road suspension segment is further driven by the need for peace of mind by relatively inexperienced travellers.

“Once you embark on this level of build you inherently encourage a degree of over engineering," says Conti. "People want the security of reliability and trouble-free travelling in remote areas."

 “For example, our solid axle air ride suspension fitted to the ‘Optimum CRZR edition’ by Masterpiece uses a 65mm solid axle reinforce with a truss style Panhard bracket, trailing the chassis with JMACX billet radius arms riding on Firestone airbags with 12 inches of travel from Airbag Man.

“All our laser cut components are designed and fabricated in-house to create a suspension package that when in a tandem configuration is capable of carrying well over its 4495kg stated load capacity. 

“Perhaps that’s over-kill, but you don’t really know what today’s new breed of Outback travellers are going to go, carry, and do!"

“When I set out designing our extreme off-road suspension set-up it baffled me that everyone demanded a bulletproof solid axle set-up like that found on a 70-series Landcruiser or Jeep Wrangler, but when they wanted an off road trailer or caravan, all of a sudden they insisted upon softer independent suspension with dual shocks.

“I thought this was a backwards way of thinking and I set out to design something that had the strength of a solid axle, but could also be set up on airbags for ride quality and adjustability once at a campsite.

“As a result, our CRZR Industries solid axle suspension system is almost maintenance-free, with no need to ever perform a wheel alignment – just tyre rotation, bolt torque checks and brake adjustment are required.

Driving up the cost

So, why don’t all true off-road caravans have air suspension? Cost.

Complete systems on new caravans can add $5000 or more to the price of a new caravan. This puts it in heavy competition with many off-road caravan ‘luxuries’ and while most manufacturers now offer airbag suspension, the take-up is far from universal.

However now with AL-KO's and Cruisemaster’s latest decisive moves into this market and the clout both wield with many Australian manufacturers, it seems only a matter of time before air bag suspension becomes the accepted ‘norm’ for serious off-road caravans,

More significantly, without air springing. it will become harder to sell second-hand serious off-road vans in the years to come...

Related: Do you really need a caravan with the lot?