guide to best suspension design for off road caravan

insert image here:

150 x 80mm

Suspension Design for an

Off-road Caravan

www.kimberleygroup.com.au

Copyright Kimberley Kampers Pty Ltd

20140103

Suspension can be raised easily before a water crossing with the ultimate in auto-ride height remote control air-suspension

2 Guide to Suspension Design for an Off Road Caravan

kimberleygroup.comCopyright Kimberley Kampers Pty Ltd

You can travel on virtually any road with any suspension. People do the Cape towing a low cost box trailer and tent. However, the poorer the suspension, the slower you will need to trav-el and take less load. It is all about energy. It is also about stability. The faster you travel and the heavier the caravan, the more important it is to have good suspension. If you want to travel long distances on the highway and then long distances in difficult off-road conditions with off-road caravans and camper trailers, then you should understand the impact of suspen-sion design. You deserve to have the smoothest travel with the best stability and the lowest fuel consumption possible… at the best pace!There are many design variables to support this but none has a greater impact than suspension design.Great suspension design can’t be done alone on a drawing board; it needs analysis of a dynamic model with the vehicle to get the “design constraints” right. This is something few manufacturers understand. The core question then when investigating your travel requirements is to ask just how much of Australia do you want to experience? “Experience” is more than just looking. It is not just soaking up the beauty of Australia, it is also living and sharing experiences.That’s great, but is it worth the additional cost? Have a read through this eBook to decide.

How much of Australia do you want to experience?


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Table of Contents

How much of Australia do you want to Experience?

1. Independent Suspension Innovation in 4WDs since 1970’s

2. Reliability

3. Digital Age adds to Stability as well as Reliability

4. The Difference with Caravans and Trailers.

5. Camper Trailers and Caravans pre-2000

6. Coil Springs

7. Coil Springs and Stability

8. Air-Springs (Air-bags)

9. Premium Air-springs

10. Roll Stability and overall Design

11. Ride Quality and Lowest Unsprung weight

12. Lowest unsprung mass of any suspension

13. Air Suspension Control Systems

14. Ride Height controlled Air Suspension Systems

15. Changing a Wheel /Tyre without a Jack

16. Driving on 3 Wheels in an Emergency

17. Anti-Sway Bars

18. 5 Year Warranty



Suspension innovation is probably the most important factor in a 4WD’s off-road superiority.In 1970, at a time when almost all 4WDs used primitive leaf springs, Range Rover pioneered the use of soft, long travel coil springs on all four wheels. This caused a lot of skepticism among off-road journalists. The result was a delay until 1987 introducing this feature to the USA for fear the market may not accept such innovation. The benefit of ex-treme axle articulation became clear to everyone.Other 4WD manufacturers started incorporating it some 5 years later. No one could then believe they were ever skeptical and this innovation became the norm!Then in 1993, Range Rover suspension design took another leap ahead into the next generation of innovation: electronically controlled, self leveling, variable height pneumatic suspension. (This is where we are today with off-road caravan air-suspension, some 20 years later)This gave the driver the ability to reduce ride height for high speed cruising, increase it for off-road clearance, maintain a level ride regard-less of load, and maintain articulation. The staggering capabilities of this system, in combination with the simultaneously introduced elec-tronic traction control, took the 4WD world by surprise.Now the Range Rover suspension innovation has progressed: The air-springs are cross-linked (left to right) when off-road, reducing the effec-tive spring rate to near zero. This not only softens the ride but increas-es the ground contact force and traction considerably on a drooping wheel. It also makes the independent setup simulate the articulation motion of a beam axle, getting around the usual criticisms of reduced effective off-road clearance on uneven terrain that independent sus-pensions usually receive. This is where we are heading at Kimberley but it will take some devel-opment and test time to get there.

Independent Suspension Innovation in 4WDs



Aside from the advantages of much-improved ride and steering con-trol over bumpy terrain, one of the difficult design constraints is the load on the vehicle and travel conditions. Using soft coil springs improves the ride until the vehicle load goes over the design limit and the coils are struggling to hold up. Then trouble is on the horizon.When air-springs (air-bags) were first introduced, the story was similar. The air-bags were rated at a maximum pressure and heavy vehicle loads pushed past this. Although Range Rover were using major manufacturers like Fire-stone for the actual bags, the fittings and compressor were not al-ways as reliable for the high duty rate.Overall, the market accepted the innovation but reliability stories held back overwhelming acceptance. The author has had 4 Range Rovers and whilst only one required some minor air suspension re-fit, it was expensive and could not be done “in the bush”.The designers have now understood that it is not just the actual “air-bags” that are the weak link in the system but all the fittings, com-pressor and tank that go with it. Reliability is now up to par with mechanical systems. Prices are now reasonable especially replacement air-bags which can be sourced in many locations around Australia.

Reliability



Digital Age adds to Stability as well as Reliability

The advent of computers embedded in vehicles has not only extract-ed that extra engine efficiency but significantly improved stability in today’s 4WDs.High end models can be equipped with an air suspension system featuring self-leveling, ride-height control and stability management. Stability Management is an electronic damping control system. It offers continuous adjustment of individual damping forces based on current road conditions and driving style – all from the centre console.During performance driving or heavy off-road use, there is an in-creased tendency for the body to sway. Stability Management pre-vents this from happening, thereby improving stability and occupant comfort. The system uses a series of sensors to monitor the move-ment of the body. It also gathers data on lateral acceleration; steering angle, brake pressure and engine torque and modifies the damping force on each individual wheel in accordance with the selected mode.Stability Management remains active at all times. It automatically adapts to the prevailing driving conditions, enabling greater car con-trol and improving comfort and safety.The auto-ride height air-suspension from Kimberley is digitally con-trolled and has a LCD display and optional hand held remote control.



Are trailers, caravans and campers trailer different in their design requirements to 4WDs?Yes, absolutely. The differences are so great, there are few vehicle suspension ex-perts who understand the nature of a towed trailer.It is one of the reasons for writing this eBook. There is virtually noth-ing published regarding “off-road caravan suspensions” and little that can be found on the Internet other than individual stories. We started by studying the theory of suspension in commercial trail-ers which is a closer starting point than most people realize.Our motto on innovation is: “Without understanding the theory, expe-rience will not teach”. So it has taken years of experience layered on top of the theory of suspension in trailers to get to this point.You will need to read to the last chapter to gain insight into the differ-ences.We believe you cant “add on” top of the line suspension. It has to be part of the design right from the beginning. So lets look at our journey to get to this point!

The Difference with Caravans and Trailers.



Leaf springs were common-place pre-2000 with most focus on the dampening of shock absorbers over the difficult terrain. Independent suspension was being used in higher end camp-er trailers.We had our own experience with leaf springs which we fitted to our “Escape” and early ”Sports-RV” models. The photo on the right shows the electric drum brake hub and Old Man Emu shock absorbers with a 7 leaf spring. Note the red “bump stop” was used in the leaf spring.This set up resulted in no spring failures.However, the load range for this type of suspension is limited. In the photo you will see a 300kg+ quad bike loaded on the front of the author’s Kimberley Kamper that had leaf suspen-sion. There was a 300mm jump to get onto this bridge!In poor roads and conditions, travel speed slowed to a snails pace and the rig jumped around like a kangaroo. Every bump was no-ticed and the tie down straps re-tensioned every 100 klms.

Camper Trailers and Caravans pre-2000



Whilst this is an extreme weight, it is the extremes that test the the-ory of our designs. After towing this, it was decided to leave the leaf springs and standardise on independent suspension for every mod-el. This has been the case since 2005.The one benefit of leaf spring suspensions is higher inherent roll sta-bility. This is now overcome and in fact surpassed in the coil and air suspensions by adding anti-sway bars.

The coil springs on a Kimberley Kamper go deep into the cups and the upper mounts for secure positioning. Inside the coil spring is a sewn web strap to prevent over extension of the shock absorber.In this photo you can also see secondary “bump stops” to also limit compression of the shock absorber. These secondary bump stops are polyurethane and compress at a higher spring rate to absorb any huge thumps on the suspension!The shock absorbers in this photo are Fox mono-tube.

Coil Springs



The main secret to the amazing off-road traction of independent suspen-sion with coil springs is to use excep-tionally soft springs. However in a 4WD with 4 available wheels, it is not uncommon to have one off the ground with the vehicle weight on the other 3. In a trailer, this rarely occurs. And this is one of the major differences to 4WDs : the high load is shared to each trailer wheel as they are rarely off the ground.As a result, the coil springs on the trailer have to be matched to the load. If you travel on one trip with a boat and outboard or quad bike, then take the next trip without these additions, using the same coil springs will be an uncomfortable ride.At Kimberley we have 4 different grades of coil springs for models across the range. Each grade is painted a different colour. Some are interchangeable with different strap lengths.The lesson we learned in the first release of the Karavan was finding the right balance between “soft” and the customers load. The secret is increasing the coil travel length in high load applica-tions. Why is this key? To take a high load, longer softer springs just compress more.Although this will change the travel height, the softer coils maintain a low spring rate which is a big advantage in ride comfort and control.We design for 170mm travel in the Karavan and Eco-suite. A little less in the Kamper and Kruiser.

Coil Springs



We are not aware of a coil spring that has “broken” but we have seen a few that have “drooped” over the years (8-10 years!) be-cause of a high load on these softer springs.Coil springs are easy to replace and inexpensive.However, in on-road travel, soft coil springs alone can introduce sway to a trailer. For camper trailers, increasing the ball weight compensates for this. So having ALL the load capacity between the axle and the hitch means that as customers load their trailer, the increase in ball weight will off set any stability issues from softer springs.For high load applications with boats and bikes, heavier coil springs are used.Rear mounted wheels, bicycles and other heavy point loads are in advisable on trailers with soft long travel coil springs.For off-road caravans, there is the option of adding an anti-sway bar. These are fitted to the independent suspension in a similar way to a vehicle. They can be easily disconnected for off-road use. These are NOT the same as the weight distribution hitches at the front of the trailer. The anti sway bars are hidden up underneath between the suspension and the chassis. There is a choice of 2 sizes.With some 4WD vehicles, particularly if their suspension has been changed, you may need the heavier anti-sway bar fitted with the softer coils that are on the Kimberley Karavan.In a nutshell, coil suspension on an off-road caravan is designed:• To be as soft as possible to maximize available vertical wheel

travel and articulation• To have long travel length to take the load on the off-road cara-

van or camper trailer. And if it is an off-road caravan

• To work with anti-sway bars added to the independent suspen-sion for highway travel at speed.

Not unimportantly, soft coil suspensions also tread lightly and result in less environmental impact.

Coil Springs and Stability



This table is the coil suspension setup in the Kimberley Range:Type

Trailing Arms Reverse swing with sleeve bushes, dual lubrication. Stub Axle position can match vehicle wheel tracking width. Toe in and Toe out Alignment 5 Year Warranty transferable to next owner.

Coil Springs Cold rolled Australian made, Anti spin tab on lower offset cup. Lower cup angled for approx 90 degree in mid point

Bump Stops Kimberley design with tapered cone, Hi impact polyure-thane. Insert bolt. Easily replaceable

Shock Absorber Twin Tube or Mono-tube, 50-50 setting, dust protector. Mo-no-tube can be rebuilt.

Bushings All stainless steel spherical busings on mono-tube. Polyure-thane busings on twin tube.

Over extension Webbing Strap, Quad sewn, tested with bushingsHubs For Disc Brakes: 2 piece with 12mm thick discs, matching

stud pattern to most vehicles.For Drum Brakes:1 piece and selected stud patterns.

Brakes Choice of Electronic Disc or Electric Drum

Coil Springs



Firstly, Air-Springs have some negatives:• They cost more than steel coil springs• They are less reliable that steel coil springs• Reduced roll stabilityBut some huge positives:• A soft “magic carpet” ride on all trailers, and• Increased stability and safety on tandem caravans as the height

can be leveled to match the vehicle regardless of the load.If your caravan has air-suspension, you can drive faster and more confidently on typical rough roads or corrugations, where higher sprung caravans may be reduced to a kangaroo-hopping crawl.There are concerns of gibber and stone damage to air-bags, howev-er, you can change out an airbag in less time than a coil spring. The price of a spare air-bag from Kimberley is less than $300. So you have the peace of mind of having a spare available. In the photo on the right, we have the air-bag deflated so you can see the length of the travel in this Kimberley Karavan. The bump stops are installed exter-nally for maximum “thump” protection.

Air-Springs (or Air-bags)



So is the higher price of air suspension and the replacement cost of air-bags worth it? Obviously, as witnessed in nearly all premium 4WD’s, the air sus-pension system conveys many benefits over an ordinary fixed coil or leaf suspension. • Increased ride control in varying conditions• The availability of an instant “lift” for off-road operation, • The ability to change height to match the load• The progressive nature of air-springs reduces the chance of “bot-

toming out” when hitting a bump too fast.• The ability to lower either side when in camp to level the trailer or

caravan• When lowered from standard height to highway or low profile

mode, the aerodynamics are improved and there is increased fuel efficiency.

For the Kimberley Kruiser, we found the fuel economy difference between “normal” height and “low travel” height resulted in 0.96 Li-tres/100klm less fuel consumption. So on a 20,000 klm trip, that is 180 litres of fuel which is about $320 saving.

However, if you are going to consider air-suspension, then consider the new Premium air-springs from Kimberley. These are a step up from the normal air-bags and offer significant advantages:

Air-Springs



There are 2 major types of air-springs available for tow-able trailers and caravans.• Fixed Diameter piston operated air-bag

(Standard)• Variable Diameter piston operated air-

bag (Premium)The Variable Diameter (Premium) one costs more yet has improved benefits. To explain how an air-spring works, we will concentrate on how the variable diameter unit operates and what the difference is.If you look at the factory supplied air-sus-pension in a Land Rover or Range Rover, the air-spring piston widens towards the top. Photo on right is au-thor’s 2012 Model TDV8 Range Rover air-spring. The white lines highlight the piston profile. The Wheel has dropped as the photo was taken on a hoist (just for this article)The wider diameter of the piston at the top effectively stiffens the suspension with a higher spring rate as vehicle height increases. The piston also widens slightly at the bottom but not progressively.This gives a harder ride off-road and a softer one at highway speeds unless the airbag is right at the bottom of it’s travel.This is an example of a difference in the suspension of a trailer or off-road caravan. In our opinion, the Range Rover setup is the oppo-site of what is needed for the trailer or caravan! On the new Kimberley Premium air-spring, the air-spring piston design has sensibly been modified to reverse this situation, giving softer spring rates in high profile and stiffer rates in low. This makes a lot more sense to us and lets explain why:

Premium Air-springs



The Premium Air-Spring is a totally new design with a two-stage pis-ton that widens out to a bigger diameter at the bottom.• It has only 3 components instead or 4• The piston is widened at the bottom for increased spring-rate• The “effective travel length” is longer as there are fewer compo-

nents. (photo below does not show the full travel on lower mount as we slid the air-bag over the bottom section too far also hiding the length of the piston)

• The upper and lower mounts are CNC machined from 6061 Alu-minum and polished where the air-bag rolls over. (far superior for wear compared to polyurethane in standard air-bags)

(The photo below shows a “mock up” during manufacture before the clamp ring is placed. The author slid the air-bag too far down the lower piston in this photo to get a comparable length as the standard air-bag for measurement purposes)

Premium Air-springs



Premium Air-springs

How does this shape change work? The air “bellows” rolls over the lower piston. With a variable diameter piston design, the bellows folds over the larger diameter section of the piston when in low profile (highway) mode. However, it reduces to the longer narrower diameter for most of its length. See the circled larger diameter in the photo above.The smaller diameter piston cross-section displaces less air for a given amount of travel, giving a softer spring rate. Conversely, when the bellows have rolled lower and are operating on a larger piston cross-section, a bump in the road produces a larger displacement of air, effectively increasing the spring rate or stiffness.This means that when the suspension sits at “standard” or “high” travel height, the spring rate is less giving more travel. This is great for low speed and off-road conditions. Finally, the resultant air-suspension has a longer effective active pis-ton which provides 40-50mm more travel at a lower rate.The result is a noticeably smoother ride when the suspension is set to “normal” or “high” with noticeably more control in highway travel at “low” mode, and more usable wheel travel.The secret of the new Kimberley Premium air-springs lies in the custom-made lower piston which is CNC machined out of a solid aluminum billet, specially shaped to vary the spring rates according to conditions. For example, the narrower top zone reduces the spring rate in high mode, greatly softening the ride. In standard mode, the bellows will touch on the widening diameter at times and yield what we regard as a “normal” rate. The fatter bottom section gives a spring rate of 150% times normal in low or highway mode.



Another feature built into the new Premium Air-spring is significantly longer travel -- with 170mm extension achieved via the longer piston and special bellows. However, we have designed the new variable air-spring to be interchangeable with the standard air-spring so that spares and even third party “off the shelf” air-bags can be purchased and used if required.In a nutshell the design features of an air-spring are:• Long travel is still preferred like the coil spring• Operate in a range of 3:1 on pressure only• Standard air-springs use polyethylene blocks with nut-serts for

securing• Premium air-springs will be precision CNC-machined from 6061-

T6 aluminum.• Premium air-springs will have at least a 1.3:1 spring rate increase

from increased diameter

Photo above is the actual CNC machine upper mount of the Kimber-ley Premium Air-Spring. It shows the dual upper mounts and air-line.

Premium Air-springs - Release Date January 2014



Air suspension is not just a matter of putting air-bags under indepen-dent trailing arms and the job is done! A caravan loses its ability to resist rollover when the tires on one side lift off the ground. Chassis flexibility, the suspension design, tire and axle deflections are all factors that need to be considered when determining a cara-van’s roll stability. Roll stability can largely be determined by the height of the center of mass of the trailer, the axle track and the softness of the suspen-sion. For example:• Changing the caravan’s axle track from 1800mm to 1950mm can

improve its roll stability by nearly 10 percent. • Reducing the height of the caravan’s center of mass by 150mm

by lowering the air-springs can also improve roll stability by a sim-ilar amount.

• Increasing the air-spring pressure by 50% will also increase sta-bility.

However, lowering the centre of gravity and therefore the air-springs both reduces the height AND reduces the pressure. These fight each other on stability. Without a way to compensate for this, the reduced air pressure in the suspension will allow more “rolling” by the cara-van, particularly at speed when cornering. The lowest pressure we use is 18-20 PSI.For this reason, the suspension design needs to have an anti-sway bar as standard for off-road caravans with air-springs but it is not needed for the very low centre of gravity camper trailers.Field testing resulted in 3 different anti-sway bars from 16mm to 20mm diameter. Generally, the lightest bar that gives the required stability should be used.We would not ship a 2.5 tonne + off-road caravan with air suspen-sion without an anti-sway bar. Should the air-bag pressure reduce because of a lower user setting or a leak, a resultant roll would be a major safety issue!

Roll Stability and overall Design



The commercial trailer industry measures ride quality by the degree of isolation the suspension provides the vehicle from road inputs without compromising vehicle control. Minimizing road forces and vibration results in less discomfort and lower vehicle and trailer maintenance cost.What factors control ride quality?Major influences on trailer protection include the suspension’s natu-ral frequency and travel. In general, suspensions with lower natural frequencies reduce the forces transmitted to the trailer and improve ride.Natural frequency comprise the spring rate of the suspension and the amount of un-sprung weight the suspension is supporting. Air suspensions are capable of achieving very low natural frequen-cies and providing very high levels of protection. • Typically, air-suspension natural frequencies are below 1.5 Hz. • Typically, mechanical suspensions have natural frequencies that

range from 2 to 5 Hz, depending on payload. The second factor in this equation is the un-sprung weight. Think of this as how a wheel controls the trade-off between a wheel’s “bump-following” ability and its vibration isolation. Bumps in the road cause tire compression — which induces a force on the un-sprung weight. The un-sprung weight then responds to this force with movement of its own. The amount of movement, for short bumps, is inversely proportional to the weight. A lighter “wheel/hub/brake/tyre set” which readily moves in response to road bumps will have more constant grip when tracking over an imperfect road. For this reason, lighter “wheel/hub/brake/tyre sets” have a lower res-onant frequency and give better road holding.

Ride Quality and Lowest Unsprung weight



In contrast, a heavier “wheel/hub/brake/tyre set” (which moves less) will not absorb as much vibration. The irregularities of the road sur-face will then transfer to the caravan through the geometry of the suspension and hence ride quality is deteriorated. For longer bumps that the wheels follow, greater un-sprung mass causes more energy to be absorbed by the wheel/hub/brake/tyre sets and makes the ride worse.So good suspension design requires:• lowest spring resonant frequency which is achieved with air-

springs• lowest “unsprung weight” which is achieved with disc brakes and

air-springs. This combination is typically half the weight of the equivalent drum brake, coil spring combination.

The shock absorbers dampen the spring (coil or air) motion but also must be less stiff than would optimally dampen the wheel bounce. The wheels vibrate after each bump before coming to rest. These motions form the “road corrugations” which we hate. It is the sus-tained wheel bounce in subsequent vehicles that enlarges the corru-gations and deteriorates the road!High un-sprung weight also exacerbates wheel control issues under hard acceleration or braking. Vertical forces exerted by acceleration or hard braking combined with high un-sprung mass can lead to se-vere wheel hop, compromising traction and steering control.

Ride Quality and Lowest Unsprung weight



So how has Kimberley perfected such a low un-sprung mass on the “suspension/ wheel set” over the last 10 years?The first item to focus on is the wheel hub and brake assembly. The disc/brake hub we use and the PBR disc brakes are half the weight of the 12inch Electric drum alternative. Then we use lower weight Mono-tube alloy shock absorbers, and the lightest weight performance air-springs or coil springs.The bump stops and suspension straps and are our own design at the lowest possible weight. The shock absorbers are mounted in the optimum perpendicular po-sition and the mono-tube shocks use stainless steel bushes for resil-ience in corrugations. (If you see dual shock absorbers at an oblique angle; the units aren’t as effective in this position so 2 are used with the result of higher un-sprung mass).Finally, the high tensile steel trailing arms have a unique curve pat-tern for the best weight/performance.The benefit to customers is not only better vehicle control and better ride but a 5 year warranty on the chassis and the trailing arms. They are well looked after in a Kimberley!

Lowest unsprung mass of any suspension



Pressure based ride height control (P)*

Pressure passes to the air-springs through individual wheel control valves as well as pressure control valves (Pad-dle Valves) that are set as drivers side and passengers side. Back up manual air control is installed (see valve fillers in photo below). Gauge is co-loured needle on dial and twin needles show pressure on each side.

Single Axle Tandem AxleSimple no-frills individual wheel air-bag pressure set-ting from air line and vehicle based compressor(No automatic control fitted ) * check inclusions.

YesManual Difficult

Individual Wheel height control from control panel P,H P,H

Manual over-ride control of air-bag pressure (and height control) should central control fail P,H P,H

Driver’s side or Passenger’s side control of ride height with specific pressure on each side P P

Ride height control of each wheel automatically moves to one of 3 pre-set heights based on vehicle. This is calibrated to your vehicle.

H H

Ride height control automatically sets level between front and rear wheels in tandem axle. n/a H

Remote control of Ride height by hand held controller H H

Drive on 3 wheels in emergency? P,H P,H

Change wheel without jack? (Road conditions and general safety permitting) P,H P,H

Drop to ultra-low level to reduce height for garage M,P,H M,P,H

Air Suspension Control Systems

Height based ride height control (H)

Pressure passes to the air-springs through individu-al wheel control valves as well as pressure control valves. Each wheel’s pressure control valve is connected to a ride height connecting le-ver on each individual independent suspen-sion arm. 3 touch buttons set the ride height which can be calibrated to your vehicle’s ride heights. Gauge is digital.



Ride Height controlled Air Suspension Systems

There is a good story on automatic ride height control with air-springs. The system can be used for either single or tandem axles but it really has big advantages with tandem axle off-road caravans.One of the major impacts on towing stability in a tandem off-road caravan is keeping it perfectly level to match the vehicle towing height… in all conditions. To understand this in full, read our eBook on towing stability.However, changing the travel height has to match the vehicle height. With the standard pressure based system, this is tedious to get ex-actly right.The ride height automatic controller will allow you to set the height and have it calibrated to exactly match the vehicle. Then it doesn’t matter how much water is on board or other loads, the air suspen-sion will go exactly to that height.We ship systems with low, normal and high height settings and cali-brate the low to the vehicle in highway mode, the normal to off-road mode and the high for when maneuvering slowly over rocks or re-versing around a ditch. It is also great for water crossings.What happens is there are “ride height” levers on each independent suspension arm and the pressure required per air-spring to be per-fectly “level” is maintained.When in camp, you over-ride the pre-selections and manually ad-just each wheel height to get the caravan perfectly level. Then when about to get back on the road, a single touch will set the ride height again. If you change the tow vehicle, you will need to re-calibrate the settings. This takes 10-15 mins.



The video direct link is: http://youtu.be/oX6rPOSWOgEor click on the image below:

Video of Digital Auto-ride height control of air suspension

http://youtu.be/oX6rPOSWOgE

http://youtu.be/oX6rPOSWOgE



Getting a flat tyre, changing a spare wheel in a tandem off-road caravanThere is nothing more frustrating that a flat tyre. Even more worrying is when you are on a narrow road with Road Trains. If you keep driving, the wheel as well as the tyre can be severely damaged.Convenience is available though with the Kimberley Kruiser which has close-coupled independent air suspension.This means that one of the suspension arms can be kept “up” while you either drive on 3 wheels or simply change the wheel/tyre without the need of a jack. How is this done?It cant be done with any “walking beam” or “Simplicity” suspension, well not very easily, if at all. The 4 independent suspension arms on the Kimberley off-road caravan have independent air suspension at each suspension arm. Individual valves allow you to drop all 4 arms down to the “bump stops” and then raise only 3 of them leaving the 4th one “up in the air”.To test this, we demonstrated the exact process to a customer who wanted the facility of changing wheels/tyres without the need of a jack for the off-road caravan.

Changing a Wheel /Tyre without a Jack



There may be situations where you can’t change a wheel easily however, like a creek bed or difficult terrain.In those circumstances you should be able to drive off on only 3 wheels with one raised and then change at a convenient time.To test this, we drove from Coffs Harbour to Penrith on only 3 wheels with a Black Caviar model off-road caravan. The result was great. The Kruiser is designed so that half the maximum axle load can be taken by one wheel and one tyre.What happens if I stake an air suspension chamber?You can drive on 3 wheels to somewhere safe and convenient. Or you can carry a spare with you.

Driving on 3 wheels in an emergency

Anti-Sway Bars

This photo shows the anti-sway bars fitted up into the top of the indepen-dent suspension with linkages on either side.

2 different sizes are available.

The discussion on anti-sway bars is in the previous chapters.

At Kimberley, we warrant the chassis and suspension arms for 5 years, that is how confident we are with our product. We have over 6,000 chassies rolling around in remote places and have an excellent reputation for durability and product quality.

5 Year Warranty



An Interesting Air-Suspension set up by an Individual

This is an interesting air-suspension setup obtained from an individual’s photo on the net. (for privacy no link available)

Great to see someone trying to get into air-suspension, but...

The educational question is what is vulnerable in this setup?

• Assume bump stop is inside airbag, what is effective travel?• Upper airbag mount not clear but looks lateral, not overhead.• No chassis support directly above air-bag top mount• Shock absorber at a strange angle, and at this angle 2 may be needed.• Shock absorber mounts are at 90 degree to each other• Tube size on suspension arm looks under-sized• Open tube end on suspension arm

guide to best suspension design for off road caravan

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