Automotive

Fascinating Air Suspension Wheels bring new thinking to one of man's oldest problems

Fascinating Air Suspension Whe...
Wheelchair users would likely experience more ride comfort, as well as a vastly superior ability to negotiate uneven ground riding on Air Suspension Wheels
Wheelchair users would likely experience more ride comfort, as well as a vastly superior ability to negotiate uneven ground riding on Air Suspension Wheels
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Air Suspension Wheels: design for a mountain bike hub
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Air Suspension Wheels: design for a mountain bike hub
Air Suspension Wheels: design for a bulletproof military vehicle wheel
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Air Suspension Wheels: design for a bulletproof military vehicle wheel
The monstrous 25-foot-tall Caterpillar 797F mining truck with its 13-foot-tall standard pneumatic tires
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The monstrous 25-foot-tall Caterpillar 797F mining truck with its 13-foot-tall standard pneumatic tires
Wheelchair users would likely experience more ride comfort, as well as a vastly superior ability to negotiate uneven ground riding on Air Suspension Wheels
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Wheelchair users would likely experience more ride comfort, as well as a vastly superior ability to negotiate uneven ground riding on Air Suspension Wheels
Air Suspension Wheels: installed on a piece of industrial machinery
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Air Suspension Wheels: installed on a piece of industrial machinery
Air Suspension Wheels: installed with metal tread
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Air Suspension Wheels: installed with metal tread
Air Suspension Wheels: inner workings can be covered up with hub plates
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Air Suspension Wheels: inner workings can be covered up with hub plates
Air Suspension Wheels: tread can either be fitted as sections of road-grooved rubber, or as bolt-on blocks for offroad use like this
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Air Suspension Wheels: tread can either be fitted as sections of road-grooved rubber, or as bolt-on blocks for offroad use like this
Air Suspension Wheels: component breakdown
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Air Suspension Wheels: component breakdown

We put up with a lot from our pneumatic tires, from punctures and blowouts, to slashings and the certainty of relatively frequent, inconvenient replacements and giant piles of waste rubber. The current technology seems well overdue for a revolutionary overhaul, if you'll pardon the pun, and yet despite dozens of fascinating attempts to reinvent the wheel, nothing seems to have found traction yet. Boy, I'm on a roll here.

The latest idea to come across our desks, though, makes a compelling business case for itself as well as offering some interesting dynamic capabilities. Meet the Air Suspension Wheel (ASW), from Global Air Cylinder Wheels out of Chandler, Arizona.

Air Suspension Wheels: component breakdown
Air Suspension Wheels: component breakdown

Like a regular pneumatic tire, the ASW is air-suspended, but in this case, it's not by an inflated tube. It's a full hub and wheel replacement that separates the outer tread and rim from the hub using a set of eccentrically mounted, pneumatic air cylinders.

These air shocks are tuneable to give you whatever level of tire deflection you choose, from super-firm to softer and squishier than a regular deflated tire can handle. Likewise, you can design in whatever degree of lateral flex suits your application, and even whatever level of torque flex you'd like, which allows the wheel to flex a little on the axle before it turns. This allows it to act as a soft torque coupler and gives a touch more traction in very difficult circumstances before the wheel spins, as well as slightly isolating the drive train from damaging torque forces in the rough stuff.

Air Suspension Wheels: tread can either be fitted as sections of road-grooved rubber, or as bolt-on blocks for offroad use like this
Air Suspension Wheels: tread can either be fitted as sections of road-grooved rubber, or as bolt-on blocks for offroad use like this

As far as treads go, the sky's the limit. Treads bolt directly onto the outer rim piece by piece, and there are a bunch of options to choose from, including a range of pre-molded road retread options by companies such as Michelin that bolt on in sections, or a plethora of heavy-duty industrial options that use polyurethane, urethane or steel pieces in a range of different configurations for serious off-road grab.

Large-scale mining applications – where the dollars make the most sense

The company has set its sights on large mining operations to get things moving; a market where time is money, costs can be projected across decades and gigantic, short-run tires for enormous equipment can cost tens of thousands of dollars each.

The monstrous 25-foot-tall Caterpillar 797F mining truck with its 13-foot-tall standard pneumatic tires
The monstrous 25-foot-tall Caterpillar 797F mining truck with its 13-foot-tall standard pneumatic tires

Take the mammoth Caterpillar 797F Mining Truck (pictured above), which stands more than 25 ft (7.6 m) tall and weighs in at 1,375,000 lb (623,700 kg). Each of the big Cat's six monstrous 59/80R63 tires stands over 13 ft (4 m) tall, weighs about 12,000 lb (5,440 kg) and costs somewhere in the range of US$38,000 each.

Making a bunch of assumptions about usage, you're up for a set of six of these huge hoops a year plus a spare, giving you a 10-year tire budget of around $2.66 million per truck. (These figures are adapted from the ASW company's own comparison spreadsheets, which use rubber tire pricing of $110,000 each from 2009. These tires are now much cheaper according to our research.)

A set of ASW wheels, on the other hand, will cost you more upfront but last something like 13 times longer – out to the service life of the truck itself. Your first set of six wheels in this case will run you about $1.705 million, but over 10 years you'll likely only need two tread replacements at around $55,000 a pop, giving you a 10-year budget of $1.815 million and a $845,000 saving.

Air Suspension Wheels: installed on a piece of industrial machinery
Air Suspension Wheels: installed on a piece of industrial machinery

Things turn even further in the favor of the ASW system if you factor in punctures, blowouts, tire fires and how long a truck has to be out of service each year while those monster tires get changed. ASW treads are bolt-on, bolt-off chunks that can be changed with very little gear, without even jacking any wheels up, and done in sections during shift changes and lunch breaks so the truck's never out of service due to tires. They can also ship much more cheaply, since the whole assembly can be broken down into bits that easily fit in a regular shipping container.

Not to mention, they're virtually invulnerable to sabotage, as they can't be slashed, and their inner workings are protected both from malicious acts and from mud, dust and water by big metal plate covers. So they can also be made bulletproof for military vehicles.

Air Suspension Wheels: design for a bulletproof military vehicle wheel
Air Suspension Wheels: design for a bulletproof military vehicle wheel

Smaller applications, like wheelchairs

The Global Air Cylinder Wheels team has also sent us a bunch of video detailing the advantages of a much smaller scale ASW for wheelchairs. Because of the built-in suspension effect, you'd likely experience more ride comfort, as well as a vastly superior ability to negotiate uneven ground without any of the wheels lifting off and losing stability.

The suspension effect also makes it much easier for a wheelchair user to negotiate steep curbs, both nosing down and backing up, as the suspension effect takes much of the steepness out of the exercise.

It's unclear at this point whether you'd lose any forward motion energy due to torque flex, but that can be tuned out of the system if required in any case. It's also unclear how much a pair of wheelchair-sized ASWs would cost at this point. We assume they're not cheap compared to a regular rim and tire setup. Here's some annoyingly infomercial-style video comparing regular wheelchair wheels to an ASW setup over curbs and grassy, uneven terrain.

Air Suspension Wheels

It does seem clear the Air Suspension Wheel is unlikely to take over as a car tire replacement any time soon. But its unique set of capabilities do seem to offer some compelling advantages in certain applicarions, and we look forward to seeing how things progress.

Source: Global Air Cylinder Wheels

5 comments
Bob Stuart
The wheelchair application seems to run straight into the eternal problem with sprung wheels. Without dampers, they bounce badly, as sometimes seen in tractors fitted with buckets on a bad road. With dampers, they have very high rolling resistance. I tire needs enough flex to meet the ground, but any further suspension should be on the axle.
Lardo
As a full time wheelchair user, I cast a very skeptical eye at said "annoyingly infomercial-style video". About the only places I have trouble are in soft gravel, sandy beaches, and deep snow. Certainly not gentle curbs and flat lawns. And it's not like I have some high dollar customer sport chair, either. I use a "Breezy". Street price of $575. About as cheap as you an go. (https://www.quickie-wheelchairs.com/Breezy-Wheelchairs/Breezy-Lightweight-Wheelchairs/Breezy-600-Lightweight-Wheelchair/2403p) And the only modification I made was to cut grooves into the solid rubber tires. (They come smooth as a babies butt. That REALLY doesn't work in snow.)
Grunchy
I think the wheelchair demos are rigged. You can make the original rubber tire style appear to 'fail' by simply leaning forward a bit and weighting up the front tires, and the back tires don't have enough load and they slip when climbing the curb. Similarly on the gravel, you just put your weight onto the front wheels and they dig in and won't roll. The weight shift is subtle, but it's there and it's just enough to make the wheelchair appear to 'fail'. I can solve each of these situations by balancing onto the back wheels thereby lofting the front wheels - zero advantage to the new wheels. I'm disappointed that there's no video showing how the internal shocks work, or how lateral deflection works or is tuned. Also the biggest issue with road-going wheels is known as "unsprung weight". That is to say, how heavy is the wheel & tire assembly. Nothing is mentioned, so I'm going to go ahead and assume it's disadvantageous for the mechanical solution as compared to the good old rubber tire. Granted, it makes no difference for slow speed uses such as wheelchairs or mining trucks. Ultimately - I find the whole concept is presented in a somewhat deceptive manner. That turns me off.
Reason
You realise in the mining truck example if their estimate of current tyre prices is out by a factor of nearly 3 (as you suggest 38k v 110k) then the whole financial justification falls apart ;) Punctures and other damage sure, money no ... at least not yet.
Harmen van Kamp
Great comments and I would like to explain the questions raised, because it is a huge innovation. Wheelchair: Nothing is rigged about it. Two of the cheapest identical Invacare wheelchairs were bought and one was modified with the Air Suspension Wheel technology. Zoltan (the inventor) has never been in a wheelchair before and therefore it may seem a bit clumsy, but definitely nothing was done intentionally. Here is the video of how it works in gravel: https://www.youtube.com/watch?v=A429IzLKbWM&t=2s. @ Bob Stuart: The built-in air cylinders avoid the bouncing. The very first design in 2010 was actually with springs and, indeed too bouncy. The cylinders have a non linear suspension (exponential) that have a great dampening effect. @ Reason: We will update the pricing which we took from a catalog in 2009. The price advantage is still significant, if it was only because of changing over a consumable into a capital asset that can be amortized. Besides, only the treads need to be replaced at a fraction of the cost of a rubber tire. Investment, yes, value for money, certainly. @ Grunchy: Very good question regarding the un-sprung weight. Due to the internal suspension, only about a 1/3 of the total weight of the wheel is un-sprung weight, actually lowering the weight that is 'seen' by the axle. Therefore, even IF the ASW would be heavier overall, the vehicle's drive-train sees far less strain and weight.