For more than 100 years, vehicles have been rolling along on cushions of air encased in rubber. Sometimes, we get so used to a certain product that no true changes are ever really made for years, decades even. So begins an article discussing the development of airless tyres, something that has become more prevalent in the past few years. A few tyre companies have started experimenting with designs for non-pneumatic tyres including Michelin and Bridgestone, but neither design has made it to mass production.
Creating a new non-pneumatic design for tyres has more positive implications than one might think. For one thing, there are huge safety benefits. Having an airless tyre means there is no possibility of a blowout, which, in turn, means the number of highway accidents will but cut significantly. Even for situations such as Humvees in the military, utilizing non-pneumatic tyres has a great positive impact on safety. Tyres are the weak point in military vehicles and are often targeted with explosives. If these vehicles used airless tyres, this would no longer be a concern.
There is also an environmental benefit to using this type of tyre. Since they never go flat and can be retreaded, airless tyres will not have to be thrown away and replaced nearly as often as pneumatic tyres. This will cut down landfill mass significantly.
Because of the benefits, I believe that it is extremely important that research and production of airless tyres is continued and increased. This type of innovation works well in conjunction with several engineering codes of ethics, and thus should be embraced by engineers everywhere. Cars are things that people use every day, so any improvements over existing designs would affect the lives of the majority of people. Learning about such a topic, therefore, I believe holds extreme value- especially for us freshmen engineering students. In doing research into these kinds of topics that hold significant meaning, we can see that what we will do can make a difference.
Going back in history, initially a craftsman known as wheelwright forged bands of iron & steel, tying the wheel segments together as the metal contracted around the wheel. Hence the name, tyre, as it tied the wheel together. This was then placed on wooden wheels of carts and wagons.
Explorers had seen Indians using sheets of rubber for waterproofing and in the 1800’s, Charles Mcintosh was experimenting with this latex – sap from a tree in the Amazon. It had its problems as the cold weather caused it to be brittle whilst in hot weather they became sticky. However, in 1839, Charles Goodyear discovered that by adding sulphur to the melted latex it gave elasticity and strength. This vulcanized rubber was used to as cushion tyres for cycles.
John Dunlop, trying to make his son’s bicycle more comfortable to ride on, managed to invent the pneumatic tyre. Another person, Robert Thomson, had already patented the idea of a pneumatic rubber tyre so the Dunlop Rubber Company was established and won a legal battle with Thomson. In 1891, the detachable pneumatic tyre was invented by two brothers, Micheline, consisting of a tube bolted on to the rim.
In 1948, Michelin revealed the first radial tyre was developed and this was a revolutionary achievement as it used steel-belted radial tyres. The advantages meant longer life and increased mileage for the vehicle. However, it required a different suspension system and so was slowly adopted. This was the tyre along with Dunlop’s invention, which gives us the tyre we have today.
We have seen heavy tyre development, especially in motorsport, however we are yet to see anything as revolutionary as previous key points in history. There have been concepts, with a major one being the Michelin Tweel announced in 2005.
Before the technology of airless tyres is discussed, it is important for the reader to understand how standard pneumatic tyres function, and what advantages and disadvantages there are to using them. A brief overview of the general concepts of airless tyres will then follow.
The basic design of all pneumatic tyres is very similar, even though there are many different types. They all include an inner core that holds pressurized air which is then covered with a layer of rubber that comes in contact with the road, called a tread. The tread helps keep traction with the road and prevents slipping and skidding. The tread has the tendency to wear down over time, so if the tyre has not gone flat, a person will usually replace it at this point.
A main reason for using pneumatic tyres is the deformation that occurs during rotation. As the tyre rolls, the weight of the car pushing down on it causes the tyre to flatten slightly. This, in turn, causes the tyre to have a larger surface area to be in contact with the ground, which makes for better traction. It also gives a slight cushioning effect, making running over small rocks or debris unnoticeable. Or, as writer for How Stuff Works Ed Grabianowski puts it.If you’ve ever taken a ride in an old-fashioned carriage with wooden wheels, you know what a difference a pneumatic tyre makes.
Pneumatic tyres have their advantages, but they also have their disadvantages as well. The possibility of a blowout or flat (when air is let out suddenly from the tyre) is a major concern because they have the tendency to cause severe accidents. The task of regulating tyre pressure is also a disadvantage because consumers are usually not very good at it. Although it may help with traction to have the tyres a little flat, it comes at the price of handling. When there is not enough air pressure in the tyre, the sidewalls flex causing the tyre to not quite follow the desired line of steering. It is because of these disadvantages that tyre companies have taken an interest in designing airless tyres.
ADVANTAGES AND DISADVANTAGES OF AIRLESS TYRES
4.1 Advantages of airless tyres
1. Eliminates air leaks or tyre blow outs.
2. With no air pressure you are left with consistent economy and handling.
3. Its flexibility provides an increase in surface area of contact.
4. No maintenance needed.
5. To lengthen tread life.
6. Facilitate recycling.
7. Makes Vehicle more Efficient have high lateral strength for better handling without a loss in comfort.
8. Vehicle remains under control even in emergency brake.
9. Remains mobile even with some of the spokes damaged or missing.
10. Durability & Long Life.
11. Can take gunfire or explosion.
11. Less environmental impact.
4.2 Disadvantages of airless tyres
1. Lack of adjustability
One of the biggest disadvantages of the Tweel is that once it has been manufactured, it cannot be adjusted. In this case if the car needed a different kind of setting, a whole new set of Tweels will be required. On the plus side Tweels are made with five times the lateral stiffness compared to pneumatic tyres, enabling very responsive handling.
2. Not as economic as pneumatic tyres
Michelin are currently working on enabling the Tweels to be as fuel efficient as pneumatic tyres. Currently they are within 5% of the rolling resistance and mass levels.
This could be one of the Tweels biggest downsides. Vibrations become considerate once a vehicle is driving above 50 mph, while causing a lot of noise. Also disturbing is the amount of heat the Tweels generate. Long distance journey with tweels would be very unpleasant unless these areas are improved upon.
4. Different Manufacturing process
Another problem is that creating airless tyres requires a totally different manufacturing process. At this point of time, the tyre industry revolves around the manufacture of traditional pneumatic tyres. To modify factories and service equipment would be a major change, and the facilities just don’t exist yet.
Tyres may seem to be a trivial part of an automobile that cannot be improved, but research into airless tyres shows otherwise. This new technology will increase the safety of cars as well as have a positive impact environmentally. Since these tyres are also able to be retreaded, there is the possibility of a smaller cost per tyre- which is always embraced by the consumer. This innovative project is also backed and guided by engineering codes of ethics which will ensure that the development is conducted in a way that it responsible and fair.
It is also important to think about the implications of a technology such as this. This is reinventing the wheel in a way! If engineers can do this, they will think about other things that can be improved. Then we will not only have inventors of entyrely new technologies, but also people who can take something already in place and make it even better. This type of innovation will become increasingly valuable in the future which is why researching topics such as this is very important for young people. It gives them a sense of what they can do after all of their hard-working years of schooling and that what they can do will matter.
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