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The Wheel

The wheel is perhaps man’s greatest invention. Simple as it seems, it is the very basis of movement. The cart, the cycle, the motor-car and the railway train move on wheels. Even aircraft which fly thousands of kilometres through the air need wheels for taking-off and landing. It is not only for transport that the wheel is vital. Machines that produce various goods for us, watches that tell us the time, generators that produce electricity, and many gadgets which have become essential in our day-to-day life cannot work without a wheel.

The Wheel

The Wheel [Illustrations by: Ahmed]

One would, therefore, think that the inventor of the wheel must have earned great fame and fortune. But as a matter of fact, no one even knows who the inventor was. You can imagine how difficult it must have been for man to move about or carry heavy loads without a wheeled vehicle. It was only 5000 years ago (about 3000 B.C.) that some ingenious person invented this simple device which has become the most important and the most universal tool of man today.

The wheel did not immediately put an end to the use of beasts of burden for carrying loads. In fact, in some countries of Asia and Africa not only animals but men also are used to carry goods and passengers even today. Even in technically advanced countries, men and beasts are still used at places where machines with wheels cannot reach, for instance, on snow-bound mountains and in dense forests.

Before the invention of the wheel, it must have very difficult to travel long distances. Travellers carried their belongings on their backs and faced many hazards on the way. There were no hotels or serais on the route where they could take shelter or rest and eat. Very few, therefore, dared to travel. Even those who undertook a journey did not know when they would reach their destination and whether they would return home safely.

How did the wheel come into existence? Let us go back to man’s early history. Man first began to tame animals for his use. The first animal to be tamed was the dog. It kept watch and warned its master of approaching danger. The dog was also used in hunting.

Man soon discovered that a pack of dogs could pull a fairly heavy load. He made a frame of sticks, placed loads on it and made dogs pull it. This vehicle was called a sledge. Sometimes the man himself sat on the sledge and had a ride. In Northern Europe, sledges made of raw hide, bark or hollowed tree-trunks were used long before the invention of the wheel. In Egypt and Syria sledges were used for shifting huge stone statues even after the wheel was adopted for chariots and wagons.

Later animals other than dogs were also tamed and trained. They were used either for riding or for carrying goods. Thus, donkeys, mules, horses, camels, elephants, oxen and other animals were employed. This helped traders and pilgrims to move about and mix with one another more frequently, through they faced many hardships and dangers on the way.

As we have said, the sledge was man’s first vehicle. By providing it with wheels to roll forward, man took an important step in the history of transportation. Rolling motion is far better than sliding motion because it reduces friction considerably.

All the time man was looking for some means of carrying himself and his goods over longer distances with greater speed, comfort and safety. It is possible that he discovered that by putting a few round sticks under a sledge it was easier to make it move. You must have seen that this method is used even now when heavy loads have to be moved in offices and factories. The load is mounted on one or two round pipes and made to slide over them. When the load moves forward, it leaves behind the pipes, which are picked up and again placed in front under the load and thus it kept moving.

The Wheel

The Wheel [Illustrations by: Ahmed]

Early man must have used round sticks cut from the branches of trees to slide loads over, long before the wheel was invented. But this method can be used only for moving loads over short distances. Moreover, it is a slow, time-consuming process.

Then some imaginative person must have got the idea of making a wheel. He had nothing known to adapt or copy the wheel from. The first wheel is supposed to have been devised in the East, probably in Mesopotamia. Excavations carried out in Mohenjodaro show that ox-carts with two large, solid wooded wheels were in use 4000 years ago. The first wheels were made of three planks of wood held together by wooden struts, and were nearly round in shape.

Thus the wheel came into existence. Later, the inventor of the wheel must have cut two round discs from the thick trunk of a tree, made holes through their centres and fitted them to either end of a strong rod forming an axle, so that they could turn round freely about it. Man must have found that moving loads with the help of wheels was much easier than by using rollers.

It was soon discovered that the larger a wheel the smaller was the effort required to draw the load. It was possible to get logs only of a certain thickness. If larger wheels were needed, they had to be made by putting pieces or sections of planks together. These pieces had to be joined together firmly and trimmed to a round shape.

The discovery of metals helped greatly in making bigger and better wheels. A strip of metal placed around the outer circumference of the wheel formed a tyre which held the pieces firmly together and gave a smoother running surface. Besides the metal tyre could stand wear and tear better than wood. Thus, the usefulness and life of the wheel were greatly increased.

At first, wheels must have been used in wheel-barrows or carts which had single axles and just one pair of wheels. Later two or more pairs of wheels were attached to a strong frame and larger carts and wagons came into use. These carried heavier loads and were pulled by teams of animals.

Although now horses were harnessed to wheeled vehicles, thereby increasing the speed of travel, the wheel itself showed little progress during the next 1600 years. This period is called the ‘dark age of the wheel’.

The spoked wheel came much later. As wheels grew larger, they became heavier too. Their weight added to the load that had to be moved. Something had to be done to make the large wheels lighter. With a metal band to hold the pieces together, it was no longer necessary to have a solid wheel; some of the wood could be cut out. What was required primarily was the central hub through which the axle-ends passed. Then there had to be the rim over which the metal tyre was fixed. The wood in between only served to hold these two parts together. A few strips of wood could do this just as well; the rest of the wood could be removed. These strips of wood were called spokes, and they made the wheel much lighter.

As heavier carts and wagons came into use, another difficulty arose. Their wheels sank deep into the earth, especially after rain, when the ground was wet. It was difficult pulling a heavy load on such a surface. Some sort of hard surface for the wheels became necessary, and this led to the building of roads. Important roads and streets began to be paved with bricks or stone slabs. Later roads were made by spreading broken pieces of stone and levelling them with a heavy roller to give a smooth hard surface. Such surfaces could take heavy traffic, and they also put the idea of speed into people’s heads.

On poor roads man was content to jog along at the walking-pace of an animal. If he was in a hurry, he rode a horse and could move as fast as a horse could gallop. But neither horse nor man could hold this pace for long, as they were both soon tired. Bumping their way over rough roads, the large wooden wheels transmitted every jolt to the passenger. Comfort was out of the question.

Roads improved, and light carriages began to be made and used. Rich people rode in them at a fast pace. Some attempts were made to introduce a little comfort, such as suspension of the coach-body on leather straps, but they did not do much to cushion the bumps. This kind of suspension was the fore-runner of metal springs which helped to reduce the shocks caused while moving fast over rough patches.

By the middle of the seventeenth century A.D., better roads were laid in Britain and people travelled as much as 30 miles a day in horse-drawn carriages. Relays of horses were kept or could be hired at suitable points along the route. Tired horses were changed at these places for another spurt of fast driving.

Better roads made greater speed possible and demanded better wheels which revolved faster and more smoothly. It had thus become a race between the road and the wheel. The invention of the steam-engine and the motor car brought in invention of the steam engine and the motor-car brought in faster modes of transport. Steam-power was first used on roads, but it was soon realised that it could be put to better use on rails. Motor-cars moved at a speed not dreamt of in the days of horse-drawn carriages. Roads had to be vastly improved to cope with these speeds by paving their surfaces with cement, concrete or bitumen.

Wheels had to keep pace with this progress. Towards the last decade of the nineteenth century, the wheels of motor vehicles were fitted with solid rubber tyres. Yet road transport remained a slow and uncomfortable experience. Then came a major breakthrough in the history of transportation. In 1888, John Boyd Dunlop, a British veterinary surgeon, invented the air-filled pneumatic tyre. This tyre enabled the wheel to prove its true value as a remarkable invention. The air in the tyre acted like a cushion and absorbed shocks. For extra comfort soft, over-sized tyres, called balloon tyres, came into use. Wheels were made entirely of metal and thin spokes were used to make them as light as possible.

The principle on which the first Dunlop tyre was based was the same as the one which makes our motor-cars or bicycle run so smoothly at the high speeds of today. Wheels of bicycles or motor-cars actually run on compressed air. The inner tube of the wheel is made of soft, thin rubber. The outer tube that fits over the inner tube is thick and tough to protect the inner tube from injury. It is the inner tube, filled with air, which has been the cause of the breakthrough to greater speeds and comfort.

At high speeds, the rubbing of the axle-ends against the surface of the hubs generated heat and resulted in a great deal of wear. To avoid this, special types of bearings called ball-bearings were fitted. As the wheels moved, these balls rolled and reduced much of the wear and tear.

Wheels are also used in trams and trains, which are so heavy that ordinary roads break up under their weight. Their wheels, therefore, move on special tracks made of steel rails.

John Dunlop’s invention has spread to all parts of the world. These wonderful tyres are used on cycles, motor-cars and aeroplanes. They are used on lorries which carry heavy loads of several tons and on aeroplanes which race along the ground at tremendous speeds as they take-off and land.

One of the greatest and certainly the most basic invention of all time in the means of transport has been the wheel. No other single invention has so greatly helped man conquer distance. This invention set the pattern of land transport for 50 centuries. Places which in olden days seemed far away now appear to be just round the corner. Journeys which took months and even years at one time now take only days. From the days of animal-drawn vehicles before 3000 B.C. it was a slow journey to steam-power in the eighteenth century. Mankind owes a lot to the unknown genius who invented the wheel.

First published by National Book Trust, India

Category: Features for Kids