Wheel

A wheel is a disc- shaped object with ideally circular contour, which is mounted rotatably about its axis of symmetry and is most commonly used as a wagon wheel. His invention and use of carts or wagons was an important one for the development of technical culture in prehistoric event.

Essential advantage is the unwinding of its circumference on the ground. Sliding takes place only in the lubricated bearings. The rolling resistance on a firm, dry ground and resistance to sliding in the bearings are commonly much smaller than the sliding resistance with the use of a loop or of a carriage for transporting a load on dry ground. The abraded material is also less than in grinding. Fellow with wheels and draft animals were available for good and durable transport for loads and people in parts of the world.

During the Bronze Age, the wheel has been known today for his form of the disc - the lighter spoked - further developed. The spokes form was created by the removal of not required for the function of the wheel parts of the disk between the inner ( hub ) and outer ( rim ) area.

The simple machine elements one usually not rolling, but only the rotating wheel (for example, hand wheel, steering wheel ). A vehicle is now called the complex technical component or complex machine element.

The name wheel is cognate with the Latin rota and the Sanskrit word for the Indian car ratha.

3.1 wheels for vehicles
3.2 Vehicles with the suffix or prefix " rad"

6.1 wheelsets of rail vehicles

7.1 The wheel in machinery
7.2 The wheel for torque generation in combustion engines
7.3 Function as an energy storage

History

Long was the Sumerian culture as the origin. Today, the dating of finds or representations of chariots and wheels from Central Europe and Eastern Europe as well as from Mesopotamia to the middle of the 4th millennium BC are close together. A more detailed chronological and geographical classification of the invention is not yet possible. In pre-Columbian America and in Australia, the wheel was unknown for transport.

A little earlier or at the same time also provided with slide bearings, rapidly rotating potter's wheel was known. An indication that the machine element sliding bearing was now well controlled: lubrication and minimize play.

Mature transport equipment

The first transport device with which one could carry loads on land, without carry, were sled and rod loops. In the loop, however, a part of the load and the design weight is to wear, she had an advantage over other means of transport, a good off-road capability. With the use of carriers and grinding rod generally a high sliding resistance was overcome. A transport rollers was possible only on well prepared surface and short distances. Proved is rolling transport from the Bronze Age Egypt. The disadvantage was that the rollers all the way designed or repeatedly taken back and had to be placed in front of the object to be transported over again. But you could move relatively heavy loads, as these are spread over a larger area than it is in the bearings of the wheel later. The roller transport is also still used today for special purposes such as the relocation of buildings or extreme loads over short distances.

First evidence of the wheel

The rotatably mounted wheel, ie its "infinite " rotation about an axis, could be made with stone tools. The pottery of the Indus are regarded as the first, BC constituted the potter's wheels in the 5th millennium in ceramics production.

The first wheels were mono- or multi-part disk wheels with diameters between 40 and 80 cm, fixed, loose or without the hub sleeve or fixed axle ( axle holes and square ). The first evidence of carts, wheels, cars or their models there are from the second half of the 4th millennium BC, between North Germany and Mesopotamia, for example, in the foothills of the Alps, in the northwestern Caucasus ( Maikop culture), in Mesopotamia and in the Indus Valley Civilization ( Harappa ). Cart representations come from Bronocice ( southern Poland). Among the oldest finds are both one-and two-axle vehicles. As the oldest indirect evidence of wagon wheels in Europe is considered a lane from the 4th millennium BC in a barrow at Flintbek ( Rendsburg- Eckernförde ). Possibly the oldest wheel in the world was found in Federseemuseum Moor in Seekirch - Achwiesen. It is approximately 5,000 years old and constructed of two wooden parts. The oldest verified date wheel and axle combination comes from Gmajne Stare at Ljubljana in Slovenia, the wheel were in the 2σ region in the years 3340-3030 cal BC, dated the axis to 3360-3045 cal BC

This oldest Radfunde are either assigned to burials in graves or cars are bog finds from wetlands.

The dates of the sites currently allow no decision on a place of origin of the bike and trailer technology. A more recent attempt pleads for example, for a Central European cars invention.

Usage traces

One of the four in Glum, Oldenburg district, found one-piece wheels from the Bronze Age had a scouring furrow, which was not incorporated in the whole circle of rotation. It was created by the wagon body, which wore down the wrong current ( " eiernde " ) wheel. A shorter groove on the other hand shows that there is also attached the wheel is rotated. The edge of the tread is chamfered or rounded. Some faces were so well preserved that smoothing strokes of a tool can be seen. The wheel created from alder wood belonged to a car whose front axle could not swing. When changing the direction of travel draft animals dragged the front of the car to the side until the tiller pointed in the desired direction. In the book holes of the wheels stuck made of birch wood bushings which show by their ( soft ) material that the car was not designed for prolonged use. Transverse forces (for example, when changing direction ) caused a funnel- shaped widening of the ends. From other archaeological material is to open up so that the wheels were taken from parked cars in order to maintain the elasticity of the axes of wood.

Developments

Even in the stone age they began to reduce the high weight of the disc wheels through grooves. Whether the fluted with symbolic patterns wheels were, however, suitable for load carrying, is doubtful. A metal- temporal invention was the spoke, which was introduced around 2000 BC in the Middle East. With the stable and lightweight spoked wheel was built so-called chariot, ie two-wheel vehicles, which should actually be called carts. Since Zweirädrigkeit was a good way to reduce the weight even more demanding single axle were built later. Had the first spoked wheels bronze spokes, so they built later in the Bronze Age and then mostly wooden spoke wheels, on which only the grinding on the axle inner surface of the hub and the outer tread of the wheel with metal was shod. Metal spokes were until the 19th century, again a leader, be it due to higher loads and speeds, such as the railways, it was after the invention of the spokes fall made it possible to build very light and solid wheels with thin tensioned wire spokes, as especially when today Bicycles are common.

The wheel in the New World

In Central America, the Maya invented the wheel at temples is to be seen on stone ornaments as a spoked wheel or gear. How far is from finds, but they used it only in applications that did not allow external loads, as for the wheels to represent their calendar and for toys (example in the Berlin Ethnological Museum ). Already in pre-Columbian times they used wheels, even gears, in more or less precision equipment. Cars are but in the ancient American cultures has not been established. This is possibly due to the lack of suitable draft animals such as horses.

Materials

As the material only wood was used for thousands of years. The first spoke wheels had spokes bronze, later in the Bronze Age and then outweighed wooden spoke wheels, on which only the grinding on the axle inner surface of the hub and the outer tread of the wheel with metal was shod. Advances in metallurgy toward ever more stable metals were then also be used here. Only with the invention of the steam engine and the internal combustion engine, which enabled higher transport services and speeds, the wheels were completely in iron, later steel plate welded together run as rim. The lubricated hub sleeves were replaced by roller bearings. Wheels for low loads were provided a lightweight construction with wire spokes that are biased and loaded on train.

The design of the wheels was always ( until later paths and roads ) matched to the surface to be traversed, and improves the surface corresponding to the increased requirements. Thus arose:

Steel wheel on wooden rim for wheels of wheelbarrows, two - or four-wheeled wagons, carts or carriages on farmland, field or boardwalks or cobblestone streets or the first commercially operated electric streetcar of the FOTG in Germany on rails
Hard rubber frost on wood or cast iron ring for the first motor vehicles, longer still for the trucks on paving roads
A pneumatic tire on the rim of the road vehicle and aircraft on asphalt or concrete road.

Specific developments of the wheel for other means of transport than road vehicles are:

The railway wheel with steel tire and wheel flanges, used with cranes and escalators
The pulleys or wheels to support the endless traction cable ropeways and chairlifts and ski lifts.

Today, hard rubber tires are used on steel wheels as training wheels, for example, for tracked vehicles, for Roundabouts, for cable cars and chairlifts or industrial vehicles such as forklifts.

Plastic wheels with or without metal hub or bearings, often without rubber tires are available for mobile tables, ladders ( also above), Furniture, Pallet Trucks for Euro - pallets and shopping carts (even with webs to clawing on moving walkways ).

Most accurate wheels made of plastic are used in precision engineering for power transmission as well as to switch.

Wheel and Axle System

The wheel and axle system is primarily used for transport; the one on vehicles, on the other hand as a force deflection of hoists. Axes are used for carrying loads and are therefore claimed mainly to bending; Shafts transmit torque and (torsion) are therefore mainly exposed to torque.

Wheels for cars

Will wheels by means of bearings rotating on axes - today mostly on journals - mounted a vehicle, a substantial reduction of the friction forces and thus energy is thus compared to the loops of the transportable object over a distance to be traveled or saving transport of heavy goods. rapid movement of goods and people, primarily on relatively flat routes, achieved.

For comparison: In order to grind a steel plate of 100 kg mass over a distance of 10 m or to drive, the following work is in each case (corresponding to force times distance ) terminated: The friction force respectively occurring resulting from the normal force ( corresponding to the mass times the acceleration of gravity ) multiplied by the coefficient of friction. The coefficient of friction for a combination of steel on rough surface is 0.5, which for steel on steel (smooth) 0.1. When grinding the friction force the whole 10 m distance seems far on rough ground, thus the work Ws to results

When driving with wheels of diameter 1000 mm and axle diameter 50 mm reduces the path of the steel hub, which rubs against the steel axle, the ratio of the diameter and thus the work Wf yields to

( dimension for viewing: a Newton-meters is equivalent to a Joule)

Even if we do the extra work that is to be made due to the mass of the car and the rolling resistance of the wheels on the ground, take in the magnitude of the work Wf itself, adding the savings in energy (work) is enormous.

At high speeds, a further property of the wheel is critical: The gyroscopic effect causes the wheel like a top stable rotates around its axis and thereby helps the vehicle to a straight-line stability.

Examples:

Hands-free cycling
Would the wheels " eggs ", we would be shaken pretty messed up in the vehicle.

Vehicles with the suffix or prefix " rad"

The concept bike was used for naming vehicles, as

Unicycle
Tricycle
Bike ( bicycle, Niederrad ) and its predecessor unicycle and impeller
Rhönrad ( technically a role, it lacks the axis)
Motorcycle
Radlbock - one -wheeled, wooden, 150-200 cm long barrow, whose two down slightly by curved, cross braced longitudinal beams form the low-lying bed. The rear legs serve as handles and store front Holzspeichenrads with the axis of the axially long Holznabe and iron tires. Two jack stands slightly in front of the handle ends can be designed as steel brackets ( rounded V). A forward stop for the load and thus protect against the wheel form two also braced transversely, slightly forward inclined uprights, which are supported with iron rods near the wheel bearings. For transportation of bulky material such as hay, a chopping block, a mortar chest or a piece of furniture.
Paddle steamer
Wheel loader
Radpanzer

Special cases

The wheel of fire. The unwinding of the fire wheel of a mountain or hill is a popular custom, which is still maintained at Christmas, New Year, Carnival, Easter, and Pentecost of local communities, in Friuli, Odenwald, Sauerland, Spessart, Ticino, Tirol and in the Weser mountain country. To scroll through the fire wheel, a man high wheel is stuffed with straw on the sides before. Most on Shrove Tuesday, the straw is in the dark and lit the wheel, led by the young men of the village on two birch trunks, rolled down a hill. It is believed that the wheel of fire has been a spring tradition for equinox in pre-Christian times, they split after the Christianization in connection with Lent in West Germany and with the Easter season in northern Germany. In such a feast for the spring equinox indicates the chronicle of the monastery of Lorsch. On March 21, 1090, exactly on the date of the equinox, fires have been through such a fire hot, triggered in large parts of the monastery.

In China, vehicles were equipped with oval gears to let you experience the pleasure of this rider a roller-coaster ride. Such test drive offered at us Fairs in the 1920s, today offer us yet some carousels.

Elliptical Gear: If two identical elliptical gears combined, the center distance in operation remains constant. The wheels turn to one of the two foci of the ellipse. The ratio varies over one revolution around the mean i = 1 Only one wheel is elliptical, a wheel has to be mounted on a swing axis. Be used such gears as in weaving. In the 1980s and 90s, some bikes had an elliptical chainring ( Biopace ).

Another special case, which is not used for locomotion, the Ferris wheel, a ride at fairs.

Wheels for the force deflection

To divert attacking forces on hemp or wire ropes, wheels, these applications often called roles installed on stationary axes. The rim is here provided with a circumferential groove to give the rope guide.

Examples are:

The masons role, as seen on small construction sites, where an auxiliary power buckets of material contracts by hand upwards
Conveyor wheels on derricks in pits of mining
Wheels on elevators
The pulley, in which both rollers are installed on stationary, the so-called bottle, as well as to movable, wherein a continuous rope is wrapped around respective pairs of rollers on the two cylinders, that it according to the laws of leverage over a long Seilzugweg higher loads for shorter distances increase.

System wheel and shaft ( wheel )

If the hub of the wheel firmly installed on a supported shaft - see shaft -hub-connection - it can serve to transmit torque or transfer driving forces along a path. The components of the wheel have been modified into various forms for this purpose. Also the wheel may be used as an energy storage ( flywheel ).

Wheelsets of rail vehicles

Rail vehicles usually go on wheels, so to firmly connected by an axle wheels. This design allows the use of larger and more robust wheel bearings and, in combination with tapered treads to sinus run.

Carriers of torque

To transfer torques of the rim is designed according to the type of drive:

A keyed tires made of metal, rubber or plastic on wheels, such as on vehicles
Friction wheel
Pulley or geometry brad with transmission waves
Sheaves / wheels
Gear at, for example gears, clockworks ( chronometer, Astronomical clock ), mechanical calculators, counters as with gas meter and water meter
Sprocket

The collection of friction or gears rotate about the rotational direction. For belt drives is done by twisted by 180 ° belt; rotated by 90 ° belt allow rotation of the plane of rotation from the horizontal to the vertical. By increasing or decreasing the driving wheel, as compared to driving, the angular speed and according to the laws of leverage, the torques of the function can be adapted.

Particularly in gears improvements in efficiency, form-fitting and wear resistance in the embodiments as a function of the given time to the respective materials and processing options have been devised:

Provided laterally in wood with wooden pegs ( cog wheel ) at the rim than crown wheel or with large forces with two wheels as Käfigrad, with cones on the outside of the rim as helical
In metal with various types exported teeth according to the situation of the waves as another spur, bevel, helical or worm gear.

The wheel in machinery

For delivery of forces to be machined materials and media (liquids, vapors, gases) the wheel parts are modified manifold and supplemented so as:

Potter's wheel with Fußantriebsrad to deformation of the clay
Bucket to raise the water level or for irrigation in its earliest form, eg as a wheel with pegs on which jars were connected
Water wheel that is rotated by water power by means of blades or cells in rotation to drive water mills of any kind or oil mills, fulling mills, saw mills, hammer mills and grinding mills
Driven riemenradgetriebene turning or lathe or drill later with an electric motor via gear
Paddlewheel steamers at, that is a double wheel with blades / paddles on the wheel rims
Impeller blowers, centrifugal pumps or centrifugal compressors, ie originally as a wheel with curved blades on the wheel disc, with or without a wreath
Impeller of axial compressors, to produce their seated on the hub blades wing profiled spokes with or without rim
Propeller for propulsion or stirring - are rudimentary, highly specialized versions of the wheel
Drive wheels for the endless ropes of cable cars and gondolas, chairlifts and ski lifts of
Centrifuge for the separation of substances on a vertical axis rotating wheels.

The wheel for torque generation in combustion engines

For power generation and output by humans, animals and the media as the

Simplest, the steering wheel, the steering wheel
Treadmill treadmill mainly for loading and cranes
Bucket as a double with troughs between the wheel rims
Wind turbine for example, in the Mediterranean as a spoke with triangular sails on the spokes and a rope as a kind of rim ( impressively old photos from the valley of the windmills on Crete)
Slow running windmill as a wheel whose spokes are formed as a wing profile and the rim is attached as a stabilizing element against oscillations further inside the wing: eg for pumping water in Majorca, in the plain east of Palma, or on the expansive cattle grazing in the Middle American West
Wheel of steam and gas turbines, which consist seated on the hub blades wing profiled spokes with or without rim
Control and impeller of a turbomachine.

Function as an energy storage

An energy storage ( flywheel rotational energy storage ), the wheel is carried out according to the energy to be absorbed with a sufficiently large mass. It is used in machines which convert reciprocating motion into rotary motion is used to compensate for torque fluctuations. Prevent flywheels that such machines are due to a dead center or at times lack of driving force to a standstill.

Applications:

Flywheel on foot, drives such as in a potter's wheel, spinning wheel or sewing machine
Flywheel of steam or internal combustion engines
Energy storage systems for motive power of vehicles, such as when Gyrobus, friction motor toy, mechanical KERS on racing cars

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