# wheel

Handcarts (two-lane, single-axle) with wooden spoked wheels
Cannon from the Thirty Years War with metal-studded wheels

The wheel is a disk-shaped object with an ideally circular contour , which is rotatably mounted about an axis that is perpendicular to the idealized circular plane and is most often used as a wagon wheel . Its invention and use on carts or wagons was an important event for the development of technical culture in prehistory .

A significant advantage is the rolling of its circumference on the ground. Sliding takes place only in the lubricated bearings. The rolling resistance on firm, dry ground and the sliding resistance in the bearings are together much smaller than the sliding resistance when using a rod loop or a sled to transport a load over dry ground. The material abrasion is also smaller than with grinding. Vehicles and teams with wheels and draft animals became readily available and durable means of transport in prehistory and early history for loads and people.

Already during the Bronze Age the wheel was developed from the disc to the lighter spoked wheel. The spoke shape was created by replacing parts of the disc between the hub and the outer wheel rim with pressure-resistant or tension-resistant, often more special materials and an often sophisticated connection technology.

The simple machine elements include the only turning wheel ( e.g. handwheel , steering wheel ). A vehicle wheel today is a complex technical component .

Rad ( nhd. And ahd. ) Is originally related to the Latin rota and the Sanskrit word ratha , "wagon" .

## history

Funnel beaker dated 3500-3350 BC. BC, on the left the oldest known illustration of a wagon with wheels, found in Bronocice near Działoszyce in Poland
Partially preserved wagon wheels of the Goldberg III group (2900 BC) from the
Federsee Basin Museum
Wagon wheel from Chogha Zanbil , Iran, mid to end of the 2nd millennium BC Chr.
Tehran National Museum
Relief from Amarna , Egypt, approx. 1345–1335 BC BC, Metropolitan Museum of Art , New York
Stader bronze wheels around 1000 BC Chr.

The Sumerian culture was long considered the origin. Today the dates of finds and representations of wagons and wheels from Central and Eastern Europe as well as from Mesopotamia are for the middle of the 4th millennium BC. Chr. In close proximity. A more precise temporal and spatial classification of the invention is not yet possible. In pre-Columbian America and Australia , the wheel was unknown to means of transport.

A little earlier or at the same time, the fast-rotating potter's wheel , which was also provided with slide bearings , became known. An indication that the plain bearing machine element has now been well mastered: lubrication and little play .

### Older transport equipment

The first transport devices that could be used to move loads on land without carrying them were sleds and bar loops . In the case of the loop, however, part of the load and the construction weight has to be carried; the advantage over other means of transport is that it has good cross-country mobility. When using slides and rod loops, there was usually a high level of sliding resistance to overcome. Transport on rollers or cylinders was only possible on well-prepared ground and short distances. There is evidence of a rolling transport from Bronze Age Egypt . The disadvantage was that the rollers had to be laid out over the entire route or had to be repeatedly removed from the rear and placed in front of the object to be transported. But it was possible to shift comparatively high loads, as these are distributed over a larger area than will be found in the plain bearings of the later wheel. The roller transport is still used today for special purposes such as moving buildings or extreme loads over short distances.

### Oldest evidence of the wheel

The rotatably attached wheel, ie "infinitely" rotatable around an axis, could be made with stone tools. Apparently in the 5th millennium BC they were the first to turn. Chr. Potters on the Indus apply this principle to pottery production as pottery wheels.

The oldest evidence can be found in the form of miniature wheels made of clay north of the Black Sea as early as 4000 BC. From the middle of the 4th millennium onwards, the references condense across Europe in the form of car models. Further indirect references to the application as a wagon wheel were found z. B. in the form of incisions on a vessel of the funnel beaker culture in Bronocice near Powiat Pińczowski ( Poland ). Another indirect proof is a lane from the middle of the 4th millennium BC. In a barren bed near Flintbek (Rendsburg-Eckernförde district).

The first direct finds of carts, wheels, wagons or their models come from the second half of the 4th millennium BC. In Europe, e.g. B. in the context of the funnel beaker culture and the Baden culture , in the Alpine foothills , in the northwestern Caucasus ( Maikop culture ), as well as in Mesopotamia and the Middle East. These were one-piece or multi-part disc wheels with diameters between 40 and 80 cm, with fixed, loose or without hub bushing or fixed axle (and square axle holes). The oldest finds were predominantly two-axle vehicles. The finds come either from burials in wagon graves or are bog finds .

The oldest well-dated wheel-axle combination comes from Stare Gmajne in the Laibacher Moor near Ljubljana in Slovenia , whose wheel in the 2σ range was dated to 3340–3030 cal BC, the axle to 3360–3045 cal BC. A little younger bike was found in the Federseemoor in Seekirch -Achwiesen. It is around 5000 years old and made up of two parts

The remains of two chariots were excavated in eastern Georgia under a burial mound in Ananauri ( Kakheti region ) and dated to approx. 2400 ± 150 BC. Dated. This Kurgan probably belongs to a leader from the last phase of the Kura Araxes culture , which has clear connections to the Maikop culture . More detailed investigations are still pending. In addition to obsidian and flint stone, there were also amber beads in the grave. This supports the thesis that the chariot came from the northern region long before the horse and took the route south with the spread of the Kura Araxes culture.

The dating of the sites does not currently allow a decision on the place of origin of the wheel and cart technology.

### Signs of use

One of the four Glum disc wheels from the Bronze Age had a scouring furrow that was not worked into the entire turning circle. It was caused by the car body, which wore off the skewed ("wobbly") wheel. A shorter groove on the other side shows that the wheel has also been turned on. The edge of the tread was beveled or rounded. Some areas were so well preserved that smoothing strokes of a tool can be seen. The wheel made of alder wood belonged to a car whose front axle could not pivot. When changing the direction of travel , the draft animals dragged the front end to the side until the drawbar pointed in the desired direction. Bushes made of birch wood stuck in the socket holes of the wheels , which indicate through their (soft) material that the car was not intended for longer use. Lateral forces (e.g. when changing direction) caused the ends to widen in the shape of a funnel. From other finds it can be deduced that the wheels were removed from parked cars in order to maintain the elasticity of the wooden axles .

### Further developments

Already in the Stone Age people began to reduce the heavy weight of the disc wheels by means of grooves. It is doubtful whether the wheels, grooved with symbolic patterns, were suitable for transporting loads. A metal age invention was the spoke , which was made around 2000 BC. Was introduced in the Orient. The stable and light spoked wheel was used to build so-called chariots , i.e. two-wheeled vehicles that should actually be called carts . Since two-wheeled vehicles were a good way to reduce weight, more sophisticated single-axle vehicles were also built later. If the first spoked wheels had bronze spokes, then in the further course of the Bronze Age and afterwards mainly wooden spoked wheels were built, on which only the inner surface of the wheel hub rubbing on the axle and the outer running surface of the rim were covered with metal . Metal spokes only became the leader again from the 19th century, be it because of higher loads and speeds such as in rail traffic , or after the invention of the spoke lintel made it possible to build very light, stable wheels with thin, tensioned wire spokes , as they are nowadays especially with Bicycle are common.

### The wheel in the New World

The Maya invented the wheel in Mesoamerica . At temples it can also be seen on stone ornaments as a spoked wheel or gear wheel . As previously proven from finds, however, they only used this in applications that did not allow any loads, for example for the wheels to display their calendar and for toys (example in the Ethnological Museum Berlin ). Already in pre-Columbian times they used wheels, even gears, in more or less precision mechanical devices . However, usable wagons have not yet been proven in ancient American cultures. This is most likely due to the lack of suitable draft animals ( horses , oxen , donkeys ).

## materials

Wagon wheel repair

For thousands of years only wood was used as a material . The first spoked wheels had bronze spokes, in the further course of the Bronze Age and afterwards wooden spoked wheels predominated, on which only the inner surface of the wheel hub rubbing on the axle and the outer running surface of the rim were covered with metal. Advances in metallurgy towards more and more resistant metals were then also used here. Only with the invention of the steam engine and the internal combustion engine , which enabled higher transport capacities and speeds, were the wheels made entirely of iron , later of sheet steel welded together as rims . The lubricated hub sleeves were replaced by roller bearings . Lightweight wheels for low loads are provided with wire spokes that are pre-tensioned and subjected to tensile load.

The design of the wheels was always tailored to the surface to be driven on (only later paths and roads), or the surface was improved according to the increased requirements. So came about:

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

Today, hard rubber tires are used on steel wheels as support wheels for. B. for tracked vehicles , for carousels , for cable cars and chair lifts or used in industrial vehicles such as forklifts .

Plastic wheels with or without metal hub or bearings , often without rubber tires are available for mobile tables , scaffolds , ladders (also above), furniture , pallet truck for Euro pallets and Shopping Cart (with webs for clawing on moving walkways ).

Wheels, mostly made of plastic , are used in precision engineering to transmit power, for example to switches.

## System wheel and axle

The wheel and axle system is mainly used for means of transport ; on the one hand on vehicles , on the other hand as a force deflection on hoists . Axles are used to carry loads and are therefore mainly subjected to bending ; Shafts transmit torques and are therefore mainly subjected to torsion .

### Wheels for vehicles

Wheel of a car ( VW 1303 )
Wooden wheel with steel wheel tires from railcar 8 of the FOTG
Car wheel with rubber tires and wooden spokes, hub and rim are made of steel
Front wheel of a bicycle with a wheel hub motor ( Hochhut Technical Collection , Frankfurt - Gallus )

If wheels are mounted rotating on axles with the help of bearings - today mostly only on axle journals - of a vehicle, a significant reduction in the frictional forces and thus energy-saving transport of heavy goods or goods is achieved compared to grinding the object to be transported over a distance to be covered . A fast movement of goods and people , primarily on relatively flat routes .

For comparison: In order to grind or drive a steel plate weighing 100 kg over a distance of ten meters, the following work (corresponding to force times distance) must be performed: The respective frictional force that occurs results from the normal force (corresponding to the mass times the acceleration due to gravity) multiplied by the coefficient of friction . The coefficient of friction for a combination of steel on a rough surface is 0.5, that for steel on steel (smooth) is 0.1. When grinding, the frictional force acts on the rough ground for the entire ten-meter distance, thus the work W s to results

${\ displaystyle W _ {\ mathrm {s}} = 100 \, \ mathrm {kg} \ cdot 9 {,} 81 {\ frac {\ mathrm {N}} {\ mathrm {kg}}} \ cdot 0 {, } 5 \ cdot 10 \, \ mathrm {m} = 4905 \, \ mathrm {J}}$

When driving with wheels with a diameter of 1000 mm and an axle diameter of 50 mm, the path of the steel hub, which rubs against the steel axle, is reduced in the ratio of the diameter and thus the work W f to results

${\ displaystyle W _ {\ mathrm {f}} = 100 \, \ mathrm {kg} \ cdot 9 {,} 81 {\ frac {\ mathrm {N}} {\ mathrm {kg}}} \ cdot 0 {, } 1 \ cdot {\ frac {50 \, \ mathrm {mm}} {1000 \, \ mathrm {mm}}} \ cdot 10 \, \ mathrm {m} = 49 {,} 05 \, \ mathrm {J }}$

(to consider the dimensions : a newton meter is equivalent to a joule)

Even if we assume and add the additional work that has to be done on the ground due to the mass of the car and the rolling resistance of the wheels in the order of magnitude of the work W f itself, the saving in energy (work) is enormous.

At high speeds, another property of the wheel is crucial: the gyroscopic effect causes the wheel to turn stably around its axis like a top, thereby helping the vehicle to keep straight ahead.

The draisine, the forerunner of the bicycle, was already a single-track two-axle two -
wheeler , but did not yet have wire spokes

Examples of this:

• hands-free cycling
• If the wheels were to "wobble", we would be shaken up in the vehicle quite confused.

### Vehicles with the suffix or prefix "rad"

The term wheel was used to name vehicles, as in

• unicycle
• tricycle
• Bicycle (two-wheeled, low-wheeled bicycle ) and its predecessors, high- cycle and balance bike
• Gym wheel (technically a role, the axle is missing)
• motorcycle
• Radlbock - a one-wheeled, wooden, 150–200 cm long wheelbarrow, the two slightly curved, cross-braced longitudinal bars of which form the low-lying loading area. The spars serve as handles at the back and store the axle of the wooden spoke wheel with an axially long wooden hub and iron tires at the front. Two parking supports a little in front of the handle ends can be designed as iron brackets (rounded V). A front stop for the load and thus protection in front of the wheel are formed by two cross braced, slightly forward inclined posts, which are supported by iron bars near the wheel bearings. For transporting voluminous goods such as hay, a chopping stick, a mortar chest or a piece of furniture.
• Armored vehicles

## special cases

Rolling the fire wheel off a mountain or hill is a folk custom that is still practiced today at Christmas, New Year, Carnival, Easter or Whitsun in communities in Friuli , Odenwald , Sauerland , Spessart , Ticino , Tyrol and the Weser Uplands. To roll the fire wheel, a man-high wheel is stuffed with straw on the sides. In the dark, the straw is lit and the wheel, led by the young men of the village on two birch trunks, is rolled down a hill. It is assumed that in pre-Christian times the fire wheel was a spring custom at the equinox , which after Christianization split up into the connection with Lent in southwest Germany and with Easter in northern Germany. The chronicle of the Lorsch monastery also refers to such a festival at the spring equinox . On March 21, 1090, exactly on the equinox , such a fire started fires in large parts of the monastery building.

In China , vehicles have been fitted with oval wheels so that passengers can enjoy a ride up and down the mountain. Such adventure trips were still offered by annual fairs in the 1920s , today we still have some carousels .

Elliptical gear : If two identical elliptical gearwheels are combined, the center distance remains constant during operation. The wheels turn around one of the two focal points of the ellipses. The transmission ratio varies over one revolution around the mean value i = 1. If only one wheel is elliptical, one wheel must be mounted on a swing axle. Such gears are used in weaving machines, for example . In the 1980s and 1990s, some bikes had an elliptical chainring ( Biopace ).

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

## Wheels for power redirection

In order to divert forces acting on hemp or wire ropes, wheels, often called rollers in these applications, are installed stationary on axles. The wheel rim is provided with a circumferential groove to guide the rope.

Examples are:

• the mason's role as seen on small construction sites , where an assistant pulls buckets of material upstairs by hand
• Conveyor wheels on winding towers for mines of mining
• Wheels on elevator systems
• the pulley block , in which both rollers are installed on stationary, so-called bottles, as well as on movable ones, whereby a continuous rope is placed around corresponding pairs of rollers on the two bottles in such a way that, according to the laws of levers , they carry larger loads over shorter ones over a long cable path Lift stretches.

## System wheel and shaft (wheel set)

Wheelset of a class 44 steam locomotive.
Here the wheels are connected by a crankshaft .
The wheelset has a triple drive through three phase-shifted connecting rods , two (typical for the appearance of steam locomotives) on the outside of the wheels and another in the middle.

If the hub of the wheel is permanently installed on a bearing shaft - see shaft-hub connection - it can be used to transmit torques or to transmit drive forces along a path. For this purpose, the components of the wheel were modified into various shapes. The wheel can also be used as an energy store ( flywheel ).

Wheel sets of rail vehicles

Rail vehicles usually run on wheelsets , i.e. on wheels that are firmly connected by an axle . This construction enables larger and more robust wheel bearings to be used and, in combination with conical running surfaces, leads to sinusoidal running .

## Transmitter of torques

To transmit torque , the wheel rim is designed according to the drive type:

Friction or gear wheels that belong together reverse the direction of rotation. In the case of belt drives this is done by twisting the belt by 180 °; Belts rotated by 90 ° enable the plane of rotation to be rotated from the horizontal to the vertical. By increasing or reducing the size of the driven wheel, compared to the driving wheel, the angular speeds and, according to the laws of levers, the torques can be adapted to the function.

Especially with gears, improvements in efficiency , form fit and wear resistance were devised in the designs depending on the materials and processing options available at the respective times:

• in wood with wooden spigots ( sprocket ) on the side of the wheel rim as a crown wheel or with two wheels as a cage wheel, with spigots on the outside of the wheel rim as a spur gear
• in metal with different teeth according to the position of the shafts in relation to each other as a spur, bevel, helical or worm gear.

### The wheel in work machines

To transfer forces to the materials and media to be processed ( liquids , vapors , gases ), the wheel parts are varied and supplemented in a variety of ways, such as:

### The wheel for generating torque in power machines

Steering wheel of a historic DAAG - Post busses

For power generation and output by people, animals and media, such as with

• simplest, the steering wheel , the steering wheel
• Bucket wheel as a double wheel with troughs between the wheel rims
• Wind turbine z. B. in the Mediterranean area as a spoked wheel with triangular sails on the spokes and a rope, as it were, as a wheel rim (impressive on old photos of the valley of the windmills on Crete )
• Slowly running wind turbine as a wheel, the spokes of which are designed as a wing profile and the wheel rim is attached as a stabilizing element against vibrations further inside the wing: z. B. for pumping water on Mallorca , in the plain east of Palma , or on the extensive pastures in the American Midwest
• Impeller of steam and gas turbines , the blades of which on the hub consist of wing-profiled spokes with or without a wheel rim
• Guide and impeller of a turbomachine .

### Function as energy storage

Axle of the first steam locomotive in Germany Adler (replica from 1935) in the Meiningen steam locomotive works

As an energy storage device ( flywheel , rotational energy storage device ), the wheel is designed with a sufficiently large mass according to the energy to be absorbed. It is used in machines that convert reciprocating movements into rotating movements to compensate for torque fluctuations. Flywheels prevent such machines from coming to a standstill due to a dead center or occasional lack of drive power.

Applications:

## Trivia

John Keogh from Hawthorn, Victoria (Australia), registered the wheel as an Australian innovation patent in 2001 , whereby innovation patents are only registered and only examined upon application. He and the Australian Patent Office, which issued him the innovation patent # 2001100012, received the satirical Ig Nobel Prize for Technology in 2001.

## literature

• M. Fansa, S. Burmeister (Ed.): Rad und Wagen. 2004, ISBN 3-8053-3322-6 .
• Köninger et al. (Ed.): Loop, sledge, wheel and carriage. (= Hemmenhofen scripts. Volume 3). Janus publishing house, Freiburg i. Br. 2002, DNB 987282387
• Veronika R. Meyer, Marcel Halbeisen: Only apparently a paradox: Why are there no wheels in nature? In: Biology in Our Time. Volume 36, No. 2, 2006, pp. 120-123,
• Jürgen E. Walkowitz: Logistics in the Neolithic and Chalcolithic. In: Varia neolithica. IV, 2006, ISBN 3-937517-43-X .

Commons : Wheels  - collection of images, videos and audio files
Wiktionary: Rad  - explanations of meanings, word origins, synonyms, translations

## Individual evidence

1. ^ Etymology in the digital dictionary of the German language.
2. Hans JJG Holm: The Earliest Wheel Finds, Their Archeology and Indo-European Terminology in Time and Space, and Early Migrations around the Caucasus. Archaeolingua Alapítvány, Budapest 2019, ISBN 978-615-5766-30-5 .
3. http://www.geschichtsverein-bordesholm.de/Veroeffnahmungen/jahrbuecher/J01_2_Zilch_Flintbek.pdf The Flintbek burial mound after twenty years of excavation, Bernd Zich (PDF file; 2.03 MB)
4. A. Velušček, K. Čufar, M. Zupančič: Prazgodovinsko reado kolo z osjo s kolišča Stare gmajne na Ljubljanskem barju. In: A. Velušček (ed.): Koliščarska naselbina Stare gmajne in njen as. Ljubljansko barje v 2. polovici 4. tisočletja pr. Kr. Opera Instituti Archaeologici Sloveniae 16 (Ljubljana 2009) pp. 197–222. Quoted from Stefan Burmeister: Wagen in the 4th mill. Chr. In: S. Hansen, J. Müller (Hrsg.): Sozialarchäologische Perspektiven: Societal Change 5000–1500 BC Between the Atlantic and the Caucasus. Babble.
5. Almut Bick: The Stone Age . Theiss, 2006, ISBN 3-8062-1996-6 , pp. 13 .
6. Hans JJG Holm: The Earliest Wheel Finds, Their Archeology and Indo-European Terminology in Time and Space, and Early Migrations around the Caucasus. In: Archaeolingua Alapítvány. Budapest 2019, ISBN 978-615-5766-30-5 , p. 113.
7. Discovered ancient wagon grave
8. Patent # 2001100012 at the Australian Patent Office ( PDF , English; 632 kB)
9. Ig Nobel Prizes 2011