Crank (mechanism)
Encyclopedia
Reciprocating motion
Reciprocating motion, also called reciprocation, is a repetitive up-and-down or back-and-forth motion. It is found in a wide range of mechanisms, including reciprocating engines and pumps. The two opposite motions that comprise a single reciprocation cycle are called strokes...
is imparted to or received from the shaft. It is used to change circular into reciprocating motion, or reciprocating into circular motion
Circular motion
In physics, circular motion is rotation along a circular path or a circular orbit. It can be uniform, that is, with constant angular rate of rotation , or non-uniform, that is, with a changing rate of rotation. The rotation around a fixed axis of a three-dimensional body involves circular motion of...
. The arm may be a bent portion of the shaft, or a separate arm attached to it. Attached to the end of the crank by a pivot is a rod, usually called a connecting rod
Connecting rod
In a reciprocating piston engine, the connecting rod or conrod connects the piston to the crank or crankshaft. Together with the crank, they form a simple mechanism that converts linear motion into rotating motion....
. The end of the rod attached to the crank moves in a circular motion, while the other end is usually constrained to move in a linear
Linear motion
Linear motion is motion along a straight line, and can therefore be described mathematically using only one spatial dimension. The linear motion can be of two types: uniform linear motion, with constant velocity or zero acceleration; non uniform linear motion, with variable velocity or non-zero...
sliding motion, in and out.
The term often refers to a human-powered crank which is used to manually turn an axle, as in a bicycle
Bicycle
A bicycle, also known as a bike, pushbike or cycle, is a human-powered, pedal-driven, single-track vehicle, having two wheels attached to a frame, one behind the other. A person who rides a bicycle is called a cyclist, or bicyclist....
crankset
Crankset
The crankset or chainset , is the component of a bicycle drivetrain that converts the reciprocating motion of the rider's legs into rotational motion used to drive the chain, which in turn drives the rear wheel...
or a brace and bit drill. In this case a person's arm or leg serves as the connecting rod, applying reciprocating force to the crank. Often there is a bar perpendicular to the other end of the arm, often with a freely rotatable handle on it to hold in the hand, or in the case of operation by a foot (usually with a second arm for the other foot), with a freely rotatable pedal.
Examples
Familiar examples include:Hand-powered cranks
- Mechanical pencil sharpenerPencil sharpenerA pencil sharpener is a device for sharpening a pencil's writing point by shaving away its worn surface. Pencil sharpeners may be operated manually or by an electric motor.-History:...
- Fishing reelFishing reelA fishing reel is a "cylindrical device attached to a fishing rod used in winding the line". Modern fishing reels usually have fittings which make it easier to retrieve the line and deploy it for better accuracy or distance. Fishing reels are traditionally used in the recreational sport of angling...
and other reelReelA reel is an object around which lengths of another material are wound for storage. Generally a reel has a cylindrical core and walls on the sides to retain the material wound around the core...
s for cables, wires, ropes, etc. - Manually operated car window
- The crank set that drives a trikkeTrikkethumb|The Trikke works by shifting body weightThe Trikke three-wheeled cambering vehicles are human powered machines that utilize Trikke Tech’s patented technology to allow a rider to propel a chainless, pedal-less device forward without ever touching foot to ground...
through its handles.
Foot-powered cranks
- The crankset that drives a bicycle via the pedals.
- TreadleTreadleA treadle [from OE tredan = to tread] is a part of a machine which is operated by the foot to produce reciprocating or rotary motion in a machine such as a weaving loom or grinder...
sewing machineSewing machineA sewing machine is a textile machine used to stitch fabric, cards and other material together with thread. Sewing machines were invented during the first Industrial Revolution to decrease the amount of manual sewing work performed in clothing companies...
Engines
Almost all reciprocating engineReciprocating engine
A reciprocating engine, also often known as a piston engine, is a heat engine that uses one or more reciprocating pistons to convert pressure into a rotating motion. This article describes the common features of all types...
s use cranks to transform the back-and-forth motion of the pistons into rotary motion. The cranks are incorporated into a crankshaft
Crankshaft
The crankshaft, sometimes casually abbreviated to crank, is the part of an engine which translates reciprocating linear piston motion into rotation...
.
Mechanics
The displacement of the end of the connecting rod is approximately proportional to the cosine of the angleAngle
In geometry, an angle is the figure formed by two rays sharing a common endpoint, called the vertex of the angle.Angles are usually presumed to be in a Euclidean plane with the circle taken for standard with regard to direction. In fact, an angle is frequently viewed as a measure of an circular arc...
of rotation of the crank, when it is measured from top dead center (TDC). So the reciprocating motion created by a steadily rotating crank and connecting rod is approximately simple harmonic motion
Simple harmonic motion
Simple harmonic motion can serve as a mathematical model of a variety of motions, such as the oscillation of a spring. Additionally, other phenomena can be approximated by simple harmonic motion, including the motion of a simple pendulum and molecular vibration....
:
where x is the distance of the end of the connecting rod from the crank axle, l is the length of the connecting rod, r is the length of the crank, and α is the angle of the crank measured from top dead center (TDC). Technically, the reciprocating motion of the connecting rod departs slightly from sinusoidal motion due to the changing angle of the connecting rod during the cycle.
The mechanical advantage
Mechanical advantage
Mechanical advantage is a measure of the force amplification achieved by using a tool, mechanical device or machine system. Ideally, the device preserves the input power and simply trades off forces against movement to obtain a desired amplification in the output force...
of a crank, the ratio between the force on the connecting rod and the torque
Torque
Torque, moment or moment of force , is the tendency of a force to rotate an object about an axis, fulcrum, or pivot. Just as a force is a push or a pull, a torque can be thought of as a twist....
on the shaft, varies throughout the crank's cycle. The relationship between the two is approximately:
where
is the torque and F is the force on the connecting rod. For a given force on the crank, the torque is maximum at crank angles of α = 90° or 270° from TDC. When the crank is driven by the connecting rod, a problem arises when the crank is at top dead centre (0°) or bottom dead centre (180°). At these points in the crank's cycle, a force on the connecting rod causes no torque on the crank. Therefore if the crank is stationary and happens to be at one of these two points, it cannot be started moving by the connecting rod. For this reason, in steam locomotiveSteam locomotive
A steam locomotive is a railway locomotive that produces its power through a steam engine. These locomotives are fueled by burning some combustible material, usually coal, wood or oil, to produce steam in a boiler, which drives the steam engine...
s, whose wheels are driven by cranks, the two connecting rods are attached to the wheels at points 90° apart, so that regardless of the position of the wheels when the engine starts, at least one connecting rod will be able to exert torque to start the train.
Classical Antiquity
The eccentrically mounted handle of the rotary handmillQuern-stone
Quern-stones are stone tools for hand grinding a wide variety of materials. They were used in pairs. The lower, stationary, stone is called a quern, whilst the upper, mobile, stone is called a handstone...
which appeared in 5th century BC Celtiberian
Celtiberians
The Celtiberians were Celtic-speaking people of the Iberian Peninsula in the final centuries BC. The group used the Celtic Celtiberian language.Archaeologically, the Celtiberians participated in the Hallstatt culture in what is now north-central Spain...
Spain
Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...
and ultimately spread across the Roman Empire
Roman Empire
The Roman Empire was the post-Republican period of the ancient Roman civilization, characterised by an autocratic form of government and large territorial holdings in Europe and around the Mediterranean....
constitutes a crank. A Roman iron crankshaft of yet unknown purpose dating to the 2nd century AD was excavated in Augusta Raurica
Augusta Raurica
Augusta Raurica is a Roman archaeological site and an open-air museum in Switzerland. Located on the south bank of the Rhine river about 20 km east of Basel near the villages of Augst and Kaiseraugst, it is the oldest known Roman colony on the Rhine....
, Switzerland
Switzerland
Switzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....
. The 82.5 cm long piece has fitted to one end a 15 cm long bronze handle, the other handle being lost.
A ca. 40 cm long true iron crank was excavated, along with a pair of shattered mill-stones of 50−65 cm diameter and diverse iron items, in Aschheim
Aschheim
Aschheim is a municipality in the district of Munich in Bavaria in Germany.Aschheim is the location of BMW's test track which the manufacturer opened in 1972....
, close to Munich
Munich
Munich The city's motto is "" . Before 2006, it was "Weltstadt mit Herz" . Its native name, , is derived from the Old High German Munichen, meaning "by the monks' place". The city's name derives from the monks of the Benedictine order who founded the city; hence the monk depicted on the city's coat...
. The crank-operated Roman
Ancient Rome
Ancient Rome was a thriving civilization that grew on the Italian Peninsula as early as the 8th century BC. Located along the Mediterranean Sea and centered on the city of Rome, it expanded to one of the largest empires in the ancient world....
mill is dated to the late 2nd century AD. An often cited modern reconstruction of a bucket-chain pump driven by hand-cranked flywheel
Flywheel
A flywheel is a rotating mechanical device that is used to store rotational energy. Flywheels have a significant moment of inertia, and thus resist changes in rotational speed. The amount of energy stored in a flywheel is proportional to the square of its rotational speed...
s from the Nemi ships
Nemi ships
The Nemi Ships were ships built by the Roman emperor Caligula in the 1st century AD at Lake Nemi. Although the purpose of the ships is only speculated on, the larger ship was essentially an elaborate floating palace, which contained quantities of marble, mosaic floors, heating and plumbing such as...
has been dismissed though as "archaeological fantasy".
The earliest evidence, anywhere in the world, for the crank combined with a connecting rod in a machine appears in the late Roman Hierapolis sawmill
Hierapolis sawmill
The Hierapolis sawmill was a Roman water-powered stone sawmill at Hierapolis, Asia Minor . Dating to the second half of the 3rd century AD, the sawmill is the earliest known machine to combine a crank with a connecting rod....
from the 3rd century AD and two Roman stone sawmill
Sawmill
A sawmill is a facility where logs are cut into boards.-Sawmill process:A sawmill's basic operation is much like those of hundreds of years ago; a log enters on one end and dimensional lumber exits on the other end....
s at Gerasa, Roman Syria, and Ephesus
Ephesus
Ephesus was an ancient Greek city, and later a major Roman city, on the west coast of Asia Minor, near present-day Selçuk, Izmir Province, Turkey. It was one of the twelve cities of the Ionian League during the Classical Greek era...
, Asia Minor
Asia Minor
Asia Minor is a geographical location at the westernmost protrusion of Asia, also called Anatolia, and corresponds to the western two thirds of the Asian part of Turkey...
(both 6th century AD). On the pediment
Pediment
A pediment is a classical architectural element consisting of the triangular section found above the horizontal structure , typically supported by columns. The gable end of the pediment is surrounded by the cornice moulding...
of the Hierapolis mill, a waterwheel fed by a mill race
Mill race
A mill race, raceway or mill lade is the current or channel of a stream, especially one for conducting water to or from a water wheel or other device for utilizing its energy...
is shown powering via a gear train
Gear train
A gear train is formed by mounting gears on a frame so that the teeth of the gears engage. Gear teeth are designed to ensure the pitch circles of engaging gears roll on each other without slipping, this provides a smooth transmission of rotation from one gear to the next.The transmission of...
two frame saw
Frame saw
Frame saw sometimes refers to a woodworker's bow saw.A frame saw is a type of rip saw. It consists of a relatively narrow and flexible blade held under tension within a rectangular frame...
s which cut rectangular blocks by the way of some kind of connecting rods and, through mechanical necessity, cranks. The accompanying inscription is in Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
.
The crank and connecting rod mechanisms of the other two archaeologically attested sawmills worked without a gear train. In ancient literature, we find a reference to the workings of water-powered marble
Marble
Marble is a metamorphic rock composed of recrystallized carbonate minerals, most commonly calcite or dolomite.Geologists use the term "marble" to refer to metamorphosed limestone; however stonemasons use the term more broadly to encompass unmetamorphosed limestone.Marble is commonly used for...
saws close to Trier
Trier
Trier, historically called in English Treves is a city in Germany on the banks of the Moselle. It is the oldest city in Germany, founded in or before 16 BC....
, now Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
, by the late 4th century poet Ausonius
Ausonius
Decimius Magnus Ausonius was a Latin poet and rhetorician, born at Burdigala .-Biography:Decimius Magnus Ausonius was born in Bordeaux in ca. 310. His father was a noted physician of Greek ancestry and his mother was descended on both sides from long-established aristocratic Gallo-Roman families...
; about the same time, these mill types seem also to be indicated by the Christian saint Gregory of Nyssa
Gregory of Nyssa
St. Gregory of Nyssa was a Christian bishop and saint. He was a younger brother of Basil the Great and a good friend of Gregory of Nazianzus. His significance has long been recognized in the Eastern Orthodox, Oriental Orthodox, Eastern Catholic and Roman Catholic branches of Christianity...
from Anatolia
Anatolia
Anatolia is a geographic and historical term denoting the westernmost protrusion of Asia, comprising the majority of the Republic of Turkey...
, demonstrating a diversified use of water-power in many parts of the Roman Empire The three finds push back the date of the invention of the crank and connecting rod back by a full millennium; for the first time, all essential components of the much later steam engine
Steam engine
A steam engine is a heat engine that performs mechanical work using steam as its working fluid.Steam engines are external combustion engines, where the working fluid is separate from the combustion products. Non-combustion heat sources such as solar power, nuclear power or geothermal energy may be...
were assembled by one technological culture:
Middle Ages
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Grindstone (tool)
A grindstone is a round sharpening stone used for grinding or sharpening ferrous tools. They are usually made from sandstone.Grindstone machines usually have pedals in which to speed and slow the stone to sharpen metal to the point of perfection....
− the earliest representation thereof − which is operated by a crank handle is shown in the Carolingian manuscript Utrecht Psalter
Utrecht Psalter
The Utrecht Psalter is a ninth century illuminated psalter which is a key masterpiece of Carolingian art; it is probably the most valuable manuscript in the Netherlands. It is famous for its 166 lively pen illustrations, with one accompanying each psalm and the other texts in the manuscript...
; the pen drawing of around 830 goes back to a late antique original. A musical tract ascribed to the abbot Odo of Cluny
Odo of Cluny
Saint Odo of Cluny , a saint of the Roman Catholic Church, was the second abbot of Cluny. He enacted various reforms in the Cluniac monastery system of France and Italy....
(ca. 878−942) describes a fretted stringed instrument which was sounded by a resined wheel turned with a crank; the device later appears in two 12th century illuminated manuscripts. There are also two pictures of Fortuna
Fortuna
Fortuna can mean:*Fortuna, the Roman goddess of luck -Geographical:*19 Fortuna, asteroid*Fortuna, California, town located on the north coast of California*Fortuna, United States Virgin Islands...
cranking her wheel of destiny from this and the following century.
The use of crank handles in trepanation drills was depicted in the 1887 edition of the Dictionnaire des Antiquités Grecques et Romaines
Dictionnaire des Antiquités Grecques et Romaines
The Dictionnaire des Antiquités Grecques et Romaines d'après les textes et les monuments, contenant l'explication des termes qui se rapportent aux mœurs, aux institutions, à la religion, aux arts, aux sciences, au costume, au mobilier, à la guerre, à la marine, aux métiers, aux monnaies, poids et...
to the credit of the Spanish Muslim
Al-Andalus
Al-Andalus was the Arabic name given to a nation and territorial region also commonly referred to as Moorish Iberia. The name describes parts of the Iberian Peninsula and Septimania governed by Muslims , at various times in the period between 711 and 1492, although the territorial boundaries...
surgeon Abu al-Qasim al-Zahrawi; however, the existence of such a device cannot be confirmed by the original illuminations and thus has to be discounted. The Benedictine
Benedictine
Benedictine refers to the spirituality and consecrated life in accordance with the Rule of St Benedict, written by Benedict of Nursia in the sixth century for the cenobitic communities he founded in central Italy. The most notable of these is Monte Cassino, the first monastery founded by Benedict...
monk Theophilus Presbyter
Theophilus Presbyter
Theophilus Presbyter is the pseudonymous author or compiler ofa Latin text containing detailed descriptions of various medieval arts, a text commonly known as the Schedula diversarum artium or De diversis artibus , probably first compiled between 1100 and 1120...
(c. 1070−1125) described crank handles "used in the turning of casting cores".
The Italian physician Guido da Vigevano
Guido da Vigevano
Guido da Vigevano was an Italian physician and inventor. He is notable for his sketchbook Texaurus regis Francie which depicts a number of technological items and ingenious devices, allowing modern scholarship an invaluable insight into the state of medieval technology...
(c. 1280−1349), planning for a new crusade, made illustrations for a paddle boat
Paddle boat
Paddle boat may refer to:* Paddle steamer or paddleboat, a boat propelled by a paddle wheel* Pedalo, a boat propelled by pedalling with the feet* A boat which is paddled, such as a canoe or kayak...
and war carriages that were propelled by manually turned compound cranks and gear wheels (center of image). The Luttrell Psalter
Luttrell Psalter
The Luttrell Psalter is an illuminated manuscript written and illustrated circa 1320 – 1340 by anonymous scribes and artists...
, dating to around 1340, describes a grindstone which was rotated by two cranks, one at each end of its axle; the geared hand-mill, operated either with one or two cranks, appeared later in the 15th century;
Medieval crane
Crane (machine)
A crane is a type of machine, generally equipped with a hoist, wire ropes or chains, and sheaves, that can be used both to lift and lower materials and to move them horizontally. It uses one or more simple machines to create mechanical advantage and thus move loads beyond the normal capability of...
s were occasionally powered by cranks, although more often by windlass
Windlass
The windlass is an apparatus for moving heavy weights. Typically, a windlass consists of a horizontal cylinder , which is rotated by the turn of a crank or belt...
es.
Renaissance
The crank became common in Europe by the early 15th century, often seen in the works of those such as the GermanGermans
The Germans are a Germanic ethnic group native to Central Europe. The English term Germans has referred to the German-speaking population of the Holy Roman Empire since the Late Middle Ages....
military engineer Konrad Kyeser
Konrad Kyeser
Konrad Kyeser was a German military engineer, author of Bellifortis , a book on siege engines popular throughout the 15th century...
. Devices depicted in Kyeser's Bellifortis
Bellifortis
Bellifortis is the first fully illustrated manual of military technology, dating from the start of the 15th century...
include cranked windlasses (instead of spoke-wheels) for spanning siege crossbows, cranked chain of buckets for water-lifting and cranks fitted to a wheel of bells. Kyeser also equipped the Archimedes screws for water-raising with a crank handle, an innovation which subsequently replaced the ancient practice of working the pipe by treading. The earliest evidence for the fitting of a well-hoist with cranks is found in a miniature of c. 1425 in the German Hausbuch of the Mendel Foundation.
The first depictions of the compound crank in the carpenter's brace
Brace (tool)
A brace or brace and bit is a hand tool used to drill holes, usually in wood. Pressure is applied to the top and the tool is rotated with a U-shaped grip....
appear between 1420 and 1430 in various northern European artwork. The rapid adoption of the compound crank can be traced in the works of the Anonymous of the Hussite Wars, an unknown German engineer writing on the state of the military technology of his day: first, the connecting-rod, applied to cranks, reappeared, second, double compound cranks also began to be equipped with connecting-rods and third, the flywheel was employed for these cranks to get them over the 'dead-spot'.
One of the drawings of the Anonymous of the Hussite Wars shows a boat with a pair of paddle-wheels at each end turned by men operating compound cranks (see above). The concept was much improved by the Italian Roberto Valturio
Roberto Valturio
Roberto Valturio was an Italian engineer and writer born in Rimini. He was the author of the military treatise De Re militari .-References:...
in 1463, who devised a boat with five sets, where the parallel cranks are all joined to a single power source by one connecting-rod, an idea also taken up by his compatriot Francesco di Giorgio
Francesco di Giorgio
Francesco di Giorgio Martini was an Italian painter of the Sienese School and a sculptor, as well as being, in Nikolaus Pevsner's terms, "one of the most interesting later Quattrocento architects'" and a visionary architectural theorist; as a military engineer he executed architectural designs and...
.
In Renaissance Italy, the earliest evidence of a compound crank and connecting-rod is found in the sketch books of Taccola
Taccola
Mariano di Jacopo detto il Taccola , called Taccola , was an Italian administrator, artist and engineer of the early Renaissance. Taccola is known for his technological treatises De ingeneis and De machinis, which feature annotated drawings of a wide array of innovative machines and devices...
, but the device is still mechanically misunderstood. A sound grasp of the crank motion involved demonstrates a little later Pisanello
Pisanello
Pisanello , known professionally as Antonio di Puccio Pisano or Antonio di Puccio da Cereto, also erroneously called Vittore Pisano by Giorgio Vasari, was one of the most distinguished painters of the early Italian Renaissance and Quattrocento...
who painted a piston-pump driven
by a water-wheel and operated by two simple cranks and two connecting-rods.
The 15th century also saw the introduction of cranked rack-and-pinion devices, called cranequins, which were fitted to the crossbow
Crossbow
A crossbow is a weapon consisting of a bow mounted on a stock that shoots projectiles, often called bolts or quarrels. The medieval crossbow was called by many names, most of which derived from the word ballista, a torsion engine resembling a crossbow in appearance.Historically, crossbows played a...
's stock as a means of exerting even more force while spanning the missile weapon (see right). In the textile industry, cranked reel
Reel
A reel is an object around which lengths of another material are wound for storage. Generally a reel has a cylindrical core and walls on the sides to retain the material wound around the core...
s for winding skeins of yarn were introduced.
Around 1480, the early medieval rotary grindstone was improved with a treadle and crank mechanism. Cranks mounted on push-carts first appear in a German engraving of 1589.
From the 16th century onwards, evidence of cranks and connecting rods integrated into machine design becomes abundant in the technological treatises of the period: Agostino Ramelli
Agostino Ramelli
Agostino Ramelli was an engineer who designed the "book wheel" or "reading wheel".During the Siege of La Rochelle , Agostino successfully engineered a mine under a bastion and breached the fortification, making him popular with his commander, Henri d'Anjou, who later became Henri III of France.In...
's The Diverse and Artifactitious Machines of 1588 alone depicts eighteen examples, a number which rises in the Theatrum Machinarum Novum by Georg Andreas Böckler
Georg Andreas Böckler
Georg Andreas Böckler was a German architect and engineer who wrote Architectura Curiosa Nova and Theatrum Machinarum Novum ....
to 45 different machines, one third of the total.
Far East
Bellows
A bellows is a device for delivering pressurized air in a controlled quantity to a controlled location.Basically, a bellows is a deformable container which has an outlet nozzle. When the volume of the bellows is decreased, the air escapes through the outlet...
, and in the well windlass. However, the potential of the crank of converting circular motion into reciprocal one never seems to have been fully realized in China, and the crank was typically absent from such machines until the turn of the 20th century.
Middle East
While the US-American historian of technology Lynn White could not find "firm evidence of even the simplest application of the crank until al-JazariAl-Jazari
Abū al-'Iz Ibn Ismā'īl ibn al-Razāz al-Jazarī was a Muslim polymath: a scholar, inventor, mechanical engineer, craftsman, artist, mathematician and astronomer from Al-Jazira, Mesopotamia, who lived during the Islamic Golden Age...
's book of A.D. 1206", the crank appears according to Beeston in the mid-9th century in several of the hydraulic devices described by the Banū Mūsā
Banu Musa
The Banū Mūsā brothers , namely Abū Jaʿfar Muḥammad ibn Mūsā ibn Shākir , Abū al‐Qāsim Aḥmad ibn Mūsā ibn Shākir and Al-Ḥasan ibn Mūsā ibn Shākir , were three 9th-century Persian scholars of Baghdad who are known for their Book of Ingenious Devices on automata and mechanical devices...
brothers in their Book of Ingenious Devices
Book of Ingenious Devices
The Book of Ingenious Devices was a large illustrated work on mechanical devices, including automata, published in 850 by the three Persian brothers known as the Banu Musa working at the House of Wisdom in Baghdad, Iraq, under the Abbasid Caliphate...
. These devices, however, made only partial rotations and could not transmit much power, although only a small modification would have been required to convert it to a crankshaft.
Al-Jazari (1136–1206) described a crank and connecting rod system in a rotating machine in two of his water-raising machines. His twin-cylinder pump
Pump
A pump is a device used to move fluids, such as liquids, gases or slurries.A pump displaces a volume by physical or mechanical action. Pumps fall into three major groups: direct lift, displacement, and gravity pumps...
incorporated a crankshaft, but the device was unnecessarily complex indicating that he still did not fully understand the concept of power conversion. After al-Jazari cranks in Islamic technology are not traceable until an early 15th century copy of the Mechanics of the ancient Greek engineer Hero of Alexandria.
Cranks were formerly common on some machines in the early 20th century; for example almost all phonograph
Phonograph
The phonograph record player, or gramophone is a device introduced in 1877 that has had continued common use for reproducing sound recordings, although when first developed, the phonograph was used to both record and reproduce sounds...
s before the 1930s were powered by clockwork
Clockwork
A clockwork is the inner workings of either a mechanical clock or a device that operates in a similar fashion. Specifically, the term refers to a mechanical device utilizing a complex series of gears....
motors wound with cranks, and internal combustion engine
Internal combustion engine
The internal combustion engine is an engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber. In an internal combustion engine, the expansion of the high-temperature and high -pressure gases produced by combustion apply direct force to some component of the engine...
s of automobile
Automobile
An automobile, autocar, motor car or car is a wheeled motor vehicle used for transporting passengers, which also carries its own engine or motor...
s were usually started with cranks (known as starting handles in the UK), before electric starters
Automobile self starter
A starter motor is an electric motor for rotating an internal-combustion engine so as to initiate the engine's operation under its own power.- History :...
came into general use.
See also
- WinchWinchA winch is a mechanical device that is used to pull in or let out or otherwise adjust the "tension" of a rope or wire rope . In its simplest form it consists of a spool and attached hand crank. In larger forms, winches stand at the heart of machines as diverse as tow trucks, steam shovels and...
- Piston motion equations
- Nothing grinder
- Sun and planet gearSun and planet gearThe sun and planet gear was a method of converting reciprocal motion to rotary motion and was utilised in a reciprocating steam engine....
External links
- Crank highlight: Hypervideo of construction and operation of a four cylinder internal combustion engine courtesy of Ford Motor Company
- Kinematic Models for Design Digital Library (KMODDL) - Movies and photos of hundreds of working mechanical-systems models at Cornell University. Also includes an e-book library of classic texts on mechanical design and engineering.