A sprocket[1] or sprocket-wheel[2] is a profiled wheel with teeth, or cogs,[3][4] that mesh with a chain, track or other perforated or indented material.[5][6] The name 'sprocket' applies generally to any wheel upon which radial projections engage a chain passing over it. It is distinguished from a gear in that sprockets are never meshed together directly, and differs from a pulley in that sprockets have teeth and pulleys are smooth.

Sprockets are used in bicycles, motorcycles, cars, tracked vehicles, and other machinery either to transmit rotary motion between two shafts where gears are unsuitable or to impart linear motion to a track, tape etc. Perhaps the most common form of sprocket may be found in the bicycle, in which the pedal shaft carries a large sprocket-wheel, which drives a chain, which, in turn, drives a small sprocket on the axle of the rear wheel. Early automobiles were also largely driven by sprocket and chain mechanism, a practice largely copied from bicycles.

Sprockets are of various designs, a maximum of efficiency being claimed for each by its originator. Sprockets typically do not have a flange. Some sprockets used with timing belts have flanges to keep the timing belt centered. Sprockets and chains are also used for power transmission from one shaft to another where slippage is not admissible, sprocket chains being used instead of belts or ropes and sprocket-wheels instead of pulleys. They can be run at high speed and some forms of chain are so constructed as to be noiseless even at high speed.

16 tooth sprocket. Do = Sprocket diameter. Dp = Pitch diameter
A sprocket and roller chain


The term 'sprocket' originally applied to the projection from the wheel that caught on the chain and provided the drive to it. The overall wheel was then termed a 'sprocket wheel'. With time and common use of these devices, the overall wheel became known as a sprocket. The earlier uses would now be seen as archaic.


In the case of bicycle chains, it is possible to modify the overall gear ratio of the chain drive by varying the diameter (and therefore, the tooth count) of the sprockets on each side of the chain. This is the basis of derailleur gears. A multi-speed bicycle, by providing two or three different-sized driving sprockets and up to 12 (as of 2018) different-sized driven sprockets, allows up to 36 different gear ratios. The resulting lower gear ratios make the bike easier to pedal up hills while the higher gear ratios make the bike more powerful to pedal on flats and downhills. In a similar way, manually changing the sprockets on a motorcycle can change the characteristics of acceleration and top speed by modifying the final drive gear ratio. The final drive gear ratio can be calculated by dividing the number of teeth on the rear sprocket by the number of teeth on the counter-shaft sprocket. With respect to the stock gearing on a motorcycle, installing a smaller counter-shaft sprocket (less teeth), or a larger rear sprocket (more teeth), produces a lower gear ratio, which increases the acceleration of the motorcycle but decreases its top speed. Installing a larger counter-shaft sprocket, or a smaller rear sprocket, produces a higher gear ratio, which decreases the acceleration of the motorcycle but increases its top speed.

Tracked vehicles

Leclerc p1040882
Tread drive sprocket of the Leclerc main battle tank (2006).

In the case of vehicles with caterpillar tracks the engine-driven toothed-wheel transmitting motion to the tracks is known as the drive sprocket and may be positioned at the front or back of the vehicle, or in some cases both. There may also be a third sprocket, elevated, driving the track.

Film and paper

Optic Projection fig 226
Moving picture mechanism from 1914. The sprocket wheels a, b, and c engage and transport the film. a and b move with uniform velocity and c indexes each frame of the film into place for projection.

Sprockets are used in the film transport mechanisms of movie projectors and movie cameras.[7] In this case, the sprocket wheels engage film perforations in the film stock. Sprocket feed was also used for punched tape and is used for paper feed to some computer printers.

See also


  1. ^ "Sprocket - Definition". Merriam-Webster. Retrieved 2011-11-14. sprocket, n. 1: a toothed wheel whose teeth engage the links of a chain
  2. ^ Oxford English Dictionary (2nd ed.). Oxford University Press. 1989. sprocket, n. 2. b. ellipt. A sprocket-wheel, esp. that of a cycle; and (Cinematogr.), one that propels film by engaging with perforations along its edge.
  3. ^ Oxford English Dictionary (2nd ed.). Oxford University Press. 1989. cog, n. 1. a. One of a series of teeth or similar projections on the circumference of a wheel, or the side of a bar, etc., which, by engaging with corresponding projections on another wheel, etc., transmit or receive motion.
  4. ^ Oxford English Dictionary (2nd ed.). Oxford University Press. 1989. sprocket, n. 2. a. A projection (either forked or simple) from the rim of a wheel, engaging with the links of a chain.
  5. ^ The Encyclopedia Americana: a library of universal knowledge, sprocket. pg 460
  6. ^ Elements of machine design By Oscar Adolph Leutwiler
  7. ^ Motion picture handbook By Frank Herbert Richardson

External links

Action Masters

Action Masters are a sub-line of the Transformers toy franchise, first released in 1990, with a wave of new releases released in Europe in 1991. It featured Transformers action figures who were unable to transform, but came with transforming partners, weapons or exo-suits. Some of the larger sets came with transforming vehicles or bases. This was the last sub-line release as part of the original Transformers toyline before the launch of Generation 2.

Bicycle gearing

Bicycle gearing is the aspect of a bicycle drivetrain that determines the relation between the cadence, the rate at which the rider pedals, and the rate at which the drive wheel turns.

On some bicycles, there is only one gear and the gear ratio is fixed. Many contemporary bicycles have multiple gears and thus multiple gear ratios. A shifting mechanism allows selection of the appropriate gear ratio for efficiency or comfort under the prevailing circumstances: for example, it may be comfortable to use a high gear when cycling downhill, a medium gear when cycling on a flat road, and a low gear when cycling uphill. Different gear ratios and gear ranges are appropriate for different people and styles of cycling.

A cyclist's legs produce power optimally within a narrow pedalling speed range, or cadence. Gearing can be optimized to use this narrow range as efficiently as possible. As in other types of transmissions, the gear ratio is closely related to the mechanical advantage of the drivetrain of the bicycle. On single-speed bicycles and multi-speed bicycles using derailleur gears, the gear ratio depends on the ratio of the number of teeth on the chainring to the number of teeth on the rear sprocket (cog). For bicycles equipped with hub gears, the gear ratio also depends on the internal planetary gears within the hub. For a shaft-driven bicycle the gear ratio depends on the bevel gears used at each end of the shaft.

For a bicycle to travel at the same speed, using a lower gear (larger mechanical advantage) requires the rider to pedal at a faster cadence, but with less force. Conversely, a higher gear (smaller mechanical advantage) provides a higher speed for a given cadence, but requires the rider to exert greater force. Different cyclists may have different preferences for cadence and pedaling force. Prolonged exertion of too much force in too high a gear at too low a cadence can increase the chance of knee damage; cadence above 100 rpm becomes less effective after short bursts, as during a sprint.

Caterpillar D10

The Caterpillar D10 is a track-type tractor manufactured by Caterpillar Inc. (then called the Caterpillar Tractor Company). It was the first modern tractor to use the elevated drive sprocket to improve durability, operator comfort, and ease of maintenance.

Chain drive

Chain drive is a way of transmitting mechanical power from one place to another. It is often used to convey power to the wheels of a vehicle, particularly bicycles and motorcycles. It is also used in a wide variety of machines besides vehicles.

Most often, the power is conveyed by a roller chain, known as the drive chain or transmission chain, passing over a sprocket gear, with the teeth of the gear meshing with the holes in the links of the chain. The gear is turned, and this pulls the chain putting mechanical force into the system. Another type of drive chain is the Morse chain, invented by the Morse Chain Company of Ithaca, New York, United States. This has inverted teeth.Sometimes the power is output by simply rotating the chain, which can be used to lift or drag objects. In other situations, a second gear is placed and the power is recovered by attaching shafts or hubs to this gear. Though drive chains are often simple oval loops, they can also go around corners by placing more than two gears along the chain; gears that do not put power into the system or transmit it out are generally known as idler-wheels. By varying the diameter of the input and output gears with respect to each other, the gear ratio can be altered. For example, when the bicycle pedals' gear rotate once, it causes the gear that drives the wheels to rotate more than one revolution.


On a bicycle, the cogset or cluster is the set of multiple sprockets that attaches to the hub on the rear wheel. A cogset works with a rear derailleur to provide multiple gear ratios to the rider. Cogsets come in two varieties, freewheels or cassettes, of which cassettes are a newer development. Although cassettes and freewheels perform the same function and look almost the same when installed, they have important mechanical differences and are not interchangeable.

Continuous stationery

Continuous stationery (UK) or continuous form paper (US) is paper which is designed for use with dot-matrix and line printers with appropriate paper-feed mechanisms. Other names include fan-fold paper, sprocket-feed paper, burst paper, tractor-feed paper, and pin-feed paper. It can be single-ply (usually woodfree uncoated paper) or multi-ply (either with carbon paper between the paper layers, or multiple layers of carbonless copy paper), often described as multipart stationery or forms. Continuous stationery is often used when the final print medium is less critical in terms of the appearance at the edges, and when continuously connected individual sheets are not inconvenient for the application. Individual sheets can be separated at the perforation (leaving a slight serration), and sheets also have edges with punched holes, which also can be removed at the perforation (one typical format).

Derailleur gears

Derailleur gears are a variable-ratio transmission system commonly used on bicycles, consisting of a chain, multiple sprockets of different sizes, and a mechanism to move the chain from one sprocket to another. Although referred to as gears in the bike world, these bicycle gears are technically sprockets since they drive or are driven by a chain, and are not driven by one another.Modern front and rear derailleurs typically consist of a moveable chain-guide that is operated remotely by a Bowden cable attached to a shifter mounted on the down tube, handlebar stem, or handlebar. When a rider operates the lever while pedalling, the change in cable tension moves the chain-guide from side to side, "derailing" the chain onto different sprockets.

For more information about the choice of particular gear ratios and sprocket sizes, see Bicycle gearing.

Film perforations

Film perforations, also known as perfs and sprocket holes, are the holes placed in the film stock during manufacturing and used for transporting (by sprockets and claws) and steadying (by pin registration) the film. Films may have different types of perforations depending on film gauge, film format, and intended usage. Perforations are also used as a standard measuring reference within certain camera systems to refer to the size of the frame.

Some formats are referred to in terms of the ratio "perforations per frame/gauge size" to provide an easy way of denoting size. For instance, 35mm Academy is also known as 4 perf-35mm; VistaVision is 8 perf-35mm; the long-time standard Todd-AO 70 mm film is 5 perf-70mm; and IMAX is 15 perf-70mm. This description does not indicate whether the film transport is horizontal or vertical, but uncertainty is precluded because there are currently no horizontal systems using the same number of perforations on the same gauge as a vertical one.

Fraggle Rock

Fraggle Rock (also known as Jim Henson's Fraggle Rock or Fraggle Rock with Jim Henson's Muppets) is a children's puppet television series about interconnected societies of Muppet creatures, created by Jim Henson.

Fraggle Rock was co-produced by British television company Television South (TVS), the Canadian Broadcasting Corporation, U.S. pay television service Home Box Office and Henson Associates. Unlike Sesame Street, which had been created for a single market and later adapted for international markets, Fraggle Rock was intended from the start to be an international production and the entire show was constructed with this in mind.

Glen Phillips (singer)

Glen Phillips (born December 29, 1970) is an American songwriter, lyricist, singer and guitarist. He is best known as the singer and songwriter of the alternative rock group Toad the Wet Sprocket.

Honda Spocket

The Honda Spocket was a concept car developed by Honda that was displayed at auto shows in 1999 and 2000 but did not enter production.

The Spocket was a convertible with the rear half of the car able to be used for a second row of seats or as a flat floor storage area. It was designed by Honda's California studio, and had a hybrid powertrain with the front wheel driven by a gas engine and the rear wheel by electric motors. It had a wheelbase of 2,750 millimetres (108 in) and a length of 4,270 millimetres (168 in).Honda showed the concept at the 1999 Tokyo Motor Show, the 2000 North American International Auto Show, and the 2000 LA Auto Show, though it did not go into production.

Machine Empire

The Machine Empire is a group of robotic villains in the Power Rangers universe, who first appeared in the television show Power Rangers Zeo and later in Power Rangers in Space and Power Rangers Wild Force.

Roller chain

Roller chain or bush roller chain is the type of chain drive most commonly used for transmission of mechanical power on many kinds of domestic, industrial and agricultural machinery, including conveyors, wire- and tube-drawing machines, printing presses, cars, motorcycles, and bicycles. It consists of a series of short cylindrical rollers held together by side links. It is driven by a toothed wheel called a sprocket. It is a simple, reliable, and efficient means of power transmission.

Though Hans Renold is credited with inventing the roller chain in 1880, sketches by Leonardo da Vinci in the 16th century show a chain with a roller bearing.

Skywalker Sound

Skywalker Sound is the sound effects, sound editing, sound design, sound mixing and music recording division of the Lucasfilm motion picture group. Its main facilities are located at George Lucas's Skywalker Ranch in Lucas Valley, near Nicasio, California.

Sprocket (comics)

Sprocket (Amelia Barnhardt) is a fictional character appearing in American comic books published by Marvel Comics. The character was primarily depicted as a pilot for the superhero team the New Warriors. Her first appearance was in Night Thrasher: Four Control #2. She is African American and is the mother of deceased Redeemers member, Meteorite.

Sprocket Rockets

Sprocket Rockets is a steel roller coaster located at Six Flags Great America in Gurnee, Illinois. This is a junior coaster with a height restriction of only 36 inches (910 mm). It is a Vekoma "roller-skater" model roller coaster. It is located in the Camp Cartoon section of the park, in Yukon Territory, as the headline attraction. It was originally named Spacely's Sprocket Rockets and themed to The Jetsons. It was renamed to Sprocket Rockets in 2018. Sprocket Rockets is the second junior-coaster built at the park. The first, was a Bradley & Kaye Little Dipper named Gulf Coaster, however it only operated in the 1976 season. Fires and other issues forced the park to close it.

Toad the Wet Sprocket

Toad the Wet Sprocket is an American alternative rock band formed in 1986. The band consists of vocalist and guitarist Glen Phillips, guitarist Todd Nichols, bassist Dean Dinning, and drummer Randy Guss. They had chart success in the 1990s with singles which included "Walk on the Ocean", "All I Want", "Something's Always Wrong", "Fall Down", and "Good Intentions". The band broke up in 1998 to pursue other projects but in 2006 began touring the United States as a band again for short run tours each summer in small venues. In December 2010, the band announced their official reunion as a full-time working band and started writing songs for their first studio album of new material since their 1997 Columbia Records release, Coil. Their most recent full-length album, New Constellation, was released on October 15, 2013.


A wrench or spanner is a tool used to provide grip and mechanical advantage in applying torque to turn objects—usually rotary fasteners, such as nuts and bolts—or keep them from turning.

In Commonwealth English (excluding Canada), spanner is the standard term. The most common shapes are called open-ended spanner and ring spanner. The term wrench is generally used for tools that turn non-fastening devices (e.g. tap wrench and pipe wrench), or may be used for a monkey wrench - an adjustable pipe wrench.In North American English, wrench is the standard term. The most common shapes are called open-end wrench and box-end wrench. In American English, spanner refers to a specialised wrench with a series of pins or tabs around the circumference. (These pins or tabs fit into the holes or notches cut into the object to be turned.) In American commerce, such a wrench may be called a spanner wrench to distinguish it from the British sense of spanner.

Higher quality wrenches are typically made from chromium-vanadium alloy tool steels and are often drop-forged. They are frequently chrome-plated to resist corrosion and for ease of cleaning.

Hinged tools, such as pliers or tongs, are not generally considered wrenches in English, but exceptions are the plumber wrench (pipe wrench in British English) and Mole wrench (sometimes Mole grips in British English).

The word can also be used in slang to describe an unexpected obstacle, for example, "He threw a spanner into our plans" (in U.S. English, "monkey wrench").

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