Sprocket

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16T type sprocket
Do: Sprocket diameter
Dp: Pitch diameter

A sprocket and roller chain

A sprocket is a profiled wheel with teeth that meshes with a chain, track or other perforated or indented material. It is distinguished from a gear in that sprockets are never meshed together directly, and from a pulley by not usually having a flange at each side.

Sprockets are used in bicycles, motorcycles, cars, tanks, 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.

[edit] Cycles

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 10-speed bicycle, by providing two different - sized driving sprockets and five different-sized driven sprockets, allows up to ten different gear ratios. The resulting lower gear ratios make the bike easier to pedal up hills while the higher gear ratios make the bike faster to pedal on flat roads. 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.

[edit] Tracked vehicles

A tank sprocket

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.

[edit] Film and paper

Sprockets are used in the film transport mechanisms of movie projectors and movie cameras. 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.

[edit] See also

• Toothed belt

v • d • e Gears Gear systems Spur gear systems • Worm gear • Rack and pinion • Epicyclic (planetary) gearing • Sun and planet gear • Harmonic drive • Cycloidal drive • Non-circular gear Gear shapes Spur gear • Bevel gear • Helical gear • Hypoid gear Geartooth profiles Involute • Cycloid Gear mechanics Transmission • Differential • Gear coupling • Gear train • Bicycle gearing • Continuously variable transmission • Offset (gears) Examples Freewheel In Bicycles: Cassette (bicycle part) • Derailleur gears • Fixed-gear bicycle • Hub gear • Shaft-driven bicycle • Sprocket See also Ball screw • Leadscrew • Jackscrew • Belt drive • Chain drive • Gear manufacturing