Editing Non-circular gear (section)

{{Short description|Gear in a shape other than a circle}}
[[Image:Non-circular gear.PNG|thumb|Non-circular gear example]]
[[File:Non-circular gear.svg|thumb|Another non-circular gear]]

A '''non-circular gear''' ('''NCG''') is a special [[gear]] design with special characteristics and purpose. While a regular gear is optimized to transmit [[torque]] to another engaged member with minimum noise and wear and with maximum [[Mechanical efficiency|efficiency]], a non-circular gear's main objective might be [[ratio]] variations, axle displacement [[oscillation]]s and more. Common applications include textile machines,<ref name="test1">[http://oktoida.pl/art_2008_3_08.pdf Zarebski I., Salacinski T.: Designing of non-circular gears]</ref> [[potentiometer]]s, CVTs ([[continuously variable transmission]]s),<ref>[http://next-1b.manuf.bme.hu/Laczik/Noncircular.pdf Laczik- Involute Profile of Non-Circular Gears]</ref> window shade panel drives, mechanical presses and high torque hydraulic engines.<ref name="test1" />

A regular gear pair can be represented as two [[circle]]s rolling together without slip. In the case of non-circular gears, those circles are replaced with anything different from a circle. For this reason NCGs in most cases are not round, but round NCGs that look like regular gears are also possible (small ratio variations result from meshing area modifications).

Generally, NCGs should meet all the requirements of regular gearing but in some cases, for example variable [[axle]] distance, could prove impossible to support, and such gears require very tight manufacturing tolerances and assembling problems arise. Because of complicated [[geometry]], NCGs are most likely [[spur gear]]s and [[Molding (process)|molding]] or [[electrical discharge machining]] technology is used instead of generation.