Editing Gear (section)

== Non-rigid gears ==

Most gears are ideally rigid bodies which transmit torque and movement through the lever principle and contact forces between the teeth.  Namely, the torque applied to one gear causes it to rotate as rigid body, so that its teeth  push against those of the matched gear, which in turn rotates as a rigid body transmitting the torque to its axle.  Some specialized gear escape this pattern, however.

===Harmonic gear===
[[File:HarmonicDriveAni.gif|thumb|left|Harmonic gearing]]
{{Main|strain wave gearing}}
A ''harmonic gear'' or ''[[strain wave gearing|strain wave gear]]'' is a specialized gearing mechanism often used in industrial [[motion control]], [[robotics]] and [[aerospace]] for its advantages over traditional gearing systems, including lack of backlash, compactness and high gear ratios.

Though the diagram does not demonstrate the correct configuration, it is a "timing gear," conventionally with far more teeth than a traditional gear to ensure a higher degree of precision.
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===Magnetic gear===
{{Main | Magnetic coupling | magnetic gear}}
In a ''magnetic gear'' pair there is no contact between the two members; the torque is instead transmitted through magnetic fields.  The cogs of each gear are constant [[magnet]]s  with periodic alternation of opposite magnetic poles on mating surfaces. Gear components are mounted with a [[Backlash (engineering)|backlash]] capability similar to other mechanical gearings. Although they cannot exert as much force as a traditional gear due to limits on magnetic field strength, such gears work without touching and so are immune to wear, have very low noise, minimal power losses from friction and can slip without damage making them very reliable.<ref>Kravchenko A.I., Bovda A.M. Gear with magnetic couple. Pat. of Ukraine N. 56700 – Bul. N. 2, 2011 – F16H 49/00.</ref> They can be used in configurations that are not possible for gears that must be physically touching and can operate with a non-metallic barrier completely separating the driving force from the load. The [[magnetic coupling]] can transmit force into a [[Hermetic seal|hermetically sealed]] enclosure without using a [[radial shaft seal]], which may leak. Magnetic gears are also used in [[Brushless DC electric motor|brushless motors]] along with [[Electromagnet|electromagnets]] to make the motor spin.