Editing Gear (section)

==== Skew axes ====

[[File:Gear-kegelzahnrad.svg|thumb|left|Spiral bevel gears]]
For non-parallel axes with non-straight tooth cuts, the best tooth profile is one of several [[spiral bevel gear]] shapes.  These include Gleason types (circular arc with non-constant tooth depth), Oerlikon and Curvex types (circular arc with constant tooth depth), Klingelnberg Cyclo-Palloid (Epicycloid with constant tooth depth) or Klingelnberg Palloid.<ref name="straightbevel">{{harvnb|McGraw-Hill|2007|p=742}}.</ref> 

The tooth faces in these gear types are not involute cylinders or cones but patches of [[octoidal surface]]s.<ref name=figl2005>{{cite journal | last=Figliolini | first=Giorgio | last2=Angeles | first2=Jorge | title=Algorithms for Involute and Octoidal Bevel-Gear Generation | journal=Journal of Mechanical Design | volume=127 | issue=4 | date=2005-07-01 | issn=1050-0472 | doi=10.1115/1.1900147 | pages=664–672}}</ref> Manufacturing such tooth faces may require a 5-axis [[milling machine]].

Spiral bevel gears have the same advantages and disadvantages relative to their straight-cut cousins as helical gears do to spur gears, such as lower noise and vibration.<ref name="straightbevel">{{harvnb|McGraw-Hill|2007|p=742}}.</ref>   Simplified calculated bevel gears on the basis of an equivalent cylindrical gear in normal section with an involute tooth form show a deviant tooth form with reduced tooth strength by 10-28% without offset and 45% with offset.<ref>Diss. Hünecke, TU Dresden</ref>

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