Editing Gear (section)

===Crossed===
[[File:Engranaje cónico, Nymphenburg, Múnich, Alemania4.JPG|thumb|left|Bevel gear operating a [[lock gate]] ]]
In a ''crossed'' arrangement, the axes of rotation of the two gears are not parallel but cross at an arbitrary angle except zero or 180 degrees.

For best operation, each wheel then must be a [[bevel gear]], whose overall shape is like a slice ([[frustum]]) of a [[cone]] whose apex is the meeting point of the two axes.

Bevel gears with equal numbers of teeth and shaft axes at 90 degrees are called ''miter'' (US) or ''mitre'' (UK) gears.

Independently of the angle between the axes, the larger of two unequal matching bevel gears may be internal or external, depending the desired relative sense of rotation.<ref name="ansiagma"/>

If the two gears are sliced by an imaginary sphere whose center is the point where the two axes cross, each section will remain on the surface of that sphere as the gear rotates, and the section of one gear will interact only with the corresponding section of the other gear.  In this way, a pair of meshed 3D gears can be understood as a stack of nested infinitely thin cup-like gears.