Gears

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Revision as of 14:09, 27 December 2006 by Lynch (talk | contribs) (→‎Spur Gears)
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Types of Gears

Spur Gears

Spur gears.png
Gear-spurgearhead.jpg


Rack and Pinion

Rack and pinion.png


Bevel Gears

Bevel gears.png


Helical Gears

Helical gears.png
Gear-helical2.jpg


Worm Drives

Worm drive.png


Planetary Gears

Gear-planetarystage.jpg
Gear-planetary.jpg


Ball Screw/Lead Screw

Gear-ballscrew.gif
Gear-ballscrew2.jpg

File:Gear-ballscrew.png


Harmonic Drive Gears

Harmonic gears.jpg
Gear-harmonicdrive.gif
Gear-harmonicdrive2aligned.jpg



Gear Geometry

For external spur gears (most common), the gear geometry is as shown in the figure below. The line of action is the line that passes through the intersection of the pitch circles and also tangent to the base circles.

Gear circle geometry.png

Gear Meshing and Forces

Gear meshing results in contacts with normals along the line of action, so the resultant force, is along this line. This results in both tangential and radial forces, and , on the gear pair. When these gears are mounted on a shaft, the radial force causes a bending moment while the tangent force causes both a bending moment and a torque.

Gear triangles.png


References