Gears. A gear is a rotating machine part having cut teeth, or cogs, which mesh with another toothed...

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CGT 110S 2013

Gears

Definition

A gear is a rotating machine part having cut teeth, or cogs, which mesh with another toothed part in order to transmit to torque. (Wikipedia)

Two or more gears working in tandem are called a transmission and can produce a mechanical advantage through a gear ratio and thus may be considered a simple machine. (Wikipedia)

Types of Gears

Spur Gear Parallel axis

Helical Gear Parallel axis Helicoid teeth

Skew Gears Axis at right angle and do not intersect

Double Helical Parallel axis Right & Left helical teeth Balances axial thrust forces

Bevel Axis at right angle and intersect Cone Shaped

Gear Types (cont.)

Spiral Bevels A bevel gear with angled spiral teeth

Hypoid Common in differentials Hypoidcycle teeth

Crown (contrate) Type of bevel gear

Worm Axis at right angle and do not intersect One gear is in the form of a worm

Rack and Pinion Rack is straight gear Transmits linear motion

Non-Circular

Gear Terminology

Tooth Profile

Involute Gear

http://www.excelcalcs.com/repository/machines/gears/involute-coords.xls/

Tooth Contact Nomenclature

Tooth Thickness Nomenclature

Pitch Nomenclature