Engineering 1040: Mechanisms & Electric Circuits Fall 2011 Power Transmission Systems: Gear Drives

Gear Terminology

Gear Animation

Factors considered in gear selection Pitch circle diameter Number of teeth Face Width Material used to manufacture the gear Style of hub, bore, etc

A Gear Spur Gear Catalog

Involute Circle The curve most commonly used for gear-tooth profiles is the involute of a circle.

Gear Relationships

Gear Problems (Interference)

Gear Problems (Backlash)

Gear Types (1) Spur Gears – Simplest of the gears – Used to connect parallel shafts – Simple shape – Low cost – No thrust loads from teeth engagement Helical Gears – Smooth operation as it results in gradual gear engagement – Could connect parallel or non parallel shafts – Higher thrust loads from teeth reaction forces

Gear Types (2) Bevel gear – Could be used to connect two shafts that are at an angle – The teeth may be straight or helical – Two gear have conical surfaces Worm & wheel – Very low transmission ratios – High torque transmission – High Friction loses

Gear Types (3) Rack & pinion – Converts the rotational motion into linear motion – Could have straight or bevel teeth – Provides less backlash – Greater feedback