This is the difference between the actual position of the output gear and the position it would occupy if the gear drive were perfect. This is usually expressed as angular displacement and may be shown as linear displacement at the pitch point.
Transmission error is the primary excitation of gear noise and is dependent on load.
The main sources of transmission error are:
- Tooth Manufacturing Profile Errors
- Pitch variation
- Profile slope
- Profile fullness
- Lead mismatch
- Static torque induced deflection of the teeth due to tooth compliance
- Static torque induced deflection of gear blank, shafting, bearings or housing
- Deflection due to other operating loads
- Angular misalignment
- Centre to centre distance
See also: Gear Design.