What is BS 721-1 - Worm gearing specification about?  
Worm gears provide high reduction ratios and correspondingly high torque multiplication. BS 721-1 is a British Standard that discusses the specification for worm gearing.
BS 721-1 is the first part of the BS 721 multi-series, and applies to worm gearing and comprises cylindrical involute helicoid worms and worm wheels conjugate thereto, the dimensions of which are expressed in inches, Four classes of gears are provided which are related to function and precision. The range of modules is given in convenient steps from 0.052 to 1.
Note: BS 721-1 does not refer to pairs of cylindrical gears connecting non-parallel axes known as crossed helical gears.
Who is BS 721-1 - Worm gearing specification for? 
BS 721-1 on worm gearing specification is useful for: 
- The manufacturing industry
- Manufacturers and suppliers of worm gears
- Product design engineers/innovation teams
- Quality control personnel
- Mechanical engineers
- The automobile industry
- Agencies involved in worm gears
Why should you use BS 721-1 - Worm gearing specification?  
A worm gear is a gear consisting of a shaft with a spiral thread that engages with and drives a toothed wheel.
BS 721-1 walks you through aspects such as general Information on worm gear elements, notation, and the form of threads and teeth. BS 721-1 also provides guidance on formulae for calculation of dimensions of worm gears.
Additional aspects that are discussed in BS 721-1 include the general system of worm gear design tables, dimensions of standard worms and wheels, tolerances, working temperature, efficiency and lubrication, and irreversibility. 
With BS 721-1 you can also determine the static and fatigue strength of worm gears. BS 721-1 helps in improving the quality and strength of worm gears. BS 721-1 contributes towards the longevity of worm gears.
