BS 978-1:1968 PDF

What is BS 978-1 - Involute spur and helical gears specification about?

Fine-pitch gearing usually has teeth of diametral pitch 20 to 200. BS 978 is a British Standard series that discusses specifications for fine pitch gears . BS 978-1 is the first part of the BS 978 multi-series, and relates to involute spur, helical, and crossed helical gears, having diametral pitches finer than 20, in four accuracy grades. Examples of applications are: Class A. Astronomical apparatus and scientific instruments; colour printing machinery; control systems (when multiple trains of gears are involved this grade would generally be used for low-speed components where the effect of positional accuracy is important). Class B. Navigational instruments; high-speed components of control systems where quietness and smooth running are essential; machine tool speed control; photographic instruments. Class C. General-purpose instruments; accounting and calculating machinery; counters; clockwork mechanisms. Class D. Textile machinery; switch operating gear; clockwork mechanisms where accuracy is not the primary consideration.

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