BS 4235-1:1972

This standard BS 4235-1:1972 Specification for metric keys and keyways is classified in these ICS categories:

• 21.120.30 Keys and keyways, splines

This British Standard relates to the following types of keys and keyways with dimensions in millimetres:

1. square parallel,

2. rectangular parallel,

3. square taper, gib-head and plain,

4. rectangular taper, gib-head and plain.

In addition, a fourth class of fit is provided in this British Standard to give an interference fit.

Three classes of fit are provided for the square and rectangular parallel keys and keyways, namely “free”, “normal” and “close”, and the dimensions and tolerances specified are in accordance with ISO Recommendations R 773³⁾ and R 774⁴⁾.

Parallel and taper keys and keyways for shafts of 6 mm to 500 mm diameter. For square and rectangular parallel keys three classes of fit, 'free', 'normal' and 'close', are foreseen.