BS 4235-1 72nd Edition, February 22, 1972
Metric Keys and Keyways Part 1: Parallel and Taper Keys
Includes all amendments and changes through Reaffirmation Notice , December 1, 2012
Additional Comments: INCLUDES AMENDMENT 1
Published By:British Standards Institution (BSI)
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.