On one side the nut locks the bearing against a shoulder on the spindle to make a 'fixed' bearing...Free play is then adjusted at the other end using the nut and lock nut...When correctly adjusted there should be 1/32nd to 1/16th of an inch movement at the wheel rim..Ian

email (option): ian@wright52.plus.com

Does this illustration help? 44 is the adjusting nut, 45 is its lock nut.BSA supplied special thin spanners for the job. Ron

email (option): ronpier@talk21.com

Once again, thanks both.

email (option): cmmacd@hotmail.co.uk