Servicing Documents

On this page are scans of a few documents for servicing the mechanical adding machines.  If you have any more service documents from Bell Punch and Anita I would be delighted to receive a copy or a scan for display here - please get in touch with me.


List of the Wind Springs & Initial Tensions

These tables apparently apply to the springs used in the carry mechanisms of the mechanical adding machines.  John Wolff on his Web Museum site describes the mechanism of the Plus adding machine and refers to the 'spring on the winding gear' of each transfer stage which require pre-loading.  The required pre-loading is listed in these charts for Decimal, £sd currency, and Imperial Unit columns of keys.


Circuit Testing & Fault Finding

This chart appears to be for testing the suppressors on the electric motor-driven mechanical calculators.


Grateful thanks to Ben Stephenson for providing the above copies of the 'List of Wind Springs & Initial Tensions' and the 'Testing & Fault Finding Suppressor Units SAU.255.'  These were used by his grandfather George Alfred Crooks, better known as Jack Crooks, who started at the Bell Punch Co. in 1939 and received a gold pocket watch in 1969 for 30 year's service with the company.  Jack continued with repairing and servicing as the calculator division became Sumlock-Comptometer Ltd., and later for a company in Yorkshire which probably formed after Rockwell broke up and sold off the calculator division in 1976.


Electronic Calculators


The Bell Punch Company & the Development of the Anita Calculator
< Previous page    Next page >

Click here to go to the Vintage Calculators Web Museum

Text & photographs copyright © 2002 - 2023 Nigel Tout, except where noted otherwise.