Plus & Sumlock Mechanical Calculators
PLUS 509/S Sterling Currency Calculator

Plus model 509/S

Sterling currency adder.

This has a direct action keyboard of the "comptometer" type.

It is a model 509/S where the 5 denotes the abbreviated keyboard (keys up to 5), the 09 denotes the 9 columns of keys, and the S denotes a Sterling currency version.

The calculator in the photograph above displays the total:
£1,234,567 17s 11d.

230 x 190 x 124 mm (9" x 7.5" x 4.9").

This casing style was replaced by a more modern version in 1958.
Made by Bell Punch Co. Ltd. in Britain, distributed by Sumlock Ltd.

The machine illustrated has serial number 509/S/95.899.

With the cover removed.

With the cover removed.


Rear of the calculator.


This older style casing has the maker's badge on the back, secured in a recess with adhesive. Often the adhesive weakens and the badge falls off and is missing.

Click here to go to the Vintage Calculators Web Museum

Text & photographs copyright © 2002 - 2017 Nigel Tout, except where noted otherwise.