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

Plus model 509/S

This is a direct action keyboard calculator of the "comptometer" type. It has an abbreviated keyboard (keys up to 5) and is designed for Sterling currency calculations.

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

Rear of the calculator.
Badge

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.
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Operating a Comptometer
Old Sterling Currency, £sd
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Plus & Sumlock Mechanical Calculators
Introduction
Plus Adder B
Plus Adder D
Plus Adder S
Plus Adder SJ
Plus Adder ST
London Computator 509/S
London Computator 912/S
Plus 506/D
Plus 506/F
Plus 506/T
Plus 509/D
Plus 509/F
Plus 509/S
PLUS 509/SP Weight Calculator
PLUS 509/T Time Calculator
PLUS 509/Y Weight Calculator
Plus 512/S
Sumlock 912/F
Sumlock 912/S
Sumlock 912/Y Weight Calculator
Sumlock 913/S with Certopost
Sumlomatic
Sumlock Comptometer 993m
Sumlock Comptometer 993s

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Text & photographs copyright © 2002 - 2010 Nigel Tout, except where noted otherwise.