Brunsviga Mechanical Calculator

The machine I purchased was in full working order. Its serial number indicated that it was manufactured around 1954 with a retail price list of DM710.

It is a type of pinwheel calculator which utilises rotating wheels (pinwheels) with adjustable pins to perform calculations. By setting levers to expose a desired number of pins on each wheel, the user can add, subtract, multiply, or divide by turning a crank handle (10). The raised pins engage with a gear driven accumulator register, advancing the display by the selected number.

1. Pinwheels and Setting Levers:

• Each pinwheel has nine retractable pins around its circumference. 
• Setting levers are used to select how many pins are exposed on each wheel. 
• The exposed pins act like gear teeth, advancing the accumulator register when the crank is turned. 

2. Accumulator Register: 

• The accumulator register displays the result of the calculation.
• It’s typically a row of wheels that can be incremented or decremented.

3. Crank Handle and Operation: 

• Turning the crank handle clockwise adds the selected number to the accumulator.
• Turning it counter-clockwise subtracts the number.
• Multiplication and division are performed through repeated additions and subtractions.

4. Carry Mechanisms: 

This ensures the result is displayed accurately, even when a digit position reaches 9 and needs to be “carried” over to the next higher place. Carry mechanisms are used to transfer “carry-overs” from one digit position to the next when performing addition.

An instruction manual for the Model 13RK and 18 RK is available here and a general guide to the use of their earlier machines is available here.

History of the Company

Grimme, Natalis & Co was established in 1871, principally as a manufacturer of sewing machines. It moved into the production and redesign of mechanical calculators after obtaining the rights to the Odhner pinwheel calculator in 1892 which along with the  likes of trhe Arithmometer  led to the commercial success of such devices. They adopted the brand name Brunsviga which is the Latin name for their production site in Braunschweig (Brunswick).

In 1957 Brunsviga entered into an agreement with Olympia Werke AG and was fully absorbed by them in 1959. Production continued but came to an end in the late 1960s. About half a million Brunsviga machines were produced over a period of almost eighty years.

Sources of Information

Brunsviga https://en.wikipedia.org/wiki/Brunsviga
Vintage Calculators Web Museum http://www.vintagecalculators.com/html/brunsviga.html
Jaap’s Mechanical Calculators Page https://www.jaapsch.net/mechcalc/brunsviga.htm
Brunsviga Calculator – shows the internal workings http://www.caffnib.co.uk/calculators/brunsviga.html
John Wolff’s Web Museum provides an overview of the different Brunsviga model types https://www.johnwolff.id.au/calculators/Brunsviga/Brunsviga.htm
Serial numbering https://www.johnwolff.id.au/calculators/Brunsviga/Brunsviga.htm Also in German here with price lists and marketing emblems https://www.rechnerlexikon.de/en/artikel/Brunsviga_Material#Firmeninformationen
Video of one in operation https://www.palladino.com.br/brunsviga-18rk-old-calculator/