Brunsviga Trinks-Triplex Calculating Machine

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Franz Trinks led development of the Brunsviga calculating machine from the 1890s, steadily patenting improvements in Odhner’s original design. The Trinks Triplex was one of these.
The pinwheel lever-set non-printing machine has a black metal housing, a steel mechanism, and 20 levers that are used to set numbers. A steel crank with a wooden handle that extends from the right side of the machine is rotated backward (clockwise) for addition and multiplication and forward (counterclockwise) for subtraction and division.
At the front of the machine is a movable carriage with 20 windows that show dials of the result register on the right and 12 windows for the revolution register on the left. This revolution register has no carry. The digits on the revolution register dials are white for additions and red for subtractions. At the back of the machine is a second revolution register with 12 windows. There is a carry in this register.
The revolution register and the result register have sliding decimal markers. Pushing back a button at the front of the machine releases the carriage for shifting. Rotating wing nuts at the ends of the carriage zeros the registers on it. Rotating appropriate wing nuts on the left side of the machine zeros the pinwheels and the second revolution register. A bell on the left end of the carriage rings when the result passes through zero.
The case consists of a wooden base with a handle in the side, and a curved metal cover painted black.
As the name suggests, the Trinks Triplex was three machines in one. It could be used simply to generate results of up to 20 digits. The mechanism also includes a split device for the result register, which allows one to solve two problems simultaneously. Finally, one can figure the sub-result of a problem in one section and accumulate the total result in the second, showing all factors on the machine at the conclusion.
J. H. McCarthy, The American Digest of Business Machines, Chicago: American Exchange Service, 1924, p. 70.
E. M. Horsburgh, ed., Handbook of the Napier Tercentenary Celebration of Modern Instruments and Methods of Calculation, Edinburgh: G. Bell & Sons, 1914, pp. 84–91.
Currently not on view
date made
Grimme, Natalis & Co.
place made
Deutschland: Niedersachsen, Braunschweig
Physical Description
steel (overall material)
wood (overall material)
plastic (overall material)
overall: 19.3 cm x 43.5 cm x 29.5 cm; 7 19/32 in x 17 1/8 in x 11 5/8 in
ID Number
accession number
catalog number
maker number
Credit Line
Gift of University of Michigan, School of Public Health
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Calculating Machines
Data Source
National Museum of American History


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