The EOS calculator is used in a similar way to a standard pinwheel machine, except that the carriage contains the input register instead of the main register and counter. So instead of moving the output register to the right you move the input register to the left. It uses an oscillating segment mechanism.
It has a capacity of 9 digits of input, an 8-digit counter, and a 13-digit register. The counter does not have a carry mechanism, and displays red digits for subtraction/division. On the right hand side of the machine are a main crank, a small clearing crank for the counter, a clearing knob for the main register (the knob replaces the original small clearing crank), and a knob for selecting whether to clear the input automatically for addition. Note that the automatic clearing should not be used with subtraction as it clears the input before the subtraction can be executed.
The serial numbers for the EOS started at 20000, and my machine has serial number 20994. There seem to be no machines with a higher number so this is one of the last ones ever made, no more than about 1000 were produced.
The oscillating segment mechanism is controlled via various cams on the main axle that is turned by the crank. During an addition, the following steps are performed:
During subtraction the crank is turned in the opposite direction so most of the steps above are performed in reverse and in opposite order, except that the carries are performed at a different moment through a different set up bulges on the carry drum.
If automatic input clearing is active, the input will be cleared in step 1 so that step 3 then has no effect. The automatic input clearing should therefore never be used with subtraction.
In this video I demonstrate the EOS calculator.
In this video I show the mechanism of the EOS calculator.
Most of the information in this section was taken from an article written and researched by Martin Reese, that was reprinted in his 2002 book "Neue Blicke auf alte Maschinen". That article is available at Rechenmaschinen-illustrated (PDF, 2MB).
Albert Schubode worked at Grimme Natalis on Brunsviga calculators. He left in 1922 and moved to Peine, a town halfway between Brunswick and Hannover. There he co-founded "Hannovera-Rechenmaschinenfabrik, Oventrop, Heutelbeck und Co.". The other founders had experience in manufacturing, metalwork, and marketing, while Schubode was the designer. Production of pinwheel machines started in 1923.
The model A was a standard sized pinwheel machine, capacity 9×8×13, with a carry mechanism in the revolution counter. Model AK was the same but without carry in the counter. The B and BK models were machines with and extra large capacity, namely 20×12×20.
Grimme Natalis aggressively enforced their patent rights, especially relating to the carry mechanism in the counter. This together with the worsening inflationary economy soon made production of pinwheel machines very difficult. To overcome these troubles, Schubode designed a new mechanism that was easier to make. Most parts were stamped metal or cast iron rather than machined parts, and the toothed segment mechanism did not violate the Grimme Natalis patents. This was commercially released in 1926 as the models C and CK.
The model CK did not ease the financial difficulties of the Hannovera company, so further avenues had to be explored. The model CK was used as the basis for a cash register, a till. Despite the moderate success of this cash register, the company was still in financial trouble and ceased trading after about 1929.
Emil Bauer, who sold the Hannovera cash registers in North Germany, bought the remains of the Hannovera company, and set up a new production line in Berlin. From 1933 till 1971 he manufactured Hannovera cash registers, making about 16600 units in that time.
The EOS calculator was made by the EOS-Genossenschaft für Fabrikation und Vertrieb von Rechenmaschinen, based in Zürich at Albisstraße 2. Not much is known about this company. The EOS was virtually identical to the Hannovera CK, except that the case has an EOS logo. As with the CK, two carriage shifting mechanisms were available, a simple crank or a more complicated mechanism with a knob. The EOS was made purely for the Swiss market.
Martin Reese speculated that the EOS was made from a batch of Hannovera CK parts that was bought when Hannovera folded in 1929. This cannot be true however since the advertisements for the EOS calculator already appeared in 1927, and the company was present at the Schweizer Mustermesse in 1926. It therefore seems more likely that the EOS was a licensed version of the CK. It is not clear whether any Hannovera parts were used, especially at first, or whether it was completely manufactured by EOS. The case of the calculator states that it was manufactured in Switzerland so at least some of it was made there.
The EOS was manufactured until at least 1929, and probably for a few years after that. In 1934 the company was bought by H.W. Egli AG in order to expand the production capacity for the MADAS Portable calculator.
|1923-1925||A, AK, B, BK||Hannovera, Peine||1001-5000||4000|
|1926||C, CK||Hannovera, Peine||10000-12000||2000|
|1927-1929||C, CK||Hannovera, Peine||12000-18000||1000?|
|1933-1971||Registers||Emil Bauer, Berlin||30000-46600||16600|
Here is a list of all the EOS machines I have been able to find online. Those that use a crank for
the carriage shift are marked with an asterisk.
20011; 20185; 20080*; 20662*; 20772; 20994; 20???*.
The 1925 book Die Rechenmaschinen by Ernst Martin describes the Hannovera machines, including an early version of the model CK that had not been released yet at that time.
Here are some adverts for the Hannovera CK and the EOS that I found in various online newspaper archives.
Here are some other patents relating to the Hannovera.
|Patent||Filing date||Publish date||Name||Description|
|DE 372,138||15-01-1922||24-03-1923||Albert Schubode||Carry mechanism|
|DE 375,752||15-03-1922||17-05-1923||Albert Schubode||Carriage shift mechanism|
|DE 381,619||29-06-1922||22-09-1923||Albert Schubode||Carriage shift mechanism|
|DE 383,977||29-06-1922||20-10-1923||Albert Schubode||Carriage shift mechanism|
|DE 385,978||25-02-1923||29-11-1923||Hannovera Rechenmaschinenfabrik||Split register|
|DE 394,333||12-09-1922||17-04-1924||Hannovera Rechenmaschinenfabrik||Split register with overflow bell|
|DE 395,176||15-01-1922||15-05-1924||Hannovera Rechenmaschinenfabrik||Oscillating segment mechanism, prototype
See also: FR 560,914; GB 229,302; US 1,690,651
|DE 398,944||09-06-1923||16-06-1924||Hannovera Rechenmaschinenfabrik||?|
|DE 401,647||09-11-1923||08-09-1924||Hannovera Rechenmaschinenfabrik||Counter with carry|
|DE 404,885||14-03-1923||23-10-1924||Hannovera Rechenmaschinenfabrik||Double register|
|DE 405,335||31-01-1924||31-10-1924||Hannovera Rechenmaschinenfabrik||Carry mechanism|
|DE 405,412||26-07-1923||05-11-1924||Hannovera Rechenmaschinenfabrik||Keyboard mechanism|
|DE 407,509||09-02-1924||23-12-1924||Hannovera Rechenmaschinenfabrik||Counter with carry|
|DE 407,511||18-03-1924||22-12-1924||Hannovera Rechenmaschinenfabrik||Oscillating segment mechanism, prototype|
|DE 409,433||29-01-1924||05-02-1925||Hannovera Rechenmaschinenfabrik||Overthrow prevention|
|DE 413,824||18-11-1923||18-05-1925||Hannovera Rechenmaschinenfabrik||Counter with carry|
|DE 416,567||12-02-1924||23-07-1925||Hannovera Rechenmaschinenfabrik||Carry mechanism (CK)
See also: CH 115,149; US 1,693,766.
|DE 428,501||19-02-1925||06-05-1926||Hannovera Rechenmaschinenfabrik||Counter with carry|
|DE 447,773||06-07-1926||02-08-1927||Hannovera Rechenmaschinenfabrik||Counter clearing mechanism|
Rechner Lexicon has pages about the
Hannovera CK and the
Rechenmaschinen-Illustrated has pictures of Hannovera calculators and the EOS. It also has the Martin Reese article (2MB pdf).
Cris Vande Velde has a nice Hannovera CK.
Rechnen Ohne Strom has an EOS calculator.
The Arithmeum has a Hannovera CK and an EOS.
Milestones in Analog and Digital Computing by Herbert E. Bruderer shows that the EOS Genossenschaft was present at the Schweizer Mustermesse from 1926 to 1928.
© Copyright 2021 Jaap Scherphuis, mechcalc a t jaapsch d o t net.