The Kuhrt A2 is a large calculator with a full keyboard, made between 1924 and 1927. It has 8 columns of keys with an input display register above it. The carriage has an 13-digit output register and an 8-digit counter. The crank is a the front right, and is turned clockwise for addition and anti-clockwise for subtraction. There are two small levers on the right of the carriage with which the main register and counter are cleared. The small red lever to the right of the keyboard can be pulled forward to clear the keyboard. It can be shifted to the right for addition / subtraction, as then every turn of the crank automatically clears the keyboard. If the lever is shifted left, then the keyboard is not cleared and this is used for multiplication or division.
The Kuhrt machine uses a unique pinwheel mechanism. There is a pinwheel behind each of the register's number wheels, but whereas the standard Odhner pinwheel has pins that extend and retract, the pinwheels in this machine shift sideways in order to interact with the number wheel.
Pressing a key places a cam in the right position to deflect the appropriate number of pins to the left. The deflected/activated pins remain in position for about half a rotation of the pinwheel, during which time they advance the associated number wheel. As the wheel rotates further, the deflected pins are reset, while a separate springloaded pin handles any carry operation. Those carry pins work in the same way as on an Odhner pinwheel machine, and are arranged similarly in a helical shape so that carries are performed from right to left in the register.
The serial number of this machine is 159, which can be found on the rear of the carriage when it is shifted right, and on a few internal parts of the machine.
In about 1919 Ernst Kuhrt invented a new calculator which was fully automatic and had a printing mechanism. To manufacture this machine he eventually turned to Wilhelm Morell AG in Leipzig.
Wilhelm Morell (full name Paul Richard Wilhelm Morell) had made a name for himself as a manufacturer of tachometers and speedometers. These had become widely used in cars and planes, but also in other machinery. In July 1921 his company became an Aktiengesellschaft, a public limited company. It seems that in 1923 the company was beginning to transform itself to making calculators, and in 1924 they first exhibited at the Leipzig spring fair. This was probably the Kuhrt US, the fully automatic printing calculator, but soon enough they also had simpler and cheaper models A and AB available.
The calculators were manufactured by Deutsche Rechenmaschinen Werke AG. This was probably the new name of Wilhelm Morell AG, though it may be a daughter company. My machine also has the name Wales Adding Machine Co, Schaffhouse on the keyboard plate, which is a Swiss company that was founded in 1924 to import and distribute adding machines by Wales as well as other manufacturers. It seems that the Kuhrt machines were commercially not very successful. Despite investment from Wales, the company only lasted a few years. In 1927 it was liquidated, and Grimme Natalis (Brunsviga) bought the intellectual property. Brunsviga did not continue production, and probably only bought it in order to keep it out of the hands of competitors.
It seems that only about 2500 machines were made in total of the three main models, and in the table below I have included all machines that I have found online.
| Model | Description | ||
|---|---|---|---|
| A | Base model; manual or electric | ||
| Variant | Capacity | Known serial numbers | |
| A2 | 8×8×13 | 159, 654, 1561, 2527, unknown | |
| A3 | 8×8×16 | 1790 | |
| A4 | 10×10×13 | ||
| A5 | 10×10×16 | 1584, 1923, unknown | |
| Model | Description | ||
| AB | Like model A but with back transfer; manual or electric | ||
| Variant | Capacity | Known serial numbers | |
| AB2 | 8×8×13 | 1924 | |
| AB3 | 8×8×16 | 1721, 1790 | |
| AB4 | 10×10×13 | ||
| AB5 | 10×10×16 | ||
| Model | Description | ||
| US | Very large capacity electric machine with automatic direct multiplication, automatic division, memory register, back transfer, printing, negative totals. | ||
| Variant | Capacity | Known serial numbers | |
| US | 16×10×18 | 9 | |
Here are a few items related to Wilhelm Morell, up to the point the company started making the Kuhrt calculator.
These items relate directly to the Kuhrt calculator, and includes the extensive entry in Ernst Martin's Die Rechenmaschinen.
These last items show the decline of the company and its liquidation.
| Patent | Filing date | Publish date | Name | Description |
|---|---|---|---|---|
| DE 344,259 | 14-09-1919 | 18-11-1921 | Wilhelm Morell AG; Ernst Kuhrt | Calculator
See also: AT 90,436 B, CH 96,493, FR 523,565, GB 150,970, US 1,792,644. |
| DE 344,260 | 14-09-1919 | 18-11-1921 | Ernst Kuhrt | Key locking and input display |
| DE 355,199 | 13-09-1920 | 23-06-1922 | Ernst Kuhrt | Printing mechanism
See also: CH 96,494 GB 175,581 US 1,776,076 |
| DE 378,077 | 18-03-1922 | 05-07-1923 | Wilhelm Morell AG; Ernst Kuhrt | Multiple registers
See also: AT 94,774 B CH 102,571 US 1,798,329 |
| DE 400,159 | 12-08-1922 | 02-08-1924 | Wilhelm Morell AG | Carry mechanism |
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