Pinwheel calculator
A sprocket is a gear with adjustable number of teeth. It serves primarily as a drive for mechanical calculators. Sprossenradmaschinen in Europe are also referred to as Odhner machines (after Willgodt Theophil Odhner ).
Historical development
From the hand of Gottfried Wilhelm Leibniz (1646-1716) comes the first known design of a sprocket wheel. It is believed that he was considering this sprocket next to the stepped drum later used by him as a drive for its calculators. At his Sprossenradentwurf a tooth had to be raised, who raised all his predecessors with. A corresponding adjustment and the Sprossenradkörper are not present on the drawing.
The Italian astronomer and maths professor Giovanni Poleni (1683-1761) built a wooden abacus with weight drive, which he described in 1709 in " Miscellanea " on page 27. The building, designed by him sprocket worked with nine folding sprouts. With a first, not yet satisfactory working model showed Poleni that his driving principle was compatible. A second machine, worked carefully and built of sterner stuff, he succeeded as desired. This machine could process up to three -digit numbers; it was large and unwieldy; the speed of the gear train was slowed down considerably, and the number transfer should have worked deficient. She was summarize how Bischoff writes, was " an imperfect and useless tool ". However, the publication of the construction and operation of Poleni machine may have served later designers of Sprossenradmaschinen as inspiration.
The Schwabe Anthony Brown (1686-1728) developed in 1727 a sprocket wheel which is in the possession of the Technical Museum in Vienna today. The basic idea of developing a Sprossenradmaschine Brown could have received from Poleni whose machine was described in Theatrum arithmetico - geometricum of Jacob Leupold 1727, a publication that Brown knew probably. In addition to this Sprossenradmaschine Brown also built yet a manipulated segment calculator.
From the years 1841 and 1848 come two circular Sprossenradmaschinen of French physician Didier Roth, who are in possession of the Musée National des Techniques today. An English patent for this invention he received in 1843. Though the machine should have been unreliable, the scion wheels used were mature. Further work by Roth are a classification of computing machines from 1843 and a small, elongated adding machine called " Additionneur " from 1841, which was operated by means of a setting pin.
Another Sprossenradmaschine, which was patented in 1843, comes from the Englishman David Isaac Wertheimber. The sprocket later used by Odhner is very similar Wertheimbers construction. Both adjust the rungs by means of a cam slot. About a realization of Wertheimbers machine is not known.
The Americans Frank Stephen Baldwin (1838-1925) sent on October 5, 1872, a complete description and drawings developed by him Sprossenradmaschine the U.S. Patent Office in order to preserve its rights in this invention. On September 8, 1873 this calculating machine or a development has been filed for patent, which was granted to him on February 2, 1875 # 159 of 244. The rungs are spring-mounted in its construction and be pressed with a semi-circular positioning ring from the Sprossenradkörper. Similar to the later Odhner Abacus the number transfer is realized with the sprocket wheel even when Baldwin. In his patent drawings, a printing unit for these machines is included. By 1874, ten of these " Baldwin Calculators " were prepared: Although designed for series production, never larger quantities were produced. His machine was said to be too expensive and prone to mechanical failure.
Baldwin also dealt with other computing machine designs. Thus was developed by him Monroe calculating machine, a full keyboard - season rolling machine, a commercial success.
Operation
Below the Sprossenradprinzip the Odhner machines is described:
Nine rungs are mounted in radial grooves milled in a Sprossenradkörper. Opposite the Sprossenradkörper a cam slot is introduced into the rotatable collar, which holds the rungs into position. If the collar is rotated clockwise, then the sprouts push successively outwards. A device fitted to the housing of the computing machine scale is divided so that the number of shifted out sprouts is equal to the set number. If now the entire sprocket is rotated by the driving crank, from zero to nine bars engage in a transmission gear.
For orders of transfer are in addition to the nine sprouts two spring-mounted ten rungs on the sprocket that can be pressed by the tens preparation lever of the counter into the processing level.
Appreciation
While four -species machine with relay roller drive apparently could easily develop for the market in the 19th century, took over in the early 20th century machine with sprocket on the European market dominance.
These could be manufactured economically, had compact dimensions and low maintenance were even under harsh conditions. Individual model series were produced in some 10,000 pieces.
At the end of the history of development of mechanical calculating machines they had to compete with the first electronic computers. Here the stepped drum had the advantage that they could be turned quickly by motor power. In contrast, the Sprossenradmaschinen a significantly greater mass had to be moved ( Sprossenradtrommeln weighing up to 2 kg), what engine and mechanics loaded heavily.
Sprossenradmaschinen with engine power
Both season rolling machines as well as those with Pinwheels were early equipped with motors. In Germany, introduced in 1939, the company Carl Walther ( Zella- Mehlis ) successfully model EMKD ago, in which the electric motor drive the Sprossenradtrommel and Zählwerkschlitten. The result was a small semi-automatic in which the Division - automatically expired - by default the values . For multiplication, a selector lever was used, the semi-automatic in working on the second factor digit by digit.
The greatest success with motorized Sprossenradmaschinen had the Swedish company Facit. Your machine also appeared before 1939 in the world market and achieved major sales up in the 70s. Their main advantage was the quiet response and fast adjustment of all values by keys.
The last Sprossenradmaschinen were inexpensive manually operated devices, such as the one shown Brunsviga 13 RM. This was up in the 60s of the 20th century produced in Spain.