treadmill
A treadmill (also Tretrad or impeller ) is a since the Roman Empire to the Modern the used drive for mills and in particular for lifting devices ( cranes ). It works on the principle of the corrugated gear and uses the physical strength of humans or animals, as do other Göpel (umbrella term).
Today the word treadmill is used in a figurative sense for a monotonous activity or daily routine.
Construction and operation
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The core of a treadmill is one or more (usually two) tall wooden treadwheels ("Fabricae pedales", footworks, running wheels, diameter of 3 m to 5 m) with usually eight wooden spokes on each side. The wheels were on a heavy horizontal timber shaft mounted at the medieval Tretkränen with rotating roof in a square wooden structure as cycle "carrier" or detached wheel bearings rested (in Roman cranes and as a permanently mounted lifting device). In mills (grain mills, pump mills, etc.), the horizontal drive axle was connected to the grinder or pumping mechanism; in the case of lifting devices, a pedal device sat on the axle , either in its extension or between the treadmills . In the simplest case, the pedal device was a section on the axle with limiting rings. The pedaling device took on rope or chain . In the treadmills, the inner surface (running surface) of which was provided with anti-slip tread strips, the runners, treadmills or winch drivers (also called winch drivers, in cranes also crane servants) ran and set the mechanism in motion in the desired direction. There were also designs similar to a water wheel , in which people walked outside on shovel-like stepping boards.
On medieval construction sites which were wind servants (to the 18th century were widespread Tretradantriebe) as high- to highest-paid workers. The job was arduous, extremely strenuous and dangerous in lifting equipment. Holding the loads was difficult because the running wheels could not be secured in order to keep the load level during the turning process. Discharging the loads was also dangerous, because the weight of the load could make itself independent and cause the men on the bikes to “spin” and “skid” (idiom): there were sometimes serious and fatal accidents. To lift a load to a height of 4 m, the winch men had to cover about 56 m of running distance in the running wheels (depending on the axle and wheel diameter: with a 4 m wheel diameter and 0.4 m axle diameter, one wheel revolution corresponds to 12.56 m running distance and 1 , 26 m winding length (= lifting height), that is 50.24 m running distance and 5 m lifting). This meant a total distance of around 132 to 140 m for a complete lifting and lowering process. In such an activity everyone had to be able to rely on the other. A lot of experience and stamina were required in order to successfully manage the hard work in piecework (calculated after the load has been discharged according to a list of charges by the crane master). Between 15 and more than 20 men worked in and on a medieval loading crane. Some of them were organized in the “Aufläder Guild”, the original word for crane loading.
Areas of application
In the shipping industry , the harbor cranes , which had been in use since the Middle Ages, were usually operated with double wheels attached to both sides of a rotating tower to save time. These tower cranes were built either from wood or stone and could handle loads of up to 2.5 tons when loading. It is estimated that around 80 cranes were in use at 32 crane locations on the Rhine with tributaries, in the entire German-speaking area around twice as many.
The use of treadles was also widespread in the operation of mills and in the construction of large buildings, especially the medieval cathedrals, where treadle cranes were integrated into the roof structure as single or double wheels. In Freiburg Minster , Gmünder Münster , Strasbourg Minster , in St. Marien and St.Nikolai Stralsund as well as in the Abbey of Mont-Saint-Michel , these are still present. To 1868 was on the hitherto unfinished south tower of Cologne Cathedral a driven by treadmills Crane ( Domkran ) from the 15th century.
In the early 19th century, convicts had to work in the treadmills in the British colonies . Two such mills, cynically referred to as " dancing academies ", were used in Sydney from 1823 to drive flour mills . As these mills made great profits, six more were put into operation. The working time was up to twelve hours a day, the performance was related to the steam engine and given as 70 watts per worker. From 1850 it is reported that 28 convicts refused to work in the treadmill and preferred death by hanging . Women also had to work in the treadmills, and pregnancy was not taken into account.
Treadmill in the figurative sense
The treadmill, with the word treadmill as a general term, led to the term "treadmill" for a strenuous, uniform activity. The metaphor of the hamster wheel is also used synonymously .
In culture
In a court case, Oscar Wilde was shown to have had contact with male prostitutes , so that in 1895 the judge was able to convict him of two years of forced labor for “immoral acts”. At HM Prison Reading , Wilde was forced to do six hours a day in a treadmill. In his poetry work The Ballad of Reading Gaol he accuses, among other things, the prison conditions in Reading . The film Oscar Wilde shows how prisoners had to work in treadmills in Victorian prisons.
Individual evidence
- ^ A paradoxical genius , sueddeutsche.de, accessed on June 16, 2018
- ↑ And dark detention for those who speak , nzz.ch, accessed on June 16, 2018
literature
- Cotterell, Brian & Kamminga, Johan: Mechanics of Pre-industrial Technology . Cambridge University Press, Cambridge 1992, ISBN 0-521-42871-8
- Dienel, Hans-Liudger / Meighörner, Wolfgang: The Tretradkran . Publication by the Deutsches Museum (history of technology series), 2nd edition, Munich 1997
- Matthies, Andrea: Medieval Treadwheels. Artists' Views of Building Construction. In: Technology and Culture, Vol. 33, No. 3 (July 1992), pp. 510-547
Web links
- The old crane , lueneburg-erleben.de
- Leonhardskirche (Basel) , e-pics.ethz.ch