Jak islámští vynálezci nezměnili svět: Difference between revisions

===The crank-shaft===

{{Quote||A device which translates rotary into linear motion and is central to much of the machinery in the modern world, not least the internal combustion engine. One of the most important mechanical inventions in the history of humankind, it was created by an ingenious Muslim engineer called al-Jazari to raise water for irrigation. His 1206 Book of Knowledge of Ingenious Mechanical Devices shows he also invented or refined the use of valves and pistons, devised some of the first mechanical clocks driven by water and weights, and was the father of robotics. Among his 50 other inventions was the combination lock.<ref name="Paul Vallely"></ref>}}

Unfortunately for our ingenious Muslim engineer al-Jazari, the crank-shaft was known to the Chinese of the Han Dynasty.<ref name="crank shaft">[{{Reference archive|1=http://www.trivia-library.com/a/major-engineering-events-in-history-first-use-of-the-crank-834-ad.htm|2=2011-02-07}} Major Engineering Events in History: First Use of the Crank 834 A.D.], Trivia-Library, Inc.</ref> The Han Dynasty lasted from 206 BC to 220 AD. By the 1^st century AD cranks were used on Roman medical devices, but it was not until 834 AD where we find proof of the crank in Europe. A picture in a graphic codex of a man sharpening a sword on a grindstone turned by a crank.<ref name="crank shaft"></ref><ref>[{{Reference archive|1=http://patentpending.blogs.com/patent_pending_blog/2005/04/the_invention_o.html|2=2011-02-07}} The Invention of the Crank, The Crank Powered Bicycle], Patent Pending Blog, April 7, 2005</ref> 206 BC to 834 AD is certainly a lot earlier than when Paul Vallely claims a 12^th century Muslim invented 'one of the most important mechanical inventions in the history of humankind'. What Al-Jazari described was a crank and connecting rod system in a water pump. He incorporated a crankshaft, but it was unnecessarily complex indicating that he did not fully understand the concept of power conversion.<ref> White Jr., Lynn (1962), Medieval Technology and Social Change, Oxford: At the Clarendon Press p.170 ''However, that al-Jazari did not entirely grasp the meaning of the crank for joining reciprocating with rotary motion is shown by his extraordinarily complex pump powered through a cog-wheel mounted eccentrically on its axle.''</ref>