sentences:  Early examples of gears date from the 4th century BC in China (Zhan Guo times – Late East Zhou dynasty), which have been preserved at the Luoyang Museum of Henan Province, China.The earliest preserved gears in Europe were found in the Antikythera mechanism, an example of a very early and intricate geared device, designed to calculate astronomical positions.Its time of construction is now estimated between 150 and 100 BC.