I am doing a course on use of Control Theory in Mechanical engineering. One of the mathematical models in the text book is http://www.flickr.com/photos/66943862@N06/6292168944/lightbox/" [Broken] This is a torque transmitted by a gear train. This also has springs & dashpots on both sites. I am trying to look for a real life system which looks like this - i.e. some system where torque is transmitted via a Gear train and there is spring & damping. Is there such a real life example?