Back in the first half of the 20th Century virtually every technical school had a piece of instructional hardware called a "Steam Instructor", which was basically a steam locomotive valve gear simulator. They were manufactured by several scientific and instructional supply companies in the US. These were usually mounted on a base, with the drivers turned by a hand crank, and you could transit the reverse and watch how the valve gear altered the motion of the valves as the driver was turned. These devices are great collectibles now, very hard to find. I am curious how many of you have seen them, how many systems of valve gear you have seen represented, and also if you have seen any of the ones with multiple drivers (very rare) or were they all singles?
Here is a steam instructor that was recently listed in an eBay auction, sold for $360.99. I am posting this link on Jan 3, 2006. eBay drops the listings after a period of time so if you cannot access it, then they have removed it.
http://cgi.ebay.com/Vintage-Central-Sci ... dZViewItem