couldn't decide where to put this so if it needs to be moved--OK.
While looking for something for Gerhard, I came across this site with all sorts of interesting steam stuff including plans for an oscillating engine that are free  for personal use but copyrighted for any other use. Have a look, you'll likely find something of interest.
Here are a bunch of links to save you some time
http://www.classicsteamengineering.com/index.php?topic=468.0
condesing steam engine drawings 1920's
http://www.classicsteamengineering.com/index.php?topic=70.0
http://www.classicsteamengineering.com/index.php?PHPSESSID=8o61nf9l2vehecb5c1hu0amsc0&#12
http://www.classicsteamengineering.com/index.php?board=296.0
and here is a youtube of a sidelever engine the plans of which are what I am looking for for Gerhard. Does anyone have Model Engineering 14-27 jan., 2011-article by Modens Kilde and plans for side lever engine?
and here is an image of an engine featured in one of the links

Hi Dave
Really good stuff, this site is saved as one of my favorits! Thank you 
Regards
Gerhard