I just thought it might be of interest, probably not reversable though...
http://cgi.ebay.co.uk/Small-model-live-steam-vertical-twin-overhead-valve-eng_W0QQitemZ270255772927QQcmdZViewItem?hash=item270255772927

I'm certainly no expert on steam engines (exactly the opposite in fact!), but I cannot see meccano chain and sprockets being very good for accurate valve timing!

Regards
Eddy

I had an email conversation with a chappie about this engine and he asked me how it worked. From a picture it is very difficult to work out, but I think I had it cracked on how it worked. It definitely wasn't worth what it went for, as if it did work on the principle I came up with, it would only just about have enough power to turn itself over.

John

My guess is the top shaft is hollow and has holes drilled, which will match ports in the top. Definitely was over priced. Looks like it may have been a shop project at school, and probably only turned over on shop air unregulated. I vaguely remmember seeing something similar in a shop project book when I was in grade school(That's a real long time back).
Regards,
Gerald

another unusual (over-complicated?) design, seems to have quite a good low speed ability though - http://www.youtube.com/watch?v=0q9CgUW-O7g

Hi PD's ...& yes Mick it is only a model...........but  ...I would not like to be the first bearing in the output shaft with that amount of shaft wobble   .....Derek

But isn't it just adorable,with all those bits moving