Slip eccentric and Bilgram's diagram

[Dan Rowe]

Hi all,
I have started a valve gear discussion on the 7/8ths scale group, where I am the moderator and I know how to add graphics and photos. I am attempting to show how to design a slip eccentric reverse gear using Kozo's first Shay as the example engine.

I will take this example all the way through to drawing a sine diagram for the valve. This I will use to compare with the sine diagram that Dockstader's program will generate using Kozo's first Shay. This way we will be able to see how a single eccentric design compares to Stephenson reverse gear.

The thread I am writing will be a future article in "Steam in the Garden" so if anyone is interested in valve gears or can help me improve my text or coverage of Bilgram's valve gear diagram and slip eccentric the input would be appreciated.

Link to valve gear simulators:
www.colinusher.info/Software/valve%20gear.html
Link to discussion on 7/8ths scale forum:
www.7-8ths.info/index.php?topic=16679520.0
Audels Engineers and Mechanics Guide 1 for Bilgram refference:
books.google.com/books?id=_IdIAAAAMAAJ&printsec=frontcover&dq=editions:0WzMMvNDSi7EEAVVc8#PPA213,M1

You do not have to be a member to read the topic and view the graphics. The links will not show to nonmembers but I just gave them here.
Cheers Dan

[Bill Holland]

Dan, thank you for those informative links

[Dan Rowe]

Hi all,
Dockstader's valve gear programs now include slip eccentric. This is very handy as the only error in slip eccentric gear is the eccentricity of the connecting and eccentric rods.

This allows us to construct an oval diagram with only those two sources of error. The reason this is so handy is it can be used as a goal post for Stephenson valve gear design. If changes are made to a Stephenson design and the oval diagram looks more like the slip eccentric oval diagram then improvements have been made.

For more information see:
www.7-8ths.info/index.php?topic=16679520.0

I used Kozo's first Shay design to prove my points, and the information to run that design with either slip eccentric or Stephenson gear is presented.

Cheers Dan