Mystery steam engine

[chris123]

Jason, could you put a pitch circle through those centre holes and compare with the OD Chris gave in #251? This would help us to be more certain of the eccentric throws (that or throw us into confusion).

I am pretty close to having enough information to reverse engineer the valves.

I shoot another pic

 

[Jasonb]

Charles the size in #251 is the OD of the drive flange and what I scaled the photo to.

The ctrs when measured from that average out around the 1/4" or 6.35mm radius so 1/2" PCD which ties in with post #243 and the much earlier mention of 12mm