Hello, I have found that the drawings by Mr. K. E. Wilson for the above loco valve gear do not give me the dimensions that I require. While the dimensions of the linkage pivots are not given, the port face openings, eccentric throw and eccentric rod centres are and I have attempted to draw the valve events by CAD so that I completely understand what happens and when. To assist me, I have read Mr. D. Ashton's book and have managed to work out the equivalent eccentric but not the actual. Working out the dimension for this left me struggling. This has not helped me with Mr Ashton's spread sheet either. I have also attempted a Realeaux diagram but the locations of the lap and lead lines on the diagram don't bear any relationship to what I have previously seen. So, I have reached an impasse and can't proceed further with the valve gear. Can anyone can shed some light on this. I would be very grateful for help.

I think the last enquiry on this subject in the forum was round about 2014.

Thank you,

Alastair Parker.