One of the locomotives at Kitsap Live Steamers had Southern valve gear. During operation it experienced changing valve timing due to the suspension issues noted above. I suspect the main driver had full movement of vertical throw, exacerbating the situation.Bill Shields wrote:that's cool. I have a working example of the gear that I am going to use -> but because of some minor differences between center of piston and valve seat surface, have to re-design the gear.
One thing that I have learned is that as the suspension moves up and down, so does the valve timing. I had not thought about this (previously) because the engine that I am using as my example, runs perfectly square all the time - fwd or back, any cut off.
What I found after close examination, is that the main driver suspension sits on an upper stop so that the only possible travel is DOWN in the even of something really serious happening on the track. Otherwise, the main drivers just sit there and the rest of the engine works around them, keeping the valve events really square."
The owner replaced the valve gear with Walshearts gear, gorgeously made, and solved the changing timing issues.
Interesting to me the different gear designs, and resulting operational variables. Humans are creative.
~RN