Valvegear

[davidimurray]

Hi Everybody

I'm currently in the process of designing the valvegear for my 3 1/2" gauge NG15 loco. I've scaled down the original valvegear and then popped the values into Allan Wallace's valvegear simulator. With I bit of tweaking here and there, I've got the ' family' of indicator diagrams shown below.

Any thoughts, good bad or ugly. Is there excessive compression when the gear is notched up? There is a slight bit of lost symmetry due to the valve events not being quite central but this can be sorted when the valves are fitted to the rods.



I look forward to the replies !

Cheers

Dave

[GeorgeRay]

Silly question but why don't all the diagrams have 100 % stroke, or have you found a means of shortening piston stroke as cut off is reduced. The problem is that indicator diagrams are only theoretical and dont actually give any real indication of the actual pressure diagramms. I think you really need to know what the valve movements are, to have a better idea if your design is likely to be successful