John,john coffin wrote:I do not try to pontificate, but look at all the data that is available, and seek to interpret the data. This is an interesting thread, but many people have not looked at the situation on the GNR during the relevant period. Also many of us may not have looked at the whole picture.
I too, have enjoyed this thread! I'm not sure it's down to continuity through the drawing office as much as the existence of patterns and stores inventory.
I've been looking at both the General Arrangements and the detailed drawings of Ivatt and early Gresley GNR locomotives at York (NRM).
So the Stephenson's link motion in Gresley's J6, D1 and N2 locomotives are piston valve variations on Stirling's Standard Goods locomotive (LNER J3/4). The valve motion is identical (and really, really, not very efficient). Similarly, they have the same motion plates -- more or less -- and the same boiler: LNER #7 and #8.
I've been contemplating writing this up in the GNR News letter under the title of "Standardisation of GNR Locomotives under Ivatt"