AC> I have no problem with the dynamics of the lead and trail bogies. The
AC> springing of these could be as good as on a Bo Bo elec or de body. But I 
wo
AC> buy the principle that the main drive wheels of a conventional steamer, 
are
AC> uniformly sharing the burden of the train on- the- move. Because-
AC> 
AC> * The drive wheels and axles have very high mass hence inertia, and will 
mo
AC> slowly respond to the ups and downs of the rail head.
AC> 
AC> * The heavy side rods, pinned to each drive wheel, also restrain any
AC> independence of vertical movement of any single axle as IT passes over a
AC> valley or hill in the rail head.
AC> 
AC> * The springs that serve each axle are much "harder" than those of a
AC> conventional motor bogie. The bogie of today has multiple springs and 
links
AC> Not just one spring per axle box!
AC> 
AC> And, I don't think there is much scope for designing springing 
improvements
AC> into a set of 6, 8 or 10 couple drive wheelsets.
Ahhhhh... hate to butt in, but I am a volunteer with a steam preservation 
trust called "Mainline Steam" here in New Zealand.
All our locos are sprung in some manner or form.... in fact we are just 
replacing the springs on a 2-8-2. 
You think about the riding characteristics of 8 wheels coupled, tottering 
along at 60mph unsprung... the drivers would develop serious faults such as 
cracking and vibration would lead to other egine faults (frame and brass 
problems??).
Granted they are rather stiff... some of our track isnt the best and there is 
a little hump going into one of our shed roads, which is very noticable 
(see-saw effect) when we drive over it. 
We also have a diesel (Drewry built 0-6-0) with coupled wheels, and the 
pings
are on the  outside of the frame....
i dunno.......... 
cheers
Andrew
:)
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