In the early 1930s, the Soviet Union introduced two modern, large locomotive classes. The 'FDp' was a 2-8-4 intended for passenger working with 1850 m.m. diameter coupled wheels whilst the 'FD' was generally similar but arranged as a 2-10-2 with smaller coupled wheels intended for freight duties.
I saw the only surviving 'FDp', number 578, in Ukraine in 2005 when I went with my friend Mike on a steam driving holiday which is briefly described here and with a set of pictures (including the 'FDp') here.
It was to be 2012 and my Trans-Siberian trip before I saw an 'FD20' class, number 588, in the Rolling Stock Museum at Novosibirsk. Pictures of this locomotive are in the set Loco-profile: Russian 'FD20' class 2-10-2.
All the pictures from the Rolling Stock Museum at Novosibirsk are here.
For technical specifications, refer to Reference 1.
References:
Reference 1: 'Soviet Locomotive Types - The Union Legacy' by A J Heywood & I D C Button (Frank Stenvalls Forlag) ISBN 0-9525202-0-6.
