Stanier Princess Royal & Princes Coronation Pacifics

I have added some new photos of Stanier's Princess Royal class in the BR era
This collection features 46200 & 46201 built in 1933

https://railway-photography.smugmug...46204/620046200-The-Princess-Royal-/i-24HS2CQ

Neil

 

I have added 6 new photos to the collection of Stanier Princess Royal pacifics built in 1935, this collection features 46203-46205 which were released to Traffic by July 1935
starting here with
46203 Princess Margaret Rose stored unknown location
https://railway-photography.smugmug...46205-released-to-traffic-July-1935/i-SbPmRtD

Neil

 

58 / 63 = Carnforth

 

Hi does anyone know why Princes Victoria has a a different motion bracket ?

 

The front end of the Princess frames was prone to cracking (all or nearly all eventually had a whole new section welded on) and, perhaps inspired to create room inside for increased bracing together with reducing preparation and maintenance time, it was decided to experiment with operating the inside valves with rocker arms from the outside valves, the drive being from the front of the outside valve chests, which was akin to a mirror image of the GWR arrangement. The Duchesses had already appeared by then and they had a more elegant arrangement with the drive taken from the rear of the outside valve chests and no enormous motion bracket.

I think a problem with the Princess conversion was the relative position of the cylinders (the inside cylinders were a long way ahead of the outside), and the inside and outside cylinders had different inclinations (the inside cylinders were horizontal, the outside 1 in 35). The large motion bracket seems to have been required because of concerns with beefing up the valve gear to drive the two sets of valves, and it is possible that it may have been designed with one eye on providing some frame stiffening. The modification is described in the Wild Swan Locomotive Profile book, which has a (small) copy of drawing D37-15117. (the full size version supplied by the NRM is so large that the lights will dim in the neighbourhood when you open it up)

 

The outside valve gear operated the inside valves by rocking levers so there was more load on the outside valve gear than the other Princess class locos

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