64XX / 74XX Bunker / cab joints.

Evening folks,

Whilst visiting the Northampton & Lamport Railway to see 6430 (on her last weekend there),I noticed that she has the 74XX layout of how the cab rear and bunker top join - square corners. 6435 also has these, whereas 6412 has the curved corners as per the 64XX design.

Were these square corners just applied to a specific Lot?.

Very Best Wishes,
Bob.

 

Yes, lot 305 - locos 6430-9 of 1937.
Ray.

 

Thanks Ray - I never knew that until now.

 

Mmm, its an example of the way the GWR sometimes did and sometimes didn't make changes across classes.
6429 had the radiused intersection in Nov '35. 7400 was the first to have the altered design in July 1936, and all that followed had the angle too. I ought to explore the absence or presence of the change across other classes.
Lets look.
1924 - 5600 - radius
1927 - 4575 - radius
1929 - 5101 - radius (all 2-6-2T, 2-8-0T and 2-8-2T had the radius intersection, even those built post 1945)
1932 - 4800 - radius (built up to 1936)
1933 - 9701 - angle
1933 - 8750 - angle
1932 - 6400 - radius
1936 - 7400 - angle
1937 - 6430 - angle
I suppose if one were really deep into this it would be interesting to explore which draughtsmen worked on which classes.