Jim Champ's "Introduction to Great Western Locomotive Development"

Some notes,
5100, ex 3100 née 99 seems to have had the small sloping water tank all her life. Its visible in photographs of 99, when she had a vertical back on the bunker. The 3111s all seem to have had the higher flat topped (at least at the sides) tank from new which was unchanged when the bunker extension was added.

The 3150s that were built with water pickup apparatus (3166-70) had the vertical section at the back of the tank as shown which accommodated piping for the water pickup apparatus. After the gear was removed and the bunker extended these tanks were altered with a sloping top section of the style shown in the other sketch. At least some, if not all of the 3150s built without water pickup apparatus, both before and after 3166-70, also had the upward extension of the tank. 

The tank style on diagram A13 for the Collett 3100 doesn't seem to have been constructed on any of the class. Another demonstration of why its wise to be wary of weight diagrams. Photographs show the 3100s with the style shown in the other graphic, presumably unchanged from their previous incarnation as 3150s.

 

Edited May 20, 2021 by JimC

Should there be an extra bunker diagram for 3131-50?

 

 

Edited May 23, 2021 by Miss Prism

I'm not clear on what the difference between 3111-3130 and 3131-3150 is.

I suppose what I'm saying is that maybe there should be an extra diagram:

 

 

Do you think, though, the other rivet lines represent tank boundaries or simply fabrication of the bunker assembly? I've taken the viewpoint that only the very closely spaced lines of rivers represent a tank edge, and others are boundaries of plates and/or transverse structures. With my 'no rivets' policy those are best left off. 

I'm already concerned that the sketches are misleading as there are lines on some original drawings that suggest that what looks superficially like a flat topped tank is actually anything but, and on the inside the tank top slopes down to the floor in the centre. 

Anyone here familiar with the preserved 5101s and 61xx and can comment? 

2 hours ago, JimC said:

Do you think, though, the other rivet lines represent tank boundaries or simply fabrication of the bunker assembly? I've taken the viewpoint that only the very closely spaced lines of rivers represent a tank edge, and others are boundaries of plates and/or transverse structures. With my 'no rivets' policy those are best left off. 

 

I see what you mean, in which case, the tank boundaries are probably better denoted by a line that does not resemble rivets. e.g.:

 

 

Brian Daniel's albums always a good source of pics

 

They are all meant to be dashed lines, but I see some of them aren't obviously so. I'll tweak. 

 

And aha, so that's what the group of 3 rivets on all the bunkers is - a lifting ring. 

Edited May 24, 2021 by JimC

Now I think about it again, I'm wondering whether the tank position shown on Diag A13 is the centreline of the locomotive, whereas the rivets inevitably show the tank at the side. Unfortunately there are no survivors of the Churchward era bunkers.