1450

Didn't know that - what makes it inaccurate for other members to wear it?

 

I think it was something like that when the class was renumbered some of the class were refitted with a top feed on the boiler. 1450 did not have this modification, and is the only preserved member of the class without a top feed on the boiler - hence the reason why it can carry the number 4850.

I found an explanation of what a top feed was on Wikipedia, by the way as I had no idea!

Top feed: A check valve (clack valve) in the feedwater line, mounted on top of the boiler. It is intended to reduce the nuisance of limescale. It does not prevent limescale formation but causes the limescale to be precipitated in a powdery form which is easily washed out of the boiler.

 

No - the boilers were swapped randomly - nothing to do with re-numbering or liveries.

 

Got the info from the GWSR website which stated

During their life the class remained practically unaltered except for the fitting of a top feed on the boilers when they returned to Swindon for overhaul. Not all were so modified, however, and 1450 is one of those that was not

http://www.gwsr.com/news/features/steam-locomotive-features/14xx-autotanks.aspx

I don't know when the other 3 were refitted, but 1450 is the only one visually in 'as built' condition so can carry the number 4850 with the shirt button as a result.

 

I thought that there were two top feed versions & two backhead clack versions in preservation - if 1450 is backhead & 1466/1420 are topfeed is 1442 backhead?

The statements re origonal unaltered condition are rubbish - the locos would have carried quite a few different boilers during their lives & it would be a matter of luck which type was carried at a particular time. Can't quite how many boilers were built for the 75 locos of this type but would expect it to be around 80 to allow for a repaired stock at the works.

 

1442 has topfeed as well - 1450 is the only one without. Topfeed had started to come in before the renumbering took place, so there's nothing really to stop any of them being numbered back as 48's, though as the roundell had been phased out by then it's a bit of a narrow time frame. Would be nice to see a propper old spec 48xx though.

 

With all the un-clad boilers I've seen at Didcot over the years, the earlier ones simply had the back head feeds blanked off when the loco was converted to top feed. i.e. 3650's boiler C8728, as a late 1940's build, never had backhead feed. 3738's boiler being earlier, has blanked off backhead feed's.

They wouldn't have retro converted the pipework back, but would have probably have selected a back head feed boiler for an un-converted loco. It would be interesting to find out if Swindon blanked off the top feed flanges on an older converted boiler that also had backhead feed, so that it could be used on an un-converted loco such as 1450? Who knows, maybe all the boilers had both options.

 

I don't think that the top feed flanges would be blanked off once fitted for two reasons:
1. This must have been a design improvement using standard clacks as fitted to the larger locos with top feed and giving a better delivery point for the feed water with less internal pipework.
2. How would you "hide" the blanked off pads under the cladding?

 

Certainly on small small tank engines where the top feed is not part of the safety valve casting, the flanges are only 6" diameter and only stand up about 1 1/2" once the delivery pipe and pedestal are removed. A "nutted" blanking plate, with the studs cut off would certainly disappear under a couple of inches of lagging once the cladding was wrapped around.

I have 8 late 1950s photos of 14xx's. 4 of them don't have top feed. With that many not converted you're probably right. They wouldn't have blanked them off so a converted boiler could fit a non converted loco, but it could have been an option,... who knows.

Does anyone know what the delivery pipe arrangement was on backhead feeds, if any? You can see the top feed delivery pipes and how they direct the "cold" water in the third photo. The main reason for changing to top feed was to prevent "cold" water going in over the top of the hot firebox and causing stressing at the hottest point of the boiler.

 

Based on several backhead feed boilers i have seen and worked on, admittedly not GW ones the water delivery is routed with an internal pipe to the front section of the boiler barrel. I can't imagine the GW would have deviated from this arrangement, but if they did i'm sure some one will tell me!!

 

The backplate pads simply have blanking plates fitted to them on boilers that had the topfeed alteration.
Cant remember when topfeed modifications started but the shirtbutton period ended ~'42. There may only have been a few modified boilers in '42 so chances a modified boiler was swapped to a loco without receiving a repaint would limit the chances of there being a topfeed loco in shirtbutton livery.
If there were no internal feed pipes there would be localised cooling causing stresses to the firebox, they would most certainly be fitted, the position of the clacks being just above the inner firebox shoulders gives something away!

 

1363 is the same, so I'd imagine the rest were like that.

 

Not totally sure, but I think the 48xx boilers started being modified around about 1944.

 

The entire class of 48XX were renumbered on mass to the 14XX series when some of the 28XX/38XX series were renumbered to the 48XX series, upon conversion of some of the 28/38 series to oil firing