Class 8 shortage

Ignore the bias Ian, nothing will change anyone's minds about anything to do with steam Locos!

 

Also worth remembering that not all class 7 and 8's are equal despite the classification, 5043 at times thinks it's a King and is certainly above the single chimney variant despite both being badged as 7, certainly it's trusted with the normal Pacific/Class 8 load of 9 to Plymouth where no other Castle is.

Where does this figure of 600 tons comes from for an original A1 ?, what I'm struggling with in my mind is the fact they were put in their place by an original spec Castle, yet a Castle of any spec would struggle with 600 tons *confused*.

 

Aye, especially those with no operational experience.

 

The GNR traffic department wanted a loco capable of hauling 600 ton trains at 60 mph and that is what Gresley produced.

 

They didn't stay in their place for long though....
Wasn't the major difference between the classes in the trial one of fuel consumption rather than power?

 

From 'British Pacific Locomotives' by Cecil J Allen, 1962, Ian Allan Ltd, SBN 7110 0261 4:

The bigness of the Gresley mind equally was reflected in the bigness of his locomotives. More than any other British locomotive engineer he specialized in a 'big engine' policy; instead of letting his locomotives catch up on events, he built for the future, as with No. 1470, which he proclaimed would be adequate for the haulage of 6oo-ton trains at a time when a 400-ton load on the Great Northern main line was regarded as very heavy indeed. Bit by bit, as new Pacifies were added to the London & North Eastern stock and the 'A3' and 'A4' classes later joined the original 'A1s', Gresley provided the London & North Eastern Railway with a stud of powerful locomotives which had ample reserve to meet every possible extreme of load or weather without needing pilot assistance, or, on the other hand, losing time.

They would do it, too, although the fireman would have had a busy time. The Castles were not designed with that sort of loading in mind, so the comparison doesn't really apply. As stated above, it was the Castle's coal consumption which showed the way, and led to the A3 with long travel/long lap valve gear. But the A1's brute strength was there at the start; it had the boiler power to achieve it.

 

Yeah, there's not much in the trials that shows the Castle significantly more capable than the A1, other than in accelerating a train out of King's Cross. Its just that it did the same work with a lot less fuel and water.

 

600 tons @ 60 mph is missing one vital statistic and that is the gradient it has to do it on. The GN main line isn't quite as much of a billiard table as the GC main line but it is still generally flatter than most other main lines.

 

my mistake on 4472 being a class 8.

 

I would not call the GC main line north of Nottingham a billiard table, Steve. Quite a bit of 1 in 100 about. A bit steeper than Stoke bank.

 

No, in hindsight I chose a wrong comparison. The GN is more of a billiard table, certainly when compared with the othe main lines.

 

But not the GW main line to Bristol.

 

Interesting reading, thanks guys.

 

No, that is downhill in both directions! So they say. .

 

Either that or the mileposts are closer together than they should be .

Tom

 

Not wishing to divert the conversation, but although Doncaster fitted 250lb boilers to the A3's, they were set to 220lb pressure. Since Doncaster had the somewhat unenviable job of maintaining - and frequently replacing - A3 frames it seems highly likely they had a very good reason not to use the full available pressure. A Kylchap A3 is quite powerful enough in practice to compete with an A1 or A2 without upping the pressure - but even then they knackered their frames.

Every loco has a weak spot - some have several! and in general Doncaster seems to have accepted the frames issue as a reasonable thing to live with on an otherwise extremely effective loco. Once geared up to deal with the issue on a large class of locos I doubt it created prohibitive cost penalties. But equally I don't suppose they wanted to risk the situation becoming more serious, shortening the intervals between overhauls for example.

Of course, the increased power could have been catered for in preservation with the much less intensive use of the loco compared to BR days - increased and more careful maintenance plus a plan for dealing with the inevitable cracks - that clearly isn't what happened. Such an approach would have made it more expensive to run on mainline specials than class 8 competitors - but then it is Flying Scotsman and should have been able to command a premium.

As I keep trying to tell people in another context, putting everything to 11 simply means it will go pop

 

Speaking of 8P locos this photo appeared of Britannia covered up for what looks to be the winter on the MHR blogs. Are we expecting her to be out of action for a considerable amount of time now?