111 The Great Bear

Hmm, a Pacific with equal length connecting rods and the bogie astride the rear of the cylinders must have been awful then

 

Good job the bogie didn't have to be moved forward so that the cylinders were actually behind the rear wheels. Might have been even worse...

 

It most certainly did.

 

I don't know, the more I read about TGB the more I am convinced she was the GWR equivalent of the Raven NER Pacifics. Fully capable of doing the work asked of her but an engineering dead end. I'm not actually convinced she was a terrible machine, just not as efficient and good she could have been with hindsight.

I am sure she still made a magnificent sight, lets face it.

 

The Bear was 61 ft wheelbase, 71ft 2in over buffers. The Stars were 53'6" and 63'1". I think the tender was about a foot longer than a standard one.

 

Thanks

 

Thanks - how did that compare with available turntables at the time? Did they have to enlarge them, or were the existing ones large enough?

Tom

 

Turntables at larger sheds were mostly 55ft at the time. Churchward installed 65ft turntables when OOC was remodelled in 1906, so the London end was no problem. My references don't say when a 65ft unit was installed at Bristol, but AIUI basically the Bear just ran between London and Bristol so at most only one new/enlarged turntable was required.

 

The cylinder/wheel and general mechanical arrangements were the same as the Star, which was a resounding success.

 

Assuming TGB was cut up at some loco shed. Sad it never made it to preservation. It would be an attention getter for sure.

 

Of course, as a rebuild Viscount Churchill was one of the earlier Castle withdrawals. However just imagine if it had survived into preservation - would there be calls to dismantle it for bits to recreate the Bear?

 

It was in fact rebuilt into a Castle (Viscount Churchill as above) in the 1920s when the firebox needed a major repair. A number of Stars were rebuilt in much the same way at the same time. TBH it was the sensible thing to do with it.

 

As a GWR enthusiast and a great admirer of Churchward I have long hoped to find some redeeming factor for the Bear. To be able to say "with a few modifications to the radial axle a hypothetical new build Great Bear could really show what it was capable of on a heavily graded line such as the S&C."

Sadly nothing I read shows it in a good light, except as an impressive flagship built at a time when to many people the 4-6-0 designs of McIntosh and Drummond appeared more impressive and powerful than Churchward's Stars.

Raven's pacifics were to some extent designed along similar lines to the Bear but, once the trailing axle was redesigned, proved acceptably competent until eclipsed by the further development by Gresley of his A1s. At least the design of their firebox could be developed with the previous experience of the big atlantics.

Despite Holcroft and Nock's opinions that the Bear might have been built as a prototype for the development of future designs I tend to agree with Le Fleming that it was probably built mainly for prestige and that Churchward would have built something very different if seriously considering it as a development for the future. I suspect that like Gresley he would (as he had with his original 4-6-0s) have looked across the Atlantic for inspiration; but at that time it was not necessary and he concentrated on developing the Stars.

 

JimC has put up a very good defence of The Great Bear.

For 15 plus years The Great Bear was the flagship loco of the GWR until 1923. It was a one off, but was a logical extention to Churchward's experiments in boiler design, using the Star frames and motion ahead of the rear frame assembly and wide firebox.

The rear frame extension could have been better designed with outside axleboxes, avoiding the overheating problems.

The story of The Great Bear is a very important part of GWR loco development. Research over the last 30 years has shed more light on Churchward's reasoning for building the loco, though it all ultimately comes down to his paper on locomotive boilers that has been no secret for the last 110 or so years.

Although Churchward lost interest in The Great Bear after it's conception and birth, it remained, like a prodigal son, something close to him, and there are various accounts of him being upset when Collett in effect scrapped the loco in 1923 so that the Great Bear was not allowed to overshadow the new Castles in power and size. Instead of The Great Bear being alongside Flying Scotsman at Wembley in 1924, Caerphilly Castle took it's place.

Less impressive than either many might say in appearance and size.

Go on a few years and realise that the weight restrictions for The Great Bear on GWR mainlines were pretty much nearly a thing of the past but unknown to the CME, due to the fued between Inglis and Churchward, well documented by Sir Felix Pole.

I would suggest that if you put a bigger boiler on a Star chassis you are going to get a better loco. This is what Collett did with the Castles and Kings, and what Churchward did with The Great Bear, and wanted to do with the standard 7 boiler (as per the 47xx) on the Star chassis too.

Cheers,
Julian

 

The front end was much more modern than the Raven pacifics as was the basis of the boiler, if not the firebox. The inside bearings on the trailing axle had the same shortcomings as the Raven locos and the tender and cab were still too small, but it had the makings of a better loco if developed somewhat, so not so sure about the dead end. More that the GWR didn't really need a pacific at that time.

Agreed about the majestic appearance though.

The GWR had two triangles within their Bristol lines so turning may not have been a major problem for just the one loco. Exeter would have been a problem but Plymouth also had triangles if it even got that far.

 

I take your point - the Raven really was more of a stretched Atlantic.

It is interesting - I have noted in my research recently for the book I'm writing that there was a proposal from one of Gresley's team to rebuild the Raven Pacifics with the Gresley boiler, cartazzi - and two cylinders instead of three. Have a guess who suggested that but was rebuffed...!

I'm not a GWR man by any means but I have always really liked the look of TGB. There's something wonderfully muscular about the locomotive whilst retaining the elegance of the Stars outline, with a bigger boiler. One suspects the later style Swindon cab and perhaps a better, outside bearing trailing track or cartazzi would have improved things in terms of the overall look of the machine.

 

One loco (2404) did receive an A1 boiler, cartazzi truck and Gresley cab. Interesting idea for the cylinders - they'd have to be pretty darn big to get the equivalent TE, even with an A3 boiler, and which type would they be? - the same inside Stephensons link cylinders as already used, or more modern outside Walschaerts cylinders. Major rebuild of the front end for a single small class. If there had been more of them it might have made sense.

Very true - a bigger tender would also have helped.

 

From what I gather, the intention was indeed to use two larger cylinders, maxed out to the loading gauge. An A3 boiler, pressed to 225lb and outside walschaerts valve gear (two sets). The idea being that they would be brought into line with the A1s and A3s with the boiler type, a rebuild of the front end with an experimental two cylinder setup for a Pacific. Would have pre-dated the two cylinder Standard 7MT Pacific by twenty years.

As you say, if there had been more of them it might have proven a better proposition. I suspect the intention was always to build just one in this vein to perhaps inform the next development of the A4 Pacific - but it was never implemented, as you know.

Agree with that.