GWR King class front bogie

[Combe Martin]

The King class has a unique (for the UK at least ?) front bogie.  I've never seen an explanation (apologies if I've missed it) of why it's of this design.  Can anyone enlighten me ?

[Dunsignalling]

I've always understood it to have been necessary for the bogie to adequately clear the inside cylinder block, which is larger than that used in the Castle class from which the Kings are derived.

 

That said, my knowledge of matters GWR is limited, and I am prepared to be shot down in flames. 

 

John

 

 

Edited February 7, 2021 by Dunsignalling

[Miss Prism]

52 minutes ago, Dunsignalling said:

I've always understood it to have been necessary for the bogie to adequately clear the inside cylinder block, which is larger than that used in the Castle class from which the Kings are derived.

 

Yes. To expand a bit, the story is one of vanity, compromise and an ironic hindsight:

 

The expensive insistence on using 6'6" wheels for the Kings, in order to achieve the prestigious 40k lbs tractive, led to the 'cylinder line' on the Kings being lower than that of the other big-wheel 4-6-0s, and it was found difficult to squeeze the existing Churchward barframe design in. This, and the desire to go to a plate frame design because of perceived (rivet) weaknesses in the Churchward barframe, led to the half-outside half-inside format for the King bogie. In the event, the weaknesses in the barframe structure was discovered subsequently to have arisen more from the lack of diagonal bracing rather than rivet cracking. Had this been known at the King design stage, they would probably have had a version of the Churchward barframe bogie.
 

[LMS2968]

well, the bar frames weren't too successful anyway, with the Kings being temporarily withdrawn in the mid-1950s to have their problems rectified.

[rodent279]

I thought it was also to do with rigid insistence on keeping the inside & outside con rods the same length?

[JimC]

16 hours ago, Miss Prism said:

The expensive insistence on using 6'6" wheels for the Kings, in order to achieve the prestigious 40k lbs tractive, 

Who was it who made that claim, was it Nock, Gibson or Tuplin? I'm of the opinion it doesn't stand up. Reducing wheel size on express locomotives was a general trend, and Cook tells us the reduced wheel size was an early decision. Taking the cylinders out to first rebore on the first few locomotives on the other hand... 

[Miss Prism]

1 hour ago, JimC said:

Who was it who made that claim, was it Nock, Gibson or Tuplin?

 

In the Nock book, it recounts how Sir Felix Pole confided to a close friend about "the very high capital cost of introducing the new engines, in patterns, tools and special machinery". Nock goes on to note, that the close friend (a J C Crebbin) added that "a good deal of the cost would have been avoided if insistence had not been placed upon tipping the 40,000 lb mark".

[The Johnster]

It is a consequence of the divided drive de Glehn 4 cylinder layout inherited from the Stars and Castles and the 6'6" non standard driving wheel of the King design.  The smaller driving wheels allowed a larger boiler to be squeezed into the loading gauge but it had to sit at a lower centre line, which meant that the bottoms of the inside cylinders, set forward to drive the leading axle, came perilously close to the top of the leading bogie, which had to be allowed room to bounce around a bit at speed.  This then required the front of the bogie frame to be outside the wheels to allow the frame to rise around the bottom of the inside cylinders, especially if the loco was dipping forward under braking at speed and sitting down on the front springs, the rear wheels of the bogie being inside framed as this axle is to the rear of the cylinder casting and the motion does not get in the way; there plenty clearance there. 

 

Plus it gave a nice brass outside bearing to be polished up; the GW liked a bit of polished brass on it's locos...

 

It is my view that the King would have been a much more useful loco and less route restricted if the 40k T.E. requirement had been dispensed with; it would probably have replaced the Castle as the standard GWR express loco, though Castles would have been retained for the fastest jobs (Bristolian, Cheltenham Flyer).  Canton, for example, could have had Kings 35 years earlier than it did, and they could have worked down line, so Landore could as well.  They could have worked through Oxford, useful for cross country services, and Swindon-Gloucester-Severn Tunnel.

[LMS2968]

7 minutes ago, The Johnster said:

Plus it gave a nice brass outside bearing to be polished up; the GW liked a bit of polished brass on it's locos...

A very important point in Swindon D.O!

[JimC]

If we are honest the King didn't quite make nominal 40K TE anyways so it cannot have been a fundamental design aim.  Truth is the King primarily got to 40K by being a bit economical with the old actualité! Its come back to me that in Pole's book he states that it was coming out just below 40K, and he asked if they could not get it over the limit. He then talks about wheel size, but his memory must have been playing him false, because its clearly the first rebore numbers manipulation that nudged the Kings over 40K. As Cook says the smaller wheels were a key part of the design.

 

The thing is though, unless the King was going to be a significant advance on the Castle what was the point of introducing it? The Great Bear had a boiler with, I believe, the same pitch and same diameters as the King over 6'8.5 wheels, so it was possible to squeeze it in over the larger wheels. We might note, though, that the smaller wheels saved a bit of precious weight.  As for RA, surely it wouldn't have been affected if they had designed it for 21 tons or whatever - new GWR bridges were already being built for the 23 ton limit, and older ones had been constructed for 19.5. A 19.5 axle weight limit King would have been a Castle.

So, all locomotive designs being compromises, what alternate compromises could Collett have considered for the King? Larger wheels and a slightly lighter boiler would have given slightly less capability for heavy trains, and a lot of GWR loco development over the preceding years had been about increasing train weight.  

 

 

 

Edited February 8, 2021 by JimC

[The Stationmaster]

21 hours ago, LMS2968 said:

well, the bar frames weren't too successful anyway, with the Kings being temporarily withdrawn in the mid-1950s to have their problems rectified.

As Johnster has said the outside frame was necessary for the leading wheelset on the bogie to allow space for the insif de cylinders and of course there was bo room for an outside frame on the trailing wheelset because of the position of the outside cylinders.   Not really a problem, on some respects, mixing the two but the bogie design itself as originally built was inadequately sprung hence the early addition of coils springs for the leading axle and what - from contemporaneous photos - appears to be an enlargement of the coil springs fairly soon after their initial adoption.  

 

21 hours ago, LMS2968 said:

well, the bar frames weren't too successful anyway, with the Kings being temporarily withdrawn in the mid-1950s to have their problems rectified.

Bit of a tangle there methinks.  The 'Kings' had plate frame bogies, not bar frames.    And cracks were detected in some bogies during a campaign check in 1955 following the discovery of fatigue cracks on 60700 on the ER.  the cracking on the 'Kings was dealt with by welf ding four strips of substantial metal to the outer sides of the bogie and taht seems to have cured the problem but it is not clear from any published accounts just how far back the instances of cracks dated.

[melmerby]

How did Stanier get around the bogie problem on the Princess, considering it has virtually the same front end? (Apart from the valve gear inside/outside being reversed)

Even the cylinder centreline seems to be the same.

[Miss Prism]

53 minutes ago, JimC said:

Its come back to me that in Pole's book he states that it was coming out just below 40K, and he asked if they could not get it over the limit. He then talks about wheel size, but his memory must have been playing him false, because its clearly the first rebore numbers manipulation that nudged the Kings over 40K. As Cook says the smaller wheels were a key part of the design.

 

Nock gives an interesting table giving the increases (compared to a Castle) in the nominal tractive effort attributable to the various King features:

 

-  990 lb, cylinder diameter increase;

- 2580 lb, cylinder stroke increase;

- 3980 lb, boiler pressure increase;

- 1145 lb, coupled wheel diameter decrease.

 

[johnofwessex]

But...........

 

As far as I understand it, the wiggly bits on a King or Castle were capable of great things, BUT the capacity of the boiler perched on top of them wasnt up to maintaining the potential power output for any length of time.

[rodent279]

1 hour ago, melmerby said:

How did Stanier get around the bogie problem on the Princess, considering it has virtually the same front end? (Apart from the valve gear inside/outside being reversed)

Even the cylinder centreline seems to be the same.

Good question. Did Stanier insist on equal length con rods for inside & outside cylinders? Did he allow the inside cylinders to be slightly inclined? One or both of those two factors may have allowed the use of the standard Swindon-de Glehn bogie on the King.

[The Johnster]

1 hour ago, JimC said:

So, all locomotive designs being compromises, what alternate compromises could Collett have considered for the King?

Fair question.  But was the King needed in the first place?  Pendennis Castle had proved itself the superior of a Gresley pacific only a few years earlier, and Gresley had responded with the A3, which I would argue was as powerful and fast a loco as the LNER or any other UK railway ever really needed.  Castles were already in the ball park of being that good, so what was the point of improving on them?  So far as I can see the main benefic was to increase loadings and reduce timings on the West of England main line, and even then the prime service, the Cornish Riviera, was a Limited.

 

At the risk of sounding like Professor Tuplin, a Castle with 3 slightly bigger cylinders and a slightly enlagred boiler might have been able to achieve most of the improvements that the King delivered, while being no more route restricted than a standard Castle, easier to prep, and retaining the 6'8" driving wheels that gave Castles the edge for top speed.  Apart from that, in 1927 the only place left to go was pacifics, not something with a good track record on the GW, something like a Princess Royal.  This has been discussed to death; pacifics were rejected on the GW because of concerns with their grip on the South Devon and South Wales banks.  My view is contentious, but not deliberately so; the Kings were a failure which is why only a limited number were built, the railway then reverting to Castles until 1950, well past their sell by. 

 

This may explain some of the small c conservative locomotive policy and fiddling about with Churchwardian driving wheel sizes that characterised Collett's approach.  The GW, with longer distances of clear run between express stops or speed restrictions than the LMS or LNER, could get away with high average speeds without having to run up to the high 90s or low 100s that were an almost daily occurrence on the ECML, and its non-stop runs were shorter than the LMS (who cheated by stopping to relieve crews at Upperby) or LNER's.  All of which further mitigated against pacifics.  Where else do you go, 4-8-0s?  But to get a decent width firebox between driving wheels further restricted by the further set back trailing driven axle, you need to bing the driving wheel diameter down, and the longer boiler needs a longer firebox than a King's, already pushing how far the fireman can throw the coal with the shovel.  The arrangement worked well in France, where there is a bigger loading gauge.  4-4-4s?  Maybe, for lighter loadings and good riding at high speed, nice wide firebox and 7' drivers for Bristol-Paddington or maybe Oxford-Paddinton non-stop flyers, but not much use for much else.

 

Only a dozen years and there's another war, and following that the whole game changed and all the previous bets were off.  Now, the emphasis was on easy prep and disposal, burning any old coal efficiently, free steaming boilers, and good haulage up to around 70mph, the speed limit until 1953.  New express locos tended to have smaller driving wheels and there were no new 4 cylinder designs after the Coronations, and the GW was frankly left with an outdated loco policy that it clung to for far too long and no idea how to dig themselves out of it, a culture that trumpeted it's successes* loudly enough to drown out the complaints and of elephants in drawing offices.  Preferring Castles or 28xx to Britannias and 9Fs in the early 50s was not going to make them any friends and they seemed to be living in the past, not just living on past glories.  Hawksworth's Counties are in some ways irrelevant, a nod to the new world but really an opportunity to use boiler jigs at Swindon that had been used for MoS Stanier 8Fs.  There was no significant express passenger locomotive development at Swindon after the Star, which was fattened to become the Castle and the King; I would argue that developing it beyond the Castle was well into the laws of diminished returns. 

 

*In 1950, Swindon managed to prove that a Dean Goods could out perform and out steam an Ivatt 2MT mogul, and then improved the Ivatt to be able to haul 20 coaches on the level at 60mph.  So, what, that's a reason to build more 4 cylinder de Glehn 4-6-0s over 2 cylinder modern pacifics?  Or maybe more Dean Goods' to replace Ivatt 2MTs?

 

 

[LMS2968]

32 minutes ago, rodent279 said:

Good question. Did Stanier insist on equal length con rods for inside & outside cylinders? Did he allow the inside cylinders to be slightly inclined? One or both of those two factors may have allowed the use of the standard Swindon-de Glehn bogie on the King.

On the Lizzies, between centres the inside conrods were 8ft 6.5in and outside rods 9ft 0in. The inside cylinders were horizontal; only the outside ones were angled.

[rodent279]

2 minutes ago, LMS2968 said:

On the Lizzies, between centres the inside conrods were 8ft 6.5in and outside rods 9ft 0in. The inside cylinders were horizontal; only the outside ones were angled.

That may have been why WAS managed to fit the Crewe version of the Swindon-de Glehn bogie on the Princess then. Or did the Crewe version have different size bogie wheels?

(I believe one of GJC's sacred cows was the con rods should be the same length inside & out. I suspect CBC was unwilling to challenge that.)

Edited February 8, 2021 by rodent279

[LMS2968]

3ft 3.5in on the Lizzies. What about the boilers? Lizzies' were 6ft 4.75in O/D at the firebox and 5ft 8.625in at the smokebox. The centreline was 9ft 1in above the rails.

[rodent279]

2 hours ago, Miss Prism said:

 

Nock gives an interesting table giving the increases (compared to a Castle) in the nominal tractive effort attributable to the various King features:

 

-  990 lb, cylinder diameter increase;

- 2580 lb, cylinder stroke increase;

- 3980 lb, boiler pressure increase;

- 1145 lb, coupled wheel diameter decrease.

 

So, if the cyl & wheel dias had been kept the same as the Castle, another 1865lb TE would have to be found to get over the 40K target. Could that be gained from a further increase in boiler pressure alone?

[rodent279]

36 minutes ago, LMS2968 said:

3ft 3.5in on the Lizzies. What about the boilers? Lizzies' were 6ft 4.75in O/D at the firebox and 5ft 8.625in at the smokebox. The centreline was 9ft 1in above the rails.

So they were 3.5" larger than the King's, so maybe that blows that theory of of the water.

[JimC]

43 minutes ago, rodent279 said:

(I believe one of GJC's sacred cows was the con rods should be the same length inside & out. I suspect CBC was unwilling to challenge that.)

My understanding is that if you want the same valve gear driving inside and outside cylinders and you want really good regular valve events you need equal length rods. In fact the King rods were different lengths, but only marginally. AIUI the LMS didn't regard regular valve timing as being nearly as important as the GWR did, which I understand is handily demonstrated with the Duchess valve gear missing all the subtleties.

[2251]

19 hours ago, Miss Prism said:

 

Nock gives an interesting table giving the increases (compared to a Castle) in the nominal tractive effort attributable to the various King features:

 

-  990 lb, cylinder diameter increase;

- 2580 lb, cylinder stroke increase;

- 3980 lb, boiler pressure increase;

- 1145 lb, coupled wheel diameter decrease.

 

Holcroft says in An Outline of Great Western Locomotive Practice 1837-1947 (at page 145) that a Castle appeared "late in 1926" with 6'6" coupled wheels, rather than the usual 6'8.5", presumably as a trial.

 

Does anyone know any more about that? Not least, which of the Castles was modified?

[The Stationmaster]

1 hour ago, 2251 said:

Holcroft says in An Outline of Great Western Locomotive Practice 1837-1947 (at page 145) that a Castle appeared "late in 1926" with 6'6" coupled wheels, rather than the usual 6'8.5", presumably as a trial.

 

Does anyone know any more about that? Not least, which of the Castles was modified?

5002 had the driving wheels turned down to 6ft 6" but it was made sure that it had new tyres because turning them down that far was below scrapping size for the tyres on a 'Castle'.  the engine was run on all the 'crack trains' without any problems thus proc vinga driving wheel of that size was perfectly usable in normal service.

(Source K.J. Cook' book 'Swndon Steam 1921 - 51')

 

Then sufficient 'Kings' were built to carry out the heavier work expected of them.  All too easy to forget at this distance in time  that the 'Kings' were allowed loads as much as 40 - 50 tons greater than thoise for 'Castles'

[D826]

Nothing to do with the front bogie but any more seditious talk about the Kings and you'll be having the spirit of my late father come pay you a visit in the small hours !

 

As far as he was concerned they were 'the engine'.  

 

If you look at the loads and speeds they were doing on the Inter City, (see a lovely little book called "Watching the Trains at Brill"), they must've been impressive in full flight with bloody great loads rattling through Saunderton, Risborough and Haddenham. 

 

The book has timings of King hauled trains with 14/ 15 coaches and more on.

 

Mind you, Dad loved Castles and as a goods/pway driver he said the Halls could do anything.  To be honest Swindon could have put a copper capuchon on a Suffolk Punch lawnmower and Dad would have said it was the proverbial dogs undercarriage. 

 

In fairness, he observed, and was part of practice on the Met/Great Central lines.  He also rhapsodised about the merits of V2s, B1s, and Black 5s.   By the time there were Patriots on the London extension they were knackered.

 

However, and less like a King - (apologies for drift )-  it was the humble pannier tank he loved and drove for LT till 1971.  After Met E and F Class   he said Panniers were like power packed pocket rockets !  Stopping was the skill.  He loved driving them, to the extent he used to fondly reminisce 24 years later just before he passed away.  

 

I took him to the Met 100 yr celebrations at Aylesbury in 92 when King Eddy 1 and Nunney Castle topped and tailed trains out to Quainton.  That Western exhaust bark (no other word for it) reverberated round Aylesbury.  Could hear it running at home the other side of town in the evening.

 

If you knock the Kings though, you'll be hearing the clanking of couplings taking up the slack as the old man opens the regulator and comes to give you a piece of his mind.  

 

(All entirely tongue in cheek).

 

Great RM web. Halt thread drift.  As you were chaps

 

Best regards

 

Matt W

Edited February 9, 2021 by D826
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