Imaginary Locomotives

[John Besley]

On 02/09/2021 at 19:39, ScottishRailFanatic said:

In response to notes on my dual-cab 08, here’s a new bogie version. Along with that, here’s an Avonside-Peckett crossover 0-6-0ST.

I do like the boxcab 08

[John Besley]

On 02/09/2021 at 19:53, sir douglas said:

2ft gauge vertical boiler meyer

Reminds me of the CMR Duncan that PD Hancock built

[billbedford]

6 hours ago, sir douglas said:

the only main difference between a garratt and a meyer is where the coal and water is and i went the meyer route. in this picture, if the cab side sheet has a coal bunker and the box below is a tank? then it makes it a meyer not a garratt, a little unnecessary pedantry i know

The salient point with the Beyer Garratt design, and for which the company was awarded their patent, was that the boiler unit was supported on the driving units with a three point suspension. 

[rockershovel]

Surely the load path for the drawgear and buffing loads differ considerably? If I understand it correctly;

 

- a Garratt or Beyer-Garratt has an engine unit at both ends, and works bi-directionally. Buffing and drawgear loads pass directly through the engine unit and pivot; the total load on the central structure equals the tractive effort of ONE engine (the drawbar being directly mounted to the trailing engine) and the articulated joints are vertically offset from the plane of the driving axles. The trailing engine (or leading engine, if banking) transmits the entire tractive effort. 

 

- Fairlies appear to be essentially similar 

 

- single Fairlies transmit the buffing and drawgear loads through the pivot to the main frame if running engine-first (i.e., smokebox-first for an 0-4-4)

 

- a Mallet has the drawbar mounted to the main frame at the trailing end, and normally works smokebox-first so that the load on the joint is equal to the tractive effort of the leading engine. This doesn't apply to tank-engine designs operating bi-directionally, or engines conducting banking duties, in which case the articulated section transmits the entire tractive effort. In either case the articulation joint is is the plane of the axles. 

 

- Meyer, or Kitson-Meyer types have the drawgear on the engine bogies so that main frame transmits the TE of one engine. 

[DenysW]

I think I may be almost entirely agreeing with Rockershovel, whilst coming at the problem from a different direction ...

 

-   Mallets and Meyers are substantially conventional locomotives - but where there are two engine units instead of one under the frame. The front engine unit (only) is articulated in the Mallet; both are articulated in the Meyer. Either can be a tank or a tender engine. Meyer's design and Mallet's patent specified compound, but many of the later US designs ignored this, infuriating purists. The benefits are extra cylinders and reduced driving wheelbase compared to rigids. Tender versions do not use the weight of the tender for traction

-   Kitson-Meyers, Garratts, du Bousquets, and Engerths  have the rear engine units under the tender as well as the cab, and so are all double-articulated  'tank engines', and also use all of the locomotive+tender weight in traction. All can add leading and/or trailing non-driving wheels to improve track wear and for leading into curves. The key difference of the Garratt (probably just to differentiate it from the earlier Kitson-Meyer concept) is to move a substantial amount of the water supply to the front in an extra tank to balance the forces on the front articulation joint

- Double Fairlies have a rigid double boiler system on top of two articulated engine units. This severely limits the coal supply as it can only be carried in side panniers. Not really suitable for compounding

- The geared locomotives (Shay, Heisler, Climax, Williamette, others) also used all of the weight for traction, but had a single engine unit driving multiple articulated wheelsets. They were slow enough not to need non-driving leading or trailing wheels.

[rockershovel]

Surely the key design point of the Garratt was to allow the boiler to be designed to the maximum limits of the loading gauge? It was well known by the time the Garratt appeared on the scene, that the boiler should be of maximum possible diameter but not more than 21' long. The Garratt was also suited to African conditions, its length was not important and its capacity to carry large quantities of fuel and water while maximising available adhesion weight

[tythatguy1312]

well I have a rather alarming, off-the-wall idea. What would a classic American 1850's 4-4-0 look like as a Pacific? Just for a laugh

[billbedford]

2 hours ago, rockershovel said:

Surely the key design point of the Garratt was to allow the boiler to be designed to the maximum limits of the loading gauge? 

 

It wasn't true of the prototypes that went out to Tasmania, nor I believe for the LMS Garratts. 

[Clive Mortimore]

On 03/09/2021 at 16:20, Compound2632 said:

 

I am aware of that! (I would hope that my avatar would give you the hint that that might be the case.) My point was that if you want to design an outside-cylindered version of a Flatiron, what you would inevitably be led to would be the Standard 4P 2-6-4T; as indeed the Derby LDO staff were.

 

Anyway, thank you for posting a photo of a Flatiron. One can never have too many pictures of Midland engines.

Yo Compo

 

Yes but no but yes but no but yer Flatiron had a H then a G7 boiler where the 4P had a G9S. Just like a 990 class 4-4-0 the best looking M R locos.

[rockershovel]

5 hours ago, billbedford said:

 

It wasn't true of the prototypes that went out to Tasmania, nor I believe for the LMS Garratts. 

 

True, and also of the 2' gauge NGG16 types; but the LMS and NGG16 types were the most powerful locomotives to run on their respective track and loading gauges. The LMS units were designed to pull 1450 tons at 25mph, the subsequent BR 9F 900 tons at 35mph (although they were capable of going considerably faster). 

[John Besley]

8 hours ago, tythatguy1312 said:

well I have a rather alarming, off-the-wall idea. What would a classic American 1850's 4-4-0 look like as a Pacific? Just for a laugh

When was the first pacific built?

[Compound2632]

6 hours ago, Clive Mortimore said:

Yo Compo

 

Yes but no but yes but no but yer Flatiron had a H then a G7 boiler where the 4P had a G9S. Just like a 990 class 4-4-0 the best looking M R locos.

 

Yo No-Primer,

 

Am aware - I meant just in a general way. All sorts of differences and the valves were the really significant change making the 4P such excellent machines. 

 

You take an interesting position on Midland locomotive aesthetics. If I didn't know any other MR locos I wouldn't disagree.

[DenysW]

Pacifics. There a Wikipedia entry dedicated to this.

 

Summary: all around the world 1906-1908. Some evidence (look at Maffei's route to get to the Bavarian S3/6) that you have to build one or two designs to learn how to get them right. UK an exception in that Churchward's Great Bear seems to have discouraged the rest.

[Compound2632]

10 minutes ago, DenysW said:

Pacifics. There a Wikipedia entry dedicated to this.

 

Summary: all around the world 1906-1908. Some evidence (look at Maffei's route to get to the Bavarian S3/6) that you have to build one or two designs to learn how to get them right. UK an exception in that Churchward's Great Bear seems to have discouraged the rest.

 

Isn't it more the case that in the operational conditions of British railways in the pre-Great War period, such very large locomotives were as yet unnecessary? With high-quality fuel readily available, the pacific's key advantage of a wide grate was not so significant. Those first New Zealand pacifics were designed to burn low-quality locally-mined coal.

Edited September 5, 2021 by Compound2632

[DenysW]

Pacifics.

 

Mixed feelings. I think if there had been a successful UK prototype running on UK loading gauge (the Germans certainly were using 4-cylinder compounds which were pretty wide at UK platform level) then the need for speed would have lead the ECML and the WCML to have started using pacifics pre-WW1. So I think there may be some circular logic in looking at what actual practice was (which was using established designs) rather than the what-if of GCR, GNR or LNWR had run parallel development with Churchward to produce the A1 pacific (and look-alikes) in 1908 instead of 1928. 

 

Northern coal poorer than Welsh so GN, GC, LNWR might have been more attracted to the opportunities than GWR.

 

Midland not a contender for this (light engine policy) unless they still had a chip on their shoulder in the 1900s from being excluded from the race to the north in the 1890s. 

[DenysW]

Articulateds.

 

Just an 'I wish I'd Known'. If you are looking for an HO articulated model to kit-bash into an imaginary OO UK loco, you'll struggle to find Mallets. Specifically:

 

-   the Roco Bavarian BB II 0-4-4-0 is a nice model, but it's a duplex, not a Mallet (no articulation at all)

-   the Rivarossi Bavarian Gt 2x4/4 0-8-8-0 is a Meyer not a Mallet (double articulation)

-   the Rivarossi Saxon 0-4-4-0 Meyer is indeed a Meyer

 

I've not looked at Trix/Marklin implementations, or the various Big Boy models (too rich for me).

 

Whatever its other imaginary aspects, the Mantua 2-6-6-2 Uintah RR No 50 is indeed a Mallet with single articulation.

[rockershovel]

10 hours ago, tythatguy1312 said:

well I have a rather alarming, off-the-wall idea. What would a classic American 1850's 4-4-0 look like as a Pacific? Just for a laugh

It wouldn't. The classic American 4-4-0 was a development of the earlier 4-2-0 type, placing the weight of the firebox and large-diameter boiler section between two pairs of driving wheels  thus maximising adhesion weight. Fireboxes were narrow and wagon-top boilers prominently tapered. Leading drivers were sometimes flangeless because bogie mounts were of the simple pin type used on 4-2-0 designs. As bogie mountings were developed and track improved, the ubiquitous "ten wheeler" 4-6-0 emerged.  Pacifics were a different beast altogether. 

[DK123GWR]

2 hours ago, Compound2632 said:

the pacific's key advantage of a wide grate was not so significant

Except for the implications it would have for the size of the ashpan, and hence the range of the locomotive?

[PhilJ W]

5 hours ago, John Besley said:

When was the first pacific built?

The first pacifics were the Western Australia Railways Q class of 1896. 

https://en.wikipedia.org/wiki/WAGR_Q_class_(1895)

[Compound2632]

21 minutes ago, PhilJ W said:

The first pacifics were the Western Australia Railways Q class of 1896. 

https://en.wikipedia.org/wiki/WAGR_Q_class_(1895)

 

But those, being tank engines, were not true pacifics - they were conventional six-coupled engines with the firebox between the frames and, as far as I can make out, between the second and third coupled axles - 4-6-0s with an additional carrying axle under the bunker. The New Zealand Baldwins of 1901 appear to be the first proper pacifics. 

 

Would you say that Ivatt's Great Northern atlantic was not the first British atlantic because numerous classes of 4-4-2T had appeared over the previous two decades?

 

The distinguishing feature of both an atlantic and a pacific is that the firebox sits behind the trailing coupled axle.

 

Edited September 5, 2021 by Compound2632

[PenrithBeacon]

7 hours ago, John Besley said:

When was the first pacific built?

http://authority.nzetc.org/tm/scholarly/tei-Gov09_07Rail-t1-body-d3.html

[The Johnster]

7 hours ago, DenysW said:

then the need for speed would have lead the ECML and the WCML to have started using pacifics pre-WW1.

There had been an agreement between the ECML and WCML company groups regarding timings since the 'Great Race To The North' period of the 1880s, and this was not rescinded until after the Great War AFAIK.  Loads were increasing steadily, resulting in 4-6-0s on the WCML and Atlantics on the ECML, but speeds were restrained and there were no non-stop London-Glasgow/Edinburgh services.  Once this agreement was off the table, it was not long before Gresley pacifics were working ever faster and longer distance trains on the ECML, and the LMS responded with the Royal Scots, and eventually the Princess Royals.  By this time you had a classic competitive situation in which each progressive loco development was countered by the other side, A1 to Princess Royal to A3, and A4 to Coronation.

 

Thus it would have been unlikely that a pre-Great War pacific would have been commercially viable in the UK even had a better version of The Great Bear been available.  Pacifics were just too big and not needed.  The GNR, NER, and NBR's atlantics were more than capable of timing the loads, and the LNW's Claughtons managed between Euston and Carlisle, albeit often with 4-4-0 pilots.  The Caley had the Cardeans, but they seem to have made not much of an impression overall.

 

The result of imposing a Midland Railway small engine policy on the LMS's WCML was that it began to look a bit pathetic compared to the East Coast route once the timing agreement was scrapped.  The Royal Scots were an attempt to redress the balance, but were no match for a Gresley pacific.  The Princess Royals were, though, and their lineage owed more to The Great Bear than the atlantic DNA of the Gresleys and Ravens (let's not forget that Sir Vincent Raven, as well as having the best goth name EVER, designed pacifics that were perfectly capable of the work they were put to, and could have been the way forward had Gresley not been the CME and naturally progressed his own designs).

 

This should not stop us having fun with the idea of Ivatt, Worsdell, Reid, or even Pickersgill or Bowen-Cooke pacifics, and maybe even a Urie one for the LSW, perhaps rebuilt from a Drummond inside cylindered failure with bigger paddleboxes than the Great Eastern.  Webb might have had a go at a 4-2-2-2-2 triple or quadruple compounded 6 cylindered duplex, each driven wheelset being of a different diameter, I mean triplex, probably painted in candy stripe or polka dot, and piloted everwhere by Cornwall.  The LMS would have rebuilt this as a simple 4 cylinder pacific at the first possible opportunity.

Edited September 5, 2021 by The Johnster

[Compound2632]

26 minutes ago, The Johnster said:

The result of imposing a Midland Railway small engine policy on the LMS's WCML

 

Myth. Folklore. Nonsense. The early LMS management was desperate to meet the needs of working the WCML, the Claughtons as built being not quite up to the job. Hughes' 4-cylinder 4-6-0s, which the LMS continued to build, were drafted in on the Crewe-Carlisle section etc. (indeed had been since the amalgamation of the LNWR and L&Y on 1 Jan 1922). One could hardly describe that as a small engine policy. It was just unfortunate that they weren't the most brilliant of engines but they were the largest to hand. 

[PenrithBeacon]

1 hour ago, Compound2632 said:

 

Myth. Folklore. Nonsense. The early LMS management was desperate to meet the needs of working the WCML, the Claughtons as built being not quite up to the job. Hughes' 4-cylinder 4-6-0s, which the LMS continued to build, were drafted in on the Crewe-Carlisle section etc. (indeed had been since the amalgamation of the LNWR and L&Y on 1 Jan 1922). One could hardly describe that as a small engine policy. It was just unfortunate that they weren't the most brilliant of engines but they were the largest to hand. 

It was also true that the Midland Compound, nominally a smaller engine, was better than either of them.

[ScottishRailFanatic]

Imagining that the British Transport Police actually had its own fleet for branch lines - trespassers have been awfully quiet since they brought these in…