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Imaginary Locomotives


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1 minute ago, RLBH said:

Since unreasonably large locomotives have come up, the North American loading gauge is approximately a seven-eighths scale version of the British loading gauge. This is demonstrated by the ability of American prototypes in H0 scale to run on British 00 layouts.  So why not scale down American locomotives in the same proportion?

 

Taking the Union Pacific Big Boy for starters. The resulting unreasonably large locomotive has four cylinders, of 21" bore and 28" stroke. We know this fits in the loading gauge, a fair few locomotives have done it. Driving wheels are down to 60", which we know is perfectly fine for fast freight turns. Working pressure drops to 225psi, thanks to the smaller boiler. This is all very reasonable, and gives us a tractive effort of 78,720 pounds. Grate area would be about 88 square feet, with a power stoker and an unreasonably large tender being mandatory to keep it fed. The locomotive ought to weigh in at about 230 tons, with an axle load of 20.5 tons.

 

The boiler is going to be immense - 19'3" long with a 7'9" diameter - which will cause major loading gauge issues. Directly scaling from the American locomotive winds up at 14'3" tall. By reducing the clearance between the boiler and running gear, it should be possible to get down to 13'8", which is at least within the realms of possibility on some British lines. Making it a Garratt would probably remove the objection altogether, but we'll quietly ignore that point...

 

As far as tender capacity goes, scaling down from the Big Boy gets us 16.75 tons of coal, which seems reasonable for the size of the grate. It would also give us 15,000 gallons of water, which is disproportionate by UK standards. Scaling off the 9F's coal capacity, anything between 9,300 and 13,700 gallons seems reasonable. Go for 11,500 gallons. Using the Big Boy tender's load-to-weight ratio, that's a 118.7 ton tender; scaling from a BR.1, could be anywhere from 120 to 130 tons. Call it 120 tons on 6 axles, probably a bogie tender as well, though if it's at the higher end of the range a 7-axle 'centipede' tender might be needed. Might even be worth a Vanderbilt tender to save on weight.

Obviously, this is a big machine. Realistically, the Big Boy is designed to haul long freights up big hills at reasonable speeds, and this will be similar.  Shap and Beattock don't cut it, in my book, to give the 4-8-8-4 a chance to stretch its legs. They're reasonably steep, true - but they're not long enough. They can be tackled by building up a good head of steam, charging the hill, and mortgaging the boiler to get over the top. Ais Gill is long, but not steep enough - trains will hit a length limit before the tonnage limit (1).

 

There's only one place in Britain that I can think of with a big enough hill to truly compare to the duties the Big Boy was meant for. And fortunately, the company that built it was a 'big locomotive' railway with a history of doing new things - it built, for instance, the first British 4-6-0s. 

 

I am talking, of course, of the Highland Railway's main line from Perth to Inverness. Operating conditions on the Highland Main Line are generally more similar to American railroads than they are on other British lines, with long, steep hills where the boiler will need to work at equilibrium and long sections of single line which dictate running longer trains in preference to more frequent trains. If you're going to try and fit an American-style locomotive, it's the place to do it. Southbound from Inverness, it's 22 miles of climbing, mostly at 1 in 60, from a dead stop at sea level to 1,315 feet. Northbound, Drumochter isn't quite as steep but is longer. This is comparable to the grades that Union Pacific had to deal with in the Rockies. 

 

On a first approximation, it should be able to handle a 1,145 ton freight southbound from Inverness over Slochd - ruling gradient 1 in 60 - and 1,415 tons northbound from Perth over Drumochter at 1 in 70. That's actually relatively sensible, working out at about a 55 wagon train - which could and did run further south. So there shouldn't be too much of a problem with coupling strength.

 

A British-sized 4-8-8-4 actually makes some sense in the Highlands.  'Big Boy' is an unlikely name for such a machine. I call it 'Domhnall Beag' - or, translated from Gaelic, 'Little Donald'. It seemed fitting. We'll need to bore out or skylight the tunnels at Killiecrankie and Dunkeld, but more challenging civil engineering has been done.

 

The only problem is that there isn't enough traffic to justify it. The modern Oxwellmains to Inverness cement working today is about right - it's a 1,400 ton train, usually entrusted to a Type 5 diesel-electric and running as a Class 6 fully-fitted freight, permitted up to 60mph. The ideal size and class of train for Domhnall Beag to haul. Unfortunately it only runs a couple of times a week, and that's with today's traffic requirements. Justifying it would need a lot more freight running to (or from) Inverness during the steam age, and a railway willing to spend the money on a specialised locomotive to handle it.

 

That might make Ais Gill a better bet. Just lengthen the loops to handle 80 to 100 wagons. Can't be that difficult, right? Alternatively, it's not too far off of being a pair of 9F engines with a common boiler, so would be appropriate for any turn of duty that routinely needed double-headed 9Fs. The Ebbw Vale and Consett ore trains, for example. Axle load is higher than the 9F, but any line seeing that kind of regular heavy freight traffic ought to be able to handle it.

 

A similarly scaled Challenger 4-6-6-4 is well within the realms of sanity - it's pretty comparable to Powells proposed 4-6-2+2-6-4 for Preston to Glasgow and Perth. The passenger equivalent, a 7/8ths scale Union Pacific FEF-3, is actually slightly smaller and appreciably less powerful than the proposed LMS fast mixed traffic 4-8-4.

 

(1) Tonnage limit on Ais Gill would be about 2,150 tons, requiring 85 16-ton coal wagons or an equivalent.

That's an excellent point - a mini Russian Decapod wouldn't be that different from a 9F...

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Just now, Gibbo675 said:

Cheers mate !!!

No I meant the Crosti-Caprotti class 5! Though it does look a bit neater than the Crosti 9F, and who knows, maybe would have worked better.

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8 hours ago, Murican said:

True, but what about the A3s and A4s thereafter? Would there still be room for them somewhere on the LNER?

During the war right up until the early fifties they would have been very useful for the longest and heaviest trains. A version with smaller drivers but not as small as the P1's would make an ideal mixed traffic locomotive. Thompson made a big mistake in converting them to pacifics IMHO. 

6 hours ago, 33C said:

These are quality! Finish 'em! Mad liveries and a Steam-punk shed diorama like the Beeching report never happened and Marples got run over!!

Preferably by a train.

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Just now, ScottishRailFanatic said:

Aye, you're right.

An interesting idea would be having a compartment for the fireman to supply a boiler, with the steam powering multiple bogies via articulated joins... Somewhat like a UP big boy with articulating wheelsets

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23 minutes ago, Rockalaucher101 said:

You'd eventually wind up with a DMU...

SMU surely! The GWR almost got there. If you were to put one of their 0-4-2 tanks inside the body shell at the leading end (rather than a separated loco) and add two trailers you get a steam version of a Hampshire 3H DMU. In reality the separated out loco drivable from the other end of the train, be that a pannier or an aforesaid 0-4-2, was more flexible and so the adopted version. They then went diesel. Other companies had similar push-pull arrangements. 

 

The single unit was the steam precursor for the railbus.

 

Edited by john new
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4 minutes ago, ScottishRailFanatic said:

My idea was to use vertical cylinders with an articulated drive-shaft to all bogies, but with a gearing ratio allowing for higher speeds - a super-Shay style of mechanism, maybe?

An interesting way of doing things to be sure. Not sure how well that'd work though if running with multiple units. I suppose you could combine our collective ideas to get something that may work. I was more thinking along the lines of the bogie used on the GWR railmotor, just more of them

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16 hours ago, Murican said:

Looks like if Riddles was more impressed with the V4.

Looks perfect for the former GWR. Though loading gauge may tell me otherwise.

Hi There,

 

My thoughts were that the Kitson-Meyer would be for the South Wales coal traffic and the Garret for Toton-Brent Traffic to supplement or replace the LMS Garrets, with the Mallet hauling the fast container trains on the east and west coast main lines.

 

Gibbo.

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Actually if you turn the cylinders through 90 degrees and have them running under the floor, transverely it should still work. The main problem would be clearance for the driveshafts at platforms. Then again, the GWR diesel railcars had not entirely dissimilar gears on the drives.

Edited by BernardTPM
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3 hours ago, john new said:

GWR almost got there

According to T Hurry-Riches, who was CME Taff Vale Rly. and sent to Plymouth by the TVR to assess the GW's steam railmotor operation, they got closer than a steam loco dressed as a coach; he says in his report to the Taff's board that he saw a 4 car train in operation which consisted of SRM/Driving Trailer/DT/SRM, all 70' vehicles.  This would, coupled in the standard way of GW auto working, have required two loco crews and, if on board ticket sales or collection were needed, two guards  It would have been impossible to couple the auto gear between the DTs.  4 car operation in the Plymouth area was mostly used for the Satlash services, but it is possible that this train was for a service that split at some point; it would be a simple matter of parting the vacuum hoses and uncoupling, with no TRG to deal with.  Not quite an 'SMU', but close.

 

The Plymouth SRM/DT sets were gangwayed within the 2 car sets, and continued in this form when the SRM's were converted to DT's, a small driving cab being provided in the intermediate trailer, but probably never used.  The TVR built SRM sets with a similar gangwayed layout but no cab in the intermediate trailer, and again this was continued when the SRMs were rebuilt as auto trailers.  There were 3 sets, which lasted until BR days and were allocated to Tondu after 1953, each in turn, last being withdrawn in 1958.  They were ostensibly for the Porthcawl branch but were used on the other Tondu branches as well.

 

I would have thought the Sentinel/Doble layout would have been most suitable for steam MU operation; it would have been difficult to longitudinally balance a Shay or Climax configuration for a passenger vehicle, and offsetting the coach body would mean difficulty with platform access from the side offset away from.  The 'works' need to fit beneath the body to the greatest extent possible, and experience with SRMs which proved underpowered suggests that each axle needs to be driven, Doble style.

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12 minutes ago, BernardTPM said:

Actually if you turn the cylinders through 90 degrees and have them running under the floor, transverely it should still work. The main problem would be clearance for the driveshafts at platforms. Then again, the GWR diesel railcars had not entirely dissimilar gears on the drives.

That's an excellent point - I could maybe try and integrate the cylinders into the main body frame in the boiler room, or have them running under the chassis in a condensed format.

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A bit of a colour difference in this edit - the shade of crimson does seem to change from model to model - but the premise is the same. The cylinder block is now horizontally welded to the chassis of the coach, and it's been converted to a non-corridor unit for maximum people-moving efficiency, but the general idea remains unchanged, as does the boiler-room position. Still the clearance issue to sort out - maybe some modified thin bogies and the use of steel in the construction of the driveshaft so as to sustain durability while allowing for a thinner shaft?

New Project-9.jpg

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How about a three car unit with a driving cab at one end and a locomotive portion at the other, and a corridor connection on the locomotive portion? Then two units could be coupled locomotive portions together, and a single fireman tend both boilers through the corridor connection.

Edited by JimC
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