Imaginary Locomotives

[TerryD1471]

17 hours ago, Mike 84C said:

I cannot really see where a 9f was developed from a 8f WD 2-10-0 apart from the wheel arrangement  and wide firebox, to me as different as chalk and cheese. 9f was a far more sophisticated machine.

 9f's had very good steam passages so the engine could breath very easily, small wheels do not inhibit speed if the steam can get in and out of the cylinders quickly. Look at the N&W J1.

  The 9f was good on the S&D because the S&D has a roller coaster gradient profile, which does not encourage high speed but the loco has power enough to overcome this.

  It was "wire drawing" at the throttle which increased wear on the valves and pistons which put paid to regular 9f high speed exploits. Think of piston speeds, stopping and restarting at each end of the stroke, at speeds in the 70/80 mph mark. Its a wonder the gudgeon pins in the little ends took that kind of strain.

  Annesley 9f's on the runners were up in 60+ mark, I knew men that worked them.

I quite agree with you that the N & W J class were outstanding examples of easy-breathing locos, regularly achieving 110 mph with 5'10" wheels, but just think of the piston speeds there!

 

As far as the WD 2-10-0 v 9F comparison goes, sure the latter was vastly superior, but since Riddles was involved with both, might there not have been a little connection?

 

Incidentally, I have seen photos of WD 2-10-0 locos in Greece on express passenger duties!

[Michael Edge]

The connection is clearly documented by E.S.Cox and others - as I explained above. Riddles was rather proud of his Austerity 2-8-0 and 2-10-0 designs.

[DenysW]

Inspired by the admiration for the home-grown 9F on these pages as an 'ultimate development', I've put in a bid at an auction for an HO model of a 6,000 hp 4-8-8-2 Southern Pacific cab-forward locomotive. Yes, the real-thing boiler is 10' in diameter (so, just by itself, noticeably  but not hugely over UK loading gauge) and the axle loading at 30 tons is enough to spread the rails and break every overbridge between Derby and London. Yes, I don't have enough track to put it into a train that won't look silly behind it. Yes, I do know that every line the real thing ran on in the UK would also have required re-blocking, re-signalling, massively expanded passing loops, new turning circles, and supplies of bunker-oil.

 

But it will serve to remind me that there are other definitions - from the big wide world  outside the UK - of 'big' and 'powerful' that are not tainted by the suspected involvement of the marketing department (see 'Big Boy') or of 'British is Best'.

[tythatguy1312]

3 hours ago, DenysW said:

and supplies of bunker-oil.

You could reasonably coal-fire a lot of locomotives, even a series of Italian cab-forwards achieved it with cabside bunkers
In fact you could use Vodka to power an oil fired engine... if you wanted a Big Boy to have less power than a Black 5

Edited April 9, 2022 by tythatguy1312

[DenysW]

Southern Pacific might have been able to use vodka, but not coal - illegal in California due to the wildfire risk in the hot dry summers. More theoretically, I think that with 139 sq-ft of grate area, the tender would have to move in front of the cab to use coal, and trigger pretty much a complete re-design. I shudder at the degree of foul language required to maintain a mechanical solid fuel stoking system running the length of even a fairly short locomotive.

[JimC]

I wonder how big the US Mallets would be if you scaled one down to fit the BR standard loading gauge... 

 

I imagine the cylinders might be the main limit since the track gauge couldn't be changed of course. I might go hunting for a scale drawing to try... 

[Flying Pig]

57 minutes ago, DenysW said:

Southern Pacific might have been able to use vodka, but not coal - illegal in California due to the wildfire risk in the hot dry summers. More theoretically, I think that with 139 sq-ft of grate area, the tender would have to move in front of the cab to use coal, and trigger pretty much a complete re-design. I shudder at the degree of foul language required to maintain a mechanical solid fuel stoking system running the length of even a fairly short locomotive.

 

Ok, so put the firebox at the tender end, mechanically stoked.  Gas producer combustion system, modern front end with Lempor ejector or similar and you'd need a door in the side of the smokebox which would look funky (but GPCS reduces smokebox char anyway).  Maybe a 9F-derived 4-10-0?  I doubt it would be worthwhile in real life, but it would make an entertaining model.  I'm thinking Brush 2 cab... possibly another at the rear of the tender for reverse running...  that would require rethinking the control system, so even multiple working might be a possibility...

[JimC]

I didn't feel like spending a lot of time on this, so I grabbed the first dimensioned large US locomotive I found  ( https://en.wikipedia.org/wiki/USRA_Heavy_Santa_Fe ) and did a quick hack of a drawing. It scaled to 80% to fit in the UK loading gauge as shown. I haven't attempted to correct for wheel gauge. Look up what 80% of standard gauge is in 4mm model terms, it might amuse:-)  Anyway that leaves the cylinders at 24" diameter which is surely still too big for the UK gauge, especially so low slung, so this is a very crude approximation.  Driving wheels scaled to about 4'6.

 

I hadn't a readily scaleable drawing of a 9F, so I added a GW 47. As you can see its bigger then any UK locomotive - big surprise as a 2-10-2, but not outrageously so.

Edited April 10, 2022 by JimC

[DenysW]

Quote

Flying Pig said  "... I doubt it would be worthwhile in real life, ..."

Well, on the UK's complex but essentially narrow-gauge system, probably not. We have, to this day, standard-gauge track with a narrow-gauge (compared to Europe and the rest of world) loading gauge. We also have short city-to-city distances meaning that an functional overnight freight service is possible with fairly poor train lengths. Go small engine until the track runs out of slots is not limited to the pre-Grouping Midland Railway and early LMS.

 

And converting from US-loading-gauge (even more generous west of the Mississippi) also probably requires a complete locomotive re-design  (as per JimC, above) as in the UK outside cylinders are limited to 19" (source of assertion: Churchward at an ICE meeting in the time of Edward VII), and the rest of the world are not.

 

Basically, we had a (largely) fit-for-purpose system that we tell ourselves was world-class, and still don't like to be told that we were/are the last major economy to tolerate using toy-scale trains. We didn't change because it was never a good time to spend THAT MUCH money - bridges, stations, embankments, cutting, tunnels, track (including rails & sleeper spacing) and so on.

[PhilJ W]

2 hours ago, Flying Pig said:

 

Ok, so put the firebox at the tender end, mechanically stoked.  Gas producer combustion system, modern front end with Lempor ejector or similar and you'd need a door in the side of the smokebox which would look funky (but GPCS reduces smokebox char anyway).  Maybe a 9F-derived 4-10-0?  I doubt it would be worthwhile in real life, but it would make an entertaining model.  I'm thinking Brush 2 cab... possibly another at the rear of the tender for reverse running...  that would require rethinking the control system, so even multiple working might be a possibility...

If your going to have a cab forward 9F what about carrying the fuel in the space between the frames and the boiler? Relatively easy if you use oil fuel and if burning coal an automatic stoker is a possibility. As for a cab at each end there is the auto trailer technology that can be adopted.

[The Johnster]

4 hours ago, DenysW said:

Well, on the UK's complex but essentially narrow-gauge system, probably not. We have, to this day, standard-gauge track with a narrow-gauge (compared to Europe and the rest of world) loading gauge. We also have short city-to-city distances meaning that an functional overnight freight service is possible with fairly poor train lengths. Go small engine until the track runs out of slots is not limited to the pre-Grouping Midland Railway and early LMS.

 

And converting from US-loading-gauge (even more generous west of the Mississippi) also probably requires a complete locomotive re-design  (as per JimC, above) as in the UK outside cylinders are limited to 19" (source of assertion: Churchward at an ICE meeting in the time of Edward VII), and the rest of the world are not.

 

Basically, we had a (largely) fit-for-purpose system that we tell ourselves was world-class, and still don't like to be told that we were/are the last major economy to tolerate using toy-scale trains. We didn't change because it was never a good time to spend THAT MUCH money - bridges, stations, embankments, cutting, tunnels, track (including rails & sleeper spacing) and so on.

Once the railway network in the UK had substantially developed, say by 1850, with the Stephensonian loading gauge, it would have been hugely difficult to alter the loading gauge.  Anything is possible with willpower, public support, and enough money, but even so...

 

On all existing railways except the GW broad gauge, existing formations would have had to have been widened and heightened, and mostly strengthend to accept increased axle loads.  That's all the cuttings, tunnels, bridges, platforms, loco and goods sheds.  All the overbridges will need rebuilding completely and the approach ramps extended, in the increasingly urbanised areas where new buildings have gone up in the previous decade or two, compulsory purchases will be needed and tens of thousands of homes destroyed, the cost having to be borne by the railway companies, at a time shortly after the Hudson debacle and shortly to endure the Overend Gurney bank collapse that would make it difficult for them to raise new capital amongst the growning middle class with disposable income; their trust in the railways had been damaged, was shortly to be largely destroyed, and has never recovered, which is why taxpayers won't pay for a decent railway system for the next generation.

 

That we saddled ourselves with a restricted loading gauge and built railways with sharp curves, and from that time onwards increasingly steep main line gradients, and have at all times since suffered from short termist approaches to paying for improvements, and at all times before and since consistently demanded a Pullman class railway for parliamentary fares, is beyond argument, but there were and still are very good reasons for this that should at least be taken into account when we castigate the early and mid Victorians for the mess they left us!  Stephenson set the loading gauge by 1830, and it probably looked much bigger than anything that could possibly ever be needed at that point in time, and even Brunel, the go-to 'bigger is better' man of the time, only increased the track gauge, not the loading gauge.  Then we saddled the poor benighted Irish with a better track gauge but the same loading gauge.

 

It took another 120 years for our railways to begin to catch up, until the introduction of the HST, and in many places we are still running services inferior to most developed countries.  Amongst these, only the US and perhaps Canada are lower down the league table in terms of speed, comfort/overcrowding, punctuality, and service levels, and I doubt if there is anywhere where the public perception and opinion of the railway is lower.  Don't be fooled by the 'glory years' between the wars; they were mostly slow, filthy, unreliable, and overpriced.

 

We still have Stephenson's loading gauge, and it is a diffiuclt thing to explain to people who ride on bigger, better, European or Japanese trains who are not railway minded that the time to sort this out was before 1840, and the ship has sailed.   Show them Hitler's Breightspurbahn and they will reckon it was a brilliant idea in engineering terms!

Edited April 10, 2022 by The Johnster

[tythatguy1312]

Looking at how improvements can be made... I'm just at a loss. Logically it would mean an expansion of the pre-existing European Loading Gauge lines which apparently exist near a few ports, but it's taken decades for electrification alone to get this far (not that I've seen a single mile of 25kv AC Overhead myself), yet alone  rebuilding every track on every line on top of hundreds of thousands of buildings & bridges to fit them.

[Flying Pig]

3 hours ago, PhilJ W said:

If your going to have a cab forward 9F what about carrying the fuel in the space between the frames and the boiler? Relatively easy if you use oil fuel and if burning coal an automatic stoker is a possibility. As for a cab at each end there is the auto trailer technology that can be adopted.

 

You need to carry water anyway and its unlikely you could fit decent sized tanks around a 9F boiler (I think we discussed that not too long ago), so if you have the tender anyway it's a more convenient place for the fuel, particularly if using coal.

[PhilJ W]

35 minutes ago, Flying Pig said:

 

You need to carry water anyway and its unlikely you could fit decent sized tanks around a 9F boiler (I think we discussed that not too long ago), so if you have the tender anyway it's a more convenient place for the fuel, particularly if using coal.

Still keep the tender but at the smokebox end, and with a cab for running in either direction.

[tythatguy1312]

10 minutes ago, PhilJ W said:

Still keep the tender but at the smokebox end, and with a cab for running in either direction.

A lower tender, not dissimilar to Big Bertha, might be the way to go instead. Yes it would limit capacity, but that can be offset by sheer length or a raised area between the windows.

[PhilJ W]

24 minutes ago, tythatguy1312 said:

A lower tender, not dissimilar to Big Bertha, might be the way to go instead. Yes it would limit capacity, but that can be offset by sheer length or a raised area between the windows.

Or mount it on bogies like a diesel brake tender.

[billbedford]

8 hours ago, DenysW said:

And converting from US-loading-gauge (even more generous west of the Mississippi) also probably requires a complete locomotive re-design  (as per JimC, above) as in the UK outside cylinders are limited to 19" (source of assertion: Churchward at an ICE meeting in the time of Edward VII), and the rest of the world are not.

 

The GCR 8K 2-8-0s (RODs) and derivatives had 21" x 26" cylinders. 

[The Johnster]

If you want wider outside cyldinders on a 2-cylinder loco within the UK loading gauge and platform clearances, then AFAIK (and if I'm honest I don't K very F), there is no reason that the frames cannot be joggled inwards to accommodated them, in a similar way to the way the inside cylinders are placed on 4-cylinder engines to the de Glehn pattern (Saint/Castle/King/LMS pacifics).  The limiting factor is how much of the cylinder housing you have to have outside of the centre line of the piston, and it's shape; no reason the cylinders can't meet in at the centre line of the loco!

[JimC]

15 minutes ago, The Johnster said:

If you want wider outside cylinders on a 2-cylinder loco within the UK loading gauge and platform clearances, then AFAIK (and if I'm honest I don't K very F), there is no reason that the frames cannot be joggled inwards to accommodated them,

I'm not sure the frames are the limiting factor. Doesn't the piston rod have to be on the centre line of the cylinder? In which case won't the need for the connecting rod and crosshead assy to clear the wheels be a defining factor,  as would the width of the bearings on the coupling rods? I have a table of GW bearing sizes and if I read it correctly on the 47xx the coupling rod bearing on the driving wheel is 4 15/16 long (=wide) and the connecting rod 5 31/32, whilst on the 30xx (ROD) they are 3" and 4 15/16", which it seems to me, if I'm interpreting the table correctly, suggests the ROD cylinder diamter is at the expense of bearing size. 

[The Johnster]

The piston rod is normally coeval with the central axial line of the cylinder as you say, and clearance between the rear, ‘inside’ surface of the crosshead assembly and the  outer face of the leading coupled wheel’s crankpin is a limitation. 
 

But, there is no actual need for the piston rod to be attached to the central point of the piston’s rear face, or for it to be connected directly in a straight line to the crosshead/connecting rod big end bearing; a joggle or connection to another rod connecting to the big end, the slide bars being moved outwards accordingly to increase clearance at the leading wheel’s crankpin. 
 

Now, this probably introduces other problems, stress at the joggle, extra axle loading weight, increased hammer blow because of the greater reciprocating mass, uneven stresses within the cylinder, and is likely more trouble than it is worth, even in Belgium where mad locos are the norm, but might be viable for a loco that needed very big cylinders and did not need to move at any great speed, like a hump shunter. 
 

Steam loco design is a balancing act between the capacity of the boiler to produce steam at a rate higher than the pistons can shove it out of the chimney after turning the wheels with it (which is determined to some extent by the size of the driving wheels), the axle loading, and the loading gauge.  In practice satisfactory (in most cases) locos were built without resorting to my joggles, offset piston rods, or similar jiggerypokery, but my ideas, while they may be unwise for all sorts of sound engineering and mechanical reasons that I do not understand, are theoretically possible. 

 

Being theoretically possible does not not mean that they’d have worked, of course!

[Flying Pig]

3 hours ago, The Johnster said:

But, there is no actual need for the piston rod to be attached to the central point of the piston’s rear face, or for it to be connected directly in a straight line to the crosshead/connecting rod big end bearing; a joggle or connection to another rod connecting to the big end, the slide bars being moved outwards accordingly to increase clearance at the leading wheel’s crankpin. 
 

Now, this probably introduces other problems, strefss at the joggle, extra axle loading weight, increased hammer blow because of the greater reciprocating mass, uneven stresses within the cylinder, and is likely more trouble than it is worth, even in Belgium where mad locos are the norm, but might be viable for a loco that needed very big cylinders and did not need to move at any great speed, like a hump shunter. 

 

Was any kind of steam engine - locomotive or static - ever built with the piston rod off-centre?  I suspect that's asking for a bent piston rod due to the uneven loads and resultant horrible cylinder wear. The severity of the pain would be a function of piston thrust not speed, so not mitigated by the loco being a shunter and made worse by big cylinders.

 

If there was such a beast, it will be documented no doubt at http://www.douglas-self.com/MUSEUM/museum.htm

[The Johnster]

The sort of website that could easily cost me an afternoon, or a weekend...

[DenysW]

Having had a look at loading gauges (and the French 'gabarit' was generally a better search term, although with a tendency to give a lot of canal information in French as well), the UK gauge of 27" on each side of the rails greater than the track gauge (= 110.5" for Standard Gauge) isn't dramatically less than the 124" of the Berne gauge or the US 128".  The UK gauge does reach its maximum width appreciably above track level, which the others don't, and that won't help with cylinder sizes. As JimC noted above, the net effect of the UK/US difference is to reduce the maximum UK boiler diameter to 80% of the US, giving a maximum of 64% of the American area.

 

The Berne height  (14'1") is correspondingly more than the 12'6" of the UK gauge, and so also allows bigger boilers above still reasonably-sized wheels. I have seen comments on the Net that, having agreed to Berne Gauge in 1912, the French Railways still hadn't finished the changes required in the 1930s. The UK hadn't agreed to Berne so hadn't started.

 

What's vastly different with the US practice is locomotive length and axle loading. The Southern Pacific cab-forwards (30 tons/axle) could just squeeze onto a 125' turntable, and the Big Boys needed 135' at 40 tons/axle. Great Western 65', and LNER/LMS 70-75' for WCML and ECML? Use of Mallets also put the front cylinders on the articulated bogie rather than clashing with the frame.

 

The end result of length & gauge differences is the biggest US locomotives (excluding failures like the bendy-boilers, or the Erie triplex) have three times the power of the largest UK ones, and that the UK could have doubled its locomotive power at a noticeable cost in loading gauge expansion, and a huge cost in trackbed upgrades, passing loops and signalling blocks,  and mechanical stoking. It looks like it was never a good time to start spending the money.

[PhilJ W]

20 hours ago, Flying Pig said:

 

Was any kind of steam engine - locomotive or static - ever built with the piston rod off-centre?  I suspect that's asking for a bent piston rod due to the uneven loads and resultant horrible cylinder wear. The severity of the pain would be a function of piston thrust not speed, so not mitigated by the loco being a shunter and made worse by big cylinders.

 

If there was such a beast, it will be documented no doubt at http://www.douglas-self.com/MUSEUM/museum.htm

 

13 hours ago, The Johnster said:

The sort of website that could easily cost me an afternoon, or a weekend...

Indeed it could, and I found this gem, built and used by the GE railway.

http://www.douglas-self.com/MUSEUM/POWER/tower/tower.htm

[Traintresta]

10 hours ago, DenysW said:

Having had a look at loading gauges (and the French 'gabarit' was generally a better search term, although with a tendency to give a lot of canal information in French as well), the UK gauge of 27" on each side of the rails greater than the track gauge (= 110.5" for Standard Gauge) isn't dramatically less than the 124" of the Berne gauge or the US 128".  The UK gauge does reach its maximum width appreciably above track level, which the others don't, and that won't help with cylinder sizes. As JimC noted above, the net effect of the UK/US difference is to reduce the maximum UK boiler diameter to 80% of the US, giving a maximum of 64% of the American area.

 

The Berne height  (14'1") is correspondingly more than the 12'6" of the UK gauge, and so also allows bigger boilers above still reasonably-sized wheels. I have seen comments on the Net that, having agreed to Berne Gauge in 1912, the French Railways still hadn't finished the changes required in the 1930s. The UK hadn't agreed to Berne so hadn't started.

 

What's vastly different with the US practice is locomotive length and axle loading. The Southern Pacific cab-forwards (30 tons/axle) could just squeeze onto a 125' turntable, and the Big Boys needed 135' at 40 tons/axle. Great Western 65', and LNER/LMS 70-75' for WCML and ECML? Use of Mallets also put the front cylinders on the articulated bogie rather than clashing with the frame.

 

The end result of length & gauge differences is the biggest US locomotives (excluding failures like the bendy-boilers, or the Erie triplex) have three times the power of the largest UK ones, and that the UK could have doubled its locomotive power at a noticeable cost in loading gauge expansion, and a huge cost in trackbed upgrades, passing loops and signalling blocks,  and mechanical stoking. It looks like it was never a good time to start spending the money.

Surely with the haul lengths (and shorter trains, in particular freight trains) in the UK, having such large locos would benefit us very little as we wouldn’t be able to utilise them that well?

 

I appreciate trains lengths are somewhat limited by the length of passing sidings, historically speaking, but I would imagine the case for improving those, hence increasing train size would suffer from similar problems of cost because it would inevitably require increased capacity.