Imaginary Locomotives

[rodent279]

The Leyland National prototype was a bit of a lost opportunity, I think. Give it BT10 or class 153/156 bogies, & sliding or plug doors, and with better sound insulation & seats, it would have been a decent replacement for the many Mk1's that soldiered on into the 1990's. I think it was quite a good looking coach on the outside as well, slightly reminiscent of the Doncaster Mk1 prototype E3083, with all those windows.

Could a spare class 153 bodyshell be butchered to make a bodyshell to fit a mk1 underframe?

[PhilJ W]

One of the problems with the Leyland National bodied coach was that it weighed a lot less and that affected its riding qualities.

[JimC]

I had a bit more of a play with the inside cylinder Saint, and drew up the valve gear and cylinders. That was all very well, but that made me realise the front bogie was in the wrong place re the cylinders, so I had to extend at the front (and move the chimney on the smoke box) . Then I realised the brake cylinder was all tangled up in the motion and I had to change the brake setup round , and it started getting difficult. Still not sure that will work. I also gave it a short cone boiler and removed the top feed to make it look more Edwardian. I'm really surprised by how much that changed the appearance. 

Just for a bit more amusement, here's a wire frame of the drawing. Basically the cylinders, motion and (steam) reversing gear are from the City Class, so the valves are under the cylinders, Stroudley style. The drawing I had seems to be for the as built condition with slide valves. Presumably piston valves would have come later. The performance would doubtless have been rather second rate compared to a  real Saint.

 

 

Edited May 19, 2023 by JimC
replaced images

[tythatguy1312]

For as... limited as this would be, I must say it looks stunning. But, in the opposite direction, I can think of a few locos that would've benefited from outside cylinders

[Northmoor]

11 hours ago, tythatguy1312 said:

At this point, in the desperate interest of finding something that hasn't been tried by British rail, how about a British Cab forward? Not something like a J70 or the Leader in which they have 2 cabs, a thoroughbred Cab Forward like those seen on Ferrovie dello Stato Italiane and Southern Pacific.

Since you brought up an alternative to Pacers, how about a 3-bogied articulated version?  It has to be an improvement on 4-wheeled chassis.  Maybe we've already done it on this thread; in fact after over 400 pages, there can't be many concepts that haven't been done at least once.

 

Can we do an electric version of a Class 58?

[PhilJ W]

Just now, Northmoor said:

Since you brought up an alternative to Pacers, how about a 3-bogied articulated version?  It has to be an improvement on 4-wheeled chassis.  Maybe we've already done it on this thread; in fact after over 400 pages, there can't be many concepts that haven't been done at least once.

 

Can we do an electric version of a Class 58?

I did indeed suggest an articulated Pacer some time ago. Though it might have been on another thread.

[rodent279]

1 hour ago, Northmoor said:

Since you brought up an alternative to Pacers, how about a 3-bogied articulated version?  It has to be an improvement on 4-wheeled chassis.  Maybe we've already done it on this thread; in fact after over 400 pages, there can't be many concepts that haven't been done at least once.

 

Can we do an electric version of a Class 58?

An articulated class 153 would make more sense, imho. Though I guess you could still have an articulated 3-axle Pacer.

Though I think Pacers do get a bad press. For what they are designed for, short, high density journeys in the 'burbs, and on gentle secondary branch lines, they are fine. It's when they get used on long distance regional services, like Leeds-Morecambe, or Cardiff-Bristol-Taunton, that they are out of place.

Mind you, bombling along at 60+ mph on the B&E mainline in one was quite an exhilarating experience, though not one I'd be happy with every day, if I was shelling out a couple of grand in season ticket fares.

 

Edited March 14, 2022 by rodent279

[pete_mcfarlane]

On 11/03/2022 at 19:18, JimC said:

I've been trying to sketch out an express Atlantic based on the GWRs notorious Krugers, but I just couldn't make it work. The grate on the Kruger is quite long even though its a wide box, and the whole thing was out of balance. I got this far before I gave it up as a bad loss...

 

You'll notice that various vital components are missing which I hadn't got to before I gave up. Thought I'd post the part complete anyway to provide, hopefully, a smile in times that need them...

One thing for sure, if anything its got even uglier!

 

Replace the front bogie with a single axle, and you've got the GWR take on the French express 2-4-2.

[Miss Prism]

 

This looks a bit too weird for me. GWR saddles are in the middle of the smokebox or (most commonly) towards the rear of the smokebox. Presumably there is some kind of internal smokebox layout reason why this is so? (Position of the cylinder admission ports?)

 

And is there enough room underneath the cylinders for that bogie?  (Compare the front end of 36, which needed dinky bogie wheels.)

 

Scrub that - I can see the similarity to the City layout, but, that said, will the valves be too high in the smokebox? Will the  blastpipe be compromised?

 

Edited March 15, 2022 by Miss Prism

[AlfaZagato]

The outside frame Saint makes me think of what an outside-frame Castle might look like.

 

Were there any UK outside-frame, outside-cylinder locomotives?  Standard gauge, I should mean.   Not uncommon on narrow gauge.

[JimC]

9 hours ago, Miss Prism said:

 

This looks a bit too weird for me. GWR saddles are in the middle of the smokebox or (most commonly) towards the rear of the smokebox. Presumably there is some kind of internal smokebox layout reason why this is so? (Position of the cylinder admission ports?)

 

And is there enough room underneath the cylinders for that bogie?  (Compare the front end of 36, which needed dinky bogie wheels.)

 

Scrub that - I can see the similarity to the City layout, but, that said, will the valves be too high in the smokebox? Will the  blastpipe be compromised?

 

Yeah, grafting the 4-4-0 layout of the leading wheels being driven onto a 4-6-0 chassis is problematic. However laying things out to drive the middle wheels requires more design expertise than I possess. I'm not uncomfortable with having plenty of smokebox behind the saddle - think 4700 in Std 1 boiler form or the Bulldogs with Std 3 boilers, but a forward extension of the smokebox might well have been necessary, it's a good thought.

Valves on the City/Aberdare/Duke series are *under* the cylinders, in what's called the Stroudley arrangement, which leads to rather convoluted and long steam passages but does help with space. It also gives direct drive to both valves and cylinders, rather than indirect via rocker as in the Churchward Standards. The cylinders and valves are not on the same axis, the valves are level in line with driving axle, the cylinders inclined 6 degrees. Now I think of it, I idly wonder if this inspired Holcroft when he pointed out to Gresley that valve and cylinder didn't need to be on the same axis with the centre cylinder of his conjugated gear.

 

Another thought from writing this is that Stephenson valve gear  layout is best with direct drive - valve rod aligned with wheel axle, but Walschaerts doesn't require this. Hence it seems to me that slide valves between cylinders is an ideal layout for Stephensons, but with large piston valves and cylinders I guess it's easier to get a good layout with Walschaerts. The Churchward outside cylinder classes have the complication of rockers to align everything correctly, whilst the 4 cylinders take advantage of the intrinsic properties of Walschaerts (and the scissors gear on 40 was really a Modified Walschaerts) to fit everything in. 

 

Cylinders saddle and chimney are typically vertically aligned on GW 2 cylinder classes and I wanted to follow that pattern, thus cylinders between bogie wheels. 

On reflection I probably should have paid more attention to the layout of the cylinders on the Stars, rather than looking solely at the City for the workings, but the inspiration was the Dapol kitbash. Also the further I go from the Swindon draughtsmen's work the more likely it is that my lack of knowledge and training will result in something ludicrous that could not work, which is a problem for me if not for the topic!

 

Very good  thought provoking post, I fear I've just edited it into a long essay, got me thinking about a number of design issues I hadn't considered before. I hope my guessing/interpretation is reasonable, and I'm not coming up with false speculation. 

 

 

Edited March 15, 2022 by JimC
Edited to add appreciable further thoughts.

[JimC]

2 hours ago, JimC said:

Hence it seems to me that slide valves between cylinders is an ideal layout for Stephensons, but with ...

Which in turn got be thinking about 0-6-0Ts and 0-6-0s on the GWR. The 57xx and the 2251s had slide valves with this layout when built in the 30s, but piston valves had been tried on the 2796 and some of the 2779 lots of 2721 class pannier tank before about 1920. According to RCTS they had exactly the same valve gear as the Stephenson's fitted locomotives, but had the valves on the centre line, one above and one below the cylinders. The steam passages must have looked like a nest of snakes! RCTS says that the valve rods carried arms which provided the offset to the valve spindles. I'm not sure I altogether understand that, whether they were jointed or rigid, but it must have looked rather peculiar. Bet you never realised your Hornby model might have had something so unconventional hidden inside!

 

And this in turn got me thinking about inside cylinders and 0-6-0s and why they survived so long. If you have inside cylinders for the lack of rocking couple and its presumed effect on the track, (I wonder if outside cylinders tended to make already dodgy track worse - that could be a consideration for industrials perhaps?). Why not put valve gear outside to make things easier. But then I wondered, if you did that might some drivers be a bit lazy about big end oil boxes? Dean tried external Stephensons valve gear, internal cylinders on one of his more outre experiments, but it would look bizarre on an inside cylinder locomotive. Do I feel another sketch coming on?

 

[Later] - looked at external valves and gear on a 94 and it doesn't work. Wheels just as much in the way as they would be for outside cylinders.

Edited March 15, 2022 by JimC
Added 'Later' sentence

[Miss Prism]

5 hours ago, JimC said:

 

Valves on the City/Aberdare/Duke series are *under* the cylinders

 

Thanks, Jim. I sort of got my query right in my first version late last night, but then decided I couldn't remember, and changed it to be the wrong way up! Glad to see though it has provoked further thoughts.

[rodent279]

8 hours ago, JimC said:

Yeah, grafting the 4-4-0 layout of the leading wheels being driven onto a 4-6-0 chassis is problematic. However laying things out to drive the middle wheels requires more design expertise than I possess. I'm not uncomfortable with having plenty of smokebox behind the saddle - think 4700 in Std 1 boiler form or the Bulldogs with Std 3 boilers, but a forward extension of the smokebox might well have been necessary, it's a good thought.

Valves on the City/Aberdare/Duke series are *under* the cylinders, in what's called the Stroudley arrangement, which leads to rather convoluted and long steam passages but does help with space. It also gives direct drive to both valves and cylinders, rather than indirect via rocker as in the Churchward Standards. The cylinders and valves are not on the same axis, the valves are level in line with driving axle, the cylinders inclined 6 degrees. Now I think of it, I idly wonder if this inspired Holcroft when he pointed out to Gresley that valve and cylinder didn't need to be on the same axis with the centre cylinder of his conjugated gear.

 

Another thought from writing this is that Stephenson valve gear  layout is best with direct drive - valve rod aligned with wheel axle, but Walschaerts doesn't require this. Hence it seems to me that slide valves between cylinders is an ideal layout for Stephensons, but with large piston valves and cylinders I guess it's easier to get a good layout with Walschaerts. The Churchward outside cylinder classes have the complication of rockers to align everything correctly, whilst the 4 cylinders take advantage of the intrinsic properties of Walschaerts (and the scissors gear on 40 was really a Modified Walschaerts) to fit everything in. 

 

Cylinders saddle and chimney are typically vertically aligned on GW 2 cylinder classes and I wanted to follow that pattern, thus cylinders between bogie wheels. 

On reflection I probably should have paid more attention to the layout of the cylinders on the Stars, rather than looking solely at the City for the workings, but the inspiration was the Dapol kitbash. Also the further I go from the Swindon draughtsmen's work the more likely it is that my lack of knowledge and training will result in something ludicrous that could not work, which is a problem for me if not for the topic!

 

Very good  thought provoking post, I fear I've just edited it into a long essay, got me thinking about a number of design issues I hadn't considered before. I hope my guessing/interpretation is reasonable, and I'm not coming up with false speculation. 

 

 

I *think* I follow.

So if I understand correctly, the relative positioning of piston valves & the associated cylinders, which by the nature of the fact that a piston valve steam chest will be a larger diameter than a slide valve steam chest, means that the cylinder centre line & valve spindle centre line are further apart in a piston valve arrangement that in a slide valve arrangement. This in turn leads to angular irregularities, which are not easily corrected in Stephenson's valve gear, but are in Walschaerts & its derivatives?

Edited March 15, 2022 by rodent279

[JimC]

2 hours ago, rodent279 said:

I *think* I follow.

So if I understand correctly, the relative positioning of piston valves & the associated cylinders, which by the nature of the fact that a piston valve steam chest will be a larger diameter than a slide valve steam chest, means that the cylinder centre line & valve spindle centre line are further apart in a piston valve arrangement that in a slide valve arrangement. This in turn leads to angular irregularities, which are not easily corrected in Stephenson's valve gear, but are in Walschaerts & its derivatives?

Lets see if I can clarify this a bit better... Mind you I am by no means a valve gear expert and I hope for those who are to correct me...
 

I'm not sure angular irregularities is the best phrase. In the case of valve gear discussions that's probably best reserved for discussing the peculiarity that means that 50% of the piston stroke is not 50% of a wheel revolution. What I was talking about was just the relative alignment of piston rods, valve rods and cylinders.

 

Piston rods pretty much must be pointing at the wheel axle no matter what everything else is doing or the relationship between piston stroke and wheel movement gets extremely odd. 

 

In Stephensons in its simplest form you have the valve rod pointing straight at the wheel axle which has the eccentrics on.

So with slide valves between the cylinders the piston and valve rods would all be in the same plane viewed from the side. 

If with Stephensons you can't have the slide valve between the cylinders and all the rods in the same plane (usually lack of space) there are two commonly seen arrangements. 

The Stroudley arrangement, which normally has the valves below the cylinders, has the valves level, and the cylinders inclined by (say) 6 degrees, so valve and piston rods are not parallel. But both are still pointing directly at the axle centre.
The indirect arrangement, as used on the Churchward standards, has the valves above the cylinders and valve and piston rods all parallel and level, but although the piston rods are pointing straight at the axle the valve rods are pointing at a point a good bit above. So in order to have the valve gear working properly the link and eccentrics are effectively inclined (lets say 10 degrees for sake of argument), and drive a lever on a shaft, and the lever at the other end of the shaft can be rotated by 10 degrees to drive the valve rod. 

With Walschaerts there's not the inherent symmetry from two eccentrics. And because there's just one eccentric driving the bottom of the link, the valve rod doesn't need to be aligned to the axle centre, and the way its normally laid out the valve and piston rods cannot be in the same plane.

Does that help?
Maybe this sketch will help too. Most of them are drawn from GW locomotives, but I altered the 15xx Walschaerts for clarity, and the slide valve between cylinders drawing is made up, especially the top view!

 

 

Edited March 15, 2022 by JimC

[Michael Hodgson]

Model in 12" scale of an imaginary train ...

 

 

 

[rodent279]

4 hours ago, JimC said:

Lets see if I can clarify this a bit better... Mind you I am by no means a valve gear expert and I hope for those who are to correct me...
 

I'm not sure angular irregularities is the best phrase. In the case of valve gear discussions that's probably best reserved for discussing the peculiarity that means that 50% of the piston stroke is not 50% of a wheel revolution. What I was talking about was just the relative alignment of piston rods, valve rods and cylinders.

 

Piston rods pretty much must be pointing at the wheel axle no matter what everything else is doing or the relationship between piston stroke and wheel movement gets extremely odd. 

 

In Stephensons in its simplest form you have the valve rod pointing straight at the wheel axle which has the eccentrics on.

So with slide valves between the cylinders the piston and valve rods would all be in the same plane viewed from the side. 

If with Stephensons you can't have the slide valve between the cylinders and all the rods in the same plane (usually lack of space) there are two commonly seen arrangements. 

The Stroudley arrangement, which normally has the valves below the cylinders, has the valves level, and the cylinders inclined by (say) 6 degrees, so valve and piston rods are not parallel. But both are still pointing directly at the axle centre.
The indirect arrangement, as used on the Churchward standards, has the valves above the cylinders and valve and piston rods all parallel and level, but although the piston rods are pointing straight at the axle the valve rods are pointing at a point a good bit above. So in order to have the valve gear working properly the link and eccentrics are effectively inclined (lets say 10 degrees for sake of argument), and drive a lever on a shaft, and the lever at the other end of the shaft can be rotated by 10 degrees to drive the valve rod. 

With Walschaerts there's not the inherent symmetry from two eccentrics. And because there's just one eccentric driving the bottom of the link, the valve rod doesn't need to be aligned to the axle centre, and the way its normally laid out the valve and piston rods cannot be in the same plane.

Does that help?
Maybe this sketch will help too. Most of them are drawn from GW locomotives, but I altered the 15xx Walschaerts for clarity, and the slide valve between cylinders drawing is made up, especially the top view!

 

 

I think I understand better now, thanks. So the offset of the piston valve from the axle c/l is corrected for by the expansion link, & by the angle that it is set at?

[JimC]

17 minutes ago, rodent279 said:

So the offset of the piston valve from the axle c/l is corrected for by the expansion link, & by the angle that it is set at?

The expansion link rocks to and from, its not set at a given angle. There are various videos on youtube which show how it all works, but I didn't immediately spot one I liked. I probably should do an animation of the actual GWR gear, but I haven't the best tools for that. I'm actually struggling to work out how best to explain how I see the design factors. I'm not sure this is the best place either. 

Perhaps some of you folk who work at 305mm to the foot could post links to your Mutual improvement Class material or something of the sort?

 

[eldomtom2]

21 hours ago, Michael Hodgson said:

Model in 12" scale of an imaginary train ...

 

 

 

Well, "imaginary" to me implies something that never existed. Universal Studios' Hogwarts Express funicular is an accurate model of 5972 Olton Hall during its use as a film prop.

[6990WitherslackHall]

2 minutes ago, eldomtom2 said:

Well, "imaginary" to me implies something that never existed. Universal Studios' Hogwarts Express funicular is an accurate model of 5972 Olton Hall during its use as a film prop.

I've seen the real thing 3 times. Twice at the NRM in York: both on display around the Great hall and in steam giving rides. 

The third time was in the Harry Potter studio tour in Watford.

[john new]

14 minutes ago, eldomtom2 said:

Well, "imaginary" to me implies something that never existed. Universal Studios' Hogwarts Express funicular is an accurate model of 5972 Olton Hall during its use as a film prop.

 

Agree. Shame those across the pond see the USA one running (if that's the word) in the getting filthy, uncleaned, state late BR period locos got into; Hogwarts Railways would never tolerate that!

[Hroth]

I thought the mucky state of Hogwarts "Castle" made it look like one of those scrapyard locos that some deluded folk try to sell on ebay...

[Mike 84C]

The point about offset arms to work the valves, visulise two valve rods in parallel, one connected to the motion and one connected to the valve, connected to each other by a clamp block. Only place I have seen it used is under a Festiniog Double Fairlie because room is very limited under a 1-113/4" gauge bogie. They are slide valve operation and the "dummy" valve rod was needed to transfer the movement to the centre of the cylinder block. The valves are side by side in the vertical plane. Hope this helps.

[Mike 84C]

5972 Olton Hall rather a good engine back in the day, as was 6990 Witherslack Hall. I speak from experience of those days!

[The Johnster]

An idea might be to investigate the possibility of developments of the GW 56xx class.  Collett was not averse to messing about with driving wheel sizes or boiler pressure, and a 5'2" driving wheel version (76xx?) might have been a better replacement for pre-grouping South Wales passenger 0-6-2T locos than the BR standard class 3MT 2-6-2Ts that eventually replaced the Taff As and Rhymney Ps, the rebuilt version of the latter giving a very close approximation of what the 76xx might have looked like.  The bigger wheels would have been appreciated for the resulutant increased speed on the faster sections of the Rhymney, and on such main line work as the locos found themselves doing like the Cardiff General-Pontypool Road jobs and main line Summer Saturday reliefs, and would have given the locos a useful bit of extra 'range' from the tanks (actually this would have been offset to some degree by the larger splashers which would have to occupy space inside the tanks) and bunker, and similar differences (or maybe different similarities) existed between the 54xx and 64xx auto-fitted panniers.

 

A problem might have been the pitch of the boiler, which was fairly high on the 56xx as built with 4'7" wheels, and may have brought the centre of gravity up to an uncomfortable level from a ride perespective.  A higher pressure no.2 boiler, as used on the 61xx and 81xx large prairies, might have brought the BR power class up to 6MT, a very creditable amount of grunt for a loco of such restricted dimensions, but I doubt that the extra maintenance and downtime would have made this idea popular with the shed foremen!

 

There is also the possibility of an 0-6-4T version with an extended bunker similar to the 72xx (62xx?) but I can't imagine what work it would be used for.  It might have been blue RA with the extra axle, but this was not important for Valleys work and the blue RA no.2 boilered large prairies were fulfilling that role well enough. in the Valleys and elsewhere.