Steam Hoover

I wasn't going to get involved with this thread but here I am....
Proven boiler design gave an efficiency probably about as good as you could get so any improvements have got to be downstream of the regulator. For my two pennyworth I'd be looking at a shaft drive loco and getting rid of coupling rods altogether. Gearbox technology had improved significantly by the late 60's and I'm sure that our gearbox manufacturers could have produced a reliable and robust design suited to the requirements. Put the basic loco on bogies and add chevron suspension, too. The basic steam engine would be a multi-cylindered, short stroke affair on its own dedicated bed frame, probably fitted with roller bearings (but not necessarily). This would allow the bearing design to be dedicated to overcoming the thrust of the pistons. I always thought that early loco engineers had the right approach with this and it was Stephenson and his Northumbria loco design that condemned steam loco technology to having bearings that carried load and thrust for the next 150 years. It might even be a worthwhile thing going back to that early technology and to put the cylinders in the boiler so that they have a steam jacket although it would be a far more complex boiler design to produce.
What else? As I've said, shaft drive would allow bogies and all the advantages they provide. Oil firing would allow operation from remote cabs. The technology already existed in the 60's so there would be no Leader type arrangement with a fireman divorced from a driver and in a remote hot house.
Would all this be possible? I'm not sure!

 

It is like a Heissler or a german diesel-hydraulic.
The first was low rev and no harmonic vibrations.
The second survived harmonics because the Foettinger transformers converted some percents of power to oil heating that had to be cooled away.

 

The 5AT was possible, you wouldn't want to use a locomotive with such a poor power to weight ratio as a black five, they may be the favourite of a number of enthusiasts for ABC reasons etc. but they were an out of date design in world terms, so were nearly all UK locomotives.

 

With the lack of skilled shed staff perhaps a locomotive with improved motion lubrication would help. Higher pressure boiler so a steel firebox. Reduced number of cleaners, so a smooth easily cleaned outer casing. Reduced weight for route availability, so miniaturise the valve gear. Improve the draughting with a multiple jet blastpipe. Three cylinders for power and balance. 6' 2" driving wheels for tractive effort and 24" stroke with large piston valves for high speed.........Well Done Mr Bulleid!

 

The outside cylinders are placed in such a position that they are supported by a very significant frame stretcher which also serves to support the slidebars of the low pressure engine unit. The design layout works very well but you do reach the point where you need a stronger crank axle and this is offered by adopting the three cylinder model; the 240P with its 4,400 hp output is felt to be at the limit before this change needs to be made. The question remains; what would British Railways do with a 4,400 hp locomotive in the 1960s? The French 4-8-0 would out perform any diesel electric or hydraulic that the UK had available in the 1960s, no class 5 diesel can match them for power output, force output yes but there is no escaping the need for power.
The mechanical design of the steam locomotive reached its height in the USA. The engineers there made very much what we might refer to as the right calls when it came to the mechanical side of things, the thermodynamic side is another story.

 

But did an MN have more tractive effort? I know TE isn't everything, but class 40s were a sort-of like for like replacement of the Stanier pacifics, and didn't speed the timetable up, it was the 50s that did that.

It's not (as has been pointed out) sheer top speed, but ability to maintain linespeed up hill and down dale. There's a graph in one of the turbomotive books comparing the speed of a standard duchess, turbomotive and an 86 along the WCML. The 86 is generally a bit faster, but the difference in the slogs up Shap etc are the real differences, so it's ability to pull an extra whack of horsepower out at such times that is the key.

Some interesting blue-sky stuff too. I was assuming keeping it conventional and getting a few incremental gains, but it's always good to see where it goes. For pure blue-sky (ie no need to keep to steam) you'd end up with a class 50 to carry over to electrification.

 

That is rather the point, the extra power was needed, they juat didn't realise it when they ordered a grillion 40/44/45/46s. The 50s were the start of the realisation.
The thing about the Chapelon monsters is whether you could fit them insider British loading gauge and still get the benefits.

 

Been there done that

Viktoria by Hermod posted Jan 28, 2019 at 7:41 PM

Front Krauss-Helmholtz and two compound cylinders inside on second and fourth coupled.

 

Chapelon' engines were not monsters apart from in the performance sense; as for the class 50s 2,700 hp vs 4,400, no wonder the French engineers had to find another 1,000 hp for their new electrics when confronted by 242A1. And the little French man was in no way finished.

 

How about a standard gauge SAR Class 26, should be able to fit within the UK loading gauge

 

Not with 24" bore cylinders

Sent from my SM-A105FN using Tapatalk

 

The restricting UK loading gauge; even the Swiss could accommodate cylinders in excess of 27" bore. You only have so many parameters to juggle with when trying to design a locomotive, talk about making things difficult for yourself.

 

It Is the penalty of pioneering. No one envisaged how railways would develop in the 1820s and 1830s. Even Brunel failed to give sufficient clearance for large outside cylinders when setting out his broad gauge lines but then his understanding of locomotive engineering was poor.

Sent from my SM-A105FN using Tapatalk

 

I like the point that Wardale understood the context in which the steam locomotive operates.

The steam cycle in a thermal power station is well documented, i.e.:-

High temperatures and pressures (sometimes supercritical).
Superheat and reheat.
Condenser.
Multistage feedheating.
Economiser.
Air pre-heating.

and I'm sure there's a lot I've missed out, but a lot of it would just not be practical or maintainable on a locomotive, or otherwise be of limited benefit.

Regarding the French 4-cylinder compounds, it's been discussed elsewhere on this forum that due to the spacing of the large LP cylinders, and the resultant size of the crank axle, the size of the main bearings has to be a compromise. It would be interesting to see what could have been done at, say, 5'3" gauge. I believe that for this reason the 242A1 became a three cylinder machine.

 

In particular, look at the picture of the 240P and imagine lowering the boiler to fit the British loading gauge. There's then no space for the ash pan over one of the coupled axles. You might just sqeeze it in if you split it in two, but even that is dubious. You could of course stick to a Pacific wheel arrangement with a shorter and wider firebox, while keeping the Chapelon front end.

 

The WR would have had Kings to spare with their early replacement by diesel hydraulics. Job done

 

Wasn't that, to some degree at least, down to the available engines? The 55s and 52s were recognition that higher power was desirable but needed two engines to achieve it.

 

Yet Fiennes did realise that power was required, hence the Deltics and experimenting with super power when on the Western.

What I find interesting about this alternative history is the focus on propulsion and speed. What's missing is thought on the parallel investment in the passenger experience that helped change the perspective on the railway at that time. How would steam have supported the transition to electric heating and air conditioning, which slowly led to a much quieter and smoother experience for the vast majority of people for whom travel is not an end in itself?

 

I appreciate the price of pioneering and we continue to pay it. Is it a problem? It depends on what you need to achieve. It certainly restricts some developments.

 

Thanks for your interesting information 242A1!
I am definately not a technical expert as you but I think the Czeck Republic belongs in this category if not above America. The Czeck built some of the finest and most modern steam locomotives in Eastern Europe (possible in the world) such as 498.1, 556.0 475.1 etc. all incorporating several of Chapelons princips.
You mentioned the 141R, but this would`n t fit into the restricted British loading gauge(?)

Knut