Locomotive Front End Designs

I suppose part of the answer is "Why". Tom has identified that coal costs and general efficiency are not especially important for the cost of ownership. What's important is overhaul costs. If you improve the front end so that the coal and water consumption improves it hardly matters. If you improve the front end so that there's more power available don't you risk increasing the overhaul costs? I think I'm right in saying that typically wear and damage occurs disproportionately at the edge of the envelope, so increase the capability and you risk increasing the wear - unless you upgrade everything else to match... So can the improved technology be used to reduce overhaul costs rather than increase power and efficiency?

 

Presumably if you can persuade the crews not to drive it any harder, and traffic not to hang any more on the hook, you will get the efficiency benefit without the damage.

But is it worth it? These aren't payload shifters anymore, but entertainers. The economics are different. Looking the part is as key as efficiency. Can you imagine if Swanage put the T3 out with a double giesel chimney, external feed-water heater and wider firebox on fuel efficiency grounds?

It's not to say that it shouldn't be looked into, and gains incorporated where they can, but the savings in fuel would probably be outweighed by needing one full-time employee to replace a volunteer put off by the new-fangled-ness.

See the continued argument in classic and post-classic bike racing over how much performance-enhancing bits you can add for the difficulties in squaring preservation with technology

 

The 4472/60103 scenario rather proved the point made by some other locomotive engineers and designers in the past and even to this day, names of the usual suspects could follow but I won't bother.
All locomotive designs can be improved. The exhaust system is just one area and the quality of the design of such is viewed as being the very heart of a locomotive, so much so that it has been observed that you should design the exhaust system first and then design the rest of the locomotive around it. The systems fitted were compromised not only because of a lack of understanding but also by a lack of space available to fit a superior system.

As a designer what do you place the emphasis upon, evaporation or specific steam consumption? A boiler not being well driven by its exhaust system is not going to produce its best evaporation rate but you want a higher rate in order to produce the power that you need. So what do you do? Build a larger boiler (and hence probably a larger locomotive) or look at the way that the steam you are producing is being used? Boilers by and large got bigger and exhaust systems remained fairly poor. Who was working on the SSC? Well Chapelon achieved the doubling of a locomotives' power output with a very modest increase in weight. The exhaust system was just one area worked upon, maximising the flow through the steam circuit was another, improved valve design and the application well understood compounding were others.

4472 was improved in a number of areas, it received a double Kylchap exhaust system, larger main steam pipes and a higher working pressure. Chapelon realised that some of the designs he was working on would need some mechanical modifications and strengthening in order to withstand the power outputs that he was predicting.

The A3 needed frame and mechanical improvements too in order to be able to withstand in the long term the impact of the changes that were made and these were not carried out. On balance an investigation of the single chimney and associated exhaust with a concealed improved system fitted within the original envelope would have been a better option. However this would not have served to prove the point in the way that the improvement package did. Locomotives and their designs can be substantially improved. The front end design is important, perhaps the most important but there exists a wide range of other areas that can be reviewed and developed.

Problems arise when you do not address the design as a whole. The fitting of a much improved front end can result in substantial increases in power output, so substantial that they exceed the capacity of the mechanical design of the locomotive to absorb the increase. Those who have built a range of improvements into a design break down the contribution of each improvement to the full figure. It all adds up, exhaust system, enlarged main steam pipes, improved valve and piston design, steam chest volume, adequate superheat temperature, reduced carry over and so on but the end result can be mechanically overwhelming if applied to an existing design.

 

Do you design a locomotive in a vacuum? Or simply because you want to?

Or do you design it to meet a requirement? And if to meet a requirement is that requirement a constant? Do loads increase? Is there a need to move traffic quicker? What are the historic trends and what are the predictions? If you are in the position of holding a monopoly you may be tempted not to invest in any improvements if you can get away with it.

I understand that it was Colin Chapman who viewed an F1 car as only needing to be robust enough to win the race but I don't think that you could apply that thinking to the railways. So how long do you need your locomotive to remain in service for? Is forty years overlong if rising trends would mean that it would be very dated and ineffective by that time when the rising demands placed upon it have totally overburdened it. When a technology is viewed as mature it tends to develop more slowly. Once the steam locomotive became established as a viable technology it progressed rapidly, little point in building too many of a class here or expecting them to last too long either. So when, in the great history of the growth and development of the railways are you designing your engines?

Today, with very few exceptions we are dealing with the question of keeping historical, old established designs working and as far as our railways go we are not engaged in providing a competitive transport service. We are active in a number of areas, heritage, education, leisure; the fact that we trundle around at 25mph is not important. The costs faced in engaging in what we do are another matter.

So can improved detail design reduce maintenance costs? The answer is yes. It next come down to what is acceptable? Some people do not want to change anything. Every detail has to be preserved. Change the exhaust system to allow for improved efficiency, improved power output, ease the demand made upon out part-time firemen? No. Change the piston valve head design to modern multi ring pattern in conjunction with lubrication. Another reversible change. But no, no, no, No, NO! I remember those who argued against feed water treatment. And so it rolls on and on.

If you want to keep your locomotives in their historically correct condition how do you keep them running and control the costs? Or do you give up on the control aspect and get the "begging bowls" out? In the situation that we find ourselves today how do we keep our ever more costly artefacts plying the rails? We cannot rely on the time poor neither the knowledgeable fading generations to do it for us. Should we have more modern designs to do the bulk of the work in order for us to devote more time to the quiet rejuvenation of our more venerable specimens?

Also when it comes to coal and water consumption lowering fuel consumption is more than about simple economics.

 

Isn't one of the goals of the heritage movement to pass on the equipment in proper shape to the next generation?
A better exhaust has water and coal economy as an outcome, but 25/75 mile speed limits and max 11 car loads
will not allow faster travels and heavier trains, so available extra power cannot be used.
I am sure that better coal economy is beneficial to the boiler, its life is determined by the BTU flow it has to endure.
Coal will be scarce in the future whether you believe it or not, governments will restrict its use, and a 15% coal
economy results in a 7th year of free coal.
As for water treatment, the boilers that use it in Holland appear to have tube lifes of 25 years.
Kind regards
Jos

 

I have made this point before but David Wardale pointed out that there are costs associated with coal handling and ash disposal so cutting coal consumption doesnt only save on the coal bill, it saves elsewhere