U class Versus N class 2-6-0,what's the difference?

You've really summed it up in one sentence. Although I have no experience of a Hall, I do have experience of the others and the S15 will beat the lot, both on haulage capacity and, more importantly, ability to make steam.

How many times have I said this on Nat Pres? Wheel size is irrelevant in terms of hill climbing. It is purely down to tractive effort and ability to produce steam. A steam locomotive produces maximum tractive effort at lowest rotational speed and tractive effort drops off with increasing rotational speed so, in theory, a small wheeled loco is at a disadvantage over a large wheeled one in sustained tractive effort. The only advantage of small wheels is that you can use smaller cylinders to get the equivalent tractive effort at low speed. 60007 will climb Goathland bank just as easily as an S160 because it has a similar T.E. and can produce the steam. Because steam engines have a practical maximum rotational speed, big wheels can let you go faster. They are no bar to going slowly.

 

The S15's have a relatively steep fire grate and no one has problems firing that! Keep the back end full and, if it is throwing hotties at you, you're onto a winner.

 

There are two reasons why on-train catering is important on the NYMR - firstly the length of the line is such that an end to end journey is over an hour and many people don't like to wait that long, secondly the tearooms by themselves are really inadequate for the numbers of visitors if they were the sole providers of refreshments.

 

As is supposed to be said north of the Border "I hear you".

PH

 

Yet another argument for reasonably short run lengths. (Once again the NYMR can justify an exception.)

PH

 

It's pointless quoting loads if you don't quote gradients! The Brighton Mainline has a ruling grade of 1 in 264, with the exception of the initial climb up Grovesnor Bank out of Victoria, which could be banked. 240 tons up a 1 in 264 gradient is an entirely different proposition to the same load up a 1 in 49, or the 1 in 36 of Ilfracombe.

The Maunsell Moguls are very capable locos, and at the time the first N class locos were actually built (during World War 1), were quite likely the most modern and advanced locos in the country. But when all is said and done, they are not especially big, particularly by later standards - however well you fire them, the sustained steaming from a 25sq ft grate is not going to match an S15 with 30sq ft or later, much bigger, pacifics with about 40 sq ft.

Tom

 

Grate area is rarely talked about when people are going on about a locos capabilities but it is one of the fundamentals of loco design, along with tractive effort and speed capability. At the end of the day, for any loco to produce a level of power, it comes back to how much coal it has to burn and this is dependent on grate area and the amount of air that can be pushed through it. A loco with a small grate is never going to be more powerful than one with a large grate.

 

you should really be comparing an S15 to a Grange, not to a Hall.

 

Think about that last sentence. Simple example; a Princess Coronation has a grate area of 50 sq.ft. and there is no way that it can maintain the 4000ihp of a 240P which has a grate area of 40.5 sq.ft. There are many similar examples.

 

I was talking about similar locos with similar efficiencies but I concede your point. Some locos will always be more efficient than others.

 

I dunno, I'm no expert on steam locomotive design, but a fair bit of the above does seem awfully simplistic.

 

For comparison between wheel sizes (and quantity of them as well)as a slight diversion.
How would the S15 compare with Repton on runs up the bank to Goathland?

 

It's fair to say that

It's fair to say that most of what has been said upthread is simplistic, but that would be relative to the fairly simple designs that are being discussed, i.e. the average British steam locomotive of the 20th Century. Want things a little less simple? I refer you to 242A1's post commenting on the comparison between a Princess Coronation and a 240P - a whole World of difference.

Cheers,

Alan

 

I fired 1638 just as badly as I can 847...

 

It's worth seriously considering I think that this movement is principally in the business of pouring tea down people's throats and that running steam trains is an excellent means of getting more people to buy more of our cups of tea.

What we should be considering is the fundamentals of how to maximise teaflow, that being the product of the number of tea drinkers and their individual capacity for tea drinkage.

 

Perhaps this loco used on the East and West Junction Railway between Stratford upon Avon and Towcester in 1876-1878 would be the ideal new build loco for the NYMR?

33.5 sq. ft grate, 38,400lb tractive effort and built in Yorkshire

 

I always wondered how they got away with 22" cylinders. Now I understand - great locos - couldn't go anywhere.

 

Yes, if you take action to minimise the specific steam consumption you just don't need the boiler size. People still believe that the steam locomotive is a simple machine and at one level this might be the case. However achieving the best with the machine in question that is another matter completely. As I have posted before, no one in this country produced a really good design compared with what was achieved elsewhere. There were some good reasons for this but it is regrettable none the less. It is perhaps for the best that some do not appreciate what might be achieved today. Many need their childhood heroes.

 

Presumably the design took account of the lack of platforms and narrow bridge holes in the yards where they were intended to work; all perfectly sensible. But -- how did the railway get them from Eastleigh to Feltham?