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

The G16s were indeed one of the widest designs ever to run in this country, at a generous 9'2", the other contenders also being LSWR classes; namely the H16 4-6-2 tank (same family) and the Drummond 4 cylinder T14 (thus proving that having a loco with small cylinders that still fouls everything in sight isn't just a GWR thing). Interestingly, the as-built N15s with 22" cylinders were a svelte 9'1/2", like the rest of the Urie 4-6-0 family, the width of the Urie tanks is actually caused by ... well, the tanks.

The LSWR main line network actually had a very generous structure gauge when it came to width, unlike the Southern system as a whole. H16s were regularly used on ECS moves into Waterloo, race day specials to Ascot, transfer freights to other yards in London and two were transferred to Eastleigh for oil trains. That said, apparently one of them clouted a platform at Waterloo in 1954 and they were henceforth restricted to chimney first movements into the station. However, I would bet no money whatsoever on similar clearances still existing.

A little side note on the power debate.

The N and U have the same boiler, the same cylinders and the same valve gear. Therefore, as much as can be expected between two individual steam engines, they should have the same peak steaming rate and the same peak IHP. The N having smaller wheels is going to do this at 11/12 of the forward speed.

I would expect that running a pair at the same slow speed (like on preserved lines) the N will use less steam for a given power output, because it could be notched up a little further to give the same drawbar pull and work more expansively. At higher speeds, where getting the steam in and out of the cylinders quickly enough becomes the issue, the U will have an advantage through lower piston speed and being less constrained to running at an impractically short cutoff or part closing the regulator to avoid using more steam than the boiler can supply. This generally reflects how the SR used them. Determining what speed the dividing line was found at requires rather more indicator diagrams than I possess.

 

i think one ought to discount for the purposes of staying 'on topic' the S15. the N and U were like the GWR 43XX that Holcroft designed before going to the SECR. a mixed traffic 2-6-0 is always going to be in a different league to a 4-6-0 mixed traffic design. rather like comparing a 43XX to a Grange!

as others have rightly commented the S15 when compared to the N or U had a much bigger boiler and firebox, same as GWR Grange when compared to a 43XX.

cheers,
julian

 

I strongly suspect that back when the railway were common carriers they would have had well practised methods for dealing with out of gauge loads.

 

Fair comment. Lets face it, by and large the railway is run for fun and the catering is run to finance it...

 

Never have more truer words been spoken................

Cheers,

Alan

 

an argument I had recently with someone who thought a particular railway didn't need a café and shop as there were facilities nearby.....!