Current and Proposed New-Builds

Is there such a thing as grandfather's rights for a new build to an old design? Even if so, several other things have to change anyway, so the new design as a whole needs to be approved.

 

2968 still has her trapezoidal springs, freshly painted before being refitted! 20 May 2021.

 

The GNR used swing links and appear to have found them to be satisfactory. Patents can be a blessing and a curse and a glance into the activities of James Watt makes for sobering reading in that his actions with regard to making use of what he considered were his patent rights restricted and frustrated engineers who were rather more advanced in their thinking. There were many designs of bogies and trucks and various ideas and options tested out when it came to lateral control. If you come up with a design that you believe will work it is in your own interest to protect that work but not to the extent that Watt did.

Why would someone who wanted a smoother output from locomotive designs choose a four cylinder over a three? Chapelon settled on three cylinders as being the best option and this was not through lack of experience with engines with more. Later LDP settled on three cylinders for high power designs but he also paid a great deal of attention to the two cylinder compound - and I know we are mainly looking at compounds in these examples. Not a four cylinder type in sight. It has been said that once you go beyond two cylinders there is little excuse for not trying a compound and four cylinder compounds were successful for a while but when higher power requirements were needed the three cylinder type was chosen.

It all gets rather involved, load testing was carried out comparing two cylinder types with three, and the turning moment of a four cylinder is pretty much the same as that for a two cylinder, 135 degree crank setting excepted, and conclusions were reached.

Pseudo three cylinder working was tested on four cylinder compounds too. People had questions and went looking for answers. Questions were raised about crank axle strength and the best type to choose with respect to the power output being designed for. It makes for an interesting hobby at the very least.

 

Looking at the GA drawing, I would suggest that the reasoning behind making the frames closer together than the A3s was to be able to fit the poppet valve chambers and especially accommodate the covers, rather than for axle side play which appears to be absolutely minimal on the drawing. Clearances are pretty tight and if you have a look at the cylinder plan view on the drawing I think you will see what I mean. It is all a matter of compromise - especially in engineering!

 

Very long ( by UK Standards) coupled wheelbase and lack of side play does seem to be an odd combination.
How impressive those driving wheels look on the P2, but for the amount of 'racing stretch' on the Aberdeen road surely 5ft 8's would have done...

 

I remember reading elsewhere on this forum that the limitation of the four cylinder compound with inside LPs was the wide spacing of the inside connecting rods and limited space available for the main bearings. Hence the change to three cylinders for the 242 A1. It might have been interesting to see what could have been done on 5' 3" gauge.
I'm also curious to know if anyone attempted to build a four cylinder compound with 135 degree crank setting. Assuming early exhaust release from the HP cylinder, the HP exhaust valve opening would coincide with the LP inlet valve being open, which would have given some sort of improvement.

 

Ireland's loading gauge was only ever a wee bit more generous, side to side, but overall, comparable to the UK height wise. The only carriages ever built to take advantage of the width were the Park Royal laminated body stock (1950s). Loco wise, the 1939 800 class ('Queens') were the only ones to test the envelope and their employment restricted to the Dublin - Cork line (though I believe they were permitted on the line to Limerick).

The principal limiting factor in Ireland was always axle load. Over much of the system, even mainlines were rated 17t and several secondary lines to 14t. Many branches had the sort of restrictions more commonly found in the UK on Col.Stephens lines.

When No.800 Maeve (21t axle load in working order) went north for preservation at Cultra, even in it's empty state, several wagons were employed as 'spacers' to lessen the stress on the bridges of the ex-GNRI Dublin - Belfast mainline.

 

Thankfully this is not an urgent problem for 72010 as they can be fitted quite late in the final build, but there is still the need to solve the problem, and allow mainline use.
No doubt there will be other problems arise as we go on with the construction, I am confident all will be overcome.

 

Progressive hydraulic damping in conjunction with sensors and a computer driven 'management system' as a last resort...

 

An uninformed guess is that it would be worth investigating marine engines to see if they found advantages from that sort of thing. With sustained use at a steady speed my suspicion is they would be the best case for valve timing interaction.

 

I do take your point about donor fatigue. I think that any project needs a unique USP, a Barry wreck which might be associated with a line might well generate more funding than say a new build, but might not against say restoring a loco which hasn't run since the 1980s but which is associated with the early years of the railway. In other words something that makes the engine 'our' engine rather than just another project.

For example while not a pure new build - 35011 gets eyeballs and funding because what they are doing is unique and I think that if it were a more generic 'lets restore a Bulleid' it would get less attention, PR etc. Whereas, 35025 will probably be successfully restored because it is with SLL and they have a critical mass of skills, fund raising etc when it comes to restoring Bulleids, while I'd imagine that 21C123 because of its close association with the early days of the Bluebell will be able to make the most of its 'iconic' status.

 

Indeed yes Monkey Magic. The team behind the unrebuilding of 35011 are doing something similar the GWS with their retro conversion of Maindly Hall into a Saint with Lady of Legend. insomuch as they're returning her [35011] to as built condition with the chain drive valve gear and air smoothed casing.

 

You know? I was just having a think and something came to mind, has anyone thought of newly building a GWR 455 tank?

Especially if you swap between it's GWR and Metropolitain livery, look nice at places such as Didcot, BRC and Epping Ongar.

 

Recent update on the GER F5 coming together at Tyseley, pictures showing the smokebox and bunker fitted to the frames: https://www.holdenf5.co.uk/engineering-news-17th-october-2021/

 

And the NER 0-4-4 coming along as well.

What about some weeks competiton and testing.

Sun ,good food and drink and a lousy job for the poor souls that have to answer the most important question:
What was ,is or will be better; 2-4-2s or 0-4-4s?

 

I'm sorely tempted to nominate Foxfield's sadistic 1:19 ski slope for that purpose!

 

Does that take the record of the fastest transition from suggestion to livery debate?

Tom

 

That was very much the personal choice of each locomotive engineer. At the time of the 1923 Grouping, Britain's main-line railways had 980 2-4-2Ts and 1157 0-4-4Ts.

The 0-4-4T was a very popular type in Britain. The outside cylinder or "Forney type" was also popular for American city railroads, but I do not know of any other country where the 0-4-4T was common.

https://en.wikipedia.org/wiki/Forney_locomotive

 

It would be very interesting to get all the surviving 0-4-4T locos gathered together, so that an informed decision could be made as to which was the second best of them all.

Tom

 

Wasn't the Forney type generally run cab-first, making them a 4-4-0t?