9F why does not having a flange on the centre wheels stop it being mainlined

1) It would have had problems if fully flanged

2) They are different types of check rails

 

I believe some main line check rails are now higher than the running rails. Therefore a 9F flange-less could hit them on a tight corner.

 

I've just been looking at the Wikipedia page for Chapelon's six cylinder 2-12-0 (translated from French.)

https://fr.wikipedia.org/wiki/160_A_1

I'm wondering whether the "lateral displacement devices" would remove the need for the flangeless centre drivers on the 9F.

 

The link above goes onto the French page

The translated sentence is:-

Due to the length of the machine, the first, fifth and sixth axles were fitted with a lateral displacement device to facilitate enrollment in small radius curves.

 

Unfortunately, as usual, we run into structure gauge issues in the UK. Say you want to allow the coupled wheelsets of a 9F to at least follow the curvature of the track perfectly, even if they're not all perfectly perpendicular to the direction of travel. The most economical arrangement (in terms of the amount of lateral play required) would be to have lateral motion devices (as they were usually referred to in the US, at least) on axles 1, 3 and 5.

A 9F drives on the third axle, so to allow this to happen the cylinders will have to be pushed outwards. Given that the standards all maxed out at 20" cylinder bore, we can then say that for every 1/2" of lateral motion we'll lose at least 1" bore. Drive on the second coupled axle and you may be able to fix the connecting rod, but with the leading axle moving laterally the clearance between the back of the leading crankpin and the connecting rod is going to disappear, so the cylinders need pushing out again and there goes the bore....

The classes I can think of with lateral motion on coupled axles in the UK include the LNER N7 0-6-2T (inside cylinders, lateral play on leading coupled axle), some of the B12 4-6-0s (trailing coupled axle) and LSWR G16 4-8-0T (trailing coupled axle). In all those cases the axle with movement was the leading axle in one direction of travel and didn't foul outside cylinders. Conversely, there's a picture in La Locomotive a Vapeur of the coupled axles of a Union Pacific 4-8-4, showing that only the last axle doesn't have a lateral motion device; such are the joys of a generous structure gauge...

The 9F solution may have been technically quite crude, but it allowed as large a cylinder bore as was reasonably possible in the design envelope.

 

Cast your eye around the World and you will find features included in locomotive design that would never be considered by some designers in the UK, particularly when considering the domestic market. Shortage of finance, shortage of talent, restrictions on loading gauge and axle loading, lack of communication between CME and CCE all of these dictated the nature of the designs produced.

71000, it is generally agreed, owed little to Riddles but was rather the product of Harrison who came from the LNE. Essentially it was an Eastern machine that had the misfortune to be built at Crewe. Riddles liked simple machines and it was pointed out to him that his love of two cylindered simplicity cost steam dearly in the power and efficiency performance stakes.

The 9F technical quite crude? It was bound to be in the circumstances. We never used Krauss-Helmholtz, Schwartzkopff-Eckardt, Zara or Carrelo so far as Bissel bogies go here in the UK. Didn't use axleboxes with spring controlled lateral displacement much either. The 9F could have been produced as a more technically advanced machine. If it had been then this thread would not exist and some of the problems facing current mainline operations wouldn't exist either. The machine that could have been produced could well look rather different to the one that we know.

 

Really? Churchward, Maunsell, Gresley all showing a shortage of talent? What they (and others) all did was what skilled engineers always do: make decisions so as to arrive at the best compromise available within the specific constraints under which they were working. It's a bit pointless bemoaning the relative simplicity of a 9F's chassis arrangements when, as has been pointed out, greater flexibility would have led to compromises in cylinder dimension and therefore available power output.

Even Riddles was working within the constraints of knowing that steam's day's in BR service were strictly limited. In the circumstance, building robust, simple machines that were a bit over-boilered was a sound engineering judgement if your timeframe was that they would likely all be gone within about 15 years.

The one thing that I can guarantee was not a design consideration for any historic CME was building machines of sufficient sophistication to allow continuation of a niche hobby sixty or more years into the future.

Tom

 

And, with hindsight, what a monumental waste of capital that would have been over their eventual working lives!

 

Yet it was a very successful loco class, on both freight and passenger trains.

 

Sorry, waited long enough... wouldn't have been a problem if it had been the 2-8-2design...

 

I sometimes wonder if Chapelon's work on steam passages would ever have found a place in the U.K. if it had not been for the fortunate chance that Gresley and Bulleid spoke French.

PH

 

Quite possibly the case. (Don't forget to edit - I'm sure that you need a "not" in there).

And Tom, I didn't name any individuals and it was interesting that you chose to to select the talent aspect of what is a rather complex mixture of factors. Some engineers made some pretty poor decisions which were not the best compromise that could be reached at the time, Robert Garbe for one.

The design may have been better as a 2-8-2 but that is a new build for the future to test out.

A lesson from some US roads was that fewer locomotives were required given more thought to design and suitable attention to shed facilities. So given an improved design, which would be more expensive in unit cost to build, you would need fewer of them and they would offer other economies.

 

"Not" duly inserted!

Certainly latter day U.S.A. practice (and that of Chapelon/de Caso) impresses in a way that that of the U.K. does not. The work started by H.G. Ivatt to reduce day to day maintenance chores is some consolation.

PH

 

But then it wouldn't have had sufficient adhesive weight, unless of course one had 19 ton driving axles and artificially ballasted pony trucks to keep them on the track putting perhaps 7 or 8 tons on the total weight. Perhaps they should have tried smaller driving wheels, a shorter coupled wheelbase, a shorter stroke and a smaller boiler. Ater all, they were only intended to do 50 mph and the design rather over-achieved this.

 

Or maybe people could stop complaining that a locomotive that was designed 65 years ago and reliably did exactly what it was designed to do, is now no longer suitable to run on the radically different infrastructure of the 21st century!

Tom

 

Could someone post a drawing of a lateral motion device please?

 

This lesson was well known in the UK too - pre-grouping the Caledonian and much-maligned Midland, amongst others, were starting to work on this. Inter-war the LMS invested hugely in improving loco availability with very conspicuous success. However, a more sophisticated loco does not necessarily play well in terms of availability.

Actually started before Ivatt, I believe, although he did prioritise it.
In an earlier period, Crewe, Horwich, Swindon, etc. were highly advanced and at the forefront of developments, always ready to learn lessons from overseas.
One area British railway designs did seem to ignore was developments in British-built export locos from British builders: often more developed/efficient/robust/maintainable than British designs for home use.

 

It depends a little on species. On the coupled axles of a UP 4-8-4, for instance, it's as simple as the axleboxes being allowed side play, which is controlled by dedicated springs or swing links.

On the other hand, for a leading axle on a 2-10-0 or 2-8-2 you might be looking at something like this (DB class 44) or go here and scroll down a lot until you get to the 141P leading truck. Both these attempt to ensure that the leading axle movement is somewhat in tune with the pony truck, thus making the front end behave more like it has a bogie.

To return to my earlier theme, the cylinder centreline spacing on a Class 44 is 2260mm, with 600mm bores for a total width across bores of 2860mm (9' 4.6"), while a 141P has 2230mm cylinder centrelines and 410mm bores for a total width across bores of 2710mm (8' 10.7"). An original LSWR N15, with 22" cylinders (so about as big as ever fitted in the UK) has 2025.7mm centres and a width across bores of 8' 5.75". I assume a 9F is probably narrower than this overall. I've deliberately ignored the thickness of the cylinder casting walls, because it's an independent variable.

Now both those fine European classes would pull anything a 9F could and much more (although dare I suggest the 44 might not have gone quite so fast), but as you can see they'd take a bit of slimming down before they'd fit.

 

Given that Riddles was such a great fan of the German 2-10-0's, particularly the 50's and their austerity version, the 52's, I find it surprising that the 9F's were not built with Krauß-Helmholz front ends; and as for the proposed 2-8-2 version of the 9F, the DRG 41 and the Polish Pt47 2-8-2's have a K-H "bogie"!