9F Locomotives - Restrictions on Network Rail

Here's a better example. For a description, see the page 77 of: http://www.gracesguide.co.uk/The_Engineer_1880/01/30



Source: https://commons.wikimedia.org/wiki/File:E.B._Wilson_&_Company_locomotive._NER_number_273_(1850).jpg

Tom

 

This one is (I believe) to Bodmer's principles. Crampton's "dummy crankshaft designs which gave such trouble to the L.C.D.R. were (again I believe) single drivers.

Paul H

 

No, it's a Crampton dummy shaft loco. In a Bodmer locomotive, each cylinder has two opposed pistons, each of which is connected via crosshead and crank to the driving axle 180deg out of phase such that the reciprocating masses balance each other. In the loco illustrated, the cylinders are in the conventional position, driving the middle axle as normal, but that axle is devoid of wheels - which was basically the suggestion that started this diversion off.

Re the SER and LCDR single driver dummy-shaft Cramptons: the SER ones ("Folkstone" class, of type 4-2-0) appear to have coped OK with very lightly-loaded trains, to the extent that they remained in service from about 1851 - 1866 before being rebuilt as conventional 2-4-0s, in which form most of them lasted until about 1891/2. The LCDR ones ("Echo" class) were very similar and were built as late as 1862 but were markedly unsuccessful, and they were rebuilt just a year or so later in 1863/4 as 4-4-0s, by the simple expedient of replacing the dummy axle with a conventional wheeled axle, in which form they lasted - give or take the inevitable reboilerings, addition of cabs etc - until the early years of the twentieth century, the last being scrapped in 1906.

Crampton (who was an advisor to the LCDR board) did try to encourage the LCDR to buy some dummy-shaft 0-6-0s (or 0-2-0-2-0, should it be?) similar in layout to the picture above, but Martley (who was the CME, but frequently had to battle for the Board's ear against Crampton) successfully resisted that suggestion and the locos ("Acis" class) were built as conventional inside-cylinder 0-6-0s.

Tom

 

Stand corrected re Bodmer. Martley must have needed all his celebrated sense of humour in dealing with Crampton.

PH

 

Indeed - the LCDR Board seemed to choose wisely in appointing Martley as their Locomotive Engineer, and then put him in a situation of having to endlessly justify his requirements - even beyond the usual financial restraints of that company - by having Crampton engaged as a freelance advisor to the Board with radically divergent views. Despite all that, you could probably make a case that despite its financial poverty, Martley and then Kirtley provided the company with a succession of excellent locomotives: all round the LCDR stock as at 1900 was probably the best in Southern England. Subsequent SECR design under Wainwright was very heavily influenced by LCDR design, married to SER shop practice.

Tom

 

Some how the L.C.D.R. managed to build its carriages from 100% teak which is to the advantage of the I.O.W.S.R to this day.

Paul H

 

Indeed - though I suspect that ensuring a heritage railway had robust carriages 130 years in the future was maybe not a design consideration for them at the time! And, to bring this back on topic, regardless of how much people fret and gnash their teeth, I don't suppose Riddles and his team were especially bothered about whether fitting flangeless drivers to a 9F might cause widespread angst amongst participants in a niche hobby sixty years later...

Tom

 

Agree 100% on both points!

Paul H

 

This axle counter "problem" is a red herring I feel. All that would be needed would be a series of tests to show reliable operation, and to do that all you'd need to do is install an axle counter and evaluator on a heritage railway with a 9F in residence and then run it up and down until you had enough data. The only "problem" as such is that nobody has done this, so nobody will sign off the kit as being compatible.
And even if it doesn't work reliably (though I believe it would; axle counters work on the principle of interrupting an electro-magnetic field for which you don't necessarily need a flange on your large metal wheel), you rather over-state the risk of a wrong-side failure. Worst case scenario is that the flangeless wheel is counted sometimes but not other times; in this scenario imagine a series of axle counters, lets call them A, B, C, D, forming the limits of a series of axle counter blocks, lets call these AB, BC and CD. Now lets suppose axle counter C 'misses' the flangeless wheel as the train goes through, you would end up with a +1 count on block BC and a -1 count on block CD after the train has passed. Neither would show as 'clear' and no following train could approach; inconvenient certainly but not a 'wrong side' failure. Reverse the scenario and suppose that C is the only one which counts the flangeless wheel and you get -1 on BC and +1 on CD, which means that there is a brief moment when BC shows a zero count but only as the last bogie in the train passes through it. I suppose in theory, if the track with the brief zero count was the end of an overlap, this could cause a signal in rear to clear momentarily, but that authority would disappear pretty quickly as the -1 count would put the block into a disturbed state, and even if a train somehow snuck through in this small window of opportunity, it would be stopped at the next signal and the very fact that we have a -1 count tells us that the train we're protecting is now clear of the overlap anyway. The only "collision risk" is if the miscount occurs just as the 9F-hauled train stops with the last wheelset of its train occupying the last couple of metres of an overlap (a place you wouldn't normally plan to stop), and the following train passes a yellow signal in rear then SPADs the red and hits it. Sure, some analysis would need to be done but the combination of unlikely events would result in a miniscule overall risk and even then only of shortening the effective overlap by a couple of metres. I am absolutely certain that this "risk" could be addressed by analysis and risk assessment with no technical solution needed, even if our hypothetical axle counter flangeless wheel trials demonstrate a problem, which I don't think they would.

The raised check rail problem, on the other hand, represents a serious derailment risk and if I was lucky enough to own a 9F I wouldn't go near Network Rail for this reason alone.

 

Continuing off-topic for a moment I did a quick search and came up with the following image of what I presume is a Bodmer locomotive:
http://www.douglas-self.com/MUSEUM/LOCOLOCO/balanced/burchpic1.jpg
(The source page http://www.douglas-self.com/MUSEUM/LOCOLOCO/balanced/balanced.htm states that this is a Burch locomotive so apologies if Bodmer's idea differed somehow!)
I confess I'd never heard of these but it did spark a memory of an opposed cylinder of this type, sectioned, in a museum in Germany. Unfortunately I'd have to find some nearly 20 year old notes to work out which museum. I remember thinking at the time "what a pity they sectioned it" and I can't now remember if it was on a locomotive or literally just a cylinder with two pistons on a display; probably the latter and possibly not even off a loco. Are there any surviving locomotives built on this principle?

 

It is most certainly not a red herring!

Axle counters do indeed work by creating an electromagnetic field that gets distorted - but said distortion is almost entirely due to the wheel flange. The axle or wheel itself make relatively little difference - its the flange that does most of the work in distorting the field in a precise way to achieve a successful count. The big problem is that if the field is not suppressed in a precise and correct manor the system goes to a failed state and requires a reset to clear the section - which in turn guarantees at least one, if not two of the subsequent trains to pass through at caution (done following a collision in the Severn tunnel a few years ago where a section was reset even though it was still occupied by a train).

Thus the risk is not that a 9F might cause an unsafe situation with axle counters - rather its a case it would cause chaos behind it with every single axle counter failing and wrecking the ordinary service.

So I repeat if you want a 9F on the mainline, find a way of fitting flanges on ALL wheels. Without that it will remain prohibited.

 

As I understand it is not quite the same. The Haswell Duplex loco on that page is closer to the Bodmer idea, though using two separate cylinders rather than one.

In a Bodmer locomotive, there are two pistons in one cylinder. The piston at the "back" has a hollow piston rod, and the piston at the "front" has a solid rod that runs through the other hollow rod. So both piston rods emerge from the same end of the cylinder, but move in opposite directions. Each is then attached to its own crosshead and connecting rod, which drive two cranks on the crank axle set 180deg apart. In a two cylinder loco (i.e. with four pistons), the pairs of cranks for each cylinder are then set at 90deg to each other, as is conventional. The effect is that at any one time, the momentum of each connecting rod and piston is exactly balanced by its counterpart which is moving in precisely the opposite direction. From a description I have, there are four valve rods driven by six eccentrics, which I guess makes sense because, in addition to admission of steam at each end of the cylinder, there must also be an admission and exhaust point in the centre that drives the two pistons apart when they are in the middle of the cylinder.

At least two such locos were built for the London and Brighton / South Eastern Railway joint loco committee in 1844; they had two cylinders with 16" diameter and 30" stroke (i.e. two separate 15" strokes in the same cylinder). Supposedly, the one that ended up on the SER was derailed in 1846 and never ran again, being considered a failure (though for some reason it was not broken up until 1880); but the one that ended up on the LBSCR ran until 1874, though it was rebuilt in 1854 and as far as I can tell was fitted with conventional cylinders at that time. The repair and running costs while running in Bodmer form did not bear out the maker's claims for the design.

Apologies for the thread swerve...

Tom

 

No Tom, more interesting than 15 Pages to confirm what we already know about 9f's.

 

If I were to go to the other thread I started 'Gaps in Preservation'

1. We have operational 9F's
2. While it would be nice to have one on the main line, but
a. There are significant practical issues, and
b. They are a single class of loco & the only ten coupled loco in fleet service in the UK
So there must be a question about how historically significant main line operation might be

On the other hand however there were literally thousands of 0-6-0's many of which also worked passenger trains so there might a stronger argument to put a 2251/Q/Q1/4F/whatever back on the main line

 

0-6-0 on the mainline?





Much fun was had by all

 

Was teak the expensive option back then though?

Sawdust.

 

Yes in terms of "price per ton". Yet I am told the L.C.D.R. designs were highly standardised and economical in the amount of wood required. L.B.S.C.R stuff had a more complicated design which required more of "inferior" mahogany. Again, so I am told.

PH

 

The Shrewsbury and Chester had a couple of Crampton 0-4-0s too, these were tender engines which came into GWR stock.

 

There are a number of ways to conclude this discussion.

1 Do not attempt to run a flangelless loco on network rail;
2 Pay for a study to verify if a flangeless loco can run on routes and pay to carry out any remedial work;
3 Pay for a study to verify if machining a flange onto a new tyre on an originally flangeless wheel will allow route access and pay for any additional work recommended.

Have I missed any?