9F Locomotives - Restrictions on Network Rail

The issue is not so much check rails on curves - it is the wing / check rails provided on points & crossings - without a flange to prevent it the wheel set of the 9f could seriously damage the raised check rail such that a derailment is a real possibility.

I believe all modern pointwork installed over the past three decades or so uses raised check / wing rails which gives you an idea of the scale of the problem.

 

And dont forget flying Scotsman fitted with Cartazzi sliding axlebox and the rest of them to menetion . FISH7373 81C

 

Ordsall Lane, Salford.

 

Thanks for attaching an image of an example of the design detail to be found in today's track work that allows folk to better understand the problem. The driving wheels of the 9f would run on the top of the check rails in order to allow the design to negotiate curves of an acceptably small radius. It is perfectly possible to design a 2-10-0, or a 2-12-0, and have all driving wheels flanged. Thinned flanges are frowned upon too, but avoiding these is all part of the chassis design. There are numerous options when it comes to designing with controlled lateral axle movement. Theses do make the engine more complex.
With the 9f complexity was avoided. It wasn't seen as necessary at the time when these engines were being produced and the simple option of having flange less driving wheels was adequate. If raised check rails were in use in the 1950s you would have a standard class 8 Mikado and not the 9f. Riddles liked things to be simple.

 

*I assume that this refers to the flangeless middle drivers of the 9f as designed, which would run onto a (normal, not raised) check rail instead of hitting it.

Thanks for those posts, which are getting me (and I hope others) closer to understanding the problem.

However the bit that I am still not understanding is why a check rail could be damaged by a wheel striking it, as that is surely what it is there for; to prevent a wheel set moving too far to one side. A check rail serves no purpose unless sometimes a wheel strikes it. A raised check rail that is struck by a flangeless wheel would be struck just the same by a wheel with a flange, would it not?

Is the problem
a) that the absence of a flange on the other wheel of the pair makes it more likely that the check rail can be struck?
and/or
b) that the middle driver of a 9F would hit the rail harder than a typical wheel?

Or what?

None of this is to suggest that NR should relax the present rule but just to help us to understand the reasoning and, perhaps, to indicate what modification(s) would be most likely to allow one of these locos back onto the network.

 

The wheel isn't supposed to 'strike' the check rail, which would introduce shock loadings to both, which neither are designed to withstand. With a conventional check rail on a curve, the check rail itself would start before the curve proper - or the part of the curve it was to protect - when all wheels were still in line. As the wheels travel into the curve, that on the outside tries to move outwards. If that outward thrust is strong enough, the flange will try to climb the gauge face, until that on the inside wheel comes up against the check rail and prevents further outward movement. The contact is gradual and the forces are sliding. It will be realised that, if the loco has a set of flangeless wheels, even the contemporary check rail will have no restraining effect.

In the case of modern switches and crossings, there is no gradual run up to the check rail, and there is a real possibility of violent impact.

 

Please think about it for a moment. A flanged wheel does not 'hit' a check rail, rather the flange slides along the edge of it if necessary - hence the reason the entrance / exit of wing rails are bent inwards.

A flangeless wheel set striking a raised check rail could thus break it or the fittings, damage the wheel any of which present a derailment risk and / or expensive repairs.

 

Do London Underground use these high check rails? If not then maybe a 9F could run from Harrow to Amersham and back.

 

We could paint one in metropolitan red.

 

I'm sure they weren't allowed on the Met/GC in steam days, could be a problem with the curve through Rickmansworth Station

 

As I understand it, Network Rail has for many years been making track more streamlined and curvature less tight for all rolling stock and to improve line speeds.

So if the wheelbase of an all flanged 9F is shown to no longer be an issue (whether through computer analysis or testing), what is to stop any 9F owning group to simply change the tyre on the centre wheelset to a flanged one in order to go mainline?

There are clear benefits to be had for a ten coupled locomotive on the mainline - and don't we have a similarly setup war department 2-10-0 running somewhere with all flanged driving wheelsets?

Surely it's not beyond the realms of fantasy if the desire was there to put a 9F back on the mainline? Granted, not as built, but now suitable for modern running.

The P2 design negotiated less chains than the 9F and is a much bigger locomotive - if the A1 trust can get that locomotive on the national network then a 9F is surely possible? Just a question of desire and money and effort.

 

Sounds a good idea on the face of it. However there are certain issues relating to track off the mainline and crossovers. How many loco yards have tight curves. How many preserved lines have tight curves and crossovers. Fitting a flange to the centre drivers might allow it to go mainline but might preclude it from heritage railways and many yards and even some mainline crossovers. It would be little use modding a 9f for the mainline if it was banned on heritage railways.

 

"Bigger" has sod all to do with anything. The question you should be asking is

(1) What is the coupled wheelbase of the P2
(2) How does that compare to a 9F (or a Stanier 8F which is permitted on NR)

IF the coupled wheelbase of a 9F and the P2 is pretty much identical then it MAY be possible to fit the 9F with flanged wheels throughout - However as others have said that means a new wheelset and the revised setup would still need to be validated and extensively checked in software before it could be trailed physically.

Please note that the A1 trust spent LOTS of time and money on extensive computer modelling and sought permission from NR that the P2 would be compatible with current rail geometry before the cutting of metal started as they realised it was essential to have the support of NR if construction was to go ahead. Any plans to take a 9F back on the mainline require similar levels of involvement, plus a willingness to accept that it may be a suitable solution cannot be agreed and the project cannot go ahead (something the A1 group have been very open about when they first announced the idea to look at the P2 for their next challenge.

 

Thanks for eventually clarifying the question about whether or not NR is open to considering new design proposals. It seems they are from what you say re the P2 so if a body with will and means wanted to get a 9F certified they should be able to do so provided they meet NRs reasonable and transparent requirements?
If NR acts unfairly ie refuses to consider design proposals plus other evidence or makes demands beyond what is reasonable they would presumably be in breach of their constitution?

 

A small caveat if I may to the above response. The coupled wheelbase of the P2 wasn't the main issue. The issue is, was, and remains the combination of a large coupled wheelbase together with a front pony truck AND a cartazzi wheel arrangement. The total length of a P2 is much greater than the 9F and that is the main issue and has always been reported thusly. In fixing the issues the A1 Trust have opted for a different pony truck arrangement to that fitted originally to the P2s.

How on earth did railway companies on the continent and in America manage it with 2-10-2Ts, 4-8-0s, 2-10-4s, 4-8-2s and 2-12-0s with sometimes tighter curvature and some extremely tighter curvature than that seen in this country?

The issue of the 9F seems clear cut to me. Coupled wheelbase has flangeless wheels. Remove flangeless wheels and see if flanged wheels are acceptable. If a similarly sized locomotive (built in this country), the WD 2-10-0, can traverse preserved lines with an all coupled wheelbase then the problems of a 9F with all coupled wheelsets cannot be insurmountable.

 

But we have a number of WD 2-10-0s which are similarly sized that have been able to work well in preservation on a number of preserved railways (and they have an all coupled flanged wheelbase). So is it as insurmountable as it is sold?

 

The coupled whellbase of a 9F is 21ft 8in.(5ft 5in +5ft 5in + 5ft 5in +5ft 5in) The P2 19ft 6in. If equally spaced thats 6ft 6 in x 3.

The flangless driver of a 9F is 10ft 10in from the leading driver. The equivalent point falls between second and third wheelsets in free spaceNegociating a tight curve the 9f flangless will have what should be the flange on the railhead. On the P2 there is no issue as its in free space

 

I am certain that WD 2-10-0s also have flangeless centre drivers, 600 does.

 

You are right, I am talking the proverbial dog's nads there. Just reading on the M&GN site:

http://www.mandgn.co.uk/page.php?pid=36

My apologies gents - carry on!