thx712517

I'd like to learn more about the GWR tank engines in general, but a question about the 6400 class in particular. 

As built, the 6400 series had 165 PSI boilers, while the 7400s ran at 180. The following link seems to indicate that the 6400 series was boosted from 165 to 180 in national service (assuming that's what NS stands for.)

http://www.railuk.info/members/steam/getsteam.php?row_id=3087

Is this indeed the case? I'm also confused as to whether they were piston or slide valve as I've seen both mentioned. I assume they were all superheated. What's the best book to look for with good history of the development, design, construction, and operation of GWR tank engines?

Sounds like that LNER 8F wasn't going to be restored any time soon. At least some of her components are going into other locomotives. 

With Brookes No. 1 have they mentioned any change in weight or maintenance? 

5 hours ago, Flying Pig said:

 

If you do anything so heathen may the ghost of Uncle Mort mither you to kingdom come.

Fair enough!

5 hours ago, Flying Pig said:

 

The Belpaire version appears in Andy's post right at the start of the Bachmann radial tank thread, though that isn't the version actually produced.  Coachmann kitbashed one very nicely from a Bachmann model, but sadly I doubt the relevant posts still exist.

 

I prefer the original roundtop engine for appearance. The Hughes version suffers from the rather clunky late L&Y design aesthetic and I don't think it would have been improved by a taper boiler.  For some reason the Hughes engines were on average withdrawn earlier than the originals.

Thank you for that! It's easier to envision a GWR version with that picture. I remember visiting NRM and at the end of the day had a quiet moment standing next to it. Felt like standing next to a pleasant elderly dog. 

I'm curious as to what a L&YR Class 5 2-4-2 would look like, if it had been mildly Swindonized with a Belpaire taper boiler. Apparently there was a Class 6 that featured a Belpaire boiler and superheater, but I've not been able to find a photograph to see what it would look like. 

4 hours ago, Reorte said:

Tornado has a welded boiler although maybe that doesn't count.

Tornado is actually what inspired this question. I recall reading during the boiler test the inspector was quite pleased it didn't leak like old riveted boilers did. I would also assume that welded construction would be stronger and/or lighter than riveted, which would be a plus for lightly-laid heritage lines. 

Have any steam locomotives operating in preservation switched from using a riveted boiler over to a welded one? I assume the cost, engineering, testing, and lack of authenticity are all barriers to such a change. I would assume a welded boiler to be desirable from an operation and maintenance standpoint, although I could be desperately wrong in that regard. 

8 hours ago, The Johnster said:

And there you have the reason it was never done.  There was never really much of a need on the Southern for such a loco; the Kent coalfield managed happily enough with 0-6-0s, and the fast fitted runs on the Western section were in the capable hands of Urie S15s; the Q and Q1s adequately filled any gaps.  The Ashford moguls were much better as mixed traffic locos, in fact as good as any in the country in that role until the Halls appeared.

Too right. Is there an "Imaginary CME" thread here too? If I was in charge of the Southern I'd have my S15 and N, but I need to find my shunting tank still. 

Ah! I misread the nature of the situation then. It's been a while since I last read my Stanier book. So in essence, Stanier and LMS were operating in conditions that Hawksworth later encountered on the GWR postwar as far as poor coal and suboptimal operations? That would explain Hawksworth's adoption of higher superheat then? 

2 hours ago, 62613 said:

You're aware that most of the energy in steam is imparted to it when it changes its state from water to water vapour, i.e the latent heat of vaporisation? Heating the water from ambient temperature to the boiling point for the pressure required adds some energy; superheating adds some more, but not as much as is added when the water is changed to "dry" vapour. You must also be aware that if you expand the steam in a cylinder, it gives back some of the energy as work; not much, I know but some. The effect can be, if the steam is not superheated, but containing water droplets (saturated) If enough energy is taken out, some more of the steam might condense into water in the cylinder. By superheating the steam, enough energy  can be lost without the condensation problem, and it  was found that once you'd done this, there was little point in adding more energy; that is, it was a waste of coal.

Would higher-degree superheat also involve a larger superheater, with the attendant weight penalty?

My understanding is when Stanier went to LMS, his initial designs followed Swindon protocol and included the lower degree of superheat that was the norm. Those locomotives performed poorly in LMS hands, but adopting higher degree superheat resolved that issue. There was also an issue in the design of the King front end and draughting that Stanier had to deal with when he essentially copied that design over to LMS. The restrictions were removed and if I recall he sent word back to Swindon so the Kings could be similarly rectified but nothing came of it. 

I was merely entertaining the idea of GWR adopting the higher degree of superheat that the LMS did as a way to further improve their power.

As to the boiler, what increase in weight would you think result from increasing pressure from 225 to 250, or 250 to 275? I would think at the time the Kings were being designed it would be within Collett's abilities to draw a replacement Castle boiler of higher pressure that could then be fitted to the entire Castle stud. Didn't he do essentially that in converting the Star to the Castle?

My own imaginary locomotives tend more to the internal arrangement than anything external. For example, taking the SECR N class 2-6-0, itself essentially a GWR 43xx, and using it as the basis for freight locomotives on the Southern. Increase the boiler pressure to 225-250 for more power, reduce the coupled wheels to 5' or less for increased tractive effort. Possibly muck about with cylinder bore and stroke as well, upgrading the internal steam passages, things like that. So you've got your 5' drivers for freight, and throw 6' drivers on for a passenger service variant. You'd get two locomotives with majority shared parts and driving style. 

My most visible imaginary locomotive though would be to take the Southern S15 goods loco and replace the round-top boiler with a Lord Nelson style Belpaire and double chimney. For some reason the round-top looks anemic to me. 

Fury puzzles me to no end. They go through all of that complexity and trouble when I would assume a 275-300 PSI conventional boiler would have been far less complex. It was within the state of the art at the time, and I would also assume the weight of a 275 PSI boiler would have been similar or less than Fury's crazy system. Same with LNER's Hush-Hush 10000. Why go to the effort of a Yarrow water tube boiler when you could just crank out a stronger A4 boiler and squeeze it to 300 PSI? 

But it's remarkably easy to armchair decisions made a century ago, especially when viewing it through the narrow goal of improving mechanical performance. US railroads certainly accepted the maintenance of higher pressure boilers but it seems their British counterparts placed a higher emphasis on maintenance cost than Americans did. 

It's like wondering why Churchward didn't make use of much higher superheat temperatures. I could say a modified Castle operating at 275-300 PSI with high superheat (and roller bearings throughout) would negate the need for a King and its associated non-standard components, but at the end of the day the past is the past and cannot be changed. 

I loved going to the 5AT website and reading all the mini articles on various locomotive systems and potential improvements. 

It's not worth a new thread, but why would Collett/Hawksworth/Stanier/Riddles/etc reject roller bearings? I think Riddles did a few Standards with roller bearings and didn't find them worth it, while they were adopted more widely in the US. 

Not sure if this belongs in questions or discussions. I'm curious as to why British locomotives (Grouping to BR) seemed to top out at 250 PSI, while American steam of the same time used 275-300 PSI. Playing with a tractive effort calculator it seems that boosting pressure results in a significant increase in tractive effort. 

Was it the increase in maintenance? Or more expensive material for the boiler? I was thinking about the Castle/King locomotives, where a Castle at 275 or 300 PSI would seem to outperform a King and reduce the need for different locomotive classes. 

Quite a lot of good information. I also remembered to check semgonline.com for their pictures and text. I'm looking forward to my Ivatt/Riddles book for more information. 

I've got an Ivatt/Riddles book by Brian Haresnape on order, but I'd like to know more about the 2-6-2 3MT tank engine. 

Were they truly mixed traffic, hauling both passenger trains and goods trains, or were they primarily used for passengers? Were they used for shunting, or had the diesels already taken that over? 

Did they operate in Wales, or in Scotland? How did drivers and firemen get on with them? Anything you can share honestly, as all I've found so far has been the Wikipedia article and a new-build website that talks about how perfect they are for heritage lines. 

I'm interested in picking up a Bachmann 2-6-2T 3MT tank engine for a shunting layout.

Is the mechanism itself good at low speed back and forth work on DC? I've seen a few videos online but they've been shown more hauling coaches or fresh out of the box with minimal running time. 

Figure when it comes time, I'll grab Peco electrofrog switches and maybe those rail joiners with the power feed coming off them. 

I took the time today to play around with the little pannier. Off with the keeper plate and, yes, the contacts weren't angled out very far. So I gave them a gentle tweak outwards to increase pressure on the wheels. I wiped down the wheel backs with an alcohol wipe, and I gave the gears a tiny little droplet of lubricant since it looked dry. 

With everything back together I gave it a few runs to see how it did and low speed performance does seem to have picked up a bit. Not night and day mind you, but a little better. So I went over the track to make sure it was butted together and tried again. Again, a little better but still occasional stalls on my surplus #4 switches. I ran my hands over them and the frog does seem to be a little higher than the associated rail. 

So, grand test. Put my #6 switches back in, wiped down the track carefully with more alcohol wipes. Pannier runs to the buffers now and reverses without needing a poke. Still the occasional stall in a #6 switch, but not nearly as frequent as before. I think whenever I get the money to try permanently fixed Peco track the stalls will finally be sorted. 

To clarify a few things, 

Yes, the locomotive is OO. It's a Bachmann Branchline 64xx, not Graham Farish. 

The track is HO scale Kato track, with #6 manual points. I live in the United States, but I would assume the product would be available globally. The frogs, from my understanding of the package info, are dead. There are no wires to the points, they just clip into the regular track, and when the switch is thrown (say, to the left) I have a live track in the direction of travel to the left and dead track on the right. 

My diesel locomotive is a bo-bo/4 axle unit rather than a 6 axle, but it is longer by a few inches and substantially heavier than the pannier. I assume it's just heavy and long enough it can't be bothered with any track problems. 

The current setup is an Inglenook layout. Perhaps when I get better at laying track I'll switch to Peco and pinning things down permanently. 

I've got a Bachmann GWR 64xx pannier tank, DC only, running on Kato track with a Kato power supply. It hesitates over my two #6 turnouts, which I assume is a wheelbase issue/size of dead frog and thus not something I can fix. The other problem I have is when reaching the end of a siding if I throttle down and then switch direction on the control pack, the engine won't respond as I open up the throttle again. Sometimes tapping the track (it's snapped together and resting on a table) will get it moving again. I'm not sure why it works up until the point I throttle down prior to switching direction. I don't have these issues with an Atlas GE B23-7 diesel locomotive though, which makes me wonder if it's a locomotive issue or track issue. 

Reading Wardale's book, it seems like a large part of demodification came about due to the one-off nature of the design. There was only one Red Devil, so a rotating pool of drivers and firemen would never really get to know the engine and its quirks. Repairs would be to the prevailing (and at that time declining) standard for the steam fleet.

And yes, I think some of it is due to the finicky nature of the modifications. Wardale may have been better served by mass producing Lempor exhausts for the entire fleet and making that the new standard at overhaul. A few other low-hanging fruits as well and while it wouldn't be as cutting edge as the Red Devil, there could have been wider adoption and improvement of the remaining steam fleet.

As for modern narrow gauge lines modifying and demodifying, I can't say. Maybe lack of specific knowledge, a new cost/benefit ratio, or people didn't like the look of the new stuff cluttering up the lines of the locomotives.

Thanks for the links. I was dimly aware industrial and narrow gauge had been more open to modification and improvement. I wonder why that is, considering that, for example, narrow gauge steam would be more rare than pannier tanks or some other standard gauge loco.

Is it just the cost of adaptation that puts people off? Or do heritage railways attempt preservation as designed for historical purposes rather than performance?

I've heard about and read about the 5AT for a good long while. I was disappointed at its failure to proceed to construction but not surprised. It seems like most heritage railways choose to make use of locomotives near and dear to the region rather than acquire a new build. I admired the 5AT concept mechanically, but aesthetically... 

I noticed the group had reformed as a sort of steam consultant group offering various design improvements and upgrades to existing locomotives which made me wonder if any heritage lines had thought about incorporating new elements to their existing stock. I know Porta had written to the A1 Tornado group with a variety of suggestions but I haven't been able to find what changes, if any, they incorporated into Tornado.