Wright writes.....

[AndyID]

The 'free gas area' is an aspect of boiler design with no validity for an assessment of power output. 

 

It does relate to power output in so far as it is a function of combustion rate and therefore thermal energy production which ultimately limits power output. Tube area determines the efficiency with which that energy is captured by the water in the boiler.

 

Presumably the engineers applied an assumed constant for the capture efficiency.

[DLT]

 

He brought it along today in bits and between us we got to the stage you see here. Can you believe it? It runs beautifully and what an achievement it'll be when it's finished (he risks further potential extinction in the dismantling of the tender!). Though it would be disingenuous to say I didn't help, he's taken it away for homework and we'll see the progress he'll have made by himself next month.

A brilliant resurrection job Tony.  Please can I ask about the gearbox, is it a Branchlines Multibox?

Many thanks,

Dave.

Edited May 19, 2015 by DLT

[unclebobkt]

Re: the double domes, according to vol 9 of "The Southern Way" - "In 1912 Lawson Billinton took over running the locomotive department and he had his own ideas about the top feed. He had experimented with his 'K' class moguls, the method used here involving a second, forward dome with two high-level clack valves attached to the back."

 

(the high-level clack valves were later removed, but the domes remained, I think).

 

 

 

       Coachman and Barry Ten,

  Thank you both for your replies..

  Being completely ignorant of the original reason for that 'Bactrian.' look my mind would go more with the idea of one of the domes being some sort of top feed rather than a sand-box.

  By the bye - did any British locos. position their sand-boxes on top of their boilers?

        

[Class O]

Yes, the GER did , the decapod springs to mind, there were others as well...

[Mallard60022]

That Pacific, IMO, needs to be renamed Lazarus. Brilliant job.

Tony has seen an old Millholme A2/3 (or that is what it was originally sold as.....  ) that I had part built just to see if I could, having read T's comments about this kit  in his excellent little Loco Kit Building book of some years back. No boast but even I can build stuff better than that EBay heap.

That A2/3 is now in the hands of a local modeller from 36E as he wanted a challenge project; (actually it looked OK but was, as many Millholme  Pacifics, inaccurate). This is/was a horse trade exchange that will result in help with wiring my pointwork (inc double slips) at some later date. Knowing this chap's skills it will look great and run well but I forgot to tell him about the inaccuaracies (tender tank etc). I had replaced the boiler and FB with a DJH one; the original was a lump of ballast.

I wonder if he will read this at some time and maybe post a pic of it?

I reckon it is worth rummaging through stuff 'in boxes under benches' at swapmeets and shows if stuff like this can be found. I've yet to spend time 'rummaging' through the EBay bins.

Phil

[Arthur]

Sandboxes atop boilers were fine where overhead sand filling equipment was common, in the U.S. for example. It was not a popular feature with engine men in the U.K. as buckets of sand had to be hauled up by hand to fill them.

Edited May 19, 2015 by Arthur

[34theletterbetweenB&D]

It (free gas area) does relate to power output in so far as it is a function of combustion rate and therefore thermal energy production which ultimately limits power output. Tube area determines the efficiency with which that energy is captured by the water in the boiler.

 

Presumably the engineers applied an assumed constant for the capture efficiency.

It's a substitute for measuring tube area, and an ineffective one, as it can only be used to compare boilers designed to have the same ratio of tube cross-section to tube area. Since it was M. Chapelon who points this out, I'll take his opinion over the entire LMS steam design establishment.

[Tony Wright]

A brilliant resurrection job Tony.  Please can I ask about the gearbox, is it a Branchlines Multibox?

Many thanks,

Dave.

Thanks Dave,

 

The greatest praise with regard to this 'resurrection' should go to Geoff, not me, for he was the one who dismantled it and made it viable. I've just helped in its rebuilding.

 

As for the gearbox's manufacturer, I'm afraid I don't know. I'd better explain. As is probably realised by now, I have a vast selection of bits and pieces related to the building of locomotives, in particular. You might recall my showing a scratch-built Ivatt 4MT which I completed some little time ago in these pages, the property of Richard Wilson. Included in the box containing the part-finished loco were loads of parts for a BR Standard 4MT 2-6-0 chassis, including this gearbox. Apparently, Richard had been to a Missenden weekend where he'd attempted to build the 4MT's chassis under the guidance of Iain Rice. The motive power was ostensibly the two-stage motor/gearbox seen installed in the A1. Quite why such a hefty combination was recommended in a modest-boilered 2-6-0, I can't say, but it certainly would have been a too-tight fit in my view. Not only that, it sounded like a chain saw in operation and was way too-tight. I dismantled it, adjusted the bearings, reassembled it and put it to one side for potential future use, fitting a much more appropriate SE Finecast combination into the Ivatt 2-6-0 in exchange. 

 

It could be a London Road Models' two stage 'box but it doesn't have any etched identification on its frames. Originally, we installed it driving off the centre axle but, as is almost expected now, it was quieter in reverse, though visually very smooth. Turning it round did the trick - so much so that it's quiet and smooth both ways now. 

[peach james]

Ah, that is interesting again. The 'free gas area' is an aspect of boiler design with no validity for an assessment of power output. Reduction ad absurdum: put a single huge flue through the boiler of enormous area and the calculated power increases. The success of the Stephenson locomotive was the adoption of a smaller flue area subdivided over many tubes, to effect better heat transfer and thus power genration capability.

 

Interestingly, a form of this very experiment was performed inadvertently on the C1, which was preserved with the boiler in final condition, but with the superheater elements removed. When returned to steam for run specials, it wouldn't steam. The solution was to insert unused supeheater elements in the superheater flue tubes, reducing the free gas area. Then it steamed...

 

Used as a multiplier, it does have some validity.  By experience, a Free Gas Area of 14-15 % (14.8 is what I used the last time I set out a boiler design), is usually about best.  A higher FGA than that results in an inefficient, but free steaming boiler.  (and my traction engine is proof- the smoke box gets to 900F or hotter- enough to slag aluminum).  There are practical limits to this- trying to get enough tubes into a small boiler to get a 14% free gas area can be problematic, because of wanting the tube diameter from all obstructions (edge of tube- edge of barrel, or adjacent tube).  What using FGA*grate area will do is give a decent approximation of boiler HP.  It's not going to be exact, but for the purposes of overall power output, it will be good enough.  Could the C2's been downgraded deliberately ?  Most likely, for the reasons outlined above, that they were clapped, and there was no intent to fix them at that point, so they were deliberately de-rated to prevent some clown slapping one on the front of an express and expecting them to keep time. 

 

At the upper limits (above 900, in the formula), the grate limit is not the issue, but the fireman is.  So far as I have seen, the unofficial number used in the UK was 2500 lb/hr of coal for the fireman, which results in power outputs of less than 2000 BHP being reliably possible.  If you stick a 2nd fireman on, then the DBHP available from a Duchess goes up quite a bit.  I understand most of the really high power output #'s recorded, were done with 3 on the footplate taking turns- passed fireman, driver and loco inspector.  The amusing part is that the Austerities were the only class in the UK to have stokers...for a "small" freight engine !

 

James Powell

[Arthur]

No Austerities had stokers, they were a utility design after all. Three (I think) 9Fs were fitted with Berkeley mechanical stokers. They were of limited use in that under UK conditions locomotives rarely need full power for extended periods. There are periods of reduced demand giving respite to both fireman and boiler. Terry Essery gives an account of firing one on a Saltley Carlisle freight. They really needed a crushed coal to work, such coal was often not available in the hurly burly of everyday shed life. He spent more time in the bunker, breaking up the big lumps so that the stoker would work, than he did on the footplate.

 

The Duchess is the one UK class generally accepted at being at the limits of hand firing and in most other countries a locomotive with a grate of that size would have been so fitted. Because of the nature of UK operations, as outlined above, hand firing sufficed, just, for day to day use. They did have coal pushers fitted to bring the coal forward as the trip progressed.

Edited May 19, 2015 by Arthur

[Porcy Mane]

No Austerities had stokers,

Pedant Mode On

 

Hunslet Austerity 3890 (Technically the last SG steam loco built in the UK prior to That A1 thingy.) was fitted with an underfeed stoker. Worked at Cadeby Colliery.

Hunslet 3193 was another.

 

Pedant Mode Off

 

Porcy

Edited May 19, 2015 by Porcy Mane

[Arthur]

 

I damned well knew that was gonna get a mention!!

[Porcy Mane]

I damned well knew that was gonna get a mention!!

Sorry. Couldn't resist it...

[peach james]

Some of the LD Porta modified ones had them...for smoke control reasons.  It is kind of funny that a 49 ton, 0-6-0, had a stoker fitted, when the largest express locos in the UK which _should_ have had stokers fitted didn't.  The other option of putting on a 2nd fireman would have also worked, but would have cost (ukp) to implement, and as mentioned, the engines were barely, but able to complete the regular work they were scheduled for.  Because of freight timings, they were less needed on freight workings- the demand for HP in the UK on freight workings is much lower than North America or South Africa. 

 

http://www.martynbane.co.uk/modernsteam/ldp/austerity/portaausterity.htm

 

James

[AndyID]

It's a substitute for measuring tube area, and an ineffective one, as it can only be used to compare boilers designed to have the same ratio of tube cross-section to tube area. Since it was M. Chapelon who points this out, I'll take his opinion over the entire LMS steam design establishment.

 

No disagreement with M. Chapelon, nor am I defending the LMS method. My only point was that the FGA must be sufficient to support the combustion necessary to achieve the desired power output, and I doubt M. Chapelon would have disagreed with that either.

 

(BTW - isn't it usual to indicate when a quotation has been edited?)

[34theletterbetweenB&D]

...(BTW - isn't it usual to indicate when a quotation has been edited?)

Sorry about that; forgot the ellipsis.

 

No disagreement with M. Chapelon, nor am I defending the LMS method. My only point was that the FGA must be sufficient to support the combustion necessary to achieve the desired power output, and I doubt M. Chapelon would have disagreed with that either...

Indeed not, but the grate area is the determinant of what is required, in both air admission to support full combustion, and the passage of combustion gas, if the boiler is properly designed; so FGA does not need to appear as it is a restatement of grate area! Grate area is the fundamental measure of the capabilty to boil water, if all else is equal in the quality of the boiler design. What should substitute for FGA in the calculation is a factor proportional to superheater ratio, as this is where further energy is added to the steam. When it is considered what performance gain is observed (with no change in net FGA by alteration of the flue arrangements) from a saturated loco's performance by the addition and increase in size of a superheater it is very strange that this is omitted from a power assessment system! The remaining significant factors are 'bundled' in the tractive effort estimate - again with the assumption that the design quality is equivalent or nearly so.

[Tony Wright]

All this 'hard sums' stuff about steam loco power is way above my head, so I'll not even presume to comment.

 

 

The prototype of this, of course, was driven by a diesel engine. It's Heljan's latest 7mm RTR offering, to be reviewed next month in BRM. It looks great in my view and it runs very sweetly (driven by electricity). 

Edited May 20, 2015 by Tony Wright

[Tony Wright]

 

Also electrically-driven, the almost complete Brassmasters' 0-8-4T in EM. Just a few bits to do now - steps, pipes, guard irons, etc. It, too, will feature in BRM before long. 

 

I mentioned 'hard sums' in my last post. This, I think, is the metalworking equivalent!

 

Edited to ask a question. Since no tank fillers are provided for the top of the side tanks, I assume that the filler in the bunker space was the sole one. Am I right in this assumption, please? 

Edited May 20, 2015 by Tony Wright

[Andy Reichert]

Even though I train spotted in the late 50's and early 60's, somehow I never got to love 1:1 scale steam locos close up. My leanings were always to EMU's.

 

I think I have more instinctive admiration for quiet, invisible, almost unlimited power, smoothly controlled by turning a simple knob or lever.

 

Andy

[John lewsey]

Hi these photos are useful to me as I'm building a 2mm model so please keep them coming

Regards

John

[t-b-g]

Pedant Mode On

 

Hunslet Austerity 3890 (Technically the last SG steam loco built in the UK prior to That A1 thingy.) was fitted with an underfeed stoker. Worked at Cadeby Colliery.

Hunslet 3193 was another.

 

Pedant Mode Off

 

Porcy

 

Double pedant query mode on......

 

Somebody once told me that the only true Austerities were produced during the war and anything before or after was just an industrial tank and not a true Austerity.

 

I don't know if that is right but I throw it into the melting pot to run it up the flag pole to see if the idea has legs.

 

Tony

[jwealleans]

I like your out of the box thinking, Tony. Once I've got my ducks in a row and leveraged my paradigm, I'll draft up a response.

 

Meeting bingo, anyone?

[LNER4479]

Can I bag the 'low hanging fruit' one? Always makes be smile that...

 

Tony - I don't know whether it's a trick of the light or not but in the prototype picture of the LNWR 0-8-4T that your model version is sat on it looks like someone has painted the wheel centres a light grey or yellow colour?(!) Not unlike the poor old compound that was thus disfigured for its last duty Daily Mail Andy Capp special...

[Jol Wilkinson]

I think you are, the water being carried by those rectangular section balancing pipes across the car doorway. The LNWR was a pretty crude outfit despite calling itself the Premier Line. How do you plan to fill the wheel spokes with balancing Tony....?

I think that all the side tank LNWR locos had the bunker filler and trunking to the side tanks.

 

Of course, one man's crude is another person's efficiently simple.

[coachmann]

Of course, one man's crude is another person's efficiently simple.

Climb aboard a Coal Tank and I'll bet you won't consider it an efficiently simple task haha....

 

Almost forgot to comment on that 7mm Railcar.....It's a stonker!

Edited May 20, 2015 by coachmann