A Coarse Guide to the Steam Locomotive for ‘N’ Gauge Modellers

[Newportnobby]

Nice gift, Martyn. Does it explain on the back of each card what the letters denote?

[martyn]

Nice gift, Martyn. Does it explain on the back of each card what the letters denote?

Yes, Mick.

Each card has an explanation on the back. There are a number of subjects; it's not dated, but wagon liveries appear to be the pre-1935 type, and illustrated locos are in Big 4 liveries.

I'll need to go through it a bit more thoroughly!

Martyn

[Train Waiting]

A Coarse Guide to the Steam Locomotive for 'N' Gauge Modellers - Part 10


Hello Chums

After a break to recover, I'm ready for what I thought would be the third part of this little series, but it turns out it's the tenth.  As for its subject matter, let's hear from GJ Churchward:

'The modern locomotive problem is principally a question of boiler.'¹

I suppose, with the fascinating exception of fireless locomotives, the defining characteristic of a steam locomotive is its boiler.  And, as regards time, trouble and expense, the boiler is the critical component of a steam locomotive.

A quotation from LTC Rolt serves to illustrate this point:

'... the heart of the locomotive, the boiler, had been entirely rejuvenated at a cost, as it subsequently transpired, of six hundred pounds.  Truly a magnificent contribution to the railway.²

Boilers had been around for many years, but our story starts in 1802 with Richard Trevithick's  Pen-y-Darren locomotive, generally accepted as the first steam locomotive to run on rails.  This set the overall pattern for the early 'steam dinosaur' locomotives built until 1829 and, in some instances, even later.  These early locomotive featured single flue boilers with the fire at one end and the hot gasses passing from the fire through a flue tube contained inside a horizontal boiler.

The flue was often 'U'-shaped, with the chimney at the same end of the boiler as the fire.  This is called a return flue and allowed the hot gasses to pass twice through the boiler, pretty much doubling the heating surface where the hot surface of the flue was in contact with the water in the boiler.

Return flues were not universally used, for example George Stephenson's Locomotion of 1825 for the Stockton & Darlington Railway used a single through flue of two feet diameter.

These early locomotives had high chimneys to help draw the fire.  Timothy Hackworth's Royal George locomotive of 1827, an 0-6-0, introduced an especially important feature; a blastpipe with a narrow orifice aligned within the chimney so as to use the exhaust steam from the cylinders to help draw the fire through the boiler flue.  The harder the engine worked, the stronger the blast and the more powerful the draw on the fire – a kind of magic.

Typically, these early locomotives had a boiler pressure of 50 pounds per square inch (psi).  This was a significant step forward from the near atmospheric steam pressure used by James Watt thirty or so years earlier.  Watt had declined to use higher pressure steam due to the risk of boiler explosions, given the primitive state of boiler making at the time.  Techniques had improved the intervening years which allowed higher steam pressures to be used.  Albeit, not always safely, as we shall see.





The picturingham shows a replica [note the LNER-style gauge glass] of Timothy Hackworth's Sans Pareil, the original of which was built for the Rainhill locomotive trials of the Liverpool & Manchester Railway in 1829.  This is a good example of a conventional steam locomotive of the time, with its return flue boiler pressed to 50psi.  The fireman stood at this end and the driver was at the far end, an arrangement dictated by the return flue.

Perhaps this is the most convenient time to mention that locomotive boilers are almost always placed horizontally, as seen on Sans Pareil, but vertical boilers have occasionally been used.  Braithwaite & Ericsson's Novelty, also built in 1829 for the Rainhill trials, was of this type.  Vertical boilers were commonplace for other applications for many years, but we won't consider them further.

I have mentioned two of the three Railhill contenders.  The next part will consider the role of the third contender in the development of locomotive boilers. And we will see the contribution made by Messrs Neville and Booth.

¹ GJ Churchward Large Locomotive Boilers paper read to the Institution of Mechanical Engineers in 1906.

² LTC Rolt, Railway Adventure, The Country Book Club Edition, London, 1962, p144.

Mr John Alcock, Managing Director of the Hunslet Engine Company of Leeds had joined the Talyllyn Railway Preservation Society and offered to help get No. 4 Edward Thomas, a former Corris Railway engine, in service.  She was built by Kerr Stuart and Hunslet had taken over the goodwill of that company when it closed.  She returned for the 1952 season.  £600 at 1952 prices would be around £15,000 in 2024.


'N' Gauge is Such Fun!

Many thanks for looking and all best wishes.

Toodle-pip

John

[Train Waiting]

A Coarse Guide to the Steam Locomotive for 'N' Gauge Modellers - Part 11


Hello Chums

It was at  the Rainhill Trials of the Liverpool & Manchester Railway in 1829 that the steam locomotive appeared in pretty much its definitive form with Robert Stephenson's 0-2-2 Rocket.  I said 'pretty much' because it was really his Planet 2-2-0 of 1830 which established the truly definitive form.  However, his Northumbrian 0-2-2, also of 1830, was an important intermediate type as we shall see.

Rocket was the first railway locomotive with a multitubular boiler of the type almost universally used ever since.  Instead of a single large diameter flue of either the through or return type, the boiler contained many small diameter tubes.  Rocket's firebox has been partly opened over the years and the holes for the tubes can be seen easily by an interested observer.  Even with the limitations of my coarse photography, four holes can be seen.



This important development was no more an invention of either George or Robert Stephenson than the blastpipe, which Rocket also had.

I understand the earliest use of a multitubular boiler was made by Mathew Boulton, James Watt's business partner, in 1780.  In this boiler, for a pumping engine in Cornwall, Mr Boulton used copper tubes through which the fire passed.  Mr Boulton did not patent this development and multitubular boilers were subsequently used in other locations in Cornwall.

In 1803, Arthur Woolf, a Cornish engineer, patented a boiler where the water was in tubes with the fire outside – an early use of a water tube boiler.  There were other experimental applications round the same time and, in 1826, James Neville was awarded a patent for a boiler with vertical tubes surrounded by the water, through which the hot gasses from the fire passed on their way to the chimney.

Meanwhile, in 1828, Marc Séguin had obtained a French patent for a multitubular boiler.  However, writing in his book De l'Influence des Chemins de Fer in 1839, M. Séguin admitted that the first application of a multitubular locomotive boiler was on the Liverpool & Manchester Railway.

I think the story becomes interesting because the Rainhill Trials were, in effect, a commercial competition.  The secretary to the Liverpool & Manchester Railway Company was Henry Booth.  From a present-day perspective, one would imagine him to act as an impartial administrator for the Trials.  This does not seem to have been the case.

In fact, it appears Mr Booth collaborated with George and Robert Stephenson on Rocket's design and suggested the use of a multitubular boiler.  It is my understanding that Mr Booth claimed to be unaware of the work of Matthew Boulton or of Mr Neville and M. Séguin's patents.

As can be seen in the picturingham, Rocket had its fire in a separate firebox at the rear of the boiler.  There were four copper pipes connecting the water jacket around the firebox to the boiler to allow for circulation of water.  OVS Bulleid had a similar idea with the thermic syphons fitted to his 'Pacific' locomotive classes built for the Southern Railway about 120 years later.

Northumbrian dispensed with the external firebox in favour of an internal firebox contained within the boiler, rather than as a separate component.  Planet also used this arrangement which became standard practice for locomotive boilers and remains so to the present day.





Incidentally. Rocket's working pressure was 50 psi but the boiler was tested to 150 psi which gave Robert Stephenson valuable experience in the use of stays to hold the boiler in its desired shape.

Having arrived at the modern locomotive boiler as early as 1830, developments occurred gradually over the years.  I will cover some of these, together with an outline description of a typical locomotive boiler in subsequent postingtons.


'N' Gauge is Such Fun!

Many thanks for looking and all best wishes.

Tickety-tonk

John

[Bealman]

Excellent!

[Moonglum]

Fascinating reading John, it is hard to believe that this was all happening 200 years ago!

All the very best,

Tim

[Train Waiting]

A Coarse Guide to the Steam Locomotive for 'N' Gauge Modellers - Part 12


Hello Chums

We have ascertained that the locomotive boiler reached what became its standard form with Robert Stephenson's Northumbrian of 1830.  We also found out a little about the various early experiments with boilers, including Arthur Woolf's 1803 patent for a boiler with water inside the tubes and the fire outside.  We will return to this principle later – it took about seventy years after the appearance of the 'Stephensonian' boiler before the idea of something other than hot gasses in tubes was considered seriously for locomotive boilers.

So, for this part, we'll consider locomotive boilers in the 1830-1900 period and I'll try to stick to British practice.

The picturingham shows a typical late 19th century locomotive – in this case a North Eastern Railway 'R' class 4-4-0 of 1899.





One can see the boiler is horizontally-mounted on top of the frames and its diameter allows clearance for the large coupled wheels, 6' 10" in this case, outside of the boiler.  The end of the boiler nearest the cab contains the internal firebox (just like Northumbrian of 69 years earlier), the middle part is the multitubular boiler and the black-painted part at the front is the smokebox, where the hot gasses from the fire are drawn through the tubes and ejected up the chimney by the action of exhaust steam from the cylinders passing  through the blastpipe – a system we noted was devised by Timothy Hackworth in 1827.

This is what we modellers tend to think of with regard to the boiler, firebox and smokebox, but it really is just the external cladding and paint (SuperSpiffing 'Saxony' Green in this instance) that we are bothered about.  For steam locomotive people, these are the least of their worries.

I thought it might be a wizard wheeze to show you a somewhat similar boiler without its fine outer clothing.  Persons of a nervous disposition (and rivet counters!) are advised to look away now.





Not quite so pretty. Smokebox at the front, complete with its opening door to provide access, multitubular boiler in the middle and the part containing the internal  firebox, called the outer firebox, at the far end.  The internal firebox quickly became known as the 'inner firebox' and we'll use that terminology from now on.

Before closing this part, let's have a quick think about how the boiler is attached to the locomotive's frames.  It's important to remember that the frames are of fixed dimensions but the boiler will expand due to heat.  This expansion must be allowed for or we'll be in lots 'N' lots of bother.

The steam has to pass from the boiler to the cylinders, which are fixed to the frames, and then back to the blastpipe in the smokebox, accurate positioning of which is critical to the performance of the engine.  Therefore, the smokebox end of the boiler is fixed to the frames and all the expansion is allowed for at the firebox end.  You can see the expansion brackets rivetted to the outer firebox sides – the outer firebox fits neatly between the frames and these brackets slide along the top of the frames.





Locomotives with wide fireboxes, over the frames, use a variant of this system.  Well worth looking for the next time you examine a Bulleid 'Pacific'.

**

Please note my flimsy excuse for the more egregious oversimplifications is that these postingtons are in the context of tiny trains with low voltage electric motors and not glorious big, hot steam engines, complete with high pressure live steam [v. v. hazardous].

**

I'd like to record my sincere thanks to the wonderful people at the Lakeside & Haverthwaite Railway who regard my continuing exploration of the nether regions of their lovely steam locomotives with relaxed equanimity.  I commend this line to you, both for the trains and for the bacon rolls, coffee and scones served in Mrs Maher's excellent refreshment room.


'N' Gauge is Such Fun

Many thanks for looking and all best wishes.

Cheerie-bye

John

[crewearpley40]

Thank you John for another wonderful history lesson

[Bealman]

Awesome. I have visited the railway, and the gentleman who showed me around inside was a so enthusiastic, he was almost babbling! But it was great.

Not to be missed. 

[Train Waiting]

A Coarse Guide to the Steam Locomotive for 'N' Gauge Modellers - Part 13


Hello Chums

We have seen a side view of a locomotive's boiler, photographed in the rain at Haverthwaite.  If we nip round the SuperScenic Cumbrian coast far a while we arrive in Ravenglass and, in the Ravenglass & Eskdale Railway's fine new museum, we meet a cutie called Katie.





See what I mean?

Shimmying round we can see the part of her boiler that concerns the enginemen for most of the time.





The firehole door, through which, when opened, the fuel is shovelled onto the fire can be see.  As can these jolly important items, the gauge glasses, which show how much water there is in the boiler.  As a recent reconstruction, Katie has two of these. Please note they have 'zebra stripes' - this was an LNER idea and is pure dead brilliant as they say in a city to the west of here.  Prior to this clever wheeze, an empty gauge glass could be mistaken for a full one with potentially explosive consequences.  Literally.  When viewed through water, the stripes change direction¹, greatly reducing the likelihood of a potentially fatal misreading of the water level in the boiler.

If we move up to a bigger scale – no, we aren't going '00' – we can see the arrangement on a standard gauge locomotive.  In this case, London & North Western Railway 'Precendent' 2-4-0 No. 790 Hardwicke.





She has only one gauge glass – she will also have try-cocks, which later fell out of favour with British railways when two gauge glasses became the norm².  Apart, of course, from on the Great Western.

Her firedoor is bigger than the one we saw on Katie and the two prominent pipes and valve wheels on the faceplate [backhead for GWR people] are for the injectors.  Important things, injectors.  They force cold water into the boiler against the pressure of the steam.  Jolly clever, that.  All done by steam pressure and cones.  Not the seaside sort - they are made, carefully, from metal.

**

¹  Just in case Percy Pedant is about to tell me off, the stripes don't actually change direction, they just appear to do so.

² This took a while.  Here is the incomparable David L Smith writing about the new LMS '3F' 0-6-0T shunting engines which the LMS allocated to the Glasgow & South Western section from October 1924:

'They were truly terrible.  The first thing that caught the eye was the lever reverse; we had had power reverse on our engines since 1875.  There was only one gauge glass; we had had duplicate glasses since 1879.'

 
'N' Gauge is Such Fun!

Many thanks for looking and all best wishes.

Pip-pip

John

[martyn]

I don't know where I read it, and it was a very long time ago, but I'm sure that a piece I've seen said that the injector was originally designed (by Giffard) to refill boilers on a proposed airship!

But that could be a faulty memory......

I don't know if John will cover it, but injectors replaced mechanical pumps, powered usually from an axle or from the valve motion,, which forced water into the boiler. This meant that on occasion, a loco had to be moved just to operate the pump and refill a low boiler. In a terminus this could cause problems, and again, I'm sure I've read in the long distant past that this could mean placing the loco against the buffer stops, applying copious oil to the track, and running at slow speed....

Martyn