Excellent thread!

I hope you come back to Rocket when you discuss its boiler. I remember a school textbook that described most steam locomotives as essentially pre-Rocket or based on the Rocket.

As you say, what went before were clunky, inefficient machines with often bizarre mechanisms. But everything after Rocket was simply an improvement on its fundamental design. Possibly over-egging the pudding a bit, but I think makes a fair point.

Would make a lovely piece for the Journal, you know. 

NeMo

Quote from: Moonglum on December 10, 2023, 09:33:07 AMFantastic reading John, can you at some point please define connecting rods/con rods.

Many thanks, Tim.  I'll describe connecting rods fairly soon.  Unless I divert myself.  And will probably include a picturingham.

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Quote from: Invicta Alec on December 10, 2023, 04:53:43 PMI look forward to learning. I've already picked up a couple of gems of which I had been hitherto unware.

Groovy!  Thank you, Alec.  I'm attempting to include a few gems and, of course, much silliness in these postingtons.  Because 'N' gauge is such fun.

*

Quote from: NeMo on December 10, 2023, 07:02:06 PMI hope you come back to Rocket when you discuss its boiler. I remember a school textbook that described most steam locomotives as essentially pre-Rocket or based on the Rocket.

Thank you, Neale.  I'll most certainly mention Rocket's boiler.  I'd be seriously remis not to.  I agree with the textbook.  To expand slightly - Rocket, Northumbrian, Planet and Patentee.  Robert Stephenson's (who nowadays does not get the recognition he deserves - like Joseph Locke) quartet that set the development of the steam locomotive on sound engineering principles.

By the way, I have another Robert Stephenson innovation, which I think is less well known, coming up.

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Thank you very much, chums, for those kind and encouraging comments.

All the very best.

John

A Coarse Guide to the Steam Locomotive for 'N' Gauge Modellers - Part 4


Hello Chums

More than Six Wheels

During the period from 1840 to 1860, six-wheeled steam locomotives emerged as the normal types.  2-2-2 for passenger trains and 0-4-2 or 0-6-0 for goods.  However, that was also a time of experimentation, with many fascinating variations appearing, which turned out to be evolutionary dead ends.

To my mind, there were two factors which encouraged the development of the mainstream eight-wheeled locomotive.

The Bogie

The first was the patenting of the bogie by William Chapman in 1812.  This simple device, consisting of four wheels, on two parallel axles, mounted on a frame that could pivot, was being used in the Newcastle area for wagons which carried coal.  The term 'bogie' also has a colloquial usage, probably not so common nowadays, as a small-wheeled wagon or trolley.

As far as I'm aware, the first locomotives to move away from fixed frames and having a pivoted bogie was a 4-2-0,  built by Robert Stephenson & Co in 1833, for export to the USA.  Robert Stephenson is credited with the insight that a bogie could be used on locomotives, especially those to be used on lightly-laid and rough track, which was typical of early US railroads.  Its use in the USA became widespread and, in 1840-41, the Birmingham & Gloucester Railway imported 14 4-2-0 locomotives built by Norris of Philadelphia.  Another nine similar locomotives were built for the railway by British firms.

Tank Engines

No, not @Tank , the Locomotive Superintendent of our FabulousForum!  Leaving aside Novelty, which performed badly, albeit to popular acclaim, at the Rainhill trials, early locomotives had a tender behind.  Perhaps I had better rephrase that to say they towed a tender (the name derived from maritime practice) containing coal and water.

There were certain circumstances where the tender was deemed to be rather a nuisance and it was better to carry the coal and water on the locomotive itself.  This is a tank engine.  Not a 'tank', although the erroneous term 'Thomas the Tank' appears to be gaining in popularity.

Some of these were a little bit longer and heavier (carrying all that water) than 'normal' locomotives of the time and, to support the length and spread the weight, various eight-wheeled examples appeared.  Tayleur & Co. built three 4-2-2 tank engines for the Waterford & Kilkenny Railway (No, not a British railway, but instructive) in 1846.  Daniel Gooch designed a class of 4-4-0 bogie tank engines in 1849 for the Great Western Railway (broad gauge of course).

Most importantly, I think, in 1855, Robert Stephenson & Co built five 4-4-0 bogie tank engines for the North London Railway.  These were the first of what became the standard type of passenger locomotive used by that railway company.

*

Bogie Tender Locomotives

Apart from early the examples mentioned, the I believe the first important bogie tender locomotive type was Archibald Sturrock's 4-2-2 bogie express passenger locomotive of 1853 for the Great Northern Railway.  This set a trend which continued as late as 1901 with HA Ivatt's '267' class, also for the Great Northern Railway – the last 4-2-2 type built in Britain.  This type of locomotive, as with the 2-2-2 type, is often called a single-driver or a single.  Nonsense, of course, as they had two driving wheels – one on each side.  But, the terms predated Whyte notation.  I intend to say a little bit more about these later, but let's press on back to 1860.

By then the 2-2-2 was the most common type for fast passenger work, with the 4-2-2 also being used.  However, the 2-4-0, used before then mostly for slower passenger trains, began to take over from the 'singles' on the fast work.  The 2-4-0 slowly became the dominant type for express passenger trains until the 1880s, although some railway companies remained loyal to single-driver types.

Enter the 4-4-0 Bogie Passenger Tender Locomotive.

Just think of the 4-4-0 – alongside the 0-6-0 does it not, in your imagination, typify the 'normal' British locomotives of the late Victorian and Edwardian eras?

What was the first standard gauge British 4-4-0?  Not a trick question, but it was earlier than you might think.  The Stockton & Darlington Railway* had expanded from what we often think of it.  It has rather stuck in the public conscience as it was in 1825. Robert Stephenson & Co built six bogie 4-4-0 locomotives for the Stockton & Darlington Railway between 1860 and 1862.  They were intended for use on the Barnard Castle to Tebay line and, because of the potentially atrocious weather which could be encountered over Stainmore Summit, the first two had commodious American-style cabs and looked remarkably modern.  At the time, a simple weatherboard was deemed more appropriate and the next four were so fitted.

Apart from on the Great North of Scotland Railway, which received its first 4-4-0 from Robert Stephenson & Co in 1861 and ordered no more 2-4-0 locomotives thereafter, it took the 4-4-0 bogie tender engine about 15 years to fully establish itself.

Thomas Wheatley designed a couple of 4-4-0 bogie passenger locomotives for the North British Railway in 1871 and James Stirling introduced his famous '6' class for the Glasgow & South Western Railway in 1873.  SW Johnson produced an elegant 4-4-0 for the Great Eastern Railway in 1874 and followed it up with an even prettier design for the Midland Railway in 1876.  From then until well into the Edwardian era, the 4-4-0 and 0-6-0 pretty much reigned supreme.  Although, of course, there were many locomotives with different wheel arrangements in use.  The final 2-4-0 for a British railway company was built in 1903, by Beyer, Peacock & Co, for the Stratford-upon-Avon & Midland Junction Railway, No. 13 on that line.

The first national 'census' of British locomotive occurred in 1913, courtesy of the Board of Trade's Annual Railway Returns which now included this matter.  The total number of locomotives in use by railway companies was 23,664.  Of these, 7,310 were 0-6-0 tender locomotives and 3,168 were 4-4-0 tender locomotives.  Incidentally, there were 3,700 0-6-0 tank engines.  Which means that 10,478 out of 23,664 locomotives were tender locomotives of 0-6-0 and 4-4-0 wheel arrangements.  Or 44%.

By then, only 955 2-4-0 tender locomotives remained in service and their numbers were in sharp decline.

Can you guess what was the fourth most common wheel arrangement in 1913?  Answer at the end.




[The most common locomotive types for main line work in 1913 - the 0-6-0 for goods or general duties and the bogie 4-4-0 for passenger trains.]


* The Stockton & Darlington Railway was merged into the North Eastern Railway (NER) on 3 July 1863. For legal reasons, it was managed separately as the 'Darlington Section' until 1876, when the former Stockton & Darlington Railway's lines became the NER's Central Division.


'N' Gauge is Such Fun!

Many thanks for looking and all best wishes.

Toodle-oo

John

Answer: The 0-6-2 tank locomotive with 1,395 examples.  Mostly, but not always, a tank engine version of the 0-6-0 goods locomotive.

Hello John,
Wow! This is quite fascinating and I am learning a lot!
Many thanks indeed and please, carry on as much as you can.
Best regards,
Harold

Dugald Drummond, locomotive superintendent of, amongst other railways, the LSWR and Caledonian, is said to have initially declined to design locos with coupled drivers as 'it was like a laddie running wi' his breeks doon..'

But later changed his mind.

Whilst I'm already aware of most of the contents of what you're writing on this thread, I'm enjoying the way it's written. Keep it up!

Martyn

People who call the show "Thomas the Tank" are one of my pet hates. Anyone around me who does is promptly put straight. 

That was a great installment, by the way, John. 

A Coarse Guide to the Steam Locomotive for 'N' Gauge Modellers - Part 5


Hello Chums

Suspension

We'll continue our discussion about frames and wheels in this postington and we'll take a typical locomotive from the end of the Nineteenth Century as our example.




[A North Eastern Railway 'R' class 4-4-0, later LNER 'D20'.  A first-class passenger locomotive with big coupled wheels – 6' 10" diameter.]


The frames are there to hold the locomotive together and all manner of things are attached to the frames.  The frames are made from steel plate and, rather than being simply long rectangles, are shaped as required to allow for the design of the locomotive – for example, they are less high at the front to allow room for the bogie, than they are in the middle.

The frames are joined to each other by means of frame stretcher plates or stretchers, which are vertical fabricated plates or castings at right angles to the frame plates.  These are sometimes solid, but often have a large hole in the middle, to improve access and reduce weight.  Additional strengthening bars, such as Horwich stays, might also be used to make the frames more rigid.  Incidentally, even when fully assembled as a unit, the plural 'frames' is used in Britain.

As you are probably aware, the most common model railway practice is for the axles to revolve in holes in the model locomotive's 'chassis'; sometimes the holes are fitted with fancy bearings (let's ignore sprung or compensated models!).  This is a very simple solution but, unfortunately, won't do for the real thing.  You see, apart from some early 'boneshakers', steam locomotives are equipped with suspension, consisting of springs between the axles and frames.  Which means the axles need to be able to move up and down in the frames.

Blimey – I thought this coarse guide was meant to be simple and we now have a moving axle – or, in the case of that nice shiny locomotive in the picturingham, four moving axles (and that doesn't include the tender).

Let's ignore the springing in the bogie, simply remarking it's like a smaller-scale version of that used for the coupled wheels.  Like in any vehicle with axles, the two axles for the coupled wheels need some sort of bearings to allow them to revolve easily and reliably.  The axle and bearing has a close fit, just sufficient to allow rotation of the axle, so the up-and-down movement required by the springing has to be accommodated between the bearing and the frames.

This was achieved by the bearing being in an axlebox, which looks rather like a metal cube with a big hole through it.  The axle revolves in the hole, with the bearing surfaces lined with 'white metal'* – very similar to the stuff the Union Mills 'R' 4-4-0 is made from.  A steel axle revolving in a soft white metal lining makes for a better bearing than using another hard metal surface.  Let's not get into the metallurgy, but, for so-called plain bearings, a combination of a hard and a soft metal is best.  The axlebox is divided horizontally into halves; both parts are placed around the axle and then held together with big bolts and nuts.

Now for the clever part, the frames have vertical slots called hornguides in them and, with a bit of attention to the bearing surfaces, the axleboxes can move up and down in the hornguides.  To control this movement, a spring – almost always a leaf spring derived from road coach practice, but much bigger and heavier - is attached to the frames and bears on top of the axlebox.

The white metal has a finite life and requires to be renewed from time to time.  If the lubrication fails, friction causes the bearing to heat up and the white metal can melt and run away.  This is what is known as a hot box.  The trick was (and is) to stop before the steel axle is damaged.  Designers did not always pay sufficient attention to having a large enough surface area for the bearing surfaces in the axleboxes, which meant that certain classes of steam locomotives were prone to hot boxes.  The Midland '4F' design is an example of this.  The locomotive was more powerful than its predecessors, but the axleboxes were not given an adequate bearing surface area.




[The picturingham shows a '4F' 0-6-0, a class built by the Midland Railway and perpetuated by the LMS after the 1923 'Grouping'.  Powerful locomotives, they suffered from bearing troubles.  The model is a ProperlyPoole Graham Farish example and runs very nicely indeed with no trace of bearings running hot!  She is about 30 years old.]


The great advantage of this bearing system is that, due to the slots in the frames, a locomotive can be lifted off its wheels so that attention can be given to the bearing surfaces.  Replacing the white metal lining is called remetalling.

Interestingly, Union Mills models use a sort of upside-down version of this system with the axles revolving in a slotted 'keeper plate'.  This allows the axles to move to help cope with dodgy rail joints and suchlike, although they are not sprung.  It also means that a Union Mills coupled wheelset can be taken out in one piece – nifty, eh?




[A Union Mills locomotive (a GWR 'Dean Goods' 0-6-0) from below.  Undoing the two machine screws allows the 'keeper plate' to be removed...}




[... once removed and placed upside down, the 'keeper plate' gives an almost passable visualisation of the side elevation of a locomotive's frames.]




[And here is the wheelset, removed just like the real ones are, albeit they would have had their coupling rods taken off first.  Pressing a wheel onto an axle was a Main Works job, but many steam shed were equipped with lifting gear (or a wheel drop if one is being really fancy) in order to remove a wheelset to give any attention required.]

 
I think, having now made a coarse attempt to describe how a steam locomotive's axles are attached to the frames by means of sprung axleboxes, moving vertically in hornguides, I'll go and sit in a darkened room before inviting you to join me for a discussion of how we can try to arrange to make the wheels go round.  There will be an element of 'it'll never work in theory' about this.

* White metal - an alloy of tin, antimony and copper.  Sometimes a small amount of lead is included.  The ratios of the metals vary according to the intended use.


'N' Gauge is Such Fun!

Many thanks for looking and all best wishes.

Tickety-tonk

John

John,
many thanks for another splendid article on "steam locomotives and how to make 'em" - informative, educational and entertaining as ever!

Best wishes,
Tfc49

Thank you John,

I have finally caught up with the thread having read the first instalment before departing for a alcohol fueled weekend in London.

It became rather impossible to keep following on my hand held mobile communication device with a glass of something in the other hand.

Back up to speed now, please do carry on old chap

Best Wishes
Mike H

PS is Poppy writing these interesting postinghams

Pretty good so far John, although I would like to point out that most locos from the 1920s onward have underslung axleboxes on their driving wheels - in other words, the bottom of the axle box is attached to the spring which in turn is attached to the bottom of the frames.

Regards,

Alex

Quote from: Hailstone on December 12, 2023, 07:46:26 PMPretty good so far John, although I would like to point out that most locos from the 1920s onward have underslung axleboxes on their driving wheels - in other words, the bottom of the axle box is attached to the spring which in turn is attached to the bottom of the frames.

Regards,

Alex

Hello Alex

Thank you very much indeed for this.  I was a tad concerned that the large degree of simplification I was indulging in with these posts might have been an irritation to you and others who have a much better knowledge of steam locomotives that I will ever achieve.

I have been attempting to take a broadly chronological approach and have used typical late-Victorian practice for the last couple of posts.  I am tying myself in knots at present and think I'll need to do another 'frames and wheels' post before I can get on to cylinders, valves and motion.

My plan, if it can be called a plan, is to move forward to just before outside valve gear became commonplace - say about 1910 or so.

Then, later in the series (if I don't give up!), to do several posts under the general heading of 'later developments'.  Outside valve gear, higher boiler pressures, double chimneys (and similar), roller bearings, perhaps manganese linings (but that's maybe going too far for the thread, rotary valve gear and suchlike.  I'll certainly be keen to mention underslung axleboxes then.

As for the original Bulleid 'Pacifics' - I haven't a clue.  They probably would benefit from a series on their own.  And 'Leader' (like Paget's locomotive) I'll leave to someone else!

Thanks, again for your support, Alex.  Every time I see a 'like' from you, I think I'm maybe just about achieving what I set out to do.  And, of course, posts from you for discussion are hugely welcome.

With all good wishes

John     

Really enjoying reading these John, picked up a few bits I still didn't know, keep them coming please!
Steven

I have enjoyed your trip though the development of the steam locomotive, and would like to offer a little information myself. many years ago when I was a member of the locomotive department at Didcot, a book came out which many of us found fascinating and occaisionally useful, it is "Building britains locomotives" by James W Lowe and is still available second hand via Amazon. I still sometimes refer to it.

All the best,

Alex

If the forum is still handing trophies out, this noble gentleman deserves one. 

This 'coarse' guide is actually coming along nicely, John.

For anyone who wants to delve deeper, try 'Locomotives; their construction, maintenance, and operation' by A Morton Bell, in two volumes.

This goes really deep into what the title says, and is very thorough, if a long read.

The first volume is design and construction; the second volume more with maintenance, fault finding, and some theory. There are also chapters on electric and diesel locos, including the Twins.

I've no idea if it is available second hand; my copies are from 1948 and came from a former fireman, later driver, at Colchester shed.

There are other titles available, and Wikipedia has some articles on boiler design.

Martyn