I remember paperback versions of Tom Rolt's 'Red for danger', and I also have 'Highland railway'; 'Speed records on British railways'; were they Pan? I may have had others, but they have been disposed of after disintegrating after many years use  .

I didn't read Hamilton Ellis, but I did read many of OS Nock's books, and distinctly remember ordering 'Britain's railways at War' from our local library when it was first released.

CJ Allen's 'The Great Eastern Railway' was another early buy, and I only re-read it about a month ago. He, of course, worked for the GER and later, LNER.

Looking forward to compounding, John.....

Martyn

A Coarse Guide to the Steam Locomotive for 'N' Gauge Modellers - Part 75


Hello Chums

More Than Two Cylinders - 3

In this part we'll discuss standard gauge¹ steam locomotives with more than three cylinders. We might reasonably assume that will mean four cylinders.  Let's get the exceptions out of the way so we can proceed on that basis. Mr Bulleid's 'Leader' class 0-6-0+0-6-0 for the Southern had six cylinders - three on each power bogie. In a moment of corporate insanity, five locomotives were authorised but only one completed. A deeply flawed solution in search of a problem. Allegedly intended to replace aging 'M7' 0-4-4T locomotives, the solution was surely for Mr Bulleid to copy what his his brother-in-law, Mr Ivatt the Younger, was doing on the LMS and build really good, modern tank engines - 2-6-2T or 2-6-4T.

Also with six cylinders is a one-off, but a successful one. The LNER 'U1' 2-8-0+0-8-2 Garratt, intended for banking duties in the West Riding.

Finally, an eight-cylinder locomotive - yes, you read that correctly - the Paget 2-6-2. Cecil Pager was was Works Manager of the Midland Railway's Derby Works. Officially, the project was his own private one, but the locomotive was built at Derby and the Midland ended up contributing £2,000 in order that it could be completed. The locomotive emerged from Derby Works in February 1909, as Midland No. 2299. It ran tests, but never entered service. The project was abandoned by 1913.





I know this seems an unlikely tale, but mentioning that Mr Paget's father, Sir Ernest Paget, was Chairman of the Midland, might help explain the unusual circumstances. Incidentally, Cecil Paget was promoted to the post of General Superintendent of the Midland, where he introduced a traffic control system. He had distinguished military service during the Great War, rising to the rank of Lt-Col and being awarded the DSO.

**

Having dealt with the oddities - always such fun - let's see what was happening at Kilmarnock, in my native Ayrshire, in the spring of 1897. Since 1892, James Manson, the Locomotive Superintendent, had provided the Glasgow & South Western Railway (G&SWR - always with the ampersand) with some conventional but excellent 4-4-0 locomotives for passenger duties. In a break from the tradition of the Stirling brothers and Hugh Smellie (pronounced 'Smiley' by the way) these had rather magnificent domes atop their boilers.

Then, in April 1897, Mr Manson gave those interested in British locomotives a surprise - the country's first four-cylinder simple expansion engine, No. 11 on the G&SWR. She looked like a member of the elegant '8' Class with the addition of outside cylinders and connecting rods. She was allocated to Carlisle steam shed and placed on top passenger duties - the 'Pullman Link'.





Unfortunately, she was not a complete success, being heavier on coal and water than the '8' Class engines also in the Pullman Link. Some claimed this was due to the additional demands for steam from her four cylinders, but the cylinder volume exceeded that of the '8' Class by a proportion of only 1.05 to 1.

It's always a pleasure to quote from the writings of the incomparable David L Smith; here he is on No. 11:

'They could not get it 'on the beat', a sine qua non with G&SW engines. It did its work, and ran its time, but they did not like it. When the first 4-6-0s came out in 1903 No. 11 became a sort of spare, sometimes doing station pilot work at Carlisle Citadel.'²

This suggests No.11's valve setting wasn't quite right. Incidentally, two sets of inside Stephenson link motion were provided, the valves for the outside cylinders being driven from the inside motion by rocking shafts passing through openings in the frames.

No. 11 was extensively rebuilt by Mr Whitelegg, the G&SWR's last Chief Mechanical Engineer, in late 1922. Little of the original was left apart from the wheels. Numbered 394 and, in a break with long-standing G&SWR tradition, named Lord Glenarthur after the company's chairman, the engine performed well on the Glasgow to Ayr services until 1931. After that, she was used on local work until withdrawal in November 1934.

The next four-cylindered locomotive appeared from the LNWR's Crewe Works a couple of months after No. 11 entered service. Like No. 11, she was a 4-4-0, LNWR No. 1501. This engine was a member of a class of compound locomotives, but altered to simple-expansion with a view to comparing her performance with that of compound locomotives. The boiler had insufficient capacity to supply four 15 inch high-pressure cylinders and the engine was subsequently altered to a compound.

Later in 1897, Dugald Drummond on the L&SWR introduced the first of six four-cylinder locomotives of the unusual 4-2-2-0 wheel arrangement. These engines had no coupling rods; the two inside cylinders drove the leading driving axle and the outside cylinders drove the rear driving axle - 'double singles' if you like.




 
Unpopular with the enginemen, these engines weren't particularly successful and spent a lot of time under repair. The Southern wasted little time in condemning them and all were gone by 1927. Still, they were Mr Drummond's first foray into four cylinders and worse was to follow. Much worse.

**

Which brings us to a new century and a new monarch - to the Era of the Big Engine.

You might have noticed that this ultra-brief mini-series has a particular appreciation of the work of certain locomotive engineers, including Mr Ivatt - both of him. The next interesting development with four-cylinders occurred in Coronation Year - 1902 - when Mr Ivatt the Elder had built another of his '990' Class 'Atlantics' for the Great Northern. Later, these came to be called 'Small Atlantics'³ and Henry Oakley is part of the National Collection.

No. 271 differed from the other Great Northern 'Atlantics' by having four cylinders, all driving on the leading coupled axle. As for her performance, it is good to be able to quote Mr Ivatt's grandson:

'Ivatt soon reached the conclusion that any improvement was marginal and certainly did not justify the extra cost, complication and maintenance.' ⁴

Later in the same year, No. 251, the first of Mr Ivatt's 'Large Atlantics' emerged from Doncaster Works. Like the '990' Class, she had two cylinders. She also had a boiler of 5 ft 6 in diameter. A Big Engine, indeed. And an exceptionally good one.

**

The period from King Edwardian VII's Coronation to the Grouping in 1923 saw several locomotive engineers designing 4-6-0s. In my view, one of these designs was excellent, a few were good and many were no improvement on the 4-4-0s which they were intended to replace. Some were downright awful - we've already heard about the three-cylinder Caledonian '956' class. But, here, we will restrict our discussion to those with four cylinders. There's normally no need to go into detail regarding each class - an overview grouped by railway will suffice to give us a flavour of what these locomotives were like.

Great Western Railway 'Star' Class of 1907.

The shining star [Thank you!] in the firmament of four-cylinder locomotives. Mr Churchward's cross of USA and French practice combined with excellent Swindon detail design and workmanship produced a winner. Later enlarged as the 'Castle' and 'King' classes, locomotives to this basic design were built into the BR era. It would take a much better writer than me to do justice to the excellence of a 'Forty'. The enginemen loved them. In my view, their only competitor for the best British four-cylinder design is Mr Stanier's mighty 'Princess Coronation' class for the LMS.

Incidentally, the origin of the 'Star' class can be traced to three French 4-4-2 locomotives which Mr Churchward persuaded his Board to purchase. We'll discuss this when we finally get on the the part/s about compounding. Obviously, I'm engaging in delaying tactics as a volunteer to write these still has not emerged. Even although Bribery by Chocolate is on offer.





The picturingham shows GWR 'Star' 4-6-0 No. 4000 North Star. She was a very interesting engine, being built as a simple-expansion 4-4-2 in April 1906. She was No. 40 and soon named North Star. We'll discuss her performance compared with the French compound locomotives later. However, Mr Churchward was well aware that the adhesive weight of 55 tons as a 4-6-0, rather than 39 tons as a 4-4-2, would be jolly handy in sorting out the ferocious Devonshire banks. That's the steeply-sloping kind, not the money-lending kind, although they were, in all probability, ferocious as well.

Which meant he standardised on 4-6-0s for express passenger work, with the exception of The Great Bear four-cylinder 4-6-2 of 1908.

Thirty production 'Star' Class 4-6-0s, derived from No. 40, were put into service from February 1907. Once these were complete, No. 40 went into Swindon Works and emerged converted into a 'Star' and numbered No. 4000.

Her history doesn't end there because, in 1929, Mr Collet had her rebuilt as a 'Castle' - this happened to some of the 'Stars'. She kept her name and number and gave excellent service until withdrawn in May 1957. How the Great Western's shareholders must have given nightly thanks to this magnificent locomotive. BR, not having shareholders, was possibly less appreciative of her work. And what work it was - 2,110,396 miles run during her life of over fifty years. The highest mileage of any 'Castle', although, of course, she had a good head start on the others.

Although a 'Castle' was superior for all-out performance, in other circumstances some enginemen had a soft spot for a 'Forty' in good order as they were exceptionally free-running locomotives.  The late Kenneth H Leech, a professional railwayman and authority on GWR locomotives, explained why.

The 'Stars', as built, had 14 1/4 in diameter cylinders with 8 in diameter piston valves. The 'Castles' had the same-sized valves with 16 in diameter cylinders which could reach 17 in on final rebore.

'By modern standards the steam and exhaust ports were on the small side [for the 'Castles'' cylinders] and tended to restrict free running.'⁵

**

There we are, from the mixed experience of the first British simple-expansion four cylinder locomotives to Mr Churchward's SuperSpiffing No. 40 and the many magnificent engines derived from her. In the next part we'll discuss how other locomotive engineers fared with their designs of four-cylinder engines.

Hardly a cliff-hanger. More like an absolutely level-hanger.

Lots 'N' lots of footnotes this time. I wouldn't want you to think I make all of this up. I just make most of it up.


¹ As far as I'm aware, the first four-cylinder locomotives to run in Great Britain were articulated engines of Robert Fairlie's design for the Festiniog Railway.

² David L Smith, Locomotives of the Glasgow & South Western Railway, David & Charles, Newton Abbot, 1976, ISBN 0 7153 6969 1, Page 92.

³ Such was the pace of steam locomotive development at the time. When introduced in June 1898, much was made of No. 990 being the largest and heaviest express engine in Great Britain.

⁴ HAV Bulleid, Master Builders of Steam, Ian Allan, London, 1963, Page 27.

⁵ Bryan Holden & Kenneth H Leech, Portraits of 'Castles', Moorland Publishing, Ashbourne, 1981, ISBN 0 903485 89 3, Page 19.


'N' Gauge is Such Fun!

Many thanks for looking and all best wishes.

Cheerie-B

John

A Coarse Guide to the Steam Locomotive for 'N' Gauge Modellers - Part 76


Hello Chums

More Than Two Cylinders - 4

In the PreviousPart, we considered what was, in my view, the best design for a British four-cylinder locomotive in the 1901-1923 period. Let's consider, briefly, the others:


Great Central Railway

Between 1902 and 1921, Mr JG Robinson designed nine (yes, nine) classes of 4-6-0 for the Great Central. Two of which had four cylinders.

'9P' Class of 1917, later LNER 'B3'

'9Q' Class of 1921 (Mixed Traffic), later LNER 'B7'

Class '9P', the 'Lord Faringdons', were especially impressive-looking engines, but a flawed design. The grate area of 26 sq ft was inadequate the boiler and the 8 inch piston valves had travel of only 4 3/8 inches. These factors combined to make the class heavy on coal - 60-65 lbs per mile according to the Stephenson Locomotive Society.  The LNER converted four to Caprotti valve gear which resulted in a coal saving of around 16%. All six engines in the class remained in service throughout the War, but only one survived into BR days, being withdrawn in April 1949. It's fair to say the 'Lord Faringdons' were something of a disappointment.




[No. 1169, Lord Faringdon, looks thoroughly impressive with a Marylebone to Manchester train in 1921. However, a 'Director' 4-4-0 was equally (or more) capable of handling these trains.]


Mr Robinson's final design of 4-6-0 was probably his best. Essentially, a mixed-traffic development of the 'Lord Faringdons', with 5 ft 8 in coupled wheels, the '9Q' class was designed primarily for working the vacuum-fitted fish trains between Marylebone and Grimsby. They were also at home on excursion trains and suchlike.

The enginemen called these engines 'Colliers' Friends' or 'Black Pigs' due to their appetite for coal. Incidentally, in comparative trials with similar locomotive types, arranged by the LNER, these engines burned less coal. Although I haven't yet tracked down the test results, we need to be aware that this was a comparative figure, not an absolute one. They were still heavy on coal.

Twenty-eight were built in 1921/22, with a further 10 delivered after the Grouping in 1923/24. All survived into nationalisation, with the last example withdrawn in July 1950.
 

Lancashire & Yorkshire Railway

'1506' Class of 1908

'1522' Class of 1920

Following the introduction of Mr Churchward's 'Star' class in 1907, George Hughes introduced his '1506' Class of 4-6-0s for the Lancashire & Yorkshire. There were 20 engines in the class, which was fitted with Joy valve gear and slide valves. These large locomotives, nicknamed 'Dreadnoughts', struggled to match the performance of the excellent L&Y 'Atlantics'. They were also difficult to maintain and someone who was professionally involved with them recalled there was a point when all 20 were under repair at the same time.

ES Cox has written that these engines recorded a coal consumption of 7 lbs per drawbar horsepower hour, the highest he had ever seen. These locomotives averaged 65.2 lbs ¹ of coal per mile. Crikey! It's not possible to give target figures for coal consumption of locomotives in service, but for express passenger work, an engine with superheating, well designed and proportioned valves, and an efficient air/gas/steam circuit should be looking at figures around 35 lbs of coal per mile and about 3 1/2 lbs per drawbar horsepower hour.




['1506' Class 4-6-0 No. 1518 leaves Manchester Victoria with a Southport express. Her impressive appearance is deceptive - the train could be worked as well, probably better, by an 'Atlantic'. And without a doubt, the 4-4-2 would use much less coal.]

Realising something had to be done, Mr Hughes embarked on a drastic rebuilding of the '1506' Class. The revised design had outside Walschaerts valve gear, piston valves and new cylinders. The valve travel was 6 3/8 in. but the lap was moderate at 1 3/16 in. In theory, these ought to have been quite good engines.

"In theory, there is no difference between practice and theory. In practice, there is." Yogi Berra.

Although better than the original engines, coal consumption was still high at 50.2 lbs per mile.

Unbelievably, the LMS built more of the class to help out on former LNWR lines. On these longer runs, their steaming became uncertain and their axleboxes had a worrying tendency to run hot.²




[One of the final series of Mr Hughes' improved four-cylinder 4-6-0s, No. 10467, built for the LMS, leaves Carlisle Citadel with an up West Coast Express. Thankfully, the Lancaster & Carlisle is much easier in the up direction.]


London & North Western Railway

'Claughton' Class of 1911

Dr Tuplin wrote that the '[LNWR 'Claughton'] design was superior to that of the Great Western four-cylinder engines, for example in accessibility of the main mechanism. ...]'³ High praise from someone who was even more of an enthusiast for Mr Churchward's locomotives than I am.

Unfortunately, poor airflow to the grate, inefficient blastpipe design and valves that did not remain steam-tight detracted from the class' performance. Detail design was poor and with a speciality of the trailing coupled axleboxes running hot because, with bearing wear, there was sufficient lateral movement to allow the wheels to shear off the oil pipe feeding the bearing.





[A 'Claughton' in LMS days, No. 5932 Sir Thomas Williams.  Unusually, she is attached to a tender from an ROD Great Central design 2-8-0. Unfortunately, the tender is not included fully in the original photograph - for once it's not the fault of my coarse photography.]


Tinkering with the fitting of Caprotti valve gear, mentioned earlier, and suchlike failed to save the 'Claughtons'. As mentioned previously, two were officially rebuilt as three-cylinder 'Patriots'. After that, the LMS didn't bother with the pretence and the 'Claughtons' faded from the scene. A near miss?


London & South Western Railway

'F13' Class of 1906

'E14' Class (of one) of 1907

'G14' Class of 1908

'P14' Class of 1910 (Mixed Traffic)

'T14' Class of 1911

Oh, no! I've been dreading writing this. I've written earlier about how some High Victorian locomotive engineers struggled in the transition to the Era of the Big Engine. They might have produced 4-4-0s with sparkling performance and 0-6-0s that were still earning revenue in the 1960s. But, when it came to 4-6-0s - whoops-a-daisy!  Probably the most striking example was Dugald Drummond on the LSWR.

Five types of four-cylinder 4-6-0s were introduced from 1906 to 1911. None good and some atrocious. The sole 'E14', No. 335, was nicknamed 'Turkey' by the enginemen due to her appetite for coal. The 'P14' class rejoiced in the nickname of 'Big Gobblers'. Officially, Mr Urie, Mr Drummond's successor, 'rebuilt' the 'G14' and 'P14' as two-cylinder 4-6-0s of class 'H15'. More a face-saving exercise than anything.

The final class, 'T14', 'The Paddleboxes', were the best of the bunch and three survived to be given BR numbers. One was damaged beyond repair by enemy action in 1940.  Mr Drummond's last design for the LSWR was ... a 4-4-0 - the 'D15' Class of 1912. They were excellent locomotives and regarded as 'two coaches better' on the level than the six-coupled locomotives.⁴ It wasn't meant to be like that.





[A rather lovely postcard illustration of LSWR 'Paddlebox' 4-6-0 No. 444 on a Bournemouth express. Based on a photograph and heavily retouched, these colour pictures were hugely popular. Imagine the excitement of a schoolboy receiving this postcard, from a favourite uncle, in the morning post. No. 444 was built at Eastleigh in 1911 and I think the picture is from about that time. Let's hope both our schoolboy and his uncle survived the horrors of 1914-1918. By the way, these illustrations are the sort of thing which provide inspiration for Poppingham - reality enhanced.]


***

That's our overview of the four-cylinder 4-6-0 designs up until the Grouping. In the next part, we'll discuss three other four-cylinder locomotives of the period - two of which were tank engine types. Yes, four-cylinder tank engines.

Post-Grouping, with the glorious exception of the GWR, there were few new four-cylinder designs. None on the LNER,  the 'Lord Nelson' 4-6-0s on the Southern, with the 'Princess Royal' and 'Princess Coronation' 4-6-2s on the LMS. All are impressive engines, but there were never many of them. Also, of course, the LMS 'Garratts' had four cylinders.

It fell to Mr Ivatt the Younger to bring down the curtain on non-GWR four-cylinder engines when his second modified 'Princess Coronation' 4-6-2, No. 46247, City of Salford was released from Crewe Works in 1948. This was the only four-cylinder locomotive, other than former GWR types, to enter service in BR days. And she was a very fine engine indeed.

Of course, Swindon continued to build 'Castles' until No. 7037 left the Works in August 1950. The last of a long line that started almost fifty years earlier with No. 40. Fittingly, they named her Swindon - quite right too. 


¹ ES Cox, Locomotive Panorama, Ian Allan, London, 1965 Page 11.

² ES Cox, Locomotive Panorama, Ian Allan, London, 1965 Page 41.

³ WA Tuplin, British Steam Since 1900, David & Charles, Newton Abbott, 1969, ISBN 0 330 02721 2, Page 89.

⁴ Brian Haresnape and Peter Rowledge, Drummond Locomotives, Ian Allan, London, 1982, ISBN 0 7110 1206 7, Page 91.


'N' Gauge is Such Fun!

Many thanks for looking and all best wishes.

Pip-pip

John

Thank you for yet more Fascinating Facts, John. I don't know how you are managing to keep this mini-series so brief!

Quote from: Train Waiting on March 22, 2025, 03:20:47 PMHaving dealt with the oddities - always such fun

I find the oddities as interesting as anything. Experimentation and occasional mad prototypes are all part of the development process. Some are successful, like the GWR Star class you mentioned (See! I'm learning about the GWR!), and go on to beget successful classes. Others are complete failures and rightly end up back in the furnace. Some in between are unfairly binned before teething troubles are rectified. Duke of Gloucester and the APT spring to mind. Some are built for just one job (the Lickey Banker) and are very successful at it.

Sorry I can't help you with compounding. O S Nock's British Locomotives of the 20th Century, Volume 1 (which I am sure is to be found on your shelves) has quite a few pages on the subject, but his technical writing is too deep for my brain to précis. I wish you luck!

Cheers,

Chris

A Coarse Guide to the Steam Locomotive for 'N' Gauge Modellers - Part 77


Hello Chums

More Than Two Cylinders - 5

I thought it might be worthwhile to include these three four-cylinder types to complete this part of our discussion. Two of them have interesting features to which we might return in a future part.

First, are the LMS 4-6-4T engines. LMS in name only - Mr Hughes was informed of a perceived need for a tank engine for secondary services and decided to base the design on his superheated Lancashire & Yorkshire 4-6-0 'Dreadnought' (we looked at these in Part 75). The original idea was to build 60 (yes sixty), but it then dawned on all concerned how long and heavy (100 tons!) these engines would be, with resulting restrictions on route availability.

In the resulting outbreak of sanity, only 10 4-6-4T locomotives were built, entering service in 1924. Twenty appeared in 1924/25 as 4-6-0s and the remaining 30 were cancelled. The perfect locomotive for these duties appeared after Mr Hughes had retired and Sir Henry Fowler had taken over as Chief Mechanical Engineer - that's not a sentence you expected to read, but the Fowler 2-6-4Ts were excellent engines.





Not unique as British four-cylinder tank engines, but the only class of more than one engine. Not a good investment for the LMS - all were scrapped between 1938 and 1942.

With SuperSpecial thanks to @Papyrus for the trailer in the previous post, next is a much more successful engine - the Midland Railway's one-off 0-10-0 for banking duties on the fearsome Lickey Incline between Bromsgrove and Blackwell. The locomotive was designed and construction authorised in 1914, but work was suspended during the Great War. She emerged from Derby Works on 31 December 1919.





She spent almost her entire working life at Bromsgrove, eventually being withdrawn in May 1956. One of the difficulties encountered with one-off locomotives is that they can spend long periods out of service, waiting for parts to be manufactured or repaired. The LNER's 'U1' 2-8-0+0-8-2, also a one-off banking engine, suffered from this, especially with regard to her boiler. During heavy repairs, the boiler work tends to take longer than the work on the engine - this is why many locomotives received a different boiler, from a 'pool' of spares, during a Heavy General repair.

Alert to this, in 1922 the Midland built a spare boiler for 'Big Bertha' or 'Big Emma', as she was called.  A century later, the splendid people behind the 'A1' 4-6-2 Tornado are following a similar course of action.

Finally, a locomotive which isn't as well known as the Lickey Banker. I have a liking for the smaller companies that found themselves 'Grouped' into the LMS - Highland, Glasgow & South Western, Maryport & Carlisle, Furness and North Staffordshire. It's to the 'Knotty' that we now turn our attention. Its last Locomotive, Carriage & Wagon Superintendent, appointed in 1915, was JA Hookham.

Incidentally, from 8 September 1919, the Deputy Locomotive, Carriage & Wagon Superintendent was a young HG Ivatt - Mr Ivatt the Younger, of whom we have already heard a great deal. He had just returned from serving his country in France, with the rank of captain. Mrs Ivatt also served in France, as a nurse.

Although we do not hear much about him nowadays, Mr Hookham was an innovative engineer - he was a leader in the use of cast iron gland packing rings and provided Sir Nigel Gresley with information about these. In 1922, Mr Hookham's experimental four-cylinder 0-6-0T entered service.





As built, the locomotive, NSR No.23, was intended for passenger work. The North Staffordshire Railway's main routes, put simply, were in the form of a cross - Macclesfield to Colwich (on the LNWR main line), and Crewe to Derby. At its centre was the densely-populated area then known as 'the Potteries' or 'the Six Towns' (did Fenton ever forgive Arnold Bennet for leaving it out of Anna of the Five Towns?), now, in its centenary year, called the City of Stoke-on-Trent.

Rather like the North British in Fife and the North Eastern in County Durham, the 'Knotty' had a monopoly in its area. Lack of competition did not mean a poor service and it was a smartly-run railway.

The area round the Six Towns had a busy local passenger traffic with lots of closely-spaced stations. Mr Hookham's experiment was to see if a four-cylinder locomotive would have such improved acceleration away from the many station stops that it would justify the additional cost and complication. The answer appears to have been in the negative.

Although she was rebuilt as a tender locomotive for freight work in 1924, she has the distinction of being the first four-cylinder tank engine in Great Britain. Numbered No.2367 by the LMS and renumbered 8689 in 1928, she was withdrawn in the same year.


***

Having now completed a historical overview (rather longer than I anticipated) of locomotives with more than two cylinders, the next part will be more mechanically-minded as we discuss why have more than two cylinders, including the advantages and disadvantages.


'N' Gauge is Such Fun!

Many thanks for looking and all best wishes.

Toodle-pip

John

A Coarse Guide to the Steam Locomotive for 'N' Gauge Modellers - Part 78


Hello Chums

More Than Two Cylinders - 6

We've had an overview of the history of locomotives with more than two cylinders, commencing in 1846 with the three cylinder locomotive built by Robert Stephenson & Co. With the exception of compound locomotives, which will have a part of this astonishingly brief mini-series to themselves, and some one-off examples, it wasn't until the commencement of the Era of the Big Engine that much interest was shown in more than two cylinders.

Before we proceed, let's pause for a second to review some of the High Victorian 4-4-0s attributed to one locomotive engineer. After having been unkind to him regarding his 4-6-0s, I decided to choose Dugald Drummond:

NBR '476' Class - the 'Abbotsfords' - boiler pressure 150 psi. 18" x 26" cyls.

Caledonian '66' Class - boiler pressure 150 psi. 18" x 26" cyls.

LSWR 'T9' Class - the 'Greyhounds' - boiler pressure 175 psi. 18 1/2" x 26" cyls.

LSWR 'D15' Class - boiler pressure 200 psi. 19 1/2" x 26" cyls.

A process of gradual development of the same basic design. How long did this take:

The years of introduction of the classes listed were:- 1876, 1884, 1899 and 1912.

Thirty-six years! The main differences were the larger boiler diameter on the later engines. Mr Drummond was ahead of many of his contemporaries in the use of a boiler pressure of 200 psi.





I believe the typical British inside-cylinder 4-4-0 of this period represented something of an engineering ideal. But, when the time came, from, say 1902, to move beyond it, some locomotive engineers, to put it bluntly, weren't up to the job.

**

As we have seen, some attempts at more than two cylinders in, roughly, the 1902-1922 period produced real rotters. It appears that locomotive engineers who were able to produce truly excellent 4-4-0s and 0-6-0s, in the High Victorian style, hit serious trouble when they attempted to design a Big Engine. Others rose to the challenge - David Jones (successful 4-6-0s), Vincent (later, Sir Vincent) Raven (three cylinders) and George Jackson Churchward (excellent boilers, long lap/travel valves, superheating, four cylinders...). The list goes on and on in the case of Mr Churchward. In my view, as a British locomotive engineer, he was second only to Robert Stephenson.

Notwithstanding far too many embarrassing and sometimes almost comical failures (remember the Caledonian three-cylinder 4-6-0 and Dugald Drummond's various 4-6-0s on the LSWR?), it was possible to build good Big Engines. As we've seen, in so doing, locomotive engineers soon found themselves considering the use of more than two cylinders. Let's now attempt to discuss why. 


Cylinder Volume

We've discussed this in some detail earlier. A combination of standard gauge track, British loading gauge constraints (our high station platforms!) and fears about excessive piston speeds limited cylinder size.

In order not to compromise axlebox size, 20 in. diameter was about the maximum desirable for inside cylinders. We have seen already how locomotives with inside cylinders of a larger diameter tended to have bearing problems.

Although the different pre-Grouping companies had their own loading gauge limitations (much of the GWR being especially generous), 21 in. diameter was about the maximum permissible for outside cylinders before our engines started demolishing station platforms. We've already seen how the 'Horwich Moguls' had their 21 in. diameter cylinders inclined steeply due to tight platform clearances on parts of the LMS system.

Although Mr Churchward happily used a piston stroke of 30 in., which was carried on until the end of construction of GWR large locomotives with two cylinders, other designers did not go beyond a 28 in. stroke.

These constraints of track gauge, loading gauge and piston speed combined to set the maximum cylinder dimensions and, hence, volume.

In order to get more power, there were two possibilities - increase the cylinder volume by having an additional cylinder or cylinders, or increase the boiler pressure. We have already discussed how many locomotive engineers ignored Mr Churchward's lessons and stuck to lower boiler pressures. The LMS 2-6-0, mentioned ante, had a boiler pressure of only 180 psi. Mr Hughes had a serious aversion to higher pressures.


Lower Boiler Pressure

Perceived by some as an advantage. We have already noticed many locomotive engineers were wary of the maintenance costs associated with higher boiler pressures, even although Mr Churchward had shown that wasn't necessarily the case. The higher cylinder volume obtained with three or four cylinders allowed the same nominal tractive effort to be obtained with lower boiler pressures. This led to a temptation to reduce boiler pressures. As we have seen, something similar happened with superheating. Mr Hughes' first 'Deadnought' class, at whose appetite for coal we have already marvelled, had a boiler pressure of 180 psi. A GWR 'Star' was pressed to 225psi.

It's not as if Mr Churchward's lessons were a state secret. They could be learnt by reading the published information and standing at the end of a station platform. And, of course, he spoke at the relevant Technical Institutions. But it took over a decade before others (hats off to Mr Maunsell and his chaps) really began to apply them.

Of course, the corollary of this is, if a locomotive engineer was able to countenance higher boiler pressures, the desired nominal tractive effort could be achieved with a reduced cylinder volume. The Stanier 2-6-0s of 1933 had 18" x 26" cylinders, rather than the 21" x 26" of the 'Horwich Moguls' of 1926. This was allowed by the use of the 'Churchwardian'  boiler pressure of 225 psi in the later engines.

Similarly, the BR Standard 'Britannia' 4-6-2 and '9F' 2-10-0 locomotives had two 20" x 28" cylinders. The boiler pressure in each case was 250 psi which, as we discussed earlier, emerged as the highest practicable working pressure in Great Britain.


'Nosing'

Much more of a problem with two big outside cylinders. The locomotive sort of sways from side to side with the piston stroke, leading to rough riding and an uncomfortable fore-and-aft movement being transmitted to the train.

The GWR 'County' 4-4-0s of 1904 had a particular reputation for this misbehaviour. I maintain it wasn't Mr Churchward's fault. The LNWR was to blame with its weight restrictions on the Shrewsbury & Hereford joint line. I believe Mr Churchward, who designed the class with the restrictions of this railway in mind, always considered the 'Counties' as a stop gap. Once heavier locomotives were permitted, they could be dismantled and their standard parts used for new construction. Certainly, they were rough riders; with 18" x 30" outside cylinders and a coupled wheelbase of only 8 ft 6 in, it would be difficult to imagine they would be anything else.





There is a 'back and forward' motion originating from the reciprocating masses of the locomotive's pistons, piston rods, crossheads and a proportion of the connecting rods. As we saw with the GWR 'County' 4-4-0s, there is also a phenomenon called 'swaying couple' caused by the action of the reciprocating parts which is the cause of 'nosing' mentioned above. Both of these, if allowed to develop unchecked could lead to the locomotive becoming potentially so unbalanced that it throws itself off the track.


Hammer-Blow

Let's simply say this is a measure of how much a steam locomotive 'pounds' the track and under-line structures as it runs along.

Two-cylinder engines, with the cranks at 90^o are, by their nature, unbalanced. Much attention was paid by locomotive engineers to efforts to balance the reciprocating weight. Three and four-cylinder engines are inherently better balanced.

Efforts to allow for smoother riding by adding balance weights to the coupled wheels can provide a partial solution. But, you know how solutions can bring their own problems? Higher amounts of balance increase hammer-blow. And hammer-blow is related to rotational speed. Unfortunately, the hammer-blow increases as the square of the rotational speed. Bother!

Locomotives with four or, especially, three cylinders are naturally better balanced than those with two cylinders. Unless egregiously inept design gets in the way, much lesser hammer-blow than for a two-cylinder locomotive of equal power was obtained automatically by increasing the number of cylinders.

I'm conscious of my amount of over-simplification, but some actual examples might be helpful. It was normal to calculate hammer-blow at five revolutions of the driving wheels per second (rps). I have seen 8rps, used but this can give misleading figures for hammer-blow due to the speeds involved (97mph for an LNER 'K3' for example).

The GWR provides an interesting case study as the two-cylinder 'Saint' and four-cylinder 'Star' are pretty much the same 4-6-0 engine, differing in the number of cylinders:

The 'Star' has a hammer-blow of 2 tons at 5rps, 72mph.

For the 'Saint', the hammer-blow is 4.8 tons at 5rps, 72mph.

Hammer-blow is a consequence of the percentage of the reciprocating weight which the designer chose to balance. For two-cylinder engines, the percentage in British practice ranged from 40% to 85% (the GWR '6100' 2-6-2T), with about 50% being typical.

The better inherent balance of locomotives with three or four cylinders meant that higher balance percentages of reciprocating weight can be used and the hammer-blow will still be a low figure:

An LMS '5XP' 'Jubilee' 4-6-0, with three cylinders, has a balance percentage of 66.6% with a hammer-blow of 0.61 tons at 5rps, 72mph.

A Southern 'Schools' 4-4-0, again with three cylinders, has a balance percentage of 30% with a hammer-blow of 0.27 tons at 5rps, 70mph.




[SR 'V' or 'Schools' 4-4-0 No. E901 Winchester. Was there a better class of 4-4-0 in Great Britain? Ten-foot coupled wheelbase and three 16 1/2" x 26" cylinders. Like the GWR 'County', the class was designed for a railway with weight restrictions (the Hastings line). The use of three cylinders (and a slightly longer coupled wheelbase) made the riding so much better than the GWR engine. The engine weighed 67 tons 2 cwt but had little hammer-blow.]


Such a reduction in hammer-blow, with consequentially less potential for damaging the track and under-line structures, is an important advantage of more than two cylinders. A good civil engineer will consider hammer-blow when calculating the maximum permissible axle weights for any route. If the civil engineer chooses to be co-operative, a locomotive with low hammer-blow can be allowed a higher axle weight. As we have seen, the LNWR 'Claughton' four-cylinder 4-6-0s had a smaller than optimal diameter boiler due to the civil engineer deciding to be uncivil.

This possible allowable additional weight was helpful, as a a locomotive with more than two cylinders will weigh more than a similar two-cylinder engine:

GWR 'Saint two-cylinder 4-6-0 - 72 tons.

GWR 'Star' four-cylinder 4-6-0 - 75 tons 12 cwt.

A less exact comparison, but one which doesn't involve GWR locomotives:

LMS '5MT' 'Black Five' two-cylinder 4-6-0 - 72 tons 2 cwt.

LMS '5XP' 'Jubilee' three-cylinder 4-6-0 - 79 tons 11 cwt.

**

Towards the end of the steam era, one locomotive engineer decided to take more advantage of the inherently better balance of a locomotive with more than two cylinders.

Imagine a 4-6-2 with nil tons hammer blow at 5rps, 66mph. For 8rps, 106mph, the hammer-blow was still nil tons. How on earth was this achieved?

By taking advantage of the natural balance of a three-cylinder engine and deciding that the length of a 'Pacific' meant that 'swaying couple' could be ignored, the designers used a reciprocating weight balance percentage of 0%.

The engineer was OVS Bulleid and the locomotive was the 'Merchant Navy' class 4-6-2.




**

A few years later, a different team of engineers were designing a 4-6-2. They decided on two cylinders. Percentage balancing of the reciprocating weight from 60% to 30% were considered and 40% was decided on. Hammer-blow was 6.6 tons. The locomotive class concerned is, of course, the BR Standard 'Britannia'.

I haven't quite got to the end of the advantages of more than two cylinders, but I feel this postington has gone on long enough. The next part will endeavour to carry on from where we left off.


'N' Gauge is Such Fun!

Many thanks for looking and all best wishes.

Cheerie-bye

John

A Coarse Guide to the Steam Locomotive for 'N' Gauge Modellers - Part 79


Hello Chums

More Than Two Cylinders - 7

Let's carry on with the advantages of more than two cylinders.

Better Starting

FAS Brown quoted Sir Vincent Raven, speaking in 1925, about his use of three cylinders:

'It was on account of the even starting effort given by the 120 degree cranks with a three-cylindered engine that I was led to use it.'

Mr Brown continued in parenthesis:

'The effect appears to be much the same as would be experienced by the mythical three-legged Manxman astride a three-cranked bicycle.'¹

This was not lost on Mr (later, Sir Nigel) Gresley who had been Chief Mechanical Engineer of the LNER since 1923. Prior to that, he held the equivalent post on the Great Northern. Mr Brown quotes from a summary of the advantages of three-cylinder proulsion which was given by the, then, Mr Gresley in a paper read before the Institution of Mechanical Engineers at Newcastle in 1925. This was, I understand, the same occasion at which Sir Vincent spoke, as quoted above.

Here is the 'Gresley List':

1) Less coal consumption than with a two-cylinder type of equal power.

2) Increased mileage between general repairs.

3) Less tyre wear than with the two-cylinder type.

4) An earlier cut-off in full gear.

5) Lower permissible factor of adhesion; thus with a given weight on the coupled wheels a higher tractive effort can be obtained without increasing the tendency to slip.

6) Lighter reciprocating parts can be used, consequently hammer-blow on the track is reduced; and for equal bridge stresses a greater permissible weight can be allowed on the coupled wheels of the three-cylinder type.

Many of these relate to what we have already discussed and apply also to four-cylinder engines. We noted the GWR two-cylinder 4-6-0 'Saint' class running 80,000 between heavy repairs compared with the four-cylinder 'Star' class managing 120,000 miles.

Here is the last point in the list (as arranged by me!):

7) More uniform starting effort than with either two cylinders or four cylinders with directly opposed cranks.

This demonstrates that Sir Nigel Gresley, as, for convenience I shall refer to him from now, was thinking along the same lines as Sir Vincent Raven.  Indeed, the North Eastern had many three-cylinder locomotives in service before Sir Nigel built his first (2-8-0 No.461 in May 1918), it is fair to suggest Sir Nigel had been persuaded to try three-cylinder locomotives by their successes on the neighbouring railway.

Thanks to the courtesy of Mr Churchward, Sir Nigel was able to borrow the GWR dynamometer car for comparative tests between No. 461 and an earlier Gresley 2-8-0, No. 456, which had two cylinders.  The dynamometer car charts showed noticeably smoother starts by No. 461. The charts also showed No. 461 had a more even pull with a loaded coal train up the 1 in 200 bank between Hitchin and Stevenage. 




[Unfortunately, I don't appear to have a photograph of No. 461.  The picturingham shows No. 477, a production version, of Class 'O2',  which differed from the prototype in some respects which we might discuss later. A photograph of No. 461 would be most welcome.]


If Sir Nigel had been persuaded, he was now convinced. Allegedly, after the trials, he expressed the intention of designing and building only three-cylinder locomotives in future. This didn't quite work in practice, as we can see by the LNER 'J38', 'J39' and 'N2' classes, but he followed the principle for larger locomotives.


Four Cylinder Innovation

The benefit of smoother starting obtained by the 120^o degree cranks of a three-cylinder engine was not lost on certain locomotive engineers who were more inclined towards the use of four cylinders. The usual arrangement for a four-cylinder locomotive is to set the cranks at right angles, which gives four exhaust beats for each revolution of the driving wheels.

That's why a four-cylinder engine sounds like one with two cylinders. Three-cylinder locomotives have six exhaust beats for each revolution of the driving wheels. The six beats cause a smaller variation on the draught on the fire and, as Sir Vincent and Sir Nigel observed, the difference between the maximum 'pull' and the mean 'pull' is reduced. ²

In 1920, Harold Holcroft, of Mr Maunsell's staff on the SE&CR, read a paper, Four-Cylinder Locomotives before the Institution of Locomotive Engineers. In the paper he pointed out a number of advantages which would arise from the adoption of a crank setting of 135^o between inside and outside cylinders in place of the conventional 180^o setting.

We have met Mr Holcroft before and we'll meet him again soon. The setting of the cranks he proposed gives eight exhaust beats for each revolution of the driving wheels of a four-cylinder engine and Mr Holcroft suggested this would reduce stress on axleboxes and motion parts.

One result of this was the appearance, in 1922, of Mr Hookham's experimental superheated 0-6-0T locomotive for the North Staffordshire Railway. This unique locomotive, NSR No. 23, has come to our prior attention as Great Britain's first four-cylinder tank engine. We noted she was intended to test if the stopping passenger trains serving The Potteries could be speeded up by better acceleration away from the many station stops.

This little locomotive can claim another first. As part of Mr Hookham's experiment, she was built in such a way that she had eight exhaust beats for each revolution of the driving wheels. If a three-cylinder locomotive with six beats gives smoother starts, would a four-cylinder engine with eight beats be even better?

Although I haven't been able to find any official account of the trials, the opinion expressed in the written sources I have found is the experiment was not a success. The nearest to a contemporary source I have found is from 1927.³

We discussed earlier that the LMS rebuilt her as an 0-6-0 for goods work in 1924 and she was cut up in 1928.  For your interest, I have managed to include a picturingham of her in her rebuilt state, as LMS No. 2367. They renumbered her as No. 8689 just before she was withdrawn.





I hope you enjoyed reading about Mr Hookham's 'Double First' tank engine. Her history doesn't appear to be that well-known. The next locomotive type featuring eight exhaust beats for each revolution of the driving wheels is much more familier.


Mr Maunsell's 'Lord Nelsons'

Although the original Urie engines required some improvement, Mr Maunsell's own version of the 'N15' 'King Arthur' 4-6-0, introduced in 1925, was a very good engine indeed. However, The Southern Railway's Operating Department planned to run 500-ton trains (equivalent to about 15 carriages of Southern stock) at 55mph average speed.⁴ and appears to have projected there would be a requirement for 16 locomotives capable of working these trains by 1928.

Mr Maunsell and his assistants, James Clayton and Harold Holcroft, got to work to design such a locomotive which would comply with George Ellson's limit of axle-loading of 21 tons. They knew not to fall out with the Chief Civil Engineer. The 'King Arthurs' were already over 20 tons axle-loading, so there was not much room for manoeuvre.

To decide whether the new engine was to be a 4-6-2 or 4-6-0, Mr Maunsell made use of his good relations with Sir Nigel Gresley on the LNER and Charles Collett on the Great Western to arrange for Mr Clayton to travel on the footplates of 'A1' 4-6-2 and  'Castle' 4-6-0s respectively. Mr Clayton was highly impressed by the 'Castle' and considered the relatively short distances to be run on the Southern did not require a wide firebox.

Mindful that a 4-6-0 would be cheaper to build and that the 'Castle' had made such a good impression, Mr Maunsell decided on a 4-6-0. The next decision was three or four cylinders. The former SECR 2-6-0, No. 822, which they had designed, had shown the advantages of three cylinders with six beats for each revolution of the driving wheels.

However, Mr Clayton's high opinion of the 'Castle' led them to favour four cylinders, although the GWR practice, with normal 90^o crank setting, gave four beats for each revolution of the driving wheels. Mr Maunsell decided to experiment with Mr Holcroft's crank setting arrangement and a Drummond 'P14' 4-6-0, No. 449, which had been superheated by Mr Urie, was converted to eight beats for each revolution of the driving wheels in early 1924.

Tests were conducted with the engine in its original condition and then with the 135^o crank setting. The converted locomotive used 10% less coal per ton-mile and evaporated more water per pound of coal. The driver stated he could start heavy trains in a way he couldn't with the unconverted locomotive because the eight light exhaust beats for each revolution of the driving wheels didn't pull the fire about in the engine's shallow firebox in the way four strong ones would have done. The Test Engineer reported in favour of the change and Mr Maunsell agreed that the 135^o crank setting should be adopted on the new locomotive.⁶ 

No. E850 Lord Nelson left Eastleigh Works in August 1926 and was subjected to extensive test, in which she performed without difficulty. Satisfied with this, Mr Maunsell obtained authority to build the remaining 15 members of the class which entered service in 1928/29.





The 'Lord Nelson' class were reliable engines, free from mechanical troubles, but, as is well known, their performance in service was variable. Their steaming never appeared to be as free as the excellent 'King Arthur' class.⁷ There have been several theories put forward over the years to explain this. My own is the draughting wasn't quite right. We might return to this later.

Five of the class received major modifications in Mr Maunsell's time. The one which concerns us now is No. 865 Sir John Hawkins. It is, I think, an interesting story.

During a meeting of representatives of the Running Departments of the 'Big Four', the Great Western men tried to convince those from the Southern that, contrary to the opinion of Sir Vincent Raven and Sir Nigel Gresley, a train was more rapidly accelerated by a series of 'tugs' than by the smoother tractive effort of the 'Lord Nelson' engines' eight exhaust beats for every revolution of the driving wheels. The Southern's Running Superintendent suggested this to Mr Maunsell, who said he was willing to put it to the test if an opportunity presented itself.

This occurred in 1934 when No. 865 required repairs to the crank axle. During the repairs it was altered to a 180^o setting, rather than the 135^o standard for the class. As such, the engine now had the normal four-cylinder arrangement of four exhaust beats for every revolution of the driving wheels.

The results are reported slightly differently.

Dr Tuplin, in his usual forthright style, stated: 'The eight-beat principle [...] showed no advantage whatever over four beats.'⁸

OS Nock was, on the contrary, supportive of the eight-beat arrangement: 'Negative [test] results [...] served to confirm his [Mr Maunsell's] faith in the original design.' He went on to state, 'None of the experimental modifications of 'Lord Nelson'  class engines showed any particular advantage over the standard design.⁹

SC Townroe's comments are interesting: 'After a long period it was clear that there was no difference. Some drivers declared in favour of No. 865, others opined that the 'bark' had improved, but not the 'bite'.'¹⁰

We are fortunate that Mr Holcroft mentioned, briefly, the matter in his memoirs: 'In normal service the alteration had no marked effect on acceleration, but when the engine was worked hard in rough weather or with heavy load the coal supply on the tender was quickly reduced. No tests of coal consumption were made with No. 865, but Nine Elms Shed recorded that it averaged 7 per cent. more than other engines of the class.'¹¹

None of the sources available to me mention whether any adjustment was made to the draughting of No. 865 at the time of the conversion.

What became of the eight beats idea?

The Southern built no more four-cylinder engines and the success of the subsequent three-cylinder 'Schools' class had Mr Maunsell's team looking in that direction should another design be required. Later, Mr Bulleid preferred three cylinders.
 
We can ignore the LNER as it stuck to three-cylinders for the larger engines. After Sir Nigel Gresley's death, Edward Thompson instigated a policy of two cylinders for all but the largest.

Signor Caprotti wrote to Mr Holcroft to say that he had read his paper and converted a four-cylinder locomotive, fitted with his poppet valve gear, to the eight-beat setting. In 1926, when the LMS was fitting some 'Claughton' 4-6-0s with Caprotti valve gear, these used the eight-beat principle. And that was that. Sir William Stanier stuck to the conventional crank setting he knew so well from his time on the Great Western.

**

Now that we have discussed the advantages of more than two cylinders, we shall, in the next part, turn our attention to the disadvantages. Then, after that, we had better get on to compounding. Help!

Lots 'N' lots of lovely footnotes this time.


¹ FAS Brown, Nigel Gresley Locomotive Engineer, Ian Allan, London, 1961, 1975 edition, ISBN 07110 0591 5, Page 40.

² WA Tuplin, British Steam Since 1900, David & Charles, Newton Abbot, 1969, ISBN 0 330 02721 2, Page 81. Dr Tuplin suggests the difference between the maximum 'pull' and the mean 'pull' is 10% for two cylinders and 5% for three cylinder.

³ EL Ahrons, The British Steam Railway Locomotive 1825-1925, Locomotive Publishing Company, London, 1927, Page 364.

⁴ SC Townroe, The Arthurs, Nelsons and Schools of the Southern, Ian Allan, London, 1973, ISBN 0 7110 0434X, Page 48. Mr Townroe reminds us that only one platform at Waterloo could accommodate a train of that length. Trains comprised of Pullman or Wagon-Lits stock were heavier than those formed with standard Southern stock.

⁵ Harold Holcroft, Locomotive Adventure Vol. 1, Ian Allan, London, Undated (around 1960?), Page 119. Mr Holcroft mistakenly states it was a shunting tank engine.

⁶ Holcroft, Page 120.

⁷ OS Nock, Southern Steam, David & Charles, Newton Abbot, 1966, ISBN 0 330 02681X, Page 93.

⁸ Tuplin, Page 81.

⁹ Nock, Page 95.

¹⁰ Townroe, Page 47.


'N' Gauge is Such Fun!

Many thanks for looking and all best wishes.

Toodle-pip

John

Now I have just been surprised by another part of this ultra-brief series while I was writing my post ...
But as the smooth running of multi-cylinder engines is clearly an advantage it still fits here before the disadvantages will be discussed in the next part.

Quote from: Train Waiting on March 22, 2025, 03:20:47 PMFinally, an eight-cylinder locomotive - yes, you read that correctly - the Paget 2-6-2. Cecil Pager was was Works Manager of the Midland Railway's Derby Works. Officially, the project was his own private one, but the locomotive was built at Derby and the Midland ended up contributing £2,000 in order that it could be completed. The locomotive emerged from Derby Works in February 1909, as Midland No. 2299. It ran tests, but never entered service. The project was abandoned by 1913.

Very interesting, I have never heard of this locomotive with a "flat-eight" engine before.

If you wanted a steam loco with V-eight power then there was one in Germany: the 19 1001 (Henschel's 25,000th locomotive), completed during the Second World War in 1941


works photo Henschel, from Eisenbahnstiftung

This was a 2-8-2 (or – as the driving axles were not coupled – a 2-2-2-2-2-2?) where four V-twin steam motors powered the four driving axles. The drivers were unusually small (1,250 mm) for such a high-speed locomotive certified for 175 km/h – just over half the size of the comparable classes 05 and 61 (2,300 mm) – but the 19 1001 was exceptionally smooth even at top speed.

The steam-motor locomotive was one of the more promising and successful experiments of the late steam locomotive era. The 19 1001 was even shipped to the United States after the war for technical examination but steam didn't have a future there, and she was scrapped in the early 1950s.

A Coarse Guide to the Steam Locomotive for 'N' Gauge Modellers - Part 80


Hello Chums

More Than Two Cylinders - 8

We've discussed the advantages of more than two cylinders. Time, now, to consider the disadvantages. In steam locomotive engineering there is never something for nothing. It's always a balance between advantages and disadvantages.

The main disadvantage of a locomotive with more than two cylinders is that it has more than two cylinders. Very early on, it was established that two cylinders are the minimum if we want our engine to be able to start. The traction engine chaps can manage with a single cylinder because they can give the flywheel a bit of encouragement if the engine doesn't start when the regulator is opened.

Our locomotive engineer is stuck with a minimum of two cylinders but has chosen to have three or four. We'll ignore articulated engines and oddities, various.

Our locomotive engineer, having made that choice means we can have a list of disadvantages:

More weight;
More moving parts;
More friction;
More maintenance;
More lubrication.

These can be summarised simply as more cost.

And, assuming our alternative two cylinders are outside:

A crank axle is required.


The moving parts associated with the inside cylinder require cleaning, inspection, lubrication and maintenance - all of which involve greater or lesser physical contortions from our enginemen, shed fitters and engine cleaners. This all takes time and, even at the poor rates of pay in steam days, money. And, if corners are cut, the chance of failure on the road is greatly increased.

Let's assume our locomotive engineer is willing to countenance the disadvantages and the company will bear the costs (after all it will be Driver A Rotundity, a year from retirement, who has got to oil thoroughly that inside big-end at 0404 on a January morning. Such fun!).

Two cylinder engines have two separate sets of valve gear. Located inside or outside according to our locomotive engineer's preference. But what about that additional cylinder or cylinders?


Four Cylinders

It's actually rather easy if we are thinking about designing a four-cylinder engine. Right from Mr Manson's 4-4-0 No. 11 of 1897 for the G&SWR, locomotive engineers were glad to take advantage of the fact that a four-cylinder locomotive can manage happily with only two sets of valve gear, provided it is equipped with rocker shafts or similar to work the valve on another cylinder. The crank settings on a four-cylinder engine allow for this.

Just think of all those GWR four-cylinder 4-6-0s, built from the Edwardian age until the 1950s, with two sets of inside Walschaerts valve gear. I've exaggerated slightly for effect - I concede happily that 1950 was the last year of the 1940s.

But, Swindon, why not put the valve gear outside?

You know what happened when, after what I hope was an agreeable luncheon at the Athenaeum, Mr (later, Sir William) Stanier agreed to forsake the GWR for the LMS. Of course, Mr Stanier insisted the Chairman of the Great Western gave his approval. Sir James Milne approved graciously and New Year's Day 1932 was the day that changed locomotive matters on the LMS. Its Scottish Directors, Officers and Servants caught up on 2 January.

Mr Stanier set about designing a mighty 4-6-2 for the LMS. This was the four-cylinder 'Princess Royal' class and they looked a bit like an elongated GWR 'King' with a wide firebox. Did Mr Stanier take advantage of his distance from Swindon to do away with the inside Walschaerts valve gear?





No. He went two better and fitted these engines with four independent sets of Walschaerts valve gear - two outside and two inside. Lots 'N' lots of lovely oiling points for the driver. No. 6205, Princess Victoria was converted, in 1938, so that the outside valve gear operated the valves for the inside cylinders by means of rocking levers - a reversal of GWR practice. You can easily identify this engine in pictures as she has a large 'Y'-shaped motion bracket on each side. 

When it came to the next LMS 'Pacific', many changes were made - the GWR 'swept-back' cylinders, going back to the time of the de Glehn 'Atlantics', were replaced with in-line cylinders, the layout of which was inspired by the distinctly uninspiring L&Y 4-6-0s that we have encountered already. And two outside sets of valve gear were deemed sufficient.

Mr Stanier was on a Government assignment in India when the detailed design of the 'Princess Coronation' class was underway. A brilliant chap called Tom Coleman, the Chief Draughtsman, was in charge. Didn't he do well? By the way, years earlier, Mr Coleman had been on the 'Knotty' with Mr Ivatt the Younger. 'Tis interesting how some names keep appearing in this astonishingly brief mini-series.


Three Cylinders

Unlike the four-cylinder engine with cranks at 'square' angles, a three-cylinder locomotive is a different kettle of degrees. We have discussed the advantages of three-cylinder engines with their cranks set at 120^o, but they have a disadvantage - it's no easy matter to operate the valves for one cylinder from the valve gear from another.

Sir Vincent Raven on the NER, and Sir Henry Fowler (as much as he had any influence over the matter) and Sir William Stanier on the LMS took the path of least resistance - a separate set of valve gear for the inside cylinder. Edward Thompson and Arthur Peppercorn, in the last years of the LNER did the same thing.

Nice 'N' easy. Now for the complication...

In 1884, David Joy, whom we met earlier, designed and patented a form of 'conjugated' motion for three-cylinder marine engines in which the valve of one cylinder was actuated by the combined motion of the valve gears operating the valves of the other two cylinders.

Forward now, 24 years, and a young Harold Holcroft is a draughtsman in Swindon Works. Together with his friend, RG Hannington, who later became Locomotive Works Manager, he was spending his spare time in the winter evenings scheming out a three-cylinder passenger engine. The valve gear for the middle cylinder worries them, as an inside valve gear would be offset from the centre line of the locomotive which would not be acceptable in Swindon practice.

Mr Hannington was soon promoted, leaving Mr Holcroft to continue thinking about the problem regarding inside valve gear. He believed there must be a solution analogous to the use of rocking levers in a four-cylinder engine. In early 1909 he arrived at a solution using [I've simplified this] two rocking levers with their arms in a 1 to 2 ratio.

He made a model and took it into the Drawing Office. Mr Churchward was intrigued by the model and discussed it at length with Mr Holcroft and the senior draughtsmen, going so far as telling Mr Burrows, the Chief Draughtsman, to apply for a patent. Mr Churchward considered he was too committed to four-cylinder propulsion to build a three-cylinder engine.

Mr Churchward was a kindly man and, as he departed, he turned to Mr Holcroft and said, "Now, young man, what you should do next is to make one valve gear serve for the two valves in a two-cylinder engine - and your fortune's made.'¹

In March 1914, Mr Holcroft was appointed as Leading Locomotive Draughtsman at Ashford Works on the SE&CR. His association with Mr Maunsell had begun. Although relatively junior, he requested an interview with Mr Churchward before departing Swindon. Typical of Mr Churchward's kindly manner, this was granted. Mr Churchward took a keen interest in Mr Holcroft's new appointment and, as he was leaving, said, "Now remember this; wherever you may go or whatever you may do, always stick up for the Great Western."²

**

Mr Holcroft, with his ideas for a 'conjugated' valve gear for three-cylinder locomotives, was now on the SE&CR and, later, the Southern. Did the Southern end up with lots 'N' lots of lovely three-cylinder engines? With conjugated valve gear?

Yes and no. Mr Maunsell got Mr Holcroft to design three-cylinder versions of his 'N' 2-6-0 and 'K' 2-6-4T. These engines appeared in 1922 and 1925 respectively.




['N1' three-cylinder 2-6-0, No. 822. Completed at the end of December 1922, this was the last engine to be built for the SE&CR.]




['K1' three-cylinder 2-6-4T No. A890. Withdrawn with all the two-cylinder 'K' or 'River' class locomotives after the fatal Sevenoaks derailment on 24 August 1927, she was rebuilt as a 'U1' 2-6-0 in June 1928.]


Mr Maunsell had been impressed by the better acceleration and smoother running of Nos. 822 and A890. However, he was concerned about the over-running of their inside valves due to wear in the various joints of the conjugated valve gear.

A batch of five 'N1' 2-6-0s were built in 1930 and these had three separate sets of Walschaerts valve gear. Likewise, the 20 'U1' 2-6-0s, built in 1931. Nos. 822, now A822, and A890 were converted subsequently to three sets of valve gear. Other Maunsell three-cylinder classes such as the 'Z' 0-8-0T, 'W' 2-6-4T and 'V' or 'Schools' 4-4-0 had separate valve gear.




[I like to think this SuperSpiffing picturingham of 'Schools' 4-4-0 No. E900 Eton could be from Poppingham. The locomotive's valve gear is reminiscent of Hornby gauge '0' tinplate. Such fun!]


Did these developments mean three separate sets of valve gear became established as the universal approach for three-cylinder locomotives in Great Britain?

No. We'll discuss briefly in the next part and then it's on to compounding.


¹ Harold Holcroft, Locomotive Adventure Vol. 1, Ian Allan, London, Undated (around 1960?), Page 67.

² Holcroft, Page 76. 


'N' Gauge is Such Fun!

Many thanks for looking and all best wishes.

Cheerie-bye

John



 

Going off on a complete non-sensical tangent here, another advantage of the 3-cylinder locomotive is that you can dance to it!

A few years ago, Flying Scotsman visited the Bluebell Railway, so we naturally booked a trip. As it accelerated out of the station, Mrs Papyrus, who is a musician of the Irish persuasion, asked "Why does it chuff in jig time?" "Three cylinders, O best beloved," I replied. And it's true - it beats to the unmistakeable 'diddley, diddley, diddley, diddley' of an Irish jig. Strangely, there is no such distinctive rhythm to two and four cylinder engines. You feel you ought to be able to dance a reel but you can't. Very curious.

Sorry for that diversion into frivolity. I'll get back in my box. More fascinating facts, please John!

Cheers,

Chris

Quote from: Papyrus on March 31, 2025, 05:33:21 PMGoing off on a complete non-sensical tangent here, another advantage of the 3-cylinder locomotive is that you can dance to it!

A few years ago, Flying Scotsman visited the Bluebell Railway, so we naturally booked a trip. As it accelerated out of the station, Mrs Papyrus, who is a musician of the Irish persuasion, asked "Why does it chuff in jig time?" "Three cylinders, O best beloved," I replied. And it's true - it beats to the unmistakeable 'diddley, diddley, diddley, diddley' of an Irish jig. Strangely, there is no such distinctive rhythm to two and four cylinder engines. You feel you ought to be able to dance a reel but you can't. Very curious.

Sorry for that diversion into frivolity. I'll get back in my box. More fascinating facts, please John!

Cheers,

Chris

Well, one of Gresley's designs was known as a 'Tango'!

Martyn

Just remembered a couple more.

The K1's were Ragtimers, the K3 Jazzers, and it was the O1s that were Tangos.

 And of course, the Liverpool St Jazz service....

However, we're a bit off topic as only the K3 had three cylinders, the other two classes only had two.

Plenty of dance style there, Chris.

Martyn

In three-phase electrical power distribution the phases are at 120° offsets and the current in the common return conductor is zero, which is why it can be omitted. Hence a three-phase railway such as the Jungfraubahn has two overhead wires for two of the phases and the running rails carry the third.

(An exercise for the reader is to show why the return conductor current is zero, using the formula sin(A + B) = sin A cos B + cos A sin B.)

The reciprocating motion of a steam engine piston is roughly sinusoidal, so its velocity (the first derivative) is also roughly sinusoidal, as is its acceleration (the second derivative). As you know, F = ma, so the force needed to accelerate the mass of the piston back and forth is also roughly sinusoidal.

Three sinusoidal forces at 120° offsets sum to zero, so a three cylinder engine with 120° cranks has at least some of its forces in balance, which will contribute to smooth running at high speeds.

(Laverda made a three cylinder motorbike with 180° crank offsets, but motor cycle designers plough their own furrow. A well known brand that fires on the 1st and 4th beat of every 8-beat bar has a fiercely loyal following.)

A similar argument explains the smooth starting of a three cylinder engine. At low speeds, and with no early cut off, the pressure in the cylinder is roughly constant throughout the stroke, so the the torque applied to the crankshaft is roughly sinusoidal. Zero at the start of the stroke, rising to a maximum halfway, and falling to zero at the end. Then steam on the other side of the piston takes over and we get another positive half cycle, so the torque from one cylinder is a rectified sine wave. Put three of these together at 120° offsets and they add up to a constant torque.

Quote from: Jim Easterbrook on April 01, 2025, 07:47:27 AM... so the torque from one cylinder is a rectified sine wave. Put three of these together at 120° offsets and they add up to a constant torque.

Absolute twaddle! "Rectified" functions are a pain to think about so here are some graphs.

Two cylinders: red & blue are torque from each cylinder, yellow is their sum. This shows the starting torque falling to 71% of maximum four times per revolution.


Three cylinders: red, bliue & yellow are torque from each cylinder, green is their sum. This shows the starting torque falling to 87% of maximum six times per revolution. Better, but not perfect.