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Going Loco - June 2020


Is Everyone Still All Whyte?

Let’s finish off our look at the Whyte System. As a reminder, the first number is the carrying, unpowered wheels at the front, the next number is the powered, coupled wheels in the middle and the last number is the carrying, unpowered wheels at the back. The notations sometimes have names and last time we looked at such things as Branchliners, Bourbonnais and Olomanas. These notations can be quite small. For example, Stephenson’s Rocket can be described as an 0-2-2. No carrying wheels at the front, 2 driving wheels and then 2 carrying wheels at the back. They can get quite long too. The LNER built a single example of the U1 class which was of the Garrett type. This revelled in the wheel arrangement of 2-8-0 + 0-8-2. The Garrett type being an engine that has a single large boiler mounted on what amounts to two separate locomotive chassis with their own wheels, cylinders and motion.

For extra fun, there have been engines with wheel arrangements as bizarre as 2-8-8-8-4 (three sets of coupled wheels - the only one being the Virginian Railroad XA Class No. 700 of 1916). Any engine with 3 sets of driving wheels can be known as a Triplex. There are also the amazing Johnston 16 wheeler geared locomotives from New Zealand logging railways. These can be regarded as either 2-2-2-2-2-2-2-2s or 2-2+2-2+2-2+2-2s. With that, back to the GWS collection.

2-6-2 (Nos. 5572, 4144, 6106): All of Didcot’s 2-6-2s are actually 2-6-2Ts (side tank type engines). This is fairly typical of the wheel arrangement in Europe but those in America were usually tender locomotives (pulling a separate vehicle to hold the coal and water). The first American tender 2-6-2s were built in 1900 by the Brooks Locomotive Works for the wonderfully named Chicago, Burlington and Quincy Railroad. These engines were mostly used on services in the Great Midwestern Prairies which lead to the name Prairie for this wheel arrangement. This is one of the American names in common use in the UK.

2-6-0 (No. 5322): This is another of the wheel arrangement names that sees common use in the U.K. The Mogul name used is of uncertain origin. Some people will tell you that it comes from an engine called Mogul that was built for the Central Railroad of New Jersey by the Taunton Locomotive Manufacturing Company in 1886. There is however a counter claim from the UK for a Great Eastern Railway locomotive also called Mogul built by Neilson & Co of 1879. Whatever the truth of where the name originated, the first tank engine 2-6-0 was built in about 1870 for the Garstang and Knott-End Railway. Now that IS a name!

4-4-2 (technically No. 2999): No. 2999 Lady of Legend has been constructed in such a way as to be able to be converted into a 4-4-2 Type. This is because the GWR did the same with some of the originals as part of a testing program in the early 20th Century. The type was first employed over the 4-4-0 types to enable the fitting of larger, wider fireboxes although this wasn’t the case with the Saints. This type is most commonly known as an Atlantic after the Atlantic City Line 4-4-2 locomotives of the Philadelphia and Reading Railroad. They are also known as Milwaukees after the fast 4-4-2 machines used on the Milwaukee Railroad.

4-6-0 (Nos. 2999, 4079, 5051, 5900, 6023, 6998, 7808): This is one of the GWR’s favourites! There were Saints, Halls, Granges, Manors, Modified Halls, Counties, Stars, Castles and Kings and they were all 4-6-0s. Other railways also had a go at a few apparently... Although the name isn’t used in the U.K., the Americans use the name Ten Wheeler to describe the 4-6-0. This is because there are ten wheels. Did I have to point that out? Probably not...

2-8-0 (Nos. 3822, 4709, 5227): The 2-8-0 is usually for freight. Nos. 3822 and 4709 are both tender locomotives but the No. 5227 is a 2-8-0T or tank engine. The GWR 28XX Class that No. 3822 is a development of was the first UK version of a 2-8-0 and set the standard for heavy freight locos in the U.K. until the end of steam (The B.R. Class 9F 2-10-0 being the main exception). The American name for this type is the Consolidation. The name coming from the 2-8-0 Lehigh & Mahanoy Railroad’s machine of 1866 which was called Consolidation. This was the first 2-8-0 to have a separate pony truck for the front two wheels rather than the leading unpowered wheels mounted rigidly to the frames.

2-8-2 (No. 7202): The 2-8-2 design was relatively uncommon in the U.K. A 2-8-2T or tank engine like No. 7202 was even rarer. They were however, quite common elsewhere in the world. The 72XX Class came about rather by luck than judgement but proved very successful. The first locomotive to have a 2-8-2 wheel arrangement was built in 1884 and called Calumet but this name didn’t stick. The name that eventually came to describe 2-8-2 locomotives - Mikado - was coined after the Class 9700 locos built for the Nippon Railway of Japan by the Baldwin Locomotive Works in 1897. The name comes from the popular Gilbert and Sullivan opera of the same name that was first performed in 1885. During the Second World War, the anti Japanese feeling in America lead to the wheel arrangement being renamed MacArthur after the famous General (despite the fact that the opera was British) but the old name returned post war and is still in use today.

Which leaves us with Railmotor No.93. Well, it’s either an 0-4-0 if you just include the power bogie as a separate locomotive or an 0-4-4 if you include the coach. Or possibly an 0-4-0+4. Is the coach a tender? It does carry the coal and water for the engine after all. Does the fact that the coach wheels does not carry the weight of the locomotive mean that we ignore them? If you include the coach then should it have the WT suffix? The tank is under the floor of the coach after all. The ‘locomotive’ is an integral part of the coach too. We will leave that one to you...


Is Everyone All Whyte?

Quite often the loco department, like anything that has been around for a while uses jargon and acronyms. Anyone who has ever watched or read anything regarding space will know what we mean. There was once a proposed device that revelled in the name OWL Telescope (OverWhelmingly Large) which was sadly scrapped in favour of the smaller ELT (Extremely Large Telescope) design. We are not making this up! Engineers are really good at adding in this sort of buzz word stuff and the most common for us at Didcot has to be the Whyte Notation System.

Frederick Methven Whyte (they don’t make names like they used to do they?) was a Dutch / American engineer born in 1865. His idea came into common use following a December 1900 editorial in American Engineer and Railroad Journal. While describing an engine as a 4-6-2 might sound complicated to the uninitiated, it really isn’t. A 4-6-2 locomotive would have 4 unpowered weight carrying wheels at the front of the engine. It would then have 6 powered or coupled or driving wheels in the middle, followed up by two more unpowered weight carrying wheels at the back. What is important to realise is that you only include wheels on the locomotive, not on the tender (the vehicle out the back with the coal and water in) if it has one. This is treated by the Whyte System as a separate vehicle and is ignored. There are lists of suffixes that get added to denote various things, some of which we will look at. There is also a whole host of names that get used to describe the wheel arrangements (a 4-6-2 is known as a Pacific), not all of these are in common in use in all parts of the world. It’s mainly an American thing but some of these names have leaked into British usage. Let’s have a look at Didcot’s collection.

2-2-2 (Firefly): The first 2-2-2 was an expanded version of Stephenson’s earlier 0-2-2 and 2-2-0 designs. The idea being that it gave you the chance to fit a larger firebox. Any loco with just one driven axle can be known as a single but the 2-2-2 design was also named the Patentee after the engine built by Stephenson in 1834 and later it was called a Jenny Lind Jenny Lind was a popular opera singer who got a 2-2-2 engine named after her in 1847. She was also known as the ‘Swedish Nightingale’ which we think should be a name for an engine if it isn’t already.

4-2-2 (Iron Duke): Another Single. Also known as, wait for it, the Iron Duke Type because of the GWR Iron Duke Class locomotives. Like our Iron Duke. Sometimes this wheel arrangement is known as a Bicycle too. You have to love that...

0-4-0 (Nos. 1, 5, 1338, 1340): When there are just driving wheels under an engine, the wheel arrangement is sometimes just referred to as a [something] coupled type, so an 0-4-0 is a 4 Coupled but this is not exclusively recognised. Sometimes locomotives with different wheel arrangements with the same number of coupled wheels are also known as 4, 6, 8, 10, 12 or (one Soviet example - it couldn’t go round corners!) 14 coupled. It’s a phrase that is used lots of different ways. The first ever steam railway locomotives - Richard Trevithick’s machines of the very early 19th Century - were 0-4-0s. This is where we start to get into the suffixes. No. 5 Shannon is an 0-4-0WT. Tank engines carry their supply of coal and water on the locomotive chassis and do not use a separate tender. Where they carry their water is what makes the difference. WT stands for Well Tank and Shannon’s water tank is between her frames, below her boiler. Arguably a well of water! Nos. 1 Bonnie Prince Charlie, 1338 and 1340 Trojan are all 0-4-0ST engines. ST standing for Saddle Tank and one look at the large round saddle-shaped water tank atop their boilers will tell you why...

0-4-2 (No. 1466): No. 1466 is an 0-4-2T. The T suffix means any locomotive that has water tanks that don’t hang off the boiler, but are mounted either side of it. These can be in a variety of shapes and may have an additional water tank under the coal bunker at the back. They are sometimes called side tanks but to avoid confusion with saddle tanks, they just get a ‘T’. The exotic name sometimes used for an 0-4-2 is an Olomana. This name refers to a little narrow gauge engine built in 1883 in America by the Baldwin Locomotive Works of the same name. It was shipped out to Hawaii and was only the third self-propelled machine to operate on the island. Its working Life was spent at the Waimanalo Sugar Company and it is preserved as part of the Smithsonian Collection, being owned and operated at one point by Walt Disney animator Ward Kimball. Walt Disney himself was a frequent driver of the machine!

0-6-0 (Nos. 1363, 2409, 3650, 3738): As with the 0-4-0, the 0-6-0 gets referred to as a 6 Coupled sometimes. The French have also been known to call them Bourbonnais which was an early locomotive to operate in their country and is named after the region of France. With Nos. 3650 and 3738, we get the last of Didcot’s different suffixes here with the most famous being 0-6-0PT. This means Pannier Tank, the 2 water tanks hanging off the sides of the boiler which in smaller locomotives, offers better access to the working parts between the frames although there are additional reasons why the GWR adopted it too (see our blog post entitled The Big 13 - Lucky For Some). Nos 1363 and 2409 are both 0-6-0ST or saddle tanks.

0-6-0 Diesels: Vehicles like Railcar No.22 and Gas Turbine Prototype No. 18000 aren’t usually described using the Whyte system as they run on separate powered bogies driven by means other than steam. The Whyte System does apply to some of our other diesel locomotives. Typically, small shunting locomotives that look more than a little like their equivalent steam locomotives. The D stands for Diesel (the type of energy consumed by the drive motor) and the next letter denotes the type of transmission. Therefore:

Class 08 No. 08604 Phantom is an 0-6-0DE (Diesel Electric)

No. DL 26 ‘The Rat’ is an 0-6-0DM (Diesel Mechanical)

Class 14 No. D9516 is an 0-6-0DH (Diesel Hydraulic)

0-6-2 (No. 6697): This is a typically Welsh design - well suited to storming up and down the valley lines they inhabited. There are 2 names associated with them. Branchliner refers to a series of American locomotives that were originally 2-6-0 tender types that had larger fireboxes fitted, necessitating the carrying wheels being moved from the front to the back. They were mainly used for branch line work, hence the name. The other name used, Webb, is in reference to the British locomotive designer Francis William Webb and his famous ‘Coal Tank’ class of 0-6-2s.

We will leave the rest of the Collection for another time as this is getting quite long enough now, so this is the first of an epic 2 - part blog! A passing thought to end on. How do we classify our Wickham Trolley No. B42W? It has a petrol powered engine, driving a mechanical transmission so the suffix is PM. Sometimes small diesel locomotives just have their number of wheels quoted so it might be that No. B42W is a 4w PM. But, you could also describe it as a 2-2-0PM as only the rear two wheels are driven. Is it a locomotive? It can pull small trailers so it can form a train. We will leave you all to figure that one out.

Part two next week... 


1363 - Survivor Extraordinaire!

We chatted a little while back about the historic significance of the ‘Big Thirteen’ (see Going Loco Archive) but what is equally fascinating is how this engine became preserved in the first place and it involves lots of people over whom No. 1363 seemed to have cast her own spell. When she was withdrawn, she had only done 18,000 miles since her last overhaul. Her last official shed was Plymouth Laira and the staff there were enamoured somewhat with this little tank engine. She had had a dent in her bunker where she had had a ‘disagreement’ with a Hall Class locomotive a few years back but to them it must have just added character! At the time there were just two surviving GWR Swindon-built saddle tank locos. No. 1363 and her sister, No. 1365 which had been shedded in Bristol but unfortunately did not have long left. This fact had not gone unnoticed. No. 1363 had been stored out of use for quite a while. She was previously used as regular loco for the Plymouth Millbay Harbour area but now sat cold with an uncertain future.

The BR staff at Laira were ordered to clear the depot of any remaining steam locos by sending them for scrapping. These were mainly ‘County’ class engines (getting one of those too would have made our current job a bit easier!), which were formed into a long line with 1363 at the head. It looked like the end. One last trip... The staff of the shed, including the shed manager, had been making every effort to keep No. 1363 under their care. She was even being maintained by them in their spare time. They were desperately looking round for a bolt hole for her and they weren’t going to let her go that easily. Unbeknown to the crew that came to take her away, the shed staff had been busy the night before. At the suggestion of a man in the know, a few key items had been removed. These were a good few of the bolts that held the front buffer beam and coupling in place. No. 1363 was the last loco placed in the train. The diesel coupled up and went to pull away. The weight of the train of dead engines and the effort of the diesel did its terrible work. There was a sickening noise of tortured metal. The front buffer beam had been torn outwards and the coupling was so badly damaged that it was impossible to tow the engine. You can imagine the conversations. Oh dear, there, there, never mind. That looks unfit to travel... Once the train had gone, No. 1363 was quickly squirrelled away in a corner of the roundhouse. Where she stayed. For about a year!

While all this skulduggery was going on, 4 schoolboys had started a group to buy a 14XX Class locomotive and its accompanying auto trailer coach. This was of course the start of the Great Western Society. At the Society AGM of 1963, it was suggested that perhaps the society (who had not yet bought No. 1466 and coach No. 231) would be better served to lower its sights and try to get a smaller, cheaper locomotive first. The suggestion was made that No. 1363 - due to its unique history - would be a much better bet. Ultimately, as we know, that idea was turned down but it had planted the seed of an idea in the mind of the then Chairman Peter Lemar. He saw the need to preserve the locomotive and along with his brother-in-law, Alan Edwards (a senior MOD engineer) arranged to inspect the locomotive. Despite having to remove the ash from the last fire, the inspection showed that the locomotive was in generally excellent condition and with a little light metalwork (to the front buffer beam!), would make for a very sound prospect for preservation. 


Peter and his wife Joan set up a separate fund to buy the locomotive and were able to raise the money in a fairly short amount of time.  They actually ended up with offers of money that totalled almost twice the asking price of the locomotive. Therefore the locomotive was purchased and became a preserved engine. The purchase had been done privately so Peter was technically the legal owner. There were a few people that had been involved in the purchase so Peter and Joan gave them a number of choices as to how to proceed with her preservation, including the backers keeping the engine themselves. The overwhelming result of this ballot was to donate No. 1363 to become part of the Great Western Society collection and as such she became just the second item of rolling stock owned by the Society, shortly after No. 1466 had be purchased.

When you hear how close to destruction this engine was on several occasions, you realise just how lucky we are to have her. You also realise what a lottery preservation is and that it was often a confluence of unlikely events that resulted in a piece of rolling stock being saved. We have a lot to thank the early pioneers of steam preservation like Peter and Joan Lemar and those guys all those years ago at Laira who were so determined to save their shed pet! Peter was instrumental in preserving a number of the vehicles in the collection and purchased some of them himself. It is really a tribute to people like him and all the other GWS trailblazers that the collection at Didcot is so wonderfully diverse and interesting. Although Peter passed away a few years ago, when we steam No. 1363 again after her overhaul, we will no doubt pause to remember him and all the others that did so much to ensure that this fascinating little engine was passed down to future generations.

You can donate to our Small Locomotive Fund which supports the restoration and maintenance of 1363 and other small tank engines at Didcot.


Under Pressure

The steam locomotive boiler is a wonderful bit of kit. It uses all sorts of clever science to make steam so we thought we would take a deep dive into the way one of these things works. Mind your head on the way in...

The first thing to say is that it is, like any machine, a device to convert one type of energy into another. In this case we start with the chemical energy bound up within the coal itself and convert it to heat energy. The chemical energy was laid down eons ago (the story of coal is for geologists to explain far better than us steam loco engineers!) and is released when a flame is applied to the coal. To put it another way, we burn it! In order for the coal to burn more efficiently, it needs to have sufficient access to air and there are two directions it can come from. Underneath through the grate or through the fire hole door, where the fireman puts the coal in. Adjusting the damper doors on the ash pan and the fire hole doors in the cab gives the fireman a pretty accurate control of the airflow into the fire. With a bit of experience course.

All this takes place in a big metal box. With a fire in it. It’s called a firebox. We locomotive types are not complicated people... there are two walls here. The inner one is made of copper on all of our GWR locomotives. Then there is a space where the water goes and this is heated by the energy coming through the copper walls. Then there is an outer firebox made of steel. On the front of this is a big barrel shaped protuberance called the barrel (again, not people likely to win literary prizes). Inside here are a number of tubes. The vast majority of these are fire tubes - the hot gases from the fire travel along their length. The water is on the outside of these and is heated by the thermal energy flowing through them.

The multi-tubular boiler is one of the greatest innovations of the steam age. Really early steam engines just had one, large diameter tube for the hot gases from the fire to pass through. Not long after this, it was realised that if you put a number of tubes of smaller diameter in the boiler instead of one big one, you increase the amount of hot surface area that the water can come in contact with. This makes it more efficient - you get more useful energy out of the coal you are burning. It was present on Stephenson’s Rocket in 1829, on the original GWR Firefly Class in 1840 and it was present when Swindon built 9F Class 2-10-0 No. 92220 Evening Star in 1960 as the last ever British main line steam locomotive. A good idea is a good idea.

There are a few really clever bits about the way a locomotive boiler works.

Clever bit No. 1: The harder you go chuff, the more air goes through the fire! That’s right - the steam comes out of the boiler, through the regulator (the steam engine equivalent of the accelerator in a car) and is used in the pistons. It is then exhausted up the chimney via a conical shaped device called a blast pipe which accelerates the steam as it goes through it. Remember the Venturi effect? This causes the air pressure in the smokebox (the black bit with the door on it at the front of the boiler, where the smoke goes through, we do like the simple names remember...) to be lowered. This causes the hot gases to be pulled through the tubes in the boiler to heat the water that surrounds them. In doing this, it lowers the air pressure in the firebox, drawing fresh air into the fire making it burn hotter! The harder the engine is working, the more steam it needs and the more steam it produces. Well, that’s convenient!

Clever bit No. 2: The firebox really should melt. The copper that all the GWR fireboxes are made of might be a special, slightly more heat resistant type (arsenical copper for those that have to know) but it melts at 685 degrees C. (1265 degrees f.). The fire however burns a lot hotter than that and indeed the copper goes soft and would therefore result in a catastrophic failure (a.k.a. an explosion!) long before that temperature is reached. Pressure likes to get out and when you are dealing with up to 250psi (King Class), it REALLY does it’s very best to escape. So, why not? Because physics! We have established that copper does not have the ability to withstand a large amount of heat energy inside itself. It IS however very good at moving that heat energy from one place to another. It is a fantastic thermal conductor. The water on the outside of the copper part of the firebox has an enormous appetite for heat energy. Ever wondered why heating a bath full of water or the water in your radiators takes so much energy? Water can absorb a very large amount of heat energy. So, the copper takes the heat energy from the fire and conducts it through itself to the water on the other side and the water absorbs that heat energy, keeping it cool and preventing it melting. Simple!

Clever bit No. 3: The superheater. This is one of these ‘two bites of the same cherry’ type deals. If you have a big loco that is required to make a great deal of steam for a prolonged period of time (say, Paddington to Bristol), every ounce of energy you can get to go to turning the wheels then the more efficient the locomotive will be. So, the steam in these bigger engines is released through the regulator valve and instead of going straight to the cylinders it goes instead back into those hot gases coming from the fire. Here is where things get weird. We have to talk about wet and dry steam. It’s all made of water - how can that be I hear you cry?! Ok - wet or saturated steam is the stuff that comes straight out of the boiler. Dry steam is also known as superheated steam and the big difference is the amount of energy bound up within it. The steam travels from the regulator, through the superheater header, into a series of smaller tubes known as elements. These are inside larger fire tubes called flue tubes. This gets the steam the second bite at the energy coming off the fire. The steam

Then goes off to the cylinders where the extra energy reduces the likelihood that it will condense in the cylinders, raising the efficiency of the engine. Think of it like a steam engine version of a turbocharger.*

There are lots more really clever bits of engineering on a steam locomotive and its boiler but rather than write something that is 30,000 words long, we will save some more for another day. To be continued.

*For some unknown reason, the little covers on the side of the smokeboxes of some GWR engines seem to have collected the name ‘superheater covers’. Quite where this idea came from is unknown, but the covers are there just to tidy up the look of some oil pipes. The superheater system itself is WAY too big to fit under them and is completely contained inside the boiler and smokebox anyhow. It does not need covering.




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