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Going Loco

BLOG - A closer look at our collection of historic locomotives

With a collection of locomotives dating from Victorian times to the 1960s, there's plenty to discover.

 

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FRIDAY 7 AUGUST 2020

Prairie Pondering, Part 1 - Primary Prairies

While it sounds like something that should be introduced from horseback by someone wearing a Stetson, armed with a six-shooter that says ‘y’all’ a lot, the GWR Prairie is quintessentially English. The word Prairie here does not refer to the setting of a movie staring John Wayne / Clint Eastwood / Kevin Costner (delete as applicable to suit your vintage!), but to the 2-6-2 wheel arrangement.

There are two main varieties of GWR Prairie type locomotives - small and large and we will begin the first of our 3 part prairie series with a look at the history of the large ones. The story is quite complex but it starts, as most twentieth century GWR types do, with George Jackson Churchward in the early 1900s. The series of prototypes that he experimented with at that time included a 2-6-2 tank engine, completed in 1903. No. 99 had an extended trial period to really perfect the design - a common occurrence for Churchward’s experiments. This was a reasonably large tank engine - by U.K. standards at least. It was 41 ft (12.5m) long and was fitted with the latest in water boiling technology of the time - the Standard 2 Boiler. It weighed just over 72 tons fully loaded. It also had quite large driving wheels for a tank engine at 5 ft 8 in (1.72m)in diameter. All this enabled it to attain a good mix of reasonable speed, acceleration and power.

The intended duties for the design was as a mixed traffic locomotive for trains not requiring very high speeds. They however ended up proving themselves suitable for a wide range of duties in service. This early locomotive looks a little different visually to the 2 examples we have at Didcot but under the skin, a solid foundation had been laid. This is where the twisting and turning starts - in the production machines. There was a dizzying range of building, modifying and rebuilding going on, renumbering them to try and keep up with the changes too* There ended up being the original 31XX Class which became the 51XX Class, some of those eventually became rebuilt to become the 81XX Class. The 3150 Class was an updated version of the old 31XX Class with larger boilers and some of those got rebuilt and renumbered to become a new 31XX class... It makes the whole thing a bit of a pain to wade through frankly. However we have done the wading so you don’t have to!

All you really need to know is that Churchward’s successor, C. B. Collett (as he so often did) thought “that’s working very well - let’s update it all a bit.” With it’s new features including increased coal and water capacity and even a new, sleek looking lowered roof (do we sound too much like a stereotypical dodgy car salesmen?), it was just what the railway wanted. So successful was the new 5101 Class that it was built in various batches from 1929, until 1949. There were 140 of these engines built and they used the 51XX numbers that were not already in use and Nos. 4100 - 4179.**

Our survivor from the class is No. 4144 and she is of 1946 vintage. She has a fairly humble history, her most interesting duty being as a banking and pilot locomotive to help heavy trains get through the Severn Tunnel. The tunnel takes a relatively steep dive and then a matching climb the other side to get far enough down to get under the river. It can be challenging for both crews and their locomotives. This is why at each end of the tunnel, help was provided. On freight trains the extra locomotive would simply push from the rear of the train which was known as banking. On passenger trains, the assisting engines were usually put on the front and coupled up and these were known as the pilot. As you can imagine, steaming back and forth though what is essentially a tube, did not do much to promote cleanliness on the outside of the locomotive. It probably didn’t do much for the health of the crew either...

She was withdrawn in 1965 but was fortunate enough to have been purchased by a Mr Dai Woodham and sent for a little seaside holiday at Barry Scrapyard. She languished here until rescue in the form of the GWS materialised in 1974. The restoration to traffic was completed in 1997. She made a foray out to London Transport tracks in 1998 as part of the Steam on the Met gala and showed her colours, keeping pace with the rigours of the timetable of the electric trains she shared the tracks with.

A second overhaul in preservation commenced in 2010 and was finished in 2015. During this overhaul it was realised that the boiler No. 4144 was preserved with was one that had been used on a locomotive that used it operating at the higher pressure of 225 psi rather than the 200 psi she had in service. As there is no reason why the locomotive cannot handle it (more of this next time) and the boiler inspector was happy to support it, we opted to certify her boiler at this pressure. It gives her a little more strength and faster acceleration capability from a standing start which is always useful in preservation. You don’t need the top end speed it offers, but when she goes out on a run to other railways, that extra 25psi margin has been warmly welcomed by her crews. She went to the Severn Valley last year for the season and was allowed to stretch her legs a bit for once. A process much enjoyed by all.

 

At the time of writing, No 4144 is taking a rather more luxurious holiday than the Welsh one(!) courtesy of our friends at the Kent & East Sussex Railway although, being 2020, the amount of use she is getting has been somewhat curtailed... It’s quite pleasant to note that a locomotive that spent so much time doing hard graft in dirty conditions and generally being out of the limelight (and the sunlight for that matter), has found a role and gained popularity in preservation. She perhaps truly is the closest thing we have in the shed to a mechanical Cinderella...

*No. 99 herself was extensively rebuilt over the years and renumbered 3 times It was known as No. 3100, No. 5100 and lastly No. 8100. Sadly, she was scrapped as late as 1962 - even in her much rebuilt form, a genuine Churchward prototype would have been most welcome in today’s preservation collection. You can’t have everything...

**Why didn’t they go straight to 61XX I hear you cry? Well, there was already a class of 70 engines carrying those numbers. Tune in to further posts to hear about them...

 

FRIDAY 31 JULY 2020

All hail the King!

So, it’s the last summer season prior to the end of No. 6023 King Edward II’s boiler certificate. (For those that don’t know, even when an engine has been restored, the boiler has to be taken out of the frames after 10 years for thorough inspection and testing.) Where HAS the time gone?! We thought that this week we would pay tribute to what has fast become the mighty ‘Blue King’ in the consciousness of UK steam fans.

The 6000 or King class came about in a really weird way - frankly it was through PR! The Great Western’s Castles had been the most powerful passenger locomotives in the U.K. This record was overtaken in 1926 by the Southern Railway with their Lord Nelson class and Sir Felix Pole (GWR General Manager at the time) wasn’t prepared take this lying down!

The problem was laid at the feet of the GWR’s Locomotive Engineers. They had already taken the powerful (for the time at least) Star class and updated it to create the Castles. In being asked to beat the Southern Railway, they just did the same thing again. An even larger boiler, larger cylinders and smaller wheels took the tractive effort (pulling power) of the Castles at 31,625lbs and boosted it to an astonishing 40,300lbs. They threw everything at it and took the design to its absolute extreme. Surprisingly, it worked very well indeed.

The 30 Kings were built in 3 batches between 1927 and 1930. The Kings became so much the figureheads of the GWR that No. 6000 King George V was sent on tour to America where it caused something of a sensation. That locomotive is now part of the National Collection, but not in working order. It is said by some that to match the Castle, Halls and other building theme names they were originally going to be called Cathedrals but the No. 6000’s overseas holiday caused a bit of patriotism to break out! They settled down to a regular diet of the GWR’s heaviest passenger trains and they excelled at it.

This is however a design pushed to its limit. Next time you see a GWR 4 cylinder engine, take a look into the little window where the rocking arms go through the frames, just in front of the outside cylinders. In there, there is a full set of Walschaerts valve gear AND 2 more cylinders along with their connecting rods, cross heads and cranks. There is NO space wasted at all! The larger cylinders of the 6000 class were so big originally in fact that the front wheel bearings on the bogies had to be moved from the insides of the wheels to the outsides, hence their unique look.

This compact design makes maintaining and indeed just oiling up a challenging process. The King is the ultimate expression of the GWR 4-6-0 design in terms of power but it doesn’t help this issue one little bit... The other consideration that is unique to the Kings in GWR express passenger locomotive design is the sheer weight involved. They were merciless on the track they used as they had an axle weight on the main driving wheels of 22 tons 10 cwt fully loaded. Even the Castles kept this under 20 tons. This was their Achilles’ heel and it severely limited their sphere of operations. Castles were able to traverse nearly 50% of the GWR network but the Kings were limited to less than 15% of it. This meant that despite being able to handle pretty much any train assigned to them, there were plenty of places where a King simply couldn’t go.

By the post WWII era they were being fed a diet of fairly poor coal and this didn’t suit the monarchs very well at all. Performance was suffering. In a Pacific or 4-6-2 design (which most of the later UK passenger designs were) the wide firebox makes them a little less susceptible to poorer quality fuel. In the GWR 4-6-0 types, the firebox is narrow as it has to fit between the rear driving wheels so problems arose. In 1947 experiments were undertaken to improve the situation. This resulted in them being fitted with a much bigger 4 row superheater. This managed to pull even more of the energy from the burning coal and gave the Kings back their power. This was supplemented further from 1955 with the addition of double chimneys and this enabled them to retain their top position until the diesels took over their duties in 1962.

Our very own No. 6023 King Edward II (or Spud 2 as it is sometimes affectionately known - think about it!) was built in 1930 and worked for most of its life from Newton Abbot and Plymouth Laira Sheds although his last shed was Cardiff from where he was withdrawn in June 1962. A quirk of fate saved both No. 6023 and its classmate No. 6024 King Edward I. They had both been sent to Swindon to be cut up. However, the weight testing of a new bridge needed some heavy things to be put on it. We know where this is going, right? The locos were then far closer to Barry Scrapyard than they were to Swindon so it was easier to sell them to Mr Woodham to get rid of them. Funny old world isn’t it?!

6023 at Barry - Photo Tom Curtis

At Barry, a derailment in the Yard caused the scrap men to cut up the rear wheels rather than spend time putting it back on the rails. This meant that until 1985, he was considered as a restoration ‘mission impossible’. Thankfully Harvey’s of Bristol bought the loco and restoration began using a government backed manpower scheme but this came to an end in 1988 and work on the engine stalled. The locomotive was then purchased by the Great Western Society to join the outstanding collection at Didcot.

 

The GWS decided to return the locomotive to close to its original appearance look with a single chimney but retaining the 4 row superheater. The crowning achievement (pun intended) of the restoration was that in 1994, a new set of rear driving wheels were cast. 6023 finally moved under his own power again on 20th January 2011. It was originally intended for ‘KE II’ to run on the national network but the ability to reach wider and more diverse audiences and generate income more reliably by running on other heritage railways around the UK means this is the preferred avenue to secure the long-term future of the locomotive. Other considerations were the opportunity for our own volunteers to play a part in these operations – something that isn’t possible on the modern main line network – and for many of our members to travel behind the engine.

6023 during a viistit to the Paignton & Dartmouth Steam Railway - Photo Robert Sherwood

To facilitate the main line running, a lowered version of the cab roof, chimney and safety valve bonnet had been created but the originals had been retained. Earlier this year, the originals were refitted so the engine now has the same outward appearance he would have done in the late 1940s/early 1950s. There is a limited opportunity for you to come and see him in action in his full height guise. Make a date to say farewell to our mighty monarch at a Summer Steam Day or during the Bank Holiday Steam Up.

So is that it for the big blue beastie? No - not in the least! Next year is the Great Western Society’s 60th Anniversary and the King will be on display as an integral part of our celebrations. After that, we will look at the funds available and how other projects in the workshop are progressing and decide on the next chapter for this truly iconic locomotive.  Watch this space...

 

FRIDAY 24 JULY 2020

Auto Working Wonders

There are lots of different things that are quintessentially Great Western. The green and black paint scheme, the copper capped chimneys and the brass safety valve bonnets are all easy to mention. Another thing that is often thought of as ‘very GWR’ - particularly due to its associations with the bucolic branch lines that are so well remembered - is auto working. Is it something to do with a car in running condition? Let’s find out...

Get it?

Auto?

Working?

I’ll get my coat...

Auto working is the system that is set up in order to enable you to drive a steam locomotive from the other end of the train, in a separate cab, in the last coach. This avoids the need to uncouple the loco, run it round to the other end of the train and then couple it back up in order to return from whence you came. A definite time saver. While it is synonymous with the GWR, the vast majority of U.K. railway companies had at least a few routes that had auto working vehicles on them. It began in Britain around the start of the 20th Century and was certainly all over the U.K. by the 1920s. The GWR system has 4 control connections between the coach and the locomotive.

The first, and most obvious, is the vacuum brake. The great thing about the vacuum brake is that letting air in at any point along the pipe that goes from the front to the back of the train (cunningly known as the train pipe...) will cause the brakes to come on. All you have to do therefore is to put a regular brake valve in the coach and the driver can stop the train. Simple! There is one drawback here. If you are in a situation where you had to slow down for a bit and then speed up again. If the driver is in the cab in the coach, he can’t operate the ejector to create a new vacuum and take the brakes off again. This can only be done in the locomotive cab. More of this later.

A wise man once said “if you have worked out how you can stop it, you can then safely start it moving.” The second system is therefore the regulator. The regulator valve in a steam locomotive serves the same overall purpose as the accelerator pedal in a car. When in auto working mode, the lever normally moved by the driver is hooked up to a series of linkages, rods and special sliding universal joints. The cab in the coach has a second regulator lever in it and as the one in the coach moves, the one in the loco cab moves with it.

There are a couple of restrictions with this. Firstly, you can’t go round curves that are too tight. They have a nasty habit of opening the or closing regulator for you(!).

Photo: H C Casserley

 

The other issue is that there can only ever be up to 2 auto coaches on either end of the engine. This is because while the mechanism can cope with most conditions, if you put a third auto coach on, you end up with so much slack and uncertainty in the mechanism that it’s operation becomes very imprecise. As a safety critical system, this is recognised as being highly undesirable... The longest GWR auto trains therefore had two coaches, then the engine, then two more coaches. A sort of ‘loco sandwich’ type of affair if you will!

Here comes another issue - as you may know from our blog on the basics of valve gear, the engine has a mechanism that is used very much in the same way as a the gears in a car are used. This is known as the reverser. This also can only be operated from the locomotive cab. Again, more of this later.

The third system is the whistle. This is a really simple fix. There is a long steel wire that goes from the coach cab to the loco end of the coach. There is a of sort of ‘quick release’ (for want of a better term) connection between that and a similar wire on the loco. The wire on the engine is connected to the whistle lever normally used in the loco cab. Doesn’t get any easier than that.

One mistake made on occasion by loco crews was to uncouple all the connections between the loco and the coach except the whistle. It is up near the roofs of the vehicles so isn’t obvious if you are tired or being rushed. As the loco pulled away, a sort of ‘toot-snap’ noise occurred followed by coarse to industrial grade language. As the whistle was a long way away from the driver when he was in the coach cab, there is a cast gong that is operated by a foot pedal as a secondary warning device.

The astute readers among you will of course be realising that the driver needs to operate a lot of controls that he can’t operate from the coach cab. This is where our final connection comes in. The is an electric bell that operates between the two cabs and is the fourth and final connection. The code is really simple.*

1 Ring = START (the driver wants to get the whole train moving)

2 Rings = STOP (the driver wants to wait stationary for a bit)

3 Rings = BRAKES OFF (that bit we mentioned where we have had to slow down for a bit but now need to blow the brakes of and speed up again)

The other point about this is of course that not only do the driver and the fireman have to be in tune with each other, it also means that the fireman has to be quite skilled. He is doing about a good chunk of the operations in the cab that the driver would do on top of his normal tasks. Reverser and ejector are just two...

There are a number of examples of this remarkable technology for you to discover at Didcot which chart its entire development from the early 20th Century. Locomotives Nos. 1466**, 5572 and Railmotor 93 along with auto coaches Nos. 92, 190 and 231 give an amazingly complete picture. Oh, and as you marvel at the beautiful craftsmanship and ingenuity of our forbears, spare a thought for those poor overworked fireman...

 

*When in operation at DRC we use a slightly modified code system to suit the very specific needs and situation we have at Didcot. Our codes are:

2 Short Rings = take brakes off

3 Short Rings = sound locomotive whistle

1 Long Ring = Emergency Stop

5 Short Rings = driver leaving driving compartment.

 

**1466 is currently undergoing overhaul and we plan to have her back in action for the Society's 60th Anniversary in 2021 - read more and find out how you can help.

 

FRIDAY 17 JULY 2020

Decoding An Engine

 There are lots of different numbers, codes and so on associated with steam locomotives. Wheel arrangements, part and drawing numbers alongside the number that gives the engine its identity are all obvious examples. However, GWR engines have a further set of codes and symbols that are to be seen on them. Here’s what at least some of them mean.

 

Show Me The Way To Go Home!

We promise not to break into song... Each steam locomotive would have been allocated to a running shed and the manager at the shed would be quite annoyed if their locos went out on a train and didn’t come back for months. It makes life difficult for him. So, much like tagging and chipping a dog in the modern era, steam locomotives had their mark on them. The GWR and BR each had their own system.

 Painted Letters: The exact starting date for this practice is unclear (there is a list of the codes dated 1902), but it really took hold as common during the Great War. At this time, the codes they displayed referred to the division (the local area locomotive management centre, eg London or Bristol) to start with. Later on they turned into the format we see today on many of the locos at Didcot. These tell you which shed the engine calls home.

 The first way of showing this information was with metal plates on the cab-sides although this quickly changed to being painted on the inside of the cab roof. As this wasn’t easy to see from the ground at engine sheds, it was moved to the area just behind the front buffer beam. There are variations on this - painted on sandboxes being an example. The codes we see at Didcot are usually 3 letters and are an abbreviation of the name of the town or city nearest to the locomotive’s home shed. So Didcot would become DID. Examples for you to discover on the Didcot collection include:

PDN: [London] Paddington - otherwise known as Old Oak Common.

STJ: Severn Tunnel Junction

 

TYS: Tyseley

GLO: Gloucester

OXF: Oxford

 

SaLoP: Shrewsbury - later changed to SLP

SAL: Fictional - this is on 0-4-0 No.1 Bonnie Prince Charlie. It was preserved and owned by a team who came from Salisbury before it became part of the DID fleet.

  

It has to be said that the Pendennis Castle Restoration Team have had a 2 letter shed code chalked on one side of No. 4079s buffer beam for most of the time they have worked on it. The code? OZ...*

 

The full list of GWR shed codes are here: www.greatwestern.org.uk/

Oval Shaped Signs Of Change: After British Railways was formed in 1948, many practices were standardised and shed codes were one of them. They settled on the system used by the former London, Midland & Scottish Railway (LMS) which consisted of an elliptical cast iron plate that usually lived just below the handles on the smokebox door. This was an Alphanumeric system. The numbers gave you the division and the letter the home shed. So, Didcot was in the London Division and the number for that was 81. The letter assigned to it was E so Didcot became 81E. Examples you might see on the collection include:

83D - Newton Abbot Division, Plymouth Laira Shed

86A - Newport / Cardiff Division, Newport Ebbw Junction.

81F - London Division, Oxford Shed

 

There is a full list of the BR codes here:

https://en.m.wikipedia.org/wiki/List_of_British_Railways_shed_codes

Circular Thinking

The next obvious feature painted on the cab sides of some of the locomotive collection at DID / 81E (are we learning?!) are the little circles. These are what is known as the route code discs and the colour relates to how much weight the engine puts down on its axles. The heavier the highest axle weight is on the locomotive, the fewer lines they can travel down. The main routes of the GWR were built to handle nearly anything that the locomotive department could use on them but some secondary and most branch lines (exceptions in both categories) weren’t as heavily constructed. The infrastructure on them simply couldn’t handle the higher weights so those engines were banned from those lines. The route code disc on the side of the cab was a really easy way to tell without referring to books and ledgers. If it’s a blue route, you can’t send a red or double red engine down it. Simple! If an engine didn’t have a route code disc, it was light enough to send anywhere. The codes were:

No Disc - up to 14 tons on any one axle

Yellow - up to 16 tons

Blue - up to 17 tons 12 cwt

Red- all engines over 17 tons 12 cwt except the Kings

Double Red - 22 tons 10 cwt. This was only the King Class. This limited these engines to just 14% of the GWR network. This explains why there were 30 of them and 171 Castles...

  

Just to complete the picture, the breakdown of the network map was:

Hatched Red -All engines allowed. 14% of the GWR network or 522 miles (839.899 km)

Red - All engines except Kings. 34% or 1280 miles (2,059.52 km)

Dotted Red - Red Route engines permitted but at no more that 20 mph (32 km/h) 8% or 285 miles (458.565 km)

Blue - 9% or 320 miles (514.88 km)

Dotted Blue - Blue route engines allowed but at no more than 25 mph (40 km/h). 4% or 150 miles (241.35 km)

Yellow - 18% or 695 miles (1,118.255 km)

Uncoloured - 13% or 495 miles (796.455 km)

Letters Inside Coloured Circles

This system, like the route codes was begun in 1919. The coloured route code circles sometimes have letters inside them. These refer to how ‘strong’ the engine is. The amount of pulling power a steam locomotive has is measured in pounds (lbs) of tractive effort. The figures were approximate but accurate enough for their purpose and ensured that engines not up to certain tasks didn’t get put on the wrong train. Again, simple! If it was a power class D train, don’t send a power class B loco to pull it. The letters were assigned as shown here:

No Letter - up to 16,500 lbs Tractive Effort

A - 18,500 lbs

B - 20,500 lbs

C - 25,000 lbs

D - 33,000 lbs

E - 38,000 lbs

Special - above 38,000 lbs

The ‘special’ rating referred to the Kings (40,300 lbs) and strangely this also meant no letter (it would have been F) but as they had 2 red discs, We guess that they felt that it was obvious enough that the loco didn’t have a tractive effort below 16,500 lbs. Ok, the fact that the engine was a 4 cylinder monster that weighed nearly 140 tons with a full laden tender was a bit of a give away too...

 

X marks the spot?

There are sometimes a letter ‘X’ present, painted in white on the cab side. This is a system that was initiated during the Second World War. In some circumstances, certain locomotives can pull trains that are above the rated weight for their type. This system continued post war and throughout the Western Region BR steam area.

The Seemingly Random ‘W’

The random ‘W’ appears on just a few

locomotives that received any of the very early British Railways liveries. It was there due to an initial attempt at unifying the locomotive numbering systems of 4 different railways (the GWR, LNER, LMS & SR). Rather than renumber everything, the plan was to put prefixes on everything to denote the region. There was W for ex GWR, S for ex SR, E for ex LNER, and M for ex LMS. There was also an S for the Scottish region of BR and a number of others such as P for ex private owner wagons.

For the other rolling stock on the railways - the freight and passenger vehicles - this worked fine. Freight wagons got a region prefix to their number. Passenger coaches got a prefix which showed on which region it was constructed. They also got a suffix which denoted the region they worked in. With the new British Railways, this could be different.

For locomotives, it wasn’t found satisfactory. There are a few photos of locomotives of all regions running round with the various prefixes on. The cab side numbers were mostly painted on for the other railways but the GWR had maintained its corporate look for a LONG time and all their locos had metal number plates in either brass or cast iron. So, Swindon’s solution was to add the little W. In the end, BR decided to make the numbers start with the ex-GWR engines - that way the massive task of removing the cast plates or casting new ones could be avoided - and simply(?) renumber the engines from all the other railways.

When you do the ‘deep dive’ like this, there is always another layer to discover. It just illustrates the fascinating history that our engines represent. It’s much like the collection of loco numbers on the components that make them up (see Going Loco Archive), it’s a history that is not obvious. It requires you to know where to look and to speak its language. Once you can do that, you find that objects like the locomotives in our fleet are shouting that history out at you. You only have to be able to listen. So, the next time you are able to visit Didcot, see what they have to say...

 

*OZ if you don’t know refers to the fact that No. 4079 spent well over 20 years in Australia as a preserved engine. Hence Oz

 

FRIDAY 10 JULY

Are you a single?

As the late, great Douglas Adams once wrote - Don’t Panic! The last thing you all need is relationship advice from a bunch of greasy steam locomotive engineers. The title is rather more interested in the fact that a great many of the early locomotives - particularly the passenger locomotives - were single wheelers. The 3 replica broad gauge engines in existence, North Star at Swindon and Iron Duke and Firefly at Didcot are all singles. They all have just one axle that is driven by the pistons. The wheels that were fitted to that axle are BIG. The largest on record that saw any thing like regular service in the U.K. were 9 feet (2.84 metres) in diameter!* These engines were designed by James Pearson in 1853 and as they were on the Bristol and Exeter Railway, they became GWR stock as the company was absorbed by the Great Western in 1876.

The impact of all these amazing machines cannot be understated. The difference in travel speeds are like the difference between sea and air travel across the Atlantic. The average horse can cover between 20 or 30 miles (32 - 48 km) in a day. It’s about 118 miles (190 km) between London and Bristol. This could take a while, but it was a fact of life in the 1800s. The original Firefly was constructed in 1840. She is recorded as having travelled between Twyford and Paddington in 37 minutes in the year of her construction.

That’s about 30 miles.

In just over half an hour.

Not a day.

Firefly, Iron Duke, North Star and their single driving wheel sisters across the UK took the rule book and not only re-wrote it but tore it up, threw it away and demanded a fresh start. In a time before the railways, the local populace measured time based upon when the sun was at its highest point in the sky. That was mid-day. This is different depending upon how far east or west you are stood. The difference in local time between London and Bristol for example is about ten minutes. The speed and distance travelled by trains meant the country had to standardise time itself so that 10:00 was at the same time everywhere in the U.K. Think of it this way, the railways of the 1840s redefined how you, today, think about time itself.

So, we know they were amazing but still, why the big 7ft (2.13 metres) diameter single driving wheels on Firefly? Well, there are a few parts to that question. Firstly, we need to talk about the speed of revolution. The faster a locomotive goes, the faster the wheels have to spin in order to do it. Take a wheel with a small diameter and a wheel with a large diameter and put them on the same starting point on flat ground. Roll the wheels so they go through one complete revolution. The smaller wheel will have travelled less distance than the larger wheel. This is because the circumference (the distance round the outer edge) of a large wheel is a lot bigger than a smaller one. So, one turn of the wheel gets you further. You don’t have to turn the axle that fast in order to get the engine moving quite quickly.

This fact has massive benefits in many other areas of the engine. Although it takes a while to get up to speed, once you are there, the amount of steam you are using is less because the pistons are travelling backwards and forwards much more slowly than if you had small wheels. Keeping what is known as piston speed down is a good thing. This means that the overall size and weight of the locomotive can be less because the boiler doesn’t need to make as much steam and can be smaller and the amount of water and fuel you need to feed it is less too. The engineering can be lighter as the mechanisms that drive the engine do not need to withstand such large forces. Equally important is that you have to realise how much development has been made in lubrication technology between then and even the early 1900s. Back then oils and the way you delivered it to the moving parts of a locomotive was very different. The cleverly synthesised steam and lubrication oils and even the means to reliably deliver them were things of the future. The hotter these earlier oils got, the more it breaks down and the less effective it was. Make the parts move more slowly and reduce the friction, you reduce the heat and reduce the potential of the oil failing to do its job. Remember too that these guys used to fill oil pots on the move at 50+ mph or 80.5kmh. Think about that...

So, if massive single driving wheels are so great, why don’t ALL fast steam locomotives have 9ft+ single driving wheels? Well, the trains they were pulling in those days were much lighter for a start. As trains got heavier, the possibility of that single driving wheel slipping became greater. A loss of grip at a single point on greasy rails meant that you might not even be able to get the train moving out of the station. The engine can only put down so much weight on that one axle to enable you to grip the track and pull the train. Another point (amongst MANY others) is that the bigger you make the wheels, the less room you have for things like the boiler. You can only make your engine so tall before they start hitting the bridges and tunnels they need to go under or through! Also, the last thing you need is a spinning axle in the middle of the space where a sealed pressure vessel needs to go... Split, 2 piece boilers, mounted around axles were tried by the French on an experimental engine called L’Agile (The Eagle) in 1855. This engine had four 9ft 4in (2.845 metres) wheels but the joints between the two bits of the boiler were a nightmare to keep steam tight and there were not enough space for lots of fire tubes in the boiler to heat the water so it couldn’t keep its cylinders fed with steam at speed. So even if you have more than one set of massive driving wheels, there are other factors which stop you using them.

Despite a brief renaissance after the invention of steam powered gear to lay sand on the track to help with grip, the writing was on the wall for these paddle steamers of the rails. The age of the single wheeler was pretty much over by 1900 as the rest of steam locomotive technology had caught up. Multi driving wheel machines of the 4-4-0 , 4-4-2, 4-6-0 type and beyond took over and the vast majority of these earlier machines were lost to history. In 1910, a brave last stand of the single design was made in China of all places. The Shanghai - Nanjing Railway ordered four 4-2-2 locomotives weighing 120 tons (pretty much the same as a GWR Castle!) with 7 ft (2.13 metres) driving wheels from Kerr Stewart and Co. in Stoke-on-Trent. In their bright Imperial Yellow livery they must have been quite a sight. They were also the last Singles built for day to day service (not replicas like Iron Duke and Firefly) in the U.K. The last few remaining British designs eked out an existence until the 1930s. At the time of writing, there are no operational full size singles in the U.K. The last being our Firefly replica in 2015. This is a shame, there is a real something undefinably elegant about the grace of those huge wheels turning. There are a few other non-GWR singles in existence. Examples include, The Midland Class 115 ‘Spinner’ No. 673, Caledonian Railway 123 and GNR No. 1 - the Stirling Single. However, these are all safely ensconced in museums and are unlikely to be allowed out for overhaul in the foreseeable future, if ever. Our Firefly however, will one day return.

Fire Fly and Iron Duke are both on display along with replica Victorian coaches on all of our Open Days.

*The absolute record diameter of wheels on a steam locomotive is also held by a GWR machine. The 10 foot (3 metre) diameter wheels of the 1838 Locomotive known as Hurricane. Why don’t we shout about it? It was singularly one of the worst designed locomotives of all time. Even if you make allowances for the pioneering nature of the age it was still a really dumb idea. We will have to all have a quiet chat about it sometime. We promise we won’t talk about it elsewhere if you don’t...

 

FRIDAY 3 JULY

Award Nomination for Saint

We were delighted to hear a couple of days ago that our “Saint” project has been shortlisted in the Restoration/Conservation Project category of the annual Museums & Heritage Awards coming just as they prepare to re-open following lockdown.

The prestigious nomination recognises the hard work and dedication of volunteers at the Centre who toiled for almost 24-years to raise funds and then physically deliver the £825,000 project to build 2999 ‘Lady of Legend’.

The team are in great company in the national awards: other shortlisted projects in this category come from the Palace of Westminster, Chatham Historic Dockyard, The Box at Plymouth and Aberdeen Art Gallery

Appropriately, then, this week’s blog provides a little more detail on this colossal project . . .

No 2999 “Lady of Legend” is a recreated Saint Class locomotive of the type introduced by the Great Western Railway in 1902.

The innovative, outside cylinder design was the work of George Churchward, the GWR’s newly-appointed Locomotive Superintendent and incorporated features such as long-travel valves which greatly increased efficiency.

The Saint class performed extremely well, and the design formed the basis for the period of standardisation on the GWR that lasted nearly 50 years until the railways were nationalised in 1948. This unprecedented half century of design continuity, built on the foundation of the Saints, is depicted through the unparalleled collection of locomotives assembled by the Great Western Society at Didcot which includes examples of most GWR types from this era.

Until 2019, the most significant exception was the Saint Class itself as the last original examples were withdrawn and scrapped in 1953, long-before the railway preservation movement was established.

This gap was identified early in the Society’s history and the Centre has long held an ambition to create a working Saint to help demonstrate the GWR story to its visitors.

That ambition came to fruition in 2019 with the completion of a project, 45 years in the making, to build locomotive 2999 using parts from 4942 “Maindy Hall” (one of the classes developed from the Saint design).

Lady of Legend entered service in April at a special ceremony performed by celebrity chef Pru Leith.

The widely held passion for the elegant and efficient 'Saints' meant that many dreamt of creating a new member of the class to showcase Churchward’s pioneering design.

For decades, it was considered to be beyond the capability of preservationists and prohibitively expensive. However, restoration of No. 6023 “King Edward II”, which among other things involved construction of a new driving wheel set, proved that the Society could successfully undertake major reconstruction and refurbishment projects, and the Saint Project was born. 

The scheme centred on rebuilding No 4942 “Maindy Hall” from scrapyard condition and reverse engineering the locomotive to create a Saint. This mirrored the process the GWR had used in 1925 when the prototype Hall Class was produced by the conversion of “Saint Martin”.

No. 4942 had been purchased in the early 1970s with the specific purpose to recreate a Saint but early attempts floundered and the prospect of success remained a dream until 1995 when the project started in earnest.

Major new components that have been manufactured include three new driving wheel sets, as the Halls had 6ft drivers while the high stepping Saints sported driving wheels of 6ft 8½in diameter.  Two bogie wheel sets were cast to the correct 3ft 2in size and two identical 'half' cylinder blocks were cast to recreate the inside cylinders fed by a straight steam pipe that was integral to the Saint design. The lever reverse was also made from scratch while the frames from No. 4942 were extensively modified and strengthened.

Many other components, including the boiler, were refurbished, while still more came from surviving parts from other GWR locomotives – further testament to the far-sighted Swindon practice of standardisation.  Parts include a connecting rod from 2906 “Lady of Lynn” and the whistle from 2910 “Lady of Shalott” and the chimney from a 68XX Class.

The new machine has been numbered 2999, taking the next number in the sequence allocated to the Saints – the previous one, 2998 “Ernest Cunard”, having been outshopped in 1913!  The winning entry in the competition to name the locomotive was “Lady of Legend” as it evokes the GWR practice of naming early members of the class after mythological or historical ladies.

The recreated Saint has been built with straight frames so that it can also run as an Atlantic 4-4-2, as Churchward did in the 1900s. Rear extension frames have been constructed, trial fitted and placed into store.

The £825,000 project, funded entirely by donations and bequests, means that over a century since the previous member of the class was built, an example of Churchward's iconic 20th Century design, which influenced almost all subsequent British steam development, is back on the rails to delight, inform and entertain 21st Century visitors.

The engineering excellence that went to create 2999 was recognised by the Heritage Railway Association in February when the project won the first-ever Chairman’s special prize at the organisation’s annual awards.

We believe the foresight, tenacity, craftmanship and above all determination of the GWS and the volunteer team make this project worthy of an award – we’ll be biting our nails until the winners are announced on 22 September!

2999 will take pride of place in front of the Centre’s iconic Engine Shed as visitors return to the site for a series of Open-Air Discovery Days this month. Visitor numbers are strictly limited and tickets must be booked in advance.  

  

Social distancing will be vital as the Centre re-opens!

 

 

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