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Going Loco - November 2020


A Long Term Round Up

As we close in on the end of 2020 (thank goodness) we thought that we would look into the less travelled corners of the blog workshop. Here’s a whip round of news items about what’s going on with some of our longer term locomotive projects.

At the back of the barn there’s this owl.

4705 Exeter St Davids 1960

Ok, it’s not a barn owl, it’s a night owl and it’s in workshop in Devon, not a barn, but go with it...

To go further with the animal reference we will add a pony into the mix. A pony truck that is. The pony truck is the piece of equipment that holds the front axle in place on locomotive with just 2 non-powered wheels up front. This pony truck was originally fitted to a prairie class locomotive and as such it’s not a straight swap. With the expert skills of an engineering company as well as advice from our good friend - ‘Mr Tyseley’ himself, Bob Meanley, an extensive refurbishment and modification programme has been undertaken. This included such processes as machining the bearing faces that allow the axle to spring up and down and a whole new set of very precisely machined fixings to put the whole lot back together. The team are now confident that it will not only fit but it will as importantly perform in the way they expect it to. It will be completed very soon and put into storage ready for the re-wheeling of the chassis that should take place in the new year. Exciting stuff!

Find out More About The 4709 ‘Night Owl’ Project.

Meanwhile, on the County border...

No. 1014 County of Glamorgan has also been making massive and highly visible strides forward but, like No. 4709, not all of these have been at Didcot’s locomotive works. The one from home that got the most publicity recently was the fitting of the locomotive’s smokebox for the first time. A wonderful cover shoot with Steam Railway Magazine saw our two bookends of the GWR 2 Cylinder 4-6-0 story (Saint and County) gathered around our turntable. Trouble is that there is still quite a large gap behind there that needs a boiler to fill it! Thankfully the two halves of the boiler - the firebox from the 8F and the new front barrel section - have just been riveted together so the team are inching closer to filling it. The new front tube plate (front end of the boiler) is also ready to go in.

1014 13 August 20

Other news from No. 1014 is that the new connecting rods are in the final stages of machining. These are hugely important as they transfer the energy from the pistons to the wheels and need to be very precisely made and incredibly strong too! These mighty forged steel components are really impressive looking things...


County barrel and firebox riveting

Follow the County Project on the 1014 Website

And finally - heavy freight!*

I’ve always wanted to be able to do the and finally thing on the news!

7202 - photo courtesy of Phil Morrell

The restoration of No. 7202 has been a truly long term goal but things are continually moving forward. There is only a small team that work on this loco and the social distancing restrictions have taken their toll on proceedings this year. Despite this, the crew are very determined to see this monster tank engine steam! The vast majority of the work on the frames is now completed with just the pipework for the vacuum braking and injector systems as the last remaining ‘big’ jobs.

Therefore, the boiler remains the last hurdle. It’s a pretty old standard 4 boiler and has been around the block a few times since it was built by Ruston and Hornsby of Lincoln in 1926. The crown stays (those on the top of the firebox) are the current focus of attention. They are being slowly replaced as time in the works allows.

It requires quite a lot of steel plate replacing in the outer firebox with the majority of the throat plate (front of the firebox) going for scrap as well as the bottom of the back head (the rear of the firebox where the cab sits). A new front tubeplate is also ready to go in but all the while the work is happening on the firebox, the fact that the front of the boiler is open and accessible is pretty hard to give up! The other thing about this team is that they do all of their own fundraising too. If you can, next time you visit, throw them a couple of coins in their little black collecting box. Every penny counts!

7202 cab, Fireman's side - 23/11/20

Well, that rounds out our long term project round up (please imagine me shuffling the papers on the desk - I understand that’s traditional for newscasters...). It’s goodnight from me and it’s goodnight from him.**

*I hasten to point out that your blogger in no way likens the No. 7202 Team to the traditional ‘and finally’ story on the news. Please do NOT compare them to a skateboarding squirrel...

**Yet more evidence for how old your blogger is - these things are like tree rings aren’t they?!


An Injection of Pure Genius

(2914 Saint Augustine - steam coming from the injector overflow)

Warning: There is some massively over-simplified physics here. Whilst I appreciate that some people can tell you chapter and verse, this is a blog for a general audience. Just the basics is enough...

Steam engines need water. Water in constant supply while in steam in fact. The big problem with getting water into a boiler is that the boiler is already at pressure. You therefore have to overcome that pressure in order to get the water in. So you are already fighting an uphill battle so to speak. Early 19th century locomotives did the obvious thing and connected a water pump to the engine somewhere. The big disadvantage here was that these water pumps were connected to the mechanism that made the wheels turn. You can only therefore put water into the boiler when the wheels are revolving. It wasn’t uncommon in that pioneering age for locos to be disconnected from the train until just before the departure time so they could run up and down in order to fill the boiler. There is a multitude of drawbacks here and it clearly wasn’t a satisfactory solution.

Injector from 6023 King Edward II

The solution came along as late as 1852. This is where a Frenchman with the easily remembered name of Baptiste Jules Henri Jacques Giffard. Let’s call him Henri shall we?! Born in Paris in 1825, he made many contributions to engineering including being the first to fly in a powered controlled flying machine. His Giffard Dirigible (airship) first flew in 1852 and was powered by a 3hp steam engine. Rather terrifyingly, the gas bag was filled with ultra flammable hydrogen. With a steam engine. That puts out all kinds of hot gases, sparks and flames.


I think I’ll wait for the Wright Brothers to come along thanks.

The invention we remember him best for at Didcot however is his steam injector. This is an amazing piece of equipment that seems to work via magic as far as most people are concerned.* It seems to do the impossible in that it uses the steam to overcome the pressure of the same steam. The Giffard injector also does it with the absolute minimum of moving parts too. Sounds too good to be true. But let’s have a look.

It is described as a fluid dynamic pump. That means it is using the properties of the fluids and the energy bound up within them to provide the pumping action. No matter which way you cut it, it sounds complex, so let’s break an injector down to its four most basic components. There is the body of the injector, the big metal outside casting. Inside there are three cones arranged thusly: 


Left: Drivers side injector on 3738, Right: Boiler Feed Injector Diagram

From left to right you have the steam cone, the combining cone and the delivery cone. The first is the steam cone and as you might expect, this is hooked up to the steam supply from the boiler. Steam goes in from the wide end of the cone and exits from the narrow end of the cone. This causes the Venturi Effect** to come into play. If you restrict a pipe, it has the effect of taking the pressure energy in the working fluid (the steam) and turning it into velocity. To the layman, it speeds up. This is why your garden hose without a nozzle on the end seems to run out in a fairly lacklustre manner but with the nozzle on the end you can squirt it clear across the garden.

This jet of steam then goes into the combining cone. As it is now going quite fast, it reduces the air pressure around it and pulls the water along for the ride. It literally sucks it into the combining cone. Whilst travelling through the combining cone, the steam and water are, er, combined. The steam therefore turns back to water. Up until now it all seems quite reasonable but all we have is a fast moving jet of water. It shouldn’t be able to do more work and overcome the energy of the steam that caused it to happen in the first place right?

Drawing of a Restarting injector from the Drawing Archive

Well, no. There is a little bit more energy that is stolen from somewhere else and it’s this that makes the difference. You were probably taught at school that there about the three states of matter. A solid, a liquid, and a gas.*** You also know that if you heat up ice it becomes water and if you heat that water high enough it becomes steam. In order to make that change between one state and another, there is a little extra energy needed and this is known as latent heat energy. As the steam turns back to water, this energy is released.

This gives our steam water combination the last kick of energy. As it goes through the delivery cone, the reverse Venturi effect happens, it slows down. Physics tells us that energy cannot be created or destroyed and it has to go somewhere. The energy is in fact returned to the water as pressure energy. This is higher than the original boiler pressure and it can overcome it and force its way past the one-way valves into the boiler.

Utter genius.

Let this sink in. A man in the middle of the 19th Century thought this thing up. In his head. Henri Giffard truly was a genius (a most overused word today) and developments such as the self restarting injector that GWR locos use and the exhaust injector (that recycles some of the energy from the exhaust steam) only made it better as time went on. It has its limitations. They don’t work well with hot water for example. In fact, No. 4079 Pendennis Castle had to be fitted with special injectors to enable it to operate safely in the Australian desert. We also always run with two operational injectors at the start of the day in case one fails. Even so, they are nothing short of brilliant.

Oh, and one more thing - they are anything up to 98% energy efficient...

Saint Catherine 2918 Pad c. 1908 - Steam coming from injector overflow

*It was Arthur C. Clarke who said “Any sufficiently advanced technology is indistinguishable from magic."

** Named after Italian genius Giovanni Battista Venturi. Amongst other things he was a physicist, diplomat, man of letters and a historian.

*** There are actually more but who’s got time for plasma or a Bose - Einstein condensate? You people have got other things to do.


The Return of the Champion - Chapter 2

Well, lots of jobs still to do on the mighty 4079 ‘Pendennis Castle’, but progress is being made. Let’s take a look in the history books before again opening the workshop doors and taking another of our exclusive peeks. So, what makes a Castle a Castle? Well, that all starts way back in the 1920s. Let’s hop in the time machine...

Star class 4014 Knight of the Bath at Old Oak Common, 25 June 1932 - photo Ken Nunn

Picture the scene. It’s 1923 and the craftsmen at Swindon are building the first batch of Castle Class Locomotives. These are essentially an enlarged Star Class loco and this is so true that the Star drawings have merely been drawn on with red pencil to show the changes! A larger cab with such luxuries as side window and a roof that has at least a hope of keeping the rain off the crew, slightly larger cylinders and a larger boiler.

The Star was an excellent machine in its own right; the four-cylinder express passenger design that was developed by the GWR was a winner from the start. It had a great deal of power for its size, was highly efficient and made a huge impression on the London & North Western Railway when an exchange trial saw one absolutely trounce them!

Star class 4005 Polar Star hauling the 10 am Euston to Glasgow Central on 20 August 1910 passing over Bushey troughs during the exchange trial with the LNWR - photo Ken Nunn

The Castle boiler was in fact, something of a compromise. Collett has intended to use the Standard 7 boiler as was fitted to the 47XX class 2-8-0 fast freight machines. This was vetoed by the civil engineering department, citing the wear and tear the extra weight would cause. So, forever pragmatic, Collett produced a slightly smaller, slightly lighter version of the boiler and with little thought to poetry, dubbed it the Standard 8. This was an absolute winner.

Postcard of Pendennis Castle when new in February 1924

Now let’s look at some of the work that's been undertaken to ensure 4079 returns to steam . . .

There were a number of jobs needed when we took on the job of bringing No. 4079 back to life, one of the biggest was the cylinder block. There were two main issues. Firstly, the valve and cylinder liners were all in a very poor condition. Replacement was really the only option. This is a big job on a Castle as it has 4 cylinders and therefore 8 valve liners. Tiresome but not in any way new ground.

Machining one of the new cylinder liners

The second job was a bit more of a concern. The cylinders on a Castle are made up of 4 sections. The two outer cylinders and valves, the inner cylinder and valve block that also has the front section of the smokebox saddle. The final section comprises of the rear of the smokebox saddle and the two exhaust pipes from the outer cylinders that lead up into the smokebox. On top of this is a 2 to 1 manifold that then concentrates the blast straight up the chimney.

The problem was that this flange where the manifold bolted was broken. The whole top half was snapped off. This was a case of good news – bad news: the cast iron welding company said they most certainly could repair it but would only guarantee the repair if they could take the part to their works. For those that don’t know, to weld cast iron you need to heat it up before doing it. Not easy if it’s attached to the frames of a locomotive...

This necessitated us taking it out. The bolts that hold it in are what is known as fitted. This means that the plain section of the shaft of the bolt is machined to a very tight tolerance to fit exactly into the hole it goes in. They do not give up their hold easily. We had to start by making a jig to get these bolts out. Which had to fit into all sorts of inaccessible places where Swindon saw fit to secrete a bolt(!). It took a day. It was hooked up to a crane and we tried to lift it but the fit was so good that it took a whole day of very careful jacking, tapping, cajoling and anything else you can think of to get the thing out.

Smokebox saddle awaiting boiler replacement. The temporary wooden cover to prevent debris falling into the valves while work is going on

It went away for repair and when it came back, in the greatest tradition of the Haynes manual, replacement is the reverse of removal so another solid day saw is slowly push it back in and a further day got all the bolts back in...

Recent efforts on the project have been really pleasing. Pete Gransden and Ali Matthews have been working solidly on the boiler to prep it for its examinations by the inspector. This really is just a whole heap of tidying up and the boiler is now watertight. Well done to them!

4079's boiler sits on the boiler wagon in Didcot's lifting shop - November 2020

The last of the serious work on the cylinder block - the grinding in of the pressure relief valves on the ends of the cylinders is now complete and they just now await the new cylinder drain cock pipes and some paint here and there to complete the front end to the top of the running plate.

Not long now...

All the best,

Drew and the 4079 Team.


The Iron Warhorse

5322 in France, 3 October 1918

As it’s early November, thoughts naturally turn to the season of remembrance. We are privileged to have a very special resident at Didcot who is quite literally a World War 1 veteran. This is none other than the sole surviving GWR Churchward Mogul No. 5322. The engine that went to war.

One of 5322's sister locomotives, 5319, on active duty in France

The Churchward Moguls started as an afterthought and became a legend. Eventually 342 were built making it the most numerous single class of GWR tender locomotive. The Mogul (the name of the engine’s 2-6-0 wheel arrangement) wasn’t on the list of standard locomotives that George Jackson Churchward was designing for the GWR at the beginning of the 20th Century. Types like the Star, Saint and 28XX 2-8-0s had all been planned for but it quickly became clear that there was a sort of ‘gap in the market’ type situation. This was for a smaller, lighter tender locomotive capable of being a go anywhere and do anything sort of machine.

This was actually a really good test for Churchward’s standardisation program. Could a whole new locomotive class to meet a whole new set of demands be built from the set of standard parts that Churchward and his engineers had developed? Well, the short answer is yes. The long answer is that, according to legend, only 11 extra drawings were required to do so. If this is true, you need to realise that some of those were general arrangements (the drawings that shows where all the bits go), so the actual number of new parts drawings would be lower.


5322 in ROD khaki livery

The 1911 prototype engine was basically a 2-6-0 tender version of the 3150 class large Prairie (2-6-2) tank engine. Although Harold Holcroft (the project’s chief draughtsman) claimed that they only noticed the massive similarity once the project was finished, it seems that Churchward was keen to point it out when selling the design to the GWR board of directors. The Moguls had a standard 200 psi No. 4 boiler, 5’ 8” driving wheels, 18 1/2” diameter cylinders and this gave them a tractive effort (pulling power) of 25,670lbs. The tender was almost always a Churchward 3,500 gallon version. As might be expected of the majority of standard GWR machines from Churchward’s stable, the Moguls became firm favourites and were maids of all work. Freight, passenger, the lot. This doesn’t however explain what our No. 5322 has to do with World War 1...

In 1917, the call went out to the railway companies of the U.K. to supply some more locomotives to serve behind the lines of the Western Front in order to keep the men and war materiel flowing. The railways were to supply a total of 160 machines and they were all to be of the 8 coupled variety. They should all have 8 small driving wheels which was pretty much standard for British 20th Century heavy freight machines. The problem as far as the GWR was concerned was that all of the 2-8-0 type locos they had and could build were desperately needed for coal traffic. Don’t forget that the Royal Navy was powered by coal at this point and the threat of the German U-Boat submarine fleet was potentially devastating to supplies for both the war and the U.K. itself. The GWR therefore decided to send the mighty Moguls instead. Its General Manager, Mr Frank Potter, explained that: “The Great Western type of 2-6-0 engines is in point of power and efficiency practically equal to other Companies 0-8-0 engines”. Quite the claim - but amazingly true. The government were eventually convinced to release the materials to build 20 new Moguls. Technically therefore these machines were built for the Railway Operating Division (R.O.D. - the railway section of the British Army at the time) and not the GWR although the company officially recorded them as being ‘on loan’. They were turned out at a rate of 5 per month and of the 20, 11 were conscripted into R.O.D. service. For the record, they are Nos. 5319 to 5330 but for some reason not No. 5327. Perhaps it had a problem on completion that could not be quickly fixed and therefore No. 5330 was substituted instead?

5322 in ROD black livery with period re-enactors at a special World War I commemorative event

The engines received the R.O.D. livery where the tender was emblazoned with the letters R.O.D. And then the loco number. The colour is not confirmed. The official colour for R.O.D. Engines was black but a number of references in the GWR paperwork denoted that these machines were painted in khaki. No. 5322 has appeared in both versions in preservation as a result! They also had a modification that our Mogul still carries to this day. If you take a look at where the cab sides meet the cab roof, you will see two hooks. A portion of the rear strengthening rib in this area has also been crudely chiseled away. This is on both sides and the mystery as to what these were for was solved when a deactivated short magazine Lee Enfield .303 rifle - the standard weapon of the British Army at the time - was found to easily clip into place. One for the driver, one for the fireman. It’s the only steam engine that we have with integral gun racks...

The mystery of the extra hooks revealed with a decommissioned Lee Enfield rifle

These locos were sent to the Western Front from Portsmouth Harbour in two trips, one on the 20th August and the second on the 21 September 1917. They were immediately pressed into service in the North of France. They worked army supply trains generally from Calais to the railheads around Hazebrouck. They were worked hard but rose to the challenge, gaining an excellent reputation with the R.O.D. crews. It can’t have hurt to have these relatively small, efficient, powerful locos that were capable of a reasonable turn of speed when required. There is a fantastic recollection of Mr C. E. R. Sherrington (then an officer in the R.O.D.) who saw No. 5322 in France in 1918 here.

The locos served in France until 1919 and are recorded as being returned to Swindon in March and April of that year. Amazingly, given the intensity and horror of that conflict, they all made of back to Blighty but not unscathed. It is said that at least No. 5325 came back with war wounds, receiving bullet holes after coming under enemy fire. The engines were all back in service by the beginning of June and went on to have regular careers on the railway. The last of these old soldiers to succumb to the march of the diesels was our very own No. 5322 when she was withdrawn on 24 April 1964. She was sent to Barry Scrapyard in South Wales from where she was rescued but that’s a tale for another time.

We are obviously very proud to look after such an important piece of history as No. 5322. The human veterans of this conflict are now all gone and it is down to the objects, places and the documents to remind us of what happened. Our ‘old soldier’ stands as our memorial to WWI. It is sad to think that World War Two is also fast leaving living memory and soon the last of that generation’s voices will fall silent too. It is so important for us to keep telling the stories. To remind ourselves and subsequent generations of the huge sacrifices and heroism that are the foundations of the freedoms we enjoy today. This is our duty as the custodians of this small part of WWI history. A very minor burden when you consider what has been and continues to be sacrificed by the brave men and women of our armed forces and their families...

“They grow not old as we that are left grow old. Age shall not weary them, nor the years condemn. At the going down of the sun, and in the morning, we will remember them.”


P.S. While we are usually asking for donations for our projects, it is only appropriate that with today’s blog, we highlight the many organisations that look after our forces veterans and their families. If you can, please make a small donation to one of the many organisations taking care of them after they have done so much to take care of us.

The Royal British Legion

Help for Heroes

SSAFA - The Armed Forces Charity

5322 complete with wreath of poppies on Remembrance Day - 9  Nov 2008


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