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Going Loco - June 2021


The Lampyridae* Legend

Well, haven't I been lucky? First I get to sit back and let you read Phil Morrell's write up on No. 1466's restoration (another update soon by the way!) but I contacted Sam Bee, who was one of the leading lights of the building of our replica broad gauge engine Firefly and he has come up trumps! So, without further ado, let's find out about the return to existence of a really historically important machine. Play it again Sam!

Firefly in action on Didcot's broad gauge demonstration line

The Firefly Project was the brainchild of John Mosse E.C.Eng. M.I.Mech.E., R.I.B.A. who had served in the Royal Navy for 20 years, his last ship was HMS BELFAST between 1950-1957 in the rank of Lieutenant Commander, as senior engineer aboard. On leaving the navy he retrained as an architect, living near Bath. One of his commissions was the renovation of the original Bristol terminus of the G.W.R. to the state we see today. One day he was standing all alone in that wonderful train shed when it occurred to him that one of the original locomotives would complete the scene.

John spoke to the manager Western Region, based at Bristol, who dispatched him to a meeting at Paddington. There, the person he was introduced to was Tom Richardson, who had dug out original drawings of the Fire Fly Class and expressed enthusiasm for joining the project. This was in 1984. Others were persuaded to give their support, including S.A.S.Smith sometime Locomotive Works Manager Swindon, and Sir Peter Parker. The Firefly Trust was formed to collect funds so that after some 5 years enough was in hand to make a start on construction; the committee included Tom Richardson, as above, Ken Gibbs and Alan Wild, both ex-Swindon men, Ken being a senior fitter and Alan a drawing office man.

Sam Bee, left, discussing paperwork with Major John Poyntz from the Railway Inspectorate during Firefly's official test - March 2005

Now John was familiar with steam, but driving big naval turbines, his knowledge of railway locomotives being rather limited he had done well to assemble the above team. After some heated discussion on specifications, drawings for the actual build were produced. A shed on the water front in Bristol was leased, labour arranged thanks to a Government youth training scheme, thus allowing the locomotive frames to be ordered and duly erected. Then disaster stuck within one week, the training scheme was withdrawn and the shed condemned as unsafe, reported subsidence meaning it was liable to fall into the harbour (it was still there many years later!). Help was at hand with an offer of space in the Works at Didcot. That is where the writer first saw the frames and wheels sets during a passing visit to DRC in 1990. With a great interest in early railway history I became hooked and joined the working team, then a little later invited onto the managing committee too.

Champagne launch for Firefly, April 2005

Famous Railway Artist Terence Cuneo came to name the locomotive at Didcot. He produced a painting emerging from Box tunnel and kindly handed the copyright to the Firefly Trust to enable the raising of funds; the original is now with John's son.

The NRM’s replica 3rd class broad gauge coach being rebuilt at Didcot, March 2005

To put the Fire Fly class locomotives in perspective, they were the Castle class of the 1840s, if you will, fast and reliable, all 62 of the class. We had ‘63’ chalked on the frames of the latest member of the class! The first class designed by Daniel Gooch and delivered between March 1840 and December 1842, they were a development of the Star class, 12 of which had been ordered from Robert Stephenson, Newcastle-upon-Tyne, as a stop-gap. It is probably little known today that 21 similar engines with smaller wheels were introduced at the same time to cope with the steeper gradients west of Swindon, the Sun class. Thus it is an iconic design which enabled the G.W.R. to establish itself with some panache and thrash the Narrow Gauge faction at the subsequent gauge trials, which I trust explains why we built it, she is of historic importance. But of course the BG track at Didcot needing something to run upon it was an added incentive.

John was rather authoritarian, which put some people off joining the team. That changed, the workforce expanded, with about 10 of us from various walks of life but most with engineering expertise. We had great support from the GWS, with free run of the workshop and machine shop, as well as occupation of our corner of the workshop, in exchange for an agreement to operate the completed locomotive at DRC.

Victorian costumes in abundance on Brunel's 200th birthday, 9 April 2006

It was necessary to make modifications to ensure compliance with the modern construction standards of that time. The original design was remarkable and we kept to it as much as possible, doing our best to hide the modifications from public view or make them unobtrusive. This included a frame cross member just ahead of the firebox to which the inside bar frames are attached, instead of directly to the firebox at rear and cylinder block at front. We added a blower, ash-pan damper and modern type cylinder cocks. Braking was described by Brunel as “tolerably useless”, not good at 60 mph with 100 tons behind; it consisted of wooden brake-blocks on one side of the tender only, later changed to cast iron, operated by the handbrake, and the reason for the invention of the second ‘brake’ whistle to alert the brakesmen in the carriages to apply their handbrakes.

Sam Bee and Kevin Dare, 13 April 2009. In the early days of railways the footplate crews wore white uniforms

We obtained authority from HM Railway Inspectorate to keep to that layout provided vacuum braking was applied to the tender brakes and piped to the carriages. So Fire Fly itself has no brakes! Gauges for vacuum pressure and boiler pressure are unobtrusively mounted within the back of the haycock cover, the boiler does not have the original haycock, being of standard round top design, built by Israel Newton, boilersmiths. The regulator valve is mounted in the small dome, present on some but not all original Fire Fly boilers as the regulator was in the haycock. Water feed is by GWR pattern injectors in place of the mechanical force pumps of the original. Finally, the safety valves are modern, the main one at rear is a single valve of standard Swindon design in substitute for the original Salter valve, which is no longer allowed on a new design of boiler, as also the lock-out type valve at the front of the boiler barrel, which we replaced with a Ross-Pop valve of suitable size and able to be accommodated within the original design of brass housing.

Firefly in action at Didcot alongside the second new build replica of a mainline locomotive, 60163 "Tornado" during the latter's visit to the Centre in 2009

Much help and guidance was provided by paid staff and locomotive department volunteers, not least Mick Dean. And it was Mick and myself who sallied forth early in 2005 on the test runs with Major John Poyntz, all proving to be well.

Meanwhile the NRM had been persuaded to transfer their two BG carriages to Didcot. They were constructed in 1986 for Iron Duke to pull and have vacuum brakes. They were overhauled in the C&W works ready for operation. The track too had been fettled. Thus we were ready for operation in spring 2005 and had a grand gala opening, with the good and the great present.

To our delight the Heritage Railway Association awarded the project their annual John Coiley award.

The NRM's replica Iron Duke alongside Firefly on the broad gauge lines at Didcot

We then operated throughout each summer until the boiler ticket expired in 2015. During that time we acted as a unit of the locomotive department. I was tested on my ability to wash out a boiler, as learnt over my years at the Bluebell Railway and subsequently carried out all the washouts and preparation for the annual visit of the boiler inspector, carrying out maintenance too but calling on the Works staff as needed. After Iron Duke arrived from the NRM we coupled on Fire Fly to shunt it into the train shed. The first time two Broad Gauge locomotives had moved coupled together since the 19th century. And you all missed it! A most enjoyable 10 years. Subsequently we handed the locomotive over into the care of Great Western Preservations for safe keeping.

And there you have it folks - a truly massive achievement condensed down to a few paragraphs. We'd all love to see the broad gauge operating again. Both the track and the rolling stock need work to make that happen but it's not beyond the realm of possibility. We really need to get our 50 ton breakdown crane sorted first as this will make Firefly's overhaul so much easier. Until then, come and marvel at the determination and grit of the original G.W.R. of the 1840s and of the Firefly Trust who have done so much to bring history back to life for future generations.

*The Lampyridae are a family of insects, of the order Coleoptera, commonly called fireflies due to their use of bioluminescence during twilight.


Yorkshire Gold in a Didcot Mirror

No 29 in action on the North Yorkshire Moors Railway - photo courtesy of Philip Benham

We are sometimes lucky to get interesting locos visiting Didcot Railway Centre. There have been a myriad of different machines over the years. The first was No. 4079 Pendennis Castle when the society held its first open day at Taplow in 1965. She was made a permanent part of our collection in 2000 and thus she no longer counts as a visitor! This year we are lucky enough to have a very unusual visitor in the shape of the lovely ‘Lambton Tank’ No. 29 from our friends at the North Yorkshire Moors Railway (N.Y.M.R.). The ‘Lambton Tank’ has a number of facts about her that we can match with locos in our collection so let's hold up the Didcot mirror and see what reflects back!

The ‘Lambton Tank’ (more accurately named either Lambton Colliery Railway No. 29 or Lambton, Hetton & Joicey Collieries No.29 - after some mergers in 1910) is named after its original home, the Lambton Colliery* in County Durham. Coal had been extracted from the area as far back as the 1600s. It became a big industry by the 1780s and was an early adopter of railway type technology. As far back as the 1730s, horse drawn tramways were used to move coal. In 1819, a private tramway was purchased and added to the system. This provided a link between their system and a line that once ran between Bournmoor and Philadelphia. This got them access to the River Wear which in turn got them access to the Port of Sunderland.

Although it began using steam locomotives in 1814, some sections of the route were too steep for the early engines and so the wagons had to be hauled up and down them by stationary steam engines that used a rope and a massive winch. By the 1860s there were over 70 miles of track in the system. Running rights for trains to pass over it hauled by engines of the North Eastern Railway were now in place and this secured the transport of Lambton coal to the rest of the world. By the 1880s steam locomotives were used throughout, the rope worked inclines being removed.

Didcot Mirror #1 - Working in a Colliery.

Several of our engines have links to working in a colliery and coal traffic but two have history close to the industrial life of No. 29. No. 1340 Trojan who worked at the Netherseal colliery at Burton-on-Trent, Derbyshire during WWII. See my blog post Return of the Little Warrior (16/04/21) Pannier Tank No. 3650 also saw out its final operational years with Stephenson Clarke Limited who were a private colliery operator at Gwaun-cae-Gurwen in South Wales. The first ever Going Loco blog from (27/3/20) features this very subject!

3650 in the ownership of Stephenson Clarke PD fuels Ltd at Gwaun-Cae-Gurwen open cast pit - from a slide by R.Monk, 21 April 1966

The older and smaller 0-6-0 locomotives on the line were beginning to struggle with the increasingly heavy loads on the railway by 1900. As a result, a programme of modernisation of the fleet began. They turned to Kitson & Co. of Leeds, West Yorkshire. They specified an engine type that was synonymous with the coal industry. The 0-6-2 wheel arrangement was used extensively in the Welsh Valleys, and by the London, North Western Railway on their appropriately named ‘Coal Tank’.

Lambton No 29 with a demonstration goods train on the NYMR - Photo courtesy of Ray Brown

Didcot Mirror #2 Built By Kitson & Co.

The Kitson company that built No. 29 in 1904 also built No. 1338 in 1898. See my Cardiff Connection Blog (14/05/21) on this engine for details.

At just under 60 tons, this engine was quite a beast! A 165 psi boiler, two inside 19 inch diameter x 26 inch stroke cylinders, slide valves operated by Allen straight link gear and 4 foot 6 inch driving wheels made for a potent package. It had a Tractive effort** of 23,500 lbf. To give that context, that's about the same power output as No. 2999 Lady of Legend! Ok, she won't go as fast as No. 2999 but this engine didn't need to!

Didcot Mirror #3 Tractive effort

No. 29 has almost the same Tractive effort as No. 2999 Lady of Legend. Is that cheating? It is a bit I suppose! How about this one then:

Didcot Mirror #4 Allen Straight Link Valve Gear.

This method of operating the valves on a steam locomotive wasn't common in the U.K. but, just like No. 29, No. 1363 has this same system. I have written about No. 1363 twice. The Big 13 - Lucky For Some? (24/04/20) and 1363 - Survivor Extraordinaire (12/06/20).

The new loco was No. 4263 in Kitson's order book but it was numbered No. 29 when it arrived at the Lambton Railway. The railway ended up with a few 0-6-2s that were very similar to No. 29 from various sources including Robert Stephenson & Co. and some ex. Taff Vale / Great Western machines as well. It spent the majority of its working life operating trains between the pit heads near Philadelphia and the coal staithes at the Sunderland end of the line.

Didcot Mirror #5 The 0-6-2 Wheel Arrangement

The 0-6-2 wheel arrangement was a Welsh favourite. It was so common on the railways that when the GWR absorbed railways in the area, they designed and built their own! Our example is 56XX Class No. 6697 of 1928.

No. 29 continued in service until almost the end of the County Durham coal field. The coal industry was nationalised in 1947 and the National Coal Board commenced closures of sections of the system in the early 1950s. With the end of the local coal industry in the late 1960s, the writing was on the wall for No. 29. In a move typical of the nationalised industries of the time, she returned to traffic from a full overhaul in October 1968 and was withdrawn from service and placed in store at Philadelphia on the 15th February 1969. Tax payer's money at work...

Didcot Mirror #6 The ‘Unwanted’ Class 14

This almost wanton consumption of money wasn't restricted to the National Coal Board. British Rail ordered a whole heap of brand new diesel locomotives off the drawing board which either didn't work or were designed for a task that no longer existed. Our Class 14 No. D9516 was built as one of 56 of its class in 1964. They were all withdrawn by 1968...

Fortunately, No. 29 came to the attention of some volunteers from the N.Y.M.R. Along with No. 5 (one of the Robert Stephenson & Co. 0-6-2s of 1909), the ‘Lambton Tank’ was purchased and made its way to the nascent N.Y.M.R. It has been in service with them on and off ever since. The biggest challenge she faced was in October 2014 when cracks were discovered in her cylinder block. This needed complete replacement but this redoubtable survivor was repaired and was running again by 2019. We are now lucky to give her a holiday and the full ‘Didcot Experience’. So, if you'd like a new perspective on this fascinating machine, come and see her operating up close. She will be with us until the August Bank Holiday - to see when she's due to run, check our Locomotive Roster.

Didcot Mirror #7 Robert Stephenson & Co.

Ok, at bit of a stretch but hear me out! No. 29s ‘sister’***, No. 5 was built in 1909 by Stephensons. This company merged in 1937 to become Robert Stephenson & Hawthorns. In 1944 they became part of English Electric. In its various forms, this company and its parent built No. 1 Bonnie Prince Charlie in 1949 AND the traction motors fitted to Class 08 No. 08 604 Phantom.

Crikey - all this linking stuff together is hard work! Thanks to Harry Pettit and Graham Hukins for top suggestions! There has been a fair bit of mental gymnastics going in here to make this work... It's addictive though. I think I realise why these silly conspiracy theories get started. Now, if I can just link Alpha Centauri, the lifting shop at Didcot and my sandwiches from last Saturday, I think I can prove they were abducted by aliens. I won't be a minute...

*Named after the nearby Lambton Castle. The Lambton Family that lived there were a major part of the organisation.

**A measure of an engines pulling power. See my blog ‘Working This Out is a Real (Tractive) Effort’ (12/02/21) for a full explanation.

***Possibly more of a close cousin or perhaps a ‘sister from another mother’ as they share a very similar design but weren't built by the same company?


Luxurious Saloons? Super!

The Great Western Magazine of January 1932 included this photo showing the interior of one of the Trollope saloons

The G.W.R. always saw itself as something special. It had a way of doing things that set it apart in many ways from its contemporary railway companies. They always tried to make it look that way too. They often catered to people of considerable means or, to put it another way, the completely rich! We have a few vehicles that come under this remit in the collection at Didcot. In the first of an irregular, occasional and when your blogger remembers(!) series on the luxury passenger vehicles in the fleet, we will today take a look at the Super Saloons.

The short-lived Torquay Pullman hauled by a Castle class locomotive. Photograph - A L P Reavil

Taking people to and from ships was a staple of the G.W.R.'s business from day one. In fact, allied with Brunel's great ships, the idea was to offer a complete travel service from London to New York. An idea too far ahead of its time but you can't fault the ambition and foresight...

Post WWI, with the emergent nouveau-riche of the period, this dream sort of came to its zenith. Although the original intention had been to offer this type of service from London to Bristol*, Plymouth became the focus of the traffic. In doing so, there was always the desire to cater to the first class passengers off the ships. The master of luxury travel in the U.K. at the time was the American Pullman company and this is where the majority of the railways went for their most luxurious trains. It was run on a sort of ‘franchise’ basis. Pullman supplied their own cars** and staff and these were used by the various railway companies. The G.W.R., being the G.W.R. however, wasn't convinced. They had always had high standards of vehicles in first class and considered that their level of luxury was luxury enough.

No 9111 King George on display at Paddington when new

This notwithstanding, the G.W.R. still gave Pullman a chance to prove themselves. A seven coach set was leased in 1929 but it wasn't successful and the lease was terminated in 1931. There are many reasons why this didn't work - the biggest of which was of course the Great Depression. Despite the economic downturn, Chief Mechanical Engineer Charles Benjamin Collett tasked the coach designers at Swindon with having a go at building a better Pullman coach. As a result of the G.W.R.'s broad gauge history, their vehicles could be built wider than the vehicles of any the other U.K. railways. The plan that was drawn up was 61 feet 4.5 inches (18.707 m) long and 9 feet 7 inches (2.92 m) wide. In order to assist in going round curved track, the end doors were placed on short sections at each corner that were angled inwards at 30 degrees from the coach sides and the ends were of a bow shaped design. This did limit their sphere of operations but as they were only ever intended to run on the G.W.R.'s main routes, that wasn't an issue.

There were only 8 of these vehicles built which were completed by 1932 under lot No. 1471 to diagrams G.60 & G.61. They were all named after members of the royal family thusly: No. 9111 King George, No. 9112 Queen Mary, No. 9113 Prince of Wales, No. 9114 Duke of York, No. 9115 Duke of Gloucester, No. 9116 Duchess of York, No. 9117 Princess Royal and No. 9118 Princess Elizabeth. The thing that made them luxurious of course was their interiors. The first two were built under diagram G.60 and this denoted that their interiors were designed and built by the prestigious furniture makers Trollope & Co. These two have beautiful French-polished light-coloured walnut, with book-matched burr veneer panels on the interior sliding doors. The ceilings are also a thing of great craftsmanship, looking like it's been borrowed from a stately home! The problem with this sort of work is that it is REALLY expensive and the craftsmen at Swindon known as the ‘Saloon Gang’ were tasked with fitting out the other 6 under diagram G.61. These coaches featured French polished dark English walnut, with gold-leaf hairlines outlining the panelling. In all the coaches the seating is amazing. They comprise fold down tables that connect to the coach walls and plush, free standing wing-back chairs. These were arranged with an average of 26 in the main saloons and 4 in the private Coupé. There was a toilet fitted at each end of the coach.

One of the saloons converted with a kitchen, 9117 or 9118, being stocked with refreshments at Paddington station in the early 1960s

In 1937 the coupé and one lavatory were removed and a small kitchen fitted in their place in Nos. 9117 & 9118. This was due to the fact that a non - super saloon kitchen vehicle had to be used in the super saloon trains which kind of wasn't the point! The kitchen preserved in No. 9118 is amazingly still completely intact and as it was when fitted. The only type of coach that wasn't built was a brake coach with a guard's compartment. These were usually provided by a pair of full brake^ vehicles. Due to their higher than normal weight, they were used more often as either as one or two added to a train of regular vehicles or as an exclusive train of 3 saloons and two or three full brakes for the passenger's luggage. To travel on the Super Saloons, you had to buy a full first class fare and then pay a 10 shilling supplement. To put that in a modern context, a first class fare from Paddington to Plymouth today is £194.00. 10 shillings from 1935 in 2021 is worth about £25. So our hypothetical modern Super Saloon fare is £219 for a one way ticket. The average 1935 wage in modern money is very roughly the equivalent of £500 per month...

Three of the saloons on the back of a Newbury Races special, photographed at Langley in 1962 by Mike Peart

The move of the boat traffic from Plymouth to Southampton lightened their workload so, as well as the Ocean Liner Express duties, they became regulars on dining trains to Newbury Races and as private hire vehicles. They were always kept at the bottom end of the Carriage Shed at Old Oak Common. This was close to the offices (and therefore the eyes) of the coach inspector who ensured that they were maintained in immaculate condition ready for special journeys at a moment's notice. This is how they saw out their service. They lost their names when repainted into the British Rail Crimson and Cream livery in the early 1950s and they were eventually withdrawn in the B.R. version of the G.W.R.'s. Chocolate & Cream livery in the early 1960s with the last Super Saloon Ocean Express being run in September 1962.

A special journey for two of the saloons with Great Western Society members boarding them at Reading to travel to the AGM at Bristol in 1966. BR arranged for the saloons to be coupled to the rear of the 9.45 am from Paddington to Bristol for members to ‘road test’ them and decide whether they were to their liking for preservation. The fare charged each member was a 2nd class day return

Out of the total of 8 saloons built, remarkably 5 have survived. Nos. 9111 & 9116 are restored and in service with our friends on the South Devon Railway. We have Nos. 9112, 9113 & 9118. Our trio is the subject of a very long term restoration project. Reaching Didcot in 1976, by the end of the 1980s time had started to catch up with them and they were all out of service with us by the early 21st Century. The restoration of No. 9113 is a fair way along. As a ‘standard’ (!) super saloon, this one was chosen to be done first. Next on the list will be No. 9118 and its kitchen, leaving that exciting and very complex interior on No. 9112 as the final serving. It represents quite a challenge! It is hoped that in the not too distant future, visitors to Didcot will be able to marvel at the incredible craftsmanship^^ and period design of No. 9113 Prince of Wales and get just a small taste of what life for the 1930s equivalent of today's ‘one percenters’ was like.

The Great Western Society’s Vintage Train at Paddington with saloons 9118 and 9112 in the mid 1970s

Pretty cushy if those chairs are anything to go by...

Jessica Raine and David Walliams filming Partners in Crime in No 9112 at Didcot in 2015. The scene was set in Paris, hence the SNCF antimacassars on the seats

 *This is where a goodly proportion of the money to build the G.W.R. in the first place came from.

**The Americans use the word ‘Car’ to describe the vehicles pulled by locomotives on the railway. Passenger Cars = Coaches and Freight Cars = Wagons in the U.K.***

***The fact that one of the initial investors in the London Underground was an American means that on their trains, the passenger vehicles are called cars and not coaches. I don't know if that's relevant or even interesting, but it is true...

****Yes - the Paignton from the Paignton and Dartmouth Railway! A.K.A. Where blue kings like to go on a summer holiday.

^A passenger coach shape on the outside but with luggage / parcels / newspaper / other similar stuff storage spaces instead of seats and a guard's compartment inside.

^^Not forgetting of course the incredible restoration talents of our Carriage & Wagon department. They create exquisite art with timber while the loco department use wood to light fires...


There is a large part of our restoration of rail vehicles - be they locomotive or carriage and wagon - often overlooked but it is obvious when you think about it. The wheels. They are literally and figuratively the foundation of every restoration. There is however a lot to a wheel. Let's roll out...*

We'll start with a bit of anatomy. Every rail vehicle will have at least two wheel sets. This will comprise of an axle with a wheel on each end. There are the hubs in the middle then the wheel centres. The tyre is on the outside and in most cases in the steam age, these were replaceable. Strange but true! We’ll talk more about that later.

A restored Mansell wheel under coach 290 at Didcot

The wheels themselves are a work of engineering art. There are many types of wheel. The simplest being a disc. Most coach wheels in the collection are of these type. There are outliers here in that there are also the beautiful Mansell wheels. These have steel centres and rims but a hardwood section** in between. The idea being to use it as a damper to reduce noise - particularly in 4 and 6 wheel coaches. These had a far more rigid connection between the wheels and suspension and the body of the vehicle than a more modern vehicle where the wheels are on separate little trucks called bogies. Anything you can do to reduce the vibration and noise is a good thing. There are other oddities such as the Bulleid Firth Brown, which have a number of cut outs to reduce their weight. These are synonymous with the Bulleid Pacifics and the Q1 Austerity 0-6-0s of the Southern Railway.

Duke class No 3253 Pendennis Castle, sporting Mansell wheels on the bogie and tender

The other main type is the spoked wheel and this is the type we see on the majority of U.K. steam locomotives. The idea is obviously older than the railways as it was seen on horse drawn vehicles for centuries beforehand. The process for making them was fascinating and through a remarkable set of images we can show you how they were made. The photographer was a guy called Walter Nurnburg. He was born in 1907 and after art school in Berlin, he moved to London in 1933. Although declared an enemy alien in 1939 - having all his cameras confiscated in the process - he ended up joining the British army in 1940 and was invalided out on medical grounds in 1944. His style of photography lent itself to industrial subjects and he found a living in this area post WWII. He became fully British in 1947 and at his death in 1991, he had also been a teacher of photography in the Guildford School and the Polytechnic of Central London and received an O.B.E. for his life's work.;

In January 1948 he visited the newly nationalised Swindon Locomotive Works. This album of photos was discovered by our provider of photographs, Frank Dumbleton. He told me that:

“There was an album of his photos in the publicity office at Paddington and one day when I was in there I was given the album, otherwise it would have gone in the bin


In doing so, he preserved some absolute gems. We even have the names of the guys working too!*** The first image shows pattern maker Mr. A. A. Taylor constructing a wooden pattern for a large driving wheel. This is where all large metal castings start. The wooden pattern is made to a very high level of precision and is in fact a small amount larger than the finished item. This is to take account of shrinkage. When metal is heated, it expands and if it is heated to the point of becoming a liquid, it’s done a fair bit of expanding. As a result, the measuring instruments in the pattern shop were scaled. A separate set for making things in brass, cast iron, steel. Different metals expand different amounts. A mould made of special casting sand is made around the pattern and the pattern is lifted out leaving the negative space to be filled by the molten metal.

Once the wheel was cast and machined, the axle would have been pressed into place. This involved a press with a huge amount of force behind it as the fit is incredibly tight. A large square key way was cut into a section of the circumstance where the wheel and axle meet and a square ‘key’ was driven in to prevent it turning. This was done with a really serious two man air hammer and we have one in the works at Didcot. We call it Mjollnir...

The next job would be to fit the tyres. Unlike your Goodyear or Dunlop products, the local garage can’t put theirs on - it needs heat and lots of it. A special circular forge with burners all the way round was employed to expand the steel tyre to a point where the wheel casting will drop into it. It then cools and as it does it contracts, gripping the wheel. The above picture shows shrinkers Mr. J. Barnard, Mr. H. Phillips and Mr. H. Barkham, fitting the Gibson ring to a wheel after shrinking on the tyre. The Gibson Ring being the locking ring for the inside of the wheel. Once the tyre was worn, it would be thick enough to be put back into the lathe and turned again to restore the flange - important as it keeps the vehicle in the track! When the tyre got too small, it was cut off and a new one fitted. There were two profiles of flange. The thick one was the standard and used on most wheel sets. There was a thin profile too and this was used where a long wheelbase might cause wear round tighter corners. An example is the middle driving wheels of the G.W.R. 4-6-0s.

Here we see a rather unimpressed fitter Mr. B. Morkott, building a Castle class crank axle. He just wants to get rid of Walter and get on with his job by the look of him! He is using the super strong press to push together the components for the inside crank on an axle. If you have cylinders between the frames, as many G.W.R. classes did, the piston transmits its drive through this crank. The bits sticking up are to prevent him pushing the bits too close together and the big section he has his hand on is the counterweight for the mass of the connecting rod. The stub axle sticking up will eventually get a wheel on it.

Here we see fitter, Mr. A. E. Kirk, balancing a wheel. The wheels can be many tons in weight - a front crank axle driving wheel set for a Castle is about 5 tons. All that rotating mass needs to be well balanced. If it wasn’t, the vibrations could do serious damage to the locomotive. The machine that Mr. Kirk is using is the one used to measure the vibrations and to tell the fitters where to add balance weight. This is the same job as is done with a car tyre only a lot bigger. And yes, that is an unguarded loco driving wheel spinning at high speed within 2 feet of his left ear...

Mr. F. Austin, also a fitter, is melting lead into a wheel balance weight. If you think about the way a loco driving wheel works, there are a lot of forces acting upon it. The weight of the wheel isn’t the whole story. If you have a connecting or coupling rod connected to it, this too creates an imbalance. This is why there are the large balance weights on the driving wheels of steam locomotives. There are often different size weights depending upon what parts are connected to them. A smaller weight usually means that it’s just a coupling rod. A larger weight could mean that it will have connecting and coupling rods on them. The bigger the offset masses are, the bigger the counterbalance needs to be.

So there we are - wheels. A seemingly simple thing with many facets to their construction, operation and maintenance. Today we employ even more technology in the use of ultrasonic and magnetic particle testing to look for cracks in wheels and axles. Back in the day this was done with a hammer and a good ear. Tap the wheel and it rings true, no cracks. If you get a dull ‘thunk’ type noise, the vibrations of the hammer blow don’t travel round the wheel easily and get filled as they can’t make it over the crack. Time has moved on but the techniques used to make these wheels remains the same. No. 2999 Lady of Legend, No. 1014 County of Glamorgan and No. 6023 King Edward II all have at least one set of new wheels under them. All made in the traditional way, checked with modern techniques and enjoyed by as all just the same as the originals!

The original rear driving wheels of 6023 King Edward II were cut after a derailment at Woodham Brothers Scrapyard at Barry necessitating the casting of a new pair as part of the locomotive's restoration

6023 complete with new wheels recreates a timeless scene in the Engine Shed at Didcot

*With apologies for the pun and to Optimus Prime for borrowing his catchphrase.

**Usually Teak. Due to the hardy nature of the wood, the segments were often reused as flooring after use in wheels.

***I wonder if any of our readers have relatives in these pictures? It would be amazing to find some!


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