Edward Adams's 2½" Gauge 'Monstrous'


Today I collected the locomotive that I've been offered on loan. It's 'Monstrous', built by Edward Adams and based on the New Zealand Railways K class 4-8-4 tender locomotives built in 1932. As the full size locomotives were 3' 6" gauge it produces a very large loco in 2½" gauge!

Edward Adams was a prolific 2½" gauge locomotive builder in the 1930s and 40s and mentioned by LBSC several times in his articles in Model Engineer. Edward also wrote his own articles for Model Engineer, some in conjunction with his son Michael, who I met at the N25GA 40th anniversary rally at Cheltenham earlier this year.

Monstrous was described by LBSC in an article in Model Engineer for 3rd June 1948. According to that, Edward produced a set of drawings in May 1937 but the loco was not completed until March 1948. The chassis was completed before 1940 but the war years halted progress after that. The original K class had only two cylinders but Edward added a third with the valve driven by Gresley 2 to 1 conjugated valve gear. All three cylinders are a massive 1.5 inch bore by 1.75" stroke, as big as most 5 inch gauge loco cylinders! All four driving axles run in ball bearing axleboxes and the connecting rods also have ball bearing big ends. To feed such large cylinders needs a large boiler. The barrel is 4.125" in diameter and the grate is 6.25" long and 4.25" wide. The boiler also has a combustion chamber fitted with water tubes.

The present boiler was the third attempt at building one. The first, built by Edward, failed under the pressure test due to the crownstays not being soldered to the wrapper properly. The second, put out to a commercial firm, was ruined by leaving it in the pickle bath too long! The third attempt was again by Edward himself and this one was a success.

The loco is 3' - 1.5" long and the tender 1' - 6.5" long.

With 60lb boiler pressure the loco has a drawbar pull of 15lb (*) and was said to haul the owner with just 10lbs on the clock. According to a label in the wooden box for the tender, at the first run on 7th March 1948, the loco pulled twelve passengers with just 30lb on the clock!

* I presume this drawbar pull is based on the weight of the loco as the theoretical drawbar pull is around 86lbs. I would say 15lbs is a bit on the low side. I would expect more like 20lbs as the loco must weigh around 80lbs.*

The present owner bought the loco at an auction some time ago. He was looking for other items but the ones he wanted were going for far too much money. This loco came up and no-one seemed to know what it was and consequently it sold for relatively little money.

I will get some more detailed photographs later when I've found somewhere to put the loco out in the open but here's a few I took today at Nantwich:







I don't know if the 'Remote Electric Control' is still fitted - haven't had a good look yet but can't see any signs of it in the photos I took today. Edward and Michael wrote an article on 'REC' in Model Engineer so I must look it up.

Also at Nantwich today was Brian, a fellow member of the N25GA who is rebuilding another of Edward's locos, 'Michael', named after his son. This is based on the LBSC/ Josslin 'Uranus'. It suffered damage in an air raid during the war and the boiler had to be repaired by soldering a ring around the barrel. The boiler has now failed the necessary boiler tests so Brian is busy building a new one for it.


Monstrous and Michael


You can see the repair on the old boiler in front of the chassis.

Brian and I have been issued with a challenge - to have both locos running and double heading this time next year!


Brian had taken 'Michael' to the 40th anniversary rally at Cheltenham and also a third loco built by Edward Adams - His 4-8-8-4 Union Pacific Big Boy, still owned by Michael Adams. Now that's a loco!






Unfortunately, it seems that this loco is destined to become just a static exhibit which always pains me. Locos like this should be kept running for people to enjoy!

Another Edward Adams loco appeared on Ebay, last year I think, for sale by a German dealer. This was his 'Leadbetter', based on LBSC's 4-12-2 Caterpillar design. I can't remember whether it sold or not as the dealer was asking a lot of money for it.

There is a photo that appears in an early Model Engineer (haven't found the article yet) that shows six of the Adams stable of locomotives on his circular track. The other two are 'Puffing Billy' and 'Nobby'. The whereabouts of these two is unknown. Brian tells me that Michael Adams also has another of his fathers locomotives called Kaliban(?)


Back to Monstrous. At some point Edward tried experimenting with ways to improve adhesion of these 2½" gauge locos and one of the experiments was with double flanged driving wheels. Instead of just the normal inside flange he made wheels with an outside flange as well so both flanges gripped the rail, in other words the tread was vee shaped. Obviously, the wheel had to be machined to suit the particular rail used and was only suitable for this particular rail. I believe Edward only ran these experimental locos on his own circular track at his home so the wheels were machined to suit that (Leadbetter, mentioned above, has two sets of these modified wheels)

Monstrous has one set of these double flanged driving wheels - the trailing set. It's difficult to tell from the photographs in the LBSC article whether these 'special' wheels were fitted from the very beginning or added later.

I'll get a better photo later but you can just see the different tread on the rear set of drivers in this photo:



To run on normal rails this set of modified wheels will have to be replaced with normal single flanged ones. I would like to find some replacement wheel castings to make a completely new set and keep the originals as they are but this may not be possible. According to the LBSC article, Edward made his own patterns for the wheels and then had them cast so they may be an odd size. It looks as though it might be possible to remachine the modified wheels to the normal profile though if all else fails.


I've managed to make room for Monstrous after having a bit of a clear out and moved it to it's new temporary home. It's stood on top of it's box at the moment but I'll see if I can get my hydraulic lifting table back off my brother as that will be ideal to put it on. He's been using it for his American Forney for the last few months.

I took a couple of better photos of the rear driving wheels:



You can see that the outer diameter of the wheel is bigger than the rest due to the extra flange on the outside. Hopefully, you can see the Vee shaped tread in the second photo.

I noticed that the brake blocks have been removed from the rear brake hangers and the hangers themselves are virtually touching the outer flange of the wheel. This makes me think that the loco was originally built with all normal driving wheels and the double flanged rear drivers were added at a later date. The original brake blocks woudn't have worked with the new Vee shaped treads. In fact, looking very closely at the photos in Model Engineer I'm pretty certain that the rear drivers are the same as the rest.

The loco appears to have working steam brakes as there is a brake valve in the cab but I suspect that they won't actually work now as the rear brake hangers will hit the outer flange of the wheel before the other brake blocks contact the treads of the other wheels.

Overall the loco looks in good mechanical condition and there doesn't seem to be any noticeable wear in the motion. I can't see any important bits missing apart from some brackets that the running boards are supported on. The left hand one is very floppy in the middle! The smokebox is quite clean inside and the grate looks in good condition, assuming it is the original, so I wonder just how much running the loco has actually done. It's unlikely to have been run on a normal track due to the modified rear driving wheels so quite possibly the last time it ran was on Edward's own track in his garden. I don't know when Edward died but the last article by him in Model Engineer was in 1954. I'll have to try and find out if his son Michael can fill in a few details.

I think that when I get around to working on this loco I'm probably going to have to remove the boiler to make it more manageable. It's too heavy really to lay on it's side or turn upside down to remove the rear wheels without doing some damage. I'll be able to inspect the boiler more easily as well if it's off the chassis. One problem that I will have when I come to test the boiler is that I'm not sure what the working pressure was designed to be. Neither of the pressure gauges (one in the cab and one on the tender) have a line on them as it wasn't necessary in those days. And, of course, you didn't need boiler certificates so there are none of those. I've just re-read the article and it mentions the safety valves blowing off at 70psi so I guess that is the design pressure.


I've been busy in the garden again so not much time for anything else. My internet connection has been very poor over the last couple of weeks and is absolutely terrible at the moment. I've decided to change my broadband provider at long last but the changeover won't be until 3rd August. Whether I will be able to upload this update after I've written it remains to be seen!

I didn't feel like doing much else tonight so decided to start taking the boiler off Monstrous.

The running boards are only held with a couple of screws so they came off easily and the cab is only held by one screw through the floor so that was easy as well. The reverser is fastened to the cab side but I just had to disconnect the operating rod from the dummy steam reverser halfway along the boiler. It should be pinned but was held on with a bit of copper wire! The actual reversing screw is in the dummy steam reverser and not in the cab.


View of the backhead with butterfly fire doors. The nifty valve on the bottom right is the brake valve


All the valves seem well and truly stuck so I'll have to be careful freeing them off when the time comes. Not sure what the valve is attached to the lefthand end of the main turret but it could have been a whistle valve at some time? Actually, only the valve on the far right valve of the turret is connected to anything and that is the blower. The other three are not used.

The bottom nut of the water gauge looks way below the firebox crown so will need altering or a sleeve fitting, in fact the whole gauge could have benefitted from being much higher up. A lot of the old designs seem to have this problem.

I removed the injector and it's feed pipe to the boiler top feed along with the injector steam valve which has it's own supply from a small turret behind the main one. There was another pipe connected to a fitting at the bottom of the backhead which went to a screwed connection on the drag beam so I think that's for the second pressure gauge mounted on the top of the tender.



I assume that the injector (on the right in the photo above) is a homemade one so it will be interesting to see how it works. It looks the same as the one fitted to the Big Boy. The overflow is just a threaded hole in the body and doesn't have a pipe fitted. The object on the left of the photo is a double clack valve which combines the feed from the injector and the tender handpump into one pipe to the top feed. Apparently Michael has a similar arrangement.

The only other pipe that still needs to come off is the one from the axlepumps to the top feed. I didn't have a suitable spanner to hand at the time. All the pipe unions seem to have flat faces with small flat washers to seal the joints rather than the usual coned joints common today.

None of the connections so far have been very tight and it looks as though bits have been removed but only put back loosely. Most of the slots in the screws are very chewed up as if they have been undone many times.

The smokebox is split so the top part is removeable to get at the connections which is rather nice. All of the fixing screws were loose and most of them seem to have stripped threads so weren't really doing anything.



There seems to be plenty of room in there to get at things. You can see the four element superheater fed by the smokebox regulator. According to the LBSC article, the regulator is 'a big pin valve operated by an eccentric' but I'm not sure what that is. No doubt I'll find out later.

Now I've got the top off the smokebox it looks a lot dirtier than I first thought so the loco probably has done a fair bit of running after all.

There is just the single steam connection at the bottom of the smokebox to undo and the blast nozzle and then the boiler should come off with a bit of luck. I can't see any obvious screws holding the smokebox to the saddle so it may be held by just the blast nozzle.

While I'd got the camera out I took a couple of pictures of the 2 to 1 gear for driving the middle valve and one of the outside cylinders.



The 2 to 1 levers are a very nice bit of machining. The lump between the frames that the levers are mounted on is the lubrcator tank and the lubricator is driven by the movement of the main lever. The shaft that the lever pivots on goes down through the top of the lubricator and there must be a ratchet inside. Very neat but it has the problem that the amount of oil delivered will vary with the valve gear cut off.

It looks as though the lubricator has just one output which feeds into the front of the inside steam chest. I'll see better when the boiler is off but it looks as though the main steam pipe feeds into the top of the inside steam chest and then there are pipes from the side of this feeding the steam and oil to the outside cylinders.


Right hand cylinder


The cylinders are massive and I thought at first they had piston valves but they are actually slide valves. I presume that the sighting plugs in the top of the steam chest allow you to see the ports for setting the valves as the steam chests are in one piece without a separate top cover.


The boiler has four safety valves.


They look a bit rough and all different to each other!


I couldn't upload yesterday's update as the internet connection kept dropping out so will try again today.

As I suspected, the smokebox was only held by the blast nozzle so once that was removed and the steam connection undone the boiler just lifted off leaving the grate and ashpan attached to the chassis.


Front section of the chassis


Rear section




The top of the inside slide bar is very badly scored which suggests it has picked up on the crosshead at some time, probably due to a lack of lubrication.

The exhaust pipes to the blast pipe only seem to be connected to the outside cylinders so there must be some internal passages to connect the exhaust from the middle cylinder to the outside cylinders.


Axle Pumps


The twin axle pumps are driven in tandem by a rocking arm connected to an eccentric on the second axle.




The grate does look as though it's seen a lot of use but should be ok for a bit longer yet. The grate and ashpan can be removed with the boiler in place by removing two supporting pins but the trailing truck has to be removed first. Fortunately, it's only held in place by one nut on the front pivot.

The trailing truck is the normal four wheeled type pivoted at the front with the rear end supported by two spring loaded plungers bearing on the rear of the truck frame.



Here's a photo which hopefully shows the double flanged rear drivers a bit better:



I'm beginning to have doubts as to whether it will be possible to remachine these to the normal profile as the inside flange looks to be further out than the normal ones. I may have to fit steel tyres to them if I can't find any alternative castings.

Now that the loco is separated into two lumps it will be much easier to work on. I can easily carry bits out to the workshop now when the time comes.


As it's pouring down with rain outside I decided to carry on and remove the rear driving wheels.

Firstly though I removed the steam chest cover from the middle cylinder just to have a look at the valve and the ports.



I was expecting the ports to be much larger considering the size of the cylinders but these are not much larger than the ports for a normal sized 2½" gauge cylinder. At a rough guess they are 0.125" wide by 0.625" long. One of the ports has a small nick in the inlet side so that could do with repairing if possible.

The valve had a lot of play in the drive - about 0.125" - due to wear in the valve pins etc. so there would have been a lot of lost motion when running. That's the major problem with conjugated valve gear drives - it only takes small amounts of wear in the outside valve gear to seriously affect the travel of the inside valve. Hopefully the problem can be sorted though.

There wasn't much sign of any oil in the valve chest but the port face seems ok with no signs of serious scoring. The superheat is no doubt quite low so the steam would still be pretty wet and help to lubricate everything. I have serious doubts as to whether the outside cylinders would have received their fair share of any oil put in by the lubricator. The oil inlet is right at the front of the steamchest well away from the steam inlet at the other end and I reckon that the steam to the outside cylinders would go straight out the steamchest without picking up much oil. It really wants the oil injecting into the main steam pipe before it enters the steamchest but that would not be easy to do. What I could do is attach a small diameter pipe to the outlet of the oil clack inside the steamchest and stick the end up inside the steam connection on the valve chest cover. That should help a bit.

I managed to remove the rear drivers fairly easily after dismantling some of the motion. I couldn't get the big ends of the connecting rods off the crankpins easily as they are ball races and a press fit onto the pins, therefore I couldn't get the coupling rods off. Fortunately, there was enough play in the coupling rods to be able to gently spring the ends of the coupling rods over the rear crankpins. One of the hornstays only had one screw in it and the other had no screws at all! I've noticed that there are quite a few screws missing in various places.



I was a bit puzzled at first by the shaft and lever mounted onto the rear axle assembly. There is a long lever at the back of the cab that wasn't connected to anything which I assumed was to operate cylinder draincocks but the linkage was missing. When I saw the shaft on the rear axle assembly I thought this was an intermediate shaft for the drain cocks. Once I removed the axle from the chassis I noticed that the ends of the shaft have cams on them that bear onto the hornstays on either side. I now think that the lever in the cab was to operate these cams. Pulling on the lever would press the cams against the hornstays and lift the loco chassis, putting more weight on the axle and hence the grooved wheels, possibly improving tracton? It's all a bit out of line at the moment as the spring pins on the axle boxes have got bent at some time.

Looking closely at the wheels I saw that the grooved treads are actually separate from the wheel centres so it looks as though Edward modified the original wheels by turning off the normal treads and fitting the grooved ones. That's good as hopefully I can remove the grooved tyres, fit new ones, and machine as normal. I won't feel so guilty now as I can preserve the grooved treads rather than have to destroy them by machining them off.


Had an hour tonight so had a go at getting the tyres off the trailing wheels. It wasn't quite so simple as I expected (should have known better!) as the tyres were also pinned to the wheel centres with threaded screws. They had been put in and then the heads sawn off. I realised this after heating one tyre over the gas ring on the cooker and trying to remove it. It came loose but wouldn't come off. That's when I spotted the pins. I managed to drill them out with a 2mm carbide endmill fairly easily though and then the tyres just tapped off. One of them seemed a very loose fit and I'm not sure if they weren't glued on with something before being pinned. They certainly weren't a shrink fit. Presumably they would have had a suitable type of glue in the 1940's?



Now I need a couple of slices off some suitable thick wall steel tubing to make the new tyres.


A chap at the club just happened to have some bits of 4" diameter steel bar and on Thursday he brought me two pieces about 5/8" thick which were ideal for making the new tyres (thanks Geoff!). Unfortunately though, it seems like this will be as far as this project goes. I got around to testing the boiler today and I think it's scrap. There are 7 or 8 leaking stays inside the firebox, which I could probably have repaired but, much worse, there is a really bad leak in the combustion chamber. This seems to be coming from the tubeplate end and is impossible to get at to attempt any sort of repair from inside due to all the water tubes. The final nail in the coffin is that once I turned the boiler upside down I saw that the crown of the firebox and the rear section of the combustion chamber have a big bulge in them. It looks as though the crown stays have come adrift, probably from the outer wrapper. I think this is what happened to the first boiler that Edward made where the stays were not soldered to the outer wrapper properly and it looks as though Edward had the same problem again. It perhaps didn't show up on the initial tests or the boiler has been subjected to too much pressure at some point.

I'm really miffed as I was really looking forward to running this loco again !!!!!! Looks as though it's just going to have to be a static display model.


I haven't done any more to Monstrous as I'm concentrating on getting the 5" Mogul finished but I've decided to have a go at repairing the boiler after all. There's nothing to loose if it isn't successful so why not? It will have to wait though until I have the time to do it.

I've bought a small USB camera off Ebay (only about £7) that plugs into the PC and that is small enough to get inside the boiler. The head is 8mm diameter and can be got with leads up to 10 metres long. It has 6 LEDs on the end to illuminate the objects in dark places. Ideal for boilers! I can now have a look inside to see what's what.

The crownstays are fine and still properly attached so I think the bulge in the firebox crown is due to the boiler being subjected to excess pressure or maybe low water level allowing it to overheat. I think it will tap out and be ok. The leaking stays in the firebox are repairable but it will be a devil of a job to get things clean enough to recaulk them with Comsol.

Using the new USB camera I managed to have a look at the combustion chamber inside the boiler and there seems to be some sort of bolt from the top to the bottom almost at the tubeplate end. This seems to have been sealed with gasket goo (looks like Red Hermatite or similar) and I reckon it's that that is leaking rather than a failed soldered joint. I have no idea what this 'bolt' is for but it seems to have been fitted after the boiler was made. The bottom of the barrel has a cover underneath the nut of the bolt (like an upside down dome) which was probably also fitted after the boiler was made.



The boiler also has a normal steam dome on the top but this is about 1 inch further forward than the head of the 'bolt' through the combustion chamber.



The holes in the combustion chamber could have been drilled from the bottom through the access cover and then the bolt could have been fed through the steam dome at an angle and fed through the hole in the top of the combustion chamber. A bit fiddly to do but possible. As mentioned though, I really don't know why this was done. I thought at first it was to block off a leaking vertical water tube in the combustion chamber but the bolt goes between them.

Just got the USB camera out and this is the head of the bolt on top of the combustion chamber:



I guess the spigot on top of the bolt head was to hold the bolt with maybe pliers whilst it was manouvered into place. You can see the red sealant around the bolt head.


Another couple of views inside the boiler while I had the camera out:


View over top of combustion chamber towards backhead




View of tubes looking towards front tubeplate


Now I look at that first photo showing the bolt head, it looks possible that there may be a water tube where the bolt is. I'll have to try and remove the bolt.


I had a go at getting the bolt out tonight. It wouldn't come out in one piece but the head was a separate piece screwed onto the shank and I managed to separate the head quite easily by holding the 'pip' with some cranked pliers and then unscrewing the shank by gripping the bottom end. It was sealing off a water tube after all. It's difficult to tell whether the actual tube was leaking or one of the joints where it is soldered to the combustion chamber wrapper.


The blocked off water tube


I had a good look at the inside of the tube and it became obvious what the problem was. The tube was physically distorted and damaged and actually had a big hole in it!


View inside water tube from the bottom end


The only way I can think of that this damage has occurred is someone has driven something through the tube from the smokebox end. It's inline with the centre fire tube on the second row up from the bottom and I reckon whoever did it must have driven a rod through the fire tube, maybe trying to clear a blockage? They must have been very heavy handed and driven the rod out the end of the fire tube and through the water tube behind. Oh dear!

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