August 2024

Firstly, a bit of news about the boiler. The calculations which Jon Whalley has been preparing, along with a 3D CAD model of the boiler prepared by Bob Yates, has been submitted to British Engineering for design approval. The boiler inspector has come back with some questions, but they are quite reasonable and we hope to be able to answer them satisfactorily. We have our fingers crossed that we can get the design approved soon!

The August working party took place over the bank holiday weekend, so we spent several days working on the C2. Andrew, Dave 2 and Erle started work on Saturday, with Dave 2 and Andy joining on Sunday but working through until Tuesday. Jon spent Sunday with us, which increased the activity further.

Andrew and Dave 2 spent Saturday assembling the reverser reach rod. The reach rod runs alongside the boiler barrel, and then steps out around the firebox, so there is a misalignment which needs to be accommodated between the two ends of the reach rod. The depot at Dahuichang had cobbled together a reach rod from some 1" pipe with two 90 degree elbows to form the joggle. Needless to say, the elbows were not up to the task and had fractured, so scraps of welding rod had been stitched across the fracture to try and hold it all together. A real mess!

The new draincock reach rod is similarly made from 1" pipe (which is actually like the original design), but we have come up with a more elegant design. The joggle is provided by a gently bent section, which is connected to the front and rear sections with in-line connectors. Not only does it look neater but it should also be a lot stronger.

Dave 2 had previously made the joggled section, so it was time to cut it to length and fit it to the other sections. The ends of each section are threaded so that they screw into the in-line connectors. Assembling the whole reach rod allows us to check that the joggle is of the correct dimensions, and will also allow us to design the reverser reach rod which has to fit alongside the draincock reach rod.

With thoughts turning to the reverser reach rod, Dave 1 formulated a plan for refurbishing the intermediate crank which sits between the front and rear sections of the reach rod. The holes in the crank and reach rod ends will need drilling out (so that they are round!) and oversize pins will need to be made. It seems logical to therefore make the bushes out of plastic and the pins from stainless steel, as we have done at the front of the reach rod where it connects to the reverser weighshaft crank.

The pin on the central pivot bracket is heavily worn, and is significantly undersize. Dave 1 mounted the pivot between centres on a lathe, and took readings of the eccentricity of the pin. Fortunately the wear appears to be fairly even around the pin, so it will not need to be turned down much to make it true again. A stainless steel sleeve can then be made to fit over the pin, and an off the shelf plastic bush bought to fit into the centre of the crank.

The intermediate crank itself would benefit from a good dose of flap wheeling, to smooth the currently very rough surface. Once all the above work is done, the crank and pivot should be fit for use and appear far more presentable.

Erle has continued to work on machining the reverser base plate. This is really taking shape now. He has drilled the mounting holes, and the holes for fitting the cut-off indicator plate. A discussion was had about why the cut off graduations were a different length in reverse gear to those in forward gear. Looking at the valve gear drawings it can be seen that the valve gear is not designed to be symmetrical between forward and reverse. This is common with lots of other locos. In the end it was decided that the indicator plate should be mounted such that the mid gear position is not exactly half way between full forward and full reverse gear, due to the asymmetry of the valve gear

Andrew continued to manufacture the stainless steel expansion link trunnion sleeves which he had started at the previous working party. The inside and outside diameters have to be very precise, as they need to be a press fit onto the expansion link trunnions while providing a running fit inside the motion bracket bushes. This means that it is not a quick process to turn each sleeve. But by the end of Monday, the three outstanding sleeves were complete. Next stage will be to fit them to the trunnions, probably by heating the sleeves in the oil bath to shrink them on.

Andy has started to refurbish the cylinder and valve glands. We have previously looked at these and, while the valve glands appear to be as per the original design, the cylinder glands are quite different.

The valve glands are a traditional rope packing design. Hopefully, if we replace the rope packing and repair any broken parts, it should be a simple task to refurbish these glands.

The cylinder glands are formed of a series of 'iris rings', three pairs per cylinder. Each pair is contained within a steel 'cup'. A spring wraps around each iris ring clamping it onto the piston rod and forming a seal. To stop steam escaping round the outside of the iris rings, they push up against the end of each cup. There are extra metallic packing rings at the end of each gland, but when we dismantled the locomotive we did not find any springs which we would expect to be there to keep the assemblies tight against each other. We need to try and understand this.

Using emery paper of varying grades, Andy has cleaned up the cups which contain the cylinder gland iris rings, along with some of the additional packing rings. He paid particular attention to the faces which need to be smooth to form a seal. The iris rings do not appear to be badly worn, so we are tempted to re-use them. We have no drawings of them, and do not even know what they are made of (some sort of plastic by the look of it), so it will be difficult to get them re-made. They are clearly designed to accommodate a significant amount of wear, which gives us some confidence that they have a reasonable life left in them. To clean the iris rings, Andy has left them soaking in oil. To keep the newly cleaned steel parts free of corrosion, he applied spray wax to them.

While Andy was cleaning the parts which form the interior of the cylinder glands, Jon painted the castings which contain the glands. These had been primed some time ago, but had been kept in a heated cupboard to prevent them corroding. Applying paint will form a more permanent barrier against corrosion.

While he had the paint can open, Jon also applied a second coat of paint to the hooks, loops and shackles which make up the safety chains between engine and tender.

When we mocked up the cab controls a few months ago, we placed the firehole door and carrier ring in place to make sure there was sufficient space to swing them. The firehole door ring was covered in flaking rust, which was making a bit of a mess in the cab, so Jon took it outside the shed and gave it a good wire wheeling to remove the scale. It is now much cleaner to handle.

We are also aware that the firehole door ring is cracked. Since we have no drawings of it (it is a Chinese modification) we don't know what material it is made of. Hopefully it will turn out to be cast steel, since that is much easier to weld than cast iron. We'll test it at a future working party.

All the components (shaft, cranks, pins and keys) which form the reverser weighshaft are now complete, so Dave 2 was tasked with assembling it. Some of the pins were a very tight fit into the holes in the cranks, so Dave had to emery them a little before the hydraulic press could push them into place. The cranks could then be pushed into place on the weighshaft itself, using a mallet to force them into place.

Unfortunately the cranks had been left out after being primed some time ago, so had begun to corrode again. Dave 2 therefore cleaned the corrosion off, and Dave 1 applied a new coat of primer.

Another cleaning job which Dave 2 applied himself to was the expansion link side plates. Andrew has finished truing up the trunnions, and so running a flap wheel over the plates makes them look presentable again.

To complete the expansion link side plates, a small keyway slot is required in a couple of the plates. This holds a key which prevents the return rod pin rotating in the bosses on the plates. We want all the motion to occur at the bushed interface with the rod, and not at the interface with the plate where wear is more difficult to repair. The keyway was part of the original design, but was not present in the plates as we received them. That could explain why we had to replace the bosses on the plate due to severe wear! Dave 1 set up the pair of plates on the CNC milling machine, and Andrew used it to mill the slots.

With all machining on the expansion link side plates now complete, Dave 1 degreased them with white spirit and applied a coat of primer to all four plates.

Since the weather was warm, if rather wet, paint and primer dried overnight, allowing Dave 1 to apply more coats the following day. The expansion link side plates were painted black, and a second coat of black was applied to the cylinder gland castings which Jon had painted a couple of days earlier. The reverser weighshaft cranks were painted in a grey undercoat, as they will ultimately be painted red.

We had previously discovered that one of the holes in one of the lubricator drive brackets (which bolt to the expansion links) did not align correctly with the corresponding hole in the side plate. The holes have to be accurately aligned since fitted bolts are used to hold the entire assembly together. Dave 2 therefore used a file to carefully 'move' the offending hole.

With work finished on the lubricator drive brackets, Dave 1 cleaned them and applied primer. He also cleaned and primed the draincock operating rods. These will all be ready for painting at the next working party.

And so finished a very busy and productive working party. It was great to have a good number of people all working on different jobs in parallel, but helping each other when necessary. With that intensity of activity, we feel we have made significant progress.