C2 Project News

May Day 2019

Early May bank holiday weekend working party

Andrew and Dave 1 started the working party with a planning session on Friday. The whiteboard in the C2 Shed was filled with potential jobs, so that we can employ anyone in search of something to do.
Much of the rest of Friday was spent carrying out minor tasks, but ones which it is nice to get done. Tidying the workbench in the C2 Shed, which tends to get used as a dumping ground for work in progress, makes it a useful space again. And the information boards, which we took down to make space for the racking, are now hung up where visitors to the shed can see them again.
We also took the opportunity to talk to the works staff about completion of the steam brake cylinders. Martin is awaiting some circlips and a dimension for machining the brake crank pin hole. Wol provided a specification for the circlip, so we'll ask Dylan to purchase some, and we'll let Martin know what size of brake crank pin we're using. Andrew and Dave 1 also had a look at a bogie which was under the frames of the new double engine, to see how the steam brake cylinders are installed. This enables us to understand how the brake pipe is attached to the cylinder.
Mike, Matt and Dave 1 all took turns at descaling the remaining crashbeam profiles. The inside radius of the brackets which bolt to the bufferbeams had been creased by the bending process, but, being quite visible, we want them to look neat. Special effort was therefore taken to remove the ridges; not so easy on the inside of a curved surface. But after a couple of days the job was complete, and the next stages of the build process could start.
Andrew used the band saw to cut the curved brackets to length, and he and Dave 1 used the Wanderer milling machine to square off the cut ends. The front brackets have a shaped top edge, which required the brackets to be mounted at an angle in the band saw. Andrew then carefully marked out and, assisted by Matty, drilled the holes in the brackets.
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Front crash beam brackets drilled and marked up ready for cutting - Andrew Nelms, May 2019
Front crash beam brackets on the band saw being trimmed to the correct shape - Andrew Nelms, May 2019
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We don't want to weld up the crashbeams in situ, as that would damage the paintwork on the buffer beams. So Dave 2 took a section of channel, marked it out and drilled a series of holes on which the front crashbeam can be mounted for welding. The rear crashbeam is a little more tricky, as we don't know the exact hole centres in the rear bufferbeam (the front bufferbeam is new, the rear bufferbeam is the one we inherited from China). The approach there will therefore be to lightly tack weld the crashbeam components in situ, then move the assembly to the jig, drill holes through the holes in the brackets, such that the assembly can be then bolted to the jig for full welding.
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Front and rear crash beam brackets in progress on the bench - Andrew Nelms, May 2019
Tender rear crash beams trial mounted on the rear of the tender - Andrew Nelms, May 2019
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The brakegear consists of many links with pinned and bushed joints. To increase the surface area of the pins and bushes, and hence to hopefully reduce wear rates, we are fitting bosses to the links, such that longer bushes and pins can be used. Paul and Dave 1 ground weld preps around the edges of the bosses Dave 2 turned up at the last working party, and Andrew welded them onto the tender brake hangers.
The slotted end of the handbrake slotted links is also wider than the link itself, but the 'boss' couldn't be turned because of its elongated shape. These components were therefore made from material of the same thickness as the slotted link 'boss'. Alan reduced the thickness of the remainder of the link by use of the Bridgeport milling machine. The pin hole at the other end of the slotted links also has a boss, but on the other side, so Andrew welded that on in the usual way.
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Alan machining the slotted link profiles on the Bridgeport milling machine - Paul Molyneux-Berry 2019
Completed tender handbrake linkages. The slots allow the brakes to be actuated independently by the steam brake cylinder. - Paul Molyneux-Berry, May 2019
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A few months ago we ordered profiles for the lugs on the tender brake pull rods, to replace badly worn parts. Paul set up an assembly in the welding bay, and Andrew welded the lugs on. One of the original pull rods was of far heavier section than necessary, so Paul cut to length a new piece of rodding to match the other pull rods. Dave 1 cleaned it with a wire wheel, Paul set up the assembly, and Andrew again welded it together.
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Tender brake pull rods welded up by Andrew. - Paul Molyneux-Berry, May 2019
Most of the holes in the tender brakegear components require machining out to 34 mm diameter, in order to accept plastic bushes. Dave 2 therefore used one of the Asquith pillar drills to drill out and ream the holes in the lugs of the tender brake pull rods. He also drilled and reamed a hole in one end of each tender brake hanger. Meanwhile, Paul devised a mounting jig on the table of the Bridgeport milling machine, to enable the other two holes in each hanger to be quickly machined at the correct centres. The jig arrangement made aligning the hangers very quick and easy. Nevertheless, there are a lot of holes to machine, so it took Dave 1 a full afternoon to mill all the holes in all six of the tender brake hangers.
Dave drilling out holes on the tender brake linkages - Paul Molyneux-Berry, May 2019
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The tender brake stretchers required holes for split pins to be drilled in the stainless steel pins at each end, which Dave 2 successfully carried out. Working with stainless steel is not quite as easy as it is with carbon steel, but does not necessarily pose a problem so long as the feed rate is maintained.
To finish off the tender brake stretchers, Paul and Dave 1 pressed the plastic bushes into the centre holes in the stretchers. These components are now complete, and have been placed on the rack of shelves which hold our large collection of completed brakegear parts.
While much of the above work was focussed on crashbeams and brakegear, we hadn't forgotten that we are also working on the cylinders, motion brackets, and associated parts. Dave 1 started by removing the slidebars, the positions of which had been measured at the previous working party.
Next to receive attention were the oil pots on top of the motion bracket bearings. With some of the oil pot caps missing, the pots were almost solid with dirt, which Dave 1 dug out. He and Paul then gave the motion bracket bearings a good dose of looking at, and concluded that the bushes are worn and will need replacing. Daves 1 and 2 therefore pressed out the bearing bushes that didn't fall out of their own accord!
The motion bracket oil pots are not part of the mechanical lubrication system, and so have to be manually topped up during engine preparation. This is an antithesis to the C2 philosophy of minimum work for engine crews, and so we were on the lookout for alternative solutions. We know we will need to go round the locomotive with a grease gun about once a fortnight, so that is a possibility, but the motion bracket bearings are not suited to grease lubrication. After much thought, Paul and Dave 1 concluded that Vesconite (plastic) bushes in the motion brackets appear to be feasible, if coupled with stainless steel sleeves on the expansion link trunnions, and should be self lubricating. We will have to change the geometry of the bearing interface slightly to suit the materials, but it is easy to change back to the original design using steel bushes if the new materials don't work as well as we hope.
With a decision made about how to go about rebushing the motion brackets, it appeared that reaming out the motion bracket bearing housings was the next step. This could be done on the big Asquith pillar drill, which conveniently has a crane over it. Matt and Dave 1 therefore removed the motion brackets from the locomotive chassis, and the following day Matt and Alan moved them into the erecting shop.
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Moving the motion brackets to the Radial Arm Drill in the erecting shop - Paul Molyneux Berry, May 2019
The nominal hole diameter in the motion brackets is 50 mm, but since we know that some of the bushes were loose and the housings fretted, reaming the holes out to 2" (50.8 mm) diameter seemed the sensible thing to do. Alan and Matt mounted the motion brackets onto the table of the Asquith, such that the holes were vertically aligned ready for reaming. Paul suggested placing a smaller diameter reamer through the holes first, just to check that they are in true alignment. It was a very good suggestion, as we then discovered something rather horrible. The holes which hold the trunnions on the expansion links are misaligned by up to 2.5 mm! A similar check of the other motion bracket showed the same problem. Quite how the motion worked with this level of misalignment we are unsure, but it probably explains some of the wear we noted in the bushes.
Alan and Matt setting up the motion brackets on the radial arm drill - Paul Molyneux Berry, May 2019
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A view showing the misalignment between the top and bottom holes on the motion brackets - Paul Molyneux Berry, May 2019
A misalignment of 2.5 mm is far more than can be corrected with a reamer, so a change of plan is required. We will have to bore out these holes on the horizontal borer in order to eliminate the misalignment. Fortunately we have already talked to Martin about using the horizontal borer to restore the slidebar mounting holes on the motion brackets, so we hope to be able to carry out both operations while the motion brackets are on the machine. Alan and Matt have documented the misalignment, so we can formulate a plan for re-machining the holes.
All was not lost however; while the motion brackets were on the Asquith, Alan and Matt took the opportunity to drill out a couple of holes which had been flame cut in the brackets. The holes permit the oil feed pipes to pass through the motion brackets on their way to the crossheads, so aren't terribly critical, but they look a lot neater now.
Matt and Alan drilling holes in the motion brackets - Paul Molyneux-Berry, May 2019
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Erle has been continuing his work on the lubricators. Using some offcuts of brass, he has started to turn up the ferrules which hold the lower strainers together. The lower strainers also require a flat armature plate through their centre. The originals were made of steel, and were quite rusty. Erle has suggested making new ones from stainless steel, and we support this idea. Andrew is looking into getting some armature plates profile cut, since they are a complex shape including many cut-outs.
Using the gaskets he ordered recently, Erle has started reassembling the overhauled oil pumps into the lubricators. But how many do we want in each? As bought, the cylinder oil lubricator contained nine pumps (four cylinder ports, two cylinder glands, two piston ports, and one steam brake cylinder), and the bearing oil lubricator contained ten (eight axleboxes and two slidebars). But we are adding an extra steam brake cylinder to the tender, so we need an extra oil pump in the cylinder oil lubricator. Each lubricator can accommodate 14 oil pumps, and we have a spare lubricator to provide any extra pumps we need, so it's straightforward to arrange.
According to the Nathan manuals we have for the lubricators, a non return valve should be fitted immediately after each pump and a pressure relief valve fitted at the point the oil is injected into whatever it's lubricating. This keeps the delivery pipes pressurised, ensuring that there is immediate injection of oil as the lubricator is operated. That is how the cylinder oil system is arranged on our C2, but the lubricating oil system is different. Since the lubricating oil pumps deliver oil to reservoirs in the axleboxes and crossheads, the pipework does not need to be pressurised, and so there are no pressure relief valves. At last some of the detail of the lubrication system is becoming clear to us!
Andrew attempted to practice welding Chinese text, which we will have as the treads on the front and rear loco/tender steps. Not too bad for a first attempt but more practice required before welding the real thing. A way to mark out the text which can be seen through a welding mask needs to be found.
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Andrew`s first attempt at welding Chinese text (or indeed any text). Andrew thinks a bit more practice will be needed before welding the treads on the loco and tender steps. This is the Mandarin character for Safety - May 2019
Whilst all this was going on, the Ffestiniog and Welsh Highland Railway was having a busy weekend, with no less than 8 steam and 1 diesel locomotive out pulling trains.
Three Fairlie locomotives on Saturday morning at the start of a very busy day on the Railway! - Andrew Nelms, May 2019
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Late May 2019