C2 Project News

Late January 2019

Cylinders and Motion

From all the measurements of the coupling rods which Erle has taken over the previous working parties, it was apparent that one of the rods was not quite straight. So Paul and Dave 1 started the working party by learning how to straighten coupling rods.
On Friday morning Paul and Dave 1 set up a jig using parallels, so that we could tell when the coupling rod was straight. We set it up using one of the rods which we knew was straight to start with.
The straightening couldn't be done on the jig. Robco recommended that we use the hydraulic press to apply force to the middle of the rod, with the ends of the rod supported on blocks. Using a dial test indicator to measure the deflection was a very helpful piece of advice.
The rod is quite springy, so the deflection of the middle of it caused by the hydraulic press was mostly within the elastic limit. But after a couple of cautious presses, a small permanent set was observed. The effect seemed very small, so we were tempted to give the rod a bit more. But caution overcame, and the rod was taken to the jig for assessment before proceeding further. It's a bit lucky we did, as the rod was now straight!
Paul continues to work on researching the history of the C2 class and is writing a book on the subject. He is collaborating closely with several other researchers, including Robin Gibbons and John Athersuch who are working on a book about the Chinese narrow-gauge railways. Robin and his wife came to visit us on Friday to see progress, borrow some old Chinese books, and to bring us a gift!

The gift is a loco numberplate acquired from the Weihe Forestry Railway, number SW-21055. This loco was unusual - it was one of just two 28t locos built at Dunhua Forest Machinery Factory in the late 1970s. They appear to have been built to the Harbin C2 drawings, and later acquired Harbin-built bogie tenders.

Thanks Robin!
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Loco numberplate from the Weihe Forestry Railway. These were common on some C2 fleets, especially the forestry lines. As far as we know, ours only ever had its number painted on. This was a gift from Robin Gibbons and we are considering whether to keep it or sell it for additional funds.
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Another interesting chunk of aluminium we have recently acquired is this worksplate from a 28t loco built at Shijiazhuang. Strictly this would be a ZM16-4 class, though they were very similar to the C2s built at Harbin and the term C2 is now commonly applied to locos from both factories. Sorry, this one isn't for sale!
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SW-21055 at work at Weihe Forestry Railway in 2000. This was the last forestry railway to use steam locos as its main traction; most others had closed or dieselised by this time. (Photo: Don Bell, Paul M-B collection)
Erle arrived the following day, and re-measured the formerly bent coupling rod, and then updated his drawing of it. Everything fits together much better on the drawing now.
For homework, Dave 1 had carried out a check of Erle's motion assembly drawing the previous week, using a spreadsheet. Although there is a little more drawing work required, we are now in a position where we can finalise the coupling rod lateral centrelines, and can start to draw up the coupling rod bearing covers (which hold the coupling rods in their lateral position).

Due to some of the crank pins being very slightly over length, we want to machine the rear of the crank pin end caps to ensure that they correctly clamp the inner races of the coupling rod roller bearings. So Dave 1 found a bar of steel and turned up a mandrel to hold the crank pin end caps while they are turned.
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A 3D print of a connecting rod bearing cover. We'll have to machine these from steel, but this plastic one will help us to validate the exact dimensions that we have determined from Erle's drawings.
Whenever we take any measurements, to enable us to do some homework, it is inevitable that there will be one dimension which wasn't recorded. Erle had previously measured and started to draw the return cranks, but spent some time this working party measuring the bits which had been missed last time. He also took a set of measurements of the combination levers, so that he can start to draw them up. These are components which we won't need in the immediate future, but are useful to have on the assembly drawing so that we know how everything fits together.
Dave 2 arrived on Friday afternoon, and recommenced his work on the blowdown valve levers. The bearing brackets are rather crude, and we will probably remake them both. However, the levers are quite nice, with neatly shaped handles on the ends, which Dave has polished up.
The blowdown valve lever bearing which was seized put up quite a fight, and Dave 2 had to cut it apart in order to separate it from the lever. He has saved the critical parts though, so we can make new ones to a similar pattern.
Ed (Erle's son) also joined us for a few hours on Friday afternoon. He turned his attention to the second draincock pivot bracket, which had been soaking in diesel oil since last working party. the oil had done its trick, and the pivot was now free. But, unlike the pivot which he disassembled last time, Ed could not knock out the pins holding the assembly together.
James arrived on Saturday, and took over from Ed on the draincock pivot bracket. The pins steadfastly refused to move. So the only thing for it was to cut the pivot shaft and then drill it out of the levers. Even this was not as easy as it should have been, since the pins are probably of a harder material than the shaft. James spent all day sawing, drilling, grinding, and hammering, but it was Sunday morning before all the parts were disassembled.
The cylinder alignment jigs which Alan made previously were ready for use, so now it was time for a trial fit of the cylinders and motion brackets, so that some measurements could be taken. We didn't fit any packer plates behind these components (although we know we will need them for final assembly) so that we have a known starting point. Alan and Andrew worked together, lifting each component into place with an engine hoist, then bolting it onto the frames with the old fitted bolts we had taken out originally. We'll make new fitted bolts for the final assembly.
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Alan and Andrew position the first cylinder for its trial fit to the frames.
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With both cylinders bolted in place, Alan and Andrew position one of the motion brackets.
Fitting the cylinders and motion brackets changes the appearance of the locomotive chassis dramatically, adding significant width to what had previously appeared a very narrow frame. We think it's starting to look like a steam locomotive again!

On Sunday Alan fitted the cylinder alignment jigs, and the bars which run along the cylinder centrelines. The bars are a perfect fit in the jigs Alan has made, so we are confident of the arrangement giving us good results when we use it to check the cylinder alignment.
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With the cylinders and motion brackets trial-fitted on both sides, we can start to check the alignment using the X-shaped jigs made by Alan.
While this was going on, Paul sat at his computer drawing up profiles for more brakegear components. With only one or two exceptions, all the locomotive brakegear components are finished, but there are still some required for the tender brakegear. It is our intention to get these profiles ordered in the next few days, so that we can work on them at the next working party.
Having finished work on the blowdown valve levers, Dave 2 took some of the brake rodding and cut the lugs off the end. These are the lugs which will be replaced by the new profiles drawn up by Paul.
The coupling rod bearing covers are disks of steel, shaped on both sides. Working out how to make them is not so obvious, so Dave 1 had to do some head scratching. With Alan's assistance we now believe we have a process, and Dave 1 has started to draw up the necessary mandrels. Dave 2 cleaned up a suitable bar of steel, which Dave 1 will use to make the first mandrel at the next working party.
While looking at the coupling rod bearing covers, Dave 1 put together a list of material requirements, so that Paul can add them to his order for profiles.
Paul made an early start on Sunday, trueing up the slide bars on the surface grinder. It was a slow process, taking most of the day, but we now have some perfectly flat surfaces to measure to. This makes taking measurements a lot more accurate. A coat of wax sprayed onto the ground faces protect will protect them from corrosion.
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Paul at the surface grinder, working to true up the slidebars
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The slidebars are now ready to be trial-fitted for an initial measure up to check the alignment.
Once Alan has finished measuring the cylinder centrelines, the jigs can be removed and the cylinder rear covers temporarily fitted, the slidebars being bolted between the cylinder rear covers and the motion brackets. This will allow us to measure the slidebar alignments, which in turn will allow us to derive the clearance behind the crossheads, and thus to ultimately decide how much packing we need behind the cylinders and motion brackets.
Having spent Saturday measuring and drawing motion parts, Erle had enough information to be able to continue his drawing work at home (except the one dimension we've forgotten to take, of course!). So he turned his attention to the mechanical lubricators on Sunday. We have two subtly different types of lubricator, but we're not sure whether the differences are significant or not. Erle is looking over them in detail, to try to understand how they work, and to decide which is for lubricating oil and which is for steam oil.
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Anatomy of a mechanical lubricator. We have three of these plus some spares, and require two for the loco. Erle is preparing to refurbish all three.
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One of the lubricators, partially dismantled.
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The pump units from a mechanical lubricator: there are 14 pumps in each one.
After his victory over the draincock pivot, James cleaned up the draincock operating pedal. This is a Chinese modification; why use a hand operated lever when you can just put your foot on a pedal?
Boston Lodge have been building two steam brake cylinders for us, one for the engine and one for the tender. The cylinders themselves are complete, although they are still awaiting some of the internal components. James retrieved the cylinders from the machine shop, and gave them a good clean with a wire wheel to remove any surface corrosion. At this point we discovered we had run out of heat proof paint, so they will have to wait before being painted. Fortunately, one of the new cupboards which Dave 2 obtained and installed for us has a trace heater in it, and this is effective at preventing corrosion getting started.
While using the hand held wire wheel, James reported that it was occasionally cutting out. He suspected it was a loose wire in the terminal box. In no time at all, Dave 2 had got his screwdriver out and had fixed the problem. It sometimes seems like there is nothing Dave 2 cannot fix; a very useful chap to have around.
Paul had found a moment on Saturday to apply some primer to damaged areas of paint on the brake weighshaft and bearings. By Sunday afternoon the primer was dry, so Andrew applied a layer of top coat. The rack which Dave 2 built has a bar on which to hang items being painted, and this was put to use for the bearings (the weighshaft is a bit too heavy). While the tin of black top coat was open, Andrew applied another coat to the underside of the stretcher which was ground back last working party.
While refitting the cylinders and motion brackets (albeit temporarily) was undoubtedly the most impressive accomplishment of the weekend, we have also made progress on many small items too. It's those less glamorous jobs which take much of the time, so getting them done is very pleasing.
We'll be back again in about a week's time for the next working party, and looking forward to making some more progress.
Mid February 2019  
Mid-January 2018