C2 Project News

Mid-January 2018

No heavy snowfall in Wales (yet!)

C2-800-1203v2.jpg
Andrew is enjoying the snowy slopes in Europe this week!
There isn't a lot to do in mid January other than ski-ing, and there's generally too much snow in Europe for that, so how better to fill the time than with an extra C2 Working Party? We started on the Friday with a bit of a planning session, as we often do. What needs to be done at the working party, and what other jobs can we line up should we have the assistance of other volunteers.
First job was one that needed to be done urgently; the application of paint to the draincock weighshaft bearing brackets, to stop them going rusty. Paul wielded the paintbrush, and it didn't take long to paint the brackets. While the can of paint was open, one of the doors of the new cupboard also received a coat of paint.
In addition to the cupboard and filing cabinet which Dave 2 had retrieved from the skip previously, he had also found some lengths of discarded Dexion with which to make a rack of shelves. Firstly, with the assistance of Dave 1, the display boards (now rather out of date, as much new information has come to light since 2007) on the end wall of the C2 Shed were removed. This created space to install the shelving rack. Dave 2 then planned and assembled the components. By careful planning, there is space under the lower shelf for the gas set, so it's tucked neatly away. And we now have considerable extra shelf space for finished components which are awaiting fitting to the locomotive.
C2-800-1200v2.jpg
Dave's new set of shelves, with space for the gas bottle trolley underneath.
We will get a new set of display boards made, with all the latest information, since we know that many people who visit us in the C2 Shed like to have a look at the boards.
Although just about all of the components for the locomotive brakegear are now completed and ready for fitting, we can't fit them as some of the brackets fit to the motion brackets, and we can't fit them until we know what packing to fit behind the cylinders, and we can't fit them until.... You get the idea. However, we can start trial fitting some parts.
Paul and Dave 1 decided to trial fit the brake weighshaft. One of the bearings was a little tight, so Paul fettled it to give a nice free fit. Then the shaft was lifted into place under the frames, and the bearings slid on. Except that one of the bearings couldn't be fitted because the crank on the weighshaft fouled on a frame stretcher. Bother! We knew that that stretcher would be close when we redesigned the rear dragbox, and we tried to avoid a clash, but something must be not quite to drawing.
The foul was not big, and only a few millimetres of metal needed to be removed from a corner of the stretcher plate. It would be very easy to do if the locomotive chassis were over a pit, but with much trackwork going on at Boston Lodge at present, we can't get the chassis out of the C2 Shed. So Paul lay on his back under the frames and used an angle grinder above his head to make the adjustment. Not the most comfortable of jobs, but after a few iterations of grinding then trying to fit the weighshaft and bearings, a clearance was obtained, everything fitted into place, and the shaft could rotate freely.
C2-800-1192v2.jpg
Loco brake weighshaft and crank now trial assembled, seen here from the driver's side. The steam brake cylinder will bolt on to those four holes on the left.
C2-800-1193v2.jpg
Loco brake weighshaft and crank now trial assembled, seen here from underneath. Oh, and the photo's inverted!
The weighshaft bearings bolt onto the locomotive chassis sideframes, and we know that they are not straight in that area. As expected, we found that we needed to add a little packing behind some of the bolt holes in the bearings, so that when the bearings are bolted up tight the shaft can still rotate. On one side a washer was the perfect size, on the other Paul cut out a small piece of sheet steel and shaped it to fit. We now know that when we come to fit the brake weighshaft permanently, it should be straightforward.
C2-800-1194v2.jpg
Loco brake weighshaft and crank now trial assembled, seen here from the fireman's side.
After removing the weighshaft, Paul dived under the chassis and put some primer on the exposed metal surface. Dave 1 applied paint the following day.
With the rack of shelves finished and immediately loaded up with completed brakegear components (creating more space on the floor), Dave 2 turned his attention to the cab floor plates. Since we are reducing the width of the cab, we won't reuse the existing cab floor plates. However, they have welded to them the bearings for the blowdown valve levers and the draincock pedal. In fact, the draincock levers were still attached too. Dave cut the bearings off the floor plate, and has started to dismantle and clean the levers. One is seized in its bearing, so that will require extra attention in due course.
The assembly drawing of the coupling and connecting rods which Erle has been working on is starting to pay dividends. The Chinese redesigned the rods to accept roller bearings. We have the assembly drawings the Chinese prepared, and Chinese drawings of many of the bearing covers and crank pin end caps. It would be logical to think that if we returned everything to 'as drawn' condition, it would all fit nicely. But working on the C2 is never that simple.
C2-800-1191v2.jpg
Dave and Erle study a print-out of the coupling rod assembly drawing.
Erle's drawing shows very little (less than 5 mm) clearance between the Axle 1 crank pin end cap and the back of the crosshead. This is insufficient to accommodate axlebox movements and wear. But when Dave 1 measured the crank pin end cap, he found it was not made to drawing, being significantly thinner.
We had noticed that most of the coupling rod roller bearing rear covers are a smaller diameter than the Chinese drawings show, and don't have a nice tapered edge. We suspected that this was just to make the manufacture a bit simpler, but Erle's drawing has shown the real reason. The full diameter rear covers would foul on the inside edge of the tyre.
Clearly, in both the above cases, the Chinese have found problems with their original design, and have further modified the design to eliminate them. But they haven't updated the drawings!
With corrected crank pin end caps drawn, and using measured coupling rod geometry (some are not quite straight), Erle and Dave 1 tried to fit the coupling rods on the computer model, using the roller bearing covers to position the rods, just as would be the case in reality. It looks as though, if we make small adjustments to the dimensions of the roller bearing covers at each crank pin, we should be able to get everything to fit together with the required clearances. Well... almost.
The lateral clearances between the crank pin end caps and the roller bearing covers at Axles I and IV (the end axles) are stated to be +/- 0.5 mm on the Chinese assembly drawing. But the measurements of the actual components show that the clearance obtained will be +/- 1.25 mm, a lot bigger! To be honest, we thought that +/- 0.5 mm seemed to be exceptionally tight, given how much relative lateral movement of the wheelsets is likely. Once again, it looks like the Chinese have found that a bigger clearance is necessary and have made the components accordingly, but not updated the drawing.
Although sitting in front of a computer screen doing drawings doesn't appear to be progressing the job in the same was that cutting bits of metal does, it is an exceedingly worthwhile exercise. We would really be cursing if we'd made components to the Chinese drawings, then found they didn't fit. Much better to find out on a computer screen first.
C2-800-1196v2.jpg
Erle in the design office. This is usually Paul's job but he's spent too much time looking at a laptop recently so was very glad to do some practical work for a change. Erle is doing a marvellous job with the coupling rod assembly drawings.
A little more thought is required before we can finalise the coupling rod assembly drawing, so Erle has started to measure and draw up other parts of the motion. The return cranks fit onto the ends of the driving crank pins, and so have an influence on the roller bearing covers. As expected, the Chinese have modified the design a little to accept roller bearings, so it is essential to draw up what we actually have.
We hope we are not too far off getting the cylinders rebored and fitted, so thoughts are turning to the components which attach to the cylinders. First in line are the draincocks and their operating mechanism.
Ed dismantled and cleaned the four draincocks. One was seized, but came free with a little encouragement from a hammer. Fortunately, after cleaning, all four draincocks look to be in good condition. After cleaning with a wire wheel, Ed sprayed them with wax to protect them against corrosion.
C2-800-1190v2.jpg
Cylinder draincocks now dismantled and cleaned. We'll lap the valves in and then re-use them.
Mounted on each cylinder is a short weighshaft to convert vertical motion from the draincock dropper links to horizontal motion of the valve cam rod. Ed managed to dismantle one of them by drilling the shaft out of the crank at one end. We want to keep the cranks, as they are castings which would be difficult to replace. The shaft itself is bent, and so is in need of replacing. The other weighshaft assembly is seized, and also appears bent, so is currently soaking in diesel oil. It will be the focus of our attentions at a future working party.
The main draincock weighshaft extends from side to side of the engine. Because we have narrowed the frames, we need to shorten this weighshaft. Dave 2 removed the cranks without too much trouble (the pins holing them on weren't damaged like the ones Ed had to deal with), and he cleaned them up. We'll make a new, shorter weighshaft, but, again, the cranks are to be kept.
Finally, Dave 1 started to clean up one of the draincock dropper links. It is made from tube, which has got a little bent. It may be possible to straighten the link, or we may replace the tube. The fork on the end will definitely be reused though.
Paul has been doing a lot of homework on the archives recently, including buying and translating many old Chinese books about narrow-gauge railways and the industries that used them. Back in 2007 some of the C2 Project Group members visited the Weiyuan Coal Railway at Huangjinggou, Sichuan Province. We saw one of the last coal trans before the line closed. Paul has now acquired the history book of this mine and railway, and found a few photos of the line in its heyday. Here's a contrasting pair of photos.
C2-800-1198v2.jpg
A coal train hauled by a Shijiazhuang-built 28t loco (equivalent to a C2) crosses the high curved viaduct on the Weiyuan Coal Railway on 2nd April 2007, not long before the line closed.
C2-800-1199v2.jpg
On the same viaduct but many years earlier, a similar loco hauls a mixed train including nine passenger coaches, two open wagons and a string of coal wagons.
We'll be back at Boston Lodge again in about 10 days, with a bigger group and plenty more to be getting on with.
C2-800-1202v2.jpg
Seen at Huangjinggou in 2007 is one of the last surviving passenger carriages, loaded with rocks! The loco and track had seen better days too.
Late January 2019