C2 Project News

Autumn 2019

September and October 2019

The months when we forget to do a website update are often the busiest ones, and that has been the case this time. Apologies for the lack of recent news, hopefully we can make up for it now as there are some significant developments to report.
Our September working party ran from 27th to 29th. The following weekend October 4th to 6th was the railway’s Victorian Weekend, when many of us were involved on the loco and brakesman rosters. Some of the C2 group stayed in Wales for the week between the two, while others had to go back to work in between. Once everything was put away after the Victorian Weekend, there were some homework tasks such as drawings and getting quotes for component manufacture, and before long before we were heading back to Wales again for our late October working party. That started on 23rd and ran until 27th.
Sunrise over Porthmadog, just before the Victorian Weekend. This autumn has seen some extremes of weather and there have been many other days when we have been very glad to be working indoors.
Both working parties had a strong presence of our more experienced and skilled team members, and we were able to make excellent progress on some major components.
Andrew has focused his attention on the crash beams and footsteps for the loco and tender. He completed the fabrication and has now almost finished painting them. They look very smart and will contribute to the C2 ‘character’ of the front and rear bufferbeams.
Now that we have finalised the dimensions of the rods and motion, we can complete manufacture of the coupling rod bearing covers and Andrew has also continued work on these.
Tender and loco crash beams. All these need now is a coat of special paint on the footsteps, and they will be ready to fit to the bufferbeams.
Andrew machined some more coupling rod bearing covers; these are progressing well.
Before and after pictures of turning a ring of steel into a coupling rod roller bearing cover - Andrew Nelms 28/10/2019
Dave, Paul and Andrew have also been busy with design and procurement for the fitted bolts and packer plates needed for fitting the cylinders, motion brackets and brake hanger brackets; these are now ordered. We’re also reviewing quotes for the roller bearings needed in the rods and motion.
Inspection of the motion brackets highlighted that the mounting hole spacings did not match the drawings, although the brackets did perfectly match the holes on the frames. We needed to order some new packing plates to go into this interface, so these had to match what we actually had rather than the theoretical dimensions. James spent a long time carefully measuring the hole layout and Dave 1 transferred this to the CAD drawing so we could place the order.
Two of the brake hanger brackets bolt on the front of the motion brackets, so their design was also influenced by the thickness of the packing and the motion brackets themselves. Now that this is known, Dave 2 milled the brackets to the required thickness, and turned the spigots to the correct length. It was then time to assemble all eight brackets by pressing the stainless spigot into the steel bracket; Paul made this a little easier by cooling the spigots in the freezer and warming the brackets on the heater; most of them pressed in smoothly under the hydraulic press. We had a slight problem with a couple of them where the bracket seems to have been made of some dodgy Chinese steel, and the spigot was not quite as firmly gripped in the interference fit; Robco rectified these with a very neat TIG weld on the rear face! Alan and Dave 2 then drilled holes in the end of the spigots to take the retaining split pins, and Colin cleaned and painted them. Also on the brakes, Alan machined up some more of the brake pins, and Dave 2 modified two of the brake hangers to suit the revised dimensions needed for those which hang in front of the motion brackets.
A brake hanger bracket, with the chilled spigot pressed into the bracket.
Robco did some very neat TIG welding on a couple of these to ensure the spigot was reliably secured.
Drilling the holes for the retaining split pins was most accurately done in the Bridgeport mill by Alan and Dave 2.
Brake hanger brackets now complete and in primer.
Erle has continued his sterling work on the lubricator overhaul, with two now very close to completion and the third spare is in progress. The tasks carried out recently on the driver's side lubricator included fitting the steam heating tubes with newly designed sealing nuts, fitting the lower oil strainers and sealing nuts, and the blanking plates where pumps are not needed. One of these needed a replacement stud as the existing one was damaged. The refurbished ratchet mechanisms were fitted to both lubricators with new gaskets, and torqued up. The driver's side lubricator is now oil-tight apart from the sight glass.

Erle has also been adding to his very detailed drawings of the rods and motion assembly. In particular he has added the combination levers to the drawing, which turned out to be different from the Polish design. He has also been measuring up the return cranks.
The underside of one of the lubricators showing the refurbished pumps and new blanking plates fitted. By making the blanks to the same thickness as the pump bodies, standard studs and nuts can be used.
The lubricators are steam-heated, a necessity with thick cylinder oil in the -40C temperatures of north-eastern China. It won't be so cold in Wales, but having warm oil makes it easier to pump so we are keeping the steam heating feature. This has required some new steam pipes and end fittings which Erle has made.
Erle has nearly finished two of the lubricators. Here is one of them.
Dave 2 at work machining the new reverser weighshaft.
Dave 2 took on the task of machining the new reverser weighshaft; this needed replacing because the old one was about 6” too long (an effect of re-gauging the loco). He completed one end at the September working party and the opposite end in October. There is still some finishing to do including the keyways.
The major task over both working parties has been boring the cylinders and valves on the horizontal borer. This was a tricky and time-consuming task. Dave 1 took the lead, with guidance from Martin and help from a variety of the rest of the C2 group including Colin, Andrew and Paul.
Paul has translated the Chinese overhaul specification for these cylinders, and reviewed the limits applicable to the cylinder and valve bores. As well as the design dimensions, the overhaul specification includes limits applicable to locos undergoing major overhaul, intermediate repairs, and the ultimate safety limit. Limits are applied to the bore diameter, the difference in diameter from side to side, the piston head clearance, and the parallelism and surface finish of the bores. There are also similar limits for the valve bores.
We had previously measured the cylinder and valve bores, and found that they were different diameters and were worn slightly oval and barrel-shaped. The larger diameter bore at 293.3mm was close to the maximum diameter permitted at major overhaul (295mm). The worn shape wasn’t too bad but while the cylinders were off the loco it made sense to correct them. The valve bores were in good condition but also slightly worn, and there was more material to play with.
The first stage was to bore out the larger (driver’s side) cylinder, removing the minimum amount of material to achieve a parallel bore throughout. This required very careful alignment and setup, but we were able to achieve a fully-machined bore with a diameter of 294.0mm, within the limits for major overhaul. We then bored the valve on that cylinder.
On the Driver's side cylinder we wanted to bore out as little material as possible, so it was imperative to get it perfectly aligned on the borer. This shows part of the setup process.
Dave 1 and Colin check the alignment of the cylinder on the borer. This is a large machine and it's often easier to work with 2 people.
Cylinder boring in progress
The completed bore of the driver's side cylinder.
Paul then calculated the optimum size for the fireman’s side cylinder bore. One option was to bore it out to the same size as the driver’s side, but that would have meant that the clearance to the piston head would be well out of specification, so we would need to make a new piston head. He determined that there was an optimum bore diameter of 291.0mm that would enable us to meet both the specification for the diameter difference at major overhaul, and the piston head clearance requirement. He defined a tight tolerance band to aim for.
The following month, we started machining the fireman’s side cylinder and Dave was able to achieve the optimum diameter right in the middle of the tolerance band. He also managed to get the valve bore an exact match to the driver’s side. An excellent result!
Meanwhile, Paul had started measuring up the cylinder cladding and comparing it to the Polish drawings. There are significant differences between the Chinese and Polish versions; the Chinese design is simpler but in some aspects the Polish version is better. Paul developed a design taking the best features of each and drew it up to suit the actual dimensions of our cylinders. The cladding is attached to the cylinders using M8 bolts into tapped holes in the cylinder casting. During Paul’s work it became apparent that our cylinder castings were missing several of these holes, particularly on the top and bottom flanges. It was much easier to drill and tap these while the cylinders were on the table of the horizontal borer (it would be almost impossible with them bolted to the loco) so we were glad to have discovered this in time!
Finally, all the machining on the cylinders had produced plenty of swarf, which had found its way into all the hollow ports and passageways. Paul gave the cylinders a very thorough blasting with the steam cleaner, followed by Alan using an air jet to dry them out and remove any remaining dust. We were surprised how much swarf came out during this process; hopefully there is now nothing left inside.
Paul used an angle grinder to remove some casting flash on the cylinders, prior to cleaning them.
The sun lights up the newly machined cylinder bore.
Paul steam-cleans the cylinders.
Hopefully it won't be too many years before these cylinders are filled with steam from our new boiler!
Steam-cleaning the insides of the cylinder ports and passages was a very effective way of removing the accumulated swarf.
After steam-cleaning, Alan uses an air lance to dry the cylinders and remove any remaining loose particles.
Moving the cylinders around has been a challenge so thanks to the telehandler drivers (Mike, Matt, Robco and Ian) who have helped us with that. Hopefully the next time they move out of our shed, they will be permanently attached to the loco frames!
Delivering the cylinders back into our shed was tricky, but Matt very carefully manouevred the Manitou past the obstructions...
...and posted the pallet through the doorway. It's a tight fit!
Victorian weekend: Blanche and Linda pass a freight train hauled by Taliesin, at the remote passing loop at Rhiw Goch. C2 Project members were fully employed on the locos and/or as wagon brakesmen over the weekend: on this occasion Sam was driving Blanche while Paul was driving Taliesin.
Thee are still a few preparations to complete before we finally fit the cylinders and motion brackets, including temporarily removing the suspension as the springs and equalising beams block access to the fixing bolts. We will also need to ream the holes to suit the fitted bolts. Hopefully we will complete the job over the Christmas period. We can then fit the brakes before moving on to the rods and motion. This will be a really big step forward so keep an eye out for future updates!
Paul will be giving a talk about the C2 Project to the Ffestiniog Railway Society Dee&Mersey Group in Chester on 30th October. Thanks to them for the invitation to speak. We’ve done these talks at most of the FR Society area groups over the past few years, and also have one lined up next year at the Institution of Mechanical Engineers Railway Division in Manchester.
November 2019