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Sir Nigel Gresley overhaul – update 19

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Locomotive Engineer Darrin Crone provides us with an insight into recent weeks’ work on the restoration of the great locomotive.

Week commencing 7 August

The new valve liners were delivered this week to York from Multitech, and the finish is extremely good. They have now been thoroughly inspected by our Chief Mechanical Engineer, Richard Swales, who confirms that they are spot on to the drawing. We will now organise fitting.

The new valve liners for the middle and right-hand valve chest have been delivered to York from contractors this week.

The tender corridor rear window, the port hole, was removed this week, as was the cover over the top of the vestibule that covers the spring that pushes the corridor connection out. The cover was removed as part of the assessment of the tender condition around the vestibule and the water filler space. Inside the corridor further needle gunning and scraping has been carried out to remove paint and bitumastic coatings in the corners and on the floor.

Work was also carried out under the tender. Cleaning between the frames has enabled the various pipe runs and conduit to be marked and a photo survey has been carried out. Now this has been competed, a start has been made on the removal of components that will enable the areas where the tender tank meets the chassis to be viewed and inspected.

The underneath of the front of the tender is crammed with pipework and brake gear, and the process of removing this has begun. The water feed valves and associated pipework were removed. The 007 Gang of junior volunteers started separating of the water valves from the removed pipework. The water feed is taken from a sump and this is in the form of a box which can be removed. We will remove it so that its condition can be assessed and it will improve air circulation inside the tender. Most of the bolts securing the box have now been removed.

The left-hand water valve with the feed pipe from the tender sump are still connected in this photo. The valve will be separated from the pipework and will be refurbished.

The overhauled cylinder lubricator was returned to York last Saturday and was refitted to the loco this week. After fitting the lubricator, we began fitting the pipework running to the front of the loco.

The refurbished cylinder lubricator, furthest from the camera, has been refitted.

The lubricator pipework from the cylinder lubricator has been refurbished and refitted.

The gravity sandbox studs were refitted to the left side of the frames this week. To enable the sandbox to be refitted, the frames were painted to top coat gloss black on this side.

The new sandbox studs have been fitted to the frames and the frames painted. The sandbox can now be refitted.

The bogie centre casting was returned to York this week from machining at contractors. The lower bearing surfaces were polished this week by Engineering Team volunteers. Three of the screws holding the leading bearing plate had come out during machining—not surprising, as the screws are relatively short so there’s not a lot of thread holding them in. New screws were machined and fitted as patch screws. After fitting, the tops of the screws were carefully finished flat with the bearing plate. Two of the screws went across oilways in the plate, so the oilways were re-cut. The centre casting is now ready to be trial fitted to the bogie.

The lower bearing faces on the bogie centre casting have been polished and three new bearing plate securing screws have been fitted on this face, one at the bottom left of the photo and one either side of the circular oilway second from the top.

The new plates for the bogie centre casting were welded in place this week. While the welder was with us we also had some welding done to rebuild a small area of wasted plate under the cab.

Work continues around the front of the loco in refurbishing the streamlining securing holes in the footplate angle. All the streamlined screws have been retrieved from store, cleaned and die nutted. Under the centre section of streamlining is the front coupling hook extension casting. This has now been refitted.

The front coupling hook was refitted to the repainted bufferbeam by 007 Gang junior volunteer Luke Perry.

Machining began on the first fitted rivets for the spring brackets this week. The hole sizes have been taken and they have been machined to finished size on diameter but the heads and ends are yet to be machined.

The mud hole doors were finish cleaned and descaled this week. They are now ready to be taken to Llangollen for their overhaul to be completed prior to fitting to the boiler.

The leading loco vacuum cylinders were delivered to contractors this week for refurbishment work to their trunnions. There is evidence of some previous attempts to rebuild the trunnions, which will have to be removed before they can be re-sleeved to the BR drawing.

Week commencing 14 August

It is planned for the coach to go to external contractors for overhaul. We use the coach for storage, though not for loco parts which are stored elsewhere—we moved some stores back to Grosmont when we transported the axleboxes. The process continued this week when we moved a storage cupboard from the coach to the workshop and filled it with stores. There is still stuff to move and another trip to our Grosmont storage facility looks likely.

We plan to fit the valve liners next week so preparations for this have begun. We have made up some plates to allow the liners to be clamped in place. These fit over the studs in the steam chest castings. There are a number of different types as the outside cylinder stud spacing is different from the middle leading, and that is different from the middle trailing.

When the new valve liners are put in the steam chests, they will be held in place by screws passing through the clamp plates made this week.

The valve liners have an orientation, which is indicated by a groove machined in their outside edge, and this must be vertical when finally located. To assist with this, small plates have been made that point along the bottom centre line of the steam chest. In addition, a tool has been made that locates in the grooves in the liner and allows it to be rotated in to position.

To position the liners accurately, they can be turned in the steam chest by the special tool made this week. It is important that their radial position is accurately located so that the gaps in the valve rings run over the bridges between the ports and not over the port openings.

The tender sump was removed this week. A large filter box is fastened above the sump that prevents solids from entering the feedwater. The last bolts were removed from the sump and it was removed, and this also released the filter. The gasket and silicon sealant sealing the assembly has now all been scraped off.

The sump from the tender stood on end after removal this week.

The leading (gravity) left sandbox was put up this week on new studs. The sandbox came off a lot easier than it went back on, as some of the original studs came out with their nuts. To get the sandbox back on a number of studs had to be removed and all are now back in place. A start has been made on fitting the right-hand studs, but the sandbox will not be put on the loco until the new valve liners are in.

New studs for the right-hand leading sandbox have been trial fitted.

The left-hand leading sandbox in place. It’s a tight squeeze to get the sandbox in between the cylinder casting and slidebar bracket and to get the top through the hole in the footplate.

The operating mechanism for the leading sands was put up this week. A new gasket was cut for the left-hand sandbox and the fit of the pins in the mechanism is being assessed.

All the fittings from the air brake valves that will be going for contractor overhaul have been removed, and the valves are now ready for delivery to the contractors.

When the leading sandboxes are in place, the trailing bogie splashers can be fastened to the loco. This week the spalshers were stripped and inspected. As with many of the thin sectioned parts of the loco they show their age with wear and cracks. One of the splashers was cracked from wear apparently from contact with a leading sandpipe. The crack was welded up and another area of wear rebuilt and dressed. The splashers were given a final clean and have received a coat of primer.

The trailing bogie wheel splashers are fastened to the loco main frames under the leading sandboxes. They have been repaired this week and are receiving a coat of primer, applied by Engineering Team volunteer Anne-Marie Lawn.

At the rear of the loco frames the damper operating linkage bracket is secured with bolts to the frames. The bolts are wasted so it has been decided to replace them. As this area of the loco has suffered corrosion, this is easier said than done.

Further work has been carried out on routing the cylinder lubricating pipework across the middle slidebar stretcher. Further work has also been done on the airbrake pipework that goes between the ashpan and Cartazzi.

On Saturday the riveting team was assembled again and good progress was made. The remaining front brake cylinder stretcher rivets have been put in. The team then went on to put the first three rivets into the spring brackets, starting on the left side of the frames. The rivets were specially machined to fit in this location. They went in nice and tight, as demonstrated by the next rivet in the row becoming slack. This was removed and will have to be replaced.

At Llangollen progress continues with the repair of the combustion chamber platework and the completion of the removal of the sling stays. The holes in the firebox roof plate can be seen along with the leading horizontal transverse stay.

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