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Sir Nigel Gresley overhaul – update 13

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The team in The Works are pressing on with the overhaul of Sir Nigel Gresley. Locomotive Engineer Darrin Crone provides us with an insight of recent weeks’ work.

This is the 13th update – you can catch up on the previous posts here.


Week commencing 3 February

All the footplate rivet holes have now been repaired and are ready for new rivets to be fitted, except one. The one outstanding hole is in the corner of a bracket which, though detailed as riveted on the LNER drawing, is impossible to get a rivet of sufficient length in. The hole had a bolt in it welded to the footplate which was clearly not original. So it’s a mystery how the LNER did it. The repaired holes have been drilled and countersunk back to the size detailed on the original LNER drawings.

We are now ready to fit new bolts to the dragbox and new nuts to the existing bolts. Suitable washers to match the full-size Whitworth nuts were finally delivered this week, too late to be fitted. In preparation, the top of the dragbox was cleaned and the needlegun used to remove scale from around where the new nuts will be fitted.

Painting continues with the frames in front of the cylinders on the outside being primed. The Paint Team have also painted the front bufferbeam. The front coupling hook housing was removed again this week and was painted. The housing shows wear, which is to be expected. This will have to be measured to examine if the wear is acceptable or requires repair.

The front bufferbeam was primed this week.

The front bufferbeam was primed this week.

The inner sleeves of the front buffers are now being examined and refurbished to remove the decades of wear they show. The first one was put in the lathe to check for straightness and its front section was carefully skimmed to remove surface marks and impact damage.

The inner left-hand buffer sleeve in the 1946 vintage Holbrook Model B No. 21 lathe, in the National Railway Museum workshop. The wear to the front of the sleeve that projects from the buffer housing can be seen.

The inner left-hand buffer sleeve in the 1946 vintage Holbrook Model B No. 21 lathe, in the National Railway Museum workshop. The wear to the front of the sleeve that projects from the buffer housing can be seen.

The exhaust silencer for the air pump was inspected then primed this week. The drain valve on the bottom of the silencer was stripped, cleaned out and examined. On the subject of examination, 5 of the 6 coupled wheel horn castings were inspected. The painters will be pleased to know that these can now receive their attention.

The horn castings were examined for cracks this week. The top corners are areas likely to be affected by fatigue cracks. The casting surfaces are rough and careful inspection is required. Inspections are always carried out by two people to ensure nothing is missed. This is the right leading horn casting viewed from inside the frames.

The horn castings were examined for cracks this week. The top corners are areas likely to be affected by fatigue cracks. The casting surfaces are rough and careful inspection is required. Inspections are always carried out by two people to ensure nothing is missed. This is the right leading horn casting viewed from inside the frames.

The splasher bracket rivet holes in the frames were finished and countersunk with a special tool made by the Engineering Team. It worked very well and the finish of the holes is now suitable for the fitting of countersunk rivets. The rivets will have larger-than-normal countersunk heads so have to be specially made. The longer rivets for the brackets, which are attached to the double frames, were made on Saturday.

The outside of the front section of frames have been inspected and receive a last prep by Alan Pitt before painting.

The outside of the front section of frames have been inspected and receive a last prep by Alan Pitt before painting.

The middle cylinder cover holes received a final clean out this week, now that all the studs have been removed. They have all been inspected and are in good enough condition for new studs to be fitted.

The frames in front of the cylinders are primed.

The frames in front of the cylinders are primed.

The overhaul of the air pump began this week, after extensive cleaning over previous weeks. Engineering Team volunteers have done a great job in information gathering and we have photographs from the last overhaul. This week it was decided that we must first find a spot in the workshop where we can dismantle the pump and lay out its parts without them being disturbed, so an area was identified and agreed with the workshop management. The area will be cleared and the air pump moved.

Bob Shearman has fitted new gaskets to the steam sandbox top flanges. The filler pipes with new packings are being refitted. The left-hand pipe was refitted this week.

Bob Shearman has fitted new gaskets to the steam sandbox top flanges. The filler pipes with new packings are being refitted. The left-hand pipe was refitted this week.

Week commencing 10 February

The right-hand buffer sleeve put in the lathe last week has now been finished. With an impressive result, the left-hand sleeve was similarly treated. The surface skimming also involved restoring the internal radii that matches the back of the buffer head. After taking a couple of photos, the ends have been taped up to protect them until they are refitted to the loco. We must thank Dan Holmes of the National Railway Museum for allowing us to put the sleeves on his treasured Holbrook lathe and operating the hydraulic copier to ensure accurate machining of the end radii. The buffer housings have backing plates that are screwed onto the housings. The threads on the housings have either been re-tapped oversize or have broken screws in the holes. This week the repair of the holes was started, with the welding up of the oversize holes so they can be re-drilled and tapped.

The buffers with the reconditioned buffer sleeves.

The buffers with the reconditioned buffer sleeves.

The refitting of the steam sands filler pipes was completed this week. Like many parts around the engine, they have been examined and repainted off the loco. Particular care was taken to ensure that water can’t get into the sandboxes, so new seals and packings have been fitted. Fitting also ensured that there is clearance around the pipes where they go through the frames to ensure no chafing in traffic. Very elegant they look, too; much better than on another Gresley Pacific we have recently shared workshop space with, which has angular looking fabricated pipes.

The right-hand steam sands filler pipe has been refitted.

The right-hand steam sands filler pipe has been refitted.

The air pump overhaul began in earnest this week with the air pump being moved on to a bench where dismantling and examination began. Preliminary examination shows little apparent wear to the cylinder bores, but it is early days yet.

The top of the air pump. Normally mounted vertically, it is laid horizontally on the bench for dismantling. The lubricator is normally mounted on the top cover and has been removed in the photo.

The top of the air pump. Normally mounted vertically, it is laid horizontally on the bench for dismantling. The lubricator is normally mounted on the top cover and has been removed in the photo.

The countersunk rivets – for which we need to finish the riveting of the splasher frame brackets – were made this week. The long ones for the double frames were machined last week.

The top cover removed. This is on the top end of the steam cylinder where the mechanism is located that directs steam to either side of the steam piston. Some of the components for this mechanism are laid out.

The top cover removed. This is on the top end of the steam cylinder where the mechanism is located that directs steam to either side of the steam piston. Some of the components for this mechanism are laid out.

The saddle casting was signed off last week by our Chief Mechanical Engineer (CME), subject to some minor repair work. This allowed the painting team to work on it. After a brief visit by the needle gun a coat of high-temperature silver was applied. The rear flange of the saddle has been left unpainted as there are numerous holes from fastening down the smokebox, not all used, so they will be welded up and re-drilled after the refitting of the boiler.

The air pump lubricator removed from the air pump. The lubricator comprises three pumps. One pumps steam oil to the steam cylinder, air oil to the air compressor cylinders and to the piston rod glands.

The air pump lubricator removed from the air pump. The lubricator comprises three pumps. One pumps steam oil to the steam cylinder, air oil to the air compressor cylinders and to the piston rod glands.

Meanwhile in the dragbox, descaling has continued. Originally planned to be a final descale around the existing bolts to ensure a good base for the fitting of new nuts, the results have been so good that it has been extended to the entire dragbox casting. It is worth doing as the cleaner we can get it and then get it painted the longer it will last. The good surface finish will also now allow a more reliable di-pen examination.

The horn castings have now all been examined and di-pen tested with the last one completed on Tuesday. The painting team were straight on to the castings and they have now all been primed. Painting continued between the frames this week. On Saturday the repaired leading right hornstay returned to York and was refitted by our junior volunteers, the ‘007 Gang’, under the guidance of our CME. With this refitted, the leading left was then removed for repair.

A tested hornstay casting is given a final needle gun treatment before painting.

A tested hornstay casting is given a final needle gun treatment before painting.

Written by Sam Terrace

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  1. Mr G Silkstone

    Just imagine in the days of steam the amount of work which went into the maintenance of locomotives and the manpower employed in the industry.

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