The team in The Works are pressing on with the overhaul of Sir Nigel Gresley. Locomotive Engineer Darrin Crone provides us with an insight into recent weeks’ work.
This is the 16th update – you can catch up on the previous posts here.
Week commencing 5 May
The reverser clutch has been undergoing refurbishment over the last few weeks and has already received new brake linings. This week we acquired the new rubber diaphragm. To keep production costs down the diaphragms are supplied without holes, so these have to be punched through. Once this was done the clutch was reassembled and can now be refitted to the loco. A spare diaphragm was also obtained, which has been punched and will be put in store.
The clutch grips onto the reversing shaft, which was put up on trestles this week to begin the removal of paint and general cleaning prior to inspection. The end journals were inspected and are round, parallel and showing little wear. The bearings in the brackets on the loco were also inspected. They are in a satisfactory condition and will not require replacement.
The regulator valve overhaul continued this week with the valve seat lapped using a special tool brought from our Grosmont store. Danny Holmes of the National Railway Museum skimmed both the valve and pilot valve to restore their faces, with the latter showing the most wear. The pilot valve was then used to lap the pilot seat in the top of the regulator valve. Inside the valve there are rings that run in an internal bore, which was cleaned before the unit was reassembled. On the bench the travel of the valve was measured and compared to the LNER drawing. It was confirmed that the movement of the operating lever connected to the regulator lever in the cab produces the correct lift of the regulator valve. During the valve rebuild the brackets that support the valve in the boiler and the operating half shafts were dye penetrant inspected and no defects were found. New bolting is required to complete the regulator valve overhaul and it will then be refitted to the boiler.
Painting continued on the inside of the loco frames, behind the buffer beam and on the bogie. The cylinder ends received their first coats of high temperature black and by the end of the week the bogie was receiving undercoat. Before painting began on the top of the bogie, Alan Pitt dye pen inspected the welds around the sections added to the bogie centre casting and to an old weld repair. No faults were found.
The bogie centre casting that sits between the bogie stretcher on the loco and the centre casting in the bogie frames received dye penetrant inspection this week. There is more to do on this part and it will need a comprehensive dimensional inspection to determine why it shows uneven wear. Our CME completed his dimension inspection of the bogie frames this week.
The top of the bogie centre casting that slides from side to side in the bogie. The loco pivot pin goes down the centre hole.
The position of the refurbished combined spring and brake shaft bracket was confirmed on Tuesday before new fixing holes were drilled through. After last week’s disappointment with the breaking of the cutter on the first hole, it was not without trepidation that the mag drill was started and the cutter entered its first hole. However, the drilling went well and the same cutter managed to drill all the fitted bolt holes. In addition to the bolt holes, two smaller rivet holes were drilled through in stages using standard drills. Four of the old fitted bolts were machined as clearance bolts and have been used to clamp the bracket in place. The bolt holes will need reaming and new bolts making, but first the back of the bracket will require countersinking for the rivets and spotfacing for bolting where the holes are near to the welds.
The holes for the mounting of the leading right-hand combined brake shaft and spring bracket were drilled through this week. Malcolm Bateman supervises as John Livesey feeds in the cutter.
The two loco brake shafts were moved to near the bogie for inspection and refurbishment. While taking the paint off the trailing shaft we discovered that it is marked 4901. There was an A4 numbered 4901, named Capercaillie, which became BR 60005 Sir Charles Newton.
The loco brake shafts are now being refurbished. The trailing shaft has the long arm laying on top of the leading shaft.
The long arm on the trailing shaft is marked 4901.
Reinstalling pipework between the frames continued this week with the refitting of the couplings that connect the axle box lubrication hard pipes to the hoses joined to the coupled wheel axle box underkeeps. The steam sands supply pipe was cleaned, annealed and refitted between the tee on the stretcher between the sand boxes and the Cartazzi frames. The pipes to the vacuum clutch and the last remaining copper pipe for the axle box lubrication system were also retrieved from store this week. Cleaning and annealing of these pipes began.
The boring of the cylinder mounting holes continued, but as the job gets harder the progress slows. After a number of modifications to the jig, the last and most inaccessible hole has been bored through. Before work stopped last Thursday, the last finishing cut was just short of breaking through.
We are planning to remove the accommodation bogie and support the front of the loco frames on our new screw jacks. This will enable the loco bogie stretcher and lower outside cylinder bolts and studs to be examined. To use the jacks we need a beam for them to stand on, since we are over a pit and the distance over the frames is within rail gauge.
The screw jacks under the front of the loco frames will take the weight of the frames when the accommodation bogie is removed.
We were given surplus steel beam by Simon Holroyd and two lengths were cut to size. Some steel packing was required to make them level with the rail head and this was cut to size before the assembly was welded together. After grinding to ensure a good fit between the rails, the beam assembly was lowered into position with the crane. The jacks were then put in position ready for the lift. The bogie pivot pin was also removed so that the frames don’t have to be lifted so high to clear the accommodation bogie.
The bogie pivot pin was removed this week. The nut is at the lower end of the pin.
The valve chests that require new liners have now been measured by the supplier and the liners will now be finish machined. When they are finished, fitting will be organised.
Not mentioned in the report, but a special new thread stud had to be manufactured for the manifold. This is shown fitted in the centre top hole. The manifold shut-off valve has been repacked and the overhaul of this assembly is now complete.
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