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By Darrin Crone on

Sir Nigel Gresley overhaul – update 43

Welding. painting and snagging are the order of the day as the restoration steams through the summer.

Weeks commencing 12 and 19 August

With the tender axlebox bearings all now ready for fitting, the tender frames are ready to be lowered on to the axleboxes and wheelsets. The tender axlebox rubber seals that seal against the wheels have now all been fitted and the only outstanding piping job—the lagging of the steam heat—has now been completed.

The 2:1 lever on the marking out table
The 2:1 lever mentioned in the previous report on the marking out table

We are in discussion with suppliers for the hire of the necessary equipment but so far they have been unable to give us a date to collect from their depot. After the frames are on the wheels there will inevitably be some de-snagging then the tank will be refitted. Fasteners for the tank are on order.

The plan for the tender frames and tank lift is being developed and the risk assessment is at draft stage, being circulated amongst the Risk Assessment team.

During the assessment and test of the leading tender dragbox it was decided that the material thickness around the safety link holes should be rebuilt. This is best done before the refitting of the tender tank so we have now had a contract welder in to do the work. To minimise the amount of time the welder has to spend on site we ground round the areas to prepare it for welding.

While on site, the welder also repaired the valve chest cover that was found to be cracked during its examination.

The leading tender dragbox receives overlay welding
The leading tender dragbox has received some overlay welding to restore material thickness to the safety ink holes

Meanwhile the tender brake and suspension components have been painted. These components being easier to fit to the tender frames before the fitting of the tank. The tender springs were mounted on the tender frames and then the spring hangers put up.

The tender frames have now been painted to gloss and varnished. The last patches under the tender tank, inaccessible until the front end beam was moved for the fitting of the vacuum brake cylinders, has also been painted to top coat.

At the front of the tender tank the flanges wasted away that connected the front plate to the tank in the coal space have been drilled and are being welded in place. The front plates are being bolted to these flanges. The last corridor roof section has now been fitted and trimmed to meet the back of the front plate. This was not easy as the existing corridor slopes down toward the cab end. Good alignment has been achieved with the existing lower section of the corridor.

The wooden template for the top section has been refitted and aligns very well with the new corridor roof.

Also on the front plate, the cutout where the scoop indicator pipe comes through was drilled and tapped so the indicator and cover plates can be refitted.

On the outside of the corridor the mammoth grinding job of removing the streamlining weld that ran the length of the tender to the water filler space bulkhead has been completed. The burring out the holes along the tender tank rear flange that were welded up to reduce their size to specification has also been completed.

Meanwhile welded patches have also been put in behind the corroded and holed plates around the tank left hand top beading.

At the back of the tender, the vestibule handrail has been finished and it has now received a coat of primer. Looks like new. At the bottom of the vestibule work continued plugging bitumen leaks.

Work on the ‘cod’s mouth’ gear continues with new bronze bushes being made for the horizontal shaft. Some final fitting is required. There is some damage to threads and other minor components which is being worked through.

The middle slidebar bolts are now completed and ready for fitting. All the others are drilled for feather key fitting, with some now done. It has been decided that one further existing bolt should be replaced. A new bolt has now been roughed out.

The pinning of the outside valve gear continues with all the outside pins now fitted. The pins that require locating with taper pins are now being drilled or notched and reamed for pins. A new bronze bush has been made for one of the combination levers and this has been pressed in. The dimensions of the taper pin holes have been measured and the size of the taper pins and reamers we need has been calculated. eBay is now being monitored and one taper reamer already snapped up at a bargain price.

A radius rod
One of the radius rods with a motion pin fitted is drilled through for fitting the taper pins that locate the motion pin in the rod

The middle big end bronze castings have now been received and a draft drawing produced of the finished bearing. The gluts that form part of the clamping of the bearing have been surface ground and are being fitted to the big end strap. The machining and metalling, to a procedure specified by us, is now being discussed with a contractor.

The RH eccentric, now part machined was brought in this week as we were concerned that the existing dimensions were not corresponding to the drawing being worked to.

One of the eccentric rods on the marking out table
One of the eccentric rods on the marking out table being carefully measured so that the specified clearances from the return cranks can be calculated

The old RH crankpin square was also retrieved and measured. It was found to be short, which corresponded to the eccentric being thinner than drawing. Only by a very small amount and not impacting significantly on the components strength.

Attention then turned to the specified clearance between the eccentric and the eccentric rod, as the rod sweeps over the eccentric. This clearance is specified on the LNER drawing, and also noted in a BR(E) standing order issued to sheds during the 1950s.

So the eccentric rods were measured and compared to drawings. As our crankpins are new the end squares are full length and with adequate clearances measurable it was decided to add material to the outer face of the eccentric regaining some of the specified thickness. This eccentric is now at subcontractors for rebuilding with weld.

Grinding a return crank
One of the return cranks being ground after machining

The piping team have been tidying up the tender frames piping as described above, with lagging and clipping, as they will soon have their access much reduced by the fitting of the wheels and tank. They have also requested new bolting for the trailing steam heat flange, this is now on order. Fittings are also being assembled so the steam heat pipework can be pressure tested.

Part of their last activities in the tender frames is the recording of the pipe systems and what new and existing material has been used.

Work also continues on the loco lubrication pipework to the outside slidebars and glands, and to and from the atomisers.

At Llangollen, under the close monitoring of our representative, the superheater elements are being expanded. A number of expanders were sent over from our collection and some borrowed. One difficulty was accessing the end rows. These are accessed through threaded holes sealed by plugs on the top of the superheater.

Fitting the superheater elements
The superheater elements are now being fitted to the boiler at Llangollen

During the refurbishment of the header these holes, requiring repair were welded up and remade to the original dimensions. This would allow the holes to be re-threaded to a larger diameter during future repairs. However, this also meant that expanding the elements below has been made more difficult to access. An extended expander has now been obtained and is now being used.


This is the 42nd update—you can read all the previous instalments here.

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