The work required to convert No. 4942 back to a Saint Class 4-6-0 is now under way. Three new driving wheelsets and two bogie wheels have been manufactured and the first stage of the rebuild the alterations to the main frame has now been completed.
Before starting a full examination of the donor frames, which included an ultrasonic test, was undertaken which confirmed that these were still sound, although some cracks were found above certain hornguides which required the previous weld to be removed and new weld applied rather like a visit to the dentist for a filling repair! The rear section of the mainframe under the cab on the fireman's side also displayed some wasting where the fireman's hose had caused corrosion. Here there were two alternatives, we could either build up the existing plate work with new weld or cut out the wasted area and weld in new steel plate the decision was taken to follow the latter option.
The first job tackled has been the reduction in height of the main frames by 4.25in, which has been achieved by shaving off the top of the main frame. Saint frames were notorious for not being as strong as would be liked and since the area above the driving wheels will be hidden by the splashers, it has been decided to retain the 4.25in above the horns for the leading and centre driving wheels to retain as much strength as possible. The frame over the rear driving wheel has been reduced to the same height as the rest of the frame.
At the rear a new drag box has been fabricated and fitted. The old drag box was also badly corroded and would have required replacement in any event. Provision is also being made at the rear of the main frame for fitting the horn guides and strengthening plate for when No. 2999 runs as an Atlantic. The four horn guide castings are currently on order and are expected to be delivered very shortly. To put it mildly they are big beasts, some 2ft long and weighing in at around 100 kilogrammes a piece the pattern for these was made by Ken Gibbs during the summer of 2003.
The next job to be tackled is the front extension frames, which need to be machined ready to be fitted to the main frame. This is quite a big job, which will be followed by the modification of the buffer beam from No. 4942 prior to the latter being riveted to the extension frame. The buffer beam has been dismantled at Didcot during the summer and is now being made ready for fitting.
When the extension frames are complete it is the intention to fit the new cylinder block to the frames. The two cylinder blocks will need to be attached to one another before they can be fitted which involves the manufacture of 24 stays of various lengths. Once these have been joined together, the cylinder blocks can be assembled as part of the frame assembly, which will also be optically aligned at the same time as part of that exercise.
Since autumn 2003 the two new extension frames have been fully machined and are now ready to receive the new cylinder block and buffer beam assembly. The two strengthening plates to allow the locomotive to run as an Atlantic as well as a 4-6-0 have also been fabricated ready to receive the hornguides once this has been completed it will be stored until we are ready to run the locomotive as an Atlantic in due course. The new cab sides have also now been fabricated.
Everything is now ready to assemble the whole frame structure in reality the most testing part of the whole exercise. The bogie centre pin from No. 4942’s cylinder block has been fitted to the new cylinder block and the latter is now ready to be attached to the new extension frames. These in turn can then be riveted to the rebuilt main frame. At the same time the buffer beam assembly will also be attached ahead of the new extension frames. As part of this exercise the cylinders will be optically aligned to the complete frame thus ensuring final accuracy of the complete rebuild.
In the meantime the new cab and roof assembly has been completed, the new footplate support brackets which are different from the ‘Hall’ design have been manufactured and work is underway on the new footplate, all of which can be fitted once the frames have been assembled. Work has still to start on the new splashers which will be to the original Churchward riveted design although the materials are to hand and have been profiled to shape. All the springs for the driving wheels and bogie have now been refurbished and the driving wheel axleboxes are being made ready to receive the new wheelsets to complete the rolling chassis.
Meanwhile at Didcot work on reassembling the bogie has begun. As the bogie axlebox keeps were missing when we purchased 4942, replacements have now been cast and the remetalling of the axleboxes to suit the new wheelsets is underway. New fitted bolts to complete the assembly of the bogie frame will also be manufactured shortly.
Work on the frames continues at Bury. Starting at the front the original buffer beam assembly from No. 4942 has been rebuilt. The beam itself has been reprofiled along its lower edge to the Saint type and the support angles behind that were severely corroded have been rebuilt and re-riveted. The new cylinders have been bolted together and secured to the new forged extension frames. A new cross member (or frame stretcher) has been fabricated and fitted under the cylinders between the extension frames; also the new cross member behind the cylinders,through which the valve rocking levers pass and which is quite different from the Hall type, has been made and fitted. The bogie side control ball castings from No. 4942 have been fitted to the new extension frames.
So the whole cylinder, extension frame and front bufferbeam arrangement has been completed as a sub-assembly and at the time of writing in early November staff from the Severn Valley Railway have just completed the final alignment of the complete frame assembly using their optical alignment equipment. The extension frames can now be secured to the main frames in their final position with fitted bolts. Most of the footplating is complete except for the sections adjacent to the cylinders which, although made, await the final alignment of the frames in case any minor adjustments are necessary. We have used much of the original footplate angle from No. 4942 but all the platework is new.
The platework in front of the cab which carries the rear splashers has been made to be easily removable so that a plain piece of plate without a splasher can be substituted for the Atlantic conversion. The splashers have faithfully followed all the riveted construction of the original design and have been fitted to the footplate and mainframes. They await fitting of the brass beading which again is of a different design from the normal Collett style. We have made a pattern for the beading and an order has been placed, initially for just one so that we can evaluate it before ordering the remainder. The cab assembly is complete except for the fitting of the tubular brass edge beading and is bolted in place on the frames, and is complete with the front spectacle and porthole window frames.
The distinctive slotted cab step assemblies have been finished and fitted. The rear extension frames for the Atlantic trailing wheelset have been successfully trial fitted to the mainframes to ensure a satisfactory fit. The newly cast Atlantic trailing wheel axlebox horns have also been machined and currently await fitting to the extension frames. The rear drawbars from No. 4942 will be reused and new intermediate rubber pads and associated steel discs have been sent to Bury from the Didcot stores in readiness for fitting.
With the frame alignment now completed we can progress to assembling the new driving wheelsets to the frames. New spring hanger bolts are being made as the ones from No. 4942 were past their ‘sell-by date’ and we have also sent from Didcot the new rubber pads and steel discs fitted to the spring hanger bolts which form part of the locomotive’s suspension, to put it in automotive terms. The driving wheel springs from No.4942 have already been reconditioned and are at Bury ready to be fitted. The existing driving wheel axleboxes from No. 4942 are being fully overhauled prior to refitting. Meanwhile members of the North Western Group continue with the filling and painting of the driving wheel sets, all having now received two coats of undercoat with topcoat black to follow.
At Didcot the group led by Martin Breakspear continues with the overhaul of the bogie and new tubular stretchers have been made and fitted. The horn guides have been trued up and Peter Gransden has made a start on overhauling the axleboxes off No. 4942, with the first axlebox presently having the whitemetal bearing surfaces machined to suit the new bogie axles. The bogie wheelsets are new and have Churchward design wheels although it is difficult to tell the difference from a Collett bogie wheel.
We are hoping that, because the journal size of the axles from No. 4942 is smaller (having been machined several times during successive overhauls) than on the new axles which are at nominal size, providing the existing white metal is sound we shall be able to get away with just machining to the new dimensions without having to remetal as well. The newly cast axlebox keeps are also being machined at present. The forty odd new bolts needed to reassemble the bogie frame are being manufactured at present so final re-assembly should begin shortly. Meanwhile painting of the various parts is in progress. The Didcot group was planning a visit to Bury in early November to needle gun and paint the outer faces of the mainframes before rewheeling commences.
Meanwhile Ken Gibbs continues to make various casting patterns for the locomotive. In the past few months he has made patterns for the motion bracket, valve rocker shaft bearing, front and rear cylinder covers, driving wheel brake block and even the worksplate that is located in the middle of the square end footplating below the smokebox. None of these, or any of the other major components and modifications, would have been possible without the many drawings produced by Peter Rich and Mike Rudge.