Let’s get 4561 rolling
Having considered the options for the refurbishment of the coupled wheel axleboxes it was decided that the existing bearings and horn liner bronzes were beyond recovery and should be replaced. The unwanted 12mm holes will be plugged and sealed and the 3/8” BSW holes refurbished to allow the new liners to be fitted as originally intended.
This proposal was put to the WSRA Board for approval of the additional costs expected to be involved before placing orders for the supply of new bronze bearing castings and the liner plate materials.
Meantime the 4 crosshead slidebars have been refurbished and polished before being fitted in their respective positions on the support brackets (or ‘G’ irons) behind each cylinder. This enabled their alignment to be checked as parallel to the cylinder centre datum wires; and to ensure they are correctly spaced to determine the thicknesses of bronze packing pads to be fitted both at each ‘G’ iron and at each rear cylinder cover before being finally bolted in position.
Shown are the two RH slidebars in position parallel to the datum wire. It is just possible to see the gap between the lower bar and the cylinder cover for which a packing pad is needed. It is also just possible to see the end of the top bar has been stamped ‘5553’ which is the locomotive no. on which this bar was first fitted by the GWR
This is another view of the RH side showing how the slide bars are supported by the ‘G’ irons to which they are bolted by the bolts recessed into each bar. The outer end of the lower bar top surface has a sloping flat machined into it to provide an adequate running clearance from the connecting rod when fitted. This is not required for the upper bar owing to the cylinder centre line being 2 ½” above the driving axle centre line.
This photo shows the LH slide bars have also been fitted. Again it is possible to see the gaps between the front of each slide bar and the rear cylinder cover lugs waiting for their respective packing plates.
Mention was made earlier about the datum wires which have been set up at each cylinder bore centre line from the front of each cylinder to behind the rear coupled axle location. In addition ground steel datum bars have been set up at each coupled axle centre line on mounting blocks carried between each pair of horn blocks. These datum bars have enabled checks to be made to ensure that the coupled axles will be located square to the frame plates at the correct distances behind the cylinder centres and from one another. They have also enabled checks to be made that the cylinder centre lines are 2 ½” above the coupled axle centres. (This is a design peculiarity of Churchward locomotives).
The design heights of the coupled axles within the horns had previously been stamped on each frame plate during assembly. In the photo. above the square has been mounted at a datum point (circled in chalk) to enable the cylinder centre line height to be confirmed.
With confirmation that all key dimensions have been achieved the remaining fitted bolt holes can be reamed and the bolts made and fitted. The datum wires and bars will remain in position as a basis for horn cheek grinding to designed sizes and the subsequent machining and fitting of the 6 coupled axleboxes.
As a next step a start has been made on making up the new cladding sheets for the cylinders. The photo. shows the main wrapper plate on the LH cylinder cut to size and shaped to fit the cylinder casting held in place with setbolts screwed into the front and back flanges. Ultimately this plate will encase the cylinder insulation when fitted.
Work has started on preparing the axleboxes for further use. They had bronze liner plates screwed to each horn face which were fitted to make up for past wear and tear. These in turn have become badly worn and require to be replaced. In the example shown the liner has been removed and revealed that apart from the stubs of the fixing screws yet to be removed there is also another set of unused screw holes. These are the correct 3/8” BSW thread form whereas the screws used appear to have a 12 mm Metric thread. A common standard will be adopted for the fitting of the 6 new sets of liners.
Efforts have been concentrated on completing the assembly of the front frame components which have been riveted in place with the exception of the curved section of the RH running plate support angle (see first photo. on 29 March top centre). On assembly it was found that the top corner had been modified at some time, presumably as the result of damage, and was lower than the transverse angle member across the front of the saddle. This can just be made out in the following 2 photos.
This support angle will be corrected before being finally fitted in place. As can also be seen, the opportunity has also been taken of fitting the two braces between the underside of the smokebox and the buffer beam. These reinforce the front frame’s ability to withstand and heavy shunting impacts.
This view shows all the frame members in front of the new cylinders duly riveted in place including the front pony truck support member in the centre and shows the diagonal braces more clearly. The cylinder block and smokebox saddle have been given a coat of grey primer while the remander is being painted black.
This view of the LH front shows clearly how many rivets there are in the front buffer beam now that it is finally riveted in place.
Apart from the frame members other parts are being refurbished and/or machined ready to be fitted in place. These include :
The fulcrum block freshly painted. This was sent to contractors to weld up the badly worn bolt holes before they could be re-drilled ready for fitting.
This shows the fulcrum block fitted to the underside of the horizontal frame stretcher between the cylinders. In this position it provides support for the spring compensating beam to be fitted in due course between the pony truck and leading coupled axle.
Both rear cylinder covers have been machined and painted. The RH is shown. The central hole is for the piston rod and gland packing. The other hole is for the cylinder safety valve. Particular care was taken with cutting the screw thread in this hole to ensure the valve fitted snugly.
This shows the RH cover fitted to the cylinder with part of the safety valve fitted. Also a datum wire has been set up through the cylinder bore. This enables a check to be made that the cylinder is in line with the locomotive longitudinal centre line, parallel to it; and the correct distance from it and the adjacent frame plate.
This shows how the matching datum wire is anchored at the front of the LH cylinder. It is stretched tight enough that accurate measurements can be taken from it when fitting the slide bars, crosshead and connecting rod when the 4561 is re-wheeled. It also enables a check to be made that the centre line is horizontal and 2 ½” above the coupled wheel axle centres. This was a needed on Churchward locomotives to ensure the large cylinders were within the loading gauge
Finally the 10 axleboxes have been recovered from storage and are being thoroughly cleaned ready to assess their condition and decide what work is needed to make them fit for service.
More funds are still needed to get this loco back on the west somerset rails. Please donate what you can.
Front footplate brackets and angles recovered from the old frames have been prepared ready to be fitted to the new behind the front buffer beam. Included are the front footsteps.
Fitting of the brake and spring gear is being progressed. This is a check fitting of a brake hanger and cross beam (below frame plate) to check that all parts are available. Either side of the hanger firmly bolted to the frame plate are the ‘J’ brackets (light green) from which the coupled wheel springs will be suspended in due course.
Safety chains are to be fitted to the brake beams in case of breakage in service for which the bolts are being made.
When the extension frames were assembled some fitted bolts and nuts were omitted from the front pony truck pivot. The remaining 6 bolts and nuts have now been made.
Items are gradually being fitted to the leading buffer beam now it is in place. The rectangular hole needed in the centre for the front coupling has been finished to size and the coupling hook inserted. Hung in the hook is part of the screw coupling linkage which is being refurbished. The pipe flange alongside is the leading end of 4561’s steam train heating pipe to be. The small item next to the buffer is part of the bracket on which the leading vacuum brake hose is to be secured when 4561 is hauling a train in traffic.
With the main horn block sets in place in each frame plate it is critical that the gaps between each pair are finished to known sizes to ensure the correct tolerances when the axleboxes are fitted. Not only must they be a known distance apart but in line across and square to the frames; and in line along each side parallel to the locomotive’s centre line. The horn faces are ground to final sizes to ensure they are smooth, flat and parallel.
For this work the workshop team has developed the multi-fit horn guide grinding machine seen in the photograph mounted between a pair of horn blocks and in use to grind their respective faces. The machine’s capabilities have been checked and confirmed to give good results on some other locomotive work that Williton Works has been involved with.
Steady progress is being maintained on the frames with the front buffer beam (now fully drilled) bolted into position and the buffers fitted having been overhauled. These mask the work done on completing the fitting of the front dragbox and the leading pony truck centre. Yet to be done to the buffer beam are drilling the hole for the front steam heat train pipe and completion of the cutting of the rectangular hole in the centre ready for fitting the front coupling hook.
To reinforce the ends of the buffer beam outside the frames, brackets are fitted between this and each main frame plate. These were on hand but have been found not to comply with the design drawings so are being replaced with correct versions, thanks to Bob Meanley being able to provide a copy of the appropriate drawing.
The incorrect buffer beam brackets awaiting their fate.