Manufactured by Howco Ltd of Ayrshire, Scotland, the complex monobloc incorporates refinements to Sir Nigel Gresley’s original design by the Trust’s former Engineering Director, David Elliott, including improved clearance volumes and reduced heat transfer between inlet and exhaust steam. Sadly, David passed away in late 2023 and did not live to see this achievement, making the successful installation a fitting tribute to his engineering talent and contribution to the project.

Weighing in excess of 6 tons, the monobloc lift was the first major task for the newly installed overhead crane at Darlington Locomotive Works, with supporters able to witness the final stages of the operation. The assembly is currently being checked for alignment before being permanently secured within the frames.

Once the cylinder block had been lowered into the frames, it took several days to ensure it was sitting fully home and evenly supported at all four corners. Engineers’ blue was used to identify the areas where contact was being made, allowing the team to check and adjust the fit until the block was correctly seated.

With the block now fully home, the next stage is to check the alignment of the cylinders with the frames. For an initial check, a wire was stretched from a bar fitted across the cylinder cover mountings (first image) to a frame stay at the firebox. The bar at the cylinder end was adjusted to centre the wire through the cylinder bore, while the mounting at the firebox end was moved until the wire was centred in the piston rod aperture (second image). This creates a straight reference line along the side of the locomotive, against which the cylinder alignment can be checked. The same process will now be carried out for the left-hand outside cylinder and the inside cylinder.

Buy us a pint - donations of £5 soon add up! Make a donation here.