Construction of the cylinder block for Prince of Wales has reached a significant milestone. For the first time, the three cylinders have been placed together to check alignment, clearances and to ensure preparations are complete for welding to create the Monobloc. 

The cylinder block has been fabricated in three sections, the centre cylinder and the two outside cylinders. The mating faces have been machined to create a good fit and dowels added to control vertical and front to back movement. The assembly was strapped together so the dimensions could be measured with a Faro arm.  

The three cylinders have now been tack welded together creating the first Monobloc since the 1940s and will weigh around 5 tons when complete. As the dimensions measure up as required, the next step is a two week long welding process, followed by up to two weeks of being stress relieved. Proving this method is obviously vital for the P2, but the next build project - the V4 - will also require a fabricated monobloc cylinder. This method could also be applied to heritage locomotives, such as the V2.  

Fundraising is ongoing - find out how you can help support this impressive feat of engineering here. All members of the Monobloc Club are invited to visit Howco, where it is being fabricated, and view the Monobloc immediately after welding is complete.

General view of the front of the monobloc.

General view of the rear of the monobloc.

Measuring the front of the monobloc with the Faro gauge.

Measuring the rear of the monobloc.

Assessing the resultant measurements.