Build : Last updated on 06/06/2023
This section aims to tell the story of building a modern steam locomotive. You can read the build diary by following this link. The Build Diary provides a month by month account of the building of Hengist.
1. Frame Assembly
All of the components to assemble the frames have now been manufactured and machined, they are in store at CTL Seal's premises in Sheffield and an order has been placed on CTL Seal to assemble the frames. We have spent a lot of time in checking the frame alignment and the fit of the frame plates on the cast steel stretchers. In September 2019, specialist from Hexagon Metrology came to measure the frames with their latest laser scanning systems. This proved that the alignment was virtually correct and a small amount of correction was needed. In September 2020, the frames were transferred to the assembly shop at CTL Seal for the important machining of the hornguides. The hornguides are the 3 per side, U shaped openings in the frames which contain the axleboxes. The hornguides have been machined so that they are in line across the frames.
The cast steel frame stretchers differ from those of the first 10 Clans which were fitted with fabricated stretchers. This was a lot 242 modification which followed the change for 71000 Duke of Gloucester; this having cast steel stretchers in an attempt to avoid frame cracking in the area of the hornguides.
A large part of 2022 has been fitting the frame extensions to the main frames - a critical join. Also in the same area is the front firebox support stretcher and pony truck pivot. In some places, a bolt needs to go through 4 different components. Each bolt hole has had to be drilled and reamed until it is truly circular and parallel. The hole is then accurately measured and a bolt manufactured to fit that hole. This is near completion with the final bolts in stock to be fitted. In 2022, SSLC dicovered that a new design of dragbox had been designed by British Railways as existing dragboxes were becoming distorted. A new dragbox to this design is in the final satges of design. The front buffer beam has been riveted in place.
2. Main Cylinders
The manufacture of the pattern and the casting of the main cylinders is a long term job and we reckon that it will take 3 to 4 years to manufacture the complex pattern. Work is well underway on this job and our pattern maker, Tony, has provided a comprehensive step by step account of how you make a complex pattern, as is required for the cylinder casting. You can follow progress by clicking the link below. All CAD design work is complete and the motion cylinder pattern is complete. Work is in progress on the valve cylinder pattern and the main flange that allows the cylinders to be bolted to the frames. The complex part of the job is creating the "cores" for the internal air spaces and the necessary transfer passages and unions. We have a sponsor for the casting of the cylinders.
3. Front Bogie
The design team have almost completed work on the front bogie. We have all the drawings and have built the CAD model for the main front bogie casting and associated components. All of the components for phase 1 of the bogie construction are in stock and assembly has commenced. A challenge is the side control springs which are a rectangular section, coil spring. At the moment we have not located a supplier who has the capability to produce a spring of this size. All of the components for phase 2 - wheel set assembly - are in stock and the components will be delivered to South Devon Railway Engineering soon. You can follow the bogie build below.
4. Trailing Truck or Pony Truck
The next task in the build plan will be to manufacture the trailing truck. With the front bogie and trailing truck fitted to the frames, we have the ability to more easily move the frames, if required. The trailing or delta truck for the lot 242 Clans follows the same design of 71000 Duke of Gloucester in having a coil sprung truck. Keith Collier who was the Chief Engineer for 71000 (and who worked at Crewe Works) has said that 71000 was one of the best riding locomotives he travelled on. We expect to start detailed design work on the trailing truck soon.
Although we have reproductions of most of the British Railways drawings for Hengist, we are finding that a drawing to modern standards is appreciated by suppliers. Most suppliers operate in metric measurements and the BR drawings are imperial. First we create a 2D drawing to modern standards, converted to metric. Then we take the 2D drawing and transpose it into our 3D model. This identifies any errors before metal is cut.
The tender can be developed in parallel with the locomotive so we are looking at policy decisions for the tender. You can see some of our thoughts by following the link below. A number of small components for the tender have been constructed.
The boiler is a long lead item and we already have had discussions with potential suppliers. There will be restrictions on the type of arsenical copper, traditionally used in locomotive fireboxes. There are alternative types of copper that could be used or we could follow Bullleid's lead with a steel firebox. There is an issue with steel fireboxes in that steel has only 30% of the heat conductivity of copper. Whatever we do, there is a considerable amount of design work required before we can consider placing an order for manufacture. The smokebox and cab have already been built to provide a showcase for the project.
Below, you can find links to more detailed information on particular components or issues. We hope you find them interesting! Please click on the links (if available) below to view the articles. If the link isn't available, we're currently working on it and will have information on this shortly.
|Frame Assembly Phase 1||Last updated on 09/03/2023|
|29/08/2020 - Riveting of Frames||Last updated on 30/08/2020|
|Exhaust Steam Manifold||Last updated on 24/06/2019|
|Frame Assembly Phase 2||Last updated on 21/09/2021|
|Front Bogie||Last updated on 06/06/2023|
|Pony or Trailing Truck||Last updated on 23/08/2022|
|Main Cylinders||Last updated on 16/02/2023|
|Casting - Cores and Prints||Last updated on 27/05/2021|
|Tender||Last updated on 24/06/2019|