Engineering up-date - May 2018 2018

Locomotive Frame Assembly

Work continues on the construction of The Unknown Warrior at number of locations.

I have said before that building a full size steam locomotive is not an easy task. The past 3 months have been one of increasing frustration due to delays in supply of parts from suppliers or poor quality work which has led to the rejection of a number of components that were not of sufficient quality to be used on The Unknown Warrior. This will have an effect on the assembly of the locomotive as the parts are long lead time replacements.

We have also had a number of issues with Llangollen Engineering as mentioned in David’s Chairman’s thoughts. We hope these have finally been resolved. The amount of man hours devoted to these tasks has been considerable and has an impact on progress on other tasks.

This means very little physical progress to report at Llangollen. Parts are still under manufacture away at our suppliers and are being delivered to Llangollen on completion.


Construction of the boiler for the Unknown Warrior continues to make good progress at Heritage Boiler Steam Services.

The Inner & Outer Fireboxes. Photo – HBSS

Work has been focused on the assembly of the Outer Firebox, prior to installing the Copper Inner Firebox.

The Firebox Side Reinforcement Plates have been riveted in place. The taps for the Transverse Stays which run across the width of the Firebox have been ordered.

A view inside the Outer Firebox showing the side re-enforcement plate prior to riveting in position. Photo – HBSS

The Outer Firebox Wrapper showing the side re-enforcement plate rivets. Photo – HBSS

The steel Outer Firebox Wrapper, Doorplate and Throatplate have all been undergoing extensive work, marking out and drilling the hundreds of stay and rivet holes.

The Throatplate temporarily bolted to the Outer Wrapper. The re-enforcement plate and Foundation Ring can also be seen. Photo – HBSS

The fit of the Doorplate and Throatplate flanges to the Wrapper has also been subject to fitting work to achieve the required fit. This has required temporarily fitting the flanged plates in position, marking out, drilling, measuring etc.

The Doorplate temporarily bolted to the Outer Wrapper. Photo – HBSS

The Foundation Ring fit has also been checked ready for the final assembly of the Firebox.

The Foundation Ring trial fitted. Photo – HBSS

For the Future the assembly procedure has been decided and orders are in place to ensure we have the right parts in place when required. We are planning for a temporary coming together of the chassis and boiler in the autumn to check alignment before final assembly of the boiler commences.

The Throatplate temporarily bolted to the Outer Wrapper. Photo – HBSS

The Foundation Ring in position with the outer Wrapper, Doorplate and Throatplate. Photo – HBSS

Locomotive Chassis

Due to the issues at Llangollen outlined above and the late delivery of components, there appears little outward appearance of progress on the chassis at present. In fact, work is being undertaken on the assembly of various motion parts in preparation for assembly of the Valve Gear. These include the refurbishment of the legacy Radius Rods and Combination Levers. On the new motion parts such as the Outside Eccentric Rods and Inside Combination Levers, the bushes are being pressed in and Oil Pot Caps are being fitted. Fitting work to the relative Pins is also being undertaken to ensure correct tolerances.

One big disappointment is we are now waiting for delivery of replacement castings for several parts of the Reverser Shafts following unacceptable machining.  This will have an effect of the timetable for the assembly work on the chassis.

Not an acceptable bearing surface! Photo – Kevin West

We have been working with Llangollen Engineering to establish a work schedule to ensure the chassis completion moves smoothly from now on. A large task list is being agreed for the coming months.

The Cab Reverser Unit is making slow progress at Harco. The main stumbling block is the Leadscrew thread. This thread is 2” dia, triple start, of triangular form. The design is pure LNWR from the late 1800’s and was used on the Precursors and Claughton’s before being fitted to the Patriots. All parts of the Reverser units are now finished with the exception of cutting the male and female threads. The Reverser Nut is made of two pieces of cast iron, bolted together with a ¼” thick brass strip sandwiched between. The thread is cut along the centre of this brass strip. The Nut is 12” long and requires the thread cutting along the full length.

Lever for the Cab Reverser unit. The surface finish requires polishing. Photo – Kevin West

A selection of parts for the Cab Reverser unit. Photo – Kevin West

A special tap was ordered to cut this thread, but unfortunately the tap supplied was for a square form thread and not the triangular form required. We are now investigating other ways of cutting this female thread. The male thread will not be cut until the female is complete. We have found a couple of possible manufactures that may be able to cut this thread and are about to start the technical discussions.

Reverser Nut & Square form Tap. Photo – Kevin West

Brake System and Lubrication System

Work continues on installing the lubrication system pipework.

The Braking system on the locomotive is almost ready for completion. The new Brake Cylinder required a small amount of machining that the supplier was unable to do due to sickness of their staff, so we agreed to undertake this at Llangollen. Subsequently, this was undertaken at Harco, but during the movement of parts between the 2 sites some parts went missing. We have finally reached agreement over supply of replacement parts, although these will also need some machine time due to the sickness issues at the suppliers! Once done this will allow the Brake Cylinder to be fitted and the Brake installation completed.

Refurbishment of the original 9” Tender Brake Cylinder from 8F 48518 continues at Harco Engineering.

Pistons, Valves and Motion

Work is progressing on the procurement and manufacture of the remaining Inside Valve Gear parts.

The Return Cranks have been delivered to Llangollen and wait trial fitting ahead of the assembly of the Valve Gear.

Design work is progressing on the Piston Rod Glands and Covers plus Squab Boxes for lubrication of the Piston Rods. These are based on those fitted to the Black 5’s as no drawings of the originals have been found. Castings for the bronze spring mountings have been ordered and the design for the Cast Iron packing Pieces and rear Covers is being finalised prior to ordering castings and springs.

Manufacture of the new Inside Radius Rod is almost complete at Harco. This just need final polishing to eliminate the machining marks before delivery to Llangollen.

Inside Radius Rod. Photo – Kevin West

The Intermediate Reach Rod has been machined at CMS, Coalville and is ready for delivery to Llangollen.

Intermediate Reach Rod following machining at CMS Cepcor. Photo – CMS


Drain Cock Gear, Cylinder Relief Valves & Sanding Gear

The replacement casing castings for the Cylinder Relief Valves have been another delay. The original supplier has not been able to supply replacements within our required timescale so we have had a pattern made and new castings supplied. These will be machined in the near future and supplied to Gloucester for assembly and testing. The original castings will be returned for refund of the costs.

Without these parts the Valves cannot be completed and tested allowing fitting to the locomotive which has a knock on effect on delaying the installation of the rest of the Drain Cock operating gear.


We continue sourcing fittings required for the locomotive.

In our last report we mention we were searching for a pair of Steam Heating Shut Off Valves. A pair have now been purchased from our friends at Tyseley Locomotive Works.

Work is in progress to source the many other fitting that are required to finish the locomotive.


Work had re-started on the preparation of the Tender chassis for riveting with the countersinking of numerous holes. This work was also affected by the issues at Llangollen. The completion of riveting the Tender chassis is now high on our list of task for early completion.

We have been in discussion with another restoration group regarding taking the riveted chassis and undertaking all the work to complete the rolling chassis. These discussions are still at an early stage.

We are also in detailed discussion with a possible supplier of the new Tender Tank. The discussions are encouraging and the price quoted is in line with our expectations. We expect to be able to place an order in the near future assuming agreement can be reached over timescales and details.


Future Work Planning

Areas of existing design work include, Boiler Cladding Sheets, Cab Footplate structure and Tender Tank.





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