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Latest Status - 25 June 2021

All of the major components to start the assembly of the dragbox area are now in stock and are awaiting assembly. The outstanding items to procure are the rear firebox supports, the trailing truck pivot pin and the trailing truck centring pin.

After completing the bogie frame (phase 1) our plan is to assemble the components that sit around the dragbox at the rear of the frames.

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The dragbox is situated at the rear of the frame extensions and is the brown component you can see sitting between the 2 blue frame extensions (click image for a full size view). The vertical hole is where a large pin is located that engages with the locomotive/tender drawbar. The dragbox is in stock and will be fitted, together with the frame extensions. We expect that work will commence in this area shortly./ Fitted to the rear of the dragbox is the hind beam. Gussets (yellow and green) strengthen the ends of the hind beam and allow the weight of the rear of the locomotive to be transferred to the trailing truck frame. On the rear face of the hind beam is the central intermediate rubbing block. On each side of this are the 2 rubbing plates. All 3 components have manganese steel rubbing plates on the rear surfaces to minimise wear. On the bottom face of the gusset is the pony truck bolster. This is a plate with a dome facing downwards which engages in a bolster cup which is free to "float" on the oval plate on top of the pony truck frame.

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This is a rear view of 70000 Britannia's hind beam when under overhaul. The class 7 Britannia frame assembly is very similar to class 6. Thanks to Nigel Fraser Ker for allowing us to reproduce this photo. This shows the central intermediate rubbing plate, the outer rubbing plates and the pony truck bolsters fixed to the gussets. The frame assembly is sitting on a temporary truck.

The next stage in frame assembly will be to

All of the specialised fasteners are in stock.

Hind Beam
The hind beam is a flat plate that is attached to the rear face of the dragbox. We have 2 hind beams currently sitting under the front buffer beam. One appears to have been drilled and one has a small number of holes drilled. We need to extract the hind beams and assess what work needs to be done to determine which one we take forward.

Status - Ready for Assembly
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Intermediate Rubbing Block
The Intermediate Rubbing Block is fixed centrally on the hind beam. The engine drawbar goes through the central "mouth" and 2 manganese steel liners are fixed above and below. This rubbing block presses against a similar rubbing block on the tender.

Status - Ready for Assembly
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The Intermediate Rubbing Block on the machine bed at CTL Seal
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Final profiling in progress. Manganese Steel liners plates will be welded to the curved surfaces. Highslide JS
Outer Rubbing Plates
Two Rubbing Plates are fixed to the hind beam. The tender has 2 sprung buffers on the front face which press on these plates. Manganese liners are fixed in the rubbing area.

Status - Ready for assembly
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Hind Beam Gussets
On either side of the dragbox, outside of the frame extensions, a large gusset is fitted to strengthen this area. It also allows the weight of the rear of the locomotive to be transferred to the pony or trailing truck.

Status - Ready for Assembly
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Machining part complete. The bosses on the bottom face that engage with the pony truck bolsters still need to be machined. Highslide JS
Machining complete. Highslide JS
Pony Truck Bolsters
Bolted to the bottom of the gussets are 2 pony truck bolsters. This is a photo of the pattern which we have in stock. The bolster is fitted with the dome facing downwards. It engages in a cup which is free to "float" on the orange oval plates which you can see on the CAD model at the top of the page. The pony truck is a "delta" truck as the weight of the locomotive is transferred on 3 bearing areas.

Status - Ready for Assembly
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The bolsters have been cast by South Lincs Foundry and are now in stock at CTL Seal. Highslide JS
Stage 1 machining complete. The lubrication grooves need to be machined together with the bolt holes. On the reverse side a deep recess is required which will engage with bosses on the gussets. Highslide JS
Rear Firebox Support

Bolted to the top of the of the gussets are 2 rear firebox supports. The grey component is fixed to the frames; it has a manganese liner fitted to the top face. The red component is fixed to the bottom of the firebox - you can see a 45 degree hole for the lubrication pipe. The cream components form a clamp, preventing vertical movement but allowing fore and aft movement to accommodate the boiler as it expands and contracts.

Status - Sponsors required for parts

Shoe (red) - 2 off required @ £1,170 each
Bracket (grey) - 2 off required @ £820 each
Clip (beige) - 4 off required @ £603 each
Liner - 2 off required @ £450 each

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Trailing Truck Pivot Pin

The stretcher at the rear of the main frames provides the support for the front of the firebox and also the housing for the trailing truck pivot pin. The exploded diagram shows the location of the pin. The main body of the pin has a convex curve form (i.e. it bulges outwards in the middle) to allow for trailing truck to move with the locomotives suspension in pitch and roll.

Status - Sponsors required for parts

Pin - 1 off required @ £1,220 each
Large Washer- 1 off required @ £60 each
Cotter - 2 off required @ £60 each
3 inch Nut - 1 off required @ £240 each

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Trailing Truck Centring Pin

Attached to the bottom of the dragbox is the centring pin. This engages in a hollow beam which is the rear of the trailing truck frame. Inside the beam are 2 pairs of side control springs; each pair on one side of the centring pin. This provides for side control into and out of curves at the rear of the locomotive. We are told that this is an area that can be difficult to keep clear of ashes from the firebox.

Status - Sponsors required for parts

Centring Pin - 1 off required @ £2,370 each

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