June construction update

General – We have reached that period in the project where there is a lot of essential but relatively unspectacular work going on including pipework and electrics, brake gear details and fittings. Having said that, the tender tank has been ordered and we are on the cusp of ordering the boiler.

Frames – We have at last received the first of the two outside motion brackets and following inspection, these will be fitted to the frames.

The last of the frame components in the form of the remaining 10 spring hanger brackets have been ordered from North View Engineering Solutions. The original designs used steel castings, however as they are all handed and are mostly different from one another, the pattern costs would be considerable. On first look they are similar to those on Tornado, but on closer examination and resulting in part from the difference in coupled wheel sizes, they are longer from top to bottom than the A1 type, preventing use of the Tornado patterns. They have all been redesigned as welded fabrications and the two pairs which are joined together across the frames – on the P2 by bolting a heavy section angle irons between them, have been replaced by the significantly stronger one-piece design employed on the A1 class.

Two of the spring brackets have bearing housings attached to the back of them to support the brake lever shaft for the rear pair of coupled wheels. As we have modified the design of the brake lever from vacuum to air operation which has slightly altered the distribution of forces in the brake lever shaft, the spring hanger brackets with brake shaft bearings have been subjected to Finite Element Analysis (FEA) by Daniela, which after a subtle improvement to some weld profiles, have been shown to have an adequate margin of strength and fatigue resistance.

The fitting of the motion brackets and spring hangers will complete the engine frame structure.

Wheelsets – After further protracted delays, the pony truck cannonbox is back with Timson Engineering at Kettering for final machining following replacement of some of the manganese steel wear plates. Delivery to Darlington is eagerly anticipated.

Our volunteers are making good progress with polishing the tyre rims.

The speedo drive return crank (which doubles as the crank pin nut on the LH trailing coupled wheel) has been delivered and is presently being fettled and polished by our volunteers.

Boiler – The draft of the updated boiler design has been received and “best and final” updates for quotes for the boiler sought. By the time this article appears in TCC, we expect the decision on supplier will have been made and contract negotiations to be well in hand.

Major boiler fittings – Preparations are being made to carry out the hydraulic test on the superheater header (including finding the 86 rubber dog balls required to block the superheater element connection holes).

Cylinders – Further detailed design work has been done on the cylinder block and valve gear in anticipation of commencement of manufacture. In the meantime Alan Parkin has produced drawings and quotations for valve cover patterns have been sought.

Brake rigging – four fabricated brake cross stays (similar to those made for Tornado) have been delivered by North View Engineering Solutions.

The front and rear short brake links have been completed, the latter being a complicated offset design which have been machined from solid at Darlington Locomotive Works. Brake blocks have been ordered and all the brake pins made. We are expecting delivery of the two brake lever shafts from I D Howitt at Crofton shortly.

Cab – With Daniela having completed the drawings, material has been delivered and cab seats and cab seat cubicles are under construction.

Tender – The order for the tender tank has been placed with North View Engineering Solutions. Delivery of the base plate to Ian Howitt at Crofton is scheduled for pre-fitting to the frames during June, with the completed tank delivered to Darlington Locomotive Works in September, by which time we expect to have the frames on site.

Ian Howitt continues to make good progress with the tender frames with the spring hanger and tank brackets attached to the frame plates. Major components have been made including the drag boxes.

We are still awaiting delivery of the remaining tender axle, with a current promise for mid-June. At that stage the four axles will be dispatched along with the wheels to South Devon Railway Engineering.

Fittings – Our first attempt to appoint a machinist was not successful, so we have re-advertised the job. In mean time urgent fittings and machining work is being subcontracted out.

Efforts are being made to secure the loan of patterns from the 71000 Duke of Gloucester team for the Davies and Metcalfe class K exhaust injector. Manufacturers are also being sought for the grease separator which is located in the exhaust steam pipe to prevent oil and grease from the exhaust steam being injected into the boiler.

Pipework – The critical path on project plan is pipework, so effort has been concentrated on design and installation of the major pipe runs.

The first to have been made is the exhaust steam injector exhaust steam pipe – a 4in bore pipe which carries exhaust steam from the cylinder block all the way back to the exhaust steam injector under the cab; being the largest pipe we have to accommodate it was routed and made first with Ian Matthews fabricating it. It has been trial installed but each of the sections will require hydraulic testing before permanent installation. This pipe also serves as the exhaust pipe for the two air pumps.

The next pipe run will be the 2in vacuum pipe including the DV2 air/vacuum proportional valve.

Design is well in hand for the air brake and air reservoir pipes which also run the full length of the frames.

Electrical – The casing for the new belt driven alternator prototype has been fabricated by North Bay Railway Engineering in Darlington and has been christened “Noo Noo” due to its similarity in appearance to the vacuum cleaner in the Teletubbies!  Meanwhile Alan is seeking quotes for the remaining detail components.

Alan has made very good progress with routing the stainless steel electrical trunking and conduits through the frames. He has also worked up a design for a slightly enlarged battery box which will permit fitting of batteries of greater capacity than those on Tornado to provide greater margins for when the ERTMS cab signaling system eventually has to be fitted to the locomotive. The new battery boxes look very similar to the BR AWS (Automatic Warning System) battery boxes fitted to Tornado which is somewhat anomalous as P2s were never fitted with AWS!. However, we do not have enough space to locate the batteries anywhere else so have adopted the same location as Tornado. The BR design is not very conspicuous and had the P2s survived into original form into the 1950s, they would have been fitted with AWS.

One change we are making from Tornado design is the means of disconnecting cables between the cab and frame so that the cab can be removed from the engine – which is often needed for firebox repairs. On Tornado, the cables from the frames pass through holes in the footplate and the bottom of the brake equipment cubicle in the cab floor and plug directly into the equipment in the under-seat cubicles. The process of disconnecting these requires great care and leaves the cables with their connectors hanging from the trunking above the battery boxes where they are vulnerable. The chosen solution is to set military standard plug sockets in recessed boxes in the underside of the cab base which enable short cables to be plugged in directly. When the cab is removed, the plug sockets have dummy covers fitted and the cables and plugs (which are much shorter) can be coiled up and stowed in the trunking above the battery boxes.

A further electrical design review has been conducted with Rob Morland, Alan Parkin and David Elliott to assess the design work to date and decide if any changes were needed. Fortunately, very little alteration was felt to be required, and Alan is clear to proceed under Rob’s direction to complete the detail design of the trunking installation.