Cylinder design and fabrication progress

During this time design work on the P2 continues. Below you can see the cylinder block 3D CAD image, as at present, designed by David Elliott. The second image shows an interesting ‘skeleton’ view of the welds that will be used.  The 3D CAD design of the cylinder block and valve gear is now substantially complete; further progress has been made in applying the weld details to the cylinder block inside exhaust passages. Particular attention has being paid to the order of fabrication to ensure that all welds can be completed properly.

Alan Parkin has rebuilt the 3D model of the cylinder block to make it more manageable – this has meant the total file size has now grown from around 25mb to over 250mb!  The finished block will weigh approximately five and three quarter tons and will include a quarter of a ton of weld.

Although The Cylinder Club has reached its target and been closed, The Motion Club is still open and just another 15 members would see it reach its anticipated total as well.   You can join The Motion Club by making a single donation. This form confirms your personal data and your £1,000 donation – please DOWNLOAD, print out, complete and return it to us with a cheque for £1,000 made payable to “A1 SLT – P2 Construction Fund” at the address shown. To pay by credit card, please contact the office on 01325 460163 or email .

You can also join The Motion Club by making multiple donations by Standing Order. This first form confirms your personal data and the amount that you would like to donate – please DOWNLOAD, print out, complete and return it to us at the address shown. This second form confirms your bank details, please DOWNLOAD, complete in full and return it along with the monthly donation form, we will then forward it to your bank.

In addition to the design work of the cylinders themselves, work has been progressing on the production and assembly of the cylinder drain cock gear.  For those unfamiliar with these, the drain cocks overcome an inherent problem with steam locomotives, that of water condensing in the cylinders themselves.  Since water doesn’t compress well, starting a piston-valve or poppet fitted locomotive with water in the cylinders can result in significant damage.  To allow this water to escape steam locomotives are fitted with manual (sometimes steam operated) drain valves, three per cylinder, actuated from the cab by the locomotive crew.  The drains are normally left open when the locomotive is standing and for the first few revolutions when it starts moving, allowing egress of any condensed water, hence the clouds of steam in front of British locomotives when they initially start moving (US and European locomotives often have the valves aimed outwards from the cylinder).  In addition the cylinder ends are usually fitted with a pressure relief valve but this is designed to release excess steam rather than water.  To operate all three sets of drain valves simultaneously, cross shafts and a linkage back to the cab are required, all of which have to be fitted between the locomotive’s frames or along some other route from the front of the engine to the lever in the cab, in this case on the fireman’s side.
Cylinder drain cock linkage rocker bracket – Daniela Filová
Cylinder drain cock linkage rocker bracket and in-to-out bracket – Bob Hughes
Cylinder drain cock linkage rod ends – Bob Hughes
Cylinder drain cock linkages – Daniela Filová
Cylinder drain cock linkages – Daniela Filová