'Sapper' takes an Up train out of Darley Dale. (Photo: Sheila Rayson)
Brief Locomotive History
'Sapper' was built by Hunslet in Leeds in 1944. The Works Number was 3163 and she was very similar to other six-coupled saddletanks built for military service during the Second World War. When 'de-mobbed' this locomotive, and some other members of the class, were acquired by Hunslet. Their aim was to sell-on the locomotives for industrial use. To make the locomotives more attractive to industry (which was, by then, more interested in diesel locomotives or rejecting rail altogether, in favour of road transport). Hunslet converted the locomotives to a Gas Producer Combustion System based on the work of the Argentinian engineer L. D. Porta. There's an excellent article by Martyn Bane on the 'Austerity' class as built and as modified here.
The Hunslet initiative wasn't an unqualified success and, whilst a number of 'Austerity' saddle tanks (both modified and un-modified) have ended up in preservation, I think all the ones actually in use have reverted to a more conventional firebox design and hand firing.
Of course, as-built the 'Austerity' locomotives were not provided with steam-heating facilities but restored locomotives used for passenger trains on preserved railways have this feature added. In preservation, warming is typically carried out at a steam pressure of about 30 pounds per square inch.
'Sapper' is provided with a handbrake and a steam brake. On each wheel, there is a cast-iron brake block which can be pulled against the steel tyre of the wheel through a substantial arrangement of brake rods and cross-members forming the brake rigging. The brakes are applied on all wheels simultaneously either by rotating the handbrake screw using an l-shaped handle in the cab or by the movement of a piston rod connected to the piston in the steam brake cylinder. The steam brake cylinder is mounted under the footplate on the driver's side of the footplate and the supply of steam to the brake cylinder is controlled by a valve in the cab.
MIC - Brakes.
As-built the 'Austerity' locomotives were not provided with vacuum brakes but restored locomotives used for passenger trains on preserved railways have this feature added. In 'Sapper' a Davis and Metcalfe Type 'M' Ejector including the Driver's Brake Application Valve has been fitted.
Related posts in this blog
Preparation of Locomotive 'Sapper'.
'Sapper' Austerity Tank Locomotive.