SR Leader Class
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The Southern Railway’s Leader Class was a class of experimental 0-6-6-0 articulated locomotives, produced to the design of the innovative engineer Oliver Bulleid. Five were ordered but only three, numbers 36001-3, were put into construction, appearing after nationalisation in 1948. Only the first locomotive was steamed.
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[edit] Overview
These locomotives had an unusual configuration, with two steam bogies that utilised sleeve valves and chain drive. They could be driven from a cab at either end, where the controls were duplicated, and two or more could be controlled in multiple by one driver. The boiler and “tender” were placed on a common frame (thus it is often referred to as an 0-6-6-0 tank engine), with the boiler placed horizontally, off centre by six inches to allow for a corridor to link the fireman's central compartment and the cabs. The overall body was streamlined, the complete machine resembling a modern diesel locomotive rather than a traditional steam engine.
[edit] Mechanical
Each of the two bogies had three cylinders and the driving wheels were connected by chains. The valve gear used an unusual sleeve valve arrangement, chosen because of the restricted space in the powered bogies, that had been tested on the ex- LBSCR Atlantic Hartland Point.
36001 was the only one steamed, the others only reaching various stages of completion. It was found to be a poor steamer. The welded boiler, with thermic syphons through the firebox, was designed using the experience gained in Bulleid’s highly successful Merchant Navy Class but the firebox itself, originally built without a brick arch, together with the special arrangements needed to allow for smokebox cleaning, made for poor blast. It was originally intended that the locomotives be oil fired but the unforseen increase in the cost of imported oil in the post war austerity period lead to a reversion to coal firing. The compartment for the fireman was excessively hot and cramped, to the point where volunteers had to be called for to work it. Their lot was not improved when, as part of the changes necessary to change from oil to coal firing, a brick arch was eventually incorporated, as there was then a tendency for flames to enter the cab.
The off-set boiler needed two and a half tonnes of lead alongside to level the engine, resulting in a great increase in axle load (causing track damage as it was pushed out of gauge). The chain driving the sleeve valves also gave trouble, stretching over time and making the timing unpredictable. In addition, the reversing gear often jammed. The tank filler cap was above the standard water tower height and special arrangements had to be made, wherever the locomotive was run, to take on water.
[edit] History
Following trials lasting over a year, 36001 was shown to have a number of inherent flaws, including heavy coal and water consumption, mechanical unreliability, untenable working conditions for the fireman and uneven weight distribution. It was tested around Brighton and Eastleigh using the LNER Dynamometer car (the one used by LNER 4468 Mallard on its record-breaking run). The whole concept was quietly dropped after Bulleid had departed to become Chief Mechanical Engineer of Córas Iompair Éireann (where he produced a similar peat-burning locomotive) and all three were scrapped.
Public opinion saw the project as a great disaster, wasting £500,000 of taxpayers’ money. [1] Today, all that is left of 36001 is one numberplate in the National Railway Museum. In addition, the numberplate from 36002 is believed to be in a private collection.
[edit] Reference
- ^ Sunday Dispatch, January 18, 1952
[edit] External links
| Locomotives of the Southern Railway | |
| Maunsell: | H15 - Lord Nelson - N15 (King Arthur) - N15X - Q - V (Schools) - U - U1 - W - Z |
| Bulleid: | Leader - Merchant Navy - Q1 - USA - West Country/Battle of Britain |
