page_title: SR Leader class
section_title: Performance of No. 36001
hierarchical_section_title: SR Leader class / Operation / Performance of No. 36001
caption_attribution_description: English: Official photograph of the Leader locomotive taken at Brighton works. Taken in May 1949 by British Railways, a nationalised (UK government) concern. Source: Bulleid, H. A. V.: Bulleid of the Southern (Hinckley: Ian Allan Publishing, 1977) ISBN&#160;071100689X
context_page_description: The Leader was a class of experimental 0-6-0+0-6-0 articulated steam locomotive, produced in the United Kingdom to the design of the innovative engineer Oliver Bulleid. The Leader was an attempt to extend the life of steam traction by eliminating many of the operational drawbacks associated with existing steam locomotives. It was intended as a replacement for the ageing fleet of M7 class tank engines still in operation on the Southern Railway. Design work began in 1946 and development continued after the nationalisation of the railways in 1948, under the auspices of British Railways.
  The Leader project was part of Bulleid's desire to modernise the steam locomotive based on experience gained with the Southern Railway's fleet of electric stock. Bulleid considered that attitudes towards the labour-intensity of steam operation had changed during the post-war period, favouring dieselisation and electrification. In an effort to demonstrate the continued potential of steam, Bulleid pushed forward the boundaries of steam-power, allowing it to compete with diesel and electric locomotives in terms of labour-saving and ease of operation.
context_section_description: Following trials that lasted over a year, No. 36001 was shown to have several flaws, including heavy coal and water consumption, mechanical unreliability, untenable working conditions for both fireman and driver, loss of steam through the cylinder rings and uneven weight distribution on the bogies. After renewing the cylinder assembly, it was tested around Brighton and Eastleigh using an LNER Dynamometer car, where good running was experienced at high costs in fuel and effort on the part of the fireman. For a period of two weeks the Leader was tested against the performance of a U class locomotive which indicated that the brake release was too slow in service for use on tight schedules despite the brake application being noted as the best used on a Bulleid design. These trials were interrupted by breakage of the crank axles, these being replaced by axles from 36002 only for these to break in turn at approximately the same mileage as the originals.
  The sleeve valves, used to give greater volumetric efficiency and control over valve events, suffered frequent breakages at the "ears" where they attached to the valve gear.  The sleeves had a complex motion, combining rotation and reciprocation, to try and even out wear, and this was another untried design.
  Throughout No. 36001's trials, the firebrick lining provided a constant problem by continually collapsing into the fire. The firebricks were then replaced with cast iron substitutes that melted in the intense heat of the firebox, which were in turn replaced by thicker 9-inch (230 mm) firebricks. Some of the firemen allotted to the Leader complained about cramped conditions in the centre cab of the locomotive, a situation made worse by flames entering the cab from the firebox at high outputs. It was an enclosed space that was constantly hot and the single fireman's entrance door on the side of the locomotive was left open during travel to promote ventilation. The door into the fireman's cab also attracted criticism, as it would have been blocked in the event of the locomotive overturning on that side, preventing the fireman's escape, so that members of the railway trade union ASLEF threatened to stop their crews from operating the Leader. Measurements in the fireman's cab showed temperatures could reach 120 °F (50 °C) earning the locomotive the nickname of The Chinese Laundry due to the heat and humidity.
  During work on the crank axles at Eastleigh Works the opportunity was taken to place the locomotive on the weighbridge which showed that the offset boiler and coal bunker caused the locomotive's centre of gravity to be shifted to one side. Experiments had to be undertaken to balance the locomotive by filling the linking corridor with large quantities of scrap metal, replaced in a re-design by a raised floor, covering the weighted material. These modifications resulted in the engine exceeding the total weight limit of 150 tons (151 tonnes), severely limiting the design's route availability during testing. A related problem was that despite being a tall locomotive, at 12 feet 11 inches (3.94 m), the cab ceilings were relatively low. The cab at the smokebox end of the locomotive suffered from the same excessive heat as did the fireman's cab. To circumvent this problem the locomotive was used in reverse, as the rear cab was next to the water tank and coal chute and therefore away from the hot gases circulating inside the smokebox.
  Despite its problems, the locomotive displayed outstanding steaming characteristics and total traction from the two power bogies on its trial runs. When properly fired, the Leader was capable of keeping up with the schedules, even running ahead on occasions. However, operational difficulties when stopping for water tended to lose any time advantages gained and affected the published performance figures. Despite hauling test trains over the Central Section of the former Southern Railway, the Leader prototype was never used on a revenue-earning service because of the risk of failure of the valve gear and the adverse publicity this would cause for Britis
caption: The Leader being lifted onto its power bogies at Brighton, May 1949. The casing allowed the locomotive to be put through a carriage-washing plant.
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