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|It is probably no exaggeration to say that Bulleid's
"Leader" Class locomotive was probably the most controversial class
ever built, here or abroad. One thing that is certain is that everyone
has a view, be it favourable or unfavourable, on this class that, at best, can
only be labelled as a brave experiment in pushing forward the case for steam
during its dying years.
The origins of the "Leader" go back to a meeting in December 1944 to consider the Southern Railway's locomotive building programme. Whilst there was no disagreement on the proposal to build 25 more light pacific locomotives Bulleid suggested a further 25 of the Q1 Class (for which the materials were ordered and available) whereas the Traffic Manager wanted tank engines. He argued that the Q1s were not suitable for regular tender-first running as "the rear lookout on the driver's side does not give a sufficiently wide range of vision, and the absence of a lookout on the fireman's side is a serious drawback, having regard to the fact that it is necessary for the fireman to assist in looking for signals when not otherwise necessarily engaged". He also questioned whether they were suitable for maintaining the necessary speeds when running tender first and with a light load of coal and water. Bulleid agreed and, on 4th January 1945, their joint recommendation to the General Manager, Missenden, was for:
"25 Passenger Tank Engines (to be built from material ordered for the 25 Q1 Class)Missenden's reply, however, was that they should build 25 Mixed Traffic, 25 Freight and 10 Shunting engines, which left the Q1 material to be used as originally intended.
Meanwhile exploratory work was going on in the CME's department for adapting the Q1 to a tank engine, first as an 0-6-2, then as an 0-6-4, which, being about twice as powerful as an M7 Class tank, would have found great favour. But Bulleid apparently found them "stodgy and boring" and was more interested in a compact locomotive on two power bogies, a proposal he had made previously and now returned to. He was, however, persuaded against the idea and instead proceeded with experiments with duplicating the driver's controls of the Q1 so that the driver could operate from the fireman's side when running in reverse gear. NºC36 was used, and coupled to a light pacific tender made a number of high speed runs between Ashford and Maidstone, which resulted in a proposed "double-fronted" version of the Q1. The Running Department turned it down flat! Next came proposals for a 2-6-2T and a 2-6-4T, followed by a 4-6-4T, all using the Q1 boiler. This, however, only led to the double bogie idea again with all twelve wheels driven (based on an idea Gresley had looked at in 1928 for a multi-cylinder, geared locomotive) as it would have far superior adhesion. A sleeve-valve engine was proposed as it should reduce weight whilst, at the same time, increase efficiency. These ideas were eventually put to one side again and attention reverted to a 4-6-4T design with a 350psi boiler.
Come 1946 a year had passed since the agreement to build more locomotives, but still nothing had been decided for the 25 tank engines. The Traffic Department was demanding a new tank engine of considerable more power than the M7 Class tanks whilst the Government could not make up its mind on the question of coal or oil! Whilst the main opponent to the double-bogie proposal was absent, Bulleid pressed ahead and produced a drawing for an 0-4-4-0 in February 1946, but the projected weight was found to be far too great at about 20 tons per axle. Bulleid felt that with a different boiler and six wheeled bogies the weight problem could be cured and he declared the project, called the Type CC locomotive, to be the next steam project. The first "feasible" design was produced in April 1946 looking very much like a rigid light pacific with the locomotive and tender all one piece. Bulleid wrote to Missenden in July 1946 advising him that the proposed new locomotive would meet the Traffic Manager and Civil Engineers' requirements, would have a top speed of 90mph, would work any train that a Q1 or light pacific could work, could work 80 miles before requiring water and 150 miles without taking coal and would run over all the Southern Railway routes with the exception of just eight lines. Expected cost for a batch of 25 engines was forecast to be £17,000 each, whereas to build a one-off prototype would be in the region of £25,000. A meeting was held on 4th September 1946 to discuss the "Leading Class. Shunting Locomotive C.C. Type", for which a new drawing was produced, but still of a design reminiscent of a light pacific incorporating a tender in the body of the locomotive. No decision was taken because, wisely, a case was made that to commit to more than five of the new engines at that stage would have been foolhardy in that "They contain so many novel features that they are certain to have some initial troubles". Wise foresight indeed! However, the following day Bulleid was given permission to proceed with the construction of five engines to the latest drawing. The order was placed with Brighton works on 11th September 1946. The Traffic Manager, Richards, justified the decision in a letter to Missenden the following day on the basis that the most powerful passenger tank engines on the Western Section were the M7s, that they were out of date, inefficient and prevented any improvment on the services they operated and, indeed, had already been condemned to be withdrawn as early as 1950. 60 new tank engines of either steam or diesel would be required in addition to the 25 already proposed, and that the building of the first five will be a guide as to the construction of the remaining twenty.
Design and Construction
Enthusiasm for the new locomotive was now running high, but Bulleid was still troubled by the problem of the driving position. What did diesels and electrics do? They put the driver at the front. So, decided Bulleid, could steam. His next drawing had the boiler moved slightly to one side to allow for a corridor, and duplicated controls in a cab at each end. At last the drawing looked like the actual locomotive that was built, although it showed a corridor connection at each end of the engine. There were enormous problems to be overcome which the drawing office tackled with great enthusiasm.
One concept was to have an interchangeable power bogie, although it would require a fleet of 30 engines to justify holding spare bogies to keep the engines in service when their bogies needed an overhaul. With the Southern Railway being at the forefront of welding technology on Britain's railways it was natural that this technique was to be used to the maximum. The all-welded boiler contained 36 large and 283 small tubes and the firebox contained four syphons welded to the bottom of the barrel and the underside of the firebox drum. The blast pipe had five jets and TIA water treatment was included. The fitting of flexible steam pipes gave the power bogies the ability to negotiate curves down to 5½ chains. The boiler gave no problems, and steamed very well, but the firebox firebrick linings were very troublesome. To assist with cleaning out the smokebox a permanently open duct was fitted, with a cover worked from the cab, which got rid of most of the ash. In practice, though, this impaired steaming and it was abandoned to the detriment of the Poodlers! Sleeve valves were incorporated as, by eliminating the piston valve, they made it much easier to fit the engine into the tight space of the bogie and they allowed for shorter steam passages leading to improved thermal efficiency. A rotary movement of the sleeves was incorporated to reduce wear through improved lubrication. As a test bed, 2039 Hartland Point was so fitted and proved a great success with runs of up to 80mph.
Looking back at this project with the benefit of hindsight, it would probably have been a better idea if Bulleid had spent more time in the drawing office, as he had for the Merchant Navy and the Q1 Class designs. As it was, Bulleid was a rare visitor there.
Materials were ordered in December 1946 and construction began in July 1947 - then in November of that year a further 31 "Leaders" were sanctioned, though this was in the final run-up to nationalisation and they were never actually ordered. Although there was still a large amount of design work still to be done, the first frames were set up in Brighton works during May 1948. The folly of starting work before the drawings were completed soon became obvious as later, brighter, ideas were incorporated or errors and mistakes corrected by burning off or adding on to the welding, which all contributed considerably to the final engine coming out of the works overweight. Problems arose at virtually every stage except the boiler, some exacerbated by the hurry in which the loco was being constructed. The triple cylinder blocks were both warped after their finishing machining, due either to insufficient relieving of welding stresses, to being strained whilst welding to the frames, or some of both, leading to serious trouble in driving the sleeves. The second "Leader" would, no doubt, have been a lot more trouble free through being constructed in far less of a hurry. The first bogie was test run with steam from a nearby shunter and started at only 8psi. It ran really sweetly and relief was felt all round - until someone reversed the engine whilst it was running and buckled several of the motion rods and links. Despite all these setbacks, however, the first "Leader", Nº36001, steamed away to its trials in June 1949. Bulleid, however, was starting to lose interest in the engine as he suspected that British Railways would not tolerate such a novel engine, that he would undoubtedly be retired within a year or two and because he had been approached to go to Ireland to work as Consulting Mechanical Engineer to CIE. He did, however, believe that the "Leader" project would be continued by British Railways after his departure, so he planned to retire and leave for Ireland on 30th September 1949. Riddles, however, realised that the project needed Bulleid in order to succeed and persuaded Bulleid to stay until the end of the year, by which time he fully expected "Leader" to be in revenue service.
Testing and Development
The first major problem arose in November 1949 when Riddles realised that the fireman's job would be untenable and that to make it acceptable would involve major changes at high cost, so he ordered that work on the second to fifth engines should be stopped. Then in December, with the locomotive nowhere near ready for traffic, he arranged for Bulleid to stay at BR for another three months before departing for Ireland.
Finally, in March 1950, the engine was ready and Bulleid wrote to Missenden (now at Marylebone) and Riddles on 8th March saying that he was "quite satisfied the engine can be made a useful and valuable locomotive". However, two days later Jarvis at Brighton reported that the engine had many shortcomings, notably it would be too heavy for many of its proposed routes, the enclosure and lubrication of the engines, axleboxes and springs was very unsatisfactory, that its increased steam chest volumes and port areas, and the reduced clearance volumes, would have a minimal effect on Thermal Efficiency and that the firebricks used to replace firebox water-legs were not successful. He went on to say that the disappointing progress was more to do with the detail design than the broad conception. He said that self-aligning axle bearings were essential, that the fireman's confined space dangerous in the event of a blow-back, that the valve gear was unsatisfactory on three counts and that the wheels should have been smaller.
In the light of this damning report it was quite surprising that Riddles still supported the concept and wanted the trials to continue, unlike his colleagues. He was, however, looking at the wider picture as, having just announced the twelve "standard" designs of steam engine to be built by British Railways that, due to a lack of cash, were all based on the best of existing practice, he could see a steam future for any success that might emerge. Despite spiralling costs for the prototype (estimated in September 1948 as £100,000 against expenditure to January 1950 of £176,000) the engine was being prepared for dynamometer car trials, and that if these showed significant advantages consideration would be given to continuing to build the remaining engines. This would have to address the weight problem which, at 24½ tons was 5½ tons over the weight estimates given to the Civil Engineer, plus a side-to-side variation of 10 tons. The Railway Executive endorsed his decision and "Leader" was off for dyanamometer trials.
The trials proved interesting and incorporated such highs for those involved as exhilarating high speed runs or lows such as sitting and watching for malfunction of the valve rods. Six draughtsmen were nearly suffocated due to a freak vacuum created in Crowborough tunnel and at one time the loco carried 18 people on the footplate at the same time. The loco also attracted many visitors, including M. Chapelon who was very interested in the sleeve valves and the four syphon arrangement.
As the trials progressed various modifications were carried out, such as more clearance to axlebox pedastals, ballast added on one side to correct trim, the firebox lining thickened, the clearance in the liners doubled, the back ring removed from the sleeve valves and the oscillating gear removed from the valve gear. Poor steaming caused by the reduction in grate area following the increase in firebricks was remedied by reducing the size of the blast pipe nozzels, but this led to excessive fire-throwing. To correct this a brick arch was added, but this caused flames to lick around the firehole door, worsening the fireman's position. The rocker grate originally fitted was removed and replaced by a drop grate. To alleviate over-travel of the valves maximum cut-off was reduced to 65%, but this led to poor starting. Furthermore, there were a number of other problems that were on the "to do" list, such as the motion pins corroding in the oil bath, the main cause of which was leaving the engine standing with water in the sump, the brake release time was too long, circlips tended to break and allow motion pins to fall out and oil was being wasted due to the unsatisfctory drive to the circulating pump.
The result of all this was that a poor report following the dynamometer trials was issued in December 1950, with the decision to scrap the whole project being taken in March 1951 when more electrification and diesels were in prospect. Capricious to the end, 36001 "Leader" made a last trip on 2nd November 1950, after the dynamometer car had been returned to Darlington, during which it took a 480 ton train, accelerated it to its permitted maximum of 50mph and held the section times whilst showing what could have been!
The abandonment of the "Leader" programme was not, however, the end of the double bogie experiment as Bulleid managed to persuade his new bosses in Ireland to allow him to build a turf burning version at Inchicore. Building on the knowledge gained at Brighton this was far more successful than the "Leader", but was never developed beyond the prototype. That, however, is a story for other pages.
This page was last updated 16 Ocober 2008