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The Leyland Titan was a forward-control chassis with a front-mounted engine designed to carry double-decker bus bodywork. It was built mainly for the UK market between 1927 and 1942, and between 1945 and 1969. The type was widely used in the United Kingdom and it was also successful in export markets, with numerous examples shipped to Australia, Ireland, India, Spain, South Africa and many other countries. From 1946 specific export models were introduced, although all Titans were right-hand drive regardless of the rule of the road in customer countries. After Leyland ended the production of the Leyland Titan in UK, Ashok Leyland of India took up production and marketed the bus in South Asia as the Ashok Leyland Titan, which, in much developed form, is still in production. ==Origin== Prior to 1924 Leyland Motors and the majority of other British commercial vehicle makers had used similar chassis frames for bus and lorry chassis, generally a simple straight ladder-type steel frame. The disadvantage for bus applications was that the saloon floor was relatively high, which gave passengers access difficulties and also caused stability and overall height problems if a double-deck was to be fitted with a top deck cover, as was increasingly becoming common on double-deck trams in the UK and had been first used on buses by Widnes Corporation in 1909. When the London General Omnibus Company, part of the Underground Electric Railways of London Group proposed a closed-top double-decker to the group's vehicle-building subsidiary the Associated Equipment Company in 1923, the model 405 was produced, forming General's NS class, this had a frame with side members upswept over the axle mounting points so that the lower saloon floor level was about one foot lower than the preceding types 301 (K-class) and 401 (S-class). However, the Metropolitan Police, who then had the statutory responsibility for London bus construction and safety rules, refused the fitting of covered top decks on the NS class for a number of years to come. Also initially the NS was built exclusively for the Underground Group, and certain features, such as the four-cylinder side-valve engine and three-speed chain-drive constant-mesh transmission were obsolescent. In 1924 Maudslay of Coventry also introduced a swept-down chassis frame on a comprehensive range of purpose-built passenger models called the ML series, although no double-deckers were catalogued until 1930. In 1925 Leyland Motors followed suit, unlike the competitors they had a dropped-frame double-deck model for general sale, and unlike them, Leyland decided to publicise their new range of dedicated passenger models by giving them names, the single deck chassis were named after animals, ranging in size from the 20–23-seat Leveret, then the 26–30-seat Lioness, the 32–36-seat Lion and finally the 38-seat Leopard, the double-deck on the other-hand adopted the mythical name Leviathan, designed for up to 48 seats, the same as the NS. Pneumatic tyre development for commercial vehicles was in its early stages and so although the single-deckers were designed for these, standard equipment for the Leviathan was six solid rubber tyres, two on the front axle and four on the back. The Leviathan was not the worst seller in the range (Leverets sold around 40 and there were two Leopards sold) most entered service fitted with covered tops, but unlike AEC with its captive market within the Underground Group, Leyland had to sell against competitors, and around sixty Leviathans were sold into 1927, most to municipal operators in Lancashire and Cheshire, with the largest private-sector operator being Crosville. The majority of the United Kingdom's electric tramways had come into being about a quarter of a century earlier, and the cost of maintenance of track and the surrounding highway, as well as the cost of maintaining the overhead wiring and the generation, transmission & substation network was impacting on profitability, although the majority of tramways were owned by local councils, some were in the private sector, and although sale of electricity to domestic consumers was beginning to develop as a profit centre, the inflexibility of operation made providing new or extended routes expensive, and on-road boarding began to be seen as obstructive of other road traffic and increasingly dangerous, and although the tramcar was in general a durable vehicle and capable of much re-engineering, standards varied and some networks were by 1925 thoroughly worn out. During 1925–26 Guy Motors and Karrier, the motor-vehicle subsidiary of the Clayton Engineering company of Huddersfield, promoted the six-wheel double-deck bus as the answer to those seeking to replace the double-deck tram. Unlike the Leviathan or the NS they ran as standard on pneumatic tyres, with two such at the end of all three axles, and at up to 30 ft long, where local construction regulations permitted (there were none nationally at the time; rules were set by local councils, watch-committees or, in London, the Metropolitan Police) passenger capacity could equal or exceed that of double deck trams. Other builders, AEC in particular (at the time in a collaboration deal with Daimler Company) followed-suit, getting the drawing offices to stretch existing buses into three-axle versions. Leyland, in particular, thought differently, and with the Lion becoming the best-selling single deck bus and coach in Britain, the "long Lion" from early 1926 proving particularly successful, almost 3,000 Lions and Lionesses (which differed only in driving position) sold by the end of the L-series three-year run, returning Leyland to profitability after catastrophic losses in the early 1920s Leyland's chairman Henry Spurrier (the second) decided to recruit design talent to give Leyland not just a temporary advantage but long-term technical and sales supremacy. He appointed G.J. "John" Rackham in the summer of 1926 as Leyland's chief engineer and commissioned from him a complete new product range, to start with a new double-deck bus. He did this because AEC now had enough capacity to offer a 420-series double-deck, like the NS but with a more conventional sliding-mesh gearbox, on general sale, which with AEC's ability to loss-lead on price given its large guaranteed London orders would spell the death of the Leviathan and also because of the threat from the promoters of big six wheelers. Rackham had worked for AEC in the pre-World War I period. He was involved in the design of London General's B-Type bus, under Frank Searle and then George Green; during World War I, he and Green worked on the Tank along with other gifted engineers such as Walter Wilson, after the war he had moved to the United States and under Green had been chief designer for John Hertz' Yellow Coach Company, one of the leading bus-builders in the States, Rackham, under Green's direction had evolved a range of fast, relatively light chassis with powerful engines and a trademark of frames gracefully swept with elegantly varying side-member depth, the Y and Z models also had off-set under-slung worm rear-axles and six-cylinder overhead-camshaft (OHC) petrol engines, OHC was not generally known in UK buses at the time and six-cylinder engines likewise. The only known Yellow Coach imported into the UK was fitted out in 1927 as a directors' saloon, for the use of Lord Ashfield and other directors of the Underground group, it was a luxurious mobile boardroom and pictures of it (inside and out) are available on the London Transport Museum website. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Leyland Titan (front-engined double-decker)」の詳細全文を読む スポンサード リンク
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