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The British Rail Class 303 electric multiple units, also known as "Blue Train" units, were introduced in 1960 for the electrification of the North Clyde and the Cathcart Circle lines in Strathclyde. They were initially classified as AM3 units before the introduction of the TOPS classification system, and were the dominant EMU on the Glasgow suburban railway network for over 25 years before being progressively phased out by newer rolling stock. The final units were withdrawn from service in 2002. The fleet's lifespan was 42 years. The units were later used on the Inverclyde and Argyle lines of the Glasgow suburban railway network as various electrification schemes came to fruition. ==Description== Ninety-one 3-car units were built by Pressed Steel at Linwood near Paisley, from 1959–1961, although they were not introduced into service until 1960.〔Gillham (1988), Chapter 19: ''25 kV for Glasgow''.〕 A further 19 near-identical Class 311 units were built in 1967 following the Inverclyde electrification, although these units were built by Cravens in Sheffield.〔 When new, the units were initially numbered in the range 001-091, but were later renumbered to 303 001-091 when TOPS was introduced. Each unit consisted of 3-cars coupled together in a semi-permanent formation, and up to four sets could be operated in multiple to form up to a 12-car formation. Although 6-car formations were frequently operated, 9-car formations were operated occasionally. 12-car formations were usually only seen as a result of train failures or ECS workings to the depots at Shields Road or Hyndland. The two outer carriages of each unit were driving trailers, with an intermediate motor coach containing the motor bogies and electrical equipment. Units operated from the standard 25 kV alternating current (AC) overhead power lines system, with power collection via a Stone Faiveley AMBR pantograph on the motor coach. The technical description of the formation is DTSO+MBSO+BDTSO. Individual vehicle numbers are shown below. * 75566-75600 and 75746-75801 - DTSO * 61481-61515 and 61812-61867 - MBSO * 75601-75635 and 75802-75857 - BDTSO The class was built in two batches; units 303001-035 were built 1959-60 (nominally for the North Clyde Line) and units 303036-091 were built 1960-61 (nominally for the Cathcart Circle Lines). In practice, when built, the North Clyde lines required the majority of the units. There was no electrified connection between the two networks until late in the life of the trains, and thus transfers between the two halves of the system, performed quite regularly, were dragged by locomotives via the Shields Road-High Street line. As the Class 303 were air braked, and most diesel locomotives of the early era were vacuum braked, a few Class 20 diesels were fitted with air brake connections for this, although when the Class 303 were new there were still a few former Caledonian Railway 4-4-0 steam locomotives in stock with the Westinghouse air brake, which were used for the transfers, and for delivering the units from their factory in Paisley. Based on the Mark 1 bodyshell design, the Class 303 units utilised electrical gear made by Metropolitan-Vickers (Metrovick). The Class 303s were originally dual voltage - parts of the North Clyde Line and Cathcart Circle electrification was limited to 6.25 kV (rather than the standard 25 kV arrangement) due to limitations in insulation technology, although this feature was rendered redundant as 25 kV was eventually standardised across the entire line.〔 Following a series of transformer explosions, caused by defects in the 6.25 kV/25 kV changeover equipment, the entire stock of Class 303s had to be hastily withdrawn from service after only a few weeks' service.〔 The old steam-operated service was temporarily reinstated whilst urgent modifications were made. This also delayed the handing over of the Cathcart Circle service to electric operation. The units had many features which made them state of the art at the time of their introduction. This included the use of pneumatically operated sliding passenger doors (the only Mark 1 based EMU to use this feature), with passenger-operated door opening buttons. In practice, the doors were usually operated by the train guard (later driver, after modification for driver-only operation). When built, the driving cabs had distinctive wrap-around front windows, although these were replaced by flat, toughened glass in the 1970s to better protect drivers following some incidents of stone-throwing vandalism. Glass partitions behind the cabs allowed passengers in the front and rearmost carriages to see the drivers' view of the track. This was particularly appreciated in the scenic riverside areas around Craigendoran and Helensburgh. Following the electrification of the lines from to Gourock and Wemyss Bay in 1967, the Class 303s started to be used interchangeably with the almost identical new Class 311s. The interiors of the Class 303s were fitted with tungsten light bulbs whilst the Class 311s had fluorescent lighting. The Class 303 fleet were nicknamed the "Blue Trains" upon their introduction, owing to the striking Caledonian Blue livery.〔 This was later changed to the standard BR Blue, quickly superseded by BR Blue/Grey livery in the late 1960s and early 1970s.〔 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「British Rail Class 303」の詳細全文を読む スポンサード リンク
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