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A merry-go-round train, often abbreviated to MGR, is a block train of hopper wagons which both loads and unloads its cargo while moving. In the United Kingdom, they are most commonly coal trains delivering to power stations. These trains were introduced in the 1960s, and were one of the few innovations of the Beeching axe, along with investment from the CEGB (Central Electricity Generating Board) and the N.C.B. (National Coal Board) into new power stations and loading facilities. West Burton Power Station was used as a testing ground for the MGR system〔Railway Magazine 1965 July p 388〕 but the first power station to receive its coal by MGR was Cockenzie in Scotland in 1966.〔Railway Magazine 1965 March p172〕 It was estimated at the time that the 80 MGR hoppers needed to feed Cockenzie would replace up to 1500 conventional wagons.〔Railway Magazine 1965 April p197〕 A 1.2 GW power station, such as Cockenzie, receives up to 3 million tons of coal a year, whereas a larger 2 GW plant, like West Burton, up to 5 million tons per year. By the end of 1966 there were about 900 wagons carrying 53,000 tons a week to four power stations.〔Modern Railways June 1967 p. 322〕 Power stations that were built to handle the new MGR traffic were Aberthaw, Drax, Didcot, Eggborough, Ferrybridge C,〔Modern Railways October 1966 p. 521〕 Fiddlers Ferry and Ratcliffe, all of which, apart from Didcot are still open for traffic. Many of the older power stations were gradually converted to MGR operation. == The MGR Hopper Wagons == There were 11,162 MGR hoppers built. The numbering ranges were 350000-359571, 365000-366129 and 368000-368459 The two prototype wagons, 350000 and 350001, were built at Darlington works in 1964 and 1965 respectively, following which several large batches were constructed at the nearby Shildon works. With the exceptions of the two prototypes built at Darlington and the 160 wagons built at Ashford, all 10,702 HAA wagons and 460 HDA wagons were built there. Most of the early wagons (up to 355396) were originally lettered with B prefix numbers but these were later removed. While the majority of the wagons were built as HAAs, the final batch (built in 1982 as 368000-368459) were coded as HDA to indicate their ability to operate at up to 60 mph when empty instead of the standard 45 mph. This was achieved through modifcations to the design of the brakes. Another variation, which did not initially result in a change of TOPS code, was the fitting of top canopies to increase the load volume. Many of the early wagons had these but then lost them and for some years canopied hoppers were only common in Scotland. When MGR services were first introduced, British Rail designed an all-new wagon with air brakes and a capacity for 33 tonnes of pulverised coal. The prototype was a 32-ton unit and was built at Darlington and tested in 1964.〔Railway Magazine 1965 April p197〕 Before the introduction of TOPS these wagons were referred to by the telegraphic code name "HOP AB 33", this was an abbreviation of Hopper Air Brake 33 tonne. With the coming of privatisation to Britain's railways, new wagon types have been introduced by EWS (HTA), GBRf (HYA), Freightliner Heavy Haul (HHA and HXA) and Jarvis Fastline (IIA). These new wagons have increased tonnage and air-operated doors that do away with the need for the "Dalek" release mechanism at the power station end of the trip. 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「Merry-go-round train」の詳細全文を読む スポンサード リンク
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