| 词条 | British United Traction DMUs | ||||||||||||||||
| 释义 |
The British United Traction produced various diesel multiple units. Early British Railways DMUs{{Infobox EMU| name = British Rail British United Traction | image = | imagesize = 300px | caption = | background = #012545 | manufacturer = | family = | formation = 2-3 car units| numberbuilt = 11 | service = 1953 - 1962 | weight = | capacity = | maxspeed = | gauge = | brakes = | engine = 9.6-litre, 125 bhp (93 kW) AEC.--------- 9.8-litre, 125 bhp (93 kW) Leyland 11.3-litre, 150 bhp (110 kW) AEC. ------- 11.1-litre, 150 bhp (110 kW) Leyland. 15-litre, 230 bhp (170 kW) Leyland/Albion | operator = British Rail }} BUT produced 11 lightweight diesel multiple unit vehicles for British Railways during the 1950s, numbered 79740–79750 with an M at the beginning. the first units finished in 1952. When they finished being reviewed by British Railways, British Railways took them into stock in 1953. They were of three different types of rail cars (DMS, DMBS (containing a compartment for the guard) and TS), and could be made up into two- or three-car units. The first units were fitted with skirts covering their underframes and wheels; they were later removed. They were not very successful so they were all withdrawn by 1962, so never received TOPS classification.
First-generation DMUsBUT also built the powertrain for the majority of British Rail 'first generation' DMUs. EnginesThe engines mainly had six horizontal cylinders and were made in several sizes:
AEC and Leyland engines were those designed and built by the respective companies and were not badge engineered except for BUT badges. Six- and eight-cylinder Rolls Royce diesel engines were also used. The first post-war lightweight DMUs 1954-1969 are reputed to have had pre-war Leyland 8.6-litre horizontal diesel engines fitted. It would be nice to have this confirmed. Turbo-charged versions of the {{convert|11.3|L|cuin|adj=on}} and {{convert|15|L|cuin|adj=on}} engines were available, boosting the power outputs to {{convert|200|bhp|abbr=on}} and {{convert|275|bhp|abbr=on}} respectively. The turbo-charged versions were not used by British Railways, but they were used by Ulster Transport Authority. Some engines were badged AEC, some Leyland and some Leyland-Albion. Engines were genuine AEC or Leyland, each type carrying B.U.T. badges. Transmission systemsMost units had Standard Mechanical Transmission. This comprised a fluid coupling, a freewheel and a four-speed epicyclic pre-selector gearbox. The freewheel facilitated gear-changing and also had an important safety function. If an engine seized, the freewheel would disengage and give protection against transmission damage and possible derailment. A small number of units had hydraulic transmission, using a torque converter. Coupling codesThe level of standardisation achieved with BR's first generation DMUs was much higher than it is with modern DMUs. All had side buffers, screw couplings and vacuum brakes and the majority had the standard Blue Square coupling code system for control of engine speed and gear-changing. There were some units with non-standard coupling codes but they were a small minority. The coupling codes were:
Non-BUT enginesSome first generation DMUs were fitted with Rolls-Royce engines. Three types were used:
The six-cylinder engines usually drove through standard mechanical transmissions, but the eight-cylinder engines were usually coupled to Twin-disc (Rolls-Royce) torque converters. Mixed runningRolls-Royce devised a system which enabled DMUs with mechanical and hydraulic transmissions to work together. The British Rail Class 127 units were fitted with this system and given the standard Blue Square coupling code, instead of the Orange Star code given to the British Rail Class 125 units. There was a gear-change lever (marked D-3-2-1) on the driver's desk and it worked as follows:
It was a good idea but it created problems in practice. If the mechanical stock was at the back, the driver might forget to change gear, and this could lead to gearbox damage. In 1969 (after a serious accident in 1968) the Class 127s were re-labelled with the (then disused) Red Triangle coupling code, and mixed running was discontinued. See also
External links
The Railcar Website was refurbished during 2011. {{British Rail DMU}} 1 : British Rail diesel multiple units |
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