Multiple working
From Wikipedia, the free encyclopedia
Multiple working is a term used on the UK rail network to describe the practice of having more than one diesel or electric locomotive hauling a train under the control of one driver.
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[edit] Terminology
| “ | Many main-line diesel-electric and hydraulic locomotives are capable of running in multiples of up to three under the control of one driver | ” |
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—British Railways Diesel Traction Manual for Enginemen, [1] |
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Multiple Working is the term used in the UK where more than one operational diesel or electric locomotive is coupled together under the control of one driver. The term can also apply when diesel or electric multiple unit trains are coupled together and also under the control of one driver. 'In tandem' is the term usually used in the UK when more than one diesel or electric locomotive is hauling a single train and under the control of a driver on each locomotive.
If the front locomotive of a pair in multiple has failed the driver can still control the rear locomotive for as long as air and electricity supplies are available on the failed locomotive.
[edit] Locomotives
In the early days of diesel locomotives, locomotives worked within their class (ie, two locomotives of the same class could work together but not with other classes). Locomotives from different manufacturers had varying methods of controlling engines or braking systems. If a train required more than one locomotive, an additional driver was needed, at extra expense.
Since then, locomotives have been built to work with other locomotives in the same code or system. Similar systems are assigned a coupling code, which is normally indicated on the front of the locomotive.
Early diesels were also fitted with communicating doors in the nose which allowed the secondman to access the train heating boiler of the rearmost locomotive. The doors actually saw little use and, as they frequently caused draughts in the cab, many of them were later welded shut.
In North America, the Association of American Railroads sets technical standards and a high level of standardization has been achieved. Although there are similar bodies in Europe they seem to have been far less successful.
| Code or system | Class of locomotives |
| AAR System [2] | Class 59, Class 66 and Class 67. |
| Blue Star Coupling Code | Class 15, Class 17 (Nos D8588-8616),Class 20, Class 24, Class 25, Class 26, Class 27, Class 31/1, Class 33, Class 37, Class 40, Class 44, Class 45 and Class 46, Class 73 (under diesel power only). |
| Green Circle Coupling Code | Some Class 47. |
| Orange Square Coupling Code | Class 50. |
| Red Circle Coupling Code | Class 16, Class 21, Class 28, Class 29, Class 31/0. |
| Red Diamond Coupling Code | Class 17, Class 56, Class 58. |
| White Diamond Coupling Code | Class 22, Class 41, Class 42, Class 43, |
| SR System | Class 33/1, Class 73, Mark One Electric Multiple Units. |
| AC electric locomotives | Class 87, some Class 86s. |
| Within own class only | Class 43 InterCity 125, Class 60. |
[edit] Multiple units
[edit] First-generation
First-generation diesel multiple units had the additional problem of differing types of transmission. For instance, a Class 127 unit (hydraulic transmission) could be required to work in multiple with a Class 112 unit (mechanical transmission). For this reason, the drive selector on the Class 127 was fitted with positions marked "D, 3, 2, 1" to change the gears when working in formation with vehicles with mechanical transmission.[3]
First-generation DMU coupling codes:
| Coupling code | Class |
|---|---|
| Blue square | Most units with mechanical transmission |
| Orange star | Most units with hydraulic transmission |
| Yellow diamond | Derby Lightweight (mechanical transmission) |
| Red triangle | Derby Lightweight (hydraulic transmission) |
| White circle | Class 126 |
[edit] Second-generation
Many types of second-generation DMUs are compatible with each other and may work in multiple. These include classes 150, 153, 155, 156, 158, 159 and (with certain restrictions) 170.
[edit] References and Sources
[edit] References
- ^ (1962) British Railways Diesel Traction Manual for Enginemen. British Transport Commission, p184.
- ^ US Loco MU Control
- ^ The Railcar Association. Description of the Class 127s. Retrieved on 2007-08-22.
[edit] Sources
- Williams, Alan; Percival, David (1977). British Railways Locomotives and Multiple Units including Preserved Locomotives 1977. Shepperton: Ian Allen Ltd. ISBN 0 7110 0751 9.
