On the UK rail network, multiple working is where two or more traction units (locomotives,

diesel multiple-unit A diesel multiple unit or DMU is a multiple-unit train powered by on-board diesel engines. A DMU requires no separate locomotive, as the engines are incorporated into one or more of the carriages. Diesel-powered single-unit railcars are also ...

s or

electric multiple-unit An electric multiple unit or EMU is a multiple-unit train consisting of self-propelled carriages using electricity as the motive power. An EMU requires no separate locomotive, as electric traction motors are incorporated within one or a number ...

s) are coupled together in such a way that they are all under the control of one driver (

multiple-unit train control Multiple-unit train control, sometimes abbreviated to multiple-unit or MU, is a method of simultaneously controlling all the traction equipment in a train from a single location—whether it is a multiple unit comprising a number of self-powered ...

). 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. In tandem is when more than one diesel or electric locomotive are hauling a single train and under the control of a driver on each locomotive.

Locomotives

In the early days of diesel locomotives in the 1960s, locomotives worked within their class (i.e. 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 {{unreferenced, date=August 2017 A secondman or second man is a railway employee who assists the driver of a train. For this reason the term driver's assistant is also used. In this role, the second man could learn the duties of the driver and on p ...

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.

Multiple units

First-generation

First-generation diesel multiple units had the additional problem of differing types of

transmission Transmission may refer to: Medicine, science and technology * Power transmission ** Electric power transmission ** Propulsion transmission, technology allowing controlled application of power *** Automatic transmission *** Manual transmission *** ...

. For instance, a Class 127 unit ( hydraulic transmission) could be required to work in multiple with a Class 112 unit (

mechanical transmission Propulsion transmission is the mode of transmitting and controlling propulsion power of a machine. The term ''transmission'' properly refers to the whole drivetrain, including clutch, gearbox, prop shaft (for rear-wheel drive vehicles), differ ...

). 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. First-generation DMU coupling codes:

Second-generation

Most second-generation units built by

British Rail British Railways (BR), which from 1965 traded as British Rail, was a state-owned company that operated most of the overground rail transport in Great Britain from 1948 to 1997. It was formed from the nationalisation of the Big Four British rai ...

were designed to use the BSI multiple working system, including members of the 14x Pacer and 15x Sprinter families. Some post-privatisation trains such as the Class 168,

170 Year 170 ( CLXX) was a common year starting on Sunday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Clarus and Cornelius (or, less frequently, year 923 ''Ab urbe condita ...

and 172s were fitted with BSI couplers enabling them to operate in multiple with older stock, while other incompatible systems emerged. Examples included Dellner-couplers fitted to Class 171,

220 __NOTOC__ Year 220 ( CCXX) was a leap year starting on Saturday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Antonius and Eutychianus (or, less frequently, year 973 '' ...

221 __NOTOC__ Year 221 (Roman numerals, CCXXI) was a common year starting on Monday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Gratus and Vitellius (or, less frequently, ...

222 __NOTOC__ Year 222 ( CCXXII) was a common year starting on Tuesday (link will display the full calendar) of the Julian calendar. In the Roman Empire, it was known as the Year of the Consulship of Antoninus and Severus (or, less frequently, ye ...

350 __NOTOC__ Year 350 (Roman numerals, CCCL) was a common year starting on Monday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Sergius and Nigrinianus (or, less frequentl ...

360 360 may refer to: * 360 (number) * 360 AD, a year * 360 BC, a year * 360 degrees, a circle Businesses and organizations * 360 Architecture, an American architectural design firm * Ngong Ping 360, a tourism project in Lantau Island, Hong Kong * Q ...

375 __NOTOC__ Year 375 (Roman numerals, CCCLXXV) was a common year starting on Thursday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year after the Consulship of Augustus and Equitius (or, less fre ...

376 __NOTOC__ Year 376 (Roman numerals, CCCLXXVI) was a leap year starting on Friday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Valens and Augustus (or, less frequently, ...

377 __NOTOC__ Year 377 ( CCCLXXVII) was a common year starting on Sunday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Augustus and Merobaudes (or, less frequently, year 11 ...

390 __NOTOC__ Year 390 (Roman numerals, CCCXC) was a common year starting on Tuesday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Augustus and Neoterius (or, less frequen ...

700 The denomination 700 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years. Events By place Byzantine Empire * Avar and Slavic tribes conq ...

and 710s while Scharfenbergs were fitted to Class 175 and 180s.Class 180
Angel Trains Franchise changes and stock reallocation means that many

train operating companies A train operating company (TOC) is a business operating passenger trains on the railway system of Great Britain under the collective National Rail brand. TOCs have existed since the privatisation of the network under the Railways Act 1993. The ...

use fleets with a number of incompatible multiple working systems.

References and sources

References

Sources

* {{DEFAULTSORT:Multiple Working Rail transport operations Rail transport in the United Kingdom