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 num ...
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. 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 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 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,
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
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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,
360,
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,
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 use fleets with a number of incompatible multiple working systems.
See also
* 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 ...
References and sources
References
Sources
*
{{DEFAULTSORT:Multiple Working
Rail transport operations
Rail transport in the United Kingdom