Multiple_working

Multiple working

Multiple working

Several locomotives running with a single driver

This article is about UK train operations specifically. For other uses, see Multiple-unit train control.

On the UK rail network, multiple working is where two or more traction units (locomotives, diesel multiple units or electric multiple units) are coupled together in such a way that they are all under the control of one driver (multiple-unit train control).

Blue Star multiple working equipment on a Class 40 locomotive
A Class 73 and a Class 33 locomotive being coupled for multiple working

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.

Many main-line diesel-electric and hydraulic locomotives are capable of running in multiples of up to three under the control of one driver

— British Railways Diesel Traction Manual for Enginemen, [1]

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 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.

More information Coupling code, System ...

Multiple units

Main article: Multiple unit

First-generation

Class 153 and Class 150 working in multiple

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.[4] However, because of damage to mechanical transmissions caused by improper gear selection on coupled hydraulic units, the Class 127 units had their coupling code changed from Blue Square to Red Triangle, which differed from Blue Square in name only and was unrelated to an earlier Red Triangle code used for the Derby Lightweight hydraulics.[5]

First-generation DMU coupling codes:

More information Coupling code, Class ...

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[6] 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, 222, 350, 360, 375, 376, 377, 390,[7] 700 and 710s while Scharfenbergs were fitted to Class 175[8] and 180s.[9] Franchise changes and stock reallocation means that many train operating companies use fleets with a number of incompatible multiple working systems.

See also

References and sources

References

  1. [1]
    British Railways Diesel Traction Manual for Enginemen. British Transport Commission. 1962. p. 184.
  2. [2]
    US Loco MU Control Archived 1 February 2008 at the Wayback Machine
  3. [3]
    "Built in the 1960s… rebuilt for the 21st century". Rail. Retrieved 20 January 2020.
  4. [4]
    The Railcar Association. "Class 127 DMU Interiors". Retrieved 12 August 2023.
  5. [5]
    The Railcar Association. "Class 127 DMU Description". Retrieved 12 August 2023.
  6. [6]
    Class 172 Archived 13 June 2020 at the Wayback Machine Angel Trains
  7. [7]
    Class 390 Archived 4 March 2016 at the Wayback Machine Angel Trains
  8. [8]
    Class 175 Archived 4 March 2016 at the Wayback Machine Angel Trains
  9. [9]
    Class 180 Angel Trains

Sources

  • Williams, Alan; Percival, David (1977). British Railways Locomotives and Multiple Units including Preserved Locomotives 1977. Shepperton: Ian Allan. ISBN 0-7110-0751-9.
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