British Rail Class 311

The British Rail Class 311 alternating current (AC) electric multiple units (EMU) were built by Cravens at Sheffield in 1967. They were intended for use on the line from Glasgow Central to Gourock and Wemyss Bay, which was electrified in 1967.

British Rail Class 311
311092 at Glasgow Central
In service1967 - 1990[1]
ManufacturerCravens[1]
Order no.
  • 30767 (DTSO)
  • 30768 (MBSO)
  • 30769 (BDTSO)[1]
Built atCravens Sheffield
Family nameBR First Generation (Mark 1)
Constructed1967[2]
Entered service1967
Number built19
Formation3 cars per trainset:
DTSO+MBSO+BDTSO[2]
Diagram
  • ED211 (MBS)
  • EE214 (DTS)
  • EF212 (BDTS)[3]
Design codeAM11
Fleet numbers
  • 311092-311110 (sets)
  • 76403-76421 (DTSO)
  • 62163-62181 (MBSO)
  • 76422-76440 (BDTSO)[1]
Capacity
  • 236S (total)
  • 83S (DTSO)
  • 70S (MBSO)
  • 83S (BDTSO)[2][4]
Operator(s)British Rail
Depot(s)Glasgow Shields Road[2]
Specifications
Car body constructionSteel[3]
Train length199 ft 6 in (60.81 m)[4]
Car length
  • 63 ft 6 1⁄8 in (19.358 m) (MBSO)
  • 64 ft 0 in (19.498 m) (BDTSO, DTSO)[3]
Width9 ft 3 in (2.819 m)[3]
Height12 ft 8 in (3.861 m)[3]
DoorsDouble sliding leaf, pneumatic
Wheelbase46 ft 6 in (14.173 m)[3]
Maximum speed75 mph (121 km/h)[3]
Weight
  • 129 tonnes (127 long tons; 142 short tons) (total)
  • 34.4 t (33.9 long tons; 37.9 short tons) (DTSO)
  • 56.4 t (55.5 long tons; 62.2 short tons) (MBSO)
  • 38.4 t (37.8 long tons; 42.3 short tons) (BDTSO)[2]
Traction motors4 × AEI 221 hp (165 kW)[2]
Power output890 hp (660 kW)
Train heatingElectric[3]
Electric system(s)25 kV 50 Hz AC OHLE
Current collection methodPantograph
UIC classification2'2'+Bo'Bo'+2'2'
Bogies
  • Gresley ED11 (MBSO)
  • Gresley ET11 (BDTSO, DTSO)[3]
Braking system(s)Air (Auto/EP)[4]
Safety system(s)AWS[3]
Coupling systemBuckeye[4]
Multiple workingWithin Class and Class 303[4]
Track gauge1,435 mm (4 ft 8 1⁄2 in) standard gauge

Appearance

Outwardly, the units were virtually identical to the earlier Class 303 units built in 1960. The interiors were also very similar, including the panoramic full forward passenger view through the glass-walled driving cabs, although the Class 311s had fluorescent lighting (unlike the Class 303s which were fitted with tungsten filament bulbs). The larger fleet of class 303 units had been built by Pressed Steel at their factory in Linwood, Paisley. By the time the Class 311 were required, Pressed Steel no longer built railway carriages, so Cravens of Sheffield worked to the same original drawings, updated at a few points, to build the trains.

Along with the Class 303s, the wrap-around driving cab windows were replaced with flat, toughened glass in the 1970s to give better protection to drivers in the event of attacks by stone-throwing vandals.

Construction

19 units were built, initially classified as AM11 units, and numbered 092-110. This was later changed to Class 311 under the TOPS system, and the units were renumbered 311092-110. Each unit was formed of three carriages; two outer driving trailers and an intermediate motor coach. The technical description of the formation was BDTCOL+MBSO+DTSO. Individual carriages were numbered as follows:

  • 76403-76421 - BDTCOL
  • 62163-62181 - MBSO
  • 76422-76440 - DTSO

Operations

The units were built to operate services on the newly electrified routes from Glasgow Central to Gourock and to Wemyss Bay; now known as the Gourock and Wemyss Bay branches of the Inverclyde Line.

In practice, the Class 311s operated almost interchangeably with the Class 303s. The units could be found in service across the Glasgow electrified suburban network (north and south of the Clyde, and as far south as Ayr).

Consideration was given to upgrading 11 of the units for the Ayr line electrification until it was found to be cheaper to buy 21 of the new Class 318 units and the plan was cancelled.

Withdrawal

Being a much smaller and unrefurbished fleet, the Class 311s were replaced (in the 1990s) earlier than the Class 303s.

After being withdrawn from normal traffic, two units, nos. 311103/104 were transferred to departmental duties as Class 936 sandite units, nos. 936103/104. These lasted in service until 1999, when they were withdrawn. They were not scrapped immediately as Railtrack was anxious to ensure that one of the units was preserved. In 2002, Railtrack donated one of the units to the Summerlee Heritage Park museum in Coatbridge. The other unit was scrapped in 2003.

One of the driving coaches on the unit donated to Summerlee was subsequently scrapped.

Preservation

This unit was the former Class 936 sandite unit, no. 936103, formed of 977844+977845+977846.

In February 2017, work finally started on restoring the ex-British Rail Class 311 unit to its original condition.

References
  1. Longworth 2015, pp. 73, 139, 191–192
  2. Fox 1987, p. 56
  3. "Vehicle Diagram Book No.210 for Electrical Multiple Units (including A.P.T.)" (PDF). Barrowmore MRG. BRB Residuary Ltd. ED211, EE214, EF212. Retrieved 22 February 2016.
  4. "Class 311". The Railway Centre. Archived from the original on 7 September 2008. Retrieved 22 February 2016.

Sources
  • Fox, Peter (1987). Multiple Unit Pocket Book. British Railways Pocket Book No.2 (Summer/Autumn 1987 ed.). Platform 5 Publishing Ltd. ISBN 0906579740. OCLC 613347580.
  • Longworth, Hugh (2015). British Railways Electric Multiple Units to 1975. Oxford Publishing Co. ISBN 9780860936688. OCLC 923205678.

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