Class 31 (Brush Traction 1,470hp Type 2 Diesel-Electric)

The popular Class 31 is the last surviving Type 2 diesel locomotive in national rail service with a small number soldering on today, mainly working for Network Rail hauling engineering trains. Originally they were known as the Class 30 and were amongst the earliest diesel locomotives to enter service with British Railways following the decision to replace steam. When first designed they had just 2 windows on the cab ends with a look similar to the likes of the Class 21 but the design was amended to have 3 windows due to the need to fit gangway doors. [1] When delivered the locomotives had a BR green livery with horizontal lines to aid the impression of speed (see photo of D5581 below).

Information
Number built: 263
Built: 1957-62
Builder: Brush Traction
Wheel Arrangement: A1A-A1A
Engine: Mirrlees JVS12T
later changed to English Electric 12SVT diesel
Power: 1, 470 hp (1, 100 kW)

The original Mirrlees JVS12T engines gave BR a lot of trouble as they began to develop metal fatigue after just a few years service. It is thought that uprating the engines may have been to blame as the originally rated engines did not develop as many faults. The original pilot-scheme locomotives were rated at 1, 250hp but later production batch locomotives were uprated to 1, 365 hp and beyond. One was even uprated to 2, 000hp and became a Type 4!


Eventually the decision was made to give the entire class more reliable English Electric powerplants instead in the mid 1960s [2] and so they became the Class 31. The Class 31 has the unusual A1A-A1A wheel arrangement which means the middle axle in each bogie is unpowered.

As true mixed traffic locomotives Class 31s could be found on regional and secondary passenger services, freights and engineering trains and have survived into the privatised era. Nowadays they are mainly seen on spot hires and engineering trains [3]. Less than a handful remain in mainline service but 26 have been preserved.

Sub-classDetails
31/0 Original pilot-scheme batch of 20, non-standard control equipment
31/1 Main production variant
31/4 With Electric Train Heating (ETH)
31/5 Former 31/4s with ETH isolated
31/6 Wired for ETH but without equipment

Preserved 5580 at Kidderminster SVR

Preserved 31 270 in Regional Railways livery at Rowsley South

Network Rail 31 233 at Derby

DCR 31 452 at Bewdley

D5581 at Chinnor showing the original BR green livery

Although numbered 31 018 this was the first of the class built, preserved at the NRM



[1] David Lawrence, British Rail Designed 1948-97 (Ian Allan, 2016) p. 124
[2] Brian Haresnape, Production Diesel-Electrics Types 1-3 (Ian Allan, 1983) p. 48
[3] Colin J Marsden, Traction Recognition (Second Edition) (Ian Allan, 2009) p. 20