Class 37

Class 37
Name	Class 37
Powertype	Diesel-electric
Builder	English Electric
Builddate	1960–1965
Totalproduction	309
Wheelarrangement	Co-Co
Locale	United Kingdom

Class 37

Class 37 were a class of diesel-electric locomotives built by English Electric between 1960 and 1965 for British Railways. Widely used across the West Coast Main Line, Great Western Main Line, East Coast Main Line, and secondary routes in Scotland and Wales, they became noted for their distinctive exhaust note and longevity. The class featured versatile tractive effort suitable for passenger expresses, freight trains, and engineering workings, and many examples passed into service with Network Rail, Direct Rail Services, Serco, and private preservation groups.

Overview

Designed during the Modernisation Plan (British Railways) era, the machines were part of a family that included earlier English Electric Type 4 designs and paralleled developments such as the Class 40 and Class 47. They entered service amid reorganisation tied to the Beeching cuts and the shift from steam to diesel traction across the British Transport Commission network. The class saw allocations on principal routes serving London Euston, Birmingham New Street, Glasgow Central, Cardiff Central, and branch termini including Penzance and Aberdeen. During their careers they interacted operationally with rolling stock such as the Mark 1 coach, Mark 2 coach, and InterCity 125 sets.

Design and Development

The design originated from requirements set by the British Transport Commission and was influenced by prototypes including the Deltic and export models used in Australia and New Zealand. English Electric combined its 12-cylinder 18SVT engine with DC generator technology employed on locomotives delivered to operators like Cleveland Transit Authority and firms such as National Coal Board. Early production involved trials at Crewe Works and acceleration tests on the West Coast Main Line under supervision by engineers associated with Robert Riddles and design leads seconded from Hawker Siddeley affiliates. The bodyshell, with the trademark long nose and short hood, was built to withstand remit from Ministry of Transport standards and to simplify maintenance at depots including Crewe South and Kingmoor.

Technical Specifications

Powered by an English Electric 12CSVT or 12SVT engine rated around 1,750 hp, the locomotives used DC traction motors and a Co-Co wheel arrangement with axle load compatible with routes controlled by the Railway Clearing House gauges. Key equipment included multiple-unit control compatible with contemporaries such as Class 40 and Class 47, steam heating boilers for Mk1 and Mk2 coaching stock, and later retrofits with electric train heating akin to systems installed on Class 86. Brake systems conformed to BR Blue Star multiple working practice and preserved units sometimes display fittings from overhauls performed at Doncaster Works and Crewe Works. The basic dimensions, weight, tractive effort curves, and gearing permitted top speeds commonly set at 80 mph for mixed-traffic duties, while axle load classifications allowed operation over secondary routes such as the Settle–Carlisle line.

Operational History

Upon introduction they replaced steam classes including Britannia class and Clan class locomotives on express workings. During the 1960s and 1970s the class hauled named trains serving The Royal Scot and local expresses out of Euston and Paddington connections to Bristol Temple Meads. In freight service they handled flows from Felixstowe and Immingham and moved coal to power stations linked with National Power and British Energy distribution points. Several were allocated to Scottish regions for duties to Inverness and the Highland Main Line, occasionally working charter special trains for organisations such as The Railway Touring Company and Ian Allan Publishing. Their long careers included incidents investigated by bodies like the Rail Accident Investigation Branch and notable appearances at events including the Keighley and Worth Valley Railway galas and the Railfest exhibition.

Variants and Modifications

Later sub-classes and modifications produced variations in power, gearing, and train heating: adaptations comparable to retrofits on Class 47 included electric train heating conversions and re-engining programmes reflecting work by Brush Traction and Ruston. Some units were rebuilt with reconfigured cabs for one-man operation and fitted with multiple working jumpers to operate with Class 56 and Class 66 locomotives on freight diagrams. Specialized conversions served Network Rail test trains, EWS (later DB Cargo UK) freight diagrams, and nuclear flask movements for Direct Rail Services. Numerous locomotives received unique liveries for operators including Virgin Trains, GWR, Arriva Trains Wales, ScotRail, FirstGroup and short-term leases to continental operators for trials.

Preservation and Legacy

A substantial number of locomotives were withdrawn from mainline service and preserved on heritage railways such as the North Yorkshire Moors Railway, Midland Railway – Butterley, Severn Valley Railway, and Great Central Railway. Preservation groups and owners including The Class 37 Locomotive Group, private owners, and corporate custodians maintain operational examples for gala events, mainline charters under Network Rail regulations, and film work connected with studios like BBC Television and ITV. The class’ sound and reliability have secured a place in popular culture with appearances in documentaries and modelling circles tied to manufacturers such as Hornby and Bachmann. Several preserved units carry historical liveries commemorating runs for British Rail and regional operators, ensuring ongoing public engagement and technical study by institutions like the National Railway Museum.

Category:Diesel locomotives of the United Kingdom