Locomotives / Train Sets

BR Class 37 (English Electric Type 3)

Diesel-Electric Locomotive

"Despite only five years in production, over 300 BR Class 37 locomotives were built with a notable number still in service today."

Entry Last Edited: 01/17/2024 | Content ©www.RailRoadJunction.net | The following text is exclusive to this site.
Specifications [+]
Built from 1960 until 1965 to the tune of 309 units, the BR Class 37 diesel-electric locomotive has been a regular operator along the British railways network. The type has been used in both people-hauling and freight-moving industries since inception though, with the increased reliance on Electric Multiple Units (EMUs), the series sees less and less focus today (2023). The design was manufactured by English Electric (therefore it is also known as the "English Electric Type 3") through its Vulcan Foundry as well as Robert Stephenson and Hawthorns.

Key operators of the Class 37 have been British Rail, Colas Rail, EWS, Direct Rail Services, Europhoenix, Locomotive Services Ltd, Rail Operations Group, and West Coast Railways. The BR Class 37 is also known by the names of "Growler" (due to its distinct engine noise), "Slugs", "Syphon", and "Tractor".

Aviation buffs will recognize the builder name of English Electric (EE) for its contributions to British aviation.

The general appearance of the locomotive was consistent with 1960s loco design - utilitarian to the core though not without some styling. The unit has a stepped driving compartment with short hood ahead with hinged, rectangular doors positioned at the loco sides for cabin access. This was repeated at both ends of the unit with the engine sat in between. The unit had an overall length of 61.5 feet with a beam of 8.10 feet and a height of 12.8 feet. Weight registered 112 tons (short).

Internally, the original loco was developed with a diesel-electric powerplant, driven by the English Electric 12CSVT as its prime mover installation with an EE822 main generator and EE911/5C auxiliary generator. The traction arrangement were English Electric DC traction sets. Complete output power was rated at 1,750 horsepower with a 55,500lbf traction effort maximum possible. The braking system was initially (Class 37/0) steam-based with a switch to Electric Train Heat in the Class 37/4 subclass. The wheel configuration is Co'-Co' under the UIC standard.

In terms of performance, the locomotive could reach speeds between 80 and 90 miles-per-hour.

The BR Class 37 was produced in several notable marks. These were led by the original Class 37/0 models. Then followed the Class 37/3 mark which were given new bogies. The Class 37/4 was completely refurbished and rewired while utilizing Brush alternators and an Electric Train Supply (ETS). The Class 37/5 was similar in that they were refurbished / rewired but carried the Brush Traction alternator instead. Class 37/6 marked Class 37/5 models with ETS as well as RCH jumper cables added. The heavier Class 37/7 were refurbished / rewired and carried GEC G564AZ or Brush alternators. The Class 37/9 completed the list and, again, were refurbished / rewired units with Brush alternators and powered by either Mirrless MB275Tt or Ruston RK270Tt engines.

Of the 309 units built, 51 of the fleet were stationed out of Cardiff Canton followed by the 50 at Thornaby, and 47 from Landore. Additional units were seen throughout Britain, from Eastfield in the north to Stratford in the East.

Remaining in active service today (2023) with 67 total units of the original stock available, Direct Rail Services runs the largest fleet with 20 units in circulation. This is followed by the 11 operated by Colas Rail and the 11 by West Coast Railways - all other customers operating fewer than ten of the series.

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Specifications [ BR Class 37 (English Electric Type 3) ]

English Electric (Vulcan Foundry) / Robert Stephenson and Hawthorns - UK

United Kingdom
1960 - 1965
Production Run

309 units
Production Total
Train driver seating position graphic

Driver Position
18.8m | 61.5 ft
NOTE: May include length of entire train set
101,605 kg
(224,039 lb | 112 US Tons)
Locomotive power source graphical icon
Power Source
AS BUILT: 1 x English Electric 12CSVT with English Electric EE822 main generator and EE911/5C auxiliary; LATER: Brush BA1005A alternator with Brush BA606A auxiliary.
Engine / Drive Source
English Electric DC traction motor arrangement.
Traction Motor / Sets
1,750 hp
Rated Output Power
140.0 kph
(87.0 mph)
Max Speed
Wheel Arrangement
(Loco Facing Left)
Series Variants
Class 37 - Base Series Designation.
English Electric Type 3 - Alternative Designation.
Class 37/0 - Unmodified original series units (designated as such only when additional subclasses were added to the series line).
Class 37/3 - Rebuilt units.
Class 37/4 - Refurbished units; Brush alternators; Electric Train Supply (ETS) installed; modernized electricals.
Class 37/5 - Refurbished units; Brush alternators.
Class 37/6 - Class 37/5 units with ETS systems; RCH jumper cables.
Class 37/7 - Refurbished units; GEC G564AZ OR Brush series alternators; modernized electricals; increased operating weight.
Class 37/9 - Refurbished units; Brush alternators; Mirrlees MB275Tt OR Ruston RK270Tt engines fitted.
Operating Countries
United Kingdom

National flag of the United Kingdom
Customers / Operators:
British Railways; Colas Rail; Direct Rail Services; Europhoenix; EWS (English, Welsh and Scottish Railway / DB Cargo UK / DB Schenker); Locomotive Services Limited; Rail Operations Group; West Coast Railways
NOTE: Includes both past and present

Image of the BR Class 37 (English Electric Type 3)

Image of the BR Class 37 (English Electric Type 3)
Side profile illustration view of the BR Class 37 diesel-electric locomotive.
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