British Rail Class 37

English Electric Type 3 British Rail Class 37
Class 37 in British Rail large logo livery at Muir of Ord railway station, 1988
Type and origin Power type Diesel-electric Builder English Electric at Vulcan Foundry and Robert Stephenson and Hawthorns Build date 1960–1965 Total produced 309
Specifications Configuration: ​  • Whyte Co-Co  • UIC Co'Co' Gauge 4 ft 8 1⁄2 in (1,435 mm) standard gauge Wheel diameter 3 ft 9 in (1.143 m) Minimum curve 4 chains (80 m) Wheelbase 50 ft 8 in (15.44 m) Length 61 ft 6 in (18.75 m) Width 8 ft 10+1⁄2 in (2.71 m) Height 12 ft 9 in (3.89 m) Loco weight 100 long tons (102 t) to 105 long tons (107 t) except 37/7 and 37/9 class - ballasted to 120 tonnes Fuel capacity 890 imp gal (4,000 L; 1,070 US gal) increased to 1,690 imp gal (7,700 L; 2,030 US gal) on rebuild Prime mover Built: English Electric 12CSVT 37/9: Mirrlees Blackstone MB275Tt or Ruston RK270Tt Generator Original: Main: English Electric EE822, Aux EE911/5C Rebuilt locos: Main: Brush BA1005A alternator, Aux: Brush BA606A Traction motors English Electric Transmission electrical (DC traction motors) MU working ★ Blue Star Train heating 37/0: Steam generator 37/4: Electric Train Heat Remainder: None Train brakes Vacuum, Dual, or Air
Performance figures Top speed 90 mph (140 km/h) Power output Engine: 1,750 bhp (1,305 kW) Tractive effort Maximum: 55,500 lbf (247 kN) Continuous: 35,000 lbf (156 kN) @13.6 mph (22 km/h) Brakeforce 50 long tons-force (498 kN)
Career Railroad(s) British Rail DB Schenker DRS West Coast Railway Company Number D6700–D6999, D6600–D6608; later 37001–37308 Nicknames Tractor, also Syphon, Growler or Slugs Axle load class Route availability 5 except subclass 37/7 RA 7

The British Rail Class 37 is a diesel-electric locomotive. It is also known as the English Electric Type 3. The Class was ordered as part of the British Rail modernisation plan.

The Class 37 became a familiar sight on many parts of the British Rail network. They were on Inter-City services in East Anglia and within Scotland. They also performed well on secondary and inter-regional services for many years. The Class 37 is known by railway enthusiasts as a "Tractor". This nickname came from the similarity of the sound of the locomotive.