British Rail Class D20/2

class of 5 (A1A)(A1A) 2000hp diesel-hydraulic locomotives

The British Railways Class D20/2 diesel-hydraulic locomotives were built by the North British Locomotive Company in Glasgow during 1957 and 1958. Although never assigned a TOPS class as they were withdrawn before TOPS was introduced, British locomotive enthusiasts coined the term "Class 41". All were named after Royal Navy vessels, hence the nameplates each bore a subtitle "Warship Class".

British Rail Class D20/2
'Warship' Diesel-hydraulic at Reading (General) on an Up express.
Type and origin
Power typeDiesel-hydraulic
BuilderNorth British Locomotive Company
Serial number27660–27664
Build date1958–1959
Total produced5
 • WhyteA1A-A1A
 • UIC(A1A)'(A1A)'
Gauge4 ft 8 12 in (1,435 mm) standard gauge
Wheel diameterDriving: 3 ft 7 in (1.092 m)
Idling: 3 ft 3+12 in (1.003 m)
Wheelbase50 ft 0 in (15.24 m)
Length65 ft 0 in (19.81 m)
Width8 ft 8 in (2.64 m)
Height12 ft 10 in (3.91 m)
Loco weight117 long tons (119 t)
Fuel capacity800 imp gal (3,600 L; 960 US gal)
Prime moverNBL-MAN L12V 18/21S, 2 off
TransmissionHydraulic, Voith L306r
MU working Orange Square
Train heatingSteam
Train brakesVacuum
Performance figures
Top speed90 mph (145 km/h)
Power outputEngines: 1,000 bhp (746 kW) × 2
Tractive effortMaximum: 50,000 lbf (222 kN)
Continuous: 39,600 lbf (176 kN)
Brakeforce88 long tons-force (877 kN)
Railroad(s)British Railways
Axle load classRoute availability
RetiredDecember 1967
DispositionAll scrapped