Class 57 (Brush Traction/EMD 2,500/2,750hp Type 4 Diesel-Electric)

The Class 57 was devised as a low-cost way to create a "new" diesel locomotive [1]. Class 47s were gutted down to their body shells and then refitted with refurbished and reconditioned equipment including second-hand General Motors diesel engines and reconditioned Class 56 alternators [2]. The resulting locomotives still look like Class 47s (though some have had major modifications to the cab ends) but are completely different inside.

Number built: 33 rebuilds
Built: 1964-67 (as Class 47)
Rebuilds 1998-2005
Builder: Brush Traction (rebuilds)
BR Crewe
Engine: EMD 645-12E3 diesel (57/0)
EMD 645-12F3B diesel (57/3 and 57/6)
Power: 2, 500 hp (1, 864 kW) (57/0)
2, 750 hp (2, 051 kW) (57/3 and 57/6)
Wheel arrangement: Co-Co

The initial batch of twelve (57/0) were built as freight locomotives for Freightliner and now are operated by DRS. Later on Virgin Trains had 16 rebuilt (57/3) to haul VT and Cross Country multiple units like the Class 390 on "Thunderbird" duties (for diversionary routes and to rescue units in the event of an overhead line failure), these have provision for electric train heating and drop-head Dellner couplers to enable working with Virgin's multiple units. DRS now operate these "Thunderbird" locomotives.

Finally First Great Western (GWR) have had 4 rebuilt also with ETH (57/6) to work sleeper trains from Paddington to Penzance. Some Class 57s are now in service with West Coast. They have also served with Arriva Trains Wales, Network Rail and Colas Rail.
West Coast 57 313 at Derby 
DRS 57 306 on Thunderbird duties at Rugby

West Coast 57 316 at Derby

DRS 57 306 at Kidderminster SVR

DRS Thunderbird 57 307 at Crewe

[1] Colin J. Marsden, Traction Recognition (2nd Edition) (Ian Allan, 2009) p. 52
[2] Pip Dunn, British Rail Main Line Locomotives Specification Guide (Crowood Press, 2013) p. 126