The Eurotunnel Class 0001 Bo-Bo diesel-electric locomotives were built by Maschinenbau Kiel (manufacturers designation DE 1004) between 1991 and 1992.

When operating in the United Kingdom, the locomotives are assigned a TOPS classification as Class 21.

They are cleared to travel to Calais, Ashford, or St. Pancras; since 2007 they have been authorised to rescue trains on High Speed 1 in the event of a power failure.

[6] They have also been used to haul the SNCF TGV Iris 320 test train through the Channel Tunnel.

[9] Following a series of tunnel breakdowns due to snow during winter 2009/10, during which the locomotives were extensively used,[10] in November 2010 Eurotunnel announced it was to acquire two more Krupp rescue locomotives[note 1] with co-financing from Eurostar, at a cost of €1.3 million.