• EMD Classification: JT42CWR - "Class 66"
• Built At: General Motors/EMD - London, Ontario (Canada)
• Wheel Arrangement: CO–CO
• Engine: General Motors 12N-710G3B-EC : 2.462 kW (3.300 HP) at 904 rpm
• Traction Alternator: General Motors AR8PHEH
• Auxiliary Alternator: General Motors CA6B
• Traction Motors: General Motors D43TR Axle Hung (6x)
• Power At Rail: 2.240 kW (3.000 HP) 
  Trucks: HTCR-E
• Wheel Diameter: 1,067 m.
• Sanding Equipment: 8 x 42,5 litre carbody mounted sand boxes with air delivery (50 kg per box)
• Gear Ratio: 81:20 (except for Freightliner 66/6: 83:18)
• Maximum Speed: 120 kmh (except for Freightliner 66/6: 74.7 kmh)
• Maximum Tractive Effort: 409 kN (except for Freightliner 66/6: 467 kN)
• Continuous Tractive Effort: 260 kN at 25.6 km/h (except for Freightliner 66/6: 296 kN at 22.5 kmh)
• Length: 21,35 m.
• Width: 2,64 m.
• Height: 3,91 m.
• Maximum Weight: 126.000 kg.
• Brake System: Westinghouse PBL3 Air Brake
• Brake Force: 68.000 kg.
• Fuel Capacity: 6.550 lit.
• Minimum Curve: 80 m. (radius)
• Multiple Working: JT26CW-SS (Class 59) , JT42CWR (Class 66) , JT42HW-HS (Class 67) 

The Class 66 locomotive (EMD classification JT42CWR) is a redesigned version of the Class 59 locomotive (EMD classification JT26CWSS). These Class 59 loco´s were already running in the U.K. since 1986.


The succes of the Class 66 also reached countries outside the UK. German operator HGK (Hafen und Güterverkehr Köln) ordered 2 loco´s which were delivered in 1999. Also in Scandinavia are already Class 66´s running for TGOJ Trafik (Sweden) and CargoNet (Norway).

Porterbrook Leasing started to lease a total of 20 loco´s to European operators like HGK, ShortLines, Rail4Chem, DLC Railway and ERS Railways. This was soon followed by orders from several other operators and leasing companies, which resulted in more than 60 loco´s in Europe nowadays. Also Poland got their first 66s in 2007.