A locomotive which can operate with either electric or diesel power. The motors are electric but can be supplied from the diesel driven alternator or from the line's external power supply. The preference is usually for collecting electric power. The South African Class 38 is a locomotive of this type which has 3000v DC overhead electric supply as well as a 780 kW diesel engine. The UK Class 73 is another type but it collects electric power at 750v DC from a 3rd Rail to provide about 1500 h.p. or 600 h.p. with the diesel engine. The Swiss RHB Railway also had two electro-diesel locomotives.