The generator also offered electric starting of the petrol engine by connecting to another locomotive, and the locomotives could also be used as mobile generators. In a parallel order 100 similarly rated locomotives were made by British Westinghouse, who were probably the original designers, though the DC generator/DC motor speed control mechanism is an early example of the application of a Ward Leonard control system (Harry Ward Leonard patented its application to vehicles in 1903). The selection of this drive system was in part because the War Department had originally considered using overhead electric as an alternative way of powering the locomotives, but it was subsequently decided this was not practical.