Prior to 1926 the starting of railway-type Diesel engines was generally accomplished by the use of compressed air. This method of starting had certain disadvantages in locomotive operation, and in an effort to overcome them, a trial installation was made of an electric starting system. This involved the application of a 56-cell lead-acid type storage battery and the addition of a special series winding in the main generator of the locomotive, through which the battery current was passed when starting causing the generator to function as a series-wound motor. Since that time this method has been used successfully on practically all Diesel-electric locomotives.