Diesel locomotive Therefore, diesel traction became economical for shunting before it became economical for hauling trains. The construction of diesel shunters began in 1920 in France, in 1925 in Denmark, in 1926 in the Netherlands, and in 1927 in Germany. After few years of testing, hundreds of units were produced within a decade. Diesel-powered or "oil-engined" railcars, generally diesel–mechanical, were developed by various European manufacturers in the 1930s, e.g. by William Beardmore and Company for the Canadian National Railways (the Beardmore Tornado engine was subsequently used in the R101 airship). Some of those series for regional traffic were begun with gasoline motors
Diesel locomotive deliver 1,200 volts (earlier traction "generators", DC to DC, had the capability to deliver only 600 volts). This improvement was accomplished largely through improvements in silicon diode technology. With the capability to deliver 1,200 volts to the traction motors, the necessity for "transition" was eliminated. A common option on diesel–electric locomotives is dynamic (rheostatic) braking. Dynamic braking takes advantage of the fact that the traction motor armatures are always rotating when the locomotive is in motion and that a motor can be made to act as a generator by separately exciting the field winding. When dynamic braking is utilized, the