To: Patricia Trinchero who wrote (2591 ) 3/15/2008 3:50:12 PM From: coug Read Replies (2) | Respond to No.. Diesel electric locomotives.. A couple of links..The Diesel Electric Locomotive is the dominant type of locomotive in the world today. But what does the term "Diesel-Electric" really mean? There have been five major types of locomotives used in the history of railroads; The Steam Locomotive, The Electric Locomotive, The Diesel (or gas) Torque-Converter Locomotive, The Turbine Electric Locomotive, and finally, the Diesel Electric. A steam locomotive burns coal or oil, converting water into steam, and then uses the steam to drive pistons, which are connected by drive rods to the wheels. A straight electric locomotive, on the other hand, uses electricity provided by an overhead wire or "3rd rail" next to the tracks, to power electric motors (known as "traction motors") that are geared directly to its wheels. Straight electric locomotives are usually very powerful, fast, and long-lived machines (The Pennsylvania RR's famous GG1 is a classic example of a straight electric). Our third type, the diesel or gas torque-converter locomotive uses some kind of internal combustion engine which is geared directly to the drive wheels using a "torque converter", more commonly known as a "clutch". The disadvantages of this arrangement are many, as burning out a clutch 200 miles from your maintenance base would present obvious problems. The fourth type listed, the turbine-electric, is also one of the rarest types. The basic idea was to burn some kind of fuel to produce either steam or hot combustion gases, which were then passed through a turbine, which would spin at high speed. The turbine would drive an electric generator, which would provide electricity to traction motors on the wheels of the locomotive. Some turbines burned coal, others burned oil, and most were experimental in nature. The Union Pacific Railroad had a whole series of turbine-electrics that burned bunker C fuel. The last of their series were the most powerful locomotives ever built, at 10,000 h.p. each. Although successful, they had high maintenance costs, and used almost as much fuel at idle as they did at full throttle. the diesel-electric uses a diesel engine to drive an electric generator, which then supplies the current to traction motors, which are geared directly to the locomotive's wheels. One of the main advantages of this arrangement is that, since the engine is not directly attached to the wheels, starting a heavy train cannot "stall" the engine, as in the case of the torque-converter locomotive. The motors simply heat up until they start the train moving, at which point the current level drops. Another advantage is that, unlike the straight electric locomotive, expensive and hard to maintain overhead wires (called "catenary") or third rails are not necessary. This is less of a factor in Europe, where distances are smaller, but since some North American railroads have tens of thousands of miles of track, it's a major consideration. And compared to a steam locomotive, Diesels require very little maintenance, and can be started up and shut down instantly. Steam locomotives would take hours to build up a head of steam, and required frequent boiler rebuilds and costly maintenance by skilled shop forces. essortment.com Rail Freight Usually Most Energy-Efficient lafn.org
