Steam locomotives all need water to make the steam that makes the wheels turn. But they don’t all get it in the same way. One kind never has to stop and wait for its tender to be filled. Instead it has a scoop that dips down as the engine passes over a long track-pan of water set between the rails. With no time lost, the scoop sucks up water into the tank. The men say, “She’s jerked a drink.” In winter, the track-pans are heated to keep the water from freezing. Two kinds of locomotive don’t even need water. Electric engines use electric current instead of steam to turn the wheels. They get the current from wires along the tracks. Diesel-electrics are more complicated. They have oil-burning engines that make electric current right in the locomotive, and this current runs motors that turn the wheels. There are several engines inside a Diesel-electric locomotive. If one of them gets out of order during the trip, the others keep on delivering power while the one is repaired. The engineer and the fireman sit in the cab at the very front of a Diesel-electric. They can watch the track through front windows. [Illustration] The cab is at the front of the engine shown on this page, too, but it is a steam locomotive. It burns oil instead of coal, so the cab doesn’t have to be right next to the tender. The men call it the Big Wamp. It hauls tremendously long freight trains across the Rocky Mountains. One siding where the men stop to eat is so long that there has to be a restaurant at each end! [Illustration: SANTA FE 6000 DIESEL NEW HAVEN EP-4] Many railroads are buying more and more Diesels as their steam locomotives wear out. The Santa Fe Railroad’s Diesel at the top of the page is called a 6000 because it has six thousand horsepower. The New York, New Haven & Hartford uses electric locomotives because it can get power for them easily. The one above is called the EP-4 because it is the fourth model of electric passenger engine the road has used. [Illustration: PERE MARQUETTE BERKSHIRE NEW YORk CENTRAL HUDSON] All the others in these pictures are steam locomotives, but the T-1 is a special kind. Its name means that it is the first of a type called a turbine locomotive. An ordinary engine lets out its used-up steam in puffs, as if it were panting. A turbine doesn’t, and so it never makes the familiar chuff-chuff noise. [Illustration: ERIE PACIFIC CANADIAN PACIFIC MIKADO] The name on each of the other steam locomotives shows that it belongs to a type that has a particular arrangement of wheels. All Pacific-type engines have four small wheels in front, then six big ones, then two small ones in back. Mikados have two small, eight big, then two small ones. The way to write these wheel arrangements is 4-6-2 and 2-8-2. If an engine is called a 2-6-0, that means it doesn’t have any small wheels at the back. A 2-8-8-2 has two sets of big wheels and two sets of small ones. And 0-8-8-0 means there are no small wheels at all.