Steel tracks can be straight or curved to steer the train since steel is easily bent into shape. Finally, electrical trains will have either a third power rail or overhanging wires that supply the electricity. They may also be surrounded by fences to prevent animals and people from wandering on to the tracks. In many cases, railroad tracks are elevated above the surrounding ground and have drainage systems to remove water. The foundation may be made of sand or concrete. Segments of rail track may connect to one another by bolted plates called fishplates, but most modern rail segments are welded together to provide a smooth ride.īeneath the rails, the track is sometimes cushioned or ballasted. The weights of the rails vary from 80 to 160 pounds (36 to 73 kilograms) per yard depending upon the type of train operating on the tracks and the country. The rail has a wide base or foot, a narrow web and a head (wider than the web, but not as wide as the foot). When rail workers are laying train tracks, they often use a flat-bottom steel rail that resembles the steel I-beam girders of construction. What's on top of the undercarriage depends upon the type of railroad car, and there are several. On each end of the undercarriage, couplers, which are like hooks, connect the cars. A mechanical hand brake is also used in case the air brakes fail (usually when there's insufficient air pressure to drive them).Īll railroad cars have an undercarriage that contains wheels and a suspension system to buffer the ride. The operator also throttles the engine back to slow the train, like when you take your foot off the gas pedal when stopping your car. The friction between the brake pad and the wheels slows the wheels' motions. Air brakes use high-pressure air to drive the brake foot against the wheel. Regardless of the type, locomotives use air brakes and hand brakes to stop the engine. The brake allows the locomotive to slow and stop. The reversing gear enables the locomotive to back up. The throttle controls the speed of the locomotive. Operators control the train by using the throttle, reversing gear and brake. Electrical locomotives are used on subways and many commuter rail systems. Transformers transfer the voltage from the lines, and the electrical current drives the motors (AC or DC) on the wheels. They get the electricity from a third rail, or electrical line, along the track.
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Many trains intersperse multiple locomotives throughout their lineup to increase and distribute the power.īesides steam- and diesel-powered locomotives, many trains operate solely on electrical power. In fact, diesel locomotives have their very own article - How Diesel Locomotives Work. The steam locomotive lasted for about a century, but was eventually replaced by the diesel locomotive, a mighty mechanical wonder that may consist of a giant engine along with electric alternators or generators to provide electrical power to the train.
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The first locomotives did this with a steam engine, which you can read more about in How Steam Technology Works. The job of the locomotive is to change the chemical energy from the fuel (wood, coal, diesel fuel) into the kinetic energy of motion. Mouse over the part labels to see where each is located on the diesel engine.
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Stick around as we talk about train technology, how trains move people and freight, and what the future of rail transportation may hold. In the ongoing energy crisis, however, trains, which run on diesel and sometimes even biodiesel fuel, may regain their former popularity with passengers as we move through the 21st century. A developed interstate highway system and extensive federal regulations took their toll on trains. Diesel locomotives had replaced steam ones.īut by the mid-20th century, the decline of the U.S. railroads operated 254,000 miles (408,773 kilometers) of track. Towns sprouted along the railway lines, and the railroad hastened westward expansion. railroad network expanded again, and the country's first transcontinental railway was completed in 1869. Railroads served as the main mode of transportation and made it cheap and easy to ship supplies and goods, even for Union and Confederate armies during the Civil War.Īfter the Civil War, the U.S. rail workers had laid more than 30,000 miles (48,280 kilometers) of track, more than in the entire world.
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Horses just couldn't top that.Īcross the ocean, the B&O Railroad Company established itself as the first U.S. Steam-powered locomotives carried six coal cars and up to 450 passengers a distance of 9 miles (14 kilometers) in less than an hour. The Stockton & Darlington Railroad Company in England became the first public railroad to carry passengers and freight. But it wasn't until the steam locomotive was invented in 1797 in England that the railroad as we know it began to take shape.