Carrying wheels
Encyclopedia
The carrying wheels on a steam locomotive
are those wheels that are not driven, i.e. they are uncoupled and run freely, unlike coupled or driving wheels. They are also described as running wheels and their axle may be called a carrying axle. Carrying wheels are referred to as leading wheels if they are at the front, or trailing wheels if they are at the rear of the locomotive. See main article Bogie
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In particular reference to steam engines, the carrying wheels have a very important purpose of allowing the engine's weight distribution
to be altered. For example in the use of leading wheels it would allow the boiler to located further forward of the driving wheels, the weight of which counters the leverage imposed by the drawbar and the load of the pulled wagons/cars about the fulcrum of the rearmost driving wheel. Similarly the trailing wheels can move the fulcrum to the rearmost trailing wheel. Such change can dramatically improve the operating speeds of engines and their tractive effort
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Steam locomotive
A steam locomotive is a railway locomotive that produces its power through a steam engine. These locomotives are fueled by burning some combustible material, usually coal, wood or oil, to produce steam in a boiler, which drives the steam engine...
are those wheels that are not driven, i.e. they are uncoupled and run freely, unlike coupled or driving wheels. They are also described as running wheels and their axle may be called a carrying axle. Carrying wheels are referred to as leading wheels if they are at the front, or trailing wheels if they are at the rear of the locomotive. See main article Bogie
Bogie
A bogie is a wheeled wagon or trolley. In mechanics terms, a bogie is a chassis or framework carrying wheels, attached to a vehicle. It can be fixed in place, as on a cargo truck, mounted on a swivel, as on a railway carriage/car or locomotive, or sprung as in the suspension of a caterpillar...
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In particular reference to steam engines, the carrying wheels have a very important purpose of allowing the engine's weight distribution
Weight distribution
Weight distribution is the apportioning of weight within a vehicle, especially cars, airplanes, and trains.In a vehicle which relies on gravity in some way, weight distribution directly affects a variety of vehicle characteristics, including handling, acceleration, traction, and component life...
to be altered. For example in the use of leading wheels it would allow the boiler to located further forward of the driving wheels, the weight of which counters the leverage imposed by the drawbar and the load of the pulled wagons/cars about the fulcrum of the rearmost driving wheel. Similarly the trailing wheels can move the fulcrum to the rearmost trailing wheel. Such change can dramatically improve the operating speeds of engines and their tractive effort
Tractive effort
As used in mechanical engineering, the term tractive force is the pulling or pushing force exerted by a vehicle on another vehicle or object. The term tractive effort is synonymous with tractive force, and is often used in railway engineering to describe the pulling or pushing capability of a...
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