Why is the steel rail in the shape of "I"?

The steel rail is an important component of the railway track. The main function of the steel rail is to guide the train wheels to move forward, smoothly bear the huge pressure of the wheels and transmit it to the sleepers. At the same time, the steel rail must provide a continuous, smooth and least resistance rolling surface for the wheels.

Do you know why the steel rail is in the shape of "I";? In order to ensure the safe operation of trains with kilotons and 10,000 tons, steel rails need to meet three characteristics: they can withstand the pressure exerted by heavy-duty trains, meet the stability of trains at high speeds, match the wheel flanges, and are the best to resist flexural deformation.

The force that the train acts on the steel rails is mainly the vertical force. An empty freight train has a self-weight of at least 20 tons, and a fully loaded train can weigh 10,000 tons. Such a large weight and pressure can easily cause the rail steel to be flexed and deformed (physical deformation)

The "I";-shaped steel rail is the best section to resist flexural deformation, ensuring smooth train operation. The steel rail is a wide-bottomed "I";-shaped section composed of three parts: rail head, rail waist and rail bottom. The train is mainly in contact with the rail head during operation. In order to ensure the smooth running of the train, the wheel-rail contact must be in close agreement and wear-resistant performance. On the one hand, the narrow and thick rail head can be perfectly embedded in the wheel rim, and on the other hand, it is enough for the wheel and rail to wear.

The steel rail bottom is relatively wide and the force-bearing area is large. Coupled with the combined action of fasteners and sleepers, the train can run smoothly.

After a century of development of steel rails, the "I";-shaped structure has been in use today and has become a classic design that spans the age.

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