Rails
Rails give the railway its name, they provide the surface on which train wheels traverse but there is more to them than meets the eye.
Characteristics of Railway Rails
Railway rails are integral components of the railway infrastructure, playing a crucial role in ensuring safe and efficient train operations. Understanding the key characteristics of rails is essential for appreciating their importance in the rail system's functionality. Let's delve into the fundamental characteristics that define railway rails
1. Hard, Unyielding Surface to Carry Wheels
Railway rails must provide a hard and unyielding surface to support the weight of train wheels effectively. This characteristic ensures that the rails do not deform or succumb to wear under the immense pressure exerted by passing trains. Since the inception of railway tracks, this primary function of rails remains unchanged.
2. Acting as a Beam to Transmit Loads
Railway rails must provide a hard and unyielding surface to support the weight of train wheels effectively. This characteristic ensures that the rails do not deform or succumb to wear under the immense pressure exerted by passing trains. Since the inception of railway tracks, this primary function of rails remains unchanged.
3. Assisting in Steering the Trains
Railway rails collaborate with wheel surfaces to facilitate the steering of trains, particularly around curves. The design of the gauge corner of the rail complements the wheel tread and flange, aiding in maintaining the train's trajectory through curves. This geometric compatibility, combined with track cant, contributes to safe and efficient train navigation.
4. Performing Secondary Functions
In addition to their primary roles, railway rails serve various secondary functions critical to other railway disciplines. These include facilitating electrical conductivity for track circuit train detection systems and serving as returns for overhead line equipment (OLE) and other traction systems. Rails' versatility extends beyond their primary load-bearing function, integrating seamlessly into diverse railway subsystems.
Parts of a Rail
Railway rails consist of several distinct parts and surfaces, each fulfilling specific functions essential for their structural integrity and operational efficiency
1. Rail Head
The rail head forms the top section of the rail, providing the surface on which train wheels run. Its shape is meticulously designed to accommodate the wheel profile, ensuring optimal ride quality and minimizing contact stresses. Additionally, the rail head's design aids in the proper distribution of forces, particularly during curved track traversal, contributing to overall track stability.
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Crown: The top surface of the rail when the track is straight and flat, serving as the primary contact point for train wheels.
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Gauge Corner: The radiused corner of the rail head located on the inside of the track, adjacent to the wheel flange. Proper maintenance of the gauge corner is crucial to prevent wear and maintain track integrity.
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Gauge Face: The flat, straight edge of the rail head, used as a reference point for measuring track gauge.
2. Rail Web
Situated below the rail head, the rail web serves as the connecting link between the head and the foot of the rail. It contains essential markings, such as rail grade and manufacturing details, and accommodates holes for joint or bond installations.
3. Rail Foot
The rail foot constitutes the bottom section of the rail, providing critical support and stability to the entire rail structure. It consists of several key elements:
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Lower Fishing Surface: The top surface of the foot where fishplates make contact with the rail, facilitating rail joint connections.
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Toe Area: A designated surface for clip attachment, securing the rail to the sleeper and housing to prevent lateral movement.
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Base: The large flat surface at the bottom of the rail foot, responsible for evenly distributing loads onto the baseplate and preventing rail rotation induced by lateral forces.
Rail Types, Profiles, and Grades
Railways encompass a diverse array of rail types, profiles, and grades tailored to specific operational requirements and environmental conditions.
Rail Types
Rail types categorize rails based on their design and intended function within the railway system. Common types include flat bottom rails, bullhead rails, grooved rails, switch rails, guard rails, and conductor rails. Each type serves distinct purposes, ranging from supporting standard train operations to facilitating specialized functions like tram or metro systems and electrical power distribution.
Rail Profiles
Rail profiles denote variations in rail dimensions and shapes, often designated by their weight per unit length and regional standards. Profiles, such as CEN56 or UIC, feature specific geometries optimized for different operational requirements and regional preferences. These profiles undergo continual refinement to enhance performance, durability, and compatibility with associated railway components.
Rail Grades
Rail grades refer to the hardness of the rail material, measured on the Brinell scale, to withstand wear and deformation from train wheel interactions. Common rail grades, such as 260, indicate the material's resistance to deformation, with higher grades offering superior durability and reduced maintenance requirements. Methods like alloying and heat treatment enhance rail hardness, optimizing performance in demanding operational conditions.