Foundation of Stability: Rolled Profiles for Baseplates (UIC 864-7)

What is UIC Leaflet 864-7?

UIC Leaflet 864-7, titled “Rolled profiles for baseplates for 54 kg/m and 60 kg/m rails,” is a technical specification issued by the International Union of Railways (UIC). It defines the geometric, chemical, and physical characteristics of the long steel bars (profiles) that are manufactured specifically to be cut and machined into Baseplates (also known as tie plates).

In the Track Superstructure, the baseplate serves as the critical interface between the steel rail and the wooden or concrete sleeper. UIC 864-7 ensures that the raw rolled steel used for these components meets rigorous standards to support the heavy axle loads associated with UIC 54 Rail and UIC 60 Rail profiles without deforming or cracking.

Function and Manufacturing

The profiles described in this leaflet are produced via hot rolling. The resulting baseplates perform several vital functions in the Rail Fastening System:

• Load Distribution: They spread the concentrated vertical load of the train wheels over a larger area of the sleeper, preventing mechanical wear or crushing of the sleeper.
• Rail Inclination: The rolled profile typically features a cant (slope), usually 1:20 or 1:40, to ensure the wheel-rail contact is optimized for steering and stability.
• Gauge Retention: The “shoulders” of the profile help hold the rail securely in place, maintaining the correct track gauge.

Comparison: Profile Types and Characteristics

The leaflet distinguishes between profiles based on the rail type they are intended to support. The table below outlines the general differences in application and design.

Quality Control and Tolerances

UIC 864-7 is not just about dimensions; it is a quality assurance document. It mandates:

• Surface Finish: The rolled bars must be free from cracks, laps, or scales that could initiate structural failure.
• Dimensional Tolerances: Strict limits on the thickness of the plate and the height of the shoulders are enforced to ensure the rail fits perfectly.
• Straightness: The bars must be straight to allow for automated cutting and hole-punching during the baseplate manufacturing process.