The Outer Rim: UIC Leaflet 810-2 Wheel Tyre Specifications

Introduction to UIC Leaflet 810-2

While modern high-speed trains predominantly use “monobloc” (solid) wheels, many locomotives, heritage fleets, and freight wagons still utilize “tyred wheels.” A tyred wheel consists of a wheel center and a separate steel ring—the tyre—shrunk onto it. UIC Leaflet 810-2, titled “Technical specification for the supply of rough rolled wheel tyres for tractive and trailing stock,” governs the quality of this critical outer ring.

The integrity of the tyre is a matter of life and death; a fracture or a loose tyre can lead to catastrophic derailments (as historically evidenced). Therefore, UIC 810-2 imposes strict metallurgical and mechanical controls on the manufacturing process.

Snippet Definition: What is UIC 810-2?

UIC Leaflet 810-2 is a technical specification for the supply of rough rolled steel tyres used on railway vehicles. It defines the chemical composition of the steel, the manufacturing method (rolling), heat treatment requirements, and the mandatory destructive and non-destructive tests to ensure the tyre can withstand thermal and mechanical loads without cracking.

Manufacturing and Steel Grades

The standard requires that tyres be manufactured from steel produced via an electric furnace or basic oxygen process, followed by vacuum degassing to remove hydrogen (preventing flaking).

• Forging & Rolling: The steel ingot is punched and rolled into a ring shape. The “rough rolled” state means it has the general shape but requires final machining by the wheelset assembler.
• Heat Treatment: Tyres undergo normalizing or quenching and tempering to achieve the required hardness. This is crucial because the tyre acts as the wear surface against the rail and the brake blocks.

Testing and Acceptance

UIC 810-2 mandates a rigorous inspection regime before the tyres are shipped to the wheel shop:

1. Mechanical Tests

• Tensile Test: Verifies the ultimate strength and yield point of the steel.
• Impact Test (U-Notch or V-Notch): Measures the material’s toughness. Tyres must not be brittle, as they experience high shock loads at rail joints.

2. Ultrasonic Testing

Every tyre must be sonically scanned to ensure there are no internal voids or inclusions. UIC 810-2 defines different classes of internal purity depending on the intended speed and load of the vehicle.

Comparison: Tyred Wheels (UIC 810-2) vs. Monobloc Wheels (UIC 812-3)

Understanding the difference between the component (tyre) and the solid wheel is essential for maintenance strategies.

Operational Context

The tyre is held in place by an interference fit (it is heated to expand, placed on the wheel center, and cools to grip tight) and often a retaining ring (Gibson ring). UIC 810-2 ensures the steel has the correct thermal properties to handle this shrink-fitting process without developing stress cracks.