UIC Leaflet 510-4: Maintenance and Testing of Wheelsets in Service

What is UIC Leaflet 510-4?

UIC Leaflet 510-4 is the international standard titled “Wagons – Wheelsets – Technical conditions for the maintenance and use of wheelsets in service.” Because wheelsets are Safety-Critical Components, their failure can lead to catastrophic derailments. This leaflet provides the mandatory maintenance intervals and inspection criteria to identify defects before they lead to failure.

The standard focuses on the Axle Integrity and wheel condition while the vehicle is operational (in-service), rather than just the manufacturing phase. It ensures that regardless of which country a wagon is in, its wheelsets are inspected to a consistent and high safety standard.

Inspection and Testing Methodologies

A central pillar of UIC 510-4 is the application of Non-Destructive Testing (NDT). Since fatigue cracks often start beneath the surface or in hard-to-see areas, the leaflet mandates specific techniques:

• Ultrasonic Testing (UT): Used primarily for the hollow-bore or end-face scanning of axles to detect internal transverse cracks.
• Magnetic Particle Inspection (MPI): Applied to the axle body and wheel seats during overhauls to find surface-breaking fatigue cracks.
• Visual Inspection: Standardized criteria for identifying “flats,” “shelling,” or “spalling” on the wheel tread caused by heavy braking or poor adhesion.
• Dimensional Measurement: Checking for wheel wear (flange thickness and height) to ensure the wheel remains within the safe Rolling Stock geometric limits.

Maintenance Intervals and Limits

UIC 510-4 defines the “limit of wear” for various wheelset types. It categorizes maintenance into:

• Operational Checks: Frequent visual inspections conducted in sidings or during train formation.
• Periodic Maintenance: More intensive inspections based on mileage (kilometers) or time elapsed.
• Overhaul (Revision): Full disassembly of the wheelset, including bearing replacement and comprehensive NDT of the axle.

Evolution and EN 15313

In the modern European regulatory framework, the technical content of UIC 510-4 has been largely integrated into EN 15313 (Railway applications – Wheelsets and bogies – In-service wheelset operation and maintenance). However, UIC 510-4 remains the primary reference for many international railway unions and provides the historical basis for current Rolling Stock Maintenance safety cases.

Comparison: Wheelset Defect Severity Levels