UIC Leaflet 522-2: Technical Specifications for Automatic Wagon Couplers

What is UIC Leaflet 522-2?

UIC Leaflet 522-2 is the international technical standard titled “Technical conditions to be met by automatic couplers for wagons.” Unlike the standard screw coupling (governed by EN 15556), this leaflet focuses on systems that allow Rolling Stock to connect automatically upon impact.

Automatic couplers are essential for heavy-haul freight and modern rapid-transit systems. They eliminate the need for shunting staff to step between vehicles, significantly increasing safety during Shunting Operations and allowing for much higher Tensile Forces than traditional manual systems can handle.

Functional and Mechanical Requirements

The leaflet specifies the strict conditions required for an automatic coupler to be accepted for international traffic. These requirements ensure that a wagon from one manufacturer can seamlessly latch onto a wagon from another:

• Automatic Latching: The coupler must engage and lock securely when two wagons are pushed together at a specific speed range (typically 2 to 5 km/h).
• Simultaneous Connection: Beyond mechanical joining, the coupler must be capable of connecting the brake air pipes and, in some cases, electrical signal lines simultaneously.
• Gathering Range: The coupler head must have a specific “capture area” to account for vertical or lateral misalignment between wagons on curves or uneven track.
• Uncoupling Mechanism: Requirements for a manual or remote-controlled release lever that allows the coupler to remain in an “unlocked” state for shunting.

Structural Integration

Integrating an automatic coupler into a wagon requires specific modifications to the Underframe. UIC 522-2 dictates:

• Headstock Design: The headstock must be reinforced to handle the concentration of both buffing (compression) and draw (tension) forces through a single central point.
• Draft Gear: The coupler must be backed by a high-capacity energy absorption unit (draft gear) to protect the wagon structure from the high-impact forces of automatic coupling.

Safety and Reliability

Safety is the primary focus of the 522-2 testing regime. The coupler must demonstrate:

• Anti-Creep Protection: A mechanical lock that prevents the coupler from opening due to vibration or track shocks during transit.
• Visual Indication: A clear, external signal (usually a colored lever or pin) that shows shunting staff whether the coupler is fully locked or merely touching.

Comparison: Manual Screw Coupling vs. UIC 522-2 Automatic Coupler