Power and Guidance: UIC Leaflet 896-2 Rail Specs

Introduction to UIC Leaflet 896-2

Not all rails are designed to carry the vertical weight of a train. Some are designed to push the wheels sideways to prevent derailment, while others are designed to carry massive electrical currents to power the motors. UIC Leaflet 896-2, titled “Track – Technical specification for the supply of check rails and conductor rails,” governs these specialized profiles.

In a complex switch (turnout), the “Check Rail” is the silent guardian that ensures the train goes left or right without the wheel flange hitting the crossing nose. Meanwhile, in metro systems, the “Conductor Rail” (Third Rail) acts as the power line. UIC 896-2 provides the recipe for manufacturing these critical, non-load-bearing (in the vertical sense) steel components.

Snippet Definition: What is UIC 896-2?

UIC Leaflet 896-2 is a technical specification for the supply of two specific types of railway rails: Check Rails (used in switches and sharp curves to guide wheel flanges) and Conductor Rails (used for third-rail electrification). It defines the chemical composition, mechanical properties, electrical conductivity (for conductor rails), and geometric tolerances required for acceptance.

The Two Roles: Guidance vs. Power

This leaflet covers two distinct components that share a similar manufacturing process (hot rolling) but serve different purposes.

1. Check Rails (Guard Rails)

Located inside the running rail, typically in turnouts or sharp curves.

• Function: It engages the back of the wheel flange to constrain the axle’s lateral movement. In a switch, it prevents the opposite wheel from striking the “frog” (crossing nose).
• Profile: Often asymmetric (e.g., 33C1 profile). Unlike the I-beam shape of a running rail, check rails are often blocky or U-shaped to withstand high lateral impact forces.
• Material: Requires high wear resistance but sufficient ductility to avoid snapping under impact.

2. Conductor Rails (Third Rail)

Located alongside the track, mounted on insulators.

• Function: To transmit DC electricity (e.g., 750V) to the train via a sliding shoe.
• Requirement: The priority here is Low Electrical Resistance. The steel chemistry is altered (often lower carbon, ultra-low manganese) to maximize conductivity, even if it makes the steel softer (since it doesn’t carry the train’s weight).

Material and Testing Requirements

UIC 896-2 mandates different tests for the two types:

• Mechanical Tests (Check Rails): Tensile strength and elongation tests are critical. A check rail must absorb the violent side-kick of a locomotive entering a switch without cracking.
• Electrical Tests (Conductor Rails): Specific resistivity measurements (micro-ohm per meter). The manufacturer must prove the rail conducts electricity efficiently to prevent voltage drops over long distances.
• Dimensional Tolerances: The “fishing surface” (where the rail connects to chairs or supports) must be precise to ensure correct alignment relative to the running rail.

Comparison: Check Rails vs. Running Rails (UIC 860)

Why do we need a separate leaflet from the standard rail spec?

Transition to EN Standards

In modern European procurement, UIC 896-2 has largely been superseded by the **EN 13674** series:

• Check Rails: Now covered under EN 13674-3 (Check rails).
• Conductor Rails: Often covered by specific utility standards or broader conductive steel specs, as third-rail technology varies widely (steel vs. aluminum-steel composite).