The Static Proof: UIC 515-4 Chapter 5 Bogie Strength Tests

UIC Leaflet 515-4, titled “Passenger rolling stock – Trailer bogies – Running gear – Bogie frame structure strength tests,” is the standard for validating the structural safety of bogies used under passenger coaches. Chapter 5 specifically details the Static Test procedure (Programme of static tests). This phase verifies that the bogie frame can support exceptional loads—such as overcrowding or emergency braking—without suffering any permanent deformation or structural yielding.

The Role of Static Testing in Certification

Before a bogie is allowed to undergo fatigue testing (Chapter 6) or track trials, it must pass the static tests defined in Chapter 5. These tests are designed to simulate the maximum forces the vehicle might encounter once or twice in its lifetime. The primary acceptance criterion is simple but strict: after the load is removed, the bogie frame must return to its original dimensions (zero residual strain).

Key Static Load Cases

Chapter 5 mandates a series of load applications using hydraulic actuators on a test rig. The most critical cases include:

• Vertical Load ($F_{z}$): Applying a force equivalent to the fully loaded vehicle (mass + max passengers) multiplied by a safety factor (typically 2.0g or greater) to simulate a heavy vertical shock.
• Transverse Load ($F_{y}$): Simulating the centrifugal force and track shifting forces experienced in tight curves.
• Longitudinal Load ($F_{x}$): Simulating the forces from braking or shunting impacts (up to 3g or 5g depending on the component).
• Twist Load: Lifting one wheel to simulate running on twisted track (derailment safety check).

Comparison: Passenger (515-4) vs. Locomotive (615-4)

While the testing principles are similar, the magnitude of the loads differs significantly between passenger coaches and locomotives. The table below highlights the distinctions found in Chapter 5 of the respective standards:

Strain Gauge Instrumentation

Chapter 5 requires the extensive use of strain gauges placed at critical stress concentration points (welds, corners, suspension brackets). During the static test, stress levels are recorded to ensure they stay below the material’s Yield Strength ($R_{e}$). These measurements also serve as a calibration base for the subsequent fatigue tests described in Chapter 6.