What is the purpose of the EN 15624 standard?

The EN 15624 standard specifies the technical requirements for the design, performance, and testing of empty-loaded changeover devices used in the braking systems of railway wagons. Its purpose is to ensure these critical components function safely and reliably, providing the correct braking force for a wagon's specific load.

What is an empty-loaded changeover device on a railway wagon?

An empty-loaded changeover device is a pneumatic or mechanical-pneumatic switch in a wagon's braking system. It adjusts the brake cylinder pressure to one of two levels: a lower force for when the wagon is empty and a higher force for when it is loaded. This prevents wheel skidding on empty wagons and ensures adequate stopping power for loaded wagons.

Why is adjusting brake force based on wagon load important?

Adjusting brake force is critical for safety and efficiency. Applying a 'loaded' brake force to an empty wagon can cause the wheels to lock and slide, leading to wheel damage and potential derailment. Applying an 'empty' force to a loaded wagon results in dangerously long stopping distances, compromising the safety of the entire train.

What are the main types of empty-loaded changeover devices?

There are two main types. Manual devices require a person to physically move a lever to select the 'empty' or 'loaded' setting. Automatic devices sense the wagon's load, typically by measuring the deflection of its suspension, and switch between braking levels automatically without human intervention.

How does EN 15624 contribute to railway safety?

EN 15624 enhances railway safety by ensuring predictable and appropriate braking performance for freight wagons under all load conditions. By standardizing these devices, it helps prevent wheel lock-ups and skidding, which can cause derailments, and ensures that trains can stop within safe, calculated distances, contributing to overall operational stability and interoperability.

Why EN 15624 Boosts EU Rail Braking Safety

Master EN 15624: the standard for empty-loaded changeover devices. These critical components ensure precise, safe braking for railway wagons, adapting force to every load.

December 15, 2024 2:02 am

Understanding EN 15624: Empty-Loaded Changeover Devices for Railway Braking

The EN 15624 standard specifies the requirements for the design, performance, and testing of empty-loaded changeover devices used in the braking systems of railway vehicles. These devices are a critical safety component, ensuring that the braking force applied to a wagon is appropriate for its current weight, whether it is empty or fully loaded.

The Core Function of Empty-Loaded Changeover Devices

The fundamental principle behind the need for an empty-loaded device is physics. The braking force required to stop a moving object is directly related to its mass. A fully loaded freight wagon can be several times heavier than an empty one. If the same high braking force required for a loaded wagon were applied to an empty one, the wheels would likely lock up, causing them to slide along the rail. This condition, known as skidding, can lead to significant wheel damage (wheel flats) and increase the risk of derailment. Conversely, if the low braking force intended for an empty wagon were applied to a loaded one, the stopping distance would be dangerously long, compromising the safety of the entire train.

An empty-loaded changeover device solves this problem by providing two distinct braking levels. It acts as a switch in the pneumatic braking system, adjusting the brake cylinder pressure to a pre-set ’empty’ or ‘loaded’ level based on the wagon’s weight.

Key Technical Requirements of EN 15624

EN 15624 outlines a comprehensive set of technical specifications to ensure these devices are reliable, safe, and interoperable across European rail networks. These can be broken down into several key areas.

Functional Specifications

Braking Regimes: The device must provide at least two distinct and stable braking force settings: one for the ’empty’ state and one for the ‘loaded’ state.
Changeover Point: The standard defines the need for a specific ‘changeover load’. This is the total wagon mass at which the device must switch from the ’empty’ to the ‘loaded’ setting. The exact value is determined by the wagon’s design and operational parameters.
Pneumatic Performance: The device must not introduce significant delays into the brake application or release times. It must be able to operate reliably within the pressure ranges specified for railway pneumatic brake systems.
Fail-Safe Principle: In the event of a failure of the sensing mechanism (especially in automatic devices), the device should ideally default to a safe state, which is typically the ‘loaded’ position to ensure sufficient braking force is always available.

Design and Construction Principles

Durability and Environment: Components must be designed to withstand the harsh operating environment of a railway vehicle. This includes resistance to shock, vibration, extreme temperatures (-40°C to +70°C), humidity, and contamination from dust, water, and oil.
Materials: Materials used must be resistant to corrosion and suitable for long-term use without significant degradation of performance.
Indication: For manual devices, a clear and unambiguous visual indicator must show the current setting (‘Empty’ or ‘Loaded’). This indicator must be easily visible to railway staff during inspections.

Types of Changeover Devices

The standard covers the two primary types of empty-loaded changeover devices used in the industry:

Manual Devices: These are the simpler type, featuring a large handle or lever that must be physically moved by a yard operator. The position of the handle (e.g., horizontal for empty, vertical for loaded) determines which braking regime is active. While mechanically simple, their effectiveness depends entirely on correct human operation.
Automatic Devices: These devices automatically sense the load of the wagon and switch accordingly. The most common method involves a mechanical linkage to the wagon’s suspension system. As the wagon is loaded, its body lowers relative to the bogie; this deflection is measured by the device, and once it passes the changeover threshold, it automatically switches the pneumatic setting to ‘loaded’.

Testing and Approval Procedures

To comply with EN 15624, a device must undergo rigorous testing. This includes laboratory tests for function, endurance, performance under climatic stress, and vibration resistance. Following successful lab tests, field trials on a representative wagon are required to validate its performance in a real-world operational environment.

Comparison of Manual vs. Automatic Devices

The choice between a manual and an automatic device depends on the type of wagon, its intended use, and operational considerations.

Feature	Manual Changeover Device	Automatic Changeover Device
Operating Principle	Lever operated by personnel.	Senses wagon load via suspension deflection.
Reliability	Dependent on human action; high risk of error (e.g., forgetting to switch).	High; removes human error from the switching process.
Human Intervention	Required every time the wagon’s load state changes.	None required for the changeover function during operation.
Initial Cost	Lower.	Higher due to increased mechanical complexity.
Maintenance Complexity	Simpler; primarily involves checking the lever and indicator.	More complex; requires calibration and inspection of sensing linkage.
Typical Application	Older wagon fleets or wagons in dedicated service where load state rarely changes.	Modern freight wagons, especially those in mixed-traffic and international service.

Role in Railway Interoperability and Safety

EN 15624 is a cornerstone of railway safety and interoperability. By standardizing the performance of empty-loaded devices, it ensures that wagons from different operators and countries have predictable and compatible braking characteristics. This is essential for assembling long, heavy freight trains where the braking performance of each individual wagon contributes to the overall safety and stability of the entire consist. The standard directly supports the Technical Specifications for Interoperability (TSI), particularly for the ‘Wagons’ (WAG) subsystem, by providing a clear technical solution for achieving safe and efficient braking across a wide range of load conditions.