DIN 25201-4:2026-09 - Draft

What is DIN 25201-4 about?

DIN 25201-4 specifies requirements and recommendations for securing bolted connections in railway vehicles. It supplements the requirements of DIN EN 17976 and supports designers in selecting suitable locking measures for mechanical and electrical bolted connections.

The aim of the standard is to ensure the resistance to self-loosening, functionality and fatigue strength of bolted connections under the typical loads encountered in railway vehicle engineering. It takes into account both mechanical locking elements as well as adhesives and test methods.

What content does the standard cover?

DIN 25201-4 describes locking measures for bolted connections and includes specifications for the selection, testing and assessment of different locking systems. It also covers verification methods against self-loosening as well as aspects of fatigue strength.

Topics covered at a glance:

• Securing bolted connections in railway vehicle engineering
• Locking elements and bolt-locking devices
• Resistance to self-loosening under dynamic transverse loading
• Test methods for secured bolted connections
• Self-loosening and loss of preload
• Fatigue strength of transversely loaded bolted connections
• Anaerobic liquid adhesives for thread locking
• Verification methods for rare high transverse loads

Why is the standard relevant in practice?

Bolted connections in railway vehicles are often exposed to dynamic loads, oscillations and vibrations. DIN 25201-4 helps users select suitable bolt-locking solutions and verify their effectiveness.

The specifications on resistance to self-loosening, vibration testing of bolted connections, preload losses and the selection of suitable locking elements for highly stressed applications in railway vehicle engineering are particularly relevant. In this way, the standard contributes to the operational reliability and failure safety of railway vehicles and their components.

What changes have been made compared with the previous edition?

Compared with DIN 25201-4:2021-11, the draft has been extensively revised. The most important changes include:

• Alignment with the current state of the art as well as European and international regulations
• Updating of terms and integration of terms from DIN EN 17976
• Replacement of the term “risk classes” with “safety needs”
• Revision of the requirements for bolted connections and locking measures
• Incorporation of content and overviews from DIN EN 17976
• Addition of a new annex comparing terms and symbols used in DIN 25201-4 and DIN EN 17976
• Editorial revision of the document

Target audience

• Designers in railway vehicle engineering
• Manufacturers of railway vehicles and components
• Development and calculation engineers
• Testing and approval bodies
• Specialists in strength and joining technology
• Operators and maintenance managers in the railway sector