Advanced bolt securing technology enhances railway safety
The continued development of modern railway networks has placed greater demands on the reliability of every component used in rail infrastructure and rolling stock. Among the most important of these are bolted joints, where maintaining preload under constant vibration and dynamic loading is essential for safe, dependable operation.
To address these demanding conditions, BMG supplies the Nord-Lock bolt securing system throughout Africa. This system – based on advanced wedge-locking technology – is engineered to secure bolted joints exposed to severe vibration and dynamic forces, helping to improve operational reliability while reducing maintenance requirements.
“Railway applications demand fastening systems that remain secure throughout their service life,” says Maryna Werner, Fasteners Sales Manager at BMG. “Bolt loosening on railway infrastructure or rolling stock can have costly consequences and may compromise safety. Selecting the correct bolt securing solution is therefore critical, particularly where trains operate at high speeds under continuous vibration and strain.
“The Nord-Lock X-series has been developed specifically for safety-critical applications, including railway bogies, coupling devices, brake systems, rail dampers and housings. By preventing both spontaneous bolt loosening and slackening, the system helps maintain secure bolted joints, reducing the risk of equipment damage, while enhancing personal safety.”
For rail and mast bonds, signal bonds and contact splices, BMG recommends the use of NLX10, NL10ss and NL12ss washers. An important advantage of fitting Nord-Lock washers to contact splices is that re-tightening is not required after installation. This reduces maintenance interventions, minimises downtime and helps eliminate hook-up incidents.
Performance testing has demonstrated that the X-series washers meet specification under arduous operating conditions, with no slip occurring. In addition, no hook-up incidents have been reported on contact splices fitted with Nord-Lock washers.
The effectiveness of the Nord-Lock X-series lies in its multi-functional design. The wedge-locking principle prevents spontaneous bolt loosening, while an integrated spring effect compensates for preload loss resulting from settlement and relaxation. Together, these features ensure that the required preload is maintained even under the severe vibration levels generated by rail traffic.
Each washer pair incorporates cams on one side and radial teeth on the opposite side, securing the joint through tension rather than friction. During tightening, the conical washers flatten and the serrations engage the contact surfaces. Because the cam angle exceeds the thread pitch, rotation of the fastener is prevented. As the joint settles after tightening, the spring effect immediately compensates for preload loss, maintaining the integrity of the bolted connection.
This combination of wedge-locking and spring-action technology provides continuous protection against vibration, dynamic loading, settlement and relaxation, ensuring dependable fastening performance throughout the life of the assembly.
Installation and removal can be carried out quickly using standard tools, while independent TÜV certification confirms compliance with recognised international quality and safety standards.
The BMG team supports this range with technical support to determine the most appropriate fastening solution for each application.
The company’s specialists assess joint dimensions, loading conditions and tightening methods before calculating the optimum bolt preload to maximise reliability and service life.
The Nord-Lock securing washer range, distributed and supported by BMG throughout Africa, is the only wedge-locking washer brand to carry the CE quality mark, demonstrating compliance with stringent international safety and quality requirements for industrial applications.
