Guideline No 031 for E-axles on heavy trailers

Why was this guideline introduced?

Until now, it was not possible to grant a WVTA for O3 and O4 trailers equipped with a dynamo or regeneration axle. The reason was that Annex II of Regulation (EU) 2018/858 did not yet contain specific requirements for areas such as in-use electrical safety and braking systems. 

Although the necessary technical requirements have already been developed, their formal publication and implementation in European legislation will take time. To avoid delaying innovations that can contribute to reducing CO₂ emissions, a consensus was reached within the European Forum for the Exchange of Information on Enforcement of EU vehicle legislation on an early, harmonised approach. Based on this agreement, RDW has published Guideline No. 031. 

What does Guideline No 031 cover?

The guideline sets out the additional technical and administrative requirements for granting type approval to O3 and O4 vehicles equipped with a dynamo or regeneration axle. It provides manufacturers with a transparent assessment framework for incorporating this technology into a European type approval. 

A dynamo axle generates electricity from the rotational movement of a trailer’s wheels while driving. The recovered energy is stored in a battery and can subsequently be used to power onboard systems, such as an electrically driven refrigeration unit. 

What does this mean for manufacturers?

With the publication of Guideline No 031, manufacturers can now include dynamo axles in new type approvals or add them to existing WVTAs for heavy trailers. This creates greater clarity in the approval process and enables innovative trailer concepts to be brought to the European market more quickly. 
The guideline also provides increased legal certainty by clearly describing the documentation, testing and technical evidence required for RDW’s assessment. 

What are the benefits?

The use of dynamo axles makes it possible to recover energy during driving. This energy can then be used to power electrical systems on the trailer. In refrigerated trailers, for example, the technology can replace a separate diesel-powered refrigeration engine. This can result in:

• Lower fuel consumption;
• Reduced CO₂ emissions;
• Lower particulate matter emissions;
• More efficient use of energy. 

For manufacturers, this creates new opportunities to develop and market innovative, more sustainable trailer solutions that support the transport sector’s transition towards lower emissions. 

Supporting innovation through a harmonised approval framework

Through Guideline No 031, RDW supports the early application of dynamo axle technology within a harmonised approval framework that reflects the direction of upcoming European legislation. This approach, endorsed by the European Forum, helps provide clarity for manufacturers during the transition towards the new regulatory requirements.

RDW has been involved in the international process leading to the development of the technical requirements and continues to share its knowledge and experience with stakeholders. By combining practical insights with regulatory expertise, RDW seeks to contribute to the safe and efficient introduction of innovative vehicle technologies in line with future legislation.