Regenerative Braking Axle In Production Since Late 2022

The use of electrified trailer axles is becoming increasingly important for low emission transports, such as for refrigerated semi-trailers and inner-city applications. The Vehicle Energy Consumption Calculation Tool (VECTO) and other legal regulations are further innovation drivers for electric technologies: More than 50 zero emission zones are planned in Europe in the near future, including in Berlin, Paris and London. Stricter noise pollution standards also encourage manufacturers to produce vehicles that are significantly quieter. To limit global warming as planned, CO2 emissions have to be lowered by up to 95 per cent by 2050. “We see great opportunities for electrified trailer axles here: They reduce CO2 and noise emissions to meet legal requirements, for example for refrigerated night-time deliveries in urban areas. The electric axles also meet the industry trend towards ‘greener transport’,” says Olaf Drewes, Director Group Innovation Trailer at SAF-HOLLAND. The transport industry is undergoing great changes. The issue of CO2 emissions is becoming increasingly important due to current legislation for commercial vehicles, such as VECTO. With product developments like SAF TRAKr, SAF-HOLLAND offers a solution that stays abreast with these changes and helps to minimise CO2 emissions.

SAF TRAKr lowers emissions and fuel consumption

The SAF TRAKr trailer axle uses regenerative braking to reduce the emissions and fuel consumption of the whole tractor-trailer combination. To do this, the centrally positioned high-voltage generator unit converts the kinetic energy of the trailer into electrical energy. The generated energy is stored in a Li-ion battery and then used to run the electrical units in the trailer, such as refrigeration units or pumps, on electricity alone.

The main areas of application are refrigerated semi-trailers or container chassis for refrigerated containers, food tankers, silo trailers, walking floors or platform vehicles with a crane. For the drivers, the purely electrical operation of the refrigeration unit provides appreciable added comfort on the road, as they are exposed to significantly lower noise emissions. The regenerative braking axle is manufactured at the SAF-HOLLAND factory in Bessenbach, northern Bavaria. After the launch on the European market, sales of the SAF TRAKr started in Australia and New Zealand in 2023. Vehicles equipped with the SAF TRAKr are already on the road in these markets. In other regions, such as North America and India, the trailer axle is currently being used in test vehicles.

Easy maintenance and reliable spare parts supply

The operating strategy and the individual components of the SAF TRAKr are perfectly coordinated to ensure maximum flexibility and ease of maintenance. Numerous components are permanently integrated into the electric axle. This allows trailer manufacturers to install or retrofit the SAF TRAKr with little effort using standard interfaces.

Maintenance is also easy and cost-efficient: Neither the centrally installed gearbox with the flanged-on generator nor other HV components have to be removed when wheel ends and wheels need to be detached. Wear parts such as brake pads or brake discs are identical to the components of non-electrified SAF-HOLLAND axles. This makes spare parts supply easier and more reliable.

SAF TRAKr: modular design offers flexibility

The SAF TRAKr uses a high-voltage generator module for electric regenerative braking, with a maximum design output of 17 kW. The axle is designed for axle loads from nine to ten tons and offered as a water cooled or air cooled variant.  It is available with different disc brakes for 19.5″ and 22.5″ single tyres and for the SAF INTRA suspension system. A version for double tyres is currently uder development. The SAF TRAKr will also be available in combination with the MODUL suspension from the middle of 2024. The modular structure is specifically designed for the different requirements of the EMEA, Americas and APAC economic regions. SAF-HOLLAND is cooperating with external partners for the regenerative braking system.

The generator runs independently of the tractor unit while the vehicle is in motion and shuts off during ABS braking or vehicle dynamics control events in order to ensure driving stability. Many vehicle manufacturers are currently working on implementing the European type approval, which helps to simplify the registration process.

The generator is also deactivated at vehicle speeds below 15 km/h, so the required start-up torque and therefore the fuel consumption of the tractor unit are not increased during these phases. The charging options are energy generation by the axle while driving and charging from an external power supply during standstill, for example during loading or unloading.