The electric axles from SAF-HOLLAND have made a very promising start into the test phase with real-world transport applications: The SAF TRAKr regenerative braking axle and the SAF TRAKe trailer axle with auxiliary electric drive are currently undergoing intensive testing around the world – with positive initial user experiences and new findings for further development.
First presented at the IAA Commercial Vehicles 2018, electric axles from SAF-HOLLAND have since gone through many further development steps. SAF TRAKr and SAF TRAKe use regenerative braking to lower the emissions and fuel consumption of the overall vehicle. In addition, SAF TRAKe uses the stored energy to support the main drive of the tractor unit, for example on hills or in difficult road conditions. Both axles are currently undergoing rigorous testing in real-world operation: While the SAF TRAKr is on the road in Germany and France, the SAF TRAKe is being tested in France as well as in South Africa, the USA and Switzerland.
Demand for more test vehicles
“The first feedback from the drivers and fleet managers has been very positive, and there is increased demand for equipping more test vehicles with the electric axles,” summarises Olaf Drewes, Director Group Innovation EMEA at SAF-HOLLAND. The SAF TRAKr regenerative braking axle is particularly popular: “The drivers are highlighting how much more comfortable it is to drive with the refrigeration unit running purely on electric power.”
The preferred applications for the electric axle are refrigerated vehicles in which the refrigeration units can run fully electric on a temporary basis. This extends the service life of the individual components. In addition, purely electric operation avoids or reduces noise and exhaust emissions. This allows semi-trailer trucks to meet all legal requirements, including night-time refrigerated transports for inner-city deliveries.
The test vehicles, which are currently on the road worldwide in real-life situations, are supporting the progress of the electric axles towards production maturity. “The test results are supplying us with important information regarding the use and application profile of SAF TRAKe and SAF TRAKr,” explains Olaf Drewes. The recorded data are continuously compared to the design criteria for the individual components and used in the further development.
Coordinated overall system
For the modular construction of its e-axles SAF-HOLLAND relies, among other things, on cooperation with external partners. The operating strategy and components are configured to be ideally matched, allowing the system to run smoothly.
Many components are already permanently integrated into the electric axles. This allows trailer manufacturers to install the trailer axles easily and use standard interfaces. Maintenance is also simple and cost efficient: The drive unit does not have to be removed for uninstalling the wheel ends and wheels. Wear parts such as brake pads or brake discs are identical to the components of non-driven axles from SAF-HOLLAND to ensure and simplify spare parts supply.
Modular structure of the electric axles from SAF-HOLLAND
The SAF TRAKr uses a high-voltage generator module for electric regenerative braking, with a maximum power of 26 kW by design. The SAF TRAKe is a trailer axle with regenerative braking and an auxiliary electric drive (maximum power 120 kW) for more traction and stability of the semi-trailer truck. Both axles are designed for axle loads from 9 to 10 t. They are also available with different disc brakes for 19.5″ and 22.5″ tyres and with different air suspensions such as SAF INTRA or SAF MODUL.