SAF-Holland talks e-axles, fuel efficiency

Power regeneration via recuperation is possible with the SAF TRAKr axle jointly developed by SAF-Holland and Carrier Transicold.

The use of electrified trailer axles, according to SAF-Holland, is becoming increasingly important for low emission transportation, such as for refrigerated semi-trailers and inner-city applications.

Another innovation driver for the electric technology are the legal regulations: More than 50 zero emission zones are planned in Europe for the near future, including in Berlin, Paris and London. Stricter noise pollution standards also encourage manufacturers to produce vehicles that are significantly more quiet. 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,” said SAF-Holland Director Group Innovation EMEA, Olaf Drewes. “They reduce CO2 and noise emissions and meet legal requirements, for example for night-time refrigerated transports on inner city routes. The electric axles also cater to the industry trend towards ‘greener transport’.”

Dynamic duo develop e-axle
Equipment specialist, SAF-Holland, is collaborating with cold chain solution provider, Carrier Transicold, on the development of its SAF TRAKr recuperation axle. The international leading company contributes to the smart recovery system of the trailer solution thanks to its axle, which enables the autonomy of the Vector eCool refrigeration unit while driving.

The SAF TRAKr recuperation axle, which commenced series production in 2022, marks an important milestone for SAF-Holland for the future of e-transport: Lower fuel consumption, lower CO2 emissions and less particulate matter, but also better noise protection, more efficient processes and reliable compliance with current legislation. Ultimately, this development helps operators to reduce operational costs and make heavy duty transport more sustainable.

SAF-Holland brought Carrier Transicold onboard as a partner in mid-2020 to ensure optimal performance of the e-trailer axle. The two companies are pooling their expertise in the areas of development, technology, approval, customer support and service.

“We have a very close and dynamic partnership and look with pride at the results of our cooperation so far,” said Christoph Günter, President Europe, Middle East and Africa and Chief Technology Officer (CTO) at SAF-Holland.

This partnership between SAF-Holland and Carrier Transicold aims to provide heavy duty trailer operators with a complete 100 per cent electric system with a plug & play solution in the long term.

“We believe connecting the SAF TRAKr recuperation system to our Vector eCool will strengthen our position as pioneer in ultra-low-emission trailer refrigeration, with a solution that offers autonomous power, no direct emissions, and quiet operations,” said Victor Calvo, Carrier Transicold International Truck & Trailer. “This partnership between two leading companies in the industry results in a high-performance and reliable solution that will offer a wider choice for our customers.”

The SAF TRAKr trailer axle uses regenerative braking to lower the emissions and fuel consumption of the overall vehicle. 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 the refrigeration units, on electricity alone.

The main areas of application are refrigerated semi-trailers, tank trucks and silo trailers. 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 in northern Bavaria.

For maximum flexibility and ease of maintenance, the operating strategy and the individual components of the SAF TRAKr are perfectly coordinated. Numerous components are permanently integrated into the electric axle. This allows vehicle manufacturers to install or retrofit the SAF TRAKr with only little effort while 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 to uninstall wheel ends and wheels. Wear parts such as brake pads or brake rotors are identical to the components for the non-electrified SAF-Holland axles. This makes the spare parts supply easier and more reliable.

The SAF TRAKr uses a high-voltage generator module for electric regenerative braking, with a maximum power of 20 kW by design. The axle is designed for axle loads from nine to 10 tonnes. It is available with different disc brakes for 19.5” and 22.5” tyres and for the SAF INTRA and SAF MODUL suspension systems. SAF-Holland is cooperating with external partners for the regenerative braking systems.

The generator runs independently of the tractor unit and only while the vehicle is in motion, but not during interventions by the ABS braking system or driving dynamics. For reasons of type approval, regenerative braking is currently not yet permitted for adaptive braking. The generator is 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. Charging options are energy generation by the axle while driving (generator operation) and charging from the external power supply during stand- still, for example when the vehicle is loaded or unloaded.

Corrosion protection with special coating
Since Q4 2022, SAF-Holland has been delivering its SAF INTRA axles with the optional zinc-free SAF PREMIUM COATED powder coating. It protects the axles against corrosion damage caused by weather and dirt and gives the vehicles a neat appearance over many years. This gives trucks, tanker trucks and silo vehicles a longer service life and a higher resale value and consequently makes them more economical.

Complex operating conditions – such as road salt in winter or dirt at landfill and construction sites – promote corrosion on the SAF INTRA axles. The damage becomes evident early on, sometimes after as little as two years on the road, in particular on the edges of the SAF INTRA suspension arm. SAF PREMIUM COATED, a multi-stage coating process with powder coating, reliably prevents corrosion.

“We are currently the only axle manufacturer that offers an additional zinc-free coating in the nine-tonne segment,” said Mark Hartmann, SAF-Holland Head of Product Management OU Europe, Middle East and Africa.

The improved corrosion protection extends the service life of the axles and ensures a neat appearance of the vehicle fleet. This allows owners to count on a higher resale value, in particular in the case of high-quality tanker and silo bodies. Fleet operators also benefit from the high coverage and the optimum mechanical properties of the powder coating. In addition, the coated axles are resistant to impact, light, chemicals and extreme temperatures. SAF-Holland offers a 10-year anti-corrosion warranty against corrosion on its SAF PREMIUM COATED axles.

The coating is applied to the axle beam and also to the steering arm for steering axles. Other add-on parts such as brakes or wheel ends are not coated. The benefit of the SAF PREMIUM COATED axles for vehicle manufacturers: The coated axles can be painted over if necessary and can be sold at a surcharge directly ex-factory in the case of expensive bodies such as silo vehicles or tankers. Also, the installation of the corrosion-protected axles is identical to installing standard SAF-Holland products.

The four-layer SAF PREMIUM COATED process optimises the technical properties of the rigid and steered SAF INTRA axles: In the first step, airless blast cleaning prepares the surface of the welded axle beam, breaks sharp edges and removes silicates from the welding process. Then a standard cathodic dip coating is applied to the axle as a basis for the next coats.

In the third stage, the axle is primed with a zinc-free epoxy-resin powder that offers good adhesion and protects against corrosion. The final powder coating on polyester resin basis in colour DB703 Iron Mica Metallic has optimum mechanical properties and gives the axle a high-quality appearance.

“Together with the top coat powder, the zinc-free corrosion protection powder forms a perfectly coordinated protection system,” said Hartmann.

“With the same performance level, it is significantly more environmentally friendly than zinc solutions containing hazardous substances.”

The additional coating of the SAF INTRA axles also has a positive impact on the test results, as the manufacturer indicates: In the salt spray test as per DIN EN ISO 9227, there was no visible corrosion on the surfaces or edges even after four times the test duration of 2,000 hours.

The SAF PREMIUM COATED process is suitable for a number of models from the SAF INTRA series with different suspension arm versions, as well as for standard and offroad applications: for all axle types of the rigid SAF INTRADRUM axles and for the rigid SAF INTRADISC axles with the exception of the electric axles and the hydraulically driven SAF INTRA CD TRAK axles. For steered axles, the special coating can also be applied to almost all variants with disc brakes.

In other news, SAF-Holland announced a change to its Supervisory Board.

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