How ZF Sent a Hybrid Truck to Take on the Desert

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Tags: Motorsport, Emobility

At the 2020 Dakar Rally, the Riwald Dakar racing team will be the first to race a hybrid truck. In cooperation with technology partner ZF, MKR Technology provided its drivetrain. But how did this happen? The team recalls the series of events.

Lars Weitbrecht, January 16, 2020

Lars Weitbrecht originally comes from the music and gaming industry, but in addition to holding a game pad or guitar in his hand, he also enjoys the power of the pen and the feel of the steering wheel.

The final high-stakes stage begins in Haradh and ends in Qiddiya in Saudi Arabia. When the off-road truck of the Riwald Dakar racing team crosses the finish line of the 2020 Dakar Rally on January 17, the vehicle will have traveled 7,856 kilometers through the desert. Regardless of Riwald Dakar’s final ranking in the race, the team is assured a place in history. Riwald Dakar is the first team to enter the Dakar Rally with a hybrid vehicle.

Speed in racing, speed in development

“It’s a really crazy idea,” is what Ralf Boss, Director of Special Vehicle Systems at ZF, thought when the hybrid drivetrain for the Dakar Rally was discussed for the first time. To install an electric motor to provide support in a rally car, and, on top of that, in a 1,000-horsepower off-road monster with all-wheel drive? And then to drive it across the desert?

“Admittedly, we had successfully implemented a similarly crazy idea for MKR Technology six years ago – in the form of a heavy-duty automatic powershift transmission. That was another reason why we wanted to take on the challenge.”

The ZF team was also curious to see how the necessary components would behave in such a harsh environment and what performance they could deliver when put to the test in an endurance race.

“As a matter of principle, we trust our technology,” Boss continues. “The most crucial point in the design process was the decision regarding which components to use and how best to combine them. What really made it a challenge was the targeted timeframe.”

Only about six months remained until Dakar. In motorsports, everything happens much faster than in standard volume production development. For this reason, it was necessary to seek support within ZF at an early stage. “The main reason we were able to keep to the schedule so well was because we were working together hand in hand across divisions, business areas, and organizations,” says Boss.

The vehicle's electric machine is an electric central drive including power electronics, which has been converted for truck use.

Trust and technology

A partnership has existed between ZF and MKR Technology for 30 years. The two companies have come to understand each other and know what really matters. Above all, they have gained experience in setting trends. When the technology company and the MKR team sent the first rally truck with automatic transmission to the starting line in 2014, the competitors were still smirking. More and more rivals are now taking this step as the years progress.

It is thanks to this trust and the capabilities of the development team that the hybrid drivetrain will be part of Dakar 2020.

©Rally Maniacs

To ensure that the driveline can withstand the tough conditions, the hybrid solution is based on proven ZF components.

The project was launched a bit more than six months before the start of the rally. To adhere to the schedule and to ensure that the drivetrain will be able to withstand the harsh conditions of the Saudi-Arabian desert, the hybrid solution is based on proven components. The automatic transmissions and transfer cases have their origins in the commercial vehicle sector and are rally-tested. The electric motor is an electric central drive with power electronics that has been retrofitted for use on a truck.

“We wanted to stay as close to volume production as possible so that we would be able to use many of the experiences from the Dakar Rally in other applications,” says Bernd Aumann. He is responsible for sales and application of Special Vehicle Systems of the Industrial Technology division at ZF.

On the hardware side of the axle drive, the two biggest changes remained the elimination of the standard differential and the development of a new transmission stage. This compensates for the massive differences that the diesel engine and the electric motor exert on the transfer case during revolution. Another new component is the hybrid control unit, including software that has been specially programmed for the rally. ZF gave the electric motor the name CeTrax Lite RS.

“CeTrax Lite RS thus provides an additional 80 kilowatts of power on a permanent basis, 150 kilowatts at peak output and 1,400 newton meter of torque without tearing the axles apart,” says Aumann. The advantage of the additional power became clear on the test track, where MKR was able to consistently cut several seconds from its times with the new drive. In addition to the additional power, the energy recuperation effect of the electric motor is primarily responsible for these faster times, allowing the driver to apply the brakes later and harder and to push the vehicle to the limit for longer.

ZF’s CeTrax Lite RS electric motor provides 80 kW of power in the long term, 150 kW at peak power and 1,400 Nm of additional torque.

The real fun comes at the end

Throughout the entire development process, MKR and ZF stuck together through thick and thin. “There was a brief period of time in which we were unsure whether we would be able to pull it off,” says Mario Kress, team manager and founder of MKR. But thanks to the constant communication between the engineers and the race car drivers, the problems could be quickly identified and resolved. The drive assembly got better and better and made its full potential clear on the test tracks. After only two weeks of testing, the participants were completely convinced, and it was decided that they would go to the starting line with the hybrid for the first time at the 2020 Dakar.

“It was both exhausting and stressful, but the fun comes at the end. We are proud to have met the challenge the project presented to us,” says Aumann. “Now we are curious to see how our drive will perform in the acid test. There will be lots of sand and lots of vibration – which promises to deliver important insights for volume production development in other challenging vehicle types, such as fire trucks.”

“We have managed to make the impossible possible,” adds team manager Mario Kress. And then, with a bit of understatement: “It rolls down the track and does what it’s supposed to do, and we’re all pleased about that.”

E-Power for the Dunes

A world premier at the Dakar Rally: ZF has developed a new hybrid driveline for the most famous off-road race in the world.

Technology

How ZF Sent a Hybrid Truck to Take on the Desert

Speed in racing, speed in development

Speed in racing, speed in development

Trust and technology

Trust and technology

The real fun comes at the end

The real fun comes at the end

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E-Power for the Dunes

E-Power for the Dunes