Automotive Engineer

Whether you drive off-road or on a racetrack, all-wheel drive gives greater stability and traction to make driving safer. There are now many variants of the technology, from permanent traction systems that split torque equally between front and rear wheels to more intelligent torque vectoring systems that can split power between both the front and rear wheels of a vehicle as well as from left and right depending on demand.

It was Paul Daimler, son of automotive industrialist Gottlieb Daimler, who introduced the technology to passenger vehicles. 

The oldest of five children, Paul Daimler studied at Stuttgart’s technical university before beginning his engineering career at his father’s company, Daimler Motoren-Gesellschaft.

Daimler started work in 1887 and swiftly rose through the company. After a three-year secondment to the Austrian Daimler Motoren-Gesellschaft in Wiener Neustadt as technical director, he returned to Germany in 1905 as chief designer and a member of the board.

Daimler worked on everything from motorcycles to aircraft engines during his career, but his first all-wheel drive system design draft was produced in 1904. Military vehicles used the technology first, as it gave them greater traction and manoeuvrability on rough terrain, but in 1907 the technology was transferred to a passenger vehicle – the Dernberg-Wagen.

The vehicle was specifically designed for use on the difficult terrain of South-West Africa, and used by the secretary of state for the colonial office in what is now known as Namibia.

The country had little in the way of a road network, and those that were available were not much more than dirt tracks. Daimler’s all-wheel drive system was well suited to the task of transporting officials safely.

The Dernberg-Wagen was 4.9m long and 2.7m tall with a track width of 1.42m, and weighed more than 3,600kg. It needed the extra traction the drivetrain offered.

Daimler’s system was complex. The permanent all-wheel drive used a shaft to connect it to the centrally installed four-speed gearbox. From there propshafts transferred torque to the front and rear axle differentials, which then used bevel gears to split the power to each wheel.

Because of the Dernberg-Wagen’s sheer weight its 26kW, 6.8-litre four-cylinder engine could only power the vehicle to a maximum speed of 40km/h.

But its offroad ability was undeniable – the vehicle could travel up a 25% incline with no difficulty.

As the vehicle was destined to spend much of its working life away from flat, well-maintained roads, durability was an important challenge for Daimler’s system.

The engineer took special precautions to keep sand and dirt out of components. Lubricating grease was used liberally to stop fine particles of airborne sand causing damage. The front axle was especially difficult to protect.

Because of heavy impacts on the components during operation, Daimler couldn’t use traditional ways of protecting the bevel gears on the wheels. Instead he shrouded the system with a cylindrical metal sleeve.

There was a drawback. The design limited the steering capability of the Dernberg-Wagen to just 23°, but Daimler’s solution was almost as intriguing as his all-wheel drive system. He introduced a steering mechanism on the rear wheels.

Before being sent to South-West Africa, the vehicle was tested for 1,677km in Germany, during which a colonial office report said: “The vehicle was driven into a sandpit, in which it sank well up to its axles in the sand, but from which it managed to free itself with ease despite gradients of 21%.”

In its first two years of service, the Dernberg-Wagen covered 10,000km, but it didn’t remain all-wheel driven.

Daimler’s system worked but was complex – which made it impractical – so the Dernberg-Wagen was later converted to rear-wheel drive.

But Daimler’s technology has since been adapted to suit nearly every vehicle class. Today it isn’t just the military that use all-wheel drive, nor is it simply the choice of farmers in rural areas. All-wheel drive helps people in day-to-day driving situations, giving vehicles better traction, stability and safety.