New transmission tech could prove game-changing for electrified trucks

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Belgian company Mazaro is developing potentially disruptive transmission technology targeted at the commercial vehicle segment. According to Co-Founder and Director Filip De Mazière, it offers significant energy, emission and cost savings in vehicles with a dynamic driving style—fast and slow, loaded and unloaded. “Nowadays the market is looking for emissions reductions but the current systems are completely out-designed to the maximum,” says De Mazière. “We see the need for something completely new.”

A fresh approach: two takes

Applying this fresh approach to transmission design, the start-up is developing two different types of transmission. The first is a reversible variable transmission (RVT), offering an overdrive speed ratio of 2.6 over standstill to reverse without traction interruption. Initial findings suggest that in city buses, this could slash fuel consumption and emissions by 11-19% compared to an automatic transmission (AT). Its compact form is 25% lighter than most ATs, and offers an 11% cost saving, cutting out the need for a clutch, a torque converter and gears. Overall efficiency is estimated at 94.9%.

At its heart is a single mechanical system based on two sets of wheels that roll over one another. “This pure rolling is completely different from belt CVTs (continuously variable transmissions),” says De Mazière. The wheels are made to a certain curve: not circular but a special patented shape that eliminates drill slip and results in higher efficiency. As the rolling surfaces come together with no slip, the oil film in between the cones stays relatively cool and the viscosity remains high. This separates the steel surfaces from each other, meaning there is never any steel-on-steel contact. The oil, which doesn’t heat up, has an almost unlimited life.

“Maintenance should be completely eliminated,” he promises. “The overall cost is lower because there are fewer components.” This unit is intended for use with an internal combustion engine (ICE) either on its own or combined with an electric system as in a hybrid setup.

For all-electric vehicles, Mazaro is working on a single stage variable transmission (SVT) which it claims is the first CVT capable of handling high torques from heavy-duty vehicles. This unit features one set of wheels, compared to the two found in the RVT, and overall efficiency is estimated at 97.5% Initial testing in an electric 3.5-tonne truck found it offered 16% more driving range and 50% higher top speed.

Maintenance should be completely eliminated. The overall cost is lower because there are fewer components

Both the RVT and SVT units are designed to keep the engine or electric motor on its best efficiency curve all the time—at low or high power, as the vehicle accelerates, drives up hill or at constant speed. “By controlling the transmission to make sure the driveline is always optimised, you provide the best possible efficiency of the system,” explains De Mazière.

Coming soon

While the technology has potential to improve performance across many vehicle segments, those that operate in a diversified style stand to benefit the most. That means city buses, delivery trucks running in dense traffic, construction trucks, terminal tractors, agricultural tractors, and electric trucks and buses. With the promise of fewer components and lower costs, they could go down well in price-sensitive markets.

Mazaro invehicle test results

“Transmissions have taken on more gears and become increasingly sophisticated,” says De Mazière. “What started with four speeds in previous days was replaced by five, six and sometimes eight to ten speeds. More gears also means more clutches or synchronizers and thus more cost. The RVT and SVT offer and infinite amount of ratios with far fewer components.”

The technology is still in development, and the company consists of a small team with limited budget and equipment. “Developing and testing the software is a matter of engineering time. In addition, the test benches themselves had to be defined, constructed and tested. But developing the Mazaro technology goes much faster than the development of a double clutch transmission,” he tells Automotive World.

A demonstration electric truck with the SVT is currently operating on the road, and there are three different projects ongoing that will lead to working prototypes in 2021. Series production is planned by early 2023. Mazaro itself handles the development, engineering and testing, and outsources production to partner companies.

 

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