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At the Center of Attention: Efficiency

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Tags: Efficiency

After eleven years, ZF presents the second generation of its fully automatic city bus transmission EcoLife. A large number of innovations in hardware and software make this classic driveline fit for the years to come.
Frank Thoma, October 18, 2019
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Frank Thoma has been corporate editor at ZF since 2011. With a degree in journalism, he has been planning, writing and editing articles for all of the company’s internal, external media.
Man-made climate change, with all its negative effects, is currently one of the greatest challenges facing humanity. Part of the blame for climate change lies with climate gases emitted by private and public transport, including carbon dioxide. Buses, in particular, form the backbone of public mobility worldwide. This is no surprise, since buses allow you to quickly create a comprehensive mobility infrastructure, with extremely flexible vehicles that are inexpensive to operate. Even if it is desirable to quickly electrify all bus fleets for environmental reasons, the current high acquisition costs and lack of infrastructure present major obstacles.

China is currently way out in front in terms of the electrification of local public transport. According to the findings of the Bloomberg New Energy Finance (BNEF) report presented in the spring of 2019, 421,000 of the 425,000 electric buses worldwide were in service just in China at the end of 2018. The analysts of the BNEF report put the number of purely electric buses in Europe at 2250 at this time.

More efficiency for conventional bus drives

More efficiency for conventional bus drives

Precisely because many city buses will still be powered by an internal combustion engine in the medium term – either exclusively or together with an electric motor as a hybrid – these buses must be as clean as possible. In addition to low-emission engines, the transmission offers another important starting point for noticeably reducing fuel consumption and thus CO2 emissions. “Combustion-powered buses remain a central component of local public transport and long-distance travel. It is therefore important to make a contribution to reducing emissions and increasing efficiency. The market demands maximum comfort and the best performance possible – and that’s what we have achieved with the new EcoLife 2,” says Dr. Andreas Grossl. At ZF, he is responsible for axle and transmission systems for buses.

EcoLife 2 – the up and coming standard for city bus transmissions

EcoLife 2 – the up and coming standard for city bus transmissions

When ZF rolled out its newly engineered 6-speed automatic transmission EcoLife for city and intercity buses in 2008, it consumed up to six percent less fuel than its predecessor. Now the engineers at ZF have further engineered and improved this market-dominating classic in many areas. This makes the new fully automatic EcoLife 2 transmission even more resilient and lightweight, as well as more economical. Attentive passengers will notice that buses equipped with this transmission are quieter due to lower engine speeds and that the ride is even more pleasant thanks to shifting that is both fast and smooth. This improvement in comfort can be traced back to a torque converter with a new torsional damper.
The most important components of the 6-speed automatic transmission EcoLife 2.

More efficiency thanks to many changes to the hardware and software

More efficiency thanks to many changes to the hardware and software

In addition to comfort, costs are an important issue for bus fleet operators. Fuel economy is front and center here. Thanks to numerous technical modifications, the EcoLife 2 was able to reduce fuel consumption by up to three percent compared to its predecessor. The start/stop function of all six EcoLife 2 variants is one of the features responsible for this, representing a huge improvement for city buses. ZF offers its new 6-speed automatic transmission for input torques between 1000 and 2000 newton meters. A further contribution to fuel and emission reduction is made by the transmission control in conjunction with the hardware: the EcoLife 2 now also features a fuel-saving rolling function in coast mode. And because it matters whether a city bus is on the flat or in hilly terrain, the customer can now request that the EcoLife 2 also be equipped with a variety of characteristic curves for setting off.

Focus on maintenance

Focus on maintenance

In order to also reduce service costs through increased maintainability, ZF engineers have fundamentally overhauled the cooling system of the transmission. The transmission heat exchanger, which was located on the side of the transmission housing of the first EcoLife, has disappeared. With the EcoLife 2, the transmission heat exchanger and retarder heat exchanger have now been combined, with the cooling capacity remaining the same. These and other structural changes reduce the weight of the EcoLife 2 by up to 20 kilograms. With the “ZF DriveLife” offer, fleet operators will have the option of predictive maintenance in the future, with the tool constantly providing information on the state of the transmission. It will allow irregularities to be quickly detected and eliminated before expensive repairs and extensive downtimes come to pass.
In the start-stop version, the EcoLife 2 in the version for input torques of 1000 Newton meters is 20 kilograms lighter than its predecessor.

Thanks to its many improvements, the EcoLife 2, which was launched on the market in the first half of 2020, has what it takes to contribute to making local public transport as environmentally friendly as possible in the coming decade. Grossl has this to say about it: “Those responsible in municipalities all over the world are confronted with passengers demanding more comfort and legislators calling for more environmental protection. Our EcoLife 2 allows both sets of stakeholders to be satisfied.”

Further technical details on the new 6-speed automatic transmission EcoLife2 can be found here.

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