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Tomorrow’s Automatic Transmission is a Team Effort

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The new 8-speed automatic transmission for passenger cars is going into series production. Planned for hybrid and combustion engine use, this is an example of ZF’s successful development and production logistics.
Andreas Neemann,
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Andreas Neemann wrote his first ZF text in 2001 about 6HP transmissions. Since then, the automotive writer has filled many publications for internal and external readers, showcasing his passion for the Group's more complex subjects.
Phew! It's like crossing the finish line of a marathon. After years of intensive preparation, ZF is now starting series production of its new 8-speed automatic transmission for passenger cars. Now in its fourth generation, this transmission is a milestone for Next Generation Mobility. Even though it is assembled in Saarbrücken, many of its central components come from other, specialized ZF locations.

Electronic Control Units From Auerbach, Bayreuth, Klášterec

Electronic Control Units From Auerbach, Bayreuth, Klášterec

As with the transmission in its entirety, the iTCU (integrated Transmission Control Unit) component has changed and improved when compared to the previous version. A completely new, more powerful chip has been installed. By integrating functions into mechatronics, engineers were able to dispense with some components. The unit now weighs 24 percent less while being considerably more powerful. The control software was developed at ZF Friedrichshafen’s R&D center in cooperation with the software centers in Hyderabad, India, and Pilsen, Czech Republic. To ensure its safe functioning, the control software needs to be provided with reliable sensor information. Many of the sensors are installed in the iTCU itself. They come from ZF’s Bayreuth, Germany, location and are pre-assembled there and delivered to ZF’s nearby Auerbach plant including the wiring harness. Already in 2019, the Auerbach plant ordered new systems to prepare the current SOP. Today, the production of the iTCU of 8HP comprises nine assembly and test lines. The plant is prepared for a call-off increase.
Another important component are the power electronics, which coordinate the high-voltage current flow for the drive in the automatic transmission hybrid variants. For the latest generation, it is much more compact and has been integrated into the transmission housing for the first time. The power electronics for the new 8-speed automatic transmission are produced in Klášterec, Czech Republic.
Assembly line for 8HP

Assembly line for the new 8-speed automatic transmission in Saarbruecken

A Perfect Start in Schweinfurt and Pančevo

A Perfect Start in Schweinfurt and Pančevo

Traditionally, starting elements of ZF automatic transmissions come from Schweinfurt. They have grown more complex in the past ten years, because in addition to the "classic" components of torsional dampers and torque converters, electric motors are increasingly viewed as the main starting element. Many of the 8-speed automatic transmission units, which will be manufactured in the coming years, have to work in a purely electric manner and with zero emissions in mild hybrid and plug-in hybrid vehicles. The plug-in hybrid variants of the fourth-generation automatic transmission therefore have much more powerful electric motors: 160 kW power at a torque of 450 Nm is sufficient to move even full-size luxury sedans efficiently over longer distances electrically.
Partial view of the transmission housing

Schweinfurt, Pančevo: A perfect start

Schweinfurt, Pančevo: A perfect start

Even with an increased performance, the electric motor is still integrated into the same installation space as its predecessor. In addition to Schweinfurt, electric motors are also produced in the ZF plant in Pančevo, Serbia. The two plants have almost identical production lines, which allows ZF to be flexible and respond quickly.

Smart Torsional Dampers

Smart Torsional Dampers

Long before the start of production for the new transmission, engineers in the Schweinfurt location started to work on the torsional damper design. The torsional damper can now be combined with a wide variety of combustion engines — making it a kind of adapter to the engine. Since the automatic passenger car transmission is used all over the world, it must be provided in many different variants, and the torsional damper helps to realize this variety as efficiently as possible. In addition, for the mild hybrid variants consisting of torque converter and electric motor, a compact unit that is easy to integrate into the transmission should be used. The objective was also to offer as many variants as possible without making the production unnecessarily complex.
E-Motor assembly: putting together stator and rotor

Most Advanced Assembly in Saarbrücken

Most Advanced Assembly in Saarbrücken

Creating space for the start of volume production was one of the primary concerns at the main assembly location in Saarbrücken, where individual parts of the transmission are also produced. In addition to the production launch of the fourth generation, the production of the previous version of the automatic transmission should continue to run at full speed. By outsourcing the transmission housing production, space was created for two new assembly lines, one of which is now productive. Another challenge is making processes safe for higher volumes — especially since a customer call-off increase is expected for the end of the year 2022. Investments in machinery – for example, the final inspection – are also carried out concurrently with the increase in production figures. The plant has already meticulously planned the ramp-up phase and obtained approval from its key customers.
Assembly with the latest technology

Technology and Production: Planned Down to the Last Detail

Technology and Production: Planned Down to the Last Detail

The new 8-speed automatic transmission is now produced with increased automation. For example, mechatronics are now installed through automated systems. This increased automation also addressed changes required for the installation space. While having almost identical external dimensions, the new transmission has a lot more going on inside. Previously, the power electronics were connected externally. Now, for all hybrid variants, ZF has integrated them into the transmission housing. This makes the installation process for vehicle manufacturers much easier because external cable connections or special housing elements are no longer necessary. All variants of the fourth-generation 8-speed automatic transmission – for internal combustion engines, mild hybrid vehicles and plug-in hybrids – have identical dimensions and fit into the same transmission housing. All these advantages result from the pooling of specialist knowledge in development and production within the ZF network.
Assembly line for inverters in the Klášterec plant