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Automatic Transmission: New Freedom with 8 Gears

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Starting this year, the latest generation of the 8-speed automatic transmission will be used in the first customer vehicles to support the transition to electric mobility.

Andreas Neemann,

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.

At the Saarbrücken location, everything is set for the volume production of the fourth generation of the ZF 8HP. This represents an important step for ZF in the mobility revolution. The Group has designed the latest version of its 8-speed automatic transmission for passenger cars as a versatile modular system which allows vehicle manufacturers to comprehensively and flexibly electrify their models based on demand.

With the plug-in hybrid variant in particular, long ranges can be driven in purely electric mode. As a result, the 8-speed automatic transmission 8HP helps to reduce the CO₂ limits of fleets and prepares the transition to pure electric mobility.

For the new generation, ZF modernized its automatic transmission fundamentally. The goal is to enable the comprehensive electrification of passenger car model fleets with a modular drive solution for the front-longitudinal driveline. "Plug-in hybrid electric vehicles that operate almost exclusively on electric power in everyday use – which we demonstrated a few years ago with our 'EVplus' concept – will soon become reality with the fourth generation of the 8HP and this innovation makes us best-in-class," explains Markus Schwabe, Head of the Electrified Powertrain Systems Product Line.

"Plug-in hybrid electric vehicles that operate almost exclusively on electric power in everyday use – which we demonstrated a few years ago with our 'EVplus' concept – will soon become reality with the fourth generation of the 8HP and this innovation makes us best-in-class."

Markus Schwabe, Head of the Electrified Powertrain Systems Product Line

Every millimeter counts

In order to be able to offer the OEM as many advantages as possible, ZF engineers have once again significantly increased the degree of integration and optimally utilized every millimeter of installation space. This is particularly the case with mild hybrid and plug-in hybrid variants (PHEV). With the PHEV version, powerful electric motors integrated into the transmission housing enable purely electric driving performance of up to 160 kilowatts and a torque of 450 Nm – almost doubling compared to the previous generation. This puts PHEV vehicles with the new 8HP on a par with pure electric vehicles: Depending on the manufacturer and the battery size used, pure electric ranges of over 100 kilometers are possible. These cars could therefore complete a large part of the average daily driving distances (in Germany) in purely electric driving mode. The emission savings are remarkable: Compared with a purely conventional drive of the 8HP predecessor variant, a plug-in hybrid with the new 8HP generation emits up to 70 percent less CO₂ according to Worldwide Harmonized Light Vehicle Test Procedure (WLTP).

Modular Kit for hybrids

Higher performance, less weight

ZF has now also integrated the power electronics into the transmission housing of the hybrid variants. This simplifies installation considerably for vehicle manufacturers, as external cable connectors or special housing elements are no longer necessary. This not only improves installation flexibility, but also the system weight: The PHEV version of the new 8HP is 6.5 kilograms lighter than its predecessor. The transmission experts have also significantly reduced the volume and weight of key components – by almost 50 percent in the power electronics, for example, and by 42 percent in the mechatronics.

At the same time, the performance data of the new transmission generation is pointing upwards and, with an overall performance of 550 kilowatts and a torque of 1,000 Newton meter, also exceeds the predecessor versions.

Flexible drive solution for the transition to electric mobility: ZF is preparing the volume production of the fourth generation 8HP.

Production ramp-up

Immediately after the announcement of the new generation in 2019, ZF had already received long-term orders worth millions from renowned international automotive manufacturers for its flagship transmission. The transmission was developed in Friedrichshafen. With the start of volume production, the Group is also right on schedule. Components and systems are supplied by other ZF locations, with the electric motors coming from Schweinfurt and the power electronics and transmission control from Auerbach. First customer vehicles were available as of mid-year. A first assembly line, which is highly automated and very flexibly designed, will then continuously increase capacities. ZF will produce a six-digit quantity per year. The plant in Saarbrücken has already planned another assembly line. Starting in 2025, the ZF plant in Gray Court (USA) will also begin production of the new 8HP generation.