ZF develops new 8-speed auto

Gearbox manufacturer ZF unveiled its latest eight-speed automatic gearbox at the recent Vienna Motor Symposium, a design that promises to reduce fuel consumption and at the same time transmit more power to the wheels than its current six-speed boxes. With the extra cogs on board, the new gearbox improves mileage rates by 6% over the second generation six-speed transmission popular with numerous makes including the likes of BMW and Aston Martin. Compared to a five-speed transmission, which is still widely used today, the consumption reduction amounts to almost 14%.

Two innovations are mainly responsible for the improved performance. The design incorporates four planetary gear sets and five shift elements. Only two shift elements are opened in each gear which leads to considerably lower drag losses. Besides the improved efficiency, the transmission also features a higher total ratio. Further, modern torsional vibration damping systems in the torque converter also have a positive impact on consumption and CO2 emissions.

ZF has also designed the gearbox as a modular unit that can be used in a number of configurations including AWD without the need to change the basic transmission concept. We’re also likely to see the gearbox appear in future hybrid models, similar to the systems developed by Mercedes-Benz and BMW, which utilize a crankshaft starter generator. Conventional hybrids that use a parallel configuration like the Toyota Prius can also benefit from the new design.

The next several months will be interesting to see whether traditional automatics will remain more popular than the latest dual-clutch systems being rushed to market by most of the major carmakers. With the number of gears growing each year for new transmissions, we wonder if gearbox manufacturers will continue to try and outdo each other just like the razor blade companies.