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With the 8HP transmission generation, ZF established a model range on the market offering considerable progress in terms of fuel savings, power-to-weight ratio, and functionality. A front-transverse transmission derived from the 8HP transmission generation gear set concept leads to higher design costs and to an unfavorable design, contradicting the very restricted installation spaces for front-transverse transmissions. With the transmission concept of the 9HP48 transmission, the advantages of the 8HP transmission generation were successfully transferred to a front-transverse transmission design and, at the same time, all restrictions regarding the installation space were solved. Thanks to its number of gears the high efficiency and the reduced drag torque, the 9HP48 transmission delivers fuel savings of up to 16 percent compared with today's standard 6-speed automatic transmissions with front-transverse installation.

The legislative and market pressure for CO2 reduction and fuel efficient powertrains lead to a variety of automatic transmission concepts in recent years. The CVT technology, the dual clutch technology (DCT) and optimized architectures of torque converter / planetary gear based automatic transmissions (AT), such as 6, 7, and 8 speed ATs entered the market in the last decade. Also different hybrid technologies have entered the market offering further improvement for fuel consumption especially in city driving. Helpful for OEMs and suppliers to flexibly meet market demands proofed the use of modular hybrid solutions. Clear demand to meet were packages of existing vehicles and powertrains with AT and hybrid transmission (HT), e.g. the modular transmission kit based on the ZF 8 speed AT. Hybrid technology is offering fuel efficiency benefits, but there are also reasons for a slow market penetration.

Hardware-in-the-loop (HIL) simulation has become a key technique for the validation of today's automotive electronics. OEMs and suppliers are investing heavily in hardware-in-the-loop equipment and tests. Typically, suppliers test the electronic control unit (ECU) as a component. The OEM on the other hand tests the ECU more from a network point of view. This paper describes the main differences between component and network HIL tests. ZF Friedrichshafen AG has been using HIL test benches since 1985. In order to ensure high quality, especially with respect to network aspects, we not only test the ECUs as components but as part of the network. For that purpose, and to stay on the leading edge of HIL technology, ZF has set up a new test bench for networked HIL testing. The control network contains the driveline and chassis domain.

Extended drain of axle and transmission lubricants has gained wide acceptance in both passenger car and commercial vehicle applications. Understanding how the lubricant changes during extended drain operations is crucial in determining appropriate lubricants and drain intervals for these applications. A suitable aging screen test with an established relationship to field performance is essential. Over the years numerous methods have been studied (DKA, GFC, ISOT, ASTM L-60) with varying degrees of success1,2,3. Current methods tend to be overly severe in comparison to field experience, hence the need for further work in this area. As a result of recent work, a lubricant aging test method has been developed which shows good correlation with field experience, giving us an effective tool in the development of long drain oils.

Increasing requirements for comfort and lightweight design lead to higher acoustic target values for passenger car components, especially for automatic transmissions. The required increase of the acoustic tooth-mesh quality reduces the masking of tonal noises that are often the failure cause at the EOL test bench. Based on the mathematic transmission model that includes all orders and moments that are acoustically relevant, a database-based dynamic website supports the engineer with the localization of disturbing noises. After that, irregularities are extracted from the order spectra and are provided for the evaluation tool. A special search algorithm depicts all possible failure causes. On the one hand, refined entries allow the limitation of the solution sets; on the other hand, experience help to limit the solutions to acoustically relevant disturbance mechanisms.

In view of legal requirements and measures for climate protection, fuel efficient vehicles have become increasingly important. Against this background, transmissions are a key factor for two main reasons: Energy consumption and emissions can be reduced by optimization of conventional transmissions. The "ideal" transmission has a potential of contributing to this goal by about 10%. Between 4 and 5% out of this 10% can realistically be achieved. Driveline electrification constitutes another necessary step for CO₂ savings. To this end, an ideal option is integrating the electric components into the transmission. In view of the uncertain market development for hybrid car demand, a modular approach to electrification in transmissions is essential. This article outlines the electrification approach.

The worldwide increasing acceptance and success of modern automatic transmissions in passenger cars is based on innovative technology, driving comfort, shifting dynamic and - most important - fuel consumption reduction. New concepts are facing the challenge of further improvements in internal efficiency and very tough future goals on CO2 emissions in connection with more sophisticated gasoline and diesel engine technologies. Based on the competition and current diversity in automatic transmission concepts, high investments in production facilities must be taken also well into account when thinking about follow-up technologies of installed 8-speed and 9-speed technologies. This must also be considered for the different demands in regions and markets. So, how may a successful automatic transmission system look like in 2020 and beyond? Do we have even more gears than the current 8-speed and 9-speed? Does it make sense to increase the total gear ratio any further?

A new series of tractor transaxles (transmissions + rear axles) has been developed by ZF Friedrichshafen for the changed economic farming structures in the future. These transaxles feature market-demanded optimized functions combining powershift and electronic components for all 3 tractor main applications: working in the field on-road use loader work The development program criteria emphasized high economy for the user and excellent operating comfort. This paper gives an overview about the transaxle range structure and describes in detail the transmission concept, functions and features based on the transmission type T 7300. In addition, it provides information about the potential for upgrading.

In a collaborative investigation of ZF Friedrichshafen AG and the Fraunhofer-Institut für Betriebsfestigkeit LBF [1], both constant and variable amplitude fatigue tests were performed on induction-hardened automatic transmission shafts made from Ck 35 mod. steel. The objectives of the project were to evaluate the safety reserves of the shafts and to apply several selected methods to assess fatigue life, to compare these methods and to gain insights for future component developments.

Hydrodynamic launch elements, from the Foettinger principle of the torque converter to the first series production HCC wet clutch, are becoming more relied on in the transmission world for their high power density, launch comfort, and vibrational isolation capability. In order to attain the ambitious fuel economy objectives of the future, engine vibrations have to be successfully isolated from the driveline at low engine speed ranges without the use of the hydrodynamic circuit. This is now all the more challenging as new combustion engines are producing higher torsional vibrations as a result of fewer cylinders, higher combustion pressures, cylinder deactivation, and lower critical speeds. This paper will describe the next generation of powertrain vibrational isolation, dampening via powersplit. Additionally, a next generation wet launch element, the Hydrodynamically Cooled Clutch will be discussed.

Variable Damping systems for commercial vehicle applications have been in the market for several years now. The systems modify damping according to the actual demand within milliseconds. This reduces vertical accelerations which lead to improved comfort while maintaining vehicle stability and safety at the same time. Driver, cargo and vehicle are better protected. The technical effort for variable damping systems was in the past rather high and affected a limited market penetration. On the other side the used control algorithms did not tap the full potential of the system performance. New concepts, like integration of sensors or concentration on the most relevant axle, in combination with new control algorithms, simplifies the systems architecture and improves the performance. Besides the functional advantages, the system improves vehicle efficiency as it reduces the energy dissipated by the dampers. This energy would have to be generated by the engine.

Market trends clearly demonstrate the ongoing worldwide acceptance and success of modern automatic transmission solutions (AT, CVT, DCT) in both passenger cars and light trucks. This success is based on the further development of the driving comfort, shifting dynamics and - most important - the fuel consumption reduction modern automatic transmission systems offer. First, key driveline parameters such as overall spread and number of ratio's are to be discussed. The optimum spread for the fuel efficiency is in the range of about 8 to 9 and can typically be achieved by 8 to 10-speed transmissions. This is because modern gasoline or diesel-engines have a rather flat characteristic fuel map. Therefore the inner efficiency of the future transmissions becomes increasingly important.

Increasing dynamics and agility as well as simultaneously reducing fuel consumption and emissions - these are today's challenges in the field of driveline development. Now, hybrid technology is in the pipeline. ZF is developing hybrid components, modules, and transmissions, as well as complete hybrid systems. Among the key issues of hybrid technology discussion is also the topic of energy storage. In addition to the evolving trend focusing on hybrid technology, the market perceives a number of innovations with reference to automatic transmissions, dual clutch transmissions, and all-wheel drive systems. These technologies also enable a substantial reduction in fuel consumption as well as CO2 emissions. The networking of these new driveline and chassis systems allows for an optimized power management and enhanced driving dynamics with respect to stability and agility.