Many leading automotive manufacturers are focusing R&D efforts on transmission developments to exact greater fuel efficiency, while maintaining overall vehicle performance. Achieving this balance of engine and transmission function combination could improve vehicle market appeal as it would slow down the sacrifices, such as handling, acceleration and extra features, consumers may otherwise have to make when opting for greater fuel efficiency. This is leading to OEM investment in six, seven, and eight-speed, continuously variable (CVT), dual-clutch, auto shift manual and select shift manual, adaptive control and electronically-controlled transmission technologies. Ford is planning to introduce automatic six-speed transmissions on more than half of its North American vehicle range through 2009.
Although often overlooked, transmission fluids need to be developed in-line with these technological developments and changes in production for the performance potential of the different transmissions to be fully realised. Use of a fluid that has not been specifically developed for a higher performance transmission means it is unlikely that intended efficiency benefits can be achieved and can lead to component damage, resulting in costly transmission repairs or corrective repairs under warranty agreements.
Use of a fluid that has not been specifically developed for a higher performance transmission means it is unlikely that intended fuel efficiency benefits can be achieved and can lead to the need for an exchange transmission.
New Rules:
It is increasingly important for fluid suppliers to work with OEMs and components suppliers to truly understand the operational demands of new clutch designs and develop high performance fluids. Fluid requirements vary across the range of transmissions and there is no single fluid that can effectively perform in manual, dual, automatic and continuously variable transmissions. Each of the transmission types require different levels of lubricant viscosity depending on the speed they operate at, the level of metal-to-metal contact and the design of the gears and clutch plates. All of these factors affect the level of friction generated during operation, which needs to be accurately controlled to optimize torque and fuel efficiency.
The demands placed on fluids will intensify as OEMs aim to extend oil replacement intervals and use smaller volumes of oil in transmissions.
However, although there is no ‘one-size-fits-all’ lubricant solution, there are similarities between the operational demands of the different transmissions. The demands placed on fluids will intensify as OEMs aim to extend oil replacement intervals and use smaller volumes of oil in transmissions. Furthermore, the transmissions will generally operate at higher speeds and temperatures, exerting further pressure on fluid performance. These factors can lead to high levels of oil stress, reducing lubricant viscosity and oil life and compromising fluid performance and friction control, increasing the potential risk of accelerated component wear and poor transmission performance and power output leading to a transmission failure.
The use of different materials in automatic transmissions, such as plastics and elastomers in seals could present further challenges. These new materials are designed to maximize component durability and improve environmental compliance and transmission fluids need to be developed to maintain seal compatibility to avoid potential leaks and loss of pressure.
The reality is that new automotive transmission technologies are playing an increasingly instrumental role in improving passenger car fuel efficiency. Developing and using specifically designed synthetic high performance fluids will help OEMs to cost-effectively experience the performance potential and true life span of the new transmission technologies and meet market demands for fuel efficient and low-carbon foot print vehicles.
