A fundamental research program to provide a basis for those technology advancements should
include investigations into the following subjects:
Pitting-fatigue effects related to lubricant chemistry.
Alternative lubrication approaches.
Diesel Engine Manufacturers
When designing new engines, the diesel engine manufacturers are driven by the following needs:
Better fuel economy.
Higher power output.
Faced with severe reductions in allowable emissions by 2002, and even more drastic reductions
in subsequent years, the diesel engine manufacturers are now almost totally consumed with
lowering emissions. Although specific details of how the emission requirements will be met are
kept proprietary by each manufacturer, it is generally agreed that three of the most likely
approaches include exhaust gas recirculation (EGR), higher injection pressures, and exhaust
aftertreatment. However, these approaches also result in decreased fuel efficiency. Depending
upon the specific approaches taken, methods to reduce emissions probably will cause a 5 to 10%
decrease in fuel efficiency by 2007. This provides further incentive to offset this decrease by
methods such as reducing friction.
Each of the potential methods for reducing emissions also raises new concerns about friction and
It is clear that all of the engine manufacturers are giving serious consideration to EGR, but this
technology raises two serious concerns: soot loading of the oil, which is expected to increase the
wear rate of engine parts; and higher oil acidity, which is expected to cause corrosion of rings,
bores, and valves. In the long term, both of those deterioration mechanisms could decrease the
engine emission performance and increase maintenance costs. Therefore, there is a strong need
for better materials, coatings, and surface conditioning technologies to protect the engine
components, and for new lubricant formulations that are compatible with the higher level of
Higher injection pressures not only place higher stresses on certain engine components, but they
also require much closer dimensional tolerances, which makes lubrication more critical but also
more difficult. Improved materials and low-friction, wear-resistant coatings will be needed.