CATNU1201

piston Rings anD cylinDeR lineRs
CUTTING CARBON, CUTTING EMISSIONS
The piston is part of a system that wouldn’t work effectively
without equal innovation in the technology used in related
components, particularly the piston rings. These must
provide an exceptional seal, they must be resistant to high
temperatures, high pressures and very high forces while
minimising friction and wear. They must last longer than ever
before despite working with less lubrication. Even the fuels,
traditionally an important source of lubrication especially
in diesel engines, are becoming less lubricious as sulphur
contents are reduced. That’s why Federal-Mogul employs
more than 200 scientists, engineers and technicians dedicated
to the development and testing of piston rings.
The properties required of the base ring material and of the
surface layer can be substantially different, so an effective
technique is to optimise each individually. For piston rings,
Federal-Mogul has developed a number of unique materials
and coating options that both reduce friction and improve
durability.
Chrome Ceramic coatings (CKS ® ) were specially developed
for diesel engines and are noted particularly for their
increased durability. Other benefi ts are low wear of the coating
and cylinder wall and avoidance of scuffi ng. This innovation
provided the starting point for the development of the Goetze
Diamond Coating ® (GDC ® ), which ensures exceptionally
good anchoring of the embedded hard particles to provide an
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even harder surface. The wear characteristics of GDC ® are
four times better than those of conventional hard chromium
coatings and two times better than those of chrome ceramic
coatings, making it ideal for the next generation of downsized,
very high specifi c output diesels and allowing service intervals
to be further increased.
Improvements can also be made by optimising the shape of
the oil ring. Federal-Mogul’s 2011 PACE Award-winning
Goetze ® LKZ-Ring ® is an innovative two-piece design
originally developed for highly-demanding diesel
applications and now also optimised for directinjection
petrol engines. Compared with the best
conventional two-piece rings, the Federal-Mogul
design reduces oil consumption by up to 50 percent
and friction by up to 15 percent. The rings utilise a new,
stepped design on the ring lands, which provide less resistance
when the piston is on the compression stroke, reducing
pumping losses. When the piston is on the power stroke, the
pressure more effectively returns the oil that lubricates the
cylinder to the oil pan. As this prevents the oil from entering
the combustion chamber, it cannot create carbon on the
spark plug or cylinder head. So as well as helping to keep
oil consumption consistently low, the LKZ-Ring ® also helps
ensure that combustion quality is not reduced by the products
of burnt oil.