Development of a Nitrided Ring Pack for Medium and Heavy-duty Diesel Engines

Recent developments of diesel engines have aimed the improvement of their durability as well as cost optimizations. Although these tendencies seem to be contradictory, many technologies have been applied with results that are very satisfactory. The development of components, specially the piston rings, has led to solutions with optimized performance of service life as well as of functional characteristics of oil consumption control, blow-by control and friction reduction.

The use of nitrided piston ring packs allows the maximization of the system performance without compromising the cylinder bore wear, as the tribological pair is very compatible.

This paper presents the results of tests with nitrided first and second groove rings for medium and heavy-duty diesel engines. The wear results of the rings and the cylinder bore and their functional behavior are analyzed, showing that the nitrided steel ring in the first groove and the nitrided cast iron ring in the second groove are viable alternatives to replace the conventional ring packs (with moly and chrome coated rings) in these engines.