Nitrided Piston Ring Pack for Diesel Engines

Engine developments have led to higher mechanical and thermal loads on the components, at the same time that lower friction losses are also sought. Therefore, the development of better materials and of surface treatments has received great emphasis.

This paper presents the results of dynamometric engine tests with a proposed piston ring pack, composed of a gas nitrided steel top ring, a nitrided gray cast iron second ring and a normal production chrome plated oil ring. The proposed pack showed very low wear when applied to a medium duty diesel engine, besides being a cost-effective alternative to the conventional pack with moly coated and chrome plated (respectively in the top and second) rings.

The proposed pack also caused very low wear on the cylinder bore, specially near the TDC, where the bore wear is usually maximum.