Large bore diesel engine piston ring and cylinder liner design was ratcheted up more than a few notches on the efficiency scale by research that flowed from the (now concluded) European Union sponsored HERCULES project. The piston ring itself might seem a fairly inconsequential part of the whole engine, yet commercially important length of Time Between Overhauls (TBO)  is largely determined by piston running behaviour and its effects on the wear of piston rings and cylinder liners. Recognising this fact, one sector of the interrelated study was devoted to an investigation into how engine friction might be reduced, but first it may be helpful to reprise HERCULES.The HERCULES Project The project title word HERCULES is itself an acronym (at a far stretch) signifying ‘High Efficiency R&D on Combustion with Ultra-low Emissions for Ships’, which pithily defines the scope of the three-and-a-half year project led by MAN Diesel SE and Wärtsilä Corporation with a t... [More]