Which of the following functions are performed by the piston rings in a multi-cylinder tractor diesel engine?
Options:
(A) Sealing the combustion chamber to prevent blow-by of high-pressure gases into the crankcase
(B) Transferring heat from the hot piston crown to the cylinder liner walls
(C) Scraping excess lubricating oil from the cylinder wall back to the oil sump
(D) Supporting the entire lateral thrust force directly at the crankshaft main journal
Answer Key:
A, B, C
Step-by-Step Solution & Explanation
Piston rings have three primary functions:
- Gas sealing (compression rings prevent combustion gas leakage).
- Heat transfer (conveying up to $70\%$ of piston crown heat to the cooled cylinder liner).
- Oil control (oil scraper ring regulates oil film thickness and scrapes excess oil back to sump).
Lateral thrust force is supported by the piston skirt against the cylinder wall, not by piston rings at the main journal.