From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Page describing the operation and design of piston rings, focusing on oil control and the 'L' section ring.
| Identifier | ExFiles\Box 178\1\ img142 | |
| Date | 19th May 1926 | |
| - 9 - the ring grooves and shall "bed" evenly on the top and bottom spaces. If the rings have large clearance in the grooves the downward motion of the piston presses the ring against the top of the groove and changes the clearance behind and beneath with oil scraped from the walls. When the piston rises the ring then presses against the lower side of the groove and transfers the oil to the upper part of the ring where it is squeezed out on the return stroke, the cycle of operation being analogous to a pump. [Diagram Text] Left side: DIRECTION OF MOTION OF PISTON OIL SCRAPED FROM WALLS Right side: OIL CHANGES TO UPPER CLEARANCE Proof of this is afforded by an experiment in which some rings were employed which, although a perfectly good fit in the bore and exerted ample radial pressure, had approx. .025" clearance in the grooves. Under these conditions the engine would not run for long under reduced loads before oiling up the plug. A ring which we have employed with success, and known as the "L" section ring, relies for its oil scraping action upon the concentrated pressure given by its lower edge due to its sectional shape. The pressure over a transverse section of its face not contd. | ||