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).
Explaining the phenomenon of cylinder over-oiling related to the orientation of chamfered piston rings.
| Identifier | ExFiles\Box 72\1\ scan0002 | |
| Date | 27th February 1925 | |
| R.R. 493A (50H) (D.B. 175 25-9-24) J.H.D. EXPERIMENTAL REPORT. Expl. No. REF. Hs{Lord Ernest Hives - Chair}/ACL/LG27.2.25. RE. CYLINDER OVEROILING - E.A.C. Observation of the different results obtained with the standard rings when used in the usual way with the chamfer downwards and when inverted, prove the results are much better when the ring is in its usual position and the following theory is offered to explain the phenomenon. The ring being chamfered i.e. having a narrower section at that part, and the radial pressure of the ring against the cylinder wall being caused by the bending of the ring, it follows that the distribution of pressure over a section of the ring in the direction of piston travel, will not be uniform, but be of greater intensity nearest the chamfered edge. This means that when travelling upwards - the lighter loaded part leading - the ring will ride up over the oil film and function in a similar manner to the Michell Pad thrust brgs. On the reverse stroke however, it will not have the advantage of the wedge shaped oil film and will tend to shear the film and act as a true scraper. [Diagram text:] P Sectn. of ring Wedge shaped oil film. Distribution. This action can clearly be demonstrated by pushing a flat piece of metal over a lubricated face plate and concentrating the load on one edge. Hs{Lord Ernest Hives - Chair}/ACL. | ||