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).
Oil consumption test results for split skirt pistons with various piston ring arrangements.
| Identifier | ExFiles\Box 132\4\ scan0097 | |
| Date | 19th October 1937 | |
| Rm{William Robotham - Chief Engineer}/the.3/W.19.10.37. FIG. II of filling a radius on the upper edge of all rings as well as lower edge is not shown since we only took one reading, this being exactly the same as the previous result, with the radius on the lower edges only. Fig.III shows results obtained with standard ring arrangement and with 4 ring pistons having stops and no stops. Curves (5) and (7) again show how the consumption increases from the initial figure when using stops to prevent rotation of rings in grooves. With the standard arrangement the initial consumption is not as good as the stopped piston but it gradually improves as shown by curves (1) and (2). Curve (3) shows the effect of blanking up the extra oil hole in the connecting rod. In this connection it should be mentioned that these curves are again taken on the test bed under full throttle conditions. The curve shows, however, that with good bedding rings not fluttering, the use of the oil hole does not upset consumption. The initial point on curve (3) was taken exactly 2 hours after the final point on curve (2), by continuing curve (2) it will be seen that the consumption would have been virtually the same had the hole been left open. With rings having a tendency to flutter it is quite conceivable that under 'over-run' conditions as experienced on the road the effect of the hole would be quite marked. Service reports by G.S.R. show that blanking up the hole does definitely improve [Graph Data] Title: 25/30 OIL CONSUMPTION TESTS. R.R. SPLIT SKIRT PISTONS. MOTORINE 'C' OIL. PRESS. 26 LB/[]" OIL VISCOSITY:- 70 SECS. REDWOOD No.1 SCALE AT 100 °C. " 28,000 " " O °C. Y-Axis Label: OIL CONSUMPTION (PTS/HR) X-Axis Label: HRS RUN CURVE LEGEND: ① STD. RINGS WITH 'L' SECTION 2ND COMP. RING. HOLES IN SCRAPER RING GROOVE BLANKED ② As ① BUT WITH RM.{William Robotham - Chief Engineer} 201 'L' SECTION SCRAPER RING ③ SCRAPER RINGS AS USED IN ① REPLACED. ④ AS ③ BUT WITH RADIUS FILED ON LOWER EDGE OF ALL RINGS. | ||