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).
Response to a memo about increased bore wear and oil consumption, discussing Aerolite Pistons and 'L' section rings.
| Identifier | ExFiles\Box 144\3\ scan0269 | |
| Date | 12th October 1937 | |
| Rm{William Robotham - Chief Engineer} 1220 Oil Consumption File. 12-10-37 We give below the answers to your memo Rm{William Robotham - Chief Engineer}3/AP 11-10-37 referring to Oil consumption & Cylinder Wear report. Ques ① We state as pointed verbally this morning that bore wear has been increased since the adoption of Aerolite Pistons, the possible reasons for this being (a) Increased compression ring pressure (b) Increased piston skirt clearance With regard to the "L" section ring, this has a theoretical flutter speed below 4000 rpm, and the reason why it controls oil on 25/30 may be due to one of the following:- ⓐ the vibration is damped out due to friction between the ring & groove ⓑ 25/30 is rarely driven at 4000 rpm or over, it is impossible on the majority of 25/30 cars to exceed 4000 rpm in top gear, this engine speed corresponding to 80 mph. We have not done much work with the "L" section ring on Bentley for the following reasons ⓐ G.W.H. has tried them on service complaints without success apparently with worn bores the ring as at present designed have too low a period to follow the sharp irregularities of cylinder contour generally evident in worn bores ⓑ the reduced width of ring coupled with its natural | ||