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).
Analysis of engine bearing pressures with suggested improvements and general notes on a 4-cylinder engine.
| Identifier | ExFiles\Box 115\2\ scan0400 | |
| Date | 12th May 1939 | |
| - 3 - Due to explosion pressure only (600 lbs/sq."). Bearing pressure on outer inter. bearing F = 4200/2.5 = 1680 lbs/sq.". Due to all inertia + explosion pressure. Bearing pressure on outer inter. bearing F = 3315/2.5 = 1325 lbs/sq.". Suggested Improvements. Larger balance weights would reduce inertia load on centre bearing (its worst condition). They would also reduce the inertia load on bearing D, and the combined load on bearing D, which is very high. Moving the outer balance weights to the inner webs of cranks 1 and 4, as in my "Scheme b" for 6 cylinder engines of BY/B.8/G.29.12.38, would reduce the load on bearing D due to inertia and due to inertia + explosion when cranks 1 and 4 at B.D.C. Whether it would increase too much the inertia + explosion load on D when cranks 1 and 4 are at T.D.C. would require investigation, but I do not think it would. General notes. With a 4 cylinder engine torsional oscillation trouble is unlikely, so that there is no objection on this score to the fitting of large balance weights. Such weights would help to remove the bearing obstacle to high engine speeds and powers. The secondary unbalanced force at 3500 R.P.M. amounts to 1176 lbs. To deal with this will probably require vertically elastic engine mountings or a Lanchester vibrator. BY/B. G.S. Bower | ||