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).
Crankpin length, lubrication improvements, and oil cooling recommendations for an engine.
| Identifier | ExFiles\Box 85\5\ scan0097 | |
| Date | 29th June 1935 | |
| -2- Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls}1/KW.29.6.35. When we suggest a crankpin length of 1.125" we are basing this on 20 hours endurance on a 1" pin on the standard 3½" bore engine. Failures on the 10,000 miles car only occurred on big ends that had inadequate lubrication at the very high oil temperatures. As pointed out in Hs{Lord Ernest Hives - Chair}/Smth.2/KW.1.6.35. this length compares favourably with the supercharged Kestrel. Obviously we should use the shortest crankpin possible from the point of view of crankshaft critical speed. We have experienced no ill effects from the small radii used on the existing narrow pin crank unit. For better lubrication we recommend two oil holes per journal and .100" wide grooves in the intermediate bearings. There is no doubt that with this crankshaft and the large bore engine, oil temperatures will be even higher than now. It would seem a good opportunity therefore to incorporate a SpectreCodename for Phantom III type cooler. Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls} | ||