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).
Proposals to increase rear axle stiffness for Phantom III, Wraith, and Bentley models.
| Identifier | ExFiles\Box 92\5\ scan0100 | |
| Date | 19th December 1936 | |
| 302. Sg.{Arthur F. Sidgreaves - MD} and Hs.{Lord Ernest Hives - Chair} from E.{Mr Elliott - Chief Engineer} LESMITH C. Rm.{William Robotham - Chief Engineer} Ey. Da.{Bernard Day - Chassis Design} E.3/HP.19.12.36. Rear Axle Stiffness. Some time ago it occurred to me that rear axle shaft stiffness might be influencing clutch performance, but I was somewhat persuaded out of this by the comparative figures then available for other cars. We now know that it was the total transmission drive stiffness on which the comparison was based and not the stiffness of the final drive shaft. In connection with Phantom III we have now issued N.Sch.4982 on which we show scheme (1) for enlarging the axle shaft diameter to 1.4, which increases the stiffness 56% with an added weight of 5.6 lbs per car, and scheme (2) with a 1.5 diameter shaft which increases the stiffness 100% with an added weight of 9.6 lbs per car. Scheme (1) can be applied by merely boring out the existing differential casings a little larger, but scheme (2) requires some modified machining to the differential casings with however no alteration to the forgings. We are instructing scheme (2) to be made and tried, so as to try the 100% increased stiffness first. Scheme (2) could be brought in quickly if an when required by using 25/30 differential forgings and transfer the finished Phantom III parts to 25/30 production. If the 100% increased stiffness makes enough difference there might be some justification for trying scheme (1) which is more easily applicable to existing cars. With regard to the Wraith chassis, we have issued N.Sch.4979 which gives 100% increase on the axle shaft, and as these parces are not yet machined the alteration can take effect on the first chassis. With regard to the Bentley rear axle, we can increase the rigidity 50% right away at an increase in weight of 3½ lbs per chassis by modifying the differential casing in a way which may or may not affect the forging the rigidity can be increased 144% for an increased weight of 7.25 lbs per car. The drawings for the Bentley proposals are not yet completed. E.{Mr Elliott - Chief Engineer} | ||