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).
Change in rear axle design for the Wraith from a Scott tube to a welded banjo type.
| Identifier | ExFiles\Box 114\1\ scan0050 | |
| Date | 5th October 1936 | |
| X.015 Aircraft welded frame To Ss.{S. Smith} and-Wer. from E.{Mr Elliott - Chief Engineer} c. Hs.{Lord Ernest Hives - Chair} By.{R.W. Bailey - Chief Engineer} Do. Hdy.{William Hardy} Rear Axle Construction. With regard to memos Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}14/KW.24.9.36 and Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls}15/KW.24.9.36, it will be remembered that the original decision made at an early conference was to proceed with a banjo type of rear axle design for Wraith, which has been duly carried out. This design was based on using a Scott tube formed in one piece, and the Design department initiated experiments to be carried out in parallel, to test the strength of the size of Scott tube to be employed, with particular reference to meeting the condition where the axle is jacked up at a single point in the centre. The results of these experiments were disappointing and showed that the Scott tube, even with a stiffener added, was not good enough for the job. It was, therefore, necessary to change over to a welded type of banjo in which better material could be used. The welded banjo makes a more expensive job, but the costs are still such as to be well below those of our present construction, and there is practically no change required in the scheme as designed. In changing over to the welded banjo we have in fact made a simpler job of the ends of the axle tubes by forming the extensions and spring saddles in one piece, and calling for machining on the ends of the banjo tubes on the outside only. In our experience when axles have suffered damage the bending takes place on the small diameter extensions carrying the wheel bearings, and in our scheme these are in the present material, namely, nickel steel. The larger diameter portion of the axle casing which by virtue of its greater rigidity is more immune from damage, can permissibly | ||