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).
Cost, design, and testing of the Wraith rear axle.
| Identifier | ExFiles\Box 7\3\ X 602 Axle Rear-page15 | |
| Date | 14th August 1936 | |
| X144 602 HS{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} c. De. He/Gry.{Shadwell Grylls} E/HDV E.3/HP.14.8.36. Wraith Rear Axle. ------------------ With reference to the question of the Wraith rear axle, I have seen G/Rb{R. Bowen}, and he has told me that there is a definitely useful saving in cost with the Wraith scheme due to the simplification of the central bevel gear unit. We also know that the cost of the banjo itself is no more than that of one of our taper tubes of the normal design. Then again the setting of the bevel gears can be done directly in the housing without using a rig, and without the chance of introducing an error in transferring from the rig to the axle. This should be both a convenience and a saving. A point where we have come unstuck somewhat on this axle is the low elastic value of the material of the banjo compared with its ultimate strength using the Scott tube. It is somewhat unfortunate that the conditions of the test on the Scott tube were not quite representative of what occurs in practice, and we think in making the second test with the stiffening plate added to the centre of the banjo that the correct conditions might be obtained by using a bolt for carrying the load through the centre of the banjo to the jacking plate. It would help us considerably if you could undertake a jacking test on the Packard rear axle. We are looking into the question of using a welded banjo as we think this would give us definitely stiffer material, and this is the type of thing that is in general use on American chassis. We are also investigating the Kirkstall Forge scheme but personally I have not great hopes of this. From the conversation I had with G/Rb{R. Bowen} it appears that we have got a definite economy in the Wraith axle as | ||