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).
Technical memorandum detailing issues and testing of the propeller shaft for the Wraith model.
| Identifier | ExFiles\Box 9\2\ 02-page21 | |
| Date | 17th November 1938 | |
| 687 To By.{R.W. Bailey - Chief Engineer} from Rm{William Robotham - Chief Engineer}/Gry.{Shadwell Grylls} c. Sg.{Arthur F. Sidgreaves - MD} c. Hs.{Lord Ernest Hives - Chair} c. Ds. c. RHC.{R. H. Coverley - Production Engineer} c. Hdy.{William Hardy} Rm{William Robotham - Chief Engineer}/Gry.{Shadwell Grylls}1/WH.17.11.38. PROPELLOR SHAFT - WRAITH. Accumulated experience on a number of cars indicates that the propeller shaft on existing Wraiths is not entirely satisfactory. We originally decided on the "1300" type Hardy Spicer shaft for Wraith because it had satisfactorily done two 15,000 mile tests on Bentleys and saved some £b. The Wraith testing in France showed up no troubles. The first trouble in England occurred on 27.G.VI being run by Mx.{John H Maddocks - Chief Proving Officer} when the rear joint ran dry. We took this up with Spicers and found the star piece was an early type containing little lubricant and liable to this trouble. A new type star was already on their production lines and fitted to every production Wraith shaft supplied to us. Such a shaft was fitted to Mx{John H Maddocks - Chief Proving Officer}'s car. 17,000 miles later it had run out of lubricant. At about the same time a propeller shaft vibration appeared on 25.G.VI, and examination showed that the needles had dug into the races. Further investigation then showed the following history of trouble. Type of Joint. 27.G.VI 1300 Early star rear joint dry...........10,000miles. 27.G.VI 1300 New " one joint dry, both indented................17,000 " 25.G.VI 1300 Early " both ends indented, front worse than back...........10,000 " 24.G.VI 1300 " " both ends indented...........14,000 " EXR.1 1300 New " both ends just marked all lubricant gone........13,000 " but (32-lx.) 1350 New star very good...............17,000 " (37-lx.) | ||