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).
Comparing the propeller shaft designs of the Wraith, Bentley, and Phantom III models.
Identifier | ExFiles\Box 148\4\ scan0051 | |
Date | 17th December 1936 | |
12 6 & B2 from HPS.{Horace Percy Smith - Experimental Factory Mgr} c. to Rm.{William Robotham - Chief Engineer} GRY{Shadwell Grylls} HPS.{Horace Percy Smith - Experimental Factory Mgr}1/CB.17.12.36. PROPELLER SHAFTS. On comparing drawings of the Wraith and Bentley details with those of the latest Phantom III shaft, N.Sch.4928, it is rather surprising to find only fractional differences exist between essential dimensions of the two sets of parts. To consider a few examples, there is for instance only .125 difference in propeller shaft diameters, the trunnion needle roller bearing diameters vary by only .030, the waist and spline diameters on the trunnion are identical and the length of splines could be the same, and in fact, if it were not for a difference of .300 on the pitching of the trunnion bearings and a corresponding variation in the coupling bolt centres, the essential features would be virtually interchangeable. Dies for the Wraith details are, unfortunately, now well in hand, but even at this stage, in view of the slight differences which distinguish one assembly from the other, would it not be advisable to give serious consideration to the possibility of effecting a compromise between the two designs which would neither add a lot of weight on Wraith nor unduly weaken the Phantom III shaft whilst making essential features common to Bentley, Wraith and Phantom III. It would appear that the length of propeller shaft tube is the only essentially variable factor, but we should be glad to receive your comments. HPS.{Horace Percy Smith - Experimental Factory Mgr} | ||