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).
The Wraith Rear Axle design, detailing gear ratios, stresses, and bearing modifications.
| Identifier | ExFiles\Box 7\3\ X 602 Axle Rear-page01 | |
| Date | 12th December 1934 | |
| Handwritten: Copy Rem 602 To Mr. EF. from Da.{Bernard Day - Chassis Design} Da.{Bernard Day - Chassis Design}2/HP.12.12.34. c.c. Mr. E.{Mr Elliott - Chief Engineer} Hs.{Lord Ernest Hives - Chair} Mdy. HLC. Wraith Rear Axle. Herewith is N. Sch.4278, rear axle centre casing and hypoid gears. The gears suggested are 7/32 = 4.575, approximately equivalent to the present 20/25 gear, and 7/34 = 4.860. The stresses in each case are rather lower on top gear than in the existing Bentley. The arc of contact is also rather greater. We should like the comments of the gear makers on these gears. We could have 8/37 and/or 8/39, but in these cases the stresses are rather higher than Bentley. We have increased the diameter of the driving shafts to 1.125 (larger than either Bentley or 20/25) and this necessitates increasing the R.H. roller bearing on the differential casing and modifying the casing at that end. We have also increased the pinion thrust bearing, giving larger balls, of the Ransome and Marles type, but have provided a combined Roller and Thrust bearing like SpectreCodename for Phantom III, should the all ball bearing prove inadequate. The increased thrust bearing enables us to obtain a larger cone for the universal joint flange. In other respects the axle follows Bentley. We are stressing out the tubes, and shall send you information about these shortly. We have shown a method of closing in the slot for machining the bridge facing which we suggest could be applied to the Bentley axle casing in the case of a new casting. N.Sch.4278 herewith. Da.{Bernard Day - Chassis Design} | ||