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).
Analysis of axle shaft and bearing design, comparing stresses with American manufacturers.
| Identifier | ExFiles\Box 111\4\ scan0010 | |
| Date | 16th December 1937 | |
| - 2 - projected has an overhang of 0.8". Increasing this to 1.5" reduces the stress under condition (3) slightly, without appreciably increasing the stresses under conditions (1) and (2) and makes a cheaper and more orderly design. Increasing the overhang to 3.15" for a 1.575" dia. shaft increases the stress under condition (1) to that in the Cadillac shaft and decreases the stress under condition (3), but is not so low as the Cadillac figure. Increasing the overhang to 3.76" for a 1.625" shaft makes the stress under condition (1) equal to that in the Cadillac and reduces the stress under condition (3) to less than the Cadillac stress. These large overhangs, even if desirable, could not easily be accommodated in the design. To utilise the next standard size bearing the shaft would be increased to 1.750" dia., which with 1.5" overhang would give a stress under condition (3) which is 5% more than the corresponding Cadillac stress and stresses under conditions (1) and (2) which are below the respective Cadillac figures. It would appear from figures given with Rm{William Robotham - Chief Engineer}/Gry.{Shadwell Grylls}R/AP.25.10.37. that Cadillac stresses are in excess of those used by other American manufacturers, as Oldsmobile on a lighter car use a shaft of the same diameter as Cadillac and the Packard 120, a lighter car than the Oldsmobile, has a shaft only very slightly smaller. As a comparison with our standard fully floating axle tubes, Table 3 gives stresses under condition (3) in the proposed axle shafts and the Bentley 11 and Wraith 11 axle tubes. The stresses in the present standard tubes are considerably less than those in the shafts. It is suggested that a 1.750" shaft with 1.5" overhang be used. The 45 M/m (1.772") x 100 m/m.{Mr Moon / Mr Moore} (3.937") bearing requires no larger housing than the 1.625" x 4.00" and therefore involves no additional weight at this point. Increasing the diameter of shaft from 1.625" to 1.772" increases the diameter of the outer end of the axle tube, the total increase of weight of tubes and shafts being approximately 4 lbs. DA{Bernard Day - Chassis Design}/HB.{C. E. Harcombe} | ||