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).
Design and construction of the proposed Wraith rear axle.
| Identifier | ExFiles\Box 7\3\ X 602 Axle Rear-page11 | |
| Date | 11th August 1936 | |
| X1044 602 To R.{Sir Henry Royce} From Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls} c. to Wor.{Arthur Wormald - General Works Manager} c. to Da.{Bernard Day - Chassis Design} c. to By.{R.W. Bailey - Chief Engineer} c. to Hdy.{William Hardy} Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls}7/EJ.11.8.36. REAR AXLE CONSTRUCTION. The design of the proposed Wraith rear axle is of banjo construction using a Scott tube. The object of this departure from the usual R.R. practice, is to reduce cost, and facilitate assembly of the gears. The sample Scott tubes supplied by the manufacturers have already proved by static deflection tests that they will take a large permanent set if the car is jacked up under the centre of the axle. A Phantom 111 axle loaded to 4000 lbs. does not take a set. Whereas we are obviously in favour of any arrangement that renders fitting of the parts easier we do not consider this so important as the elimination of backlash. The banjo arrangement suggested for Wraith has no fewer places in which slack can exist, than the present axle. We recommend therefore trying a half floating axle but reverting to the usual R.R. arrangement of axle tubes, somewhat as shown on the attached sketch. This scheme has no splines on the half shafts eliminating therefore two slacks on each side of the car. Furthermore wear cannot develop behind the half shaft bevel as the thrust is now taken on the wheel bearings. We realise that adjustment of mesh of this bevel gear will not be easy but think it can be done by first offering up the axle tube and measuring the gap between it and the centre box and then fitting washers to suit behind the wheel thrust bearing. In addition to eliminating the wheel drivers from the point of view of slack there will be a decrease in factory cost of 16/- per car at present required for machining the necessary splines. Removal of the rear brake drums would not be the difficult job it is at present if we adopted a half floating axle. Hs{Lord Ernest Hives - Chair}/M.Grylls. | ||