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).
Proposal for a semi-floating rear axle design for the Bentley 50, discussing advantages and construction options.
| Identifier | ExFiles\Box 111\4\ scan0004 | |
| Date | 25th October 1937 | |
| File By.{R.W. Bailey - Chief Engineer} from Rm{William Robotham - Chief Engineer}/Gry.{Shadwell Grylls} 1044 c. Hs.{Lord Ernest Hives - Chair} c. Da.{Bernard Day - Chassis Design} c. Hdy.{William Hardy} Rm{William Robotham - Chief Engineer}/Gry.{Shadwell Grylls}2/AP.25.10.37. 802 BENTLEY 50 REAR AXLE. Only Rolls-Royce and Alvis now use a fully floating axle. The advantages of changing to a semi-floating design are price, weight and freedom from wheel driver knocks. The latter would be greatly appreciated by R.R. customers and remove from the perpetual free-of-charge list a formidable complaint. Both the price and weight reductions depend on the use of pressed wheels. Two rear hubs weighing 13 lbs. and costing £b. vanish. Although the half shafts will weigh 7 lbs. more between them and the wheel weight be unaltered we shall be lighter on the deal. The inevitably stiffer half shafts in a semi-floating design are not entirely wasted weight as they also benefit clutch jaggers. In view of these advantages it is proposed to try a semi-floating rear axle on this car. We have, therefore, gone into the possible arrangements that can be used. As there is no intention of departing from the present type of Rolls-Royce centre construction, various methods of location of the half shaft are precluded. On many American cars a horse shoe washer at the inside end of the half shaft locates the shaft in an outward direction. In order to fit or remove this washer, the pressed steel cover of the banjo axle is first removed. The first limitation, therefore, in the Bentley 50. axle is that the outward location of the half shaft must be taken at the wheel bearing. The biggest decision is whether to fix the hub on a taper, or bolt it to an upset end of the half shaft. If wire wheels are to be used on an upset end, the bearing overhang will be at least 2". Now that Sales have asked for an abandonment of wire wheels the over-hang can be reduced to under ½". What is there to be said for the taper construction? The greatest advantage is in the Service Station as the removal of a brake drum only necessitates un-doing one nut. Secondly, the outward thrust is taken by a shoulder on the shaft, replacement of the wheel bearing being an easy matter. Against the taper is the knowledge of failures that continued | ||