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).
Test report on the safety of 30° cone angle Rudge Whitworth wheels for the Wraith model.
| Identifier | ExFiles\Box 10\4\ 04-page45 | |
| Date | 1st June 1938 | |
| To By.{R.W. Bailey - Chief Engineer} from Rm{William Robotham - Chief Engineer}/Gry.{Shadwell Grylls} c. Hs.{Lord Ernest Hives - Chair} c. Ds. c. Hdy.{William Hardy} c. Mx.{John H Maddocks - Chief Proving Officer} 658 Rm{William Robotham - Chief Engineer}/Gry.{Shadwell Grylls}4/WH.1.6.38. WRAITH WHEELS. As a further test on the safety of Rudge Whitworth wheels with the 30° cone angle we did the following experiment on 25.V.VI. The rear wheel nuts were removed on the road without jacking up the wheels and then screwed on one complete turn only. After about a mile the near side wheel had moved outwards and was in contact with the nut. The off side wheel had not moved. After about 6 miles the N.S. wheel was still against the nut and the nut had tightened 4 1/2 turns. On the off side, the wheel had still not shifted outwards in spite of several corners, but the nut had tightened 1 1/2 turns. This is because of epicyclic tightening due to the weight of the nut and can be demonstrated on a tyre fitter's rig. More violent braking of a hub than can be achieved on a car does not cause the nut to come off. These experiments were prompted in view of a customer skidding a P.III front wheel. Apart from a long continuous drive in reverse with very slack wheel nuts (which also applies to the existing Bentley) we consider the 30° wheels to be safe. We recommend their standardisation on B. series to overcome clonking on torque reversal. Rm{William Robotham - Chief Engineer}/Gry.{Shadwell Grylls} | ||