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).
Investigation into a 'wheel driver knock' issue on the 4 1/4-litre Bentley, focusing on splining and wear problems.
| Identifier | ExFiles\Box 84\4\ scan0120 | |
| Date | 13th November 1936 | |
| To Rm{William Robotham - Chief Engineer} X 202 K/W. KC to Hs{Lord Ernest Hives - Chair}/GWH.{George W. Hancock - Head Chateauroux} K/KC/DPB/13.11.36. WHEEL DRIVERS. PIECE No.G.100050. As there seems a tendency for wheel driver knock on the 4 1/4-litre Bentley to become epidemic, I give below data enabling you to take this matter up with W. You will notice that so far this quarter, which is approximately about half way through, that out of 18 cases of wheel driver knock there are no less than 11 in the 4 1/4-litre class, none of which are over 9000 miles and only two of which can be said to be owned by owners who are hard but good drivers. It has occurred to me that retrospective action will have to be taken with these drivers dogs should the trouble become epidemic. I have therefore taken the liberty of making a sketch which will increase the load area of the splines of the driver dogs by approximately 60%. The following points have come to my notice when dealing with this assembly:- (1) The splining of the hub piece No.GB.519, 520 (female splining) is rough finished. (2) The edges of the splines have not been radiused. (3) The greater part of the wear takes place on the female splines and not on the male. With regard to (1 & 2). It seems to me that the design of the splined flange at the end of the spline is the cause of making the splining difficult in that it is not possible to put a finishing broach through for cleaning up the radii of the splines. If this flange was removed and a steel washer substituted, a better job could be made by the use of the finishing broach. I think it is possible that it is the lack of this radius that causes the impression that the dog is a tight fit, whereas in practice it is this radius hammering away under load which starts the dog off on its initial slackness. -contd- | ||