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 an axle failure on chassis 4-B-IV, linking it to brake jaggers and historical issues on other models.
| Identifier | ExFiles\Box 88\2\ scan0166 | |
| Date | 2nd March 1936 | |
| NOT SENT OUT SECRET x260 To Sg.{Arthur F. Sidgreaves - MD} & Wor.{Arthur Wormald - General Works Manager} c. to H.{Arthur M. Hanbury - Head Complaints} c. to By.{R.W. Bailey - Chief Engineer} c. to Ba. c. to Mx.{John H Maddocks - Chief Proving Officer} Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}10/KW.2.3.36. Axle Failure on 4-B-IV. We have been investigating the axle failure on 4-B-IV. Examination of the axle itself indicates that it has failed in torsion. In half a million experimental car miles, the only way we have managed to damage a Bentley axle in torsion has been by a front brake jagger. We have shown that a brake jagger can cause a load to be thrown upon the axle which is five times as great as the load obtained when the wheel is locked by braking in the ordinary way on dry concrete. Brake jaggers have been with us experimentally since the first day that we took a Rolls-Royce car on the roadfitted with front wheel brakes. A great many tests were carried out to find a solution to the problem and some of these are enumerated in Hs.{Lord Ernest Hives - Chair}1/LG.1.5.24. The cure applied on production was flexible drums and later, when these had to be discarded, axle control with the present type of ribbed drum. As far as we know, these cures have proved permanent in the hands of customers on the 20/25 and 40/50 HP. The Bentley, however, has not been entirely free from the disease in service, and additionally suffered widely from a subsidiary form at low speeds when water penetrated the brake drums. The low speed trouble has, as far as we know, been entirely eliminated by the water excluders standardised some six months ago. The actual cases of an axle being even twisted in a customer's hands are few and far between; we can trace two with obsolete parts which have since been replaced on all cars, and none with the latest water excluders and stiffened axles. | ||