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).
Comparing the stiffness of Bentley front brake drums to solve juddering issues.
| Identifier | ExFiles\Box 84\2\ scan0102 | |
| Date | 22th February 1934 | |
| GRX x206 To Ex from Da.{Bernard Day - Chassis Design} c. Hs{Lord Ernest Hives - Chair}/Grylls. Bentley Front Brake Drums. Comparing stiffness by moments of inertia, the stiffness of the existing C.I. ribbed drum is .00564. The 20/25 steel brake drums before the days of axle control, were reduced in thickness by trial until juddering was eliminated. The thickness arrived at was .125, the stiffness of which, allowing for the different material, is .000650, so that the Bentley drums are approximately nine times as stiff as the maximum found possible to eliminate juddering. To reduce the C.I. drums to the same stiffness as the 20/25 steel ones, the former should be .160 thick. But the axle control should almost certainly allow a considerable additional stiffness to be carried. If the ribs were turned down by stages, the following stiffnesses would result:- Height of rib above drum. Stiffness. Stiffness compared with:- Existing Bentley. steel 20/25. .275 (as now). .00564 1 9 .150 .002595 .46 4 .100 .001947 .29 3 .050 .001426 .253 2.2 .0 .00128 .227 2 It appears that it will have to be determined experimentally, by the experiments we understand are now going on, exactly how stiff the drums can be to obviate juddering. Da.{Bernard Day - Chassis Design} | ||