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).
Failure of Phantom III rear brake drums and proposing a design modification.
| Identifier | ExFiles\Box 92\4\ scan0109 | |
| Date | 11th November 1935 | |
| To E.{Mr Elliott - Chief Engineer} 230b Hs{Lord Ernest Hives - Chair}/AFM.{Anthony F. Martindale}20/KW.11.11.35. Phantom III Rear Brake Drums. We appreciate your argument about the stress range in the thin drum edge. The depth of section here is only .550" as against .725" at the first rib. We agree entirely that stones or grit must be the final reason for failure. The Ph.III drum bends nearly 3 times as much as a Ph.II drum under a toggle load of 500 lbs. Apart from the fact that we think this probably spoils the bedding to some extent, and wastes at least 1/2" of pedal movement, we have been apprehensive that this bending might even fatigue the cast-iron. There is a suggestion in G.W.H's memo. that the drum as a whole is liable to crack, and so we are glad you agree to an increased rib depth. A thickening of the external drum edge would probably solve the problem entirely. Hs{Lord Ernest Hives - Chair}/A.F.Martindale. | ||