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).
Letter to Ferodo Ltd. discussing brake lining testing methods and a resulting front axle failure.
| Identifier | ExFiles\Box 141\1\ scan0228 | |
| Date | 4th January 1937 | |
| 1180 (Experimental Dept.) Rm{William Robotham - Chief Engineer}/AFM{Anthony F. Martindale}14/R.{Sir Henry Royce} 4th January, 1937. J.N. Longley, Esq., Chief Chemist, Ferodo Ltd., Chapel-en-le-Frith. Dear Mr. Longley, Thank you for your letter of the 29th December. The order for the various materials we want will be sent to your Sales Department from our Order Office. I note you say that you find it necessary to run linings continuously for two hours at fairly high temperatures before a stable condition is reached. May I point out that this never happens on a car ? We think our method of testing resembles more closely road conditions than yours, the bedding of the Ferodo pieces is excellent and we nearly wear them out in a test. This variation in coefficient of friction is a fact no manufacturer of brake linings will admit, but it has involved us recently in a most disastrous series of experiences, culminating in the failure of a front axle at high speed. While we immediately took steps to counterbalance fierceness mechanically, we think it unfortunate that your testing never exposes these traits in your linings, as unless it does we cannot expect any help from you. I hope you will forgive me for saying this, but I want to make clear that our troubles are no myths. I will certainly test V.G.90 on our rig to test its accuracy. I will prepare the graphs you ask for and send prints to you, or, if you prefer,, I could bring them over and discuss them. Yours truly, | ||