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).
Brake linings, comparing Halo and Ferodo materials and their performance when hot.
| Identifier | ExFiles\Box 26\4\ Scan222 | |
| Date | 15th January 1924 | |
| R.B. 493A (40 H) (SL 42 12-7-23). J.H., D.{John DeLooze - Company Secretary} EXPERIMENTAL REPORT. Expl. No. 4388 REF: HS{Lord Ernest Hives - Chair}5/LG15.1.24. To R.{Sir Henry Royce} from Hs.{Lord Ernest Hives - Chair} c. to RG.{Mr Rowledge} CJ. c. to DA.{Bernard Day - Chassis Design} E.{Mr Elliott - Chief Engineer} c. to BY.{R.W. Bailey - Chief Engineer} BRAKES. BRAKE LININGS. With reference to the Halo material manufactured by the Scandanavia Belting Co., which we have been testing. We find that this material definitely overcomes squeaking brakes - it also is less liable to cut up the surfaces of the drum. There is however one serious disadvantage which we think should prevent us using it and that is - the co-efficient of friction is reduced very considerably when the brakes get hot. For instance, we made a test to see how quickly the car would pull up from 30 m.p.h. with the brakes cold - it took 86 ft. - with the brakes hot, it took 276 ft. We took this up with the makers and they agreed that the co-efficient reduces with the temperature, but they pointed out that other makers using this material have not complained. The co-efficient of friction of the Ferodo material increases with the temperature. We have not been able to notice the effect of this in the ordinary road wheel brakes, but in the case of the servo, we do find that it is more efficient when it is hot. The effect is that if we get equal braking when the brakes are cold, after the brakes have been used for a little while, we get most rear braking. H s. | ||