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 brake squeak complaints, comparing liner materials and damping devices on Phantom I and II cars.
| Identifier | ExFiles\Box 47\3\ Scan016 | |
| Date | 24th January 1931 | |
| -3- Material of Liners (c). The most noticeable feature in connection with the quarterly list of complaints of brake squeaks is the fact that there are approximately double the number of complaints on Phantom II. cars as compared with Phantom I cars. This does not confirm the opinion that the light design of front axle is responsible for the trouble, since the Phantom II. axle is to all intents and purposes precisely the same as used for the past three years [handwritten amendment: the last 2 years] on Phantom I. cars. Our tests so far have convinced us that Ferodo brake lining is superior to Ferobestos both from the point of view of braking efficiency and squeaks. Ferobestos liners have been fitted to a very large percentage of Phantom II. front axles and this in our opinion explains the discrepancy between the Phantom I and II quarterly complaints. Damping of Brake Drum (d). We have investigated the possibilities of all the usual brake drum damping devices. These devices are very inconsistent in their effects, in some cases a seemingly complete cure being effected, and in others little or no improvement can be noticed. In no instance however have we been able to effect more than a temporary cure. These devices seem to depend for their action more on distortion of the drum than actual damping of vibrations and they confirm the importance correct bedding of the liners. General. To sum up our investigations, we can say that we are almost certain of effecting a cure by fitting new Ferodo liners and bedding the liners as already described. This may not be a permanent cure in every case, but generally speaking repeated complaints after this treatment are rare, and in any case the car has to cover a fairly big mileage before the brake again becomes a potential squeaker. When this does happen it is due to a concentric bedding having been produced on the liners due to wear. This fact suggests that there would be a reasonable prospect of getting a permanent cure by providing some form of eccentric pivot which shifted the effective pivot inwards as the shoes are expanded, thus keeping the bedding at the toe end of the liners as the brake wears. CONT'D.{John DeLooze - Company Secretary} | ||