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).
Technical report discussing issues and remedies for brake squeak and petrol pump problems.
| Identifier | ExFiles\Box 121\1\ scan0297 | |
| Date | 24th June 1940 guessed | |
| -3- BRAKE SQUEAK. This is a problem on which opinions differ, a wide variety of remedies being successful under different conditions. Mr. A.{Mr Adams} F.{Mr Friese} Martindale's theory is that the lining should have a rising curve of against rubbing speed. This eliminates the "violin bow" effect, whereby with a falling characteristic, the shoe, on tending to follow the drum around, is pulled still further due to the increase of friction caused by the decrease of relative speed, and vice versa. These vibrations are of the order of 1/10,000", and disappear above a certain temperature (perhaps 100 deg. C). The kinetic friction between the two surfaces usually reaches a peak at about 0.9 ft/sec., and this is when the squeak is worst. At about 2 ft/sec. this kinetic frictional coefficient settles down to a steady value and squeak goes. This explains high frequency squeak, but there is a lower frequency noise due probably to insufficient rigidity of shoes, etc. or to excessive self-servo action; the latter form of noise has not troubled us. With regard to the linings, synthetic resin types are liable to squeak, while rubber does not; the latter smells when new or hot, and its μ is low, but it is consistent. Ferodo V.C.90 linings cause squeak easily, and in general a high lining will squeak and score the drum. V.C.90 has, however, been found suitable for servo linings, the wear being almost negligible, and not high enough to cause servo squeak. The best lining system is to fit Ferodo RU on the leading shoes and Ferodo RU on the trailing, the combination giving even wearing and only squeaking after serious over-heating. PETROL PUMPS. The S.U. electrical pumps are now very reliable and are all fitted on the frame below the driver's seat to avoid vaporisation which occurs in hot weather if the pump is fitted on the dash, and subjected to under-bonnet temperatures. There are now only two troubles: 1. If the pump is completely submerged in water for several minutes, water can get into the pump through the bakelite end caps, causing rust on the contact mechanism which is not so serious as when the water gets down the centre of the solenoid, and the rollers stick due to the rusty Continued. | ||