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 damper, link, and bearing knocking noises and potential solutions.
| Identifier | WestWitteringFiles\T\2January1929-June1929\ Scan038 | |
| Date | 19th January 1929 guessed | |
| contd :- -3- When we reduced the side play, the noise from the links was less emphatic but still clearly detectable. We tried slotted and drilled high pressure valves as used in America to cushion the reversal of load. These only effected a 20% improvement. Once a customer has complained about these damper knocks, the noise becomes an obsession with him and he can afterwards pick out the slightest sound from this source. We should like to distinguish between 'link' knocks and 'bearing' knocks that we have previously reported on. The knocks from a slack lever bearing is louder than a link knock but more like the noise of a mallet striking the frame. It can usually only be heard over potholes or anything causing large axle movements. It is not so continuous (except in very badly worn bearings) occurring only once every ten yds. or so on a moderately bad road. Usually an 80% cure can be effected by the slotted or drilled high pressure valve. We have arranged an elaborate rig for tracing shock damper noises, but the results are most disappointing. We cannot even confirm road results. Body amplification appears to be the crux of the matter. Summarising the position: Bearing knocks are now uncommon - we have appreciated the necessity of good fitting bearings for some time and since then only isolated cases of complaint have occurred. Link knocks are hardly an epidemic but we have a number of complaints. Practically speaking, the trouble is mainly confined to contd :- | ||