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).
Complaints of knocking rear shock absorbers on the 20 HP model and a proposed solution.
| Identifier | ExFiles\Box 55\4\ Scan268 | |
| Date | 1st November 1928 | |
| To BY.{R.W. Bailey - Chief Engineer} from Hs{Lord Ernest Hives - Chair}/Rn.{Mr Robinson} c. to DA.{Bernard Day - Chassis Design} c. to Wor.{Arthur Wormald - General Works Manager} c. to Hm.{Capt. W. Hallam - Head Repairs} c. to Mr. Brock. X235 Hs{Lord Ernest Hives - Chair}/RmB/LG5.11.28. SHOCK ABSORBERS. X5520 X235 We have had complaints from Sales that the 20 HP. rear shock absorbers knock on their trials car. Simultaneously several customers have complained. We have tried their cars and the shock absorbers are certainly audible. The 20 HP. rear damper is identical in design and dimensions with the 40/50 dampers. The latter give no trouble. The only point where the 20 HP. rear damper differs from the others is in the mounting. We therefore feel that the mounting amplifies the noise in this case. We have proved that the hydraulic dampers cannot knock if they are made to sufficiently fine limits. A pair of 20 HP. rear dampers selectively assembled by production to be a 100% job proved to be perfectly silent on Mr. Pillings car on which three or four ordinary sets had previously been turned down. We do not suggest that this is a solution to the trouble, but until we have experimentally evolved a cure it would appear to be desirable to give the 20 HP. rear dampers particular attention when assembling. Also a careful examination of those on test for the noise complained of. The fine limits on the hydraulics are absolutely essential in order to maintain silence in service, contd :- | ||