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).
Audible knocks in 20 HP shock absorbers caused by a faulty non-return ball valve.
| Identifier | ExFiles\Box 55\4\ Scan279 | |
| Date | 3rd December 1928 | |
| To Hm{Capt. W. Hallam - Head Repairs}/WW. from Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer}1/LG3.12.28. Handwritten: X235, X4118 KNOCK IN 20 HP. SHOCK ABSORBERS. With reference to Hm{Capt. W. Hallam - Head Repairs}/WW9/W3.12.28. The only way we know of dealing with this complaint at the moment is to treat the matter in the same way as on Mr. Fillings car i.e., fit shock absorbers to the finest manufacturing limits. In the case of the two shock absorbers which you recently handed to us on which complaints had been made on a customers car, we find that in one case this was due to the non-return ball valve at the high pressure end not functioning properly. Apparently this valve had been tapped on to its seat, possibly more than once, and as received it was working in a cylinder instead of its ordinary seat. The result of this was that when operating quickly, there was a certain amount of lost movement in the shock absorber due to this valve sticking on its seat and this caused an audible knock. We do not know whether this is happening frequently, as it the first time we have traced the trouble to this source. We suggest however that whenever shock absorbers have audible knocks on the 20 HP. cars, this [strikethrough]fixxim[/strikethrough] feature should be examined. We have a number of other experiments which we wish to try out, but they have been held up for want of a car. We think we may get some information from Mr. Blackmores' car. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||