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).
Tests, noise issues, and potential production problems with various shock damper valve designs.
| Identifier | ExFiles\Box 105\3\ scan0253 | |
| Date | 8th July 1932 | |
| Copy X5820 To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/Rn.{Mr Robinson} c. Sg.{Arthur F. Sidgreaves - MD} Wor.{Arthur Wormald - General Works Manager} c. E.{Mr Elliott - Chief Engineer} Da.{Bernard Day - Chassis Design} C. Bv. Hdy.{William Hardy}(W.W.) Hs{Lord Ernest Hives - Chair}/Rn.{Mr Robinson}8/AD. 8.7.32. J.III SHOCK DAMPERS N.Sch.3405/9. We have had a set of dampers to N.sch.3405/9 running silently on a chassis. They are fitted with a valve to Hs.{Lord Ernest Hives - Chair}657/A.{Mr Adams} We have not yet managed to silence the valve using the external oil pressure. Attached is a summary of the recent tests we have made. It will be noticed that Hs.{Lord Ernest Hives - Chair}657 valve has a definite effect on the ratio of the high to the low pressure load, also that the low pressure diagrams definitely suffer at the high frequency small amplitude movements. This might cause impaired road holding at speed. We believe that eventually we may get this double valve to operate silently under all conditions of load, oil temperature and velocity, but so far it has shown itself to be exceedingly capricious. We should like to recapitulate our experience with shock absorber noises. At present we are carrying a legacy of about 300 hydraulic shock absorber complaints per quarter. These are complaints on types of damper that had completed 10,000 miles without noise being detected, yet on some customers cars they have persistent-ly given trouble. With the double valve, we have a potential noise producer that can be worse than anything we have previous-ly tested. On the other hand withour existing F.test production shock absorbers with cast iron valve seats and the split piston we have not so far recorded a single complaintthough we agree they have only been off produc-tion test about six months. For this reason we are anxious to avoid getting into production on the new double valve in a hurry and so repeating our previous disastrous experience. We are concerned that the automatically adjustable shock damper scheme to N.Sch.3468 so far relies on this valve. A point in connection with the damper to N.sch. 3405/9 is that with the slotted drilled and masked valve as we have it at present, we shall require a filter, as any one of the slots or holes choking will cause the valve to become noisy again. | ||