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 conducted on double shock dampers to resolve valve flutter issues.
| Identifier | WestWitteringFiles\W\May1931-August1931\ Scan004 | |
| Date | 13th May 1931 | |
| To R.{Sir Henry Royce} From Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} c. to Sg.{Arthur F. Sidgreaves - MD} Mor. c. to Da.{Bernard Day - Chassis Design} S. c. to Hy.{Tom Haldenby - Plant Engineer} Hy.{Tom Haldenby - Plant Engineer} ORIGINAL Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} 5/KT.13. 5. 31. X238; SHOCK DAMPERS. With reference to Dal/M6.5.31. We have been carrying out tests on the double damper to W. sch. 3190. Our efforts so far have been concentrated on getting the new type valve to work satisfactorily. The original difficulty with this valve was its tendency to flutter. This was indicated externally by a high pitched shriek from the valve and the indicating diagrams taken are shown in figures 1 and 2, sheet 1. These also demonstrate that we have not sufficient venting. Our first step was to try venting through the valve. A .025" hole through the valve from the high to the low pressure side gave the results shown in figures 3 and 4, sheet 1. It will be noticed that the venting was successful but the valve bounce persisted. Following this test we vented the high pressure side of the valve only to atmosphere, obtaining the diagrams shown in figures 5 and 6. From these it will be seen that though the valve bounce has been eliminated on the high pressure side, it still occurs to some extent on the low pressure side. Furthermore the vent is too big and the oil lost on the high pressure stroke produces lost movement at the beginning of the low pressure stroke. We then reduced this vent hole to that of the standard vent size on the present damper with the results shown on figures 7 and 8. In this the lost movement has disappeared but the valve flutter is coming up again. We thought that the flutter might be caused by some air still remaining in the system, we therefore increased the piston clearance, diagrams 9 and 10. The bounce is still present to a certain extent on the low pressure side and the lost movement due to too much oil escaping past the pistons is excessive. It will be noted that the loads on the damper for diagrams 1 to 10 are considerably higher than those at present used as standard, and we therefore reduced the valve spring to give us something approaching standard conditions, and repeated tests 3 and 4. It will be noted that under the lighter loads the conditions of flutter are much more severe. We cut down the clearance between the head of the valve | ||