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).
Indicator diagrams and tests on American shock absorbers.
| Identifier | ExFiles\Box 28\1\ Scan131 | |
| Date | 18th July 1928 | |
| To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} c. to BJ. Nor. c. to E.{Mr Elliott - Chief Engineer} DA.{Bernard Day - Chassis Design} c. to BY.{R.W. Bailey - Chief Engineer} OY. 4832 Hs{Lord Ernest Hives - Chair}/RmL/LG18.7.28. AMERICAN SHOCK ABSORBERS. X235 We have taken indicator diagrams of the American shock absorbers. We used a high pressure valve modified as indicated in OY1/R6.12.28, with two slots giving a leak of .003 sq.ins. as America found that this gave the best riding. As will be seen from the attached results, at the speeds which we use in our tests the leak does not produce any reduction on the maximum pressures and only delays the valve opening appreciably on the 3.7" strokes. We made two series of tests - one to shew the effect of slotted leaks on a standard damper, and the other to compare the actual leaks with higher loads as used by the Americans with our English damper. Until we can measure the actual behaviour of the axle on the road, we do not know at what speeds to run the dampers with leaks. On the standard damper it does not matter so much because below a certain velocity the characteristic of the damper remains unaltered, with leaks however, the characteristic alters down to zero velocity. We additionally tried the front damper with a leak of .0015" but this leak was so small that it did not make an appreciable difference on our tests. We will try out these dampers on the road but feel that we shall always be up against contd :- | ||