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).
Test results on hydraulic dampers, focusing on pressure buildup from oil expansion.
| Identifier | WestWitteringFiles\S\June1928-August1928\ Scan069 | |
| Date | 9th July 1928 | |
| To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/An. c. to BJ: Wor.{Arthur Wormald - General Works Manager} c. to E: DA.{Bernard Day - Chassis Design} c. to BY: OY. ORIGINAL HYDRAULIC DAMPERS. +235 We have continued our tests on the RR. hydraulic dampers. In order to make the conditions of investigation better we have been using a 3.7" stroke and enlarged the diagram by gearing up the indicator drum and using a weaker indicator spring. This has enabled us to observe a number of features that were masked when we were using very high pressures and consequently small scale diagrams. We believe that we now have an explanation of the phenomena of the pressure remaining on the high pressure side during the low pressure stroke. When the damper is run up from cold, all the oil upon which work is being performed is virtually in a closed system consisting of both ends of the working chamber and the passage joining the high and low pressure ends. As soon as the damper starts running on our rig it heats up rapidly and the oil in this closed system expands. Possibly it is partially emul-sified and so its expansion is greater than that of neat oil. Now the only things that prevent the expansion building up pressure enormously are (1) The air vent. (2) Leakage past the working piston. Our tests have shewn that leakage past the working piston is very slight and so the air vent is really the only means of ensuring that the pressure due to expansion does not build up. contd .- | ||