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).
Experiments with hydraulic shock dampers, discussing the effects of oil temperature and viscosity on pressure.
| Identifier | WestWitteringFiles\R\2December1927-February1928\ Scan149 | |
| Date | 1st February 1928 | |
| To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/Rn.{Mr Robinson} c. to BJ. Wor.{Arthur Wormald - General Works Manager} c. to DA.{Bernard Day - Chassis Design} BY.{R.W. Bailey - Chief Engineer} c. to CY. ORIGINAL. Hs{Lord Ernest Hives - Chair}/Rml/LGS.2.28. HYDRAULIC SHOCK DAMPERS. X235 14-EX is running with shock dampers having restrictions as indicated in our Hs{Lord Ernest Hives - Chair}/Rml/LGl6.11.27. These produce an increased ball end loading for rapid axle movements. We have been conducting experiments to find the best way of eliminating temperature effects on dampers having a considerable velocity pressure factor. We have previously established that the shock damper runs at a temperature about 10°C above that of the atmosphere. Therefore if we assume that in normal places on the globe the atmosphere temp. may vary from -10°C to +40°C the temperature of the shock absorber oil will vary from 0°C to +50°C and this is the range over which we have worked. We find that if we take a damper and reduce the size of its ordinary passages until we get the pressure rise that we think is desirable, this pressure rise is affected too much by the temperature of the oil, or its viscosity, (graph 1.) over the range of velocities with which we are working. To get over the difficulty we do not have to alter the high pressure passage very much (graph.11) but the low pressure pressure passages very considerably. A possible explanation is that owing to the corners and bends in the high pressure passage the oil is in a greater state of turbulence, also on the high pressure side all the oil goes through a single passage. We do not suggest that the type of restriction we are using on the low pressure side is at all desirable. contd.. | ||