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 a hydraulic damper, detailing the performance of staggered orifices and issues with oil frothing.
| Identifier | WestWitteringFiles\S\June1928-August1928\ Scan040 | |
| Date | 1st June 1928 guessed | |
| contd :- -2- under all circumstances. The indicator therefore confirms our impressions that the action of the RR. hydraulic damper is very consistent under all conditions unless some obstruction gets under one of the valves. This is not a frequent occurrence, however. We made a second series of tests to find out how the staggered orifices behave under temperature variation. The result was not quite what we expected as at high temperatures and extreme axle movements a certain amount of frothing seems to take place in the staggered passages, and it is difficult in our experimental arrangement, to get rid of the air bubbles so formed, the air vent being the other end of the passage. It will be seen that we improved matters somewhat by making a way of escape for these bubbles, but so far have not eliminated the trouble. We have tried various oils, both mineral and otherwise, but they all give the same result. However the phenomenon only occurs for 11" axle movement, a very exceptional case which possibly is never encountered, and the trouble should be easily overcome by suitable design. The tests are sufficient to shew that staggered passages do, for all conditions under which we are likely to work, eliminate the effect of oil viscosity and yet give xxxxxxxxxxx any required pressure velocity rise. It should be remembered that in these diagrams the valve load is only 55/60 lbs. as against the standard 65/80, all the remaining pressure rise is due to the restrictions, and therefore absence of temp. effect | ||