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).
Analysis of damper performance, steering characteristics, material considerations for casings, and a summary of findings.
| Identifier | WestWitteringFiles\V\December1930-February1931\ Scan086 | |
| Date | 3rd January 1931 guessed | |
| - 3 - (2) There is a greater pressure velocity increase on these dampers than on any other R.R. damper we have tested. As an example, in Fig.(2) Sheet 2, the static pressure required to give a bell pin load of 80 lbs. is 160 lbs/sq.in. whereas the maximum dynamic pressure recorded on the diagram is 231 lbs/sq.in. We are trying to find out exactly what portion of the passages causes this pressure.velocity increase. (3) Drilled valves actually increase the efficiency of the damper, as we have previously ascertained, for movements of small amplitude, whilst decreasing the maximum pressures slightly. STEERING. We consider that the characteristics of the front hydraulic dampers indicated in these diagrams, together with the spring in the levers and shafts are partially responsible for the complaints of steering joggles that have been made on P.II. One reason we say this is because everyone is agreed that the Continental Touring Cars, which have Hartfords fitted, are free from joggles and road shocks. As we have previously stated, we believe that undamped movement of the front axle is fatal from the steering point of view. We have already managed to alter the characteristic of the front damper so that the area of the L.P. stroke for small movements is only 30% less than that of the H.P. stroke and are continuing our investigations with a view to improving the steering on existing cars. CAST IRON DAMPER CASINGS. It will be noted that the dampers in France have suffered from pieces of metal under the valves. We think that this indicates the desirability of trying cast iron cases, as these particular dampers were fitted up with the greatest care and the trouble must be due to scoring between the piston and cylinder. We are carrying our further experiments to determine whether the expansion of the shock absorber casing has anything to do with the loss of efficiency over small movements. The latest 'Delco' dampers we have obtained have cast iron cases. SUMMARY. We can save a few bits by deleting the non-return ball for the air vent. We can make the front dampers more efficient. We cannot condemn valves drilled with .032 holes. We confirm that the links are the worst feature for noise on existing dampers. We believe that the double piston damper designed by West WitteringHenry Royce's home town is the right type for silence and efficiency, though the Americans are reverting to the single piston horizontal type on the score of economical production. contd. | ||