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 steering system performance, comparing different dampers and gears based on test results.
| Identifier | ExFiles\Box 95\1\ scan0350 | |
| Date | 23th September 1936 | |
| -4- Hs{Lord Ernest Hives - Chair}/FJH.{Fred J. Hardy - Chief Dev. Engineer}14/KM.23.9.36. Curve No.1 shows clearly that there is a condition of resonance in the steering system and that the greater the flexibility, the less are the joggles. This is completely borne out on the road. The limit to flexibility is set by the reduced directional control and the tendency to low speed wobble. The Ph.III is at present on this limit. The comparison of the la{L. A. Archer} Salle gear with the R.R. gear shows that there is no difference between them so far as reversibility is concerned and the good results obtained with the la{L. A. Archer} Salle on 30-EX were due to its flexibility and possibly the front dampers on this chassis. Curves Nos. 3 & 4 show some rather remarkable results from the tests on damping. The maximum governor pressure that occurs on the road is approx. 35 lbs/sq.in. Therefore from curve No.3 it can be said that so far as joggles are concerned we obtained no benefit from the dampers except for the amount of the initial setting. Our dampers give, theoretically, the same characteristic as a dry friction damper. In practice this cannot be so as, on curve No.4, dry friction dampers enormously reduce joggle whereas our hydraulic dampers have no effect at the same loads. The only explanation we can see for this is that while at low velocities of operation the hydraulic damper may give its desired characteristic, at high velocities, corresponding to wheel hop, the damping falls off and, we suspect, almost disappears. These results justify an investigation of damper characteristics under working conditions. The lines of the future development of the Ph.III steering system depend largely on the results obtained from Wraith wheel movement. It seems fairly certain that we must always keep clear of the resonant condition, although the reduced gyroscopic reaction will no doubt enable us to have a stiffer system than we can at present. | ||