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).
Development and analysis of the EAC.7 steering geometry, comparing it with Phantom and India models.
| Identifier | WestWitteringFiles\Q\April1927-June1927\ 1 | |
| Date | 1st April 1927 | |
| TO HS.{Lord Ernest Hives - Chair} FROM DA.{Bernard Day - Chassis Design} ORIGINAL DA{Bernard Day - Chassis Design}3/M1.4.27. c to B.H. EAC.7. STEERING GEOMETRY. X7430 (crossed out) X5430 We are working on an arrangement of the EAC.7. steering which will combine the two previous proposals with a view to getting the geometry as perfect as possible. In the meanwhile there are one or two points about steering geometry in general which we should like some further information upon if possible. If we take the Phantom geometry which you like, we find that it gives nearly perfect geometry on the rebound, and poor on the bump. The existing EAC.7. on the other hand is good on the bump and poor on the rebound, and these two features are just about inverted in the two steerings. It would appear from this that the rebound is more important than the bump, and that our previous efforts to make the bump as good as possible were wrong. We wonder if you could confirm this, for instance, could you take a Phantom and put on temporarily a long pendulum lever so as to invert the present geometry, that is, make the bump as perfect as possible, and spoil the rebound? If this then had the same characteristics as the original EAC. 7. it would look like confirmation of the impression we have now. With reference to the India geometry we see that that is bad in both directions. The original 20HP. was also bad in both directions, but there was a small place in the middle where it was comparatively good. To illustrate our meaning we enclose prints of diagrams of the geometry of Phantom,/EAC. 7. From this it will be seen that the EAC.7. geometry as actually fitted up is considerably worse than we originally intended, due to slight modifications which occurred afterwards, including the base pin on the axle lever. DA.{Bernard Day - Chassis Design} | ||