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 vehicle pitching and ride comfort in relation to damping, weight distribution, and seating position.
| Identifier | ExFiles\Box 16\7\ Scan334 | |
| Date | 26th November 1930 | |
| -2- that the most comfortable ride is at 30 to 35 M.P.H. Below and above this speed the discomfort increases. The peak indicated at 40 M.P.H. is due to pitching. These general features were prominent on tests carried out on several roads when looking for a suitable test stretch. Reduction in damping improves the ride at all speeds below 45 M.P.H. above this of course the car becomes very unstable without damping. It is noticeable that pitching peak at 40 M.P.H. is not improved by taking away the front damping, but that with no rear damping the pitching disappears. The curve obtained for the condition of no front damping falls off rather remarkably above 40 M.P.H. Actually under these conditions the front of the car pitches violently, the centre of pitch appears to be where the riding comfort measurement is recorded so that there is very little move-ment at this point due to the front pitching. The next tests (Fig.2) shews the effect of weight distribution. Need for reducing all weight over the front axle is clearly demonstrated by the increase in the pitching peak when extra weight is carried on the front, although at higher speeds it appears to be advantageous possibly due to the greater spring deflection due to the increased load. Weight at the rear improves pitching and high speed riding at the expense of extra discomfort at 30 to 25 M.P.H. Fig.3 demonstrates very clearly the enormous advantage to be gained by bodies such as 18-EX, 24-EX, and 26-EX., where the rear seats are placed well forward of the ~~front~~ [handwritten: rear] axle. The improvement registered is considerably more than anything we can do by alteration to weight distribution or shock damper loading. The large difference registered due solely to moving the seating position will possibly not be so marked on a car which is badly sprung in the first instance. 20-EX., the car under consideration is a well sprung car even when the seating position is immediately over the rear axle. The addition of weight representing a second spare wheel and luggage had the effect of increasing the spring deflection; normally of course this would be met by fitting stronger springs, so that actually the improvement probably would not be so marked as it first appears. The actual rear buffer clearances were reduced to N.S.R. 4.35" O.S.R. 4.1" by the addition of weight. | ||