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).
Spring stiffness tests and their effect on vehicle ride characteristics.
| Identifier | ExFiles\Box 43\2\ Scan183 | |
| Date | 10th November 1926 | |
| Oy13-E-111026 -4- November 10, 1926 (11) Effect of wide axle pad. We inspected the springs off the l.h. drive Phantom referred to, with a heavy clip representing the wide axle pad on the new type front axle. We found that clipping the springs increased the stiffness 14%. (This agrees with the calculated stiffening effect when the plates between the U bolts are considered inactive.) On other springs this stiffening effect is as low as 8%. It appears to vary with the flatness of the short leaf. Also it is necessary to get negative camber on the spring when tightening it to get the maximum stiffening effect. (12) This gave us a total spring stiffness of 32-1/2% of the normal load. We made a new pair of front springs in which the stiffness when clipped to the axle was 30% of the normal load. This is the lower limit of your recommendation of some months ago. The improvement in riding of the car with the new springs was very noticeable. The indications are that the rear passengers are extremely susceptible to small changes in the front spring stiffness. (13) If you would care for us to send you full details of the investigation of the two cars referred to above, we should be very pleased to do so. We wish to suggest that similar investigations on the 20 hp. might be very useful. Yours very truly, Maurice Olley A sketch print is attached showing the positions of C.G.s on the two cars and the various positions of the center of oscillations in pitching on the Phantom for various arrangements of the weight and springing. The center of oscillation is just below the front seat for all conditions except the extreme of 500 lbs. on the back. M.O. MO/E | ||