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).
Comparative road tests focusing on steering, suspension, and handling characteristics.
| Identifier | ExFiles\Box 17\4\ Scan013 | |
| Date | 31th August 1931 | |
| Hs{Lord Ernest Hives - Chair}/lid{A. J. Lidsey}3/AI31.8.31 contd. -2- The route chosen for the comparative tests was a straight road on which it was possible to maintain a speed of 50 M.P.H. over the majority of a twelve mile stretch. All the results given are the average of six runs over this test road - three runs being made in each direction at 50 M.P.H. In order that the snatchmeter figures obtained should be as correct as possible, it was necessary to hold the steering wheel as freely as was possible, only checking it lightly when steering was necessary. During all the tests a flexible shackle was fitted to the o/s front spring. This shackle had been tried a long time previously but owing to the springs in it at that time being considerably too weak, very little investigation was carried out and it was put on one side. The shackle was similar in operation to the W.M. shackle, suitable springs were fitted and in addition it was altered so that it could quickly be made solid. The results obtained with this device are very promising - joggles and shocks are damped out very considerably and with the addition of between 2 and 4 lbs friction in the steering column (measured at the rim of the steering wheel and obtained by using a steering column friction device similar to that used on P.I. experimentally some time ago) the steering wheel becomes quite steady. The springs used in the flexible shackle produced a spring rating of approximately 5300 lbs/in, measured at the spring eye, [text struck through] the load at the spring eye to produce .125" movement being 650 lbs, and to produce .250" movement 1320 lbs. These were the strongest springs which it was possible to use in the shackle. Dealing with the results obtained on these tests :- Front Tyre pressures. Joggles are very much worse with low tyre pressures, the higher the pressure the less pronounced the joggling. Wider Track. 1" wider track wheels are slightly worse than the standard wheels giving 58.5" track. Flexible Shackle. The effect of the flexible shackle does not show up to its full value unless the results obtained by using column damping in conjunction with it are taken into account. This is because the wheel is allowed to move (being held very loosely) and the effort moving it when joggling takes place is so slight that a small amount of friction in the column is sufficient | ||