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 soft levers, connecting links, and roll rod designs for various car models.
| Identifier | ExFiles\Box 151\2\ scan0299 | |
| Date | 5th October 1936 | |
| -2- Hs {Lord Ernest Hives - Chair} /Les.5/KW.5.10.36. The following designs show soft levers pressed on to the soft knurled shafts - 1. 25 HP. Front Roll Rod, N.Sch.4803. 2. Ph.III " " N.Sch.4763. 3. Ph.III Rear " LeC.4995. 4. Wraith II Front " N.Sch.4850. 5. Wraith II Rear " LeC.5133. Connecting Links. The use of rubber as bearings for a roll rod and its connecting links has the disadvantage of resisting the necessary movements and thus increasing the effective spring rating. On a 25 HP. car a front roll rod to Ex.20877 was fitted, together with 5½" initial deflection springs. It was found that the comfort gained was only slightly better than 4" initial deflection springs and no roll rod. With the roll rod disconnected, the comfort was much improved. Fig.I shows load deflection curves for the front of this car. The figures are only taken from normal position to rebound. The front of the car was raised on a crane whilst the wheels were on a weigh-bridge. The difference in the curves is due to the torsional stiffness of the silent-bloc bushes. Tyre and spring rate without the roll rod is 270 lbs/sq.in. and with the roll rod 305 lbs/sq.in. Graph G.360711 shows the torsional stiffness of various silent-bloc bushes. The bush we had chosen for the 25 HP. EX front roll rod is the worst bush for torsional stiffness. This is owing to its large internal diameter. The Bentley EX front roll rod which is fitted with the more flexible silent-bloc bushes is reported to be responsible for harsh riding on C-B-IV in France. On this car, which has 3½" initial deflection front springs instead of 2½", it appears to be doubtful whether the advantages gained from controllability compensate for the increase in harshness of the ride. | ||