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 steering behavior and axle torsion when a single front brake is applied.
| Identifier | ExFiles\Box 30\6\ Scan200 | |
| Date | 12th June 1925 | |
| H.R. 493a (50 H) (D.D. 31. 12-6-25) J.H.D. EXPERIMENTAL REPORT. -3- Expl. No. REF Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer}/LG7.9.25. It is therefore necessary to assign some other reason for the steering taking charge when one front brake only is applied, and this reason must be definitely connected with the torsional movement of the axle on the springs when the brake is applied. We believe that the explanation is as follows. When one front brake only is applied on an axle which is not fitted with some form of torque arm, the pivot on the side being braked is given considerably greater forward twist than that on the opposite side. On the majority of cars, unless exceptionally strong springs are fitted, locking one front wheel only will cause the pivot on that side to actually assume a forward lean, while the other is about vertical. In this position the steering is in unstable equilibrium for while the vertical pivot neither raises or lowers the car when turned, the one leaning forward when turned towards the side being braked, lowers the chassis. Conversely the weight of the chassis is always tending to turn this pivot and steering the car to the side in question. This is sufficient to start a dive which, since the normal castoring action of the steering has been removed, tends to get more severe as the lock increases. In any case we believe that preventing the twisting of the front axle under braking torque is the most powerful factor, apart from centre point steering, in promoting safe brake application under poor conditions of equalisation. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||