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 system components, including the pivot axis and lever joints, in relation to reducing friction and shimmy.
| Identifier | ExFiles\Box 29\1\ Scan112 | |
| Date | 8th October 1925 guessed | |
| contd :- -15- selectiveness of the steering. Having regard to this end they have changed different variables according to the types of car in question but which all have for their object the reduction of the friction in the pivot axis, in the steering joints and in the steering box. (a) Pivot axis. The steering of the 12-HP. Renault which is worm and sector is supported by roller bearings. It has been proved that if one replaces these by plain bearings, shimmy is much reduced. It disappears completely if one reduces the spring flexibility and judiciously adjusts the position of the ball of the steering arm. In doing this we increase the friction in the steering to the detriment of lightness. We have measured this reduction - it is about 15 to 20% with balloon tyres at 21.4 lbs/sq.in. (b) Joints of the lever. (Cross steering tube and side steering tube). On the 12-HP Renault and on most cars these joints are ball joints with automatic compensation for wear by springs. We have tried altering the rating of these springs without obtaining any useful results. We have even removed the springs and replaced them by solid india-rubber which has had the effect of increasing the violence of the road shocks upon the steering wheel without suppressing wobbles. (c) Reduction. There is a tendency to steering reduction on modern cars (see table 1.) as well as to increase the precession of the steering by altering either levers, or the parts enclosed in the steering box. When one increases the length of the steering pendulum lever, shimmy has a tendency to increase. contd :- | ||