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).
Wheel wobble, its causes related to toe-in/out, and axle behaviour.
| Identifier | ExFiles\Box 29\1\ Scan066 | |
| Date | 18th September 1925 | |
| R.R. 493x (50 H) (D.D. 91, 12-6-25) J.H.D. EXPERIMENTAL REPORT. -3- Expl. No. REF Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer}2/LG18. 9. 25. (7) When the wheels are given an excess of toe in the wobbles becomes worse - when a toe out, they tend to disappear. (a) Tests on the road gave an indication that this was the case. (b) Tests on the drums, where masking external factors are reduced to a minimum, shewed that this was clearly the cas.e A bad wobble with 1" toe in vanished when the wheels were set parallel. (8) If the wheels could not turn, the reaction of the ground would be eliminated, and there would be no high speed wobble. Back axles never high speed wobble or tramp. They tend to move parallel. Their criss cross period in many cases is lower than some front axles. Their wheels are just as likely to be out of balance as those of a front axle. Admittedly, owing to the wheels being unable to turn, their gyrosatic couple would oppose a criss cross vibration. We do not believe that this is the main preventative; we believe they do not tramp because the wheels being unable to turn can get no reaction from the ground. Our mental picture of a wobble from start to finish is therefore as follows :- A small tyre inequality or out of balance gives the axle a very small criss cross movement. The axle is not at all responsive to these criss cross impulses until, as the road speed increases, their frenquency coincides with the frequency of the criss cross period of the axle. At this point, though still relatively impotent, the periodic impulses from contd :- | ||