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).
Analysing the causes of wheel wobble and its relationship to toe-in/out and axle dynamics.
| Identifier | WestWitteringFiles\N\July1925-September1925\ Scan283 | |
| Date | 12th June 1925 | |
| R.R. 493A (50 H) (D.D. 31, 12-6-25) J.H.D. EXPERIMENTAL REPORT. Expl. No. REF:Hs{Lord Ernest Hives - Chair}/Ru2/LG1S.9.25 -3- (7) When the wheels are given an excess of toe in the wobbles become 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 factor are reduced to a minimum, shewed that this was clearly the case. 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 gyrostatic 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 frequency coincides with the frequency of the criss cross period of the axle. At this point, though still relatively impotent, the periodic impulses from contd . | ||