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).
Investigating the causes and characteristics of wheel wobble using a dynamometer.
| Identifier | ExFiles\Box 29\1\ Scan045 | |
| Date | 14th September 1925 | |
| R.R. 493a (50 H) (D.D. 31, 12-6-25) J.H.D. -2- EXPERIMENTAL REPORT. Expl. No. REF Hs{Lord Ernest Hives - Chair}/Rml/LG14.9.25. tinctly objectionable. We have not tried this test on a second car yet; it appears to us so far that this gives an explanation of part of the feeding of the wobble. We have driven the front wheels of a car on dynamometer drums at speeds equivalent to road speeds up to 55 m.p.h. At first [struck-through: we] could get no wobbles with balanced balloon tyres. By lifting a small portion of the weight off the front axle when running, however, we were able to bring wobbles up. A small tackle was used attached to the frame, we do not know yet exactly what lift we exerated. The wobbles were exactly similar in amplitude and frequency to those we have experienced on the road. The drums were perfectly smooth. We still found, by means of the Chronograph, that the period of the wobbles when they started, were exactly the same as those of a wheel revolution, with a tendency to keep in step with the wheel as far as possible. As the natural criss cross period of the axle is the main factor, however, in dictating the frequency of a wobble, when the road wheels slow down the wobble period does not quite follow then. When too far out of step, the wobble stops. We hope w to be able to observe a wobble in slow motion with the oscilloscope on this rig up, and also get the axle suspended in the air at wobbling speed. We consider the reason why the car did not wobble easily with the full load on the tyre was [struck-through text] possibly due to the convex nature of the latter creating resistance to twisting. We are investigating this. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||