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).
Technical analysis of high speed wheel wobble, its sustaining factors, and causes.
| Identifier | ExFiles\Box 178\1\ img116 | |
| Date | 13th July 1926 guessed | |
| - 17 - That is, the lower the wobble frequency, the greater the amplitude of wheel flap. If at 40 m.p.h. the wheels turn through 14°, when a wobble occurs at 60 m.p.h. they may only turn through 8°. In other words, the lower the wobble speed, the greater the discomfort for the driver. The actual factor which sustains a high speed wobble is the grip between the tyre and the road. We have proved this by making the car wobble on rotating cast-iron drums. If we reduced the co-efficient of friction between the tyre and drum by pouring water on the latter, the wobble instantly vanished. Another interesting fact is that wobble cannot take place unless the wheels are connected by means of the cross steering tube i.e., one wheel cannot wobble alone. Still another fact which we ascertained is that a wobble cannot be sustained without a side steering tube. It is to this fact that hydraulic steering probably owes its success as a wobble eliminator. (b) Causes of high speed wobble. As we have previously shewn, these may be sub-divided into two portions. (1) Those which make the speed or frequency of the wobbles come within the range of the car speed. (2) Those which aggravate the wobble and sustain it when condition (1) has been fulfilled. Of primary importance under section (1) are front wheel brakes and balloon tyres. Any tendency to add weight to the ends of the car axle, lowers the road speed at which it can wobble. comtd. | ||