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 memorandum discussing the causes and remedies for high-speed steering wobbles on the 40/50 HP model.
| Identifier | ExFiles\Box 28\4\ Scan240 | |
| Date | 22th May 1925 | |
| X457. WOT. C. Hs.{Lord Ernest Hives - Chair} BY15/H.{Arthur M. Hanbury - Head Complaints} 22.5.25. HIGH SPEED STEERING WOBBLES - 40/50 HP. ------------------------------------ Referring to Br1/H.20.5.25. I did not realise that we were having difficulties from high speed steering wobbles with standard tyres. We did of course put a definite prohibition on the use of balloon tyres on the front axle knowing that they were likely to give trouble when used in conjunction with the front wheel brake equipment. One is inclined to think that the wobble referred to is more a question of out-of-balance in regard to the wheel or tyre, particularly the latter, than to high speed wobble one encountered with balloon tyres. The only remedies one knows of at the moment are to definitely balance both wheels and tyres, and if it should happen that the tyre is out of balance, this is a matter which should be brought to the attention of the Dunlop Company, as whilst we can balance a wheel, a tyre is always likely to be changed and the combination of a tyre and wheel therefore must not be balanced as it stands. The foregoing should deal with one phase of the matter. If the wobble is related to the high speed balloon tyre wobble, it can unquestionably be modified by the increasing of the pressures in the front tyres. One would recommend an increase of 25% as being a likely amount to assist matters. At the same time, before applying this, the actual tyre pressure under which the tyre has been tested with the wobble should be checked carefully with a gauge, to make sure that the pressure is not below standard. Addition of friction on the pivots as arranged by Br would be effective against an out-of-balance wobble, but not very much use against the high speed wobble, as the friction couple is not of sufficient dimensions to cope with the balloon tyre combined bounce and wobble, for which we discarded the tyres in question. BY.{R.W. Bailey - Chief Engineer} | ||