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).
Report page detailing tests on vehicle wobbles, focusing on the effects of tyre pressure, tyre type, and chassis weight.
Identifier | ExFiles\Box 28\4\ Scan206 | |
Date | 2nd January 1923 guessed | |
contd:- -3- We found that the tyre pressure has a considerable effect upon the degree and the speed at which the wobbles take place. We have never yet been able to produce wobbles if we run on bare rims without tyres and yet correct the pivots to ensure that the amount of backward lean remains the same as with the tyres on. Our tests prove clearly that with the same pressures the cord tyre produces worse wobbles than the fabric tyre. If cord tyres are pumped up to 120 lbs. per sq. inch, the wobbles are practically gone. There are slight signs from 3 to 6 m.p.h., but above that, none can be felt. With everything on the car remaining in the same condition except that we lower the tyre pressure to 50 lbs., wobbles then start at 4 m.p.h. and continue up to 20 m.p.h. and are 5-times as violent. If we reduce the tyre pressure to 20 lbs. pressure, the wobbles then are only very slight. It is unfortunate that the pressures at which we usually run are the worst for bringing up the wobbles. We carried out a test by taking a chassis which was bad for wobbles. We first of all proved that we could obtain wobbles equally as well if the car was towed as if driven under its own power. We then removed the engine entirely making sure to correct the pivots. We found with this weight removed that it was practically impossible to build up any wobbles. If the steering was flicked, there was a sense of wobble but it could not be built up into a period. We then fixed a top half crank case and bolted on to the under-side of the crankcase a 250 lbs. weight. It was still not possible to build up wobbles, but if contd:- | ||