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).
High-speed wobbles, comparing a Hispano car to the EAC and testing steering modifications on a Phantom car.
| Identifier | ExFiles\Box 29\1\ Scan044 | |
| Date | 14th September 1925 | |
| H.H. 493A (50 Hd{Mr Hayward/Mr Huddy}) (D.D. 31. 12-6-25) J.H.D. 4457 EXPERIMENTAL REPORT. Expl. No. REF Hs{Lord Ernest Hives - Chair}/RmL/LG14.9.25. To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} c. to CJ. BJ. c. to RG.{Mr Rowledge} E.{Mr Elliott - Chief Engineer} c. to DA.{Bernard Day - Chassis Design} BY.{R.W. Bailey - Chief Engineer} c. to Wor.{Arthur Wormald - General Works Manager} HIGH SPEED WOBBLES+ 4457 4214 We increased the strength of the springs of the Hispano car to their standard condition. We found that this reduced the tendency to wobble by about 25%. The Hispano car in its standard condition is definitely less susceptible to high speed wobbles than the EAC. The main reasons for this appear to be :- (a) Very harsh front springing. (b) Light front wheel brake parts. (c) Front shock absorbers capable of giving a very heavy friction load. (d) Front spring leaves approx. 17% wider than those of EAC, giving resistance to criss cross motion. In addition, possibly friction in the low geared steering promotes some damping and reduces the shocks which reach the driver from the wobbles. We are proving this by testing the effect of the new RR. steering on wobbles on the Phantom car. We have carried out further tests with varying pivot lean. We find that when we remove the self-centering from a car by leaning the pivots forward we much reduce the tendency of the car to wobble. We can still start a wobble but the latter cannot be sustained and built up to the same extent as when the pivots have a backward lean. There appears to be no advantage in going too far forward with the pivot lean, 5° giving as good results as 8° forward lean, the latter of course making the steering dis- contd :- | ||