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, testing the effects of different springs, axle inertia, and front-end weight.
| Identifier | ExFiles\Box 28\4\ Scan282 | |
| Date | 1st August 1925 | |
| R.R. 493a (50 M) (O.D. 31. 12-6-25) J.B.D. EXPERIMENTAL REPORT. -3- Expl. No. REF. Hs{Lord Ernest Hives - Chair}/RmL/LG17. 8. 25. side steering tube springs we tried against standard were very weak and would undoubtedly promote low speed wobbles. Rating - standard. S.S. spring 3,500 lbs/1". " - weak. " " 1,000 lbs/1". (d) Increasing transverse inertia of axle. We carried out a test fitting lead bands round the brake drums. These weighed 50 lbs. each. The result was to lower the period of the wobble from a min. of 54 m.p.h. to a minimum of 48 m.p.h. and to increase its amplitude and intensity somewhat. Therefore any reduction we can make in the weight of the tyre, wheel or drum will assist us in this particular trouble of high speed wobbles. (e) Increase of weight on front of car. Though owing to the fact that 5-EX (Silver Ghost) will not wobble, we have been unable to ascertain definitely the effect of adding weight to the sprung portion of the front of the car, we have two reasons for expecting this to make a difference. (1) Wobbles are always [s]a[/s] worse on retard when there is more weight on the front of the car than when accelerating. (2) Braking throws the weight on the front axle and frequently brings up wobbles. We know that increasing the front axle loading will definitely lengthen its parallel period. This may affect high speed wobbles though Healy says Criss Cross period most important. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||