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).
Calculations and findings on steering moments and car behavior during turning and braking.
| Identifier | ExFiles\Box 66\5\ scan0022 | |
| Date | 12th June 1925 | |
| H.R. 493a (50 H) (D.D. 31, 12-6-25) J.H.D. EXPERIMENTAL REPORT. -2- Expl. No. REF Hs{Lord Ernest Hives - Chair}/Rml/LC7.9.25. Suppose the car is to be trying to turn about O as the rear wheels cannot skid sideways. Then taking moments about O m f / g x t / 2 = P x l. Now for a normal car - l = 10 ft. t = 4 ft. M = 4480 lbs. f = due to one wheel being locked = 5 ft/sec2 .. P = 4480 X 5 X 4 / 32 X 2 X 10 = 140 lbs. If the weight of the pivot centre about the ground is 16" and the angle of castor is 1° 30', the distance Y = 16/12 tan 1° 30' = 1.33 X .026 ft. = .0345 ft. .. Moment tending to steering the car :- = .0346 X 140 lbs.ft. = 4.85 lbs.ft. an almost negligible amount being a pull of only 3 1/2 lbs. at the tyre tread. A further experiment shewed that the force referred to is so small as to be almost negligible in practice. The practical method of demonstrating this was to hold the front axle absolutely rigidly in torsion, by means of a device something after the nature of that fitted on the 'Beardmore'. It was then found that though the conditions remained specifically the same as for the previous mathematical assumption, the steering had practically no tendency to be affected when this axle control rod was fitted, whereas, without it the application of one front brake only would cause the car to dive towards the side being braked. contd:- | ||