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 for front wheel brake torque and weight transfer during deceleration.
| Identifier | WestWitteringFiles\K\November1923\ Scan65 | |
| Date | 22th November 1923 | |
| R.R. 492A (40 H) (SL 42 12-7-23). J.H., D.{John DeLooze - Company Secretary} ORIGINAL EXPERIMENTAL REPORT. Expl. No. 1559 49940 REF:Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer}2/LG22.11.23. To Da.{Bernard Day - Chassis Design} from Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} FRONT WHEEL BRAKES. We gave the figure of 40,000 inch.lbs. as the maximum torque likely to be imposed on the front axle. We obtained this outside figure as follows :- It can be shewn mathematically that when a car decelerates at ft.per sec², the change in the fraction of total the weight on the front wheels is hf{H. W. Frost - Coachwork Inspector}/gl{G. Linnett} where h = ht.of centre of gravity, l = wheelbase, g = accn.due to gravity. Assuming for a closed 40/50 HP. car (Guaranteed wt. 55 cwts. - long wheelbase) - (a) C. of G.{Mr Griffiths - Chief Accountant / Mr Gnapp} located 32" from ground. (b) .56 of the weight acts on the rear wheels statically. (c) Greatest coefficient of friction to be met = .72. (d) The car weighs 55 cwts. (e) The brakes can lock the wheels against any torque we are likely to get. (f) The decn. we get with four wheel braking is about 24 f.p.s². (g) Static weight on rear wheels (40/50) = .56 of total car weight. Change in fraction when decelerating at 24 ft. per sec². = hf{H. W. Frost - Coachwork Inspector}/gl{G. Linnett} h=32 l=150 f = 24 ft. per sec². hf{H. W. Frost - Coachwork Inspector}/gl{G. Linnett} = (32x24)/(150x32) = .16. New fraction on the rear wheels = .56 - .16 = .4 total wt. New fraction on the front wheels = .6 " " That means the load on the front axle when decelerating is contd:- | ||