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).
The variations of the four-wheel braking system, including brake force distribution and the effects of maximum braking on steering.
| Identifier | ExFiles\Box 178\1\ img092 | |
| Date | 1st July 1924 | |
| Hs{Lord Ernest Hives - Chair}2/LGS.7.24. POSSIBLE VARIATIONS OF THE RR. FOURWHEEL BRAKING SYSTEM. As stated previously, the leverage is so proportioned that of the total braking effort - 40% goes to the front brakes while the remaining 60% goes to the rear. This distribution depends upon the condition of the brakes themselves because the system cannot compensate for any brake which may be ineffective through inaccurate bedding or oil. The condition of the road surface, the weight of the car and the height of the centre of gravity, are points which have important bearing on the braking because once either the rear or front brakes lock, the retarding force due to those brakes is lessened and the distribution ratios are no longer the same as they were up to the point of locking. We do not, at any time, wish to get the maximum braking on the front wheels. The reason for this is that with the maximum braking on the front, the torque will twist the axle forward and affect the steering. This will be obvious when it is appreciated that the standard lean for the front pivots, when the car is level, is approx. 1° to 1.5° backward in order to provide self-centering or castoring action. If the maximum braking is put on to the front axle, it is possible for the axle to be twisted so that the pivots are actually leaning forward several degrees. If the steering is turned when the axle is twisted forward, there is a risk that it will take charge and run on to full lock. (contd). | ||