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 effects of vehicle weight and gradients on braking performance and stopping distances.
| Identifier | ExFiles\Box 178\1\ img074 | |
| Date | 12th October 1925 | |
| - 12 - REF. Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer}2/LG121025. Weight of the car. If all the wheels of the car are locked the distance in which it will stop is entirely independent of the weight of the car. With the R-R front wheel brake system, the type of body makes a slight difference because the front wheels are not locked when indulging in max. braking, this however, may be neglected in any but tests carried out with scientific instruments. In cars with rear wheel brakes only, the proportion of the weight of the car over the rear axle dictates its maximum rate of retardation. Gradients. As has been pointed out under acceleration, upward gradients have a definite value as retardation, and downward gradients as acceleration. When braking down-hill, there, the car will have a max. retardation which will be the rate at which it could pull up on the level on the same surface minus the acceleration due to the gradient. Conversely, up hill, the car can be pulled up more quickly than on the level, the retardation due to the gradient being added to that due to the surface. Example = .7 Level - distance to rest from 40 m.p.h. - 75 ft. Up hill) " " " " " " " - 58 ft. 1 in 5 ) Down-hill) " " " " " " " - 102 ft. 1 in 5 ) Distance to rest. On any surface with a fixed co-efficient of friction and a given amount of braking, the distance (contd). | ||