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).
Servo braking lag and its effectiveness and safety in both forward and reverse directions.
| Identifier | ExFiles\Box 73\3\ scan0136 | |
| Date | 1st July 1924 guessed | |
| contd :- -2- is depressed, before the assistance from the servo can be felt. This we call the 'lag' of the servo between the time the pedal is pressed and the brakes are effectively applied. As an example of the advantage, let us assume a car to be shunting in a garage, when it becomes necessary for the car to stop in a few inches to avoid it hitting some object which may not be visible to the driver but of which he has received warning from an observer, under these conditions no servo will operate so that unless the direct braking is sufficient to hold the car, the car will travel forward until the servo 'lag' has been overcome. By this time it is possible that damage has been done to the car. The R.R. ^Servo system is <strikethrough>at present the only one on which the servo is</strikethrough> operative either when the car is going forward or on reverse. It is considered very desirable that the braking should be equal in both directions. On other makes of car in which the servo only works in the forward direction, it may take 6 or 7 times the pedal pressure when going on reverse to obtain the same degree of braking. This may prove very dangerous - as an instance - a lady might drive the car and find that in the forward direction the brake pressure was such that she could hold the car with ease, if, however, she came to a steep hill and happened to miss the gear and the car ran backwards, it might be physically impossible for her to apply sufficient pressure to hold the car. Again, with an expert driver, if he is turning the car round on the road, it is difficult contd:- | ||