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).
Description of a brakes system, incorporating a servo motor and hydraulic linkage, intended for a patent application.
| Identifier | ExFiles\Box 120\2\ scan0317 | |
| Date | 18th May 1938 | |
| 1029 To NW.{N. Walker - Patents} from Rm{William Robotham - Chief Engineer}/AFM.{Anthony F. Martindale} Rm{William Robotham - Chief Engineer}/AFM.{Anthony F. Martindale}2/MH.{M. Huckerby}18.5.38. The following is a description of the brakes system for which we want to file a patent:- The rear brakes are connected to the pedal by ropes and are not servo operated. The hand brake lever is linked up to the same set of rods. The rods operate a mechanical servo motor which, by means of an asymmetrical cam operates a single master cylinder. This master cylinder operates the front brakes. In the event of this system being used on a car of such weight that it is impossible to operate the rear brakes by direct action alone, it is possible to take an additional pipe line from the master cylinder to give hydraulic assistance to the rear brakes. The advantages of this system are as follows:- It is necessary to have on every car a mechanically operated hand brake, and if it is desired that this hand brake shall be something more than a parking brake it is necessary to construct the rods in a sound manner. If these rods are so constructed they can be used for the foot brake also. With independent suspension the mechanically operated front brake becomes so complicated that the hydraulic linkage to the front brakes leads to considerable simplification. On a car of 30 cwts. or more it is not easily possible to operate the brakes by foot pressure alone if this pressure is not to be excessive, and if there is going to be a considerable reserve of travel on the pedal. On such a car a servo is essential. By using a servo to operate the front brakes alone the system is kept as simple as possible. The advantage of an asymmetrical cam on the mechanical servo is that the front braking when the car is travelling in the forward direction is more powerful than when the car is travelling backwards, and further, this arrangement permits of higher speed of rotation of the servo motor. In the event of failure of the hydraulic lines the rear brakes are unaffected, and in the event of a failure of the rear brake rope a stop in the linkage makes it possible for the pedal to operate the servo motor and, therefore, the front brakes: this scheme is already employed on Wraith. We think that this system has the least possible number of parts, bearing in mind that it is a servo assisted system. Rm{William Robotham - Chief Engineer}/AFM.{Anthony F. Martindale} | ||