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).
Notes on the advantages of the semi-servo four-wheel brake system over other known systems.
| Identifier | ExFiles\Box 73\3\ scan0135 | |
| Date | 1st July 1924 | |
| Hs{Lord Ernest Hives - Chair}5/LGS :7. 24. NOTES ON ADVANTAGES OF THE RR. SYSTEM OF FOUR WHEEL BRAKES OVER OTHER KNOWN SYSTEMS. The RR. semi-servo system possesses several advantages over other systems in general use. These advantages all mean increased safety and reliability. The R.R. system retains the characteristics of the standard R.R. rear brakes plus the addition of front brakes - a servo is fitted to provide the necessary additional power for operating the front brakes and to assist the foot pressure for the rear. This allows less brake pedal pressure and still retains the same clearances for the brakes and the same pedal movement. If we imagine the servo cut out of operation on the R.R. system, we should then have exactly the same braking on the rear wheels as we have had for years on the standard 40/50 HP. R.R. car. On the other hand, if we imagine the servo cut out on other makes of car, the braking would be below the standard of that found on cars fitted with rear brakes only. The reason for this is that on other makes of car, direct pedal pressure is distributed to the four brakes. This means there are four pull off springs to be overcome instead of two, and numerous additional mechanism to be operated which would have friction losses. The advantage to be derived from retaining the standard rear brake is appreciated when shunting the car in a confined space. With servo systems it is necessary for the car to move a certain distance, after the brake pedal contd:- | ||