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 servo efficiency of front wheel brakes for the 'India' model.
| Identifier | ExFiles\Box 78\2\ scan0039 | |
| Date | 25th September 1924 | |
| R.R. 493A (50H) (D.B. 175 25-9-24) J.H.D. EXPERIMENTAL REPORT. Expl. No. V5375 REF Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer}2/LG27.5. To DA.{Bernard Day - Chassis Design} from Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} SECRET. V5375 V5770 V5940 'INDIA' FRONT WHEEL BRAKES. It is apparent that with the present leverages on 'India' we shall require a servo efficiency 1 if the maximum braking to the front wheels is to be 40½% of the total. It would seem to be inadvisable to make it more than this, as the static % of the total weight of the car on the front axle is less on the 20 HP. than the EAC. With a servo efficiency of 1, the available braking units on the 20 HP. are 1225. With the mean standard servo efficiency on the EAC. the available braking units are 2050, or 1.67 that of 'India'. The weight of an EAC. car is 1.37 times that of 'India'. Therefore with this servo efficiency 'India' will require 27½% more pedal pressure than the EAC. to produce a given retardation. This seems very undesirable as the 20 HP. is a lighter car, and in consequence the remainder of the controls are lighter than those of the EAC. A further objection to the use of a servo with an efficiency as low as 1.00 is that any slight variation of the servo efficiency will make a large variation in the proportion of front to rear braking. We suggest that we endeavour to obtain a servo efficiency of 1.5 and at the same time reduce the servo contd :- | ||