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).
Replying to a query about the comparability of braking units and servo multiplication between different models.
| Identifier | ExFiles\Box 5\3\ 03-page136 | |
| Date | 25th May 1925 | |
| R.R. 487a (Dev) (D.O. 15) 15-9-34 J.H.D. EXPERIMENTAL REPORT Exptl. No. X5940 REF Hs{Lord Ernest Hives - Chair}/Rml/1.027.5.25. Handwritten: X5940 X5770 X5375 To DA.{Bernard Day - Chassis Design} from Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} In reply to your DA{Bernard Day - Chassis Design}2/M25.5.25, you state that the units giving the rear and front braking of 'India' are not the same as those previously given for the EAC. The braking units are precisely the same in each case and are - Load in can link X drum dia. You also state that the "diagram of braking given with Hs{Lord Ernest Hives - Chair}4/LG20.5.25 cannot be compared with a similar diagram given for EAC.111". We should like to point out that these two diagrams are comparable in every way. The reason for this is that the servo "multiplication of torque" units given on the EAC. diagram happen, owing to the servo lever dimensions, to be, for all intents and purposes, identical with the "conventional servo multiplication" units. Actually when the conventional multiplication is 1, the torque multiplication is 1.04", a difference which is negligible as the servo efficiency varies at least 20% in practice under various speeds and extremes of brake application. This means that if the conventional servo multiplication figure for each servo is taken, the % of front braking which can be obtained on each car can be read off directly from the two sets of curves respectively. Likewise the braking units available to front and rear. We used the "conventional servo multiplication" efficiency units in this case for simplicity - we are already using conventional units for "braking available". | ||