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).
Clarifying 4-wheel brake distribution calculations and comparing braking percentages for different setups.
| Identifier | ExFiles\Box 5\3\ 03-page131 | |
| Date | 25th May 1925 | |
| 5940 To Hs.{Lord Ernest Hives - Chair} from DA.{Bernard Day - Chassis Design} c. to R.{Sir Henry Royce} S E C R E T. DA{Bernard Day - Chassis Design}2/M25.5.25. I N D I A.{Mr Adams} X.5940 X.8420 X.9940 X.9910 4-WHEEL BRAKES - BRAKE DISTRIBUTION. Referring to your Hs{Lord Ernest Hives - Chair}4/LG20.5.25., we should like to point out that the information given on the diagram of curves is liable to be misleading because the units giving the rear and front braking are not the same as those on the similar information previously given for EAC.3. We attach a short explanation of what we mean :- *The diagram of braking given with Hs{Lord Ernest Hives - Chair}4/LG20.5.25., cannot be compared with the similar diagram given for EAC.3. and referred to in Hs{Lord Ernest Hives - Chair}1/LG9.7.24. because the latter is based on a multiplication of torque whereas the former is worked out on a basis of rod loads, so called conventional servo multiplication. *That the diagram for EAC.3. is based on torque multiplication is confirmed by Hs{Lord Ernest Hives - Chair}/ACL/L33.6.24., where the rod loads are converted to torque multiplication, and for a 55° cam a figure of 2.5 is obtained, which agrees with the range given on the diagram of 1.500 - 2.500. *According to Hs{Lord Ernest Hives - Chair}/Rz/LG20.5.25., for India, the ratio input over output measured in the 'conventional' method is 1.250., output over input = .800. *If this value .800 is applied to the diagram of braking for India a correct interpretation is obtained, and it is found that the percentage of front braking is 37%, and rear 63%. *For EAC.3. with reduced braking as Hs{Lord Ernest Hives - Chair}1/LG9.7.24., with a mean servo torque multiplication of 2.0 the front braking is 40%, and the rear 60%. Before the braking was reduced on EAC.3. the front was 44%, and the rear 56% - see diagram ACL/26.6.24. *Tabulated, the figures are :- India. EAC.3. as reduced. EAC. before reduction. *Front. 37% 40% 44% *Rear. 63% 60% 56% __ __ __ *Ratio .588 .666 .785 F/R.{Sir Henry Royce} contd :- | ||