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).
Page of calculations and analysis regarding servo braking efficiency for car 18-EX, comparing different cam angles.
| Identifier | ExFiles\Box 17\3\ Scan346 | |
| Date | 21th December 1928 guessed | |
| contd :- -4- DIRECT : 16.65/6.25 x 1.375/1.725 x 2.00/2.00 x 1.875/4.00 x 2.85 x 16.2 = 21.5 SERVO REAR : 16.65/6.25 x 1.37/1.725 x 2.125/2.00 x 2.85/4 x 16.2 x S = 26.5 X S = 26.5 X .85 = 22.3 SERVO FRONT : 16.65/6.25 x 1.37/1.7 x 1.75/1.75 x 14.5 x .85 = 26.6 This gives 37.6%xxxxx to the front - assuming the higher value of µ= .2 the % to the front becomes 41. We think that on 18-EX as it left for France the % to front was about 35 but can say more accurately when we have measured the servo efficiency with spring balances. We think that 45° cams are more desirable than 30° cams though the latter appeared to operate satisfactorily on this car. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||