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).
Calculations for front and rear brake lever ratios for a Girling System on a 3-B-IV model.
| Identifier | ExFiles\Box 120\3\ scan0147 | |
| Date | 11th March 1935 | |
| 24456 HE/AFM.{Anthony F. Martindale}14/KW.11.3.35. Girling System for 3-B-IV. The present ratio of levers from foot pedal to one shoe is Front 17.5 Rear 20.5 Owing to the greater efficiency of Girling brakes it is estimated that this could be reduced to Front 14 Rear 16.3 For simplicity's sake it is however proposed to use Front 16 Rear 18.7 which is between the two, and the linkages would be as follows - Rear. The lever ratio on Girling's axle is 6 x 2.125 / .9375 = 13.6 The lever ratio at present on the car except for the big lever on the rear axle is 1.38. And these two together give a ratio of 18.7 to the rear. Front. Ratio on car at present including equaliser shaft is 1.6. Ratio on Girling's axle is 6 x 2.6 / 1.25 = 12.5 By re-drilling the 2.6" centres lever to 2.1" ratio becomes 10.0. And these together give 16. | ||