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 and notes for a non-servo brake scheme, including different ratios and adjustments.
| Identifier | ExFiles\Box 120\2\ scan0330 | |
| Date | 10th June 1938 | |
| B.56.BN.{W.O. Bentley / Mr Barrington} BRAKES - SCHEME (1). No Servo. Pedal travel 6". Rear brakes, Girling, with floating fulcrum with torque mult. factor of ............... 1.3 Pedal ratio to rear brakes. (14 x 5 x .595 x 2 x 6.32) / (3 x 3.95) = 44.5:1 Effective Ratio 44.5 x 1.3 = 57.8:1 Front brakes Lockheed torque mult factor 1.7 Master cylinder 1.00" dia. wheel cylinder 1.25" dia. Pedal ratio (14 x 5 x 4 x 1.23) / (3 x 3.95 x .785) = 37:1 Effective ratio 37.1 x 1.7 = 63.2 Ratio Front to rear 1.09 (1) With the above ratios it was possible to press the pedal to the boards with only 60 lbs pressure owing to sponge in the equalizer which was badly lined up. The brakes were not effective. (2) We then stiffened up the equalizer and improved the alignment, This effected a slight improvement but it was still possible to push the pedals to the boards. (3) We fitted a cross member to take the upward thrust from the equalizer and decreased the ratio to the front to 22.2:1 and to the rear to 26.60:1 by moving the link on the brake pedal and equalizer arm. Rear - (14 x 4 x 632 x .595 x 2) / (4 x 3.95) = 26.6:1 Front - (14 x 4 x 4 x 1.23) / (4 x 3.95 x .785) = 22.2:1 Front to Rear - (22.2 x 1.7) / (26.6 x 1.3) = 37.8 / 34.5 = 1.09 With this arrangement it was not possible to press the pedal to the board but the pedal pressure required to stop the car was excessive. | ||