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 modifications to address complaints of insufficient front brakes and the ease of back brake locking.
| Identifier | ExFiles\Box 111\3\ scan0226 | |
| Date | 23th January 1939 | |
| -2- Rm{William Robotham - Chief Engineer}/JBD.{John B. Dixon - Fuel Systems}14/JH.23.1.39. With the designed ratios we had complaints of insufficient front brakes which were justified when the rear linings had to be replaced though the front were hardly worn. The pedal ratio then was - Front - 33.7 x S = 91. Front = 1.225. Rear - (31.3+15.9S) = 74.2 Rear. S being the servo multiplication factor which equalled 2.7 with the RAD.13 lining. Changing the Servo lining to VG.90 reduces S to 2.250. Making the designed ratios - Front 33.7 x 2.250 = 75.8 Front Rear 31.3 + (15.4 x 2.250) = 67.1 Rear (75.8 Front / 67.1 Rear) - 1.13. The second complaint was the ease with which the back brakes locked. To overcome this we have reduced the back brakes 10% by increasing the length of the levers on the top of the rear equalizer from 1.125" to 1.250". This gives a pedal pressure of 70 to 80 lbs. to lock the rear wheels. Front 75.8 / Rear 60.4 = Front / Rear = 1.255. There was still insufficient front braking. This has been increased by altering the idler lever on the crankcase to give us a step up of (6.625 / 5.625) giving. Front. 89.2 = Front / Rear 60.4 = 1.475. | ||