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).
Testing different brake servo friction materials and investigating pressure loss issues.
| Identifier | ExFiles\Box 30\6\ Scan186 | |
| Date | 2nd February 1924 | |
| R.R. 493A (40 H) (SL 42 12-7-23). J.H., D.{John DeLooze - Company Secretary} EXPERIMENTAL REPORT. ORIGINAL. Expl. No. 9940 3407 REF: Hs{Lord Ernest Hives - Chair}9/LG22.2.24. To R.{Sir Henry Royce} from Hs.{Lord Ernest Hives - Chair} c. to CJ. RG.{Mr Rowledge} c. to DA.{Bernard Day - Chassis Design} H.{Arthur M. Hanbury - Head Complaints} c. to BY.{R.W. Bailey - Chief Engineer} W.O.R. SECRET. BRAKES. -------- It would appear possible to use a different friction material on the servo to that used on the brakes themselves. We have on order some Ferodo fibre which has a much higher co-efficient than our braking material and is quite satisfactory up to temperatures of 100°C. Also we propose trying the cotton fabric similar to that we have used successfully on the 40/50 HP. clutch. This has a higher co-efficient than the asbestos material. We have caried out now a number of tests with the slow speed servo as arranged by Rg.{Mr Rowledge} If we run continuously with the brakes on under power, we can get the brakes on the wheels nearly red hot, whereas, the temperature of the servo does not exceed 50°C or 60°C. On this car we are, however, doing a lot of work by direct pedal pressure - the output from the servo is not as much as it should be. We found on this car that we were getting unequal distribution of pressure and also considerable loss. This we proved was caused by the equaliser between the front and rear brakes. This is a standard differential type equaliser. With light loads, the loss is not much but with the big loads from the servo, the loss is excessive and occurs mostly on the front. Hs.{Lord Ernest Hives - Chair} | ||