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).
Test results for various materials, measuring the co-efficient of friction at 150°C and 500°C.
| Identifier | ExFiles\Box 74\2\ scan0241 | |
| Date | 12th December 1918 | |
| R.R. 235A (500 T) (S.D. 408. 26-4-17.) Bm. 2/156/13. 12th December 1918 X.3409. TEST RESULTS Temperature up to 150° Centigrade. (approx) Description of material | Duration of test in mins. | Area in Sq. ins. | Pressure per sq. ins. | Speed in ft. per min. | Total Amps. | Co-efficient of friction. No. 30 | 30 | 9 | 10 | 5,000 | 37 | .36 F.B.A. No. 9 | 30 | 9 | 10 | 5,000 | 37 | .36 F.B.A. Standard | 30 | 9 | 10 | 5,000 | 37 | .36 Temperature at 500° Centigrade. (approx) No. 30 | 3 | 9 | 10 | 5,000 | 27 | .146 F.B.A. No. 9. | 3 | 9 | 10 | 5,000 | 39 | .41 F.N.A. Standard | 3 | 9 | 10. | 5,000 | 34 | .293 ----------- | ||