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 report comparing the performance of various servo linings.
| Identifier | ExFiles\Box 87\5\ scan0033 | |
| Date | 26th October 1934 | |
| -3- Hm{Capt. W. Hallam - Head Repairs}/PJH.7/KW. 26.10.34. SERVO LINING TESTS. Type of Servo Lining. | Average /u when cold | Decrease in /u when hot per cent | Remarks. Ferodo RAD.13 | 0.44 | 47 | Present standard. Long life. Silent. Ferodo S.3914 | 0.43 | 38 | Squeaks. Ferodo FF239 | 0.30 | 35 | Judders. Cotton X5370 | 0.50 | - | Violent judders prevented completion of test. Cotton Duck | 0.38 | 18 | Short life. Judders. Roasted RAD13 | 0.37 | 3 | Short life. Squeaks. Roasted S3914 | 0.36 | -14 | Short life. Squeaks. Ferodo M.Z. | 0.44 | 35 | Long life. Silent. Ferodo B.Z. | 0.42 | 39 | Long life. Silent. Ferodo VH.20 | 0.34 | 54 | Long life. Silent. Mintex Lamina | 0.45 | 12 | Violent squeaks. Mintex ZS | 0.41 | 17 | Long life. Ferodo S4419 | 0.60 | - | Wear so rapid that test could not be completed. Ferodo S4947 | 0.47 | 30 | Objectionable smell. | ||