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 on washer surface torque and coefficient of friction under various conditions.
| Identifier | ExFiles\Box 94\1\ scan0208 | |
| Date | 10th October 1935 | |
| -2- HS{Lord Ernest Hives - Chair}/WB.{Mr Brazier/Mr Bell}3/KW.10.10.35. First Table: WASHER SURFACE | Initial | Final --- | --- | --- | Torque lbs/ft. | C.O.F. | Torque lbs/ft. | C.O.F. Soft | Well Lubricated | 16 | .112 | 24 | .168 | Wiped Dry | 20 | .140 | 27 | .189 Hard | Well Lubricated | 15.5 | .108 | 23 | .161 | Wiped Dry | 25 | .175 | 25 | .175 The above tests were repeated with the contact surface reduced to .7854 (1.450² - 1.350²) = .225 sq.", the mean radius being .700". Second Table: WASHER SURFACE | Initial | Final --- | --- | --- | Torque lbs/ft. | C.O.F. | Torque lbs/ft. | C.O.F. Soft | Well Lubricated | 18 | .153 | 22 | .182 | Wiped Dry | 22 | .182 | 22 | .182 Hard | Well Lubricated | 19 | .161 | 22 | .182 | Wiped Dry | 24 | .204 | 28 | .238 | ||