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).
Graph showing the torque vs. angular deflection characteristics for new and worn Hardy couplings.
| Identifier | ExFiles\Box 74\3\ scan0026 | |
| Date | 4th April 1919 guessed | |
| NEW AND WORN HARDY COUPLING CHARACTERISTICS TORQUE-LB FT ANGULAR DEFLECTION 0 100 200 300 400 500 600 0 1º 2º 3º 4º 5º 6º 7º HARDY NEW HARDY 4000 MILES HARDY WORN BADLY | ||