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).
Bar chart comparing critical air temperatures for spring tensioned versus positively tensioned fan belts.
| Identifier | ExFiles\Box 24\5\ Scan244 | |
| Date | 2nd July 1938 guessed | |
| 19 E.X. 62 M.P.H. No BONNET VENTILATION GRAPH V.{VIENNA} COMPARISON OF SPRING TENSIONED FAN AND FAN BELT TENSIONED POSITIVELY. CRITICAL AIR TEMP 10°C 20°C 30°C 40°C SPRING TENSIONED 40.5 BELT TIGHTENED CHOC à BLOC 44.5 | ||