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 make ratio versus speed curves for a standard contact breaker with standard and increased rated springs at various gaps.
| Identifier | ExFiles\Box 32\5\ Scan057 | |
| Date | 31th March 1937 | |
| SPS X7390 MAKE RATIO NORMAL RUNNING SPEED 700 r.p.m. .010" GAP .015" GAP .025" GAP MAKE RATIO - SPEED CURVES OF R STANDARD CONTACT BREAKER WITH STANDARD AND INCREASED RATED SPRINGS. SPEED (r.p.m.) STD. SPRING (LOAD ON POINTS .9 LBS) STRONGER SPRING (LOAD ON POINTS 1.4 LBS) AERO 30-3-37 E.F.C. 31/3/37 | ||