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).
Specifications and ratios for the Main and Relay Switch Unit.
| Identifier | ExFiles\Box 64\3\ scan0187 | |
| Date | 3rd November 1924 | |
| X.8650. EFC8/T3.11.24. X.8650 MAIN AND RELAY SWITCH UNIT. MAIN SWITCH. Fulcrum to core 1.250" Fulcrum to copper contact. 2.175" Fulcrum to carbon contact. 3.050" Ratio copper contact arm / core arm = 1.740 α Ratio carbon contact arm / core arm = 2.440 β Ratio Carbon contact arm / copper contact arm = 1.400 γ RELAY SWITCH. Fulcrum to core and fulcrum to upper contact 1.250" Fulcrum to lower contact 2.800" Fulcrum to carbon contact. 2.775" Ratio Lower contact arm / Upper contact or core arm = 1.760 8 Ratio Carbon contact arm / Copper contact or core arm. = 2.22 6 Ratio Carbon contact arm / Lower contact arm = 1.260 3 EFC. | ||