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).
General table of specifications for relay switch gaps.
| Identifier | ExFiles\Box 64\3\ scan0206 | |
| Date | 16th February 1926 guessed | |
| X7650 GENERAL TABLE FOR RELAY SWITCH GAPS 1/2 Position. Gap on upper contact. Gap between pole core & armature. Gap on lower contact. Gap at carbon contacts. OFF O A + B δ B -Ec. Carbons in contact 1/2 C A+B-C δ (B - C) O ON 1/4 B A O E (B - C) | ||