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 modifications for a Duplex Press Button Switch, including a table of gaps.
| Identifier | ExFiles\Box 64\3\ scan0281 | |
| Date | 3rd July 1926 | |
| To EFC. BY/RD/ML1 3.7.26. DUPLEX PRESS BUTTON SWITCH - E.A.C.V11. We have today instructed to RHC.{R. H. Coverley - Production Engineer} the packing suitable to produce the modified gaps as attached - these are not quite the same as yours because we have had to correct the dimensions on the moving arm. We also give below the gaps as shown on LeC.2] 99. RECEIVED 13 JUL 1926 | Position. | Button depression. | Copper gap. | Carbon gap. | |---------------------|--------------------|-------------|-------------| | Off. | .012 + .000 | .090. | .060 | | Carbons in contact. | .012 + .038 | .035 | 0 | | Coppers in contact. | .012 + .068 | 0 | 0 | BY/RD. | ||