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, gaps, and arrangement for a duplex push button switch.
| Identifier | ExFiles\Box 64\4\ scan0281 | |
| Date | 24th May 1929 | |
| X 7655 BY/RD. from EFC. EFC6/D24.5.29. DUPLEX PUSH BUTTON SWITCH. When it was proposed to use this switch previously, we went into the question of the gaps and arrived at gaps in accordance with the following table :- Position. Button depression. Copper gap. Carbon gap. Off A + .000 .035+5 -3 .019+13 -8 Carbons A+ .010+7 -4 .020+3 -5 0 in contact. Coppers A+ .024+4 -2 0 0 in contact. where A = initial button depression which should be .012". Owing to our specification of production inspection and test not having been issued at the time, apparently we did not get your drawing D71122 altered to suit. We should be pleased if you would now arrange to incorporate gaps in accordance with the above table on the arrangement drawing of this switch. We also take this opportunity of confirming Mr. West's arrangements with you to alter the relative rating of the carbon contact back and under springs, so that in no position of the switch does the under spring become compressed. It will be agreed that the function of this under spring is merely to keep the lower carbon contacts pressed against the fixed contact plate. EFC. | ||