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).
Instructions for setting and measuring the gaps on a push button switch.
| Identifier | ExFiles\Box 34\3\ Scan040 | |
| Date | 27th August 1919 | |
| X.2641 27.8.19 PUSH BUTTON SWITCH. Switch set up as above and connected to battery, resistance and ammeter. Turn micrometer until carbons are just in contact - which will be indicated by a deflection of ammeter needle. The micrometer reading will give the depression of button necessary to make carbon contact. This should be .020" +7/- The carbon gap will then be .020" x 45/23 = .039", say .040" +/-15 The copper gap, when carbons are just closed, can be measured by thickness gauge after removing cover of switch. This copper gap should be .330" +/-10. Multiplying this by 23/30 will give the 2nd. depression of push button necessary to make copper contact after carbons have just closed. | ||