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).
Table of gap measurements for a main and auxiliary switch unit at different operational positions.
| Identifier | ExFiles\Box 64\4\ scan0225 | |
| Date | 18th March 1929 | |
| X7655 18.3.29. MAIN AND AUXILIARY SWITCH UNIT CAP TABLES. SCHEME OR UNIT:- D.{John DeLooze - Company Secretary} MAIN SWITCH. Position of switch. Air gap at core centre. Core to armature stop. Copper gap (first blade to make). Carbon gap. Off. .086✓ .093✓ .060 .025✓ Carbons just in contact. .069✓ .077 .040✓ O Auxiliary switch carbons just in contact. .049✓ .054✓ .010✓ O Coppers just in contact. .045✓ .045✓ O O Full on. .010✓ O O O Mutual gaps :- Full off .016✓ Full on. .011✓ AUXILIARY SWITCH : Position. Air gap at core Gap between pole core & arm: stop. Gap at upper contact. Gap at lower contact. Gap at carbon contcs. Off. .079✓ .080✓ O .041✓ O Carbons just breaking. .064✓ .061✓ .020✓ .013✓ O Just making on lower contact. .055✓ .050✓ .034✓ O .018✓ Full on. .012 O .096✓ O .101✓ EFC. | ||