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).
Description of the operation of a push-button combination switch for controlling two circuits, used for aircraft engine starting.
| Identifier | ExFiles\Box 168a\2\ img198 | |
| Date | 4th December 1935 guessed | |
| /6139. SWITCH CX.{Major Len W. Cox - Advertising Manager}70608 This switch is of the push button type and is designed for controlling two circuits, each circuit separately or both together and with the operating knobs protected against accidental operation. One application is for the starting of aircraft engines, where it is desirable to have a switch for operating a starter circuit and a switch for operating a trembler coil ignition circuit, either of which operations may be required separately. Where it is required to operate both simultaneously as in normal starting, it is convenient to have a combination switch so that only one hand need be used. Referring to the drawing A is a knob which is depressed to switch on the trembler coil, and B is a knob which is pulled to switch on the starter either directly or through the medium of a separate solenoid switch. The knob B is made to surround the knob A so as to protect the knob A against accidental operation, the protecting flange, however, being cut away at C to permit the insertion of the operators thumb for operating the knob A.{Mr Adams} It is evident that it is quite easy to depress knob A, or to pull knob B or to do both simultaneously. | ||