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).
The testing of a Lucas Ignition Switch, Type No. M & N - 30.
| Identifier | ExFiles\Box 168a\2\ img394 | |
| Date | 20th September 1936 | |
| To By.{R.W. Bailey - Chief Engineer} c. Da.{Bernard Day - Chassis Design} c. Hy{Tom Haldenby - Plant Engineer}/KL. 61371 re Lucas Ignition Switch. Type No.M & N - 30. The above switch is similar in design to that fitted to the F.F. Jaguar Car. We assume that if this switch were used, either by itself or as part of a larger switch, it would have to carry the full current passing through the switchbox but would only have to break the ignition circuit. A general heating test was carried out in which a current of 20 amperes was passed through the switch for a period of one hour, the heating appeared to be reasonable. The switch was then submitted to an endurance test which consisted of mechanically operating the switch so as to 'make' and 'break' a circuit containing a standard ignition coil with series resistance connected in parallel with a 24 watt lamp, the switch controlling a current of approximately 3 amperes. Under these conditions the switch functioned smoothly for 60,000 operations. After this a slight flickering was observed in the 24 watt lamp, this gradually became worse until at 68,615 operations the switch failed to make contact. On dismantling it was found that a groove had worn in the track of the moving contact, on the bakelite base and the failure was due to blackening of one of the fixed contacts, this was partly the result of sparking and partly due to particles of bakelite being dragged into the contact. The switch gives a good performance when subjected to the above conditions we do not recommend that it should be made to break more than 3 amperes. In taking the volt-drop, the figures given are the minimum and maximum of three readings, the switch being operated in each case. It will be noticed that the values obtained, although reasonable, are rather inconsistent, this is due to the design of the contacts, the contact area of which is at a minimum value. Cont'd......... | ||