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).
Testing, risks, and standardization of battery ignition coils.
| Identifier | ExFiles\Box 69\1\ scan0290 | |
| Date | 3rd January 1930 | |
| By.{R.W. Bailey - Chief Engineer} from EFC. c. Wor.{Arthur Wormald - General Works Manager} X8710 EFC5/AD3.1.30. X.8710. BATTERY IGNITION COILS. We have received the two ignition coils mentioned in the note By/RDL/DM{D. Munro}31.12.29 as being made up with secondary insulation of reduced amount as described therein. We note from the last paragraph that it is proposed to adopt such coils on production forthwith. With this we do not agree until we have tested out such coils to our satisfaction. We think it a risky departure from standard to reduce the insulation between the secondary layer, particularly in the case of the first few layers in view of the fact that we have yesterday experienced on special test a failure in those layers of an ignition coil (L.C.type) constructed with 5 turns of insulating paper between them. We do not advocate any such radical departure from standard until we have completed results of a number of tests at present in hand on various experimental coils, which tests are being pushed forward with all possible speed. It has been determined by experience that the usual 10,000 mile chassis test of various experimental ignition coils is not reliable as a basis for standardisation, and with this in view we have developed a series of tests for coils which we estimate, in the light of our experience to date, to be of a nature and intensity suited to taking the place of the 10,000 mile chassis test demanded in other cases of standardisation. We attach to By's copy of this memo a copy of these tests. They are arranged to include such abnormal conditions of working as will, in our judgment, render the satisfactory passage through them of any coil, an indication of the suitability of that type of coil for standard. In the meanwhile our recommended specification involving the least risk of failure in the present circumstances is as follows :- Core as standard. Core insulation 2 turns of .006 oil silk 2.875 wide. | ||