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).
General inferences from tests on various coil case materials, comparing their performance under heat.
| Identifier | ExFiles\Box 39\3\ Scan271 | |
| Date | 16th September 1926 | |
| Contd. -7- EFC1/T16.9.26. The samples L and O were tested at 100°C, the other two were merely heated by the electrodes from a previous test, when a preliminary reading shewed them to be too bad for test at the full temperature. General Inferences. The tests on the redmanol coil cases and on some of the sheet material all concur that increased leakage accompanies increased temperature. The stabalite case remained almost leakless, however, right up to the full temperature. (It became somewhat softened at 100°C). The cases and sheet material tend to shew, but not quite consistently, that repeated heating and cooling improves the insulation and this is particularly confirmed by the coil case taken from a car, which gave the best result of any. Of the sheet material, the brown grades in every case were bad, while the best results were obtained with the yellow linen-based material and the Mosses & Mitchell grade "O" after heating and cooling. Some of the original faulty short type ignition coils are being tried for ignition characteirsites on the bench at temperature, and if these now still shew the original characteristics they will also be re-tested in the above manner. EFC. | ||