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 investigation of failures in 20 HP ignition coils and experiments with improved designs.
| Identifier | ExFiles\Box 45\4\ Scan172 | |
| Date | 17th July 1923 | |
| X4079 To EP.{G. Eric Platford - Chief Quality Engineer} from EFC. c. Hy.{Tom Haldenby - Plant Engineer} c. Wor.{Arthur Wormald - General Works Manager} c. Sft.{Mr Swift} for Mr. Brock. EFC1/T17.7.23. X.4079 - 20 H.P. IGNITION COILS. X4273 Further to our EFC2/T16.7.23, coil No.2963, in which there existed a definite break in the primary winding, has now been handed to Mr. Gamble and dismantled for examination. It has been found that in one of the connections inside,the solder had not properly run, and the action of temperature had apparently made the wire end break away from contact. will To prevent this occurring again still more care should be exercised in the inspection of these soldered joints. The repetition of this defect is extremely unlikely. Further investigations are being carried out on coils Nos.2960 and 3009, but so far it appears that the failure in each case is due to something having happened to the primary winding and is in no way similar to the failures which we obtain on mouldensite encased coils, due to the effect of temperature on the casing material. Regarding the ignition coil position generally, we all of us know that the primary winding of the 40/50 ignition coil is somewhat liable to failure for reasons of getting in the necessary secondary winding and insulation with the 6-layer primary winding which is required, and that cases of such failure have occurred previously on 40/50 cars. No drastic step to remove this source of failure has been so far taken, because we have for some time been working on Goshawk ignition coils and particularly latterly on the 1/2" longer coils, and it was agreed that when these coils were right they should be adopted on the 40/50 in addition to the 20 H.P. We have had Mr. Royce's agreement (R6/M29.1.23) in answer to our EFC2/T29.1.23, which see, to all further experimental work being carried out on coils 1/2" longer, and a number of coils thus lengthened have been made and run on experimental cars, some of these in the new wheelcase position. Unfortunately, however, even these coils do not appear to have entirely overcome the possibility of failure, due to material, and that fact has naturally put back the standardisation of these lengthened coils, which in other respects (e.g. 4-layer primary winding) are a decided improvement over the present 40/50 stabalite coils. Further experiments are accordingly in progress with various other materials and we have one coil made up with | ||