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).
Failure of an ignition coil due to a loosening fixing stud for the ballast resistance.
| Identifier | ExFiles\Box 46\3\ Scan186 | |
| Date | 18th March 1920 | |
| X.3445 BY.{R.W. Bailey - Chief Engineer} from EP.{G. Eric Platford - Chief Quality Engineer} c. to Ck.{Mr Clark} EP{G. Eric Platford - Chief Quality Engineer}5/F18.3.20. A.T. X.3445 RE. FAILURE OF IGNITION COIL ON 3-PP. X.3716 I have noted yours BY8/F16.3.20 and am quite prepared to agree that the cause of this failure is No.(1) point suggested in your memo., as it is certainly a fact that the fixing stud for this ballast resistance becomes slack when the coil has been in service for some time, as already explained in my previous memo. EP{G. Eric Platford - Chief Quality Engineer}4/F16.3.20. It would appear, therefore, that the design is defective in this respect, and I should be glad if this complaint could receive your consideration, as I can quite appreciate that if this ballast resistance is cut out, the coil will soon burn itself out if it is left on for a short time. We will take action to see that this point is carefully inspected so that as far as possible this failure can be prevented, but owing to the fact that this stud is affected by the expansion and contraction of the insulation, I do not think we can guarantee eliminating the possibility of a similar failure occurring again. With regard to the overheating of the coil caused by leaving the ignition switch on, I was pleased to note results of Ck{Mr Clark}'s tests reported in Ck{Mr Clark}1/T15.3.20 and Ck{Mr Clark}4/T15.3.20. It must be realised that the heat from this coil may be taken advantage of by the customer to avoid engine freezing up in cold weather, in fact having decided to separate the ballast resistance from the coil, some ingenious driver will suggest fixing it in a suitable place to get the best out of it for this purpose. EP.{G. Eric Platford - Chief Quality Engineer} | ||