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).
Letter to a customer regarding ignition trouble and the supply of a new coil and ballast resistance for a 20 HP car.
| Identifier | ExFiles\Box 57\2\ Scan016 | |
| Date | 15th May 1929 | |
| X.5783el EFC {E. Fowler Clarke - Electrical Engineer} 2/T. 15th May, 1929. Mr. C.R. N. Minchin, 50 Grosvenor Gardens, LONDON, S.W.1. Dear Mr. Minchin, We have received your letter M {Mr Moon / Mr Moore} /5 of yesterday's date regarding the ignition trouble on your 20 H.P. car. Yes, we do know of this trouble which occurred occasionally first of all on the finer primary coil due to a weakness as a result of overheating, and latterly on the courser primary coil to which we reverted, due to the continued use of the larger ballast resistance which was suited to the finer primary coil. The phenomenon is nothing to do with the condenser or directly with the condition of the contact points. It is only indirectly so because if you lower the contact resistance of the points it just makes sufficient difference to make up for the coil weakness. Latterly the ballast resistance has been slightly lowered to be more suited to the fewer number of primary turns on the coil. Both make the current rather greater, but since we have proved that the life of contact points is not so much a matter of keeping the current down as of the correct mechanical action of the points, this is of no consequence. We are arranging for our Repair Dept. to send you an up-to-date coil and ballast resistance, and I should be pleased if you would be good enough (when you receive these) to have your present coil and ballast resistance returned to us for the attention of our Repair Dept. We wonder if you would be good enough to adopt our suggestion of first changing the ballast resistance only, as this may just make the difference. This may give you complete satisfaction; even if it does, we have no objection | ||