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).
Clarifying a misunderstanding about the number of turns in an ignition coil's secondary winding.
| Identifier | ExFiles\Box 164\5\ img148 | |
| Date | 16th April 1932 | |
| X6045 By.{R.W. Bailey - Chief Engineer} From Hs{Lord Ernest Hives - Chair}/Wst. c. to By/Rd. Hs{Lord Ernest Hives - Chair}/Wst.2/MA.16.4.32. PRESENT STANDARD IGNITION COIL WITH THINNER SECONDARY WIRE AND INCREASED NUMBER OF SECONDARY TURNS. It appears there has been a little misunderstanding with regard to the number of secondary turns for the above coil. In the first instance Mr. Davis instructed some coils to be made up with 20,000 turns of 44 SWG wire. When Mr. Brock produced these however he put on 21,000 turns as he found he could do this quite easily without increasing the diameter of the coil above the old standard. We agreed to this but unfortunately omitted to inform you at the time, consequently our standardisation sheet refers to a coil having a 21,000 secondary turns, whereas the present instructions to the production department on drawing D.72503 are 20,000 turns as originally instructed. As all our standard tests were carried out on coils having 21,000 turns secondary winding we should be glad if you will arrange to alter the drawing and instruct Mr. Brock accordingly so that the correct number of secondary turns can be put on the coils. Hs{Lord Ernest Hives - Chair}/Wst. | ||