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).
Investigation and comparison of an American Bosch ignition coil against the company's own standard coils.
| Identifier | WestWitteringFiles\P\October1926-November1926\ Scan086 | |
| Date | 8th November 1926 | |
| To R.{Sir Henry Royce} from EFC. c. BJ. Wor.{Arthur Wormald - General Works Manager} c. Oy. By.{R.W. Bailey - Chief Engineer} c. Rg.{Mr Rowledge} ORIGINAL AMERICAN BOSCH BATTERY IGNITION EQUIPMENT. Further to our EFC3/T25.10.26, we have now investigated the quantities of the coil of one of the ignition coil sets sent to us by OY. and attached please find copy of my assistant's report WB.{Mr Brazier/Mr Bell}109 in this connection. A comparison of the resistance (primary, excluding and ballast),/inductance of our previous standard coil, our new finer primary standard coil, and this Bosch coil is contained in the table below :- Resistance. (ohms). Approx.Inductance. (henries). Old Std. 1.18 .010 Finer primary. 1.90 .015 Bosch. 1.17 .006 from which it will be seen that the Bosch has both a lower resistance and a lower inductance than either of our own coils. The coil is intended for 6 volt running direct without a ballast resistance and presumably they would supply a ballast resistance for 12 volt operation. Later on we hope to be able to give a comparison of the current at 6 volts at a speed corresponding to 30 m.p.h. with our own current at 12 volts. EFC. | ||