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).
Recommended modifications for a new universal standard ignition coil following laboratory testing.
| Identifier | ExFiles\Box 164\5\ img170 | |
| Date | 4th April 1933 | |
| 86017 To E.{Mr Elliott - Chief Engineer} From Hs{Lord Ernest Hives - Chair}/Wst. c. By.{R.W. Bailey - Chief Engineer} By/RD. NEW TYPE UNIVERSAL STANDARD IGNITION COIL FOR ALL CHASSIS. As a result of laboratory tests on the new type R.R. ignition coil with outside primary winding we recommend the following modifications :- (1) The paper insulation between the first two and the last two layers of the secondary winding should be reinforced against surges. We suggest three turns of paper instead of two between these layers. (2) A direct breakdown occurred between the primary terminal and the H.T. insert through the terminal bakelite moulding. We have already suggested to By/RD. that modification to this moulding is necessary. (3) Inductance measurements and heating tests shew that the iron circuit requires modification. The slotted iron sheath should be of "Stalloy" and should extend the whole length of the coil - i.e. from the top edge of D.73611 to the bottom edge of D.73612. This will ensure that no flux changes occur in the metal case, as is the case at present. In order to reduce the bulk of the core and incidentally reduce costs we suggest that tube D.73501 be deleted and the diameter of D.73502 reduced accordingly. There is no objection, so far as we can see, in the iron core itself, being at high potential, it is in any case electrostatically. We should like to see the iron core produced more simply with "Stalloy" strips without any wires. The extra reluctance is we consider more than compensated by the use of the external iron sheath. We are sending you the core from a Bosch coil for your inspection. It is important that the thickness of the pedestal insulator D.73612, or the distance from the base of the iron core to the base of the metal case, be increased, in order to prevent flux passing through the iron case, and we suggest lengthening the | ||