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).
Experiments with double value ballast resistances for ignition circuits to improve platinum point life.
| Identifier | ExFiles\Box 168a\5\ img020 | |
| Date | 1st September 1927 | |
| To R.{Sir Henry Royce} from EFC. c. PJ. Wor.{Arthur Wormald - General Works Manager} c. E.{Mr Elliott - Chief Engineer} BY.{R.W. Bailey - Chief Engineer} c. Da.{Bernard Day - Chassis Design} X8720 EFC5/T1.9.27. DOUBLE VALUE BALLAST RESISTANCE. Several times we have referred to the fact that we have been experimenting with double value ballast resistances for the ignition circuit, largely with a view to reducing the amount of current taken by the ignition circuit from the point of view of better behaviour of the platinum points. Three such units have completed 10,000 miles running on experimental chassis 10-G3, 11-G3, and 8-EX. These ballast resistances did not cause any irregularity whatever during these tests. Observations were made on the condition of the platinum points on chassis 8-EX and 11-G3. These appear to indicate that the reduction of primary current due to the use of the higher resistance had resulted in improved functioning, and therefore life, of these points. On 8-EX particularly the points functioned very well, only one trimming being necessary at 7000 miles. These points were sent to you under cover of our EFC1/T26.8.27. On 11-G3, superficial trimming was necessary at 4,000 miles and again at 6,000 miles. Although these platinum point performances are not ideal, they are considered to be better than those obtained under normal standard conditions. Owing to the fact that other conditions on the electrical circuit were reasonably normal, e.g. normal voltage always available, it was considered that further special tests of such ballast resistances on chassis on the road were necessary. Two such tests have been carried out on 12-EX and 11-G3. Contd. | ||