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).
10,000-mile bench tests for battery ignition contact points, detailing tests on condenser values and periodic current reversal.
| Identifier | ExFiles\Box 35\6\ scan 288 | |
| Date | 5th July 1927 | |
| To R.{Sir Henry Royce} from EFC. c. BJ. Wor.{Arthur Wormald - General Works Manager} BX. x2894 EFC2/T5.7.27. X4652 BATTERY IGNITION CONTACT POINTS. x 2894 FURTHER 10,000 MILE BENCH TESTS Ref. previous report LCI/T18.5.27. (14) Double or maximum value condenser. Two cases have been run on the bench :- (a) With condenser of maximum value possible in the condenser case, which is about 63% more capacity than standard. This result is labelled (14) P (a). The conditions of running on this test were otherwise standard, i.e. finer primary coil and present standard (not double) ballast resistance. No trimming was required, but there has been a considerable transference of material from the screw point to the lever point, forming the characteristic hollow and mound. (b) With condenser of double value, i.e. 100% more than standard, as compared with 63% more in the (a) case. (Two standard condensers in parallel actually used). Result labelled (14) P (b). The conditions under which this test was run were not otherwise standard, insomuch as one of the previous standard coils (not finer primary) was used, this being thought to be more appropriate in view of the magnitude of the condenser. The ballast resistance was, however, the same (i.e. standard). In this case also a hollow and pip have formed, the pip having reached to the iron of the screw point. (15) Periodic reversal of current. As requested in your R2/M16.5.27 we arranged a reversing switch to be driven slowly so as to reverse about 4 times per minute, and run a test of platinum points under otherwise standard conditions with this reversal of current. These platinum points are labelled (15), and it will be noted that the condition is entirely satisfactory and far superior to anything else we have had on our own contact breaker. It appears to be such an advantage as to suggest that it is almost worth while to arrange for a reversal of current ignition supply current on the car, which would involve both insulated lever and screw. As a further experiment in this direction, it has been decided to run a standard magneto with one cam lobe removed, so that breaking takes place only on one side, i.e. so that the current at break is uni-directional. It may be expected Contd. | ||