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 investigating chassis sparking and tracking in the 20 HP engine distributor head.
| Identifier | WestWitteringFiles\N\July1925-September1925\ Scan59 | |
| Date | 2nd August 1925 | |
| Contd. -2- 1 EPC2/T1.2.8.25. head. There is also a report EPC2/T18.9.23 of experiments to determine if, in any circumstances of running on 20 HP. chassis sparking will occur in the battery ignition distributor head. This was found to be possibly only in the very extreme conditions, such as would be very unlikely to occur on a car in service. It is known, however, that once it is possible, so soon as conditions arise in which sparking must take place on what is the supposed safety gap of the distributor, that this sparking will cause tracking and that the distributor head will be rendered useless for ordinary working. In other words, the supposed safety gap is nearly useless because the sparking will not occur direct from metal to metal, but will, as we know, track along the surface. This is the possibility that ought to be eliminated. Two distributor heads in which this phenomenon of tracking has occurred on experimental 20 HP. engines are being sent to R.{Sir Henry Royce} for his inspection (under separate cover). EPC. | ||