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).
The failure of the ballast resistance in the chassis battery ignition system, its cause, and a proposed modification.
| Identifier | ExFiles\Box 46\3\ Scan169 | |
| Date | 9th December 1920 | |
| X.3716 By.{R.W. Bailey - Chief Engineer} From Mr. [REDACTED] (Clerk-in-Charge, Brock) C. to EFC. EP{G. Eric Platford - Chief Quality Engineer}21/M9.12.20. A.T. X.3716 RE. CHASSIS BATTERY IGNITION - FAILURE OF BALLAST RESISTANCE. We have had a few failures on cars on test and cars in service, of the ballast resistance, owing to imperfect contact between the head of the bolt of the external terminal and the internal spider spring which makes contact to the actual ballast resistance. This faulty condition appears to have been caused by some substance from the micanite (shellac?) getting in between these two surfaces whilst the ballast resistance is in a hot condition. We now appear to have replaced this micanite with mica, without shellac, with which we have had no trouble in this respect, although this has not been used for very long. This was done owing to previous experience we had of the above failure. A sample of the fault as above described has been sent to Mr. Brock. We are now concerned with this failure taking place on cars in service. Although we may point out to them this weakness so that they can correct same in case it occurs, we would like to instruct that some modification can be made to the ballast resistance so that this fault does not so readily occur. We would like to propose that a spring washer be fixed between the nut and the brass washer which holds the bolt in position through the case. We should like your confirmation of this, or some such device about which we can circulate our Depots accordingly, unless it is desired that we should replace all the micanite with mica. We shall of course require an order number, or instructions that this will have to be charged to R.D.D. EP.{G. Eric Platford - Chief Quality Engineer} R.R. 199 (3501) (SD676 10-7-17) M/P 18086 | ||