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).
Troubleshooting dynamo charging issues on Post War Cars, specifically regarding the cutting-in speed.
| Identifier | ExFiles\Box 36\4\ scan 152 | |
| Date | 7th October 1920 | |
| J.S. RECEIVED OCT 18 1920 Oy2 - G 71020 Oct. 7, 1920 Mr. Claude Johnson, Managing Director, Rolls-Royce Ltd., London, England. Dear Sir:- X.30146 Re: New Chassis Troubles Electrical Outfit on Post War Cars X.376 X.294 Under date of September 28th Mr. Hulley makes the following report: "Further to our conversation on the dynamo not charging until the car is running at a fairly high speed, we had a case of this come in this morning. Chassis 8-PP came in to have the speedometer cable looked over and I found upon giving the car a trial run down the road that the dynamo did not charge until the car was going at 23 miles an hour. First of all we took the driving belt off and found that the sides of the links were shiny and very hard. We roughened these up with the edge of a file and tried it again and got the charging to take place at 18 miles an hour. This not being good enough, we took the dust cover off the rear of the dynamo and retarded the third brush nearly 1/4". This had the desired effect of bringing the cutting-in speed down to 15 miles an hour. Every chauffeur I have talked to tells me that although the dynamo will charge at a respectable speed while the car is cool, it invariably goes off when everything gets warm. X.3735 I have wondered if the heat in the pan coupled with oil which may be about has anything to do with hardening the drive belt. Also could we notice if after a long run 22-LW charges at a different speed than when cold, 22-LW has 1/2" link belt fitted and I think the smaller links should offer more surface friction. Fifteen miles an hour, anyway, is apparently the best and lowest cutting-in speed that can be obtained with the present outfit. [Stamped across document: COPY] | ||