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).
Letter from AC-Sphinx regarding speedometer gearing, a new worm and wheel combination, and disassembly for examination.
| Identifier | ExFiles\Box 165\2\ img144 | |
| Date | 25th November 1937 | |
| 6011 AC-SPHINX SPARKING PLUG Co. LTD. DIRECTORS: N.F.Stockbridge, W.O.Kennington, C.J.Bartlett. Telegrams: SPHINX.DUNSTABLE. DUNSTABLE, BEDS.,ENGLAND. Telephone: DUNSTABLE 360. Our Ref. DBB/DJG Your Ref. Rm{William Robotham - Chief Engineer}/RC.{R. Childs}7/MH.{M. Huckerby} 25th November, 1937. Messrs. Rolls Royce Ltd., DERBY. For the Attention of Mr. B. M.{Mr Moon / Mr Moore} Child. Dear Sirs, With reference to your letter of the 23rd instant referring to the concave dial type instruments which we are making up for you, we have checked into the gearing and we find that by making up one new worm and wheel combination, in the train, we can give you a driving speed of 798, which you will see is less than half of 1% error. During a conversation between the writer and Mr. Davis this morning we had reported that it might not be easy to get down any nearer than the 1,000 revs. per mile without making up a number of new gears, but checking over since the conversation has shown that we shall be able to do it fairly simply, and we therefore propose to make up two or more sets so that we could not only supply this present job, but could change the bevelled glass speedo. now in your possession as soon as you wish. With regard to the speedometer which you wish to have in parts for examination purposes, would you be good enough to inform us to what extent you wish it to be dismantled, as some of the parts are extremely small and you might find some difficulty in checking their correct position unless these are all put into separate packets and some sort of chart made for their position on the actual speedometer. Perhaps you will be good enough to advise us on this point. It is quite understood that the figure of 795 mentioned in your letter applies only to experimental speedometers, and as a matter of fact we have worked out a gear train to suit the AC Air Cleaners · AC Clocks · AC Fuel Pumps · AC Oil Filters · AC Oil Gauges · AC Plugs · AC Speedometers · AC Windscreen Wipers. | ||