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 Sparking Plug Co. Ltd. discussing welding problems with spark plug screen extensions.
| Identifier | ExFiles\Box 163\5\ img055 | |
| Date | 3rd September 1936 | |
| TELEGRAMS: SPHINX, DUNSTABLE TELEPHONE: DUNSTABLE 360 PRIVATE BRANCH EXCHANGE. 86011 THE AC-SPHINX SPARKING PLUG Co. LTD. DIRECTORS: N. F.{Mr Friese} STOCKBRIDGE, W. O.{Mr Oldham} KENNINGTON. C. J.{Mr Johnson W.M.} BARTLETT. DUNSTABLE BEDFORDSHIRE OUR REF. NFS/GEB. YOUR REF. Hs{Lord Ernest Hives - Chair}/Wst.3/JH. 3rd September, 1936. Messrs. Rolls-Royce Limited, Derby. For the Attention of Mr. H.{Arthur M. Hanbury - Head Complaints} E.{Mr Elliott - Chief Engineer} West. Dear Mr. West, I was disappointed to note from your letter of yesterday to hand this morning that the welding of the screen extensions on plugs types X410 and X412 is not satisfactory. The difficulty is unfortunately not easy of solution. Firstly, in order to preserve the real heat-flow advantages inherent in the one-piece (non-detachable) design of plug, I am opposed to attempting a solution by means of a detachable design. We were rather forced in our design into the idea of welding on the screen, due to the size of hexagon and the length of the plug body beneath the hexagon, which you claim you must have to get the plug into your engine. If the welding of the screen extension is unsatisfactory, an alternative lies in screwing this on to the plug body, as shown in view A on our drawing X412(a) herewith, but, as you will see and understand, this forces us on to a larger hexagon as well as a shorter length of body beneath the hexagon. Provided you can give us a plug pocket large enough to take this plug as in design A, this would seem to be satisfactory. If you will look into the matter and confirm that the design A presents no difficulties as far as space is concerned, I will have the two sets of plugs modified accordingly and get them away to you as soon as possible. Unfortunately I cannot adopt the suggestion in the second paragraph of your letter, i.e., of making the welding more substantial around the top metal roll-over, as this is likely to affect the gas tightness of the plug. MAKERS OF AC SPARKING PLUGS - AC AIR CLEANERS - AC PETROL PUMPS - AC PETROL GAUGES - AC OIL FILTERS - AC OIL GAUGES | ||