GB284391A - Improvements in or relating to sparking plugs - Google Patents

Abstract

284,391. Guinness, K. E. L. Oct. 25, 1926. Sparking-plugs.-The central electrode 16 is mounted within a steel bush 12 so as to be readily removable therefrom. The casing 10 and mica lining 11 are compressed about the bush 12, which at its outer end is formed with a hexagonal flange 13. An internal thread receives the outer part 26 of the central conductor, which may merely press the main portion 16 against a flange in the bush 12, or may be combined with such main portion by means of a threaded extension inserted in a recess 27. In the construction in which the part 26 of the electrode. merely presses on the part 16, the withdrawal of the latter may be facilitated by providing a: screwed stem 27 on the part 16, which stem normally lies within an unthreaded recess in the outer part 26. At its outer end the part 26 has a threaded recess which, by reversing the part end for end, may be made to engage the screwed stem on the part 16. Removal of the member 26 is effected by means of the hexagonal portion 19, the transference of any stress to the insulator during such removal being avoided by using spanners on both portions 19, 13. By reducing in thickness the part 20 of the stem below the hexagon 19 this danger to the gas-tightness of the insulator may be further lessened. The inner end of the plug may be fitted either with a screwed ring terminal 22, or with a plain ring over which the end of the casing is turned.