GB299412A - Improvements in or relating to sparking-plugs - Google Patents

Abstract

299,412. Guinness, K.. E. L. July 25, 1927. Divided on 284,391. Sparking-plugs.-The central conductor 16 may be replaced by another having the part 30 of a different size whereby the volume of the chamber at the inner end of the plug may be altered. A steel bush 12 encloses the conductor 16 and is insulated from the casing by mica wrapping and washers. Lateral pressure is applied to the casing to effect a permanent union of the casing, mica wrapping and steel bush. At its outer end the bush has a hexagonal flange 13 which is gripped when the conductor 16 is to be removed thus avoiding stress on the insulation during this operation. Betwen the hexagonal portions 19, 13 on the conductor and bush respectively, the former may be reduced in diameter. The application of excessive force will thus result in the fracturing of the conductor before damage can be done to the insulation. The outer part of the conductor may be separate from the inner, the two being connected by a screwed extension and socket as shown in Fig. 1. The threaded extension on the main portion may however enter a plain hole in the outer portion in which case the latter is formed with a threaded recess at its outer end. When the part 16 has to be removed, the outer part 26 is reversed and the threaded members brought into positive engagement. Specification 284,391 is referred to.