GB1368426A - Electrical switches - Google Patents

Abstract

1368426 Fluid actuation of switches JOSEPH LUCAS (INDUSTRIES) Ltd 7 Sept 1971 [18 Sept 1970] 44606/70 Heading H1N In a fluid pressure switch containing movable contact 18 and fixed contacts 19, 21, fixed contact 19 is resiliently urged against movable contact 18 so that contact 18 first breaks contact with contact 21 then subsequently with contact 19, fluid pressure in chamber 13 acting on diaphragm 17 to depress plunger 16 to depress movable contact 18. Contact 18 is depressed against the action of compression spring 22 bearing on conductive member 28 electrically connected to terminal 27 through stud 31 threaded to adjust the pressure of spring 22 and hence the operating pressure. Contact 19 is part of a sleeve which slides on terminal 25 against the action of a spring, a spring 29 urging contact 19 against movable contact 18, so that as movable contact 18 is depressed it first breaks contact with fixed contact 21 and is followed down by contact 19 until contact 19 can go no further when further depression of contact 18 causes it to break contact with contact 19. In a second embodiment, Figs. 3, 4 (not shown), contact 19 is replaced by a spring blade 32 urged by its own resilience against movable contact 18 to follow it down. In a third embodiment, Figs. 5, 6 (not shown) contact 19 is replaced by a spring arm which follows contact 18 down until the spring arm encounters a stop, which is adjustable to vary the distance travelled by contact 18 before it breaks contact with the spring arm. Reference has been directed by the Comptroller to Specification 1,336,431.