GB1052256A - - Google Patents

Abstract

1,052,256. Switches held set and freed mechanically. ROWAN CONTROLLER CO. Sept. 24, 1963 [Oct. 1, 1962], No. 37567/63. Heading H2B. A push-button switch incorporates a fuse in the main circuit and auxiliary contacts to light an indicator lamp housed in the button. A body 16 has a plunger 21 slidable therein and a fuse 45 is mounted in the plunger 21 by means of a resilient U-shaped conductive strip 66 such that one end 44 can be pressed against a contact 43 on a spring blade 42 to complete a circuit between terminals 24 and 26, the terminal 24 being connected to a conductive ring 40 which is engaged by the ends of the U-shaped strip 66 when the plunger 21 is depressed. A lamp is located in plunger 21 (Figs. 5 and 7, not shown), so as to be visible through end 23 and is connected to contact members 77 and 78, respectively engaged by plunger-type contacts 48 when button 21 is pushed in (Fig. 4, not shown). One contact 48 is connected directly to terminal 25 while the other contact 48 is connected to terminal 27 via a resistor 52. The terminals 24, 25, 26 and 27 are retained in position by shoulders 30 thereon engaged by the end cover 17 which has a lip 37 mating with a flange 36 on casing 16. In the " off " position the contacts 48 engage in L-shaped grooves 87 in the plunger 21 and limit the outwards movement of the plunger, but if the plunger 21 is then rotated ramps 90 lift the contacts 48 so that the plunger 21 may be withdrawn from casing 16 in order to replace the fuse 45. A key 63 on plunger 21 must be aligned with a keyway 64 before the plunger can be moved into the " on " position and serves to prevent inadvertent operation of the switch when not so aligned. The plunger is retained in the depressed condition (Fig. 4, not shown), against the spring blade 42 by a combination of friction of the ends of strip 66 against ring 40 and the ends of plungers 48 against a slight shoulder of the recess 75 in which contacts 77 and 78 are fitted.