GB584631A - Improvements in or relating to transformer structures - Google Patents

Abstract

584.631. Snap-action switches; actuation of switches. BRITISH THOMSON-HOUSTON CO., Ltd. Jan. 11, 1945, No. 925. Convention date, Jan. 11, 1944. [Class 38 (v)] The operating mechanism of a snap-action limit switch, the contact structure and latching means of which may be similar to those disclosed in Specification 565,450, comprises a substantially cylindrical operating member 46 mounted within the switch casing and rotating with a shaft 47, an actuating member 40 pivoted at 42 for rotation between two limiting circuit-controlling positions, and a clutch arm 44 attached to the member 40 and extending into releasable clutching engagement with the member 46 so as to connect the members 40 and 46 over a predetermined range of rotation of the member 46 and to disconnect them in the case of overtravel. The member 40 actuates the latching means in the manner disclosed in the above-mentioned Specification. The arm 44 has a spring-pressed ball 45 engaging a groove 48 in the member 46, which has an integral radial arm held between the ends of a strong spring 52. A stop member 53 mounted on a partition within the casing, has two dogs 54 which are also held between the ends of the spring 52 and which hold one end of the spring when the member 46 is rotated, thereby stressing the spring. Contact 20, normally bridging contacts 18, is moved to bridge contacts 19 by counter-clockwise rotation of member 46, which movement causes member 40 to move counter - clockwise about pivot 42 through the clutching arrangement 44, 48. This movement of member 40 reverses the positions of the latch members 28, 29, 30, and causes the contacts 20 to engage contacts 19. Should the member 46 continue to rotate, the ball 45 rides out of groove 48 and the member 46 is stopped by the engagement of a shoulder 50 with the casing. Release of the handle 46 causes the parts to return to the normal position shown. This normal position may be changed by sliding stop member 53 downwards on the casing so that the member 46 is moved counter-clockwise and the position of the member 40 is reversed so that it engages the right-hand end of lever 28. The casing is ventilated through a vent in the cover.