GB544435A - Electrical liquid-contact switches - Google Patents

Abstract

544,435. Mercury switches. O'BRIEN, J. F. Oct. 9, 1940, No. 15051. Convention date, Oct. 26, 1939. [Class 38 (v)] A mercury switch is rotated in steps, in one direction by manual operation through gearing connected to a reciprocating plate, there also being means for determining the degree of rotation at-each operation. In the example, a push button 10, or pull chain, operates a bellcrank lever 39, the other arm of which slides back a plate 35 against the pressure of a spring 38, pulling, through a' lost-motion connection, 35a, 34b, a hooked drag-link 34 to move one of four studs 33 on a gear wheel 31 meshing with another 23, in a ratio of two to one, secured to a rotary mercury switch 21. Unless the pull is sufficient to take a stud past the pointed end 35b of the plate, on release of the button &c. the return of the plate will return the mercury unit. The unit 21 is of the type having two metal cups 21a, 21b joined at their edges by an' insulating disc 21c with an aperture 21<SP>1</SP> enabling mercury on the two sides to make contact. One cup 21a is driven through a locating feather 21e on metal seating aid secured to a stud 22 spring - pressed by a contact blade 24 on a conductor 25. The other cup 21b rotates on a pressed-out button 26<SP>1</SP> on a yoke 26, the arm 27<SP>1</SP> of which is wedged in a spring clip 28 on the other conductor 29. The casing lid 11d may have a window through which an indicator lamp 14 can be seen. Preferably this is a neon lamp and the mounting and connecting parts 46, 47 are arranged that either electrode can be brought near to the window by rotating the lamp. Lugs from these parts engage spring clips on the conductor wires such as 29, embedded in the casing, when the switch is used with sectional conductor wiring.