GB322670A - Improvements in or relating to electric lamp fittings - Google Patents

Abstract

322,670. Revo Electric Co., Ltd., and Reeves, F. H. Jan. 3, 1929. Cut-out arrangements. - An explosion-proof lamp for use in mines, petrol stores &c. has an enclosed flame-proof chamber l comprising a cylindrical member a, Fig. 1, and a piston member d slidable therein, opposed contacts r, s being carried by these members and springs o acting upon the piston member to break the lamp circuit within the flame-proof chamber when the lamp reflector f or lamp closure fastenings are released. In a modification, the circuit is also broken on breakage of the lamp globe. The member a has cooling fins c and a broad flange b machined on its under surface against which the reflector f is secured by three studs h. A ring k fixed to the reflector supports the globe i and a flange e on the piston member d rests upon a corresponding internal flange of the reflector. Fixed to the under side of the piston member is the lamp-holder t. The springs o surround pins p screwed into the top of the member a and passing freely through the bottom of the piston member d and through the insulating blocks m, n carrying the contacts, which are provided with terminals for the electric leads. On release of the studs h the piston member d is forced downwardly by the springs, breaking the circuit, the movement being limited bv stops q on the pins p. The contacts r, s are hermetically sealed by a sealing compound. In Fig. 2 the flame-proof chamber 20 is constituted between a hollow piston member 9 in which is sealed the lamp-holder 11, and an insulating plate 6 through which pass terminal stems 4. Fixed to the piston is a wire loop 14 adapted to bear against the lower inner face of the globe 16, and the piston member is pressed downwardly by springs. The globe is carried by a ring 17 fixed to the body 1 by studs 18. On release of the studs 18 or breakage of the globe the piston member is forced downwardly so that the spring contacts 12 of the lampholder leave the terminal stems 4, the movement being limited by ring 10. The plate 6 and lampholder are sealed by sulphur cement.