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Publication numberUS1108350 A
Publication typeGrant
Publication date25 Aug 1914
Filing date2 Dec 1913
Priority date2 Dec 1913
Publication numberUS 1108350 A, US 1108350A, US-A-1108350, US1108350 A, US1108350A
InventorsFritz Faerber
Original AssigneeFritz Faerber
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Electric conductor.
US 1108350 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)




1,1 08,350, Patented Aug. 25, 1914 HE NORRIS PETERS 60.. PHOTO-LIIHOY, WASHINGTON. D C.

rnrrz rltnsnra, or DOR'IMUND, GERMANY.


Specification of Letters Patent.

Application filed December 2, 1913.

Patented Aug. 25, 1914. Serial No. 804,275.

, ject of the King of Prussia, German Emperor, and resident of Dortmund, in the Kingdom of Prussia, German Empire, have invented an Improved and Novel Electric Conductor, of which the following is a specification.

The electric safety lamps hitherto employed in mines or other dangerous industrial works are generally constructed in such a way that the accumulator and the incandescence lamp are united in a solid casing. There is, however, a need in some industrial works to have the lamp proper and the ac- 3 cumulator separated one from the other,

both parts being then electrically connected by a flexible cord, but this arrangement has the drawback that in the case of an injury to that cord short-circuiting may occur which then may give rise to an explosion if an explosive gas or gas mixture is present. Such a danger isobviated by my present invention, one form of execution of which is illustrated as an example in the accompanying drawing, in which a is an electric accumulator, 0 the incandescence lamp proper, and Z) a flexible cord connecting the parts a and 0 with each other.

lhe gist of the invention now resides in using as conducting metal in the cord a metal the fusing point of which is very low, such, for instance, as load or tin. It by any cause a short-circuit is produced in the cord, for instance by one or the cord wires tearing or breaking, and piercing the insulating covering and coming in contact with the other wire so as to produce a short-circuit, then this latter will fuse the wire metal, but no explosion will occur, because the fusing temperature amounts to about 400 C. only, whereas the ignition temperature of the explosive gas or gas mixture is considerably higher, 2'. 6. about 700 C, In the case of copper, however, an explosion would take place, as the fusing temperature of copper lies considerably above 700 C. and thus white-heat already would ignite the explosive gas or gas mixture.

Electric circuits in which one ofthe con ductors is made of an easily fusible metal have already become known, it is true, but they in general and the easily fusible conductor in particular termed a part of a fire alarm plant operated with constant current, andthe object was to interrupt this current and actuate thus the alarm mechanism ii. that conductor got fused in the case of a fire. Thus, although the means 7961" as is already known, still, it is employed in the present case in a novel combination and for a novel purpose, viz. in combination with safety lamps and for the purpose of interrupting the current in the case oi a short-circuit by letting the conductor metal be fused at a r temperature which doesnot rise to the ignition temperature oi. the gas or gas mixture surrounding the lamp.

The sparks arising on opening a circuit operating with a current of from 2 to 4 volts, as generally used in connection with lamps of the kind in question, do not ignite a gas or gas mixture elf the kind in question, and therefore it the connecting cbrd should get torn this will. not bring about an ignition of the explosive Connecting cords orconductors 01 this kind, as before described, may thus be regarded eXplosion-proof.

Having now described my invention, what I desire to secure by a Patent of the United Fitates isf l The combination, with a battery and an electric safety lamp, of connecting conductors consisting elf a metal the fusing point of which lies below the ignition tern as that may be perature of an explosive said lamp, tor

present inthe space around the purpose as described. a p

In testimony whereoi I aflii: my signature in presence of two witnesses.


[n s] Witnesses:


Copies of this patent may be obtained for live cents each, by addressing the Commissioner of Patents,

Washington, D. 0." a

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US5154483 *9 Aug 199113 Oct 1992Zeller Noel EFlashlight with flexible extension
US5517392 *5 Aug 199414 May 1996Black & Decker Inc.Sleeve retention for flexible core of a flashlight
US5521803 *5 Aug 199428 May 1996Eckert; Lee H.Flashlight with flexible core
US20040174703 *4 Mar 20039 Sep 2004Lisle CorporationFlexible flashlight with LED light source
U.S. Classification362/198, 362/21
International ClassificationF21L4/06, F21V25/12
Cooperative ClassificationF21L4/06, F21V25/12, F21V21/0824
European ClassificationF21V21/08S, F21V25/12, F21L4/06