Electricity: circuit makers and breakers – Liquid contact – Time delay
Patent
1978-03-30
1979-04-10
Hall, George T.
Electricity: circuit makers and breakers
Liquid contact
Time delay
200 67R, 200302, 179 18GC, H01H 116, H01H 332, H01H 902
Patent
active
041490525
ABSTRACT:
An electric power tool mounted switch that provides safety-disconnect under contact-weld conditions, and is of the manual close, manual open, or momentary (spring return), double-pole type having an actuator of the toggle lever, trigger or other suitable type. The operating member actuates one end of an intermediate lever normally pivoted at its other end on a slidable safety-disconnect bar that is normally held to the base by a first spring-loaded detent. The intermediate lever is coupled and pivotally mounted at its midportion to a slidable contact carrier through a firing spring and positive action mechanism. The contact carrier slides along and is held to the safety-disconnect bar by a second spring-loaded detent in either its contacts closed or contacts open position. In normal operation, upon movement of the actuator to "on", one firing spring is compressed and follow-up positive action causes the second detent to release allowing the contact carrier to snap over and close the contacts, and similarly to reopen the contacts under manual control or momentary return spring force and the other firing spring and follow-up positive action. Should one or more contacts weld closed so that the contact carrier cannot return, the intermediate lever compresses the other firing spring whereupon follow-up positive action releases the first detent allowing the safety-disconnect bar to trip and snap over and force out a component such as a kick-out spring on a stationary contact that causes the circuit to open. This helical, compressed, kick-out spring normally holds a close-first open-last leaf spring stationary contact against one movable contact but when kicked out, allows the stationary contact to flex open under its inherent bias thereby to interrupt the power circuit to the tool.
REFERENCES:
patent: 1589922 (1926-06-01), Anderson
patent: 3035134 (1962-05-01), Hults
patent: 3047682 (1962-07-01), Hults
patent: 3953697 (1976-04-01), Teichert
Cutler-Hammer, Inc.
Hall George T.
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