US 5,237,302 AGranted

Fail safe switch

AssigneeKransco

InventorTimothy S. Harris

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Abstract

A free-wheeling safety switch is intended for controlling a power supply for a motor and includes a linked single-throw conductor and a double-throw conductor. A fusible link is located between the poles of the conductors. A connection between the double-throw conductor and the single-throw conductor switches the conductors sequentially such that the double-throw conductor switches between its normally closed position and its switched position prior to the single-throw conductor shifting from its normally-off position to its on position. The single-throw conductor is switched from its on position to its off position before the double throw conductor switches to its normally closed position. The power supply is electrically connected to the motor only when the double-throw conductor is in its switched position and the single-throw conductor is in its on position.

Claims10

Dependent claims

A free-wheeling safety switch for controlling a power supply for a motor, comprising:

a double-throw conductor, having a center pole, a first, normally-closed contact, and a second, normally-open contact, wherein the double-throw conductor is switchable from a normally closed position to a switched position wherein the first contact is open and the second contact is closed;
a single-throw conductor having a pole and a contact which is switchable between a normally-off position and an on position;
a fusible link located between the center pole and the single throw pole;
and
a connection between the double-throw conductor and the single-throw conductor which switches the conductors sequentially such that the double-throw conductor switches between its normally closed position and its switched position prior to the single-throw conductor shifting from its normally-off position to its on position, and wherein the single-throw conductor is switched from its on position to its off position before the double throw conductor switches to its normally closed position;
wherein the power supply is electrically connected to the motor only when the double-throw conductor is in its switched position and the single-throw conductor is in its on position.

3 more elements

A free-wheeling safety switch for electrically connecting a power supply to a motor, comprising:

a double-throw conductor, having a center pole, a first, normally-closed contact, and a second, normally-open contact, wherein the double-throw conductor is switchable from a normally closed position to a switched position wherein the first contact is open and the second contact is closed;
a single-throw conductor having a pole and a contact which is switchable between a normally-off position and an on position;
a fusible link located between the center pole and the single throw pole;
and
a connection between the double-throw conductor and the single-throw conductor which switches the conductors sequentially such that the double-throw conductor switches between its normally closed position and its switched position prior to the single-throw conductor shifting from its normally-off position to its on position, and wherein the single-throw conductor is switched from its on position to its off position before the double throw conductor switches to its normally closed position, and wherein the power supply is electrically connected to the motor only when the double-throw conductor is in its switched position and the single-throw conductor is in its on position.

2 more elements

Dependencies are inferred from the claim text.