US1361684A

US1361684A - Safety switch-box

Info

Publication number: US1361684A
Authority: US
Publication date: 1920-12-07
Anticipated expiration: 1937-12-07

Description

'Huf WW" E. M. COFFIN.

SAFETY SWITCH BOX. APPLICATION FILED FEB. 25, 1918.

Patented Dec. 7, 1920.-

UNITED STATES PATENT OFFICE.

EVERETT M. COFFIN, 0F PIEDMONT, CALIFORNIA.

SAFETY SWITCH-BOX.

Specification of Letters Patent.

Patented Dec. '7, 1920.

Application filed February 25, 1918. Serial No. 218,926.

To all whom it may concern:

Be it known that I, EVERETT M. COFFIN, a citizen of the United States, residing at Piedmont, in the county of Alameda and State of California, have invented new and useful Improvements in Safety Switcha horizontal section thereof on the line 2 2 of Fig. 1; Fig. 3 is a vertical section on the line 33 of Fig. 1 looking in the direction of the arrow; Fig. 4: is a similar section on the line 4l4l of Fig. 1.

Referring to the drawing, 1 indicates a knife switch mounted upon an insulating base 2 and inclosed in a box-like receptacle 3. Said switch is operated by means of a link 4: secured at one end to the insulating yoke 6 of the switch and at the other end to a U-crank arm 7 having bearings in the sides of the receptacle and extended through one of said sides to form a crank handle 8 by which the crank arm can be turned in its hearings to open and close the switch, so that it is not necessary for this purpose to open the receptacle. The lid 9 of the receptacle is hinged to one side thereof, as shown at 11, and has a knob or handle 12 for opening and closing it. It is provided with a keeper 13 extending inwardly from the lid, about opposite to said knob, which is engaged by a spring-actuated latch 14 pivoted on the adjacent side of the recep,

tacle and the movement of which is limited,

by the guide 25, said keeper having two notches 16 either of which can be engaged by said latch. Secured to the inner side of said lid, near its hinged edge, is a stop plate 17 which extends from said lid in a plane transverse to the line of the hinges and in the form of a sector of a circle somewhat greater than a quadrant. This stop plate can move through an open-ended slot or recess 15 extending inwardly from the free edge of the side of the receptacle to which the lid is hinged. Thestop plate extends from said lid in such a direction that, when the lid is down, or, in other words when the receptacle is closed, the crank arm 7 can just pass the edge 30 of the stop plate 17, but, if the lid is raised to any extent, the stop plate swings into a position such that said edge 30 advances into the path of the crank arm 7 tending to close the switch, and prevent the same from being closed.

In Fig. 4 thelid is shown as closed and i one of the notches 16 engaged by the latch 14-. The other notch 16 is engaged by the latch 14 when the lid is not quite closed, but is closed sufiiciently to permit the arm 7 topass the stop plate 17. But for the provision of this second notch the object of the invention might be defeated by the 0perator nearly, but not quite, closing the box and then closing the switch, in which case access could be had to the closed switch by merely raisin the lid of the box, said lid not then being locked. 7

Attached to said latch 14: is a finger 18, which is engaged by the arm 7 only when the switch 1 is fully opened, thereby withdrawing the latch 14 and allowing the lid 9 to be raised. I

It will be seen that, with the above described construction, the switch box cannot be opened until. the switch is opened wide and the switch cannot be fully opened unless the switch box is fully closed. I

I claim:

In a safety switch box, the combination with a knife switch, of a box-like receptacle for containing the same, a crank arm operatively connected to said switch and having an operating handle extending outside the box, a pivoted lidfor closing the box, a'keeper secured to the lid, a latch engaging said keeper for retaining the lid in a closed position, means moving with the crank arm for withdrawing said latch from its operative position when the switch is opened, and'a stop carried by the lid'and obstructing the movement of the crank arm except when the lid is closed sufficiently to