US1995151A - Attachment plug cap - Google Patents

Description

March 19, 1935. 'G.-W. LIEBERUM- ATTACHMENT PLUG CAP Filed Feb. 24. 1950- Inventor: George W Liebebum.

His AbtOYn- Q Patented Mar. 19, 1935 PATENT OFFICE ATTACHMENT PLUG CAP George W. Lieberum, Stratford, Conn., assignor to General Electric Company, a corporation of New York Application February 24, 1930, Serial No. 430,697

4 Claims.

The present invention relates to detachable caps for attachment plugs, and has for its object the provision of an improved form of cap. My invention is specifically directed to an improved means for securing the contact elements to the cap without the use of screws or equivalent devices.

For a consideration of what I believe to be novel and my invention, attention is directed to the accompanying description and the claims appended thereto.

In the drawing which is illustrative of my invention, Fig. 1 is a perspective view of a cap; Fig. 2 is an exploded bottom plan view of the cap and contact elements; Fig. 3 is a view of the cap partly in section; and Fig. 4 is a perspective view of one of the contact elements.

The cap or body 5 may be of any suitable contour. As shown it is cup-shaped having a well rounded upper part 6 and a cylindrical lower part '7. In the center is an opening 8 to receive the circuit wires which are attached to the contact elements. The body is cut away on its under side to form a cavity 9, the peripheral wall of which is defined by the part 7. The bottom wall of the cavity is flat or has flat areas perpendicular to the axis of the body to form seats 10 for the contact elements of which there are two arranged in parallel relation.

- In the bottom wall of the cavity are relatively deep and narrow recesses 11 one for each contact element. As these recesses do not extend through the cap the metal parts contained therein are fully insulated. 12 indicates shallow holes 3 to receive the inner ends of the wire binding compression pressure without cracking and capable of withstanding ordinary usage without injury. There are various moldable compositions available for this purpose.

Both contact elements are alike, each being punched from brass or equivalent material. Each contact comprises a base 14 of considerable area which rests on a seat 10 and is provided-with an extension 15 to receive a circuit ire and a binding screw, 13. Extending at right angles to the base is a contact blade 16. Formed integral with the base and extending in the opposite direction from the blade are two prongs 1'7, said prongs being arranged to enter a recess 11 in the body of the cap. These prongs are of such dimensions that when inserted in place they will make a snug fit with the walls of the recess, particularly those portions of the walls at the ends of the recesses. The edges of the prongs may be roughened or serrated to improve the anchoring means. In order to secure the prongs of each element in a recess a wedge 18 is driven in between the prongs after the contact element has been assembled in place.

This wedge spreads the prongs by a slight amount and forces the outer edges into firm contact with the walls of the recess. It is advantageous to have the space between the ends of the prongs a little ,greater than the space between them at' the point-of connection to the base 14, so that when the wedge 18 is forced into place it will be retained by the prongs themselves. .*In other words, the space between the prongs forms a dovetail which is slightly greater in width at the inner ends of the prongs than at the outer ends. The wedge 18 may be made of any suitable material which can readily be expanded or calked into place. For example, I may use lead in the form of an ordinary round shot. When suitable pressure is applied to the lead it will be deformed and press or wedge the inner ends of the prongs apart and largely or wholly fill the space in the recess which is not occupied by the prongs. As will be observed, the recesses 11 are substantially rectangular in shape and each has an enlarged central portion, the purpose of which is to permit of the use of a wedge of substantial proportions and one which is considerably thicker than the prongs. Such an arrangement also provides a relatively'large surface contact area between the metal of the wedge and the surrounding surface of the cap. In assembling, the prongs of the contact elements are forced into the recess by one operation and subsequently the wedges are inserted and expanded.

My improved construction has the advantage that it obviates the use of small parts such as metal inserts molded into the body of the cap and also of screws, which parts are liable to work loose during ordinary use of the cap. Owing to the absence of molded'inserts and screws there results a saving in the cost of masufacture, especially of the body and the cap, and also a saving in the cost of assembly.

What I claim as new and desire to secure by Letters Patent of the United States, is:-

1. In an attachment plug cap, the combination of a cup-shaped body of insulation which has a central opening for circuit wires, flat surfaced seats on opposite sides of the opening and recesses formed adjacent the seats, and a pair of parallel contact elements mounted on the seats, each of said elements having a pair of spaced prongs both of which enter a single recess and a metal wedge located between the prongs which forces their outer edges into firm engagement with opposed walls of said recess.

2. An attachment plugcap comprising a body of molded insulation having preformed recesses, a flat seat, and a wire receiving opening, contact elements mounted on the seat, each of said contacts having a divided prong extending into a recess, the distance between the inner ends of the parts of the prong being greater than at their outer ends, and a wedge that fills the space between the parts of the prong and also forces the outer edges of the prongs into engagement with the end walls of the recess.

3. An attachment plug cap comprising a body of molded insulation having substantially oblong recesses with straight side walls, each or said recesses having an enlargement in the center, a flat seat and a wire receiving opening, contact elements mounted on the seat, each of said elements having a base supported by the seat, a divided prong that extends into a recess, and a soft metal wedge that spreads the parts of the prong and also fills said enlargement.

4. In an attachment plug cap, the combination of a body of molded insulation having a preformed recess and a transverse flat seat, a contact element supported on said seat, said element having a pair of narrow prongs extending perpendicularly to the base, both of which enter the recess and are located side by side therein, and a wedge also located in the recess between the prongs which forces the prongs away from each other into firm contact with the walls of 20 the recess.

GEORGE .W. LIEBERUM.

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