US2556491A - Clamping cam lug for electrical connections - Google Patents

Description

June 12, 1951 )5 o o 2,556,491

CLAMPING CAM LUG FOR ELECTRICAL CONNECTIONS Filed May 5, 1950 ///////V//I/ //////A IN V EN TOR. MAR/0 MAR/N0 DE LORENZO ATTORNEY Patented June 12, 1951 UNITED STATES PATENT OFFICE CIIAMPING' CAM LUG FORCELECTRICAL CONNECTIONS vMarioMarino .De Lorenzo, 'San Francisco, .Calif.

Application May 1950, Serial No. 160,329

) 2 Claims.

This invention relates to improvement in electrical connection pressure lugs, and relates more particularly to such devices by which a wire conduit may be connected and disconnected at its terminal end without use of tools.

The lug device of the present invention is-a cam clamp into which the terminal ends of a wire conduit may be inserted and securely held, orfrom which the wire may be released without the use of .tools. Inthe. electrical fittings trade such devices .aregenerallyreferred to as lugs.

Thereare manyinstances in electrical installations where it is desired to make a quick and effective releasably tight connection of a terminal end of an electrical circuit wire, without use of tools, such as in various types of telephone panel boards, on board ship where an emergency circuit supplements the regular service circuit, in any installation where it is desired to bring in a main line cireuiton a buss bar and distribute the current to various facilities, quick repair of a broken current-carrying conduit by clamping both ends of the live wire in the lug, etc.

Known lugs present difficulties of operation, in that they require the use of tools to secure or release the circuit wire, and this operation is frequently difficult due to restrictedspace for operation of the tools, and also because screws,'or nuts on binding posts become loose in environments where vibration is inherent, particularly in airplanes, aboard ships; or where "heavy machinery is operated.

The present invention comprises in general a cam pressure clamping lug having a channeled frame'for receiving a conduit terminal in the channel and providing side walls which pivotally mount a cam lever, the cam having a recessed cam face to provide space for reeciving wires of varying sizes, and centering the wire-in the clamp. A'resilient means is interposed between the cam face ofthe lever and floor of the channel to provide 'a resilient relationship between the workingface ofthe cam and'the base, or resiliency may 'be'inherent in the cam. Locking means are provided 'on'the frame for securing the cam in clamping relation'to aninserted wire.

An object of :the invention is to provide a camoperated clamping lug of simple and rugged construction, efficient in operation and economical in manufacture, which is operable without use of toolsfor selectively securing or releasing the terminal ends of'an electric conduit, and maintaining a resilient grip by the cam upon a conduit in the lug.

One form in which the invention may be'ex 2 emplifiedis described herein and illustratedin the accompanying drawing, it being understood that variations of detail may be resorted to without departing'from the invention-which is defined-in the appended claims.

In the drawing:

Fig. 1 is-a longitudinal vertical section of the lug of the invention with alever member at locked position.

Fig. 2 is a front elevation-of the device of Fig. 1.

Fig. 3 is a view similar to Fig. l, withlever at unlocked position.

Fig. 4 is a front end elevation of Fig. 3.

Fig. 5 is a perspective, partly broken away, of a modified form of the invention.

Fig. :6 is a longitudinalvertical-section of device ofFig. 5.

Fig. 7 is a front elevation of device of Fig. 5,- with lever member atraised position.

Referring to the drawing in which like reference characters indicate similar parts in the'several views of corresponding forms of the invention, and referring firstly to the form of invention illustrated in "Figs. 1 to 4, lfl'indicates-generally a supporting frame providing an elongated planar base plate l l, having at one end relatively spaced opposed upstanding side walls I2, one at each longitudinal side of the base, providing therebetween a channel l3, the side walls preferably terminating centrally of the'length of the base member H, and'the latter having an extension Ha rearwardly thereof. Adjacent the forward end and the upper edge of the side walls there is 'an opening [-4 for a pivot pin l5.

A cam It having an-elong-ated rearwardly extending lever handle portion H is pivotally mounted between the sidewalls l2 upon the pivot pin it, the working face'of the cam being ellipsoidally eccentric to pin 5 with a slightly greater radius atthecamhead -l 8 than at the nose I9.

The central portion of the head portion [8 of the cam has an arcuate recess or groove 20 substantiallyperpendicular to the length of the lever handle, providing on each side of the opposite sides of the recess'elongated relatively narrow arcuate strips lila which are a part of the cam working face.

Overlying the base plate H is a leaf spring member 2! mounted in the channel l3, the forward planar end portion underlying the cam, and the opposite end portion extending rearwardly to overlie the rear portion Hat of the base plate, to which'it may be tightly "securedby any suitable means such as a peened'eyelet or'grommet'23 mounted through a hole in the rear portion IIa of the base plate.

The forward end portion of the leaf spring 2I which underlies the cam is provided with an integral vertically offset planar portion 24 transversely of the channel, the offset planar portion being spaced from the opposing face of the base member by inclined walls 25, the foot of the walls being in contact with the base member within the channel and furnishing a resilience to the offset planar portion. Centrally of the planar portion 24 of the spring strip is an integral upset transverse tooth 2'6. The arcuate strips IBa of the cam face each has a groove or notch 21 therein, and the radius of the cam at the grooves 2'! is sufficient for the tooth to engage in the groove when the cam lever is appropriately moved perpendicular to the base, as will be described. If desired, there may be a plurality of such teeth 26 or grooves 21. The lesser radius of the cam nose I9 is sufiicient for the cam nose to superficially contact the tooth 26.

Means are provided at the rear end Ila of the base for releasably holding the lever I! at a position whereby the cam nose I9 is in locked relation to the tooth of the spring member. Such means may comprise a spring finger 28 which is a vertically turned extension of the rear end portion leaf spring 2I, the spring finger having a snap-lock 29 to engage and releasably hold the end of the cam lever If at its free end, and hav ing a stop member to limit the downward movement of the lever at the locking position of the cam nose.

In operation of the device illustrated in Figs. 1 to 4, the channeled frame IIl may be secured to an appropriate terminal base by screw 3I passing through eyelet 23, by first releasing the snap catch 29 and lifting the lever Ii perpendicular to the base plate, at which position the lever may be releasably held by engagement of the tooth 26 in the notch 21, since at such position of the lever it is desirable to maintain the lever and the cam against falling either forwardly or rearwardly when inserting a wire A or when inserting and cinching screw 3 I. This, likewise, is the position of the lever at the time of inserting the terminal end of a wire as shown in Fig. 3. At the perpendicular position of the lever, the bottom wall recess 20 is parallel to the planar portion 24 and the cam faces of the side strips I8a at the head of the cam are closely adjacent the face of said planar portion, thus providing at the forward end of the lug an arcuate passageway 29a of large cross sectional area for insertion of wires of varying gauges, and thus centering the wire in the channel. After the Wire is inserted the lever is pressed rearward and downward to the position shown in Fig. l, whereupon the nose IQ of the working face of the cam engages the wire and firmly presses it into holding engagement with the tooth 28. The working face of the cam at the nose i9 is of sufficiently lesser diameter than the radius at the cam head I8 so that the nose of the cam, when in locked position, is in substantial superficial contact with the tooth whereby even a small gauge wire may be held therebetween, yet due to the resilience of the offset planar portion 24 0f the spring leaf member, upon which the tooth 26 is mounted, a substantial range of gauges of Wire may be secured within a single clamping lug.

When the wire is properly locked by the nose of the cam the free end of the handle lever I1 is pressed under the spring snap-lock 29 and since its further downward movement might have a tendency to push the engaged wire forward, or to release the wire-engaging of the cam, the stop member 30 will limit the further downward movement of the lever.

The invention is not limited, however, to a cam having a solid rigid body nor the specific type of vertically offset resilient planar spring portion, as shown at 24 in Figs. 1 to 4. As a modified form of the invention there is shown in Figs. 5 to 7, a cam device of arcuately bent spring strip metal in which the frame Ii], sidewalls I2, base member I I, Ila and snap- lock 28a, 29a, 3011 may be substantially similar as previously described. The cam member IGa is a loop of spring steel strip having one end welded or soldered as at IE?) to a handle lever I'Ia which has an opening therethrough to receive the pivot pin I5a. The Working face of the cam IBa may be eccentric as previously described, the radius at the head 3| of the cam being greater than at the cam nose 32.

The free terminal end of the spring strip cam 602 of this modification is preferably provided with a lip 33 which has sliding contact with the underface of the cam lever Ila, and a slot 201) in the arc of the cam head may provide the equivalent of a recess. An indent 21a may be provided in the arcuate side strips I8b of the working face of the head portion of the cam. The slot 2% and indents 21a in this modification are for purposes and functions similar to indent 2i and recess 29 in the device of Figs. 1 to 4. In this modification since the cam member Ifia is of spring strip metal, it is not essential that a spring strip be employed within the channel overlying the base El, and the tooth 28a may be integral with the base wall H. The spring snap-lock 29a and stop member 36a may be retroverted upon an upstanding spring finger 28a the base of which is secured to the rearward portion Iia of the base member by the open eyelet 23a, which also provides an opening for a screw by which the device may be suitably affixed to a terminal.

The manipulation and operation of the modification to engage and release a wire in the clamp lug is similar to that previously described except that the resilient relationship between the cam face and the tooth is inherent in the cam face rather than in the tooth.

Having described the invention, what is claimed as new and patentable is:

l. A pressure clamping lug including an elongated channeled frame having relatively spaced opposed side walls and a base, an integral cam and lever pivotally mounted between the side walls for pivotal movement in the channel for locking a wire therein, the cam being provided with a working face having a head portion recess-ed centrally substantially perpendicular to the lever and providing a side strip on each side of the recess, and said cam having a nose portion operable for engaging a wire between the cam and base plate, the side strips of the head portion having a greater pivotal radius than the nose portion of the cam, said base member having an upstanding tooth underlying the cam transversely of the channel, and said head portion of the cam having a transverse indented groove for engagement of said tooth when the cam lever is at a position substantially perpendicular to the base.

2. A clamping lug having the elements of claim 1, and in which the nose of the cam and the base member have a resilient pressure relationship when a wire member is engaged therebetween.

MARIO MARINO DE LORENZO.

REFERENCES CITED The following references are of record in the file of this patent: m

Number 6 UNITED STATES PATENT Name Date Kolb "111 June 26, 1877 Jones ..May 17, 1887 Rankin Aug. 22, 1899 Jeralds ;Apr. 16, 1907 Ofstedahl "July 14, 1925 Gronquist Oct. 28, 1930 Frank 'A 1-. 15, 1941

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