US 3431538 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
March 4, 1969 D. C. HUBBARD ETAL TAP CLAMP Filed Feb. 16. 1967 Fig 4.
INVENTORS. David C. Hubbard David 8. Zumsfeg United States Patent 8 Claims ABSTRACT OF THE DISCLOSURE A tap clamp comprises a pair of opposed clamping ele ments which present two pairs of opposed jaws adapted to receive a line conductor and a tap wire respectively. The contact face of each jaw is elongated and longitudinally serrated, and all of the jaw faces extend in parallelism to thereby grip and hold the conductor and the wire in parallel relationship. The elements are made of a resilient material such as aluminum to compens te for temperature variations and creepage, and to cause the serrations to scrub away nonconductive surface coatings on the conductor and the wire as the elements are drawn together.
The tap wire is initially seated and positively held on the face of one of the wire-receiving jaws during installation of the clamp by a stirrup which partially embraces the jaw, the stirrup having apertured legs through which the tap wire is inserted. When the clamp is later removed from the conductor, the stirrup serves to hold the tap wire securely to the clamp to maintain the wire under control at all times.
The primary object of this invention is to provide a tap clamp that can be remotely installed with a line tool with assurance that the tap wire will remain under control at all times, including the installation and removal operations.
As a corollary to the foregoing object, it is an important aim of the instant invention to provide a tap clamp in which current transfer between the line conduc tor and the tap wire is accomplished with maximum efficiency, yet complete control over the tap wire is maintained when the jaws of the clamp are open as well as closed.
Another important object is to provide a clamp as aforesaid in which the connection effected thereby can move under the influence of creepage or with dimensional changes in the clamp resulting from temperature variations, so that neither will cause loosening of the grip of the clamp.
Still another important object is to provide a tap clamp which may be readily installed on a hot line using a clamp stick, regardless of the attitude of the clamp and without the danger that the clamp will be misinstalled because of the inability of the lineman to closely observe the installation.
In the drawing:
FIGURE 1 is a side elevational view of the clamp showing the tap wire in place with the jaws open;
FIG. 2 is a rear elevational view of the structure shown in FIG. 1;
FIG. 3 is a plan view of the structure shown in FIG. 1;
FIG. 4 is a side view, partially in section and partially in elevation, showing the clamp with the lower jaws in 3,431,538 Patented Mar. 4, 1969 ice contact with the tap wire and the line conductor prior to being advanced into tight engagement therewith; and
FIG. 5 is a view similar to FIG. 4, showing the jaws clamped tightly against the conductor and the wire.
The tap clamp includes a pair of resilient, upper and lower clamping elements 10 and 12 of extruded and tempered aluminum. Element 10 is provided with a pair of spaced jaws 14 and 16 having elongated, transversely concave jaw faces 18 and 20, respectively, extending in parallelism. Each of the faces 18 and 20 has a series of longitudinally extending serrations that present a plurality of teeth. Similarly, element 12 is provided with a pair of spaced jaws 22 and 24 in opposing relationship to upper jaws 14 and 16, and having elongated, longitudinally serrated, transversely concave jaw faces 26 and 28 respectively.
Each of the elements 10 and 12 is centrally apertured to loosely receive a bolt 30 upon which an eye nut 32 is threaded, the latter being adapted to receive a hot line clamp stick. A tab 31 extending from the top of upper element 10 overlies the head of bolt 30 to prevent longitudinal movement thereof relative to element 10. The threaded shank of bolt 30 may be provided with a nylon lock pellet (not shown) to prevent nut 32 from loosening by line vibration. Note that a chamber 33 (FIG. 4) is provided in nut 32 to enclose the bolt threads, and may contain a corrosion inhibiting compound to adapt the clamp to years of use in installations exposed to the elements.
A pair of guards 34 are rigid with the sides of lower element 12 and extend upwardly adjacent the ends of jaw face 20, each guard 34 having a forward edge 34a (FIG. 1) which serves to guide a line conductor C (FIGS. 4 and 5) into face 20 when the clamp is placed on conductor C. Upper jaw 16 is flanged at 36 to further assist in initial placement.
A stirrup 38 has a horizontal bight 40 above upper jaw 14 and a pair of integral, depending legs 42 having aligned openings 44 therein through which a tap wire W is inserted. A bolt 46 is threaded through bight 40 and bears against the upper surface of element 10. Each leg 44 is provided with a guide slot 48 receiving a laterally extending pin or lug 50 projecting from the proximal side of lower jaw 22. Thus, stirrup 38 is retained by pins 50 and the latter cooperate with slots 48 to guide the lower jaw 22 into engagement with wire W during tightening of nut 32.
The lower element 12 follows the movement of nut 32 during loosening of the latter by virtue of a pair of inturned flanges 52 integral with the lower extremities of respective guards 34. Flanges 52 extend beneath an integral ring 54 at the upper end of eye nut 32, interengagement of flanges 52 and ring 54 being effective to hold jaws 16 and 24 open regardless of the attitude of the clamp. Although illustrated herein with bolt 30 extending vertically, installation in other orientations is permitted as desired by the lineman 0r dictated by installation conditions, since jaws 16, 24 will not close by gravity.
To install the clamp, tap wire W is inserted through openings 44 and bolt 46 is tightened to draw wire W into engagement with jaw face 18, the latter presenting a seat for Wire W as is clear in FIG. 1. In hot line work, the linemans clamp stick is then inserted into eye nut 32 and the clamp is installed on line conductor C by hooking flange 36 over conductor C, whereupon the clamp is guided into position with conductor C in engagement with jaw face 20. Edges 34a of guards 34 prevent conductor C from being trapped between elements 10 and 12 interiorly of jaws 16, 24 to thereby preclude connection burn-down due to misinstallation.
As eye nut 32 is tightened to close the lower jaws 22 and 24 against wire W and conductor C, these jaws initially assume an eccentric position with respect to wire W and conductor C as illustrated in FIG. 4. Note that only the outermost teeth of jaws 22 and 241 are in engagement with wire W and conductor C until, as shown in FIG. 5, additional closing pressure is applied by nut 32 to bring the jaws into tight clamping engagement with the conductors. This change from an eccentric to a concentric relationship illustrated by a comparison of FIGS. 4 and is achieved by flexure of element 12, and produces a scrubbing action of the teeth aaginst wire W and conductor C. This is important to the establishment of a low resistance electrical connection since nonconductive surface coatings, including oxides, are oftentimes present on conductors. The scrubbing action, therefore, scrapes away any such coatings and ultimately, as the jaws are fully closed, the teeth bite into the conductors to further assure that a low resistance electrical connection will be established.
By virtue of the resilient character of elements and 12, the clamped connection can move with dimensional changes resulting from temperature variations. Furthermore, the influence of creepage either in the conductors or some component of the clamp will be compensated by flexing of members 10 and 12. Thus, it is assured that the conductors will remain tightly held once th clamp is installed.
An additional feature of the clamp is the electrical efficiency realized by the absence of joints in the clamp structure in the current paths between conductor C and wire W. The two conductors are disposed in parallelism and bridged by the solid, continuous body of each of the elements 10 and 12 (except for the central apertures which receive bolt 30) to maximize the efiiciency of current transfer.
When it is desired to remove the clamp from conductor C, stirrup 38 again securely holds tap wire W in the seat formed by jaw face 18 to provide absolute control of the tap wire even after jaw pressure is removed. The elongated, parallel jaw configuration minimizes conductor deformation and, in conjunction with the action of the stirrup in holding the tap wire W in engagement with jaw face 18 along its entire length, prevents wire W from becoming loose when the jaws'are opened to remove the clamp from conductor C.
Having thus described the invention, what is claimed as new and desired to be secured by Latters Patent is:
1. A tap clamp comprising:
first and second opposed elements each provided with a pair of spaced jaws having elongated, substantially parallel inner faces for receiving a line conductor and a tap wire respectively; a fastener interconnecting the elements for clamping the jaws tightly against the conductor and the wire,
at least one of said elements being of resilient material, whereby the connection effected when the jaws are clamped against the conductor and the wire can move under the influence of creepage or with dimentional changes in the elements resulting from temperature variation; and
structure on said first element engageable with said wire for holding the latter against the wire-receiving face of the first element before the jaws are clamped against the conductor and the wire,
said structure including a stirrup provided with a pair of legs having aligned, wire-receiving openings therein, and means engaging the stirrup for shifting the latter in a direction to draw the wire into the wirereceiving face of the first element when the wire is inserted through said openings.
2. The invention of claim 1,
said fastener interconnecting the elements between the spaced jaws of each element,
each of said faces being transversely concave and having longitudinally extending serrations therein pre senting a plurality of sharp teeth,
the jaw faces of said one element being disposed with only the outermost of said teeth thereof in contact with the conductor and the wire prior to operation of said fasener to clamp the jaws thereagainst whereby, upon tightening of the fastener, said one element flexes to progressively shift the jaw faces thereof into concentric relationship to the conductor and the wire respectively to thereby bite through nonconductive surface coatings on the conductor and the wire by a scrubbing action of the teeth.
3. A tap clamp comprising:
two opposed elements each provided with a pair of spaced jaws having inner faces for receiving a line conductor and a tap wire respectively;
a fastener interconnecting the elements for clamping the jaws tightly against the conductor and the wire; and
structure on one of said elements engageable with said wire for drawing the latter into the wire-receiving face of said one element to hold the wire thereagainst before the jaws are clamped against the conductor and the wire,
said structure including a stirrup provided with a pair of legs having aligned, wire-receiving openings therein, and means engaging the stirrup for shifting the latter in a direction to tighten said wire against said wire-receiving face of the one element when the wire is inserted through said openings.
4. The invention of claim 3,
said elements being normally vertically spaced with the other of said elements disposed beneath said one element,
said fastener extending downwardly from said other element and having means beneath the latter for re ceiving a linemans stick,
there being a guard adjacent the conductor-receiving face of said one element engageable with the conductor for preventing the latter from becoming trapped between the elements other than between the conductor-engaging jaws.
5. The invention of claim 3:
said elements being normally vertically spaced with the other of said elements disposed beneath said one element,
said fastener extending downwardly from said other element and having means beneath the latter for receiving a linemans stick,
said other element being provided with means engaging said fastener and holding the other element with the conductor-receiving face thereof in an open position with respect to the corresponding face of the one element to prevent closure of the conductor-engaging jaws prior to tightening of said fastener, whereby to enable installation of the clamp on the conductor regardless of the attitude of the clamp.
'6. The invention of claim 3,
the jaw faces of each of said elements being elongated in configuration and extending in substantial parallelism to each other.
7. The invention of claim 3,
said legs being spaced apart with the wire-engaging jaw of said one element disposed therebetween,
the face of the last-mentioned jaw being elongated in configuration and defining a seat for said wire,
said stirrup being shiftable to a position where said openings are in longitudinal alignment with said seat.
8. The invention of claim 3,
said elements being normally vertically spaced with the other of the elements disposed beneath said one element,
said fastener being operable to shift said other element upwardly toward said one element,
said stirrup having a bight above said one element, said legs depending from said bight with at least one of the legs having means presenting a guide for said other element during shifting of the latter by said fastener.
References Cited UNITED STATES PATENTS 2,234,022 3/1941 Churchill.
6 2,986,053 5/1961 Atrnan et a1. 81-53 3,248,684 4/1966 Hubbard et a1. 339-95 FOREIGN PATENTS 1,002,302 3/ 1952 France.
MARVIN A. CHAMPION, Primary Examiner.
JOSEPH H. MCGLYNN, Assistant Examiner.
U.S. Cl. X.R.