HOT LINE CLAMP
United States Patent 3629805
A hot line clamp having a clamp body and a keeper for clamping a main conductor and a tap conductor against the body, with a clamp bolt for drawing the keeper and body together. An auxiliary clamp jaw is interposed between the keeper and the body and has means associated therewith for drawing it toward the body initially to clamp the tap conductor against the body independently of the clamp bolt. The keeper, when drawn toward the body, engages the auxiliary jaw and acts via the latter to apply additional clamping pressure to the tap conductor for high-pressure electrical contact purposes.
US Patent References:
Battery terminal connecter
Eberling - June 1925 - 1542680
Cable tapping device
Hixon - May 1939 - 2159154
Line clamp
Becker - October 1957 - 2811703
Hot line clamp
Roosman - July 1964 - 3142525
TAP CLAMP
Hubbard et al. - March 1969 - 3431538
Battery terminal connecter
Eberling - June 1925 - 1542680
Cable tapping device
Hixon - May 1939 - 2159154
Line clamp
Becker - October 1957 - 2811703
Hot line clamp
Roosman - July 1964 - 3142525
TAP CLAMP
Hubbard et al. - March 1969 - 3431538
Application Number:
04/797009
Publication Date:
12/21/1971
Filing Date:
02/06/1969
View Patent Images:
Export Citation:
Assignee:
Anderson Electric Corporation (Leeds, AL)
Primary Class:
Other Classes:
23/294R, 439/864, 439/477
International Classes:
H01R11/15; H01R11/11; H01R7/22
Field of Search:
339/109,264L,266L,263L,265F,274 85/61
Primary Examiner:
Moore, Richard E.
Claims:
I claim
1. A hot line clamp comprising a clamp body, a keeper selectively movable toward and away from the body respectively to effect clamping and unclamping of a main conductor between the keeper and the body, means for selectively effecting clamping and unclamping movement of the keeper relative to the body, an auxiliary clamp element interposed between the keeper and the body for initially clamping a tap conductor between the auxiliary clamp element and the body, the auxiliary clamp element being integral with and disposed eccentrically of an unthreaded first end portion of a bolt having a threaded second end portion extending through a hole in the body, the bolt being disposed completely on one side of each of a pair of perpendicularly disposed reference planes intersecting at an axis of the means for effecting clamping and unclamping movement and the auxiliary clamp element being substantially bisected by one of the reference planes, and a nut threaded on the second end portion of the bolt and turnable in a clamping direction to effect initial clamping of the tap conductor between the auxiliary clamp element and the body eccentrically of the bolt, the keeper engaging the auxiliary clamp element when the keeper is moved in the clamping direction and acting via the auxiliary clamp element to apply clamping pressure to the tap conductor augmenting the initial clamping of the tap conductor by the auxiliary clamp element.
2. A hot line clamp as set forth in claim 1 wherein the clamp body is formed for receiving the tap conductor laterally with respect to the main conductor and the auxiliary clamp element is adapted for clamping the tap conductor to the clamp body in position extending laterally with respect to the main conductor.
3. A hot line clamp as set forth in claim 2 wherein the clamp body and auxiliary clamp element are formed for clamping the tap conductor to the clamp body with the tap conductor angled laterally outward and downward with respect to the clamp body.
4. A hot line clamp as set forth in claim 1 wherein the clamp body has a downwardly opening groove for receiving the main conductor and a downwardly opening groove for receiving the tap conductor, the keeper being movable upward relative to the clamp body by said means for effecting clamping movement of the keeper for clamping the conductors in their respective grooves, the auxiliary clamp element being interposed between the keeper and the tap conductor groove.
5. A hot line clamp set forth in claim 4 wherein the means for effecting clamping movement of the keeper comprises a clamp bolt extending upward through an opening in the keeper and threaded in a tapped hole in the clamp body.
6. A hot line clamp as set forth in claim 5 wherein the clamp bolt has an eye at its lower end for reception of a hook on a hot stick and a head above the eye with a shear section between the eye and the head adapted for shearing off of the eye on application thereto of torque exceeding a predetermined value, leaving the head intact for application thereto of a tool for turning the bolt to remove the clamp.
7. A hot line clamp as set forth in claim 5 wherein the opening in the keeper is formed to allow rocking movement of the keeper relative to the bolt.
8. A hot line clamp as set forth in claim 7 wherein the bolt has an upper collar above the keeper and a lower collar below the keeper, the opening in the keeper being a keyhole slot having an enlarged portion for passage of the upper collar and a smaller portion having a width less than the diameter of the upper collar.
9. A hot line clamp as set forth in claim 8 wherein the keeper has a pair of downwardly extending stabilizing lugs on opposite sides of the bolt for cooperation with a hot stick.
10. A hot line clamp as set forth in claim 4 wherein the tap conductor groove extends laterally with respect to the main conductor groove.
11. A hot line clamp as set forth in claim 10 wherein the tap conductor groove is angled laterally outward and downward with respect to the clamp body.
12. A hot line clamp as set forth in claim 5 wherein the clamp bolt has at least one interruption in its screw thread for removal of foreign matter on turning of the clamp bolt to open the clamp to prevent galling or jamming of the screw threads on the clamp bolt and in said tapped hole.
13. A hot line clamp as set forth in claim 12 wherein the clamp bolt has a screw-threaded upper end portion and a plurality of longitudinal grooves in its periphery constituting interruptions, said grooves extending upward from the lower end of said upper end portion and terminating short of the upper end of said upper end portion.
14. A hot line clamp comprising a clamp body having a first groove for receiving a main conductor and a second groove for receiving a tap conductor, a keeper movable toward and away from the body respectively to effect clamping and unclamping of the main conductor in the first groove, a clamp bolt extending through an opening in the keeper, threaded in a tapped hole in the body, and rotatable in opposite directions selectively to effect clamping and unclamping movement of the keeper relative to the body, an auxiliary clamp element interposed between the keeper and the second groove for initially clamping the tap conductor in the second groove, and means independent of the clamp bolt for effecting clamping movement of the auxiliary clamp element relative to the body to clamp the tap conductor in the second groove initially, the keeper engaging the auxiliary clamp element when the keeper is moved in the clamping direction and acting via the auxiliary clamp element to apply clamping pressure to the tap conductor augmenting the initial clamping of the tap conductor by the auxiliary clamp element, the clamp bolt having an eye at an outer end for reception of a hook on a hot stick, a head between the eye and the end threaded in the body, and a shear section between the eye and the head, and the eye shearing off upon application of torque thereto above a predetermined value, leaving the head intact for application of a tool thereto for turning the remainder of the clamp bolt to remove the clamp from the main conductor.
15. A hot line clamp as claimed in claim 14 wherein the clamp bolt has an inner collar on the side of the keeper adjacent the body and an outer collar on the remote side of the keeper from the body and the opening in the keeper is formed to allow rocking movement of the keeper relative to the clamp bolt, being a keyhole slot having an enlarged portion for passage of the inner collar and a smaller portion having a width less than the diameter of the inner collar.
16. A hot line clamp as claimed in claim 15 wherein the keeper has a pair of stabilizing lugs on opposite sides of the clamp bolt for cooperation with a hot stick.
17. A hot line clamp as claimed in claim 14 wherein the auxiliary clamp element is integral with and disposed eccentrically of an unthreaded first end portion of a bolt having a threaded second end portion extending through a hole in the body, and the means for effecting clamping movement of the auxiliary clamp element includes a nut threaded on the second end portion of the bolt on the opposite side of the body from the auxiliary clamp element.
1. A hot line clamp comprising a clamp body, a keeper selectively movable toward and away from the body respectively to effect clamping and unclamping of a main conductor between the keeper and the body, means for selectively effecting clamping and unclamping movement of the keeper relative to the body, an auxiliary clamp element interposed between the keeper and the body for initially clamping a tap conductor between the auxiliary clamp element and the body, the auxiliary clamp element being integral with and disposed eccentrically of an unthreaded first end portion of a bolt having a threaded second end portion extending through a hole in the body, the bolt being disposed completely on one side of each of a pair of perpendicularly disposed reference planes intersecting at an axis of the means for effecting clamping and unclamping movement and the auxiliary clamp element being substantially bisected by one of the reference planes, and a nut threaded on the second end portion of the bolt and turnable in a clamping direction to effect initial clamping of the tap conductor between the auxiliary clamp element and the body eccentrically of the bolt, the keeper engaging the auxiliary clamp element when the keeper is moved in the clamping direction and acting via the auxiliary clamp element to apply clamping pressure to the tap conductor augmenting the initial clamping of the tap conductor by the auxiliary clamp element.
2. A hot line clamp as set forth in claim 1 wherein the clamp body is formed for receiving the tap conductor laterally with respect to the main conductor and the auxiliary clamp element is adapted for clamping the tap conductor to the clamp body in position extending laterally with respect to the main conductor.
3. A hot line clamp as set forth in claim 2 wherein the clamp body and auxiliary clamp element are formed for clamping the tap conductor to the clamp body with the tap conductor angled laterally outward and downward with respect to the clamp body.
4. A hot line clamp as set forth in claim 1 wherein the clamp body has a downwardly opening groove for receiving the main conductor and a downwardly opening groove for receiving the tap conductor, the keeper being movable upward relative to the clamp body by said means for effecting clamping movement of the keeper for clamping the conductors in their respective grooves, the auxiliary clamp element being interposed between the keeper and the tap conductor groove.
5. A hot line clamp set forth in claim 4 wherein the means for effecting clamping movement of the keeper comprises a clamp bolt extending upward through an opening in the keeper and threaded in a tapped hole in the clamp body.
6. A hot line clamp as set forth in claim 5 wherein the clamp bolt has an eye at its lower end for reception of a hook on a hot stick and a head above the eye with a shear section between the eye and the head adapted for shearing off of the eye on application thereto of torque exceeding a predetermined value, leaving the head intact for application thereto of a tool for turning the bolt to remove the clamp.
7. A hot line clamp as set forth in claim 5 wherein the opening in the keeper is formed to allow rocking movement of the keeper relative to the bolt.
8. A hot line clamp as set forth in claim 7 wherein the bolt has an upper collar above the keeper and a lower collar below the keeper, the opening in the keeper being a keyhole slot having an enlarged portion for passage of the upper collar and a smaller portion having a width less than the diameter of the upper collar.
9. A hot line clamp as set forth in claim 8 wherein the keeper has a pair of downwardly extending stabilizing lugs on opposite sides of the bolt for cooperation with a hot stick.
10. A hot line clamp as set forth in claim 4 wherein the tap conductor groove extends laterally with respect to the main conductor groove.
11. A hot line clamp as set forth in claim 10 wherein the tap conductor groove is angled laterally outward and downward with respect to the clamp body.
12. A hot line clamp as set forth in claim 5 wherein the clamp bolt has at least one interruption in its screw thread for removal of foreign matter on turning of the clamp bolt to open the clamp to prevent galling or jamming of the screw threads on the clamp bolt and in said tapped hole.
13. A hot line clamp as set forth in claim 12 wherein the clamp bolt has a screw-threaded upper end portion and a plurality of longitudinal grooves in its periphery constituting interruptions, said grooves extending upward from the lower end of said upper end portion and terminating short of the upper end of said upper end portion.
14. A hot line clamp comprising a clamp body having a first groove for receiving a main conductor and a second groove for receiving a tap conductor, a keeper movable toward and away from the body respectively to effect clamping and unclamping of the main conductor in the first groove, a clamp bolt extending through an opening in the keeper, threaded in a tapped hole in the body, and rotatable in opposite directions selectively to effect clamping and unclamping movement of the keeper relative to the body, an auxiliary clamp element interposed between the keeper and the second groove for initially clamping the tap conductor in the second groove, and means independent of the clamp bolt for effecting clamping movement of the auxiliary clamp element relative to the body to clamp the tap conductor in the second groove initially, the keeper engaging the auxiliary clamp element when the keeper is moved in the clamping direction and acting via the auxiliary clamp element to apply clamping pressure to the tap conductor augmenting the initial clamping of the tap conductor by the auxiliary clamp element, the clamp bolt having an eye at an outer end for reception of a hook on a hot stick, a head between the eye and the end threaded in the body, and a shear section between the eye and the head, and the eye shearing off upon application of torque thereto above a predetermined value, leaving the head intact for application of a tool thereto for turning the remainder of the clamp bolt to remove the clamp from the main conductor.
15. A hot line clamp as claimed in claim 14 wherein the clamp bolt has an inner collar on the side of the keeper adjacent the body and an outer collar on the remote side of the keeper from the body and the opening in the keeper is formed to allow rocking movement of the keeper relative to the clamp bolt, being a keyhole slot having an enlarged portion for passage of the inner collar and a smaller portion having a width less than the diameter of the inner collar.
16. A hot line clamp as claimed in claim 15 wherein the keeper has a pair of stabilizing lugs on opposite sides of the clamp bolt for cooperation with a hot stick.
17. A hot line clamp as claimed in claim 14 wherein the auxiliary clamp element is integral with and disposed eccentrically of an unthreaded first end portion of a bolt having a threaded second end portion extending through a hole in the body, and the means for effecting clamping movement of the auxiliary clamp element includes a nut threaded on the second end portion of the bolt on the opposite side of the body from the auxiliary clamp element.
Description:
BACKGROUND OF THE INVENTION
This invention relates to hot line clamps, i.e., a clamp for connection of a tap conductor to a main conductor (the "hot line") in an electric power distribution system.
The invention is particularly concerned with improvements on hot line clamps of the general type shown in such U.S. Pat. Nos. as 2,651,766, 2,867,787, 3,075,166, 3,177,459 and 3,142,525, adapted for initial application to the clamp of a tap conductor, and application of the clamp with the tap conductor connected thereto to a hot line by use of a hot stick. One of the problems involved in such clamps is that of attaining high pressure electrical contact between the clamp parts and the conductors, particularly the tap conductor, while permitting easy initial application of the tap conductor to the clamp in such manner as to prevent pullout of the tap conductor while the clamp is being applied to the hot line. In the clamps such as shown in the last four patents mentioned above, the end of the tap conductor is both initially and finally clamped by means of a tap conductor clamping bolt or screws wholly independently of the main clamping bolt of the clamp, and while this may provide for an initial firm grip on the tap conductor, it may not always provide for maintenance of high pressure electrical contact between the clamp parts and the tap conductor, due, for example, to relaxation of the grip of the tap conductor clamping bolt or screws on the tap conductor. As regards the hot line clamp shown in U.S. Pat. No. 2,651,766, for example, while the tap conductor as well as the main conductor are ultimately both pressured by the keeper, the initial grip of the tap conductor is simply by spring action, and this may not be sufficient to prevent the tap conductor from pulling out when the clamp is being applied to the hot line. Another problem involved in clamps such as described arises from the possibility that a lineman may in certain instances apply excessive torque to the bolt while the clamp is being installed on the hot line, causing mechanical failure of the clamp such that it may fall off the hot line. In some instances a clamp which has failed because of overtorquing may remain on the hot line, rather than falling off, and it is then desirable to remove it to avoid a cluttered appearance, but removal of failed prior clamps has heretofore been impossible without cutting them from the hot line.
SUMMARY OF THE INVENTION
Among the several objects of this invention may be noted the provision of an improved hot line clamp which provides for better electrical interconnection of the main and tap conductors via sustained high pressure electrical contact between the clamp parts and the conductors, also providing for a firm grip on the tap conductor initially effectively to prevent it from pulling out of the clamp when the clamp is applied to the hot line; the provision of such a clamp wherein current is conducted from the main conductor to the tap conductor via both the body of the clamp and a keeper of the clamp so that the clamp is of the "double-bridge" type; the provision of such a clamp which is adapted to remain clamped on the main conductor in the event it is subjected to excessive torque when being applied to the main conductor, and which, in the event of such overtorquing, can be readily removed without having to cut it off the main conductor; the provision of such a clamp wherein the direction of takeoff of the tap conductor from the clamp is in a plane perpendicular to the direction of length of the main conductor and angled downward and outward from the clamp, as is preferable to the direction of takeoff of the tap conductor being parallel to the main conductor; the provision of such a clamp in which the thread on the clamp bolt and the thread in the clamp body are protected from both electrical arc and environmental conditions; and the provision of such a clamp adapted for automatic initial gripping of the tap conductor.
In general, a hot line clamp of this invention comprises a clamp body, a keeper for clamping a main conductor and a tap conductor against the body, means for effecting clamping movement of the keeper, an auxiliary clamp element interposed between the keeper and the body for initially clamping the tap conductor against the body, and means for effecting clamping movement of the auxiliary clamp element independently of the means for effecting clamping movement of the keeper initially to grip the conductor. With this arrangement, the keeper, when moved in clamping direction, engages the auxiliary clamping element and acts via the latter to apply clamping pressure to the tap conductor augmenting the initial grip of the auxiliary clamp element on the tap conductor for sustained high pressure electrical contact as between the body, the keeper and the tap conductor as well as between the body, the keeper and the main conductor. Other objects and features will be in part apparent and in part pointed out hereinafter.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a view in elevation of a hot line clamp of this invention, taken in the direction of the length of a main conductor on which the clamp is applied, and showing the clamp in an opened position;
FIG. 2 is a plan of FIG. 1;
FIG. 3 is a right side elevation of FIG. 1;
FIG. 4 is a left side elevation of FIG. 1;
FIG. 5 is a section on line 5--5 of FIG. 1;
FIG. 6 is a section on line 6--6 of FIG. 3;
FIG. 6A is a view showing a modified type of eyebolt for the FIG. 1 clamp;
FIG. 7 is a section on line 7--7 of FIG. 1;
FIG. 8 is a section on line 8--8 of FIG. 1;
FIG. 9 is a section similar to FIG. 6 but showing the clamp closed on a main conductor and a tap conductor;
FIG. 10 is a view in elevation of another embodiment of the hot line clamp of this invention, taken (like FIG. 1) in the direction of the length of a main conductor on which the clamp is applied, and showing the clamp in an opened position;
FIG. 11 is a plan of FIG. 10;
FIG. 12 is a right side elevation of FIG. 10;
FIG. 13 is a section on line 13--13 of FIG. 12;
FIG. 14 is a section on line 14--14 of FIG. 10; and
FIG. 15 is a view similar to FIG. 10 but showing the clamp closed on a main conductor and a tap conductor.
Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIGS. 1-9 of the drawings, a first version of the hot line clamp of this invention is designated in its entirety by the reference numeral 1. As shown therein, the clamp 1 comprises a clamp body 3, which may be cast of a suitable electrically conductive metal such as aluminum or bronze. Associated with the body 3 is a keeper 5 for effecting gripping of the clamp on a main conductor M and gripping to the clamp of a tap conductor T. At 7 is indicated means constituted by an eyebolt for effecting clamping movement of the keeper relative to the body to clamp the main and tap conductors against the body. Also associated with the body is an auxiliary clamp element 9 constituted by a jaw at the lower end of a bolt 11, this element or jaw 9 being interposed between the keeper and the body and being adapted for initially clamping the tap conductor T against the body independently of the keeper. The bolt 11 is disposed completely on one side of each of a pair of perpendicularly disposed reference planes intersecting at an axis of the eyebolt 7 and represented respectively by the lines 5--5 in FIG. 1 and 6--6 in FIG. 3, and the auxiliary clamp element 9 is bisected by the reference plane represented by line 6--6 in FIG. 3. Means for effecting clamping movement of the auxiliary clamp element 9 independently of the eyebolt 7 is shown to constitute a nut 13 threaded on the bolt 11. The keeper 5, when moved in clamping direction by the eyebolt 7 to clamp the main and tap conductors M and T, engages the auxiliary clamp element 9 and acts via the latter to apply clamping pressure to the tap conductor augmenting the initial grip of element 9 on the tap conductor.
More particularly, the body 3 has a central portion 15 having a top wall 17, sidewalls 19 and 21, and end walls 23. The sidewall 19 extends down from the top wall somewhat farther than the sidewall 21. The end walls 23 extend down from the top wall somewhat farther than the sidewall 19. The central portion 15 of the body is formed with a relatively wide internal web 25 extending down from the top wall somewhat farther than the sidewall 19 spanning the sidewalls 19 and 21 and located generally centrally between the end walls 23. This leaves a pair of recesses 27 between the internal web 25 and the end walls, these recesses opening downward. The central portion 15 of the body is also formed with a dome-shaped boss 29 extending upward from the top wall 17 in alignment with the internal web 25. A tapped hole 31 extends upward from the bottom of the internal web 25 into the boss 29, terminating short of the upper end of the boss so that the latter is closed at the top for protection of the thread in the hole. This hole is slightly offset from the center of length of the web 25 toward the sidewall 19.
A jaw 33 extends laterally outward from sidewall 19 of the central portion 15 of body 3, this jaw being angled outward and downward from sidewall 19. It is formed with a downwardly opening groove 35 for receiving the main conductor M. End walls 23 of the central portion 15 of body 3 are notched as indicated at 37 at the ends of groove 35 for receiving the main conductor.
A jaw formation 39 extends laterally outward from the sidewall 21 of the central portion 15 of the body 3. This jaw formation 39 has an upper portion 41 angled downward from the body 3 formed with a downwardly facing groove 43 for receiving the tap conductor T. It also has an outer end portion 45 extending downward from the outer end of upper portion 41 formed with a downwardly opening slot 47. End portion 45 is spaced laterally outward from the sidewall 21 of the central portion 15 of the body 3, forming a downwardly opening channel 49 extending horizontally endwise in respect to the body on the opposite side thereof from the main conductor groove 35 (this channel 49 extending parallel to the main conductor groove 35). The jaw formation 39 has a bolt hole 51 in the top thereof toward one end of the body, this hole being located alongside the tap conductor groove 43. The latter groove extends at right angles to the main conductor groove 35. The body 3 also has a pair of tongues 53 extending downward from the ends of the sidewall 21 of its central portion 15. These tongues are initially formed to extend vertically downward, but are subsequently bent to an angled position as shown in FIG. 1 for a purpose that will appear.
The keeper 5, which like the body 3 is cast of a suitable electrically conductive metal such as aluminum or bronze, has an arcuate bottom wall 55, the width of which is slightly less than the spacing of the tongues 53 and the end walls 23 of central portion 15 of the body so as to have a loose fit therebetween. The keeper 5 has upwardly extending end walls 57 at the ends of its arcuate bottom wall, these end walls having upwardly projecting tongues 59 adapted for reception in the recesses 27 in the central portion 15 of body 3. The keeper is formed at one side thereof with a jaw 61 for clamping the main conductor M in the groove 35 and is adapted for engagement of its other side 63 with the auxiliary clamp element 9, as will appear. Jaw 61 has portions 61a extending beyond the keeper end walls 57, the length of jaw 61 corresponding to the length of the main conductor groove 35. Lugs or pins 65 extend outward from the keeper end walls 57 at its said other side. The arcuate bottom wall 55 of the keeper is formed with a slot 67 for the eyebolt 7, this slot being in the form of a keyhole slot having an enlarged section 67a toward side 63 of the keeper. The keeper also has a pair of lugs 69 extending downward at opposite ends thereof, these lugs being offset outward from the keeper end walls 57.
The eyebolt 7 (which may also be formed of an electrically conductive metal such as bronze) comprises an eye 71 having a stem 73 joined to one end (the lower end) of hexagonal head 75. This head has a circular flange 77 at its other (upper) end. The shank 79 of the eyebolt extends upward from this flange. The shank 79 has a diameter slightly less than the width of the smaller portion of the keyhole slot in the keeper. It is formed with an integral circular collar 81 spaced from flange 77, this collar having a diameter larger than the width of the smaller portion of the keyhole slot 67 but smaller than the width of the enlarged portion 67a of the keyhole slot. The shank is threaded at its upper end as indicated at 83 for being threaded in the tapped hole 31 in the body 3. The stem 73 has an annular groove 84 at its juncture with the head 75, to provide a weakened juncture adapted to fail in shear if the eyebolt is overtorqued.
The bottom portion of the threads on the threaded upper end 83 of shank 79 of the eyebolt are interrupted as indicated at 83a, the interruptions being constituted by grooves extending upward from the lower end of the threaded end portion 83 a distance somewhat less than the length of portion 83. These interruptions or grooves 38a provide for relief in the portion 83 to remove any foreign material such as dust or particles of grit that may accumulate in the threads in hole 31 of the body 3 during service. When the eyebolt 7 is rotated in the direction to open clamp, the body threads are wiped clean to prevent galling or jamming of the threads.
FIG. 6A illustrates a modified type of eyebolt 7a which may be used instead of the eyebolt 7. This differs from the eyebolt 7 essentially only in that it has a head in the form of a second eye 75a above the eye 71 instead of the hexagonal head 75, with the shear failure groove 84 between these eyes. The provision of eye 75a permits a lineman to remove the clamp from the main conductor without the use of a wrench adapter on his hot line stick, if the primary eye 71 should shear off during installation.
As previously mentioned, the auxiliary clamp element 9 is constituted by a jaw at the lower end of a bolt 11. This bolt 11 has a generally cylindric head 85 at one end constituting its lower head. The auxiliary clamping element of jaw 9 is formed integrally with head 85 at one side thereof. As shown best in FIGS. 7 and 9, it is of generally triangular form, having an inclined upper surface 87, a vertical surface 89, and a bottom 91. The upper surface 87 is formed with a groove 93 extending lengthwise thereof, and the bottom is formed with a groove 95 extending transversely thereof (i.e., groove 95 extends transversely with respect to groove 93). The slope of surface 87 (and groove 93) matches the slope of the tap conductor groove 43 in the body 3. The bolt 11 and jaw 9 integral therewith are preferably formed of a suitable electrically conductive metal such as bronze.
As previously noted, the tongues 53 are initially formed to extend vertically downward from the body 3. With the tongues 53 in this initial condition, the parts are assembled as follows:
The bolt 11 is inserted upward through hole 51, with the jaw 9 in position transverse to the clamp body 3 (i.e., in a plane at right angles to the plane of the main conductor groove 35), and with the grooved upper surface 87 of the jaw 9 opposed to the downwardly facing tap conductor groove 43 in the clamp body. The toe of the jaw 9 extends into the slot 47 and is vertically slidable in the slot 47. The grooved bottom 91 of jaw 9 lines up with the channel 49. A spring washer 97 and nut 13 are applied to the upper end of the bolt. A washer 99 having an internal diameter larger than that of collar 81 is applied to the shank 79 of the eyebolt 7, bearing against flange 77 on the hexagonal head 75 of the eyebolt, and the keeper 5 is applied to the shank of the eyebolt by passing collar 81 through the enlarged portion 67aa of the keyhole slot 67 in the arcuate bottom wall 55 of the keeper. The lugs 69 which extend downward from the keeper straddle the washer 99 and flange 77. The threaded upper end 83 of the eyebolt is then threaded in the tapped hole 31 in the clamp body 3, the jaw 61 of the keeper being opposed to the main conductor groove 35 in the body, and the side 63 of the keeper being registered with the channel 49 in the body, the pins 65 of the keeper being slidable on the surfaces of tongues 53 which face outward toward the end portion 45 of jaw formation 39. Then the tongues 53 are bent laterally outward in the direction toward end portion 45 of jaw formation 39 to hold the keeper and eyebolt captive to the body 3 (see FIGS. 1, 6 and 9 showing the tongues so bent).
The clamp 1 is utilized by a lineman in the following manner:
With the eyebolt 7 and nut 13 backed off as shown in FIGS. 1, 6 and 7, so that the keeper 5 is in an open retracted position and so that the jaw 9 is in an open retracted position with respect to the grooved fixed jaw portion 41 of the body 3, the end of the tap conductor T is entered between jaw 9 and fixed jaw portion 41, and nut 13 is turned to draw up the bolt 11 and the jaw 9 so that the end of the tap conductor is clamped in groove 43 of the body 3 by jaw 9. The nut 13 is turned to draw up jaw 9 for initial clamping of the tap conductor with sufficient grip to prevent the tap conductor from pulling out when the clamp 1 is subsequently applied to the main conductor M.
With the tap conductor T so gripped in the clamp 1, the latter is mounted on the end of a lineman's hot stick, the usual hook on the hot stick being entered in the eye 71 of eyebolt 7, the hot stick being activated to draw the lugs 69 of the keeper 5 into the head of the hot stick for stabilizing the clamp on the hot stick. The hot stick is then used to apply the clamp 1 to the main conductor, by hooking jaw 33 over the main conductor, the latter being accommodated in the groove 35. The hot stick is then pulled downward to disengage the lugs 69 from the hot stick head, so that the hot stick may be rotated to turn the eyebolt 7, and the hot stick is then rotated to turn the eyebolt in the direction to cause the eyebolt to be drawn upward relative to the clamp body 3 (by the threading of the threaded upper end 83 of the eyebolt into the threaded bore 31).
The keeper 5 (which bears against washer 99 on flange 77 of the eyebolt) moves upward relative to body 3 along the eyebolt to the point where jaw 61 of the keeper engages the main conductor M or the side 63 of the keeper engages jaw 9. On continued upward movement of the keeper by turning of the eyebolt, the keeper rocks relative to the eyebolt (as permitted by the arcuate form of the bottom wall 55 of the keeper and the play of the keeper with respect to the eyebolt permitted by slot 67) so that contact is established not only between jaw 61 of the keeper and the main conductor M but also between side 63 of the keeper and jaw 9. Turning of the eyebolt is continued after this double contact has been established so that high pressure is applied to the main conductor by jaw 61 of the keeper and high pressure is also applied to the tap conductor by side 63 of the keeper via jaw 9. As regards the latter, it will be observed that when side 63 of the keeper applies pressure to jaw 9, bolt 11 is free to move upward in hole 39 to permit side 63 of the keeper to apply pressure to jaw 9 and thence to the tap conductor T. This pressure augments the initial grip of the jaw 9 on the tap conductor which resulted from turning nut 13 to draw up jaw 9. This completes the installation, and the hot stick is removed.
If the lineman should inadvertently apply excessive torque in turning the eyebolt 7, the eye 71 of the eyebolt will simply shear off at the weakened juncture 84 of the eye and the hexagonal head 75. The head 75 remains in place at the lower end of the shank 79 of the eyebolt and becomes readily accessible, on shearing off of the eye, for application of a wrench mounted on a hot stick to back off the bolt (i.e., screw it down) for removal of the clamp from the main conductor (without having to cut it off the main conductor). Without this feature, overtorquing of the eyebolt might result in failure of one or more of the clamp components, with the dangerous possibility that the clamp may then fall off the main conductor, or else remain on the line with resultant impossibility of removing it from the main conductor without cutting it off.
As will appear from FIG. 9, the clamp 1 provides for high pressure electrical contact not only as between the clamp parts and the main conductor M but also between the clamp parts and the tap conductor T. Also, current is conducted from the main conductor M (the hot line) to the tap conductor T not only via the body 3 of the clamp but also via the keeper 5 (and the jaw 9) so that the clamp is of the "double-bridge" type for better conduction of current to the tap conductor. In addition, the direction of takeoff of the tap conductor is in a plane perpendicular to the direction of length of the main conductor and angled downward and outward from the clamp e.g. toward a transformer), as is preferable to the tap conductor being taken off parallel to the main conductor. Further, the threads in the bore 31 and at 83 on the eyebolt 7 are protected from electrical arc and environmental conditions.
Another feature to be noted is that the location of bolt 11 and nut 13 is such as to provide a safeguard against a lineman applying excessive torque to the nut 13. In this regard, the location of these elements alongside the dome 29 is such that 360° swing of a wrench to turn the nut is prohibited. This means that a lineman is compelled to turn the nut in increments, which makes it improbable that he will apply excessive torque.
Referring to FIGS. 10-15, there is shown a second version of the hot line clamp of this invention, designated in its entirety by the reference character 101, which incorporates means for automatic initial gripping of the tap conductor T in the clamp without any necessity for turning a nut or similar initial gripping operation. The clamp 101, as shown, comprises a body 103, a keeper 105, and means indicated at 107 for effecting clamping movement of the keeper relative to the body. Also associated with the body is an auxiliary clamp element 109 constituted by a pivoted one-way gripper having pivot pins or lugs 111 extending from opposite sides thereof, this gripper 109 being interposed between the keeper and the body and being adapted for automatically initially clamping the tap conductor T against the body independently of the keeper simply upon insertion of the end of the tap conductor between the gripper and the body and to resist pulling out of the tap conductor. The keeper 105, when moved in clamping direction by means 107 to clamp the main and tap conductors M and T, engages pins 111 of gripper 109 and acts via the latter to apply clamping pressure to the tap conductor augmenting the initial grip of gripper 109 on the tap conductor.
More particularly, the body 103 has a central section 113 having a sidewall 115 and end walls 117. The end walls have downwardly extending outwardly offset extensions 119. The central section per se is open at the top. A jaw 121 similar to jaw 33 extends laterally outward from sidewall 115, this jaw being formed with a downwardly opening groove 123 for receiving the main conductor. A hollow jaw formation 125 extends laterally outward from the side of central section 113 opposite the sidewall 115, this formation having a top wall 127, a downwardly and outwardly angled outer wall 129 of trough shape in cross section, and sidewalls 131. Jaw formation 125 is open at the bottom and open at its inner end to the cavity 133 defined by sidewall 115 and end walls 117 of the center section. Extensions 119 of the end walls have tongues 135 extending from the edges thereof opposite the jaw 121. The inside faces of these tongues are coplanar with the inside faces of extensions 119; however, the tongues are thicker than extensions 119. The tongues have grooves 137 along their inside upper edges.
The keeper 105 is essentially the same as keeper 5 above described, and parts thereof corresponding to those of keeper 5 are designated by the same reference numerals as applied to parts of the keeper 5 with these numerals primed. Keeper 105 has a notch 139 at its tap conductor side, and the pins 65' of keeper 105 which extend outward at this side are adapted to ride in the grooves 137 in tongues 135.
The means 107 for effecting clamping movement of the keeper relative to the body 103 comprises a bolt 141 extending downward from the top of the body and an eyenut 143 threaded on the bolt. The latter has a head 145 seated on the upper rim of central section 113 of the body, a U-shaped shank 147 extending down from the head and a threaded stem 149 extending down from the center of the bottom of the U-shaped shank. The head has recesses 151 formed in its top at opposite sides thereof, and is held in place by tangs 153 formed integral with the body 103 bent over into these recesses. The eyenut 143 comprises an eye 155 having a stem 157 joined to the lower end of a hexagonal head 159 (like head 75), the stem having annular groove 161 (corresponding to groove 84). Head 159 has a circular flange 163 at its upper end (corresponding to flange 77). A circular stem 165 extends upward from flange 163, this stem 165 having a collar 167 at its upper end (corresponding to collar 81). A threaded bore 169 extends down from the upper end of stem 165 into the head 159.
The gripper 109, as shown, is a one-way or self-locking gripper generally of semicircular outline, having a grooved semicircular periphery 171 which is preferably knurled or otherwise roughened for a good friction grip on the inserted end of the tap conductor. The gripper pivot pins 111, which are formed integrally with the gripper, extend out from opposite sides of the gripper on an axis offset from the axis of the semicircular gripper periphery, and are engaged against curved end formations 173 on the keeper 105 at opposite sides of the notch 139 in the keeper. The pins 111 extend out over the tongues 135 of the body 103, and one of them has a lever arm 175 at its outer end. The gripper extends up into the hollow jaw formation 125 between the side walls 131 of the latter, its grooved semicircular periphery 171 being swingable toward and away from the tap conductor groove 177 in the trough-shaped downwardly angled outer wall 129 of the jaw formation 125, which acts as a fixed clamp jaw in conjunction with the gripper. A spring 179 biases the gripper 109 to swing in clamping direction toward the wall 129 (clockwise as viewed in FIG. 13), and the gripper is adapted to swing in opening direction (counterclockwise as viewed in FIG. 13) against the bias of the spring. The spring 179, as shown, is a torsion spring, coiled around one of the gripper pivot pins 111 and having one end locked to the keeper 105 and its other end hooked to the gripper 109. Thus, it not only functions to bias the gripper to swing in clamping direction, but also maintains the gripper in assembly with the keeper. The notch 139 in the keeper provides clearance for the gripper to swing, and it will also be noted that when the gripper swings back, it extends into the space bounded by the U-shaped shank 147 extending down from head 145 of the bolt 141. A washer 181 is seated on the flange 163. Arm 175 is useful to turn the gripper 109 to release the tap conductor from the clamp after the clamp has been removed from the main conductor, being manually operated for this purpose.
With the eyenut 143 backed down on bolt 141 so that keeper 105 is in an open retracted position, the end of the tap conductor T is simply entered between the gripper 109 and groove 175, with resultant swinging back of the gripper while it continues to be biased in clamping direction by the torsion spring 179. Upon such entry of the end of the tap conductor between gripper 109 and groove 177, any tendency of the tap conductor to pull out results in tighter clamping of the tap conductor by the gripper, so that it is prevented from pulling out when the clamp 101 is subsequently applied to the main conductor M. After the clamp 101 has been applied to the main conductor (in a manner similar to that described for clamp 1), the eyenut 143 is rotated by a hot stick to cause the eyenut to be drawn up on bolt 141 and thereby move the keeper 105 upward to effect clamping of the main conductor M and application of pressure from the keeper 105 to the gripper 109 for augmented high pressure clamping of the end of the tap conductor T by the gripper in the groove 177.
In view of the above, it will be seen that the several objects of the invention are achieved and other advantages results attained.
As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.
This invention relates to hot line clamps, i.e., a clamp for connection of a tap conductor to a main conductor (the "hot line") in an electric power distribution system.
The invention is particularly concerned with improvements on hot line clamps of the general type shown in such U.S. Pat. Nos. as 2,651,766, 2,867,787, 3,075,166, 3,177,459 and 3,142,525, adapted for initial application to the clamp of a tap conductor, and application of the clamp with the tap conductor connected thereto to a hot line by use of a hot stick. One of the problems involved in such clamps is that of attaining high pressure electrical contact between the clamp parts and the conductors, particularly the tap conductor, while permitting easy initial application of the tap conductor to the clamp in such manner as to prevent pullout of the tap conductor while the clamp is being applied to the hot line. In the clamps such as shown in the last four patents mentioned above, the end of the tap conductor is both initially and finally clamped by means of a tap conductor clamping bolt or screws wholly independently of the main clamping bolt of the clamp, and while this may provide for an initial firm grip on the tap conductor, it may not always provide for maintenance of high pressure electrical contact between the clamp parts and the tap conductor, due, for example, to relaxation of the grip of the tap conductor clamping bolt or screws on the tap conductor. As regards the hot line clamp shown in U.S. Pat. No. 2,651,766, for example, while the tap conductor as well as the main conductor are ultimately both pressured by the keeper, the initial grip of the tap conductor is simply by spring action, and this may not be sufficient to prevent the tap conductor from pulling out when the clamp is being applied to the hot line. Another problem involved in clamps such as described arises from the possibility that a lineman may in certain instances apply excessive torque to the bolt while the clamp is being installed on the hot line, causing mechanical failure of the clamp such that it may fall off the hot line. In some instances a clamp which has failed because of overtorquing may remain on the hot line, rather than falling off, and it is then desirable to remove it to avoid a cluttered appearance, but removal of failed prior clamps has heretofore been impossible without cutting them from the hot line.
SUMMARY OF THE INVENTION
Among the several objects of this invention may be noted the provision of an improved hot line clamp which provides for better electrical interconnection of the main and tap conductors via sustained high pressure electrical contact between the clamp parts and the conductors, also providing for a firm grip on the tap conductor initially effectively to prevent it from pulling out of the clamp when the clamp is applied to the hot line; the provision of such a clamp wherein current is conducted from the main conductor to the tap conductor via both the body of the clamp and a keeper of the clamp so that the clamp is of the "double-bridge" type; the provision of such a clamp which is adapted to remain clamped on the main conductor in the event it is subjected to excessive torque when being applied to the main conductor, and which, in the event of such overtorquing, can be readily removed without having to cut it off the main conductor; the provision of such a clamp wherein the direction of takeoff of the tap conductor from the clamp is in a plane perpendicular to the direction of length of the main conductor and angled downward and outward from the clamp, as is preferable to the direction of takeoff of the tap conductor being parallel to the main conductor; the provision of such a clamp in which the thread on the clamp bolt and the thread in the clamp body are protected from both electrical arc and environmental conditions; and the provision of such a clamp adapted for automatic initial gripping of the tap conductor.
In general, a hot line clamp of this invention comprises a clamp body, a keeper for clamping a main conductor and a tap conductor against the body, means for effecting clamping movement of the keeper, an auxiliary clamp element interposed between the keeper and the body for initially clamping the tap conductor against the body, and means for effecting clamping movement of the auxiliary clamp element independently of the means for effecting clamping movement of the keeper initially to grip the conductor. With this arrangement, the keeper, when moved in clamping direction, engages the auxiliary clamping element and acts via the latter to apply clamping pressure to the tap conductor augmenting the initial grip of the auxiliary clamp element on the tap conductor for sustained high pressure electrical contact as between the body, the keeper and the tap conductor as well as between the body, the keeper and the main conductor. Other objects and features will be in part apparent and in part pointed out hereinafter.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a view in elevation of a hot line clamp of this invention, taken in the direction of the length of a main conductor on which the clamp is applied, and showing the clamp in an opened position;
FIG. 2 is a plan of FIG. 1;
FIG. 3 is a right side elevation of FIG. 1;
FIG. 4 is a left side elevation of FIG. 1;
FIG. 5 is a section on line 5--5 of FIG. 1;
FIG. 6 is a section on line 6--6 of FIG. 3;
FIG. 6A is a view showing a modified type of eyebolt for the FIG. 1 clamp;
FIG. 7 is a section on line 7--7 of FIG. 1;
FIG. 8 is a section on line 8--8 of FIG. 1;
FIG. 9 is a section similar to FIG. 6 but showing the clamp closed on a main conductor and a tap conductor;
FIG. 10 is a view in elevation of another embodiment of the hot line clamp of this invention, taken (like FIG. 1) in the direction of the length of a main conductor on which the clamp is applied, and showing the clamp in an opened position;
FIG. 11 is a plan of FIG. 10;
FIG. 12 is a right side elevation of FIG. 10;
FIG. 13 is a section on line 13--13 of FIG. 12;
FIG. 14 is a section on line 14--14 of FIG. 10; and
FIG. 15 is a view similar to FIG. 10 but showing the clamp closed on a main conductor and a tap conductor.
Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIGS. 1-9 of the drawings, a first version of the hot line clamp of this invention is designated in its entirety by the reference numeral 1. As shown therein, the clamp 1 comprises a clamp body 3, which may be cast of a suitable electrically conductive metal such as aluminum or bronze. Associated with the body 3 is a keeper 5 for effecting gripping of the clamp on a main conductor M and gripping to the clamp of a tap conductor T. At 7 is indicated means constituted by an eyebolt for effecting clamping movement of the keeper relative to the body to clamp the main and tap conductors against the body. Also associated with the body is an auxiliary clamp element 9 constituted by a jaw at the lower end of a bolt 11, this element or jaw 9 being interposed between the keeper and the body and being adapted for initially clamping the tap conductor T against the body independently of the keeper. The bolt 11 is disposed completely on one side of each of a pair of perpendicularly disposed reference planes intersecting at an axis of the eyebolt 7 and represented respectively by the lines 5--5 in FIG. 1 and 6--6 in FIG. 3, and the auxiliary clamp element 9 is bisected by the reference plane represented by line 6--6 in FIG. 3. Means for effecting clamping movement of the auxiliary clamp element 9 independently of the eyebolt 7 is shown to constitute a nut 13 threaded on the bolt 11. The keeper 5, when moved in clamping direction by the eyebolt 7 to clamp the main and tap conductors M and T, engages the auxiliary clamp element 9 and acts via the latter to apply clamping pressure to the tap conductor augmenting the initial grip of element 9 on the tap conductor.
More particularly, the body 3 has a central portion 15 having a top wall 17, sidewalls 19 and 21, and end walls 23. The sidewall 19 extends down from the top wall somewhat farther than the sidewall 21. The end walls 23 extend down from the top wall somewhat farther than the sidewall 19. The central portion 15 of the body is formed with a relatively wide internal web 25 extending down from the top wall somewhat farther than the sidewall 19 spanning the sidewalls 19 and 21 and located generally centrally between the end walls 23. This leaves a pair of recesses 27 between the internal web 25 and the end walls, these recesses opening downward. The central portion 15 of the body is also formed with a dome-shaped boss 29 extending upward from the top wall 17 in alignment with the internal web 25. A tapped hole 31 extends upward from the bottom of the internal web 25 into the boss 29, terminating short of the upper end of the boss so that the latter is closed at the top for protection of the thread in the hole. This hole is slightly offset from the center of length of the web 25 toward the sidewall 19.
A jaw 33 extends laterally outward from sidewall 19 of the central portion 15 of body 3, this jaw being angled outward and downward from sidewall 19. It is formed with a downwardly opening groove 35 for receiving the main conductor M. End walls 23 of the central portion 15 of body 3 are notched as indicated at 37 at the ends of groove 35 for receiving the main conductor.
A jaw formation 39 extends laterally outward from the sidewall 21 of the central portion 15 of the body 3. This jaw formation 39 has an upper portion 41 angled downward from the body 3 formed with a downwardly facing groove 43 for receiving the tap conductor T. It also has an outer end portion 45 extending downward from the outer end of upper portion 41 formed with a downwardly opening slot 47. End portion 45 is spaced laterally outward from the sidewall 21 of the central portion 15 of the body 3, forming a downwardly opening channel 49 extending horizontally endwise in respect to the body on the opposite side thereof from the main conductor groove 35 (this channel 49 extending parallel to the main conductor groove 35). The jaw formation 39 has a bolt hole 51 in the top thereof toward one end of the body, this hole being located alongside the tap conductor groove 43. The latter groove extends at right angles to the main conductor groove 35. The body 3 also has a pair of tongues 53 extending downward from the ends of the sidewall 21 of its central portion 15. These tongues are initially formed to extend vertically downward, but are subsequently bent to an angled position as shown in FIG. 1 for a purpose that will appear.
The keeper 5, which like the body 3 is cast of a suitable electrically conductive metal such as aluminum or bronze, has an arcuate bottom wall 55, the width of which is slightly less than the spacing of the tongues 53 and the end walls 23 of central portion 15 of the body so as to have a loose fit therebetween. The keeper 5 has upwardly extending end walls 57 at the ends of its arcuate bottom wall, these end walls having upwardly projecting tongues 59 adapted for reception in the recesses 27 in the central portion 15 of body 3. The keeper is formed at one side thereof with a jaw 61 for clamping the main conductor M in the groove 35 and is adapted for engagement of its other side 63 with the auxiliary clamp element 9, as will appear. Jaw 61 has portions 61a extending beyond the keeper end walls 57, the length of jaw 61 corresponding to the length of the main conductor groove 35. Lugs or pins 65 extend outward from the keeper end walls 57 at its said other side. The arcuate bottom wall 55 of the keeper is formed with a slot 67 for the eyebolt 7, this slot being in the form of a keyhole slot having an enlarged section 67a toward side 63 of the keeper. The keeper also has a pair of lugs 69 extending downward at opposite ends thereof, these lugs being offset outward from the keeper end walls 57.
The eyebolt 7 (which may also be formed of an electrically conductive metal such as bronze) comprises an eye 71 having a stem 73 joined to one end (the lower end) of hexagonal head 75. This head has a circular flange 77 at its other (upper) end. The shank 79 of the eyebolt extends upward from this flange. The shank 79 has a diameter slightly less than the width of the smaller portion of the keyhole slot in the keeper. It is formed with an integral circular collar 81 spaced from flange 77, this collar having a diameter larger than the width of the smaller portion of the keyhole slot 67 but smaller than the width of the enlarged portion 67a of the keyhole slot. The shank is threaded at its upper end as indicated at 83 for being threaded in the tapped hole 31 in the body 3. The stem 73 has an annular groove 84 at its juncture with the head 75, to provide a weakened juncture adapted to fail in shear if the eyebolt is overtorqued.
The bottom portion of the threads on the threaded upper end 83 of shank 79 of the eyebolt are interrupted as indicated at 83a, the interruptions being constituted by grooves extending upward from the lower end of the threaded end portion 83 a distance somewhat less than the length of portion 83. These interruptions or grooves 38a provide for relief in the portion 83 to remove any foreign material such as dust or particles of grit that may accumulate in the threads in hole 31 of the body 3 during service. When the eyebolt 7 is rotated in the direction to open clamp, the body threads are wiped clean to prevent galling or jamming of the threads.
FIG. 6A illustrates a modified type of eyebolt 7a which may be used instead of the eyebolt 7. This differs from the eyebolt 7 essentially only in that it has a head in the form of a second eye 75a above the eye 71 instead of the hexagonal head 75, with the shear failure groove 84 between these eyes. The provision of eye 75a permits a lineman to remove the clamp from the main conductor without the use of a wrench adapter on his hot line stick, if the primary eye 71 should shear off during installation.
As previously mentioned, the auxiliary clamp element 9 is constituted by a jaw at the lower end of a bolt 11. This bolt 11 has a generally cylindric head 85 at one end constituting its lower head. The auxiliary clamping element of jaw 9 is formed integrally with head 85 at one side thereof. As shown best in FIGS. 7 and 9, it is of generally triangular form, having an inclined upper surface 87, a vertical surface 89, and a bottom 91. The upper surface 87 is formed with a groove 93 extending lengthwise thereof, and the bottom is formed with a groove 95 extending transversely thereof (i.e., groove 95 extends transversely with respect to groove 93). The slope of surface 87 (and groove 93) matches the slope of the tap conductor groove 43 in the body 3. The bolt 11 and jaw 9 integral therewith are preferably formed of a suitable electrically conductive metal such as bronze.
As previously noted, the tongues 53 are initially formed to extend vertically downward from the body 3. With the tongues 53 in this initial condition, the parts are assembled as follows:
The bolt 11 is inserted upward through hole 51, with the jaw 9 in position transverse to the clamp body 3 (i.e., in a plane at right angles to the plane of the main conductor groove 35), and with the grooved upper surface 87 of the jaw 9 opposed to the downwardly facing tap conductor groove 43 in the clamp body. The toe of the jaw 9 extends into the slot 47 and is vertically slidable in the slot 47. The grooved bottom 91 of jaw 9 lines up with the channel 49. A spring washer 97 and nut 13 are applied to the upper end of the bolt. A washer 99 having an internal diameter larger than that of collar 81 is applied to the shank 79 of the eyebolt 7, bearing against flange 77 on the hexagonal head 75 of the eyebolt, and the keeper 5 is applied to the shank of the eyebolt by passing collar 81 through the enlarged portion 67aa of the keyhole slot 67 in the arcuate bottom wall 55 of the keeper. The lugs 69 which extend downward from the keeper straddle the washer 99 and flange 77. The threaded upper end 83 of the eyebolt is then threaded in the tapped hole 31 in the clamp body 3, the jaw 61 of the keeper being opposed to the main conductor groove 35 in the body, and the side 63 of the keeper being registered with the channel 49 in the body, the pins 65 of the keeper being slidable on the surfaces of tongues 53 which face outward toward the end portion 45 of jaw formation 39. Then the tongues 53 are bent laterally outward in the direction toward end portion 45 of jaw formation 39 to hold the keeper and eyebolt captive to the body 3 (see FIGS. 1, 6 and 9 showing the tongues so bent).
The clamp 1 is utilized by a lineman in the following manner:
With the eyebolt 7 and nut 13 backed off as shown in FIGS. 1, 6 and 7, so that the keeper 5 is in an open retracted position and so that the jaw 9 is in an open retracted position with respect to the grooved fixed jaw portion 41 of the body 3, the end of the tap conductor T is entered between jaw 9 and fixed jaw portion 41, and nut 13 is turned to draw up the bolt 11 and the jaw 9 so that the end of the tap conductor is clamped in groove 43 of the body 3 by jaw 9. The nut 13 is turned to draw up jaw 9 for initial clamping of the tap conductor with sufficient grip to prevent the tap conductor from pulling out when the clamp 1 is subsequently applied to the main conductor M.
With the tap conductor T so gripped in the clamp 1, the latter is mounted on the end of a lineman's hot stick, the usual hook on the hot stick being entered in the eye 71 of eyebolt 7, the hot stick being activated to draw the lugs 69 of the keeper 5 into the head of the hot stick for stabilizing the clamp on the hot stick. The hot stick is then used to apply the clamp 1 to the main conductor, by hooking jaw 33 over the main conductor, the latter being accommodated in the groove 35. The hot stick is then pulled downward to disengage the lugs 69 from the hot stick head, so that the hot stick may be rotated to turn the eyebolt 7, and the hot stick is then rotated to turn the eyebolt in the direction to cause the eyebolt to be drawn upward relative to the clamp body 3 (by the threading of the threaded upper end 83 of the eyebolt into the threaded bore 31).
The keeper 5 (which bears against washer 99 on flange 77 of the eyebolt) moves upward relative to body 3 along the eyebolt to the point where jaw 61 of the keeper engages the main conductor M or the side 63 of the keeper engages jaw 9. On continued upward movement of the keeper by turning of the eyebolt, the keeper rocks relative to the eyebolt (as permitted by the arcuate form of the bottom wall 55 of the keeper and the play of the keeper with respect to the eyebolt permitted by slot 67) so that contact is established not only between jaw 61 of the keeper and the main conductor M but also between side 63 of the keeper and jaw 9. Turning of the eyebolt is continued after this double contact has been established so that high pressure is applied to the main conductor by jaw 61 of the keeper and high pressure is also applied to the tap conductor by side 63 of the keeper via jaw 9. As regards the latter, it will be observed that when side 63 of the keeper applies pressure to jaw 9, bolt 11 is free to move upward in hole 39 to permit side 63 of the keeper to apply pressure to jaw 9 and thence to the tap conductor T. This pressure augments the initial grip of the jaw 9 on the tap conductor which resulted from turning nut 13 to draw up jaw 9. This completes the installation, and the hot stick is removed.
If the lineman should inadvertently apply excessive torque in turning the eyebolt 7, the eye 71 of the eyebolt will simply shear off at the weakened juncture 84 of the eye and the hexagonal head 75. The head 75 remains in place at the lower end of the shank 79 of the eyebolt and becomes readily accessible, on shearing off of the eye, for application of a wrench mounted on a hot stick to back off the bolt (i.e., screw it down) for removal of the clamp from the main conductor (without having to cut it off the main conductor). Without this feature, overtorquing of the eyebolt might result in failure of one or more of the clamp components, with the dangerous possibility that the clamp may then fall off the main conductor, or else remain on the line with resultant impossibility of removing it from the main conductor without cutting it off.
As will appear from FIG. 9, the clamp 1 provides for high pressure electrical contact not only as between the clamp parts and the main conductor M but also between the clamp parts and the tap conductor T. Also, current is conducted from the main conductor M (the hot line) to the tap conductor T not only via the body 3 of the clamp but also via the keeper 5 (and the jaw 9) so that the clamp is of the "double-bridge" type for better conduction of current to the tap conductor. In addition, the direction of takeoff of the tap conductor is in a plane perpendicular to the direction of length of the main conductor and angled downward and outward from the clamp e.g. toward a transformer), as is preferable to the tap conductor being taken off parallel to the main conductor. Further, the threads in the bore 31 and at 83 on the eyebolt 7 are protected from electrical arc and environmental conditions.
Another feature to be noted is that the location of bolt 11 and nut 13 is such as to provide a safeguard against a lineman applying excessive torque to the nut 13. In this regard, the location of these elements alongside the dome 29 is such that 360° swing of a wrench to turn the nut is prohibited. This means that a lineman is compelled to turn the nut in increments, which makes it improbable that he will apply excessive torque.
Referring to FIGS. 10-15, there is shown a second version of the hot line clamp of this invention, designated in its entirety by the reference character 101, which incorporates means for automatic initial gripping of the tap conductor T in the clamp without any necessity for turning a nut or similar initial gripping operation. The clamp 101, as shown, comprises a body 103, a keeper 105, and means indicated at 107 for effecting clamping movement of the keeper relative to the body. Also associated with the body is an auxiliary clamp element 109 constituted by a pivoted one-way gripper having pivot pins or lugs 111 extending from opposite sides thereof, this gripper 109 being interposed between the keeper and the body and being adapted for automatically initially clamping the tap conductor T against the body independently of the keeper simply upon insertion of the end of the tap conductor between the gripper and the body and to resist pulling out of the tap conductor. The keeper 105, when moved in clamping direction by means 107 to clamp the main and tap conductors M and T, engages pins 111 of gripper 109 and acts via the latter to apply clamping pressure to the tap conductor augmenting the initial grip of gripper 109 on the tap conductor.
More particularly, the body 103 has a central section 113 having a sidewall 115 and end walls 117. The end walls have downwardly extending outwardly offset extensions 119. The central section per se is open at the top. A jaw 121 similar to jaw 33 extends laterally outward from sidewall 115, this jaw being formed with a downwardly opening groove 123 for receiving the main conductor. A hollow jaw formation 125 extends laterally outward from the side of central section 113 opposite the sidewall 115, this formation having a top wall 127, a downwardly and outwardly angled outer wall 129 of trough shape in cross section, and sidewalls 131. Jaw formation 125 is open at the bottom and open at its inner end to the cavity 133 defined by sidewall 115 and end walls 117 of the center section. Extensions 119 of the end walls have tongues 135 extending from the edges thereof opposite the jaw 121. The inside faces of these tongues are coplanar with the inside faces of extensions 119; however, the tongues are thicker than extensions 119. The tongues have grooves 137 along their inside upper edges.
The keeper 105 is essentially the same as keeper 5 above described, and parts thereof corresponding to those of keeper 5 are designated by the same reference numerals as applied to parts of the keeper 5 with these numerals primed. Keeper 105 has a notch 139 at its tap conductor side, and the pins 65' of keeper 105 which extend outward at this side are adapted to ride in the grooves 137 in tongues 135.
The means 107 for effecting clamping movement of the keeper relative to the body 103 comprises a bolt 141 extending downward from the top of the body and an eyenut 143 threaded on the bolt. The latter has a head 145 seated on the upper rim of central section 113 of the body, a U-shaped shank 147 extending down from the head and a threaded stem 149 extending down from the center of the bottom of the U-shaped shank. The head has recesses 151 formed in its top at opposite sides thereof, and is held in place by tangs 153 formed integral with the body 103 bent over into these recesses. The eyenut 143 comprises an eye 155 having a stem 157 joined to the lower end of a hexagonal head 159 (like head 75), the stem having annular groove 161 (corresponding to groove 84). Head 159 has a circular flange 163 at its upper end (corresponding to flange 77). A circular stem 165 extends upward from flange 163, this stem 165 having a collar 167 at its upper end (corresponding to collar 81). A threaded bore 169 extends down from the upper end of stem 165 into the head 159.
The gripper 109, as shown, is a one-way or self-locking gripper generally of semicircular outline, having a grooved semicircular periphery 171 which is preferably knurled or otherwise roughened for a good friction grip on the inserted end of the tap conductor. The gripper pivot pins 111, which are formed integrally with the gripper, extend out from opposite sides of the gripper on an axis offset from the axis of the semicircular gripper periphery, and are engaged against curved end formations 173 on the keeper 105 at opposite sides of the notch 139 in the keeper. The pins 111 extend out over the tongues 135 of the body 103, and one of them has a lever arm 175 at its outer end. The gripper extends up into the hollow jaw formation 125 between the side walls 131 of the latter, its grooved semicircular periphery 171 being swingable toward and away from the tap conductor groove 177 in the trough-shaped downwardly angled outer wall 129 of the jaw formation 125, which acts as a fixed clamp jaw in conjunction with the gripper. A spring 179 biases the gripper 109 to swing in clamping direction toward the wall 129 (clockwise as viewed in FIG. 13), and the gripper is adapted to swing in opening direction (counterclockwise as viewed in FIG. 13) against the bias of the spring. The spring 179, as shown, is a torsion spring, coiled around one of the gripper pivot pins 111 and having one end locked to the keeper 105 and its other end hooked to the gripper 109. Thus, it not only functions to bias the gripper to swing in clamping direction, but also maintains the gripper in assembly with the keeper. The notch 139 in the keeper provides clearance for the gripper to swing, and it will also be noted that when the gripper swings back, it extends into the space bounded by the U-shaped shank 147 extending down from head 145 of the bolt 141. A washer 181 is seated on the flange 163. Arm 175 is useful to turn the gripper 109 to release the tap conductor from the clamp after the clamp has been removed from the main conductor, being manually operated for this purpose.
With the eyenut 143 backed down on bolt 141 so that keeper 105 is in an open retracted position, the end of the tap conductor T is simply entered between the gripper 109 and groove 175, with resultant swinging back of the gripper while it continues to be biased in clamping direction by the torsion spring 179. Upon such entry of the end of the tap conductor between gripper 109 and groove 177, any tendency of the tap conductor to pull out results in tighter clamping of the tap conductor by the gripper, so that it is prevented from pulling out when the clamp 101 is subsequently applied to the main conductor M. After the clamp 101 has been applied to the main conductor (in a manner similar to that described for clamp 1), the eyenut 143 is rotated by a hot stick to cause the eyenut to be drawn up on bolt 141 and thereby move the keeper 105 upward to effect clamping of the main conductor M and application of pressure from the keeper 105 to the gripper 109 for augmented high pressure clamping of the end of the tap conductor T by the gripper in the groove 177.
In view of the above, it will be seen that the several objects of the invention are achieved and other advantages results attained.
As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.