US 3363219 A
Description (OCR text may contain errors)
Jan. 9, 1968 D. c. HUBBARD ETAL 3,
ELECTRICAL CLAMP HAVING SCRAPER CONTACT Filed July 15, 1965 0 INVENTORS. 3 David C. Hubbard James Thomas Odom United States Patent 3,363,219 ELECTRICAL CLAMP HAVING SCRAPER CONTACT David C. Hubbard and James Thomas Odom, Centralia, Mo., assignors to A. B. Chance Company, Centralia, Mo., a corporation of Missouri Filed July 15, 1965, Ser. No. 472,260 3 Claims. (Cl. 33995) This invention relates to a safety ground clamp particularly adapted for use in connecting high voltage electrical lines to a grounded supporting tower during maintenance and repair operations.
In order to provide for the safety of linemen during repair of high voltage transmission lines, it is the practice to ground the lines under repair to the metal tower which supports the lines in spaced relationship to the ground. This is to preclude the possibility of injury to linemen should the lines be inadvertently re-energized before the repair operation has been completed.
The customary procedure is for the lineman to electrically connect the lines under repair to the body of a clamp which is, in turn, secured to one of the structural members of the supporting tower. Because of the extremely high currents involved should re-energization occur, it is requisite that the contact between the clamp and the tower member present negligible resistance to the flow of electric current. Otherwise, disintegration of the clamp would occur at the point of contact with the tower member, resulting in interruption of the current path to ground which, of course, would present an extremently hazardous condition to personnel.
Since the surfaces of the structural members of supporting towers are frequently coated with oxides and other contaminants which preclude the establishment of a low resistance electrical connection, such coatings must be removed to eliminate the hazard of high resistance ground connections.
It is, therefore, the primary object of this invention to provide an electrical connector having a surface abrading contact face which is movable during installation of the connector to remove oxides and contaminants on the surface to be gripped by the connector, thereby providing a low resistance electrical connection.
Another object of this invention is to provide an electrical connector as aforesaid wherein the current path from the line to the contact face is achieved by a direct mechanical connection without the use of movable contact faces.
Still another object of the instant invention is to provide a connector as set forth above having resilient pressure-applying means which maintains sustained contact pressure in the event of movement of the connector during electrical stress, normal pressure relaxation, or minor melting of the scrubbing points by current flow therethrough.
A further object of the invention is to provide a connector as aforesaid having a handle rigidly coupled with the contact face to impart the scrubbing action thereto, which handle also serves as a terminal for connecting an electrical line to the connector.
Other objects will become apparent as the detailed description proceeds.
In the drawing:
FIGURE 1 is an elevational view of the connector clamp illustrating the same in clamping engagement with an angle member of a support tower;
FIG. 2 is a bottom view of the connector;
FIG. 3 is an enlarged, detailed view of the scrubber face taken along line 33 of FIG. 1; and
FIG. 4 is a vertical sectional view taken along line 4-4 of FIG. 3.
The numeral 10 designates a C-shaped body having a pair of spaced-apart legs 12 and 14. Leg 12 is somewhat shorter in length than leg 14 and threadably receives a pressure member 16 in the form of a screw 17 provided with a T-shaped handgrip 18. Leg 14 has a transverse opening 20 therethrough (FIG. 4) in axial alignment with pressure member 16. Opening 20 receives a rotatable anvil 22 having a cylindrical shank 24 terminating in a head 26.
Head 26 is provided with two sets of concentric, arcuate ridges 28 and 30, each set of ridges comprising four arcuate segments separated by notches 32. It will be appreciated in FIG. 4 that the ridges 28 and 30 are toothed-shape and present cutters, the cutting action of the ridges being enhanced by the presence of the notches 32.
A pair of opposed compression washers 34 are disposed between head 26 and the inner surface 36 of leg 14. The end of shank 24 remote from head 26 has a transverse aperture 38 therein which receives a pin 40 extending through a split clamp 42. A drawbolt 44 maintains the split clamp rigid with shank 24, pin 40 serving to positively preclude rotation of clamp 42 relative to shank 24. The split clamp forms one end of a handle 46 which extends away from the clamp at approximately a 45 angle as illustrated.
The central portion of handle 46 comprises an internally threaded enlargement 48 which receives the threaded end of a cable ferrule 50, a pin 52 being utilized to rigidly interconnect the end of the ferrule and the enlargement. Ferrule is utilized to connect the free end of handle 46 to an electrically conductive cable 54 which, in a typical application of the instant invention, is utilized as a lead to electrically connect the handle to a high voltage transmission line.
An angle retainer 56 is secured to the end of leg 14 by a thumbscrew 58, retainer 56 being illustrated in engagement with an angle member 60 which represents a structural member of a high voltage transmission line support tower. The connector is secured to the angle member by advancing the rotatable screw 17 toward the contact face presented by ridges 28 and 30 to clamp the member between screw 17 and head 26.
In use, handgrip 1-8 is rotated to advance screw 17 until the angle member 60 is clamped between the screw and the contact face of head 26 with suflicient force to fn'ctionally engage the ridges 28 and 30 with the surface of the angle member. Handle 46 is then gripped by the operator and manipulated as illustrated in FIG. 2 to rotate shank 24 about its longitudinal axis. Preferably, a back and forth swinging motion is imparted to handle 46 to effect a scrubbing or scraping action at the surface of the angle member in engagement with the scrubber contact face.
It will be appreciated that the notches 32 in the scrubber face assist in providing a cutting action since the notches divide ridges 28 and 30 into cutter segments to more effectively abrade the surface of the angle member. Thus, surface oxides or other contaminants are removed from the member so that the crown of each of the cutting ridges ultimately contacts a clean surface and provides a low resistance electrical connection between shank 24 and the angle member. Although the scrubber face configuration shown is generally preferred, it should be understood that other face configurations could also be employed to produce a satisfactory cleaning action.
After the handle is rotated to scrub the surface of the angle member, handgrip 18 is further advanced until maximum clamping action is obtained and the connector assembly is firmly attached to the angle member such that relative movement of the connector and the member is difficult. Retainer 56 may be utilized to further establish a rigid joining of the connector to the member.
As handgrip 18 is rotated to its maximum pressure poa the utilization of the instant invention since sustained contact pressure is provided to maintain'the low resistance electrical connection should relative movement of the connector and the angle member occur during electrical stress, normal pressure relaxation, or minor melting of the crowns of the cutter segments by current flow there through. In this manner, the compressed washers provide an additional margin of safety which, of course, is vital in the utilization of the instant invention as a means of preventing injury to linemen in the event of inadvertent re-energization of transmission lines during repair and maintenance operations. 7
It should also be noted that the contact path provided by the invention from the scrubber face to cable 54 comprises a unitary, electrically conductive structure after .assembly of the components of handle 46 and joining of the handle with shank 24. Therefore, electrical continuity is established via a direct mechanical connection without the use of movable contact faces which would create additional problems of surface contamination and high resistance points.
Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:
1. An electrical connector comprising:
a body having a pair of spaced legs;
an electrically conductive anvil rotatably carried by one of said legs;
pressure means carried by the other of said legs and movable toward the anvil for clamping a conductive component between the pressure means and the anvil;
an electrically conductive handle rigid with said anvil and extending therefrom for rotating the anvil,
said handle being provided with means for coupling the handle with a current-carrying line; and
means on the anvil for scrubbing said component when the latter is held between the pressure means and the anvil and upon rotation of the anvil by the handle, whereby to provide a low resistance electrical connection with said component by removal of surface oxides or other contaminants.
2. An electrical connector comprising:
a body having a pair of spaced legs;
an electrically conductive anvil rotatably carried by one of said legs and having a shank terminating in a head;
pressure means carried by the other leg for movement toward and away from the anvil,
said one leg having a transverse opening therein aligned with said pressure means and receiving said shank with said head disposed in facing relationship to the pressure means;
a resilient, compressible element between said one leg and said head and biasing the latter toward said pressure means;
an electrically conductive handle rigid with said shank and extending transversely therefrom for rotatingrthe anvil, a
said handle being provided with means for coupling, the
handle with a current-carrying line; and
means on said head for scrubbing a conductive component held between the pressure means and the head during rotation of the latter by said handle, whereby to provide a low resistance electrical connection with said component by removal of surface oxides or other contaminants and to provide sustained contact pressure by compression of said element-upon tightening of said pressure means.
3. The invention of claim 2: V
and a retainer secured to the free end of said one leg for engaging said conductive component to assist in preventing relative movement of the body'and the conductive component when the latter is held between the pressure means and the head, said scrubbing means comprising a plurality of spaced,
arcuate ridges on said head disposed in a circular pattern coaxial with said shank.
References Cited I UNITED STATES PATENTS 1,810,901 6/1931 Bormann et a1; 24-263.3 1,833,462 11/1931 Hagist 15137 f 2,420,895 11/ 1947 Merriman 339264 2,431,439 a 11/ 1947 Williams 339-264 2,659,954 11/1953 Woolsey 24--279 FOREIGN PATENTS 1,102,843 3/ 1961 Germany.
MARVIN A. CHAMPION, Primary Examiner.
I EDWARD c. ALLEN, Examiner.