US2304807A - Hot line jumper clamp - Google Patents

Description

Dec. 15, 1942. J. DONOGHUE ,8

HOTLINE JUMPER CLAMP Filed Jan. 15, 1942 JAMES DONOGHUE,

INVENTOR.

BY 72mm ATTORWQ Patented Dec. 15, 1942 HOT LINE JUMPER CLAMP James Donoghue, Englewood, C'olo., assignor to Lester D. Warwick, Denver, Colo.

Application January 15, 1942, Serial No. 426,881

3 Claims.

This invention relates to improvements in clamps and has reference more particularly to an improved clamp for use in eifecting hot wire jumper connections.

In high voltage transmission, intersecting lines are electrically joined by jumpers that connect the corresponding wires of the two lines. During thunderstorms it frequently happens that some of the jumpers are destroyed due to lightning. When a transmission line is opened as a result of the destruction of one or more jumpers it naturally becomes inoperative until proper electrical connections are reestablished. Since the line or lines carry high voltages, it is evident that great care must be exercised by the lineman when effecting repairs to avoid injury and probable death.

The practice usually followed in replacing destroyed jumpers is to first disconnect that line from the source of voltage and while it is dead are provided at each end with a clamp, usually of the pivoted jaw variety, by means of which the ends of the jumpers can be electrically connected with the wires or cables. Such clamps are quite difiicult to handle and cannot safely i be applied to live high. voltage lines wherefore the latter must be disconnected from the voltage source during repair.

It is the object of this invention to produce an improved clamp for use with high voltage jumpers which shall be so designed and constructed that the jumpers may be-safely applied to live lines thereby avoiding the delay and inconvenience due to the necessity of disconnecting the line.

The above and other objects that may become apparent as this description proceeds are attained by means of a construction and arrangement of parts that will now be described in detail, and for this purpose reference will now be had to the accompanying drawing where the invention has been illustrated and in which:

Figure l is a diagram showing two intersecting transmission lines connected by jumpers;

applied to a transmission line;

Figure 3 is a side elevation of the improved clamp, a portion of the operating means being shown in section;

Figure 4 is a section taken on line 4-4, Figure 1;

Figure 5 is a longitudinal section taken on:line 5-5, Figure 3; and a Figure 6 is a fragmentary section, similar to that shown in Figure 5 but to an enlarged scale.

In the drawing reference numeral l0 designates a pole supporting cross arms H and I2 which carry transmission lines a, b, c and on, In and 01, respectively. The corresponding Wires or cables are found by jumpers a2, b2 and 02. The ends of the jumpers are provided with clamps that have been designated by reference numbers I 3 whose construction has been illustrated in Figures 3 to 6.

The clamp consists of a body member M, usually of circular cross section. The upper end of the body member has an upwardly inclined notch or opening Hi, the material surrounding which forms a hook. The bottom of the hook has been designated by numeral i6 and its point' by numeral ll. It will be observed. that the point projects beyond the line indicating the outer surface of the body, for the purpose of facilitating its attachment to a transmission wire or cable. The rear of the hook, which has been designated by reference numeral I8, is thickened and reenforced so as to resist the clamping strains. It will be observed from Figure 3- that .the rear portion extends beyond the line corresponding to the outer surface of the body. I

The body I4 has an axial threaded opening 19 in which the threaded clamping bolt 20 is Dositioned. The threads on the bolt engage with the threads in the opening and the latter can therefore be moved towards or away from the bottom of the hook by a rotary motion. The upper end of the bolt is provided with a cylindri- 'cal portion 2| of a diameter less than the root diameter of the threads and the upper end has tarial position of the clamp during removal. The Figure 2 illustrates how the clamp may be lower end of the clamping bolt is provided with a cylindrical head 24 having diametrically posi tioned pins 25 whose function will hereinafterappear. A lock nut 25 is positioned on the bolt betweenthe enlarged cylinder head 24 and the end of the body. The lock nut is provided with an upwardly extending projection 21 that overlaps the lower end of the body I 4 in the manner shown quite clearly in Figures 3, 5 and 6. The upper surface of the lock nut has an annular recess 28 from which a hole 29 extends downwardly as shown in Figure 6. Positioned in this recess is a helical spring 30 having on end bent downwardly and anchored in the opening 29. The other end of the spring projects upwardly and is anchored in an opening 3| in the bottom of the body member. A screw 32 is secured in a thread: ed opening in the body and serves as a stop for limiting the rotation of the lock nut in one direction. When the parts are in the position shown in Figures 3 and 6, the spring functions to hold the lock nut with the projection 21 engaging the stop 32 and to resist the frictional forces tendin to rotate the lock nut to locking position when the bolt is rotated in a clockwise direction looking upwardly in Figure 6. With a lock nut in this position therefore, the screw or bolt can be rotated freely in either direction. If the lock nut is turned towards the right a sufficient amount to bring its upper surface into engagement with the opposed lower surface of the body, it will clamp the bolt 20 in a manner common to all look nuts and'therefore by rotating the lock nut from the full line position shown in'Figure 3 to the dotted lineposition, the bolt 20 can be quite firmly clamped to the body and the latter can therefore be rotarily controlled by the bolt. When it. is desired to release the bolt 20 so as to permit it to rotate freely inthe body, it is first turned towards the left, whereupon the lock nut is permitted' to separate from the opposed surface of the body a suificient amount to reduce the friction whereupon the spring 28 functions and turns it until the projection 21 engages the stop 32 or tothe position shown in Figure 3. This releasing action is due, to some extent at least, to the backlash or slight lost motion between the threads of'the lock nut and those of the bolt. It is apparent from 'Figure 6 that spring 28 exerts a force tending to separate the nut from the body I 4 and'also after being given-an initial tension, produces a torque that tends to rotate the nut. Although a metal spring is believed to be the most desirableelement for the purpose indicated, it can be replaced by a rubber ring which becomes compressed when the nut is moved to locking position. Since thefrictional engagement of the upper and lower surface of such a rubber rin or spring, with the adjacent relatively movable surfaces produces a torque resisting forces when the lock nut is moved to locking position, it will function in substantially the same manner as the metal spring shown and therefore whenever the term spring is employed, it is intended to be construed broad enough to include any mechanical equivalent. 7

Since the clamp is designed for use in connection with transmission lines either while they are still charged or after they have been disconnected from the source of voltage, the clamp has been so designed that it can be secured to the upper'end of a long handle of insulating material such as that designated by reference numeral 33 in Figure 2. The handle has secured to its upper end a metal sleeve 34 withinwhich is slidably mounted a cup-shaped plunger 35. The wall of the plunger is provided with one or more elongated openings 36 into which the screws 3! project. A helical spring 38 is positioned in the plunger with its upper end abutting the bottom thereof and its lower end abutting the upper end of the handle 33. The upper end of the sleeve 34 is provided with two bayonet slots 39 for the reception of the pins 25. When the parts are in the position shown in Figure 3, the spring 38 is compressed sufficiently to hold the bayonet connection in operative position and therefore it will be seen that the bolt 20 forms an extension of the handle 33. When the lock nut is moved to operative position, the body [4 can be rotarily controlled by the operator and this facilitates the operation of efiecting a connection with the transmission line cable, which has been designated in Figure 3'by reference numeral 40.

For the purpose of securing the clamps to the ends of jumper cables the body M has, been provided with a laterally extending lug 4| having an opening for the reception of the jumper 42.

A set screw 43 serves to clamp the jumper cable in position. Each end of the jumper cable is provided with a clamp in the manner shown in Figure 1. V

Let us now assume that one or more of the jumpers shown in Figure 1 have been destroyed and are to be replaced. A jumper like that designated by as in Figures 1 and 2 is first, attached to the upper end of the handle by the means shown in Figure 3 after which the body is rotated until the head 22 is broughtdown below the lower surface of the'notch I5, the nut 26, is now rotated towards the right until it clamps the bolt 20 in the manner above explained. The

1ineman now raises the handle and hooks "the clamp over the cable in the manner shown in,

Figure 2. After the clamp is in place he rotates the handle towards the left, thereby releasing the lock nut and after this has occurred, he rotates the handle and bolt 20 towards the right until the parts assume the position shown in Figure 3, thereby clamping the cable firmly in place. The

handle can now be released by'moving it up- The Jumpers secured to the cables by the means v shown and claimed herein can be left in place as long as desired or they may be replaced by 'per manent fjumpers whenever it is convenient to disconnect both of the lines.

I want to call attention to the fact that with the clamping means shown in Figure 3 a large contact area between the clamp and the cable'is obtained. Whereas with flat parallel jaw clampers only line contacts are obtained and such clamps heat faster than the clamp shown herein due to the increased resistance.

From the above description it ,will be seen that theclamp that forms the subject of this invention is especially well adapted for use withhigh,

tension circuits and that on account of the lock nut the operator is in perfect control of the rotary position of the body member when applying ed clamping rod positioned in the opening in threaded engagement with the opening wall, means for turning the rod in the opening to move its end relative to the bottom of the hook, a lock nut positioned on and threadedly connected with the rod adjacent the end of the body, and a resilient member positioned between the lock nut and the body member and in contact with both, whereby it will be subjected to a distorting stress when the nut is turned toward locking position thereby producing a biasing force for returning the nut to unlocking position when the threaded rod is rotated in a direction to move its end away from the bottom of the hook.

2. A clamp comprising a body member having one end provided with a hook, the body having a threaded opening whose axis is in substantial alignment with the bottom of the hook, a threaded clamping rod positioned in the opening in threaded engagement with the opening wall, means for turning the rod in the opening to move its end relative to the bottom of the hook, a lock nut positioned on and threadedly connected with the rod adjacent the end of the body, and means comprising a spring for biasing the lock nut in a direction away from the end of the body whereby it will automatically move to inoperative position when the threaded rod is rotated in a direction to move its end away from the bottom of the hook.

3. A device in accordance with claim 2 in which the body and the lock nut are provided with cooperating stops for limiting their relative rotation in a, direction to move the lock nut away from the body.

JAMES DONOGHUE.

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