Apparatus and Method of Threading a Closed Framed Opening by Helicopters

Referring now to the drawing in which a preferred embodiment of the invention is illustrated:

FIG. 1 is a diagrammatic view, partly in cross section, depicting successive manoeuvring movements of a helicopter in completing a threading operation utilizing an illustrative embodiment of this invention, the arrows A, B, C and D, indicating the successive directions of the helicopter in completing a threading operation;

FIG. 2 is a fragmentary top plan view of the trough device employed to uncouple the tow line coupling and recoupling the halves thereof to the respective ends of a cable loop;

FIG. 3 is a side elevational view of FIG. 2;

FIG. 4 is a fragmentary cross sectional view on an enlarged scale taken generally along line 4--4 on FIG. 2 but showing the hauling line coupling closely approaching the left hand end of FIG. 2 and about to be automatically uncoupled;

FIG. 5 is a cross sectional view taken along line 5--5 on FIG. 4;

FIG. 6 is a cross sectional view taken along line 6--6 on FIG. 4;

FIG. 7 is a fragmentary cross sectional view taken along line 7--7 on FIG. 4;

FIG. 8 is a fragmentary cross sectional view similar to FIG. 4 but showing the tow line coupling separated with the male half seated in the female coupling on the trailing end of the cable loop;

FIG. 9 is a cross sectional view taken along line 9--9 on FIG. 8;

FIG. 10 is a vertical cross sectional view taken through the right hand end of the threading apparatus shown in FIG. 1;

FIG. 11 is a cross sectional view taken along the broken line 11--11 on FIG. 10; and

FIG. 12 is a cross sectional view on an enlarged scale taken along line 12--12 on FIG. 3 and showing details of the clamping means securing the threading apparatus crosswise of the top of a power line tower.

Referring initially more particularly to FIGS. 1 to 3 and 12, the invention threading apparatus, designated generally 10, is shown clamped transversely of the cross frame 11 of a power line tower. The midlength of cross frame 11 typically supports the central conductor on the lower end of an insulator 12. A multi-sheave bundle stringing block 13 customarily employed in stringing bundle type power conductors is suspended by its frame 14 from the lower end of insulator 12 while the bundle conductor is being towed into position for connection to the insulator in lieu of stringing block 13. It will therefore be recognized that insulator 12 is suspended from the mid-section of the cross frame 11 interconnecting the inner and outer legs of the tower, not shown. Since the cross frame and the tower legs form a framed opening, a helicopter commonly employed for dropping a lightweight towing line for the main conductor hauling line cannot drop the tow line into the throat of a stringing block frame in accordance with the practise known to the prior art and shown, for example, in the U.S. Pat. No. 4,129,287 granted to Lindsey et al, Dec. 12, 1978. To circumvent this obstacle this invention utilizes a short length of flexible cabling, herein called a cable loop 15, having a female coupling attached to its trailing end and a rounded male coupling 17 attached to its leading end. These coupling halves are temporarily and releasably supported at the opposite ends of a trough 18 extending transversely of the tower cross frame 11. Trough 18 is rigidly clamped temporarily to the cross frame by clamps 19 which will be described in greater detail presently.

The remaining principal components of the threading apparatus comprise a separable tow line coupling 20 separably interconnecting the leading and trailing sections 21, 22 of the tow line. The leading end 21 is connected to helicopter 23 and the trailing end 22 leads to a supply reel not shown.

Before proceeding to describe structural details of the threading device it will be understood that the helicopter advances the hauling line from tower to tower. Initially it approaches a given tower in the highest position indicated in dot and dash lines in FIG. 1 until coupling 20 directly overlies the mid portion of trough 18. The helicopter then settles so as to deposit coupling 20 into the midlength of trough 18 and then moves a short distance to the left as indicated by arrow B allowing the tension in the hauling line to draw coupling 20 to the left hand end of the trough 18 where it is automatically uncoupled allowing its male component on the trailing end 22 of the line to become coupled to the female coupling 16 on the trailing end of cable loop 15. The helicopter then shifts forwardly, as indicated by arrow C, thereby trailing the female half of coupling 20 to the right and into coupling engagement with the right hand end of cable loop 15. The helicopter continues to move rightward as indicated by arrow D and, in so doing, carries the re-engaged coupling 20 forwardly toward the next tower with cable loop 15 now forming a section of the tow line.

Referring to FIG. 2, 3 and 12, it will be seen that the main body of apparatus 10 comprises an open ended trough 18 all except the opposite ends of which flare upwardly at an obtuse angle best illustrated in FIG. 12. Each end is generally cylindrical in shape slotted lengthwise of the top thereof by a slot 30 sized to freely pass the tow line and the tongue like arm 31 rigidly attached to the periphery of the forward end of the female half 32 of coupling 20. The right hand end of trough 18 is provided with an upwardly opening socket 33 (FIG. 2). The bottom of this socket has an elongated slot 34 (FIG. 2) to receive the leading end of cable loop 15.

Referring more particularly to FIGS. 3, 10 and 11, it will be noted that male coupling half 17 of the cable loop 15 is supported on the upper edges of a forwardly facing U-shaped positioning plate 36 protruding through and welded to the edges of slot 34. As clearly appears from FIGS. 10 and 11, the upper edge 37 of U-plate 36 is positioned to support coupling 17 with its center in axial alignment with the right hand cylindrical portion of trough 18. A tang 38 projects upwardly from the outer end of member 36 to safeguard against the coupling half becoming accidentally and prematurely dislodged from its seat. Additionally, a pair of spring biased ball detents 39 are pressed towards one another in aligned housings carried by the legs of U-shaped member 36 to hold cable loop 15 and coupling half 17 in proper position for coupling engagement with the cylindrical male half 32 of the tow line coupling 20. Cable loop 15 is manually pressed past balls 39 and cooperates with the bight portion at the inner end of the U-shaped member 36 in holding the cable loop and sphere 17 captive preparatory to coupling engagement with coupling member 32.

Before leaving FIG. 12, it will be noted that a channel shaped guide rail 40 with flaring sidewalls is welded to the bottom of trough 18. A pair of identical clamping assemblies 19 is slidable lengthwise of rail 40 and includes a pair of brackets 41 the upper ends 42 of which converge to loosely engage the sidewalls of rail 40. Ends 42 can be forced into snug clamping relation with rail 40 by tightening clamping bolts 43. Welded to the lower ends of brackets 41 is a V-shaped jaw 44 for receiving the horizontal flange of the tower cross frame 11.

Referring to FIGS. 2-6, it will be observed that the outwardly flaring sidewalls of trough 18 converge and merge with a cylindrical section 49. The uppermost portion of these converging and cylindrical walls have a slot 30 accommodating both the tow line and tongue 31 of the female coupling 32 of the tow line. Accordingly, slot 30 permits tongue 31 to advance rearwardly until the two halves of coupling 20 are disengaged by means to be described presently.

Cupped over and welded to the rear end of member 49 is an end cap 50 having two important principal functions, namely, uncoupling the halves of coupling 20 and releasably supporting the female coupling half 16 on the trailing end of cable loop 15. End cap 50 has a deep vertical slot 51 through which the trailing section 22 of the hauling line drops when the helicopter manoeuvres coupling 20 between the positions associated with arrows A, B and C in FIG. 1. Extending upwardly and outwardly from the opposite sides of the aligned slots 30 and 51 are V-shaped guide horns 53, 53 (FIGS. 2 and 3) supported by brace rods 54. These guide horns supplement the flaring sidewalls of trough 18 in guiding tow line 22 into trough 18 and assuring that the line enters slots 30 and 51 at the rear end thereof.

The female coupling 16 of the cable loop, best shown in FIGS. 4, 5, 8 and 9, has an elongated main body provided with an egg shaped socket 55 opening through one lateral edge of its mid-length, as clearly appears from FIG. 8. One end of coupling 16 is secured to the trailing end of cable loop 15 and its opposite end is slotted at 56 from end to end of socket 55 thereby to freely pass the trailing end 22 of the tow line. The male coupling half 57 fixed to the forward end of hauling line 22 is admitted into socket 55 upon release from coupling 20 and is locked coupled thereto by a locking pawl 58 (FIG. 8). Pawl 58 is pivotally supported on a pin 59 extending crosswise of a passage 60 in the body of coupling member 16. A torsion spring 61 encircles pin 59 and urges pawl 58 clockwise against a stop but permits the pawl to pivot counter-clockwise to admit sphere 57 into socket 55.

The outer end of cap 50 is provided with a generally rectangular pocket 60 loosely seating coupling 16 with the inlet of its socket 55 aligned with the axis of trough 18. As is best shown in FIGS. 5 and 9, coupling 16 is held releasably seated in socket 60 by spring biased ball detents seating in depressions 64 formed in the outer faces of coupling 16.

The hauling line coupling 20 and its release mechanism will now be described by reference to FIGS. 4, 5, 8 and 9. This coupling comprises a cylindrical main body or female half 32 and a sperical male half 57. Half 32 is tubular and formed from end-to-end with a keyhole passage including a bulbous central passage 68 sized to freely pass sphere 57 and with a slot 69 sized to freely pass cable loop 15. Slot 69 is diametrically opposite the hauling tongue 31 of coupling half 32 and permits the forward end of the cable loop to enter the forward end of slot 69 and to exit from its rear end.

The means releasably retaining halves 32 and 57 coupled together comprises a pair of ball detents 70 held captively assembled in aligned radial passages 71 in the main body of coupling half 32 (FIG. 5). Normally detent balls 70 are held locked in their inwardly extended position shown in FIG. 5 by a pair of locking pins 72 reciprocably supported lengthwise of half 32 and spring biased outwardly by a spring 73. Assembly screws 74 project into elongated notches 75 in pins 72 and limit their reciprocal movement. Each pin is provided with a semi-spherical socket 77 positioned to receive detents 70 when the pins are shifted to the right as viewed in FIG. 5. A split bumper ring is fixed to the outer ends of pins 72 and are located in a shallow axial well 79 at the trailing end of coupling half 32. This well provides adequate room for the operation of pins 72 and bumper ring 78 and safeguards against the accidental and unintended movement of the bumper.

The means for depressing bumper 78 and releasing female coupling member 57 from coupling half 32 comprises a tubular member 81 forming an integral part of end cap 50 and in axial alignment with the central passage 68 of coupling 20 and the inlet of socket 55 of coupling member 16 attached to the cable loop. The forwardly projecting larger diameter end of tubular member 81 is positioned to engage bumper 78 as the coupling moves rearwardly and to cooperate therewith in guiding the coupling sphere 57 through tube 81 and into the socket of coupling 16.

The operation of the automatic framed-opening threading device 10 will be readily apparent from the foregoing description of its components. Each stringing block or window frame to be threaded is equipped exteriorly and crosswise thereof with one of the threading devices 10 such as to the cross bar 11 of a power line tower. A cable loop 15 is installed at the opposite ends of the trough 18 with its male coupling member 17 installed at the leading end of the trough and its female coupling 16 gripped in pocket 60 at the trailing end of the trough as shown in FIG. 1. An aerial transport, such as helicopter 23, having tow line sections 21, 22 connected by the separable coupling 20 in clear viewing range of the pilot is then advanced toward the framed opening to be threaded. When the helicopter has approached to the uppermost position shown in FIG. 1 with coupling 20 directly overlying the mid-portion of the trough, the pilot lowers the aircraft to deposit coupling 20 into the mid-portion of the trough. Guide horns 53, 53, channel line 22 into slots 30 and 51. At this point, the pilot manoeuvres the aircraft slowly rearward as indicated by arrow B allowing the tension in the tow line to carry coupling 20 rearwardly in the trough, coupling 20 being guided by the converging rear end of the trough into tubular member 49. As the coupling approaches the tubular stop 81, bumper 78 engages the stop thereby depressing pins 72 thereby permitting the male coupling half 57 of the tow line to expand the detent balls 70 outwardly into recesses 77 (FIG. 9). Coupling half 57 then passes rearwardly through the tubular stop 81 into the pocket 55 of the cable loop coupling 16. As the coupling 57 enters the pocket it rocks pawl 58 (FIG. 8) counterclockwise whereupon string 61 immediately returns the pawl to its normal extended position to safeguard against separation of coupling halves 16 and 57. The weight and tension acting in the trailing end 22 of the tow line promptly releases coupling 16 from its retaining ball detents 63 (FIG. 5) and tensions the cable loop 15 the leading end of which continues to be held firmly captive in the leading end of trough 18.

The pilot then reverses the helicopter as indicated by arrows C, C and shifts the craft horizontally forward thereby shifting female half 32 of the coupling forwardly. The converging sidewalls of trough 18 (FIG. 2) engage tongue 31 of coupling half 32 and guide it into slot 30 in an upright position thereby assuring that the keyhole passage 68, 69 is properly oriented to receive cable loop 15 and its male coupling half 17. Coupling 17 is held captive near the rear end of keyhole passage 68, 69 by detent balls 70 which are locked against retraction by pins 72 and springs 73 (FIG. 5). Cable loop 15 is now fully inserted and locked assembled between tow line sections 21 and 22. This having been accomplished the pilot manoeuvres craft 23 forwardly in the direction indicated by arrow D thereby lifting coupling 20 upwardly out of the forward end of trough 18 and releasing the cable loop 15 from the ball detents 39, 39 (FIGS. 10, 11).

The pilot now moves forwardly to the next closed frame or window equipped with one of the threading devices 10 thereby advancing the tow line through the throat of the first stringing block 13. The manoeuvring operations described above are then repeated to insert the cable loop preassembled to the next threading device whereupon the second cable loop is inserted between the female half 32 of coupling 20 and the leading end of the previous cable loop.

While the particular apparatus and method of threading a closed framed opening by helicopters herein shown and disclosed in detail is fully capable of attaining the objects and providing the advantages hereinbefore stated, it is to be understood that it is merely illustrative of the presently preferred embodiment of the invention and that no limitations are intended to the detail of construction or design herein shown other than as defined in the appended claims.