Portable Device for Storing an Endless Metallic or Fiber-Optic Cable

1. Field of the Invention

This invention pertains to cable handling, and more particularly to apparatus for laying underground cable.

2. Description of the Prior Art

The contribution of fiber-optics to the communications age is well known. With fiber-optics, thousands of messages can be transmitted simultaneously through a single fiber.

A major problem associated with fiber-optic technology concerns the placement and protection of the fiber-optic cables. It is generally accepted practice to lay fiber-optic cables underground below the frost line. Various equipment has been developed to efficiently lay the cable across fields and other unobstructed areas. However, substantial difficulties are encountered when the fiber-optic cable must be laid under such obstructions as highways, railroads, and gas and oil pipelines. Splicing fiber-optic cables is both costly and detrimental to the strength and quality of the light signals to be pulsed through the cables.

To lay splice-free cables under various obstructions, it is known to unwind an entire supply reel of cable at the obstruction. The cable is pulled back and strung in one or more long loops stretching away from the obstruction. The cable free end is then fed through a bore under the obstruction. Finally, the cable is rewound on the supply reel located on the downstream side of the obstruction. A variation of the pull-back method is the FIG. 8 method. The cable is entirely unwound from the supply reel, but it is laid in the form of several overlapping figure-8s on the ground. Both the pull-back and figure-8 methods are very time consuming and therefore costly ways of passing cables under obstructions. Further, laying the fiber-optic cables on the ground renders them susceptible to damage by machinery and personnel in the area.

Manitou Industries of Neilburg, Saskatchewan, Canada has developed apparatus that eliminates the need for laying the cable on the ground at an obstruction. The Manitou device employs a pair of special cable reels that give access to the cable free end underlying the overlying cable of the supply reel. At an obstruction, the plow supply reel is unloaded from the plow and placed on the ground. The cable free end is pulled from the special reel and is partially unwound by an unwinding tower attached to the reel. The cable free end is passed under the obstruction. The cable free end is then wound onto a second special reel on a trailer located on the downstream side of the obstruction simultaneously with unwinding the cable from the original supply reel attached to the unwinding tower. The second reel is then unloaded from the trailer and loaded onto the plow, where it becomes the plow supply reel for supplying cable until the next obstruction is reached. At the next obstruction, the reel unloading, unwinding, rewinding, and reloading process is repeated. Although the Manitou system is an improvement over merely laying the cable on the ground, it nevertheless requires substantial time to unload and load two reels at the obstructions. Further, a substantial expenditure is required for the special reels and the machinery for handling them.

Thus, a need exists for improved apparatus and methods for laying continuous underground cables.

In accordance with the present invention, portable storage equipment is provided that efficiently handles endless metallic or fiber-optic underground cable at various obstructions in the cable path. This is accomplished by apparatus that includes a rotatable drum and bail that temporarily wind the cable onto an adjacent storage reel without requiring access to either end of the cable.

The drum and bail are mounted on a relatively small trailer that is towable by a motor vehicle, such as a pick-up truck. The drum is mounted for rotation about its longitudinal axis on the trailer. The storage reel is fixedly mounted on the trailer adjacent the drum, with the drum and reel longitudinal axes being coincident. In addition to rotating, the drum reciprocates along its longitudinal axis. The bail extends axially from the end of the drum so as to overhang the fixed reel for all axial locations of the drum relative to the reel.

The drum is formed with a radial slot extending the full length thereof. In addition, the mounting frame and bearings that rotatably support the drum on the trailer have radial slots alignable with the drum slot. A portion of the stationary reel also has a longitudinally extending radial slot, but the entire length of the reel need not be slotted. The reel slot is in angular alignment with the frame slots. A long inner tube loosely mounted inside the drum mounting frame also has a longitudinal slot for the majority of its length.

A pair of rollers mounted to the trailer contact and help support the drum periphery. A hydraulic circuit operates a pair of motors that drive the rollers for rotating the drum. A third hydraulic motor rotates a lead screw that cooperates with a drum gripping mechanism to reciprocate the drum along its longitudinal axis in timed relation to the drum rotation.

Also attached to and extending axially from the drum are a series of different length strips. A spring loaded snatch block is fixed to the free end of each strip. Openings in the snatch blocks cooperate to guide the cable in a smooth three dimensional path to the bail. To guide the cable running end to the first snatch block, the portable storage equipment of the present invention includes a double ended guide funnel. The funnel is split longitudinally into two halves, and each half is pivotally mounted to the trailer. When the funnel halves are properly located and latched together, they mate to capture the cable and create a smooth cable guide.

In operation, a cable laying tractor or plow with a supply reel of cable lays the cable underground in a normal fashion until it reaches an obstruction, such as a highway. At that point, the portable apparatus of the present invention is brought up and parked near the plow. The drum is rotated until the radial slot therein is aligned with the slots in the support frame and in the stationary reel. Some slack is produced in the cable by the plow. The cable slack is inserted transversely through the aligned slots in the support frame, drum bearings, drum, inner tube, and reel. A large loop of cable is formed inside the stationary reel and is retained in place within a longitudinally slit piece of tubing. The plow end of the cable, which remains passing through the reel slot, is wound a few turns around the reel, and then it is passed transversely through the bail, snatch blocks, and guide funnel. The hydraulic circuit of the invention is actuated to rotate and reciprocate the drum together with the bail and snatch blocks, thereby unwinding the cable from the plow supply reel and winding it onto the stationary reel.

After the cable is completely unwound from the plow supply reel and wound onto the portable storage reel of the present invention, the plow is free to cross the obstruction in any convenient and safe manner. The cable free end is fed through a bore under the obstruction and then reattached to the supply reel on the plow. A reverse procedure is then performed with the drum and bail rotating and reciprocating to unwind the cable from the temporary storage reel at the same time the cable is being rewound onto the plow supply reel. The plow then resumes laying the cable in the normal fashion, and the trailer is towed to the next obstruction in the cable path.

Other objects, aims, and advantages of the invention will become apparent to those skilled in the art upon reading the disclosure.

FIG. 1 is a side view showing the portable storage apparatus of the present invention in operation with a cable laying plow.

FIG. 2 is an enlarged top view of the portable storage apparatus of the present invention.

FIG. 3 is a cross-sectional view taken along lines 3--3 of FIG. 2.

FIG. 4 is an enlarged partially broken side view of the portable storage apparatus of the present invention.

FIG. 5 is a cross-sectional view taken along lines 5--5 of FIG. 4.

FIG. 6 is a view taken along lines 6--6 of FIG. 4.

FIG. 7 is a view taken along lines 7--7 of FIG. 4.

FIG. 8 is an enlarged cross-sectional view taken along lines 8--8 of FIG. 4.

FIG. 9 is a side view of the inner tube of the portable storage apparatus of the present invention.

FIG. 10 is a cross-sectional view taken along lines 10--10 of FIG. 9.

FIG. 11 is a cross-sectional view taken along lines 11--11 of FIG. 9.

FIG. 12 is an enlarged front view of a snatch block used on the portable storage apparatus of the present invention.

FIG. 13 is a cross-sectional view taken along lines 13--13 of FIG. 12.

FIG. 14 is a side view of the portable storage apparatus and plow in the position for rewinding the cable onto the plow supply reel.

FIG. 15 is a schematic diagram of the hydraulic circuit of the present invention.

Although the disclosure hereof is detailed and exact to enable those skilled in the art to practice the invention, the physical embodiments herein disclosed merely exemplify the invention which may be embodied in other specific structure. The scope of the invention is defined in the claims appended hereto.

Referring to FIG. 1, a portable storage apparatus 1 is illustrated that includes the present invention. The storage apparatus is particularly useful for cooperating with a conventional plow 3 for laying underground flexible cable 5, but it will be understood that the invention is not limited to cable laying applications.

In the normal operation, the plow 3 comprises a tractor 7 designed for off-road use over ground surface 9. The tractor supports a supply reel 11 that holds as much as 19,000 feet of fiber-optic or other endless cable 5. The tractor is further equipped with a conventional earth trenching device, schematically represented at 13, as is known in the art. The trencher 13 opens a trench 15 in the earth and may also be designed to fill the trench. The tractor 7 includes suitable means 17 for guiding the cable in long smooth arcs from the reel 11 into the trench 15.

In accordance with the present invention, the portable storage apparatus 1 is used to assist the cable laying plow 3 to lay the cable 5 under horizontal obstructions in the path of the cable route. Typical obstructions encountered in cable laying operations include railroad tracks, highways, and natural gas and oil pipelines. In FIG. 1, an obstruction in the form of a road 19 is illustrated.

The cable storage apparatus 1 comprises a trailer 21 having a flat horizontal frame 23 supported on conventional wheels and axles 25. The trailer 21 includes a tongue 27 equipped with a hitch 29 for towing the apparatus by a conventional vehicle, such as a pick-up truck, not shown.

Mounted to the trailer frame 23 is a large cylindrical drum 31. The drum 31 is mounted for rotation about its longitudinal axis 33 by mechanisms to be described presently. Referring also to FIGS. 3-7, a radial slot 38 is formed in the drum. The slot 38 extends for the entire length of the drum.

The drum 31 is partially supported by rollers 37 that are rotatably mounted on the trailer frame 23 by suitable brackets 39. The rollers 37 may be rubber tires. To rotate the rollers, orbital hydraulic motors 40 are fastened to the brackets 39, and the motor shafts are coupled to the respective rollers.

The drum 31 is further supported by a long center tube 41 that extends through the center of the drum concentric with the drum axis 3 and that projects out both drum ends. The center tube 41 is manufactured with a long slot 42 that extends from the tube front end 43 to a location beyond the drum back end 44. The tube front end 43 is mounted in a stationary manner by a support 45 firmly fixed to the trailer frame 23. In the illustrated construction, the support 45 comprises two pairs of braces 49 joined at their upper ends to housings 46. The center tube passes through and is welded to the housings 46. For additional rigidity, a pair of plates 51 are welded to the braces 49, and another plate 52 is welded to the housings 46. The drum rotates about axis 33 on the tube 41 by means of bearings 47, as is best shown in FIG. 3. The bearings 47 have radial slots aligned with the drum slot 38. The housings 46 are formed with radial slots 48, FIG. 6, that are aligned with the slot 42 in the center tube 41.

In addition to rotating about its longitudinal axis 33, the drum 31 also reciprocates therealong. For that purpose, the drum front end includes a flange 53 that is captured by a gripping mechanism 54. Looking also at FIGS. 2 and 8, the gripping mechanism 54 comprises two pairs of flat rollers 55. The flange 53 is gripped between the pairs of rollers 55, which are mounted on short shafts to the top side of a plate 57. To the underside of the plate 57 are mounted two pairs of grooved rollers 59. The flat rollers 55 and plate 57 are located on a longitudinally extending guide plate 61 having tapered edges received by the grooves in the rollers 59. The ends of the guide plate 61 are supported on the trailer frame 23 by suitable brackets 63. To reciprocate the drum, a lead screw 65 mates with a nut 67 fixed to a horseshoe 69. The ends of the horseshoe 69 straddle the guide plate 61 and are bolted to the plate 57. To rotate the screw 65 and thus translate the drum, the screw is connected by suitable drive means 71 to a hydraulic motor 73. The drum reciprocates between the position shown in the solid lines of the drawings and a position wherein the drum front flange 53 is in the general location shown by the phantom lines 53'.

Mounted to the back end 75 of the center tube 41 is a stationary hollow reel 77. The reel 77 may be held in place on the center tube by a handled nut 79 threaded onto the center tube end 75. To permit different sized reels to be mounted on the center tube, a spacer 81 may be interposed between the nut 79 and the reel. The reel is formed with a radial slot 78 that extends through the reel core 80 and the front flange 82. A slotted tube 84 is fixed circumferentially around the inner diameter of the reel core 80 at the back end thereof. The slotted tube 84 extends approximately three-fourths of the way around the inner diameter of the reel core as is best shown in FIG. 7.

Extending through generally the entire length of the center tube 41 is an inner tube 83. The inner tube 83 is loosely contained within the center tube, such that it may be freely turned within the center tube. The inner tube is preferably made from a synthetic plastic material, such as polyvinylchloride. Turning to FIGS. 9-11, the inner tube is fabricated with a slot 85 that starts at the front end 86 and extends almost the entire length of the inner tube and that passes completely through the tube wall. The slot 85 is generally parallel to the longitudinal axis for the major portion of the inner tube length. However, near the back end 87 of the inner tube, the slot 85 deviates in an angular manner for a short distance at locations 89. A short offset section of longitudinal slot 85' joins the two angular sections 89, thereby forming a lip 88 of material. The slot 85 terminates at a location 96 that is between the flanges of the reel 77 when the inner tube is inserted into the center tube. Preferably, the slot end location 96 is close to the reel front flange 82. To facilitate locating and turning the inner tube within the center tube, the inner tube front end is formed with a flared portion 91.

Attached to the periphery of the drum 31 is an arm 35 that extends longitudinally over the back end 44 of the drum, as best seen in FIGS. 2 and 7. To the free end of the arm 35 is fastened a hook-like bail 36.

Also extending longitudinally from the back end 44 of the drum 31 are a series of stiff strips. Five strips 93a-93e are illustrated in FIGS. 1, 2, 4, and 7, but it will be appreciated that more or fewer strips may be employed. The strips 93 are spaced circumferentially around a portion of the drum periphery. The strips are of unequal length, with one end strip 93a being the longest, and the opposite end strip 93e being the shortest. The shortest strip 93e terminates forward of the back flange 95 of the reel 77 when the drum is in the backmost position, i.e., when the drum is in the position in the solid lines of the drawings. To increase the rigidity of the strips, their free ends may be connected together with cross strips, such as strip 92 between strips 93b and 93c in FIG. 2. For clarity, the other stiffening strips are not shown in the drawings.

Attached to the free end of each strip 93a-93e by any suitable means, such as a plate 94, is a respective snatch block 97a-97e. With particular attention to FIGS. 12 and 13, the snatch blocks 97 may be composed of two symmetrical halves 99 pivotally joined by a spring loaded hinge 101 that is biased to the closed position of the drawings. The openings 103 through the halves 99 are smoothly radiused, as at 105, at their junctions with the half faces. Preferably, the snatch blocks are made of a non-metallic material.

Turning back to FIGS. 1-7, the plates 94 are welded to the strips 93 at appropriate angles thereto, such that the snatch block openings 103 define a smooth continuous path in three dimensions. The path begins at snatch block 97a. The axis of opening 103 of the end snatch block 97a is approximately parallel to the drum axis 33. The path ends at snatch block 97e. The axis of the opening of the snatch block 97e is approximately perpendicular to the drum axis and is generally aligned with the opening in the hooked bail 36. The openings of the intermediate snatch blocks 97b-97d are arranged to provide a smooth transition between the two end snatch block openings.

In FIGS. 1 and 2, reference numerals 107 represents posts upstandingly fixed to the trailer frame 23. Additional similar posts are fixed to the frame along the two sides thereof, but for clarity they are not shown. The posts 107 are used to hold expanded metal or similar guarding material. Pivotally connected to the posts at the back end of the trailer 21 are a pair of gates 109. The pivotal connection may be by conventional hinges 111. The gates 109 have frames made of square tubing or angle iron. Expanded metal guarding spans the opening areas between the gate frames. Pivotally connected, as by hinges 113, to the free ends of the gates 109 are respective second gates 115. During transportation of the portable storage apparatus, the gates 109 and 115 are folded to a closed inoperative configuration against the back end of the trailer, as shown by the phantom lines 109' and 115'.

Mounted to the free end of each gate 115 is one half 117 of a double flared guide funnel 119. The funnel halves 117 have flared inner diameters 121. Mounting of the guide halves to the gates may be by plates 123. As best seen in FIG. 2, the two guide halves are matable to form the enclosed guide 119 when the gates 109 and 115 are in the unfolded operative configuration. A conventional latch is employed to retain the free ends of the gates 115 together and thereby hold the two guide funnel halves in place.

In the preferred embodiment, the portable storage apparatus 1 of the present invention includes a hydraulic system for rotating and reciprocating the drum 31. The hydraulic system is powered by a conventional internal combustion engine located under the support 45 and schematically represented as reference numeral 123 in FIG. 6. The engine 123 drives a conventional hydraulic pump, which forms part of a hydraulic power unit 125, as is known in the art. Suitable hydraulic lines lead from the hydraulic power unit 125 to the hydraulic motors 40 and 73.

FIG. 15 shows a schematic diagram of the hydraulic circuitry associated with the portable storage apparatus 1 of the present invention. The circuitry includes a hydraulic pump 127 driven by the internal combustion engine 123 and supplied with hydraulic fluid from a reservoir 129. Hydraulic fluid under pressure is pumped to hydraulic motor 73 for reciprocating the drum 31 and to hydraulic motors 40 for rotating the drum. Directional control valves 131 and 133 are used to reverse the direction of rotation and reciprocation, respectively. Valves 135 and 137 assure proper synchronization between drum rotation and reciprocation.

Returning to FIG. 1, the plow 3 moves from left to right. It will be assumed that the plow has laid a length of fiber-optic or other flexible cable 5 from the supply reel 11 in the trench 15. For the normal cable laying operation, the trencher 13 is in an operative position such that it engages the earth to dig the trench, and the cable is laid on the trench bottom 139. It will further be assumed that an obstacle in the form of a road or highway 19 lies in the path of the cable. In accordance with the present invention, the plow 3 retracts the trencher 13 to an inoperative position, such as is shown in FIG. 1, when the plow is approximately 50 feet from the road. The plow continues to advance to the edge of the road, laying the cable 5 on the surface 9 of the ground. A few feet of slack are unwound from the supply reel.

The portable storage apparatus 1 of the present invention is then towed to a location near the plow 3. Preferably, the storage apparatus is parked between the plow and the end of the trench 15, with the drum axis 33 approximately parallel to the slack cable on the ground. The drum 31 is rotated under hydraulic power by the rollers 37 and motors 40 until the drum slot 38 is in angular alignment with the slots 48 in the housings 46 and with the slot 42 in the center tube 41. The inner tube 83 is manually positioned such that the slot 85 therein is aligned with the center tube and drum slots. Referring also to FIGS. 2-7 and 10, the slack cable 5 laying on the ground is then picked up, starting at the trailer front end. The cable is fed transversely through the slots 48 in the housings 46, through the slot 42 in the front end 43 of the center tube 41, and through the slot 85 in the inner tube, such that the cable is supported inside the inner tube. The cable, which has attained a position 5' at the front end of the trailer 21, is further fed through the slot 38 in the drum 31, and through the center tube and inner tube slots in line with the drum slot, such that the cable is supported in the inner tube from the front end 86 thereof to the drum back end 44. The cable 5' is inserted through the slot 78 in the reel front flange 82 and the core 80. The cable is further pushed through the center tube slot 42 and inner tube slot 85 underlying the reel core 80. The inner tube is rotated manually by means of the flared end 91 to enable the cable to be inserted through the angular slots 89, and the short offset slot 85' up to the slot end 96. The lip 88 on the wall of the inner tube overlaps the center tube slot 42 and thereby prevents the cable inside the inner tube from escaping through the slots 85 and 42. With the cable inside the inner tube as far as the slot end 96, additional cable is pushed through the reel slot 78 to create a large loop 140 inside the reel inner diameter 90. The cable loop 140 is guided into the upper end 141 of the tube 84 fixed to the reel inner diameter. The cable loop passes beyond the retainer tube lower end 143. Because there is no slot in the reel back flange 95' the cable remains positioned permanently through the slot 78 near the back flange 95. The cable may be wrapped around the reel core 80 and inserted transversely into the bail 36. From the bail, the cable is inserted transversely into the snatch blocks 97, which are successively opened to receive the cable and then closed by means of the spring loaded hinges 101. Finally, the cable is positioned within one of the guide funnel halves 117. The gates 109 and 115 are positioned to bring the funnel halves together to form the guide funnel 119, with the cable captured therein. The gates are latched in place.

The internal combustion engine 123 of the portable storage apparatus 1 is then started to operate the hydraulic power unit 125. In a first position, the control valve 131 will cause the drum 31 to turn in the direction of arrow 147 of FIG. 7, thereby winding the cable 5' onto the reel 77 and unwinding the cable from the plow supply reel 11. Simultaneously, control valve 133 causes the drum to reciprocate along axis 33 to create neat layers of cable on the reel 77. The smooth continuous path formed by the guide funnel 119, snatch blocks 97, and bail 36 permit winding the cable without damage. In that manner, the cable is windable onto the storage apparatus of the present invention without having access to either cable end.

Eventually, the entire cable 5 is unwound from the plow supply reel 11 and wound onto the storage reel 77. When that has occurred, the plow 3 is driven across the road 19 at any safe and convenient location. Meanwhile, the trench 15 is completed up to the road by other known equipment.

Turning now to FIG. 14, the plow 3 is shown in a new location across the road 19. A tunnel 149 is bored under the road. The cable free end is threaded through the bore 149 and reattached to the plow supply reel 11. The storage apparatus hydraulic circuitry is operated to rotate the drum in the direction of arrow 151 in FIG. 7, thereby unwinding the cable from the reel 77. At the same time, a suitable drive on the plow operates to wind the cable back onto the supply reel. When all the cable is unwound from the storage reel 77, the cable is pulled transversely out of the various slots 42, 38, 48, 85, 85', 89, and 78; bail 36; snatch blocks 97; retainer tube 84; and guide funnel 119. The cable is laid within the trench 15 up to the road and then wound by the plow supply reel to take up the slack. The plow is then able to resume cable laying operations in a normal manner. The trailer 21 is towed to the next road or other obstruction in the cable path.

Thus, it is apparent that there has been provided, in accordance with the invention, a portable device for storing an endless metallic or fiber-optic cable that fully satisfies the aims and advantage set forth above. While the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications, and variations as fall within the spirit and broad scope of the appended claims.