US3028146A

US3028146A - Fish tape

Info

Publication number: US3028146A
Application number: US845353A
Authority: US
Inventors: Sparks William
Original assignee: Individual
Current assignee: Individual
Priority date: 1959-10-09
Filing date: 1959-10-09
Publication date: 1962-04-03
Anticipated expiration: 1979-04-03

Description

A ril 3, 1962 w. SPARKS FISH TAPE Filed 001;. e, 1959 W/ ///0/77 p ar/w IN V EN TOR.

ATTORNEY) This invention relates to a tool for pulling cable or the like through a conduit. In one of its novel aspects, it relates to a fish tape which is so constructed to be flexible in different planes. In another of its novel aspects, it relates to a fish tape that is guided and supported in a conduit on spaced sleds or runners to provide for easy insertion and pulling of the tape through the conduit.

In the electrical industry and other industries, it is frequently necessary to pass cable or similar material through a conduit which may be laid in the walls, floors and ceilings of buildings or buried in the ground. The conduit may be of substantial length and may be bent or curved in different planes over its length. Usually it is not possible to push the cable itself through the conduit because of limited space, lack of rigidity in the cable or other reasons; therefore, it is common practice to pull the cable through the conduit by use of a pulling member, previously threaded through the conduit. Members used for this purpose are known in the electric wiring art as fish ta es.

One type of fish tape known in the art comprises a metallic shaft of substantially rectangular cross-section. While this rectangular fish tape is flexible about its major axis, it is virtually inflexible about its minor axis. Being flexible about a single axis, this fish tape is difficult to insert and pull through a conduit that may bend in more than one plane, particularly if the bends are relatively close together, since the tape must be twisted to expose its flexible axis to the new bending plane. In addition, a rectangular fish tape tends to ride along the conduit on its face or larger surface rather than its edge or smaller surface. This situation can cause a great amount of friction between the tape and conduit making it extremely difficult to insert and pull the tape through the conduit. The twisting action necessary to negotiate bends in different planes further increases the friction and resistance to movement of the tape through the conduit. 7

Another type of fish tape known to the art comprises a two-piece fish tape having an inner pulling element and an outer housing, for example, a steel spring, for guiding and supporting the inner pulling element. Neither of these elements contributes substantially to the function of the other, that is, the housing does not have sufficient stiffness or tensile strength to contribute signficantly to threading through the conduit or to the pulling function of the inner element, and the inner element does not contribute substantially to the guiding and supporting func-' tion of the housing during insertion of the tape through the conduit. This two-piece fish tape has other disadvantages and undesirable features. It is expensive to manufacture and diflicult to anchor the two elements together so that they will move as a unit through the conduit during the insertion operation and the pulling operation. Since the pull on this type of fish tape is exerted primarily on the inner element and the drag or friction is exerted primarily between the outer element and conduit, a high shearing force is created between the inner and outer elements during the pulling operation. This shearing force in some cases may shear the anchor connection between the inner pulling element and outer housing thereby separating the tape into two parts. In addition, the friction between the housing and conduit is relatively high since the housing is usually of substantially the same configuration in cross section as the conduit, and

atet ii as a result a large portion of the outer face of the housing drags on the conduit along its entire length. This friction between the housing and conduit makes it diificult to insert the fish tape through the conduit and substantially increases the pulling force required to pull the cable through the conduit.

An object of this invention is to provide a fish tape that will obviate the above difiiculties and disadvantages.

Another object of this invention is to provide a fish tape that is flexible in different planes.

Another object of this invention is to provide a fish tape having a low degree of friction during the insertion and pulling of the fish tape through a conduit.

Another object of this invention is to provide a fish tape for pulling cable or similar material through a conduit that is so constructed so as to be easily inserted and pulled through a conduit which may be of substantial length and which may have a number of bends in different planes along this length.

Another object of this invention is to provide a fish tape for pulling cable through a conduit, the fish tape being constructed of a plurality of elements, each element contributing in a substantial degree to the compressive strength or stiffness required to push the tape through the conduit and also contributing in a substantial degree to the tensile strength required to pull a tape and cable throughthe conduit.

Another object of this invention is to provide a fish tape of the type described in the above object which is so constructed that the individual elements alternatively form sleds or runners at spaced intervals along the length of the tape for guiding and supporting the fish tape with a Eninixnum of friction during its passage through the conuit.

These and other objects and advantages are realized by the practice of this invention in the forms illustrated in the drawings wherein at least two opposing pairs of elastically flexible elements are braided together to form a fish tape by crossing a first opposing pair of elements between a second opposing pair of elements and then crossing the second opposing pair of elements between the first opposing pair of elements before re-crossing the first opposing pair of elements. The ends of the elements at each end of the fish tape may then be secured, as by welding or crimping to a suitable eye or hook to provide a connection for attaching the fish tape to the cable on one end and to provide a coupling for a pulling device at the other end.

Such a fish tape has a series of spaced skids or runners approximately parallel to its longitudinal axis located at intervals around the face of the tape and along its length. These provide points of contact between the fish tape and conduit at spaced intervals along the conduit to guide and support the fish tape when it is passed through the conduit. Inasmuch as the fish tape contacts the conduit only at spaced intervals along its length, the friction or resistance to movement of the fish tape through the conduit is greatly reduced. This reduction in friction provides for easy insertion of the fish tape through the conduit and also provides for easy pull of the cable and tape through the conduit. This arrangement also reduces the tendency of the fish tape to spiral or twist as it is passed through the conduit.

It is intended that the term elastically flexible as used in the specification and claims be taken to include all elements known to the art as being suitably flexible and elastic for the construction of a fish tape according to this invention. For example, the elements may be of steel or plastic wire or filaments. In other applications, it may be desirable to use insulated wire to protect the operator from hot circuits in a fuse panel. In any event, the elastically flexible elements used in the constructicn of the fish tape of this invention should be sufficiently flexible to negotiate the bends which may be encountered in the conduit, yet have sufficient compressive strength and stifiness to feed through the conduit without buckling or doubling back when inserted therein by an operator. In addition, the elements should have sufficient tensile strength to pull a cable through the con dnit, even though a substantial force may be required to accomplish such a pull.

The elements making up the opposing pairs may comprise a plurality of strands, the strands comprising each element preferably being taken as a unit and braided with other elements as above described to provide the fish tape of this invention. The number of strands comprising each element can vary, depending upon the particular application involved. For example, for a given total tensile strength to be provided by the fish tape, greater flexibility for negotiating bends in a conduit is generally provided by utilizing a plurality of relatively small strands for each element rather than a fewer number of larger strands for each element. On the other hand, because of the pres ence of other cable in the conduit or other reasons, it may be desirable to provide a fish tape of relatively high compressive strength or stiffness to permit the fish tape to be inserted through the crowded conduit. In this case, a smaller number of relatively large strands in each element would be preferred. Other considerations can influence the number and size of strands to be used in a particular application.

In this connection, it will be understood that it is generally preferable that the elements of opposing pairs comprise an equal number of strands. Further, in some instances, it is desirable that the difierent opposing pairs comprising the fish tape of this invention include elements having an equal number of strands.

Referring now to the drawings wherein like characters are used to designate like parts:

FIG. 1 is a perspective view of one embodiment of the fish tape of this invention being passed through a conduit, the conduit being shown as bent in difierent planes and the conduit broken away to show the spaced points of contact between the tape and conduit;

FIGS. 2 and 3 are plan views of the fish tape of FIG. 1;

FIG. 4 is a section taken along the fish tape of FIG. 2 at the line 4-4;

FIG. 5 is a section of the fish tape of FIG. 2 taken along line 55;

FIG. 6 is a section of the fish tape of FIG. 2 taken along line 6-6;

FIG. 7 is a section of the fish tape of FIG. 2 taken along line 77; and

FIG. 8 is a section of another embodiment of this invention wherein each element of one opposing pair includes two elastically flexible strands.

In a preferred embodiment of this invention, the crossing of elements of opposing pairs, above referred to, is accomplished by sequentially twisting one opposing pair of elements in one direction intermediate the twisting of another opposing pair of elements in the opposite direction, each element comprising an equal number of elastically flexible strands.

Referring now to the drawings wherein the above embodiment is shown, and for reason of simplicity of illustration, each element is shown as comprising a single elastically flexible strand, for example, steel wire such as piano wire, the fish tape indicated generally at 15 comprises a braided body member 16 fashioned by braiding together opposing pairs of elements, one opposing pair being designated 17 and 17a, and the other opposing pair being designated 18 and 1811. As can be seen from FIGS. 2 through 7, the elements are braided together by twisting

opposing elements

17 and 17a in one direction intermediate the twisting of

opposing elements

18 and 18a in the other direction. This sequential twisting of one opposing pair of elements in one direction intermediate the twisting of the other opposing pair of elements in another direction is continued until a fish tape of the desired length is obtained. The ends of the elements at each end of the tape may then be secured, as by welding, to a coupling 19 to provide a means of connecting the fish tape at one end to the cable to be pulled through a conduit, and to provide a means at the outer end for pulling the fish tape and cable through the conduit.

Although the elements in this embodiment are braided together by twisting the opposing pairs of elements in opposite directions, it will be understood that it is with-in the scope of this invention to braid the elements together by crossing opposing pairs of elements intermediate the crossing of other opposing pairs of elements without twisting the elements of opposing pairs together.

One important feature of this invention is the provision of spaced skids or runners along the face of the braided body member for guiding and supporting the body member when it is passed through a conduit. This feature of the invention can be seen in FIG. 2 wherein the segmental portions of

elements

17 and 17a between their crossings 20 define such skids or runners alternatively along the length of body member 16.

Elements

18 and 18a define like skids or runners intermediate their crossings 22, the skids or runners formed by

elements

18 and 18a being disposed between the skids or runners of

elements

17 and 17a and in a plane at an angle thereto. These skids or runners defined by the elements intermediate their crossings provide points of con tact between the braided body member and the conduit at spaced intervals along the length of the conduit (FIG. 1) when the fish tape is passed through the conduit. Thus, as distinguished from fish tapes presently known in the art, the fish tape of this invention is guided and supported in the conduit by relatively widely spaced skids or runners along the length of the fish tape. This reduction in overall area of contact between the fish tape and conduit substantially reduces the friction or resistance to movement of the fish tape when it is passed through the conduit, thereby reducing the force required to insert the fish tape through the conduit and to subsequently pull the fish tape and attached cable through the conduit. In addition, it will be observed that the skids or runners defined by the elements lie in planes substantially parallel to the longitudinal axis of the braided body member, and

ence are directed toward, rather than across, the direction of movement of the fish tape when it is passed through a conduit. This arrangement further reduces the friction between the fish tape and conduit and also reduces the tendency of the fish tape to twist or spiral as it is moved through the conduit.

In the embodiment of FIG. 8, one opposing pair of elements, 23 and 24, comprise a plurality of strands, element 23 including strands 23a and 23b, and element 24 including

strands

24a and 24b. In this embodiment, opposing pairs of

elements

23 and and 24 are braided together with opposing pairs of

elements

25 and 25a, as above described, the strands making up each element being taken as a unit in the braiding operation.

The operation and use of the fish tape of this invention is as follows. A fish tape of desired length, constructed, for example, according to the foregoing embodiment, is threaded by pushing it through a conduit 21 (FIG. 1) and a cable is attached to the coupling at the end of the fish tape. The fish tape and cable are then pulled through the conduit by pulling on the coupling at the other end of the fish tape. Inasmuch as the braided body member of the fish tape of this invention is approximately equally flexible in all different planes, the fish tape may be inserted through the conduit without the necessary of twisting the fish tape to expose a flexible axis to bends in the conduit, even though such bends may be in dilferent planes and relatively close together. Further, each element comprising the fish tape of this invention not only forms skids for guiding and supporting the fish tape when it is passed through a conduit, but also contributes in a substantial degree to the required compressive strength or stiffness for inserting the fish tape through the conduit, and to the required tensile strength for pulling the fish tape and cable through the conduit.

From the foregoing it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth, together with other advantages which are obvious and which are inherent to the apparatus.

It will be understood that certain features and subcombinations are of utility and may be employed with out reference to other features and subcombinations. This iscontemplated by and is Within the scope of the claims.

As many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

The invention having been described, what is claimed is:

l. A fish tape for pulling cable or the like through a conduit, comprising, a plurality of opposing pairs of elastically flexible elements braided together, the braided elements being flexible in different planes and defining alternate skids spaced along the length of the tape to provide spaced points of contact between the fish tape and conduit for guiding and supporting the fish tape when it is passed through a conduit, said braided elastically flexible elements being contiguous along the length of said tape and having suflicient strength in compression to avoid buckling While being pushed through a conduit and sufficient strength in tension to pull a cable therethrough without substantial change in cross-sectional area of the tape and connecting means mounted on said elastically flexible elements for connecting said cable to said elements.

2. A fish tape for pulling a cable or the like through a conduit, comprising, a body member, said body member including at least two pairs of crossed opposing elements braided together, one pair of opposing elements being crossed intermediate the crossing of the other pair of opposing elements whereby the elements in each opposing pair of elements defined skids, each skid having a smooth continuous surface extending approximately longitudinally along the face of said body member intermediate the crossings of said opposing elements for contacting a conduit at spaced intervals along the conduit to guide and support the body member when it is inserted through the conduit, said elements being of an elastically flexible nature and having sufficient strength in compression to avoid buckling while being inserted through a conduit and suflicient strength in tension to pull a cable through the conduit, and connecting means mounted on said body member for connecting the body member to the cable to be pulled through the conduit.

3. A fish tape for pulling cable or the like through a conduit comprising, a body member bendable in ditferent planes, said body member including at least two opposing pairs of elastically flexible elements braided tothe body member to the cable to be pulled through the conduit.

4. A fish tape according to claim 3 wherein at least one of said elements comprises a plurality of elastically flexible strands.

5. A fish tape according to claim 3 wherein each element of at least one of said opposing pair of elements comprises a plurality of elastically flexible strands, each element of said opposing pair of elements having an equal number of said elastically flexible strands.

6. A fish tape according to claim 3 wherein each of said elements comprises at least one elastically fiexible strand, each of the elements having an equal number of said elastically flexible strands.

7. A fish tape for pulling cable or the like through a conduit, comprising, in combination, a braided body member, a coupling mounted on each end of the body member, said braided body member including elastically flexible means bendable in different planes for guiding and supporting the braided body member when it is passed through a conduit, said elastically flexible means having sufiicient strength in compression to avoid buckling while being inserted longitudinally through the conduit from one end thereof and sutficient strength in tension to pull a cable through the conduit, said elastically flexible means including at least two pairs of mutually twisted opposing elastically flexible Wires connected at the ends thereof to said couplings and being braided together intermediate said couplings, one pair of wires being twisted about each other in one direction intermediate the twisting of another pair of wires about each other in the other direction whereby the segmental portions of each pair of wires intermediate the crossings of such pair of wires define alternate skids along the face of the braided body member for contacting the conduit at spaced points along the conduit to provide said guiding and supporting of the braided body member when it is passed through the conduit, said skids having smooth longitudinally extending skid surfaces and being substantially parallel to the longitudinal axis of said braided body member.

References Cited in the file of this patent UNITED STATES PATENTS 832,343 Scott Oct. 2, 1906 1,020,672 Wilson Mar. 19, 1912 1,475,859 Nyman Nov. 27, 1923 2,142,641 Garris Ian. 3, 1939 2,750,152 Schinske June 12, 1956