US3156449A - Method of threading cable through conduit - Google Patents

Description

Nov. 10, 1964 G. c. ENSLEY 3,156,449

METHOD OF THREADING CABLE THROUGH CONDUIT Filed Dec. 31, 1962 INVENTOR. Glover C. Ens/ey mum ATTORNEYS United States Patent 3,156,449 METHOD OF THREADING CABLE THROUGH CONDUIT Glover C. Ensley, 525 N. Woodland Drive, North Kansas City, Mo. Filed Dec. 31, 1962, Ser. No. 248,800 2 Claims. (Cl. 254-1343) This invention relates to a device and method for pulling electrical conductors and the like through protective conduits or tubes during electrical construction jobs.

The principal objects of the present invention are: to provide a device and method whereby pulling force may be easily increased over conventional devices and methods for drawing electrical cable through conduits; to provide such a device and method for threading electrical cables through conduits wherein one man may exert a pull heretofore obtainable only by using at least two men or with auxiliary power driven apparatus; to provide such a device and method which takes advantage of a sheave or pulley to double the pulling force exerted on the electrical cable in the conduit; to provide such a sheave which is adapted to slide longitudinally through the conduit without catching or jamming therein and which is easily disassembled for threading the pull rope therethrough intermediate the ends of the pull rope; and to provide such a device and method which is simple and inexpensive to use and produces substantial cost savings in both new construction and the alteration of existing construction.

Other objects and advantages of this invention will become apparent from the following description taken in connection with the accompanying drawings wherein are set forth by way of illustration and example certain embodiments of this invention.

FIG. 1 is a perspective view of a conduit sheave embodying this invention.

FIG. 2 is an exploded perspective view showing the sheave of FIG. 1 disassembled for receiving the loop of a pull rope.

FIG. 3 is a cross-sectional view taken on the line 33 of FIG. 1 showing the cooperating structure for maintaining the sheave parts in assembled relation but easily disassembled.

FIG. 4 is a fragmentary cross-sectional schematic View of an electrical conduit illustrating a conventional electricians snake being used for threading a doubled pull rope therethrough.

FIG. 5 is a fragmentary cross-sectional schematic View of the conduit illustrating the sheave cooperating with the pull rope for threading or pulling electrical cable therethrough with a 2-to-1 mechanical advantage.

Referring to the drawings, in more detail:

The reference numeral 1 generally indicates a conduit sheave embodying this invention. The sheave 1 has a body 2 with the rear end 3 thereof formed into an inwardly tapering conical section 4 and having an anchor eyelet 5 secured longitudinally thereto. The body 2, in the illustrated example, is generally cylindrical in shape and is divided or bifurcated into a pair of laterally spaced parallel legs 6 and 7. The spacing between the legs 6 and 7 forms a notch or opening 8 into which is received a pulley roller 9. The legs 6 and 7 terminate at the outer ends 10 thereof in rounded corners and curved configuration, the purpose which will be explained hereinafter, defining the forward end 11 of the body 2.

The pulley roller 9 is rotatably mounted between the legs 6 and 7 by means of a pin axle 12 having a square head 13 at one end thereof adapted to be received in a square recess 14 extending into the leg 7 to prevent pin rotation. Aligned bores 15 and 16 extend through the respective legs 6 and 7 for receiving the pin axle 12. The other end of the pin axle 12 has an annular recess 17 extending therearound supporting a split ring 18 which normally has an outside diameter slightly greater than the diameter of the bores 15 and 16. The ring 18, however, is resilient and radial compression thereon urges the ring to an outside dimension equal to the bores 15 and 16 whereby the pin axle 12 may be inserted through the bores 15 and 16 with hand pressure.

The leg 6 includes a counterbore or recess 19 extending thereinto and forming a shoulder 20 past which the ring 18 may expand to the uncompressed dimension thereof for selectively locking the pin axle 12 in position between the legs 6 and 7. It is to be understood that a rap by a hammer or concentrated thumb pressure will be sufficient to axially dislodge the pin axle 12 for selectively removing same which releases the pulley roller 9 from between the legs 6 and 7 as illustrated in FIG. 2.

In using the above described sheave, a conventional electricians tape 21 is threaded through an electrical cable conduit 22 using a suitable guide 23 in the usual manner. A rope 24 is formed into a loop at 25 intermediate the ends thereof and the loop 25 is secured in any suitable manner to the guide 23 for drawing the rope 24 in doubled condition through the conduit 22, FIG. 4. The loop 25 is pulled through the conduit 22 until it arrives at the cable input end 26 thereof. The sheave 1 is then disassembled as illustrated in FIG. 2 and the loop 25 is placed around the roller 9 whereupon the roller is reassembled between the legs 6 and 7.

An electric cable grip 27 of any suitable design is then secured to the end of the cable 28 to be pulled through the conduit 22. The grip 27 is suitably secured at 29 to the sheave eyelet 5. One end 30 of the rope 24 is anchored or tied to any suitable fixed member 31 and the other or free end portion 32 of the rope is pulled, in the illustrated example by hand at 33. The pulling force exerted on the rope at 32 is doubled at the eyelet 5 due to the pulley advantage obtained and this substantially doubles the usual pulling power available for threading the cable 28 through the conduit 22. During the rope pulling the rounded shapes on the end 11 of the sheave body 2 travels in the direction of the conduit outlet 34 and tends to cause the sheave to be deflected away from any protuberances or interruptions in the conduit 22 avoiding possible jamming. Upon reaching the outlet 34, the sheave 1 is disassembled if desired for removal from the pull rope and the grip 27 is removed from the electrical cable 28 which is then available for splicing at the outlet end 34 in the usual manner.

If desired, the sheave may be threaded through the conduit with the pull rope already engaged therewith, in which case the guide 23 will be secured to the eyelet 5 and the conical section 4 will reduce any tendency to jam.

It is to be understood that while certain forms of this invention have been illustrated and described it is not to be limited to the specific form or arrangement of parts and steps herein described and shows except insofar as such limitations are included in the claims.

What I claim and desire to secure by Letters Patent is:

1. A method of pulling electrical cable through a conduit which includes the steps of:

(a) doubling a pull rope and threading same through the conduit,

(b) engaging said rope in a pulley sheave,

(c) securing said sheave to said cable,

(d) anchoring one end of said rope, and exerting a pull on a free end of said rope for drawing said sheave through said conduit with an increased mechanical advantage.

2. A method of pulling electrical cable through a conduit comprising:

(a) forming a loop intermediate the ends of a pull rope,

(b) threading said rope loop through said conduit from the cable outlet end thereof to the cable inlet end thereof with the rope ends remaining at said cable outlet end,

(c) engaging said loop at said inlet end in a pulley sheave,

(d) securing the cable to said sheave,

(e) anchoring one end of said rope at said outlet end, and exerting a pull on the free end of said rope for drawing said sheave through said conduit with an increased mechanical advantage.

References Cited in the file of this patent UNITED STATES PATENTS 103,587 Eastman May 31, 1877 192,881 Scoville July 10, 1877 371,965 Munsie Oct. 25, 1887 2,532,504 Tapsley Dec. 5, 1950

Claims (1)

1. A METHOD OF PULLING ELECTRICAL CABLE THROUGH A CONDUIT WHICH INCLUDES THE STEPS OF: (A) DOUBLING A PULL ROPE AND THREADING SAME THROUGH THE CONDUIT, (B) ENGAGING SAID ROPE IN A PULLEY SHEAVE, (C) SECURING SAID SHEAVE TO SAID CABLE, (D) ANCHORING ONE END OF SAID ROPE, AND EXERTING A PULL ON A FREE END OF SAID ROPE FOR DRAWING SAID SHEAVE THROUGH SAID CONDUIT WITH AN INCREASED MECHANICAL ADVANTAGE.

Images