The invention generally pertains to special purpose linesman pliers and more specifically to the type that have provisions to prepare a high voltage power transfer cable for electrical connection.
High voltage power transfer cables such as used to transfer over a million volts of electrical power, are generally configured with the high power conductor wires for carrying the electrical power located at the center of the cable, molded within a first layer of insulation. Immediately around the circumference of the exterior of the first layer of insulation, a plurality of neutral conductor wires radially propagating parallel along the length of the cable, the neutral conductor wires being embedded within an outer insulating jacket.
A linesman who is specialized in the trade of prepping, repairing, and connecting high voltage power cables is repetitively required to prepare a cut cable for conductor connection in compromised locations, such as in a trench or vault. High voltage power cables are stiff, large in circumference, and difficult to bend. The conventional tool for this procedure is a so called “linesman pliers”, which incorporate a solid joint with diagonal cutting blades and crimping surfaces, as well as jaws that are used to grip and hold the stripped wires.
The standard high voltage cable prepping process involves a knife, lineman plier, and a linesman performing the following steps using a knife, a snip, and a plier :
The physical force required to rip the neutral wire through the outer insulating jacket is substantial, and often requires a hard yank followed by a braced body pull even if the tear line is pre-scored. Lineman performing this cable prepping task have a history of suffering strain injuries, recurring motion disorders, repetitive stress injuries, and if the grip on the wire is lost suddenly, trauma injuries.
Pliers for cutting insulation jackets, stripping wires, or gripping wires are well known in the art and date back to the 1900's with Inventor J. Irwin's U.S. Pat. No. 924,357 dated June 1909. The opposing pivoting jaws common for most all plier tools were improved for lineman type work. The Irwin improvement included specialized beveled blade element attached to the upper jaw between the pivot axis and the jaw tips. The beveled blade (shown as 15 in patent 924,357) was settable for a cutting depth matching the particular insulation thickness. When used, the insulated wire was captured between the upper and lower jaw, such that when the pliers are rotated circumferentially, the wire is held by the groove (22) in the opposing lower jaw, and the beveled blade (15) circumferentially cuts the insulation. As shown in FIG. 1, Irwin further teaches a ridge (19) on the tip of the upper jaw that presents functionally as a tooth that bites into the insulation to permit the removal, thereby stripping the wire in preparation for electrical connection. The Irwin improvement was aimed to solve the problem of stripping a single core conductor wire covered in one insulation sheath, and would not be workable as used to prepare high voltage cable that has multiple layers of insulation with neutral conductor wires embedded radially around the central main conductor wire.
U.S. Pat. No. 969,339, issued to Chytraus on Sep. 6, 1910, teaches a device for cutting insulation from conductors manually using a pair of knife blades positioned parallel and perpendicularly to the conductor wires, respectively, to perform the cutting. As shown by reference numbers 16 and 21 of FIG. 1 of the patent. U.S. Pat. No. 3,614,905, issued to Bieganski on Oct. 26, 1971, a cable stripping apparatus using a pair of cutters used to apply an annular incision to the outer insulation jacket that is then removed axially away from the remainder of the conductors to expose the underlying conductors. Nothing in the Chytraus patent disclosure or the Bieganski patent suggested a feature of the tool for gripping and ripping the wire through the outer insulating jacket in one motion after performing the annular cutting circumferentially around the high voltage cable. All cutting was performed by blades rather than using the conductor wire itself to rippingly tear through the insulation.
Other prior art attempts to solve the problem of clearing and stripping high voltage cables for electrical connection involve automated machines or power tools to apply the necessary forces to avoid injuring workers, and to speed up production. The ‘Automatic Field Cable Stripper’ having U.S. Pat. No. 6,668,458 by Schoenleber uses a cordless drill to remove the outer insulation jacket to expose the neutral wires. Schoenleber's device solves the problem of prepping a high voltage cable, but requires a power drill to operate.
Looking to more recent prior art examples involving simple hand tools that do not require power assist, an improved Wire-Stripping Pliers by Te-Huang Chiu having patent no. U.S. Pat. No. 7,958,803 teaches a longitudinal stripping of the outer insulation jacket to strip and clear the conductor wires using a jaw fixed blade that is pulled down the cable to cut off the insulation. The Chiu plier as depicted in FIGS. 2 and 3 does not utilize the wire within the insulation to assist in cutting through the insulation, and requires the user to exert the full force without lever advantage when cutting away the insulation.
There is an unfulfilled need for a hand tool that can prep a high voltage cable end for connection. There are tools that can spool up the neutral wire in preparation for connection after the initial stripping or clearing of the outer insulation jacket. To example such a tool, the Cable-Ripping Tool by Jones et. al having Pub. No.: U.S. Pat. No. 2012/0311866 A1 described a tool that spooled the neutral wire after the initial preparations were complete:
Jones et. al. teaches that the winding of the wire on the spool as being performed contemporaneous with the ripping of the neutral wire through the outer insulation jacket, however for the Jones tool to operate, the neutral wire needed to be initially pulled out and cleared 1-¼″ to 2″of the cable's outer insulation jacket as explained in the Jones' specification (starting on page 3, paragraph 0040):
The Jones tool filed in June 2011 identified that pliers were the appropriate tool to pull the neutral wire through the jacket in order to expose the wire adequately for the Jones tool to grip and then spool the neutral wire. However, as discussed above, the standard plier, or even the commonly used lineman type plier requires substantial force to be exerted by the user in order to rip the wire through the outer insulation jacket.
Thus an improved plier, specifically an improved lineman type plier for initially prepping high voltage power transfer cables that removes the outer insulation jacket and clears the neutral wires thereby solving the aforementioned problems is greatly desired.
In the preferred embodiment, an object of the invention is to overcome the shortcomings of the conventional linesman pliers by decreasing the manual forces required to operate when prepping the end of a high voltage power transfer cable, thereby increasing safety, decreasing injury, while improving production.
One advantage of the described invention involves the reduced manual forces that are required to pull the neutral wire through the insulation jacket.
One object of the invention is to incorporate a lever advantage, specifically a protrusion from the lower jaw that is substantially aligned with a cutter that work cooperatively to reduce the required force exerted by the linesman when ripping a neutral wire through an insulating jacket.
Another important object of the preferred embodiment is that it easily and cleanly captures the neutral wire with specialized jaw tips that may be integrally formed within the upper jaw, wherein the upper jaw tip has at least one predator like tooth for biting into or deforming the end of the cable's insulation, to capture a neutral wire, all with minimal manual force applied to the handles, with one hand in one motion.
Another object of the preferred embodiment involves positive securement of the neutral wire with opposing transverse gripping edges located in the upper and lower jaws that receive the captured wire conductor, and positively secures the same with minimal force at the handle by cooperatively deforming the wire with a sharp bend between the transverse gripping edges that compress the sharp bend such that the hold on the conductor wire is maintained with minimal opposing force at the handles as applied by the user.
Yet another object of the preferred embodiment is the circumferential cutting feature that is performed by a robust open jaw design which includes a replaceable scoring blade and guard in the lower jaw to facilitate circumferential scoring or cutting of the insulation jacket without the need of a knife.
Another advantage of the preferred embodiment involves retention of full function as the traditional tool used by linesmen. The traditional functionality of the plier include the wire cutter and wire crimper, which remain in traditional function and location. The improved lineman plier's features and elements do not conflict with either the wire cutter's use or the crimper's functionality as located immediately fore and aft of the pivot point,
Yet another object of the preferred embodiment is that the functionality and performance of the plier is greatly increased at little expense to the manufacturing costs.
These and other objects and advantages of the present invention will become apparent from the subsequent detailed description of the preferred embodiment and the appended claims taken in conjunction with the accompanying drawings.
An embodiment of the invention will now be described by way of illustrative drawings from different perspectives as depicted in the accompanying figures, in which;
The best mode for carrying out the cable preparation tool is disclosed in terms of a preferred embodiment for an improved plier 10 as depicted in
The first body 31 having a handle 20 on one end, with an upper jaw 30 on the other, the upper jaw 30 having at least one upper transverse gripping edge 34 and at least one upper jaw tip 33, the upper jaw tip 33 having at least one tooth 32 integrally formed therefrom. In other embodiments the tooth 32 is a discrete component that removably engages the upper jaw tip 33 and is a replaceable component of the improved plies 10. The upper jaw 30 further includes an oblong void 60 in which a blade 54 (shown in
As depicted illustratively in
The second body 41 having a handle 20 on one end, a lower jaw 40 on the other, the lower jaw 40 having at least one lower transverse gripping edge 46, at least one lower jaw tip 43 and a cutter 44 integrally formed therefrom, and at least one protrusion 42 projecting externally from the lower jaw 40 and substantially aligned with the cutter 44.
As depicted in
This improved plier 10 as depicted in its preferred right hand embodiment in
The preferred cutter 44 as shown in
As shown in
In the preferred embodiment, the force exerted on the handles 20 is multiplied several times by the mechanical advantage of the protrusion 42, thereby significantly reducing the physical forces required by the lineman when ripping out a stripped conductor wire. As mentioned above, the size of the protrusion 42 may be increased or decreased to adjust the desired length of conductor wire to be pulled and stripped from the cable. The larger the radius of the protrusion 42, the more of the neutral wire is ripped through the outer insulation jacket.
As shown by illustrative close up view in
While the preferred embodiment of the invention has been described in illustrative detail in the accompanying drawings, it is not to be limited to such details, since many changes and modifications may be made to the invention without departing from the spirit and scope thereof. Hence, it is described to cover any and all modifications and forms which may come within the language and scope of the appended claims.
This application claims priority under 35 U.S.C. §119(e)(1) to U.S. Ser. No. 61/826,478, filed May 22, 2013, which is hereby incorporated by reference in its entirety.
Number | Date | Country | |
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61826478 | May 2013 | US |