1. Field of the Invention
The present invention relates to a calibrated mechanical winch, and more particularly, but not by way of limitation, to a calibrated mechanical winch and method of manufacture thereof, the winch being adapted for stretching and tightening wire and/or other cables, tethers and the like by utilization of a manually operable device allowing for the user to ascertain the general level of tension applied to the cable or other tether being acted upon during the stretching operation.
2. History of the Related Art
Many devices have been used for tensioning cables, wires and other tethers over the decades. A common manual approach to tightening wire is seen in the area of fencing. Farm land generally spans many miles and requires a variety of fenced sections that may be manually installed with available equipment. For example, barbed wire is common in various states, such as Texas, and many varieties have been used by farmers, ranchers and the like. The manual stretching of barbed wire between two fence posts is a common practice, even today. Fortunately, the manual stretching of such wire is often facilitated by mechanical winches actuatable by the user. One such mechanical winch is conventionally known as a “come along.” This device allows the user to grasp one end of a strand of fencing, such as a barbed wire strand, and apply a manual force thereto relative to a fixed object and/or another strand of wire. While handy to use, the use of come along type devices has certain disadvantages. One distinct disadvantage is the inability to readily ascertain, with much accuracy, the general level of tension being applied to the wire without some form of independent tension measuring device or method. For this reason, it is common to simply hit the tensioned wire with a metal object, such as a screwdriver or similar item, to ascertain the vibrational tone of the wire and audibly determine if appropriate tightness has been applied thereto. This approach, though common, does not provide precise information as to the tension such that it can be accurately repeated along multiple strands of a fenced section. Uniform tension among the multiple strands of a fenced section is, however, very important and therefore a device providing stretching and such information would prove useful.
The tensioning of wire strands is not the only application where cables, tethers and wires must be stretched. When erecting vertical structures, such as radio or television antenna towers, wire stays or the like are often used. Tensioning devices must be incorporated in such applications in order to avoid the potential risk of property damage and personal injury should the tensioning of the cable or the wire strand fall outside of the engineering specification. While the failure of a wire or cable support for a tower is generally much more catastrophic than the failure of a length of fencing wire, there are many considerations that are common between the two. For example, due to the thermal coefficient of expansion, the ambient air temperature has a direct bearing on the appropriate wire tension. Wires constructed of metallic materials inherently have a known thermal coefficient of expansion. The wire will thus expand and contract as the ambient temperature rises or falls. If, for example, wire is installed in the heat of the summer at a select tension, when the ambient temperature drops in the autumn and winter months, the metal in the wire will contract thereby increasing the load on the wire; possibly resulting in the wire breaking. For this reason, it would be important to observe the degree of tension, relative to the ambient temperature, placed upon a wire, cable, tether, or the like during the tensioning process.
Various approaches to measuring tensioning of wire and cable have been addressed over the years. For example, U.S. Pat. No. 3,791,210 to Taylor discloses a tension measuring device that measures cable tension as a function of deflection of its component members. U.S. Pat. No. 4,408,925 to Louie discloses a turnbuckle tensioner which applies tension to a cable through the deflection of a series of belleville washers. U.S. Pat. No. 5,485,762 to Rothman discloses a cable tensioner which uses a linear ratchet to apply tension to a cable. U.S. Pat. No. 6,279,415 to Chance, et al. discloses a cable tensioner that utilizes a linear spring to apply tension to a cable. However, none of these inventions contemplate a come-along style mechanical winch that is calibrated to provide a accurate measurement of cable tension while the wire or cable is being stretched by a user.
It would thus be an advantage to provide a manual winch capable of indicating the degree of tension being applied a wire or cable during a manual tensioning procedure. It would be a further advantage for such a device to be in a configuration that works in a fashion to similar come along devices that are commonly used and well known in the farming and ranching industry. The present invention provides such an improvement by utilizing a mechanical winch having a tension calibration feature incorporated therewith.
The present invention relates to a calibrated mechanical winch. In one aspect, the invention relates to a hand-held mechanical winch of the type operable for stretching wire and/or cables. The mechanical winch comprises a manually actuated spool disposed within a frame and connected thereto by a plurality of springs. A length of cable or wire is operably coupled to the spool, and a brake axle is located a fixed distance from the spool. Successive actuation of the spool support assembly applies incrementally increasing tension to the length of cable or wire and causes compression of the plurality of springs in an amount proportional to the tension applied to the length of cable or wire.
In another aspect, the invention relates to a method of manufacturing a calibrated mechanical winch. The method of manufacturing comprises forming a frame and locating a spool support assembly within the frame. The spool support assembly is then connected to the frame with a plurality of springs, and a length of cable or wire is connected to the spool support assembly. A handle is connected to the spool support assembly, wherein successive actuation of the handle applies incrementally increasing tension to the length of cable or wire and causes compression of the plurality of springs in an amount proportional to the tension applied to the length of cable or wire.
In another aspect, the invention relates to a method of tensioning a cable or wire. The method comprises providing a hand-held mechanical winch, connecting a first coupler to a fixed support, and connecting a second coupler to a length of cable or wire to be tensioned. Tension is then applied to the length of cable or wire which compresses a plurality of springs located in the hand-held mechanical winch. The tension applied to the length of cable or wire is then measured as a function of compression of the plurality of springs.
In another aspect, the invention relates to a calibrated mechanical winch having an adjustable limit switch for further assisting in ascertaining a pre-determined level of tension applied to a cable or wire. The limit switch is initially secured underneath a stop and is spring-biased to rotate when the stop is removed. The stop is able to move responsive to the compression of springs disposed in the frame of the mechanical winch. When enough tension is applied to the cable or wire to compress the springs a sufficient distance, the stop loses contact with the limit switch. The spring then induces the limit switch to rotate. Such motion alerts the user to when a desired level of tension has been reached.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several embodiments of the invention and, together with the description, serve to explain principles of the invention.
Reference is now made in detail to exemplary embodiments of the present invention illustrated in the accompanying drawings. Wherever possible, the same reference numerals are used throughout the drawings to refer to the same or similar parts.
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Prior to use, the limit switch 80 must be adjusted for the amount of tension to be applied to the wire 74. This is accomplished by adjusting the adjustable threaded member 90 to have an exposed length appropriate for the amount of force to be applied to the wire 74. By way of example, if a large amount of tension is to be applied to the wire 74, then the adjustable threaded member 90 would be threaded out of the limit switch 80, thereby increasing the exposed length of the adjustable threaded member 90. This results in more tension being applied to the wire 74 before the limit switch 80 is released. On the other hand, if a smaller amount of tension is to be applied to the wire 74, then the adjustable threaded member 90 would be threaded into the limit switch 80, thereby reducing the exposed length of the adjustable threaded member 90. This results in less tension being applied to the wire 74 before the limit switch 80 is released.
Next, the limit switch 80 must be set, this is accomplished by rotating the limit switch 80 about the limit switch axle 82 in a direction opposite that defined by the arrow 86. Such rotation causes the spring 84 to bias the limit switch 80 to rotate in the direction denoted by the arrow 86. During setting, the limit switch 80 may slide laterally across the limit switch axle 82 so as to allow the adjustable threaded member 90 to be passed underneath the stop 88. The stop 88 restrains the tendency of the limit switch 80 to rotate in the direction denoted by the arrow 86.
During operation, a load is applied to the wire 74 through successive actuation of the handle 38. As previously discussed, as the load applied to the wire 74 increases, the spool support assembly 34 tends to slide, within the exterior frame 12, in a direction denoted by arrow 104 as shown in
In the event that the operator desires to relieve the load applied to the wire 74, the operator simply fully actuates the handle 38 in the direction depicted by the arrow 100. If a large amount of load has been applied to the wire 74, it may be necessary to actuate the drive pawl 50 so as to disengage the drive pawl 50 from the ratchet wheel 46. Such disengagement will allow the handle to rotate independently of the spool without applying any additional load to the wire 74. When the handle has been fully actuated in the direction depicted by the arrow 100, the drive pawl contacts the brake pawl 58. The interaction between the drive pawl 50 and the brake pawl 58 causes the brake pawl 58 to also become disengaged from the ratchet wheel 46. The disengagement of both the drive pawl 50 and the brake pawl 58 allows the spool 36 to rotate freely and relieves the load applied to the wire 74.
It is further contemplated that the springs 64A and 64B may be interchangeable to allow use of the mechanical winch 10 with springs of varying stiffness. This functionality allows the mechanical winch 10 to measure a wider range of force, and adapts the device for use in a wide array of applications. Interchanging springs 64A and 64B may be accomplished through any appropriate means, but as currently contemplated, may be accomplished by removing the T-nuts 24A and 24B and the spring stops 62A and 62B. If the scale 76 is calibrated to measure force, then the scale 76 may also be interchangeable and constitute more than the indicia shown in
Although various embodiments of the method and apparatus of the present invention have been illustrated in the accompanying Drawings and described in the foregoing Detailed Description, it will be understood that the invention is not limited to the embodiments disclosed, but is capable of numerous rearrangements, modifications, and substitutions without departing from the spirit and scope of the invention as set forth in the foregoing specification and following claims.
This application claims priority to, and incorporates by reference the entire disclosure of, U.S. Provisional Patent Application 61/123,124, filed Apr. 3, 2008, entitled CALIBRATED MECHANICAL WINCH AND METHOD OF MANUFACTURE.
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Number | Date | Country | |
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20090250543 A1 | Oct 2009 | US |
Number | Date | Country | |
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61123124 | Apr 2008 | US |