Abstract:
The extensible leash system comprises a rope and a leash extending from the rope. A weight system including an incremental weight device is suspended to the rope and has a first, second, third and fourth weights mounted therein. There is also provided a mechanism for raising the first, second, third and fourth weights with the rope in sequence according to a first distance interval along the rope between the first and second weights, according to a second distance interval along the rope between the second and third weights, and according to a third distance interval along the rope between the third and fourth weights, wherein a relation between the weight extents of the first, second, third and fourth weights, and the first, second and third distance intervals represents an exponential increase in a restraining action on the rope and the leash.

Description:
FIELD OF THE INVENTION  
       [0001]     This invention pertains to tethering devices, and more particularly it pertains to an extensible animal leash having its secured end attached to an incrementally-increasing weight system.  
       BACKGROUND OF THE INVENTION  
       [0002]     There are several reasons for keeping an animal leash under a slight tension at all times. First, an animal tied to a leash in a backyard for example, moves around and back and forth within the leash&#39;s range. When the leash has slack segments in it, it tends to become entangled around its support structure and around nearby objects. More important, the leash can become entangled around one of the animal&#39;s legs or other body part, and can entrap the animal in a precarious position for long periods of time. A slight tension in the leash keeps it free of knots and snares. A second reason for keeping an animal leash under a slight tension is to lessen the impact of a tight-leash stop on the animal&#39;s collar.  
         [0003]     In the past, several devices were developed to apply a slight tension on a leash or on other tethering cords used for retaining horses, boats and even for preventing a child from wandering away from a supervised playground.  
         [0004]     Examples of these prior art devices are described in the following US Patents. These documents are divided in three groups. The documents in the first group describe tethering cords passing over a sheave or a similar rope guide mounted in a vertical support structure. In each case, a single weight is suspended to the cord inside the vertical structure. As the cord is pulled away from the vertical structure, the weight is lifted, thereby applying a tension on the cord. This first arrangement is described in the following patents. 
    U.S. Pat. No. 124,532 issued to C. F. Barnard on Mar. 12, 1872;     U.S. Pat. No. 167,263 issued to T. Maguire on Aug. 31, 1875;     U.S. Pat. No. 183,677 issued to J. L. Jackson on Oct. 24, 1876;     U.S. Pat. No. 750,141 issued to W. J. Willey on Jan. 19, 1904.    
 
         [0009]     One improvement to the above-described arrangement has been to incorporate a compression spring around the cord, between the rope guide and the weight, to absorb the impact of the weight reaching the end of its travel. This type of tethering device is illustrated in the following documents: 
    U.S. Pat. No. 757,882 issued to T. C. Butterworth on Apr. 19, 1904;     U.S. Pat. No. 3,189,004 issued to F. Sinclair on Jun. 15, 1965.    
 
         [0012]     In yet another improvement to tethering devices, a mechanical advantage has been introduced in the restrainer portion of each device. A pulley block is attached to the weight and the cord forms a loop that is threaded into the pulley block with its fixed end tied to the upper end of the vertical structure. The weight is thereby suspended to two segments of the cord whereby the total cord extension is twice as long as the weight&#39;s travel distance along the vertical structure. This type of tethering device is illustrated in the following patents; 
    U.S. Pat. No. 215,730 issued to J. A. Fox et al. on May 27, 1879.     U.S. Pat. No. 550,620 issued to J. C. Jones on Dec. 3, 1895;     U.S. Pat. No. 2,725,853 issued to J. Nordheim on Dec. 6, 1955;     U.S. Pat. No. 4,747,372 issued to M. Terry et al. on May 31, 1988.    
 
         [0017]     The system described in U.S. Pat. No. 550,620 in particular, differs slightly from the other devices in the latter group because it has two loops in series along the cord and two weight-and-block arrangements respectively mounted in these loops. One of the weights is heavier than the other, and is lifted last for increasing the pulling resistance on the cord incrementally.  
         [0018]     It is believed that when one discrete change in tension is applied to a tether rope at a specific location, or when two changes in tension are applied to a tether rope at a fixed distance interval between each other, an animal can learn the locations where the tension increases in the rope along the rope&#39;s range. An animal tied to the rope can thereby anticipate and get accustomed to these changes in tension, and can still run to the end of the rope with considerable momentum.  
         [0019]     Although the tethering devices of the prior art deserve undeniable merits, it is believed that a need still exists for a tethering device which is more efficient than the prior art installations for dissuading an animal from attempting to reach the end of its leash.  
       SUMMARY OF THE INVENTION  
       [0020]     In the present invention, however, there is provided an incremental weight device that can be used for increasing the pulling resistance on a leash in an incremental and irregular manner, and for transmitting authoritative commands to the animal being restrained. Also, it has been found that such incremental and irregular additions of weights to the leash can prevent an animal from anticipating the increases in tension.  
         [0021]     Unexpected advantages of the present invention are more apparent and better explained when the incremental weight device is described in an animal leash environment. Accordingly, in a first aspect of the present invention, there is provided an extensible leash system comprising a rope and a leash extending from this rope. A weight system is suspended to the rope. The weight system has a first, second and third weights mounted therein. There is also provided a mechanism for raising the first, second and third weights in sequence according to a first distance interval along the rope between the first and second weights, and according to a second distance interval along the rope between the second and third weights, wherein the second distance interval is shorter than the first distance interval.  
         [0022]     Because the application of the third weight to the leash is effected at a shorter distance interval than the second weight, the restraining action applied to the leash transmits a command of firmness to the restrained animal to better dissuade the animal from pulling further.  
         [0023]     In another aspect of the present invention, there is provided a fourth weight in the weight system. The aforesaid mechanism has means for raising the fourth weight in sequence according to a third distance interval along the rope between the third and fourth weights. The third distance interval is similar to the second distance interval, and a sum of the second and third distance intervals is less than the first distance interval.  
         [0024]     In yet another aspect of the present invention, the weight extents of the first, second, third and fourth weights in relation with the first, second and third distance intervals represent an exponential increase of a restraining action on the rope and the leash.  
         [0025]     Again, the exponential application of weights to the leash near the end of the leash&#39;s range provides a stronger command of firmness and determination to the restrained animal to further dissuade the more stubborn animals from pulling on the leash.  
         [0026]     Still another feature of the leash system according to the present invention is that it is susceptible of a low cost of manufacture with regard to both materials and labour, and which accordingly is then susceptible of low prices of sale to the consumer, thereby making such leash system economically available to the public.  
         [0027]     It yet a further aspect of the present invention, the incremental weight device, in its most basic form, is described as follows. The incremental weight device comprises a plurality of tubular sections of different sizes telescopically mounted inside each other. These tubular sections are extensible from within each other. Each of the tubular sections has an upper end, a lower end, a cylindrical surface, and a circular shoulder on its lower end protruding from its cylindrical surface. The smallest tubular section has an eyelet on its upper end. Each of the tubular sections has on its upper end, a circular lip extending inward relative to its cylindrical surface. Each of the lips has a dimension to interfere with the shoulder on the next smaller tubular section for preventing separation of the tubular sections from each other when they are extended relative to each other.  
         [0028]     This brief summary has been provided so that the nature of the invention may be understood quickly. A more complete understanding of the invention can be obtained by reference to the following detailed description of the preferred embodiments thereof in connection with the attached drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0029]     Two embodiments of the present invention are illustrated in the accompanying drawings, in which like numerals denote like parts throughout the several views, and in which:  
         [0030]      FIG. 1  is a partial cutaway view of a column comprised in the leash system according a first preferred embodiment of the present invention;  
         [0031]      FIG. 2  is a cross-section and exploded view of one of the telescopic sections mounted in the incremental weight device comprised in the preferred leash system;  
         [0032]      FIG. 3  is a cross-section view of the incremental weight device comprised in the preferred leash system;  
         [0033]      FIG. 4  is a plan view of one of the load units included in the incremental weight device;  
         [0034]      FIGS. 5 and 6  are cross-section views of the column comprised in the preferred leash system, showing the weights therein in two different positions;  
         [0035]      FIG. 7  is an enlarged cross-section view of the cap mounted on the column shown in  FIGS. 5 and 6 ;  
         [0036]      FIG. 8  is a cross-section view of the cap as seen along line  8 - 8  in  FIG. 7 ;  
         [0037]      FIG. 9  is a plan view of the preferred leash system showing different shaded areas indicating regions of different tensions in the leash;  
         [0038]      FIG. 10  is a graph showing preferred additions of weights to the secured end of the leash in the preferred leash system;  
         [0039]      FIG. 11  is a cutaway side view illustration of the incremental weight device mounted inside an exercising apparatus. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0040]     While the incremental weight device according to the present invention is susceptible of embodiment in many different forms, there are shown in the drawings and will be described in details herein two specific embodiments, with the understanding that the present disclosure is to be considered as an example of the principles of the invention and is not intended to limit the invention to the embodiments illustrated and described. The incremental weight device is first described and illustrated in  FIGS. 1-10  in an animal leash environment. A second preferred embodiment describes the incremental weigh device mounted in an exercising apparatus. This second preferred embodiment is illustrated in  FIG. 11 .  
         [0041]     Referring to  FIG. 1 , the preferred leash tensioning system will be described broadly. The preferred leash tensioning system comprises a hollow column  20  having a base plate  22 , a cap  24  and a conduit  26  on the cap. A rope  28  extends from that conduit  26  and extends into, constitutes, or is connected to, a leash  28 ′ to which an animal, such as a dog  30  can be attached.  
         [0042]     The base plate  22  is preferably held to the ground by anchor bolts  32  as illustrated, by one or more sand bags or by other ballast material or object.  
         [0043]     The conduit  26  is preferably affixed to the cap  24  by means of a swivel joint  34  to allow the conduit  26  to rotate about a vertical axis.  
         [0044]     The hollow column  20  has two vertical compartments  40 ,  42  therein separated by a partition  44 . A first weight  46  is mounted in the first compartment  40  and is engaged to the rope  28  by means of a first pulley block  48 . A second weight  50  is mounted in the second compartment  42  and is also engaged to the rope  28  by means of a second pulley block  48 . The cap  24  encloses a pulley system therein through which the rope is threaded.  
         [0045]     A stopper  52  is preferably installed on the rope  28  adjacent to the conduit  26  when the weights  46 ,  50  are at rest on the base plate  22 . The stopper  52  prevents the rope  28  from taking some slack inside the column  20  and from disengaging from the pulley system.  
         [0046]     Preferably, the column  20  is made of two separate longitudinal sections. An upper section  60  is telescopically engaged over, and movable along, a base section  62 , to adjust the height of the column  20  and to satisfy certain installation conditions. The adjustment of the height of the column  20  is preferably effected by means of bolts  64  or pins extending through the wall of the upper section  60  and into a corresponding set of holes  66  in the base section  62 .  
         [0047]     Although a dog is mentioned herein and is illustrated in  FIG. 1 , the leash system according to the present invention can be made to accommodate other animals such as a horse or a variety of zoo animals. The leash system can also be reduced in size and used indoors, with a ballast ring on its base, to retain a cat or a hamster for example.  
         [0048]     Referring now to  FIGS. 2-4 , the preferred structure of the second weight  50  will be described. The second weight  50  is also referred to herein as the incremental weight device according to the present invention because its general arrangement and variations represent the main focus of the present invention.  
         [0049]     The incremental weight device  50  according to the first preferred arrangement has a telescopic structure which is made of three tubular sections  70 ,  72 ,  74  with each section sliding into a larger one such as a telescope. The second weight  50  is also referred to herein as the incremental weight device because it is made of different weights that are added to each other as the telescopic structure thereof is extended.  
         [0050]     Each section  70 ,  72  or  74  has an outside circular shoulder  76  on its lower end and an inside circular lip  78  on its upper end. The shoulder  76  of one section engages with the lip  78  of the next larger section to retain the sections  70 ,  72  inside the section  74 . The smaller section  70  has a eyelet  80  on its upper end, to which can be fastened a pulley block  48 .  
         [0051]     Each tubular section  70 ,  72  or  74  has a plug  82  on its lower end. The projection around the base of this plug  82  constitutes the aforesaid shoulder  76 . When the plug  82  on one section is removed, the opening in the lower end of that section is wide enough to accept the next-smaller tubular section there through with its plug  82  mounted thereon.  
         [0052]     The plug  82  in each section has a hollow portion  84  therein having an outside surface and an outside thread  86  on that outside surface. Each tubular section has a corresponding inside thread  88  on its inside lower portion. In use, the plug  82  is engaged with the inside thread  88 . The hollow portion  84  of the plug constitutes a cavity for receiving one or more load units  90 . The rim of the hollow portion  84  of each plug also constitutes a stopper  92  on which rests the plug  82  of a smaller tubular section when this telescopic weight  50  is in a collapsed mode.  
         [0053]     Although a threaded engagement  86 ,  88  to retain the plug  82  to a tubular section  70 ,  72  or  74  is mentioned herein, it will be appreciated that other fastening means can be used to accomplish the same result.  
         [0054]     The tubular sections  70 ,  72 ,  74  are also referred to herein as the first, second and third telescoping weights. In use, the first section  70  of the three telescoping weights is lifted first. After an initial extension of the first section  70 , corresponding substantially to the length of that section, the shoulder  76  on the first section  70  engages with the lip  78  on the second section  72  to entrain the second section  72  in unison. The third section  74  is similarly engaged to the second section  72  following a displacement of the second section  72  relative to the third section  74 .  
         [0055]     Each load unit  90  has a torus-like shape, a basic thickness, an outside diameter ‘A’ and an inside diameter ‘B’. The outside diameter ‘A’ is selected such that the load unit fits inside the hollow portion  84  of a particular plug  82 . The inside diameter ‘B’ is determined according to the desired weight extent of a particular load unit  90 . In the preferred embodiment of an animal leash system, each tubular section  70 ,  72  or  74  has a similar weight extent.  
         [0056]     It should be noted that the first weight  46  has a similar structure as the first telescoping weight  70 . However, the first telescoping weight  70  is heavier than the first weight  46  such that the first weight  46  is lifted first.  
         [0057]     The weight extent of the first weight  46  is selected to provide a pull force on the rope  28  which is sufficient to pull back the rope  28  inside the column  20 , and to keep the rope  28  relatively taut, but should be insufficient to frustrate an animal walking, standing or laying within the range provided by the displacement of this first weight  46 .  
         [0058]     The weight extent of the first telescoping weight  70  should be sufficient to hinder the displacement of an animal tied to the leash  28 ′, and the weight extents of the second and third telescoping weights  72 ,  74  should be such as to make it difficult for the animal to move further. For example, the weight extents of the first, second and third telescoping weights  70 ,  72 ,  74  can equal or exceed the weight of the animal to be restrained by the leash system.  
         [0059]     The extensions of the sections  70 ,  72 ,  74  are preferably of equal lengths. Although three sections  70 ,  72 ,  74  are illustrated in the incremental weight device  50 , it will be understood that two or more than three sections can be used. The total extension of the incremental weight device  50  is also selected such that it is less than the travel distance of the first weight  46  along the column  20 .  
         [0060]     The provision of removable plugs  82  on the tubular sections  70 ,  72 , 74  makes it particularly easy to assemble the incremental weight device  50 , or to vary the quantity of load units  90  in each section.  
         [0061]     Referring now to  FIGS. 5 and 6 , the operation of the preferred leash system will be described. The rope  28  is guided into the conduit  26  and under an idler pulley  100 , inside the cap  24  of the column  20 . The rope  28  is suspended to a first and second support sheaves  102 ,  104  and forms a first loop  106  between the first and second support sheaves  102 ,  104 . This first loop  106  extends into the first compartment  40 . The first loop  106  is threaded into the pulley block  48  on the first weight  46 .  
         [0062]     The rope  28  extends over the second support sheave  104  and has its secured end tied to a holed bracket  108  inside the cap  24  of the column  20 . The rope  28  forms a second loop  110  between the second support sheave  104  and the holed bracket  108 . The second loop  110  extends down into the second compartment  42 , and is threaded into the pulley block  48  on the incremental weight device  50 .  
         [0063]     In use, when the slack in the leash is pulled tight, and the rope  28  is pulled out of the column  20 , the first loop  106  shortens first, thereby lifting the first weight  46  off the base plate  22  and upward along the first compartment  40 . A bumper  112  is mounted inside the cap  24 , inline with the trajectory of the pulley block  48  on the first weight  46 . This bumper  112  limits the upward movement of the first weight  46 .  
         [0064]     When the first weight  46  reaches its upper limit, at bumper  112 , as illustrated in  FIG. 6 , the tension in the rope  28  causes the second loop  110  to shorten up, thereby pulling the incremental weight device  50  upward. The first section  70  of the incremental weight device  50  extends first and entrains the second and third sections  72 ,  74  in sequence. When the pulley block  48  on the incremental weight device  50  reaches the cap  24  of the column  20 , it comes in contact with a shock absorber  114  that is affixed to the cap  24 . The shock absorber  114  further reduces the force of tight-leash impacts on the collar of the restrained animal.  
         [0065]     As seen in  FIGS. 5 and 6 , both compartments  40 ,  42  are separated by an extensible partition  44 . This partition consists of a pair of guide plates  120  affixed to the base section  62  and a central plate  122  affixed to the upper section  60 . The central plate  122  is positioned to slide between both guide plates  120 .  
         [0066]     In installations where the column  20  has a fixed height and is not exposed to difficult environment, this column can be fabricated from a H-beam (not shown) for example, where the web of the beam constitutes the partition  44  and the cap  24  is affixed to the flanges of the beam. In that case, both compartments  40 ,  42  are exposed to the sides of the column. Also, the column can be fabricated with a pair of round tubing for examples. It will also be appreciated that the column  20  and the weights  46  and  50  can be fabricated with metal or plastic, according to the conditions of use of the leash system.  
         [0067]     As mentioned before, the cap  24  encloses the idler pulley  100 , the first and second support sheaves  102 ,  104 , the bumper  112  and the shock absorber  114 , as illustrated in  FIGS. 7 and 8 . The idler pulley and sheaves are supported on respective shaft  136  and are kept aligned with each other by means of spacer sleeves  138  mounted on these shafts  136 . The bumper  112  is supported on a structural bar  140  extending across the sides of the cap  24 .  
         [0068]     The preferred shock absorber  114  comprises a spring  142  that is mounted inside telescoping and guiding sleeves  144 , to prevent the spring from buckling. One or more spacers  146  are affixed to the inside walls of the cap  24  to locate the cap over the upper section  60  of the column, and to facilitate the bolting of the cap  24  to the upper section  60 . Because the pulley mechanism is mounted inside the cap  24 , and the cap is separable from the upper section  60 , the entire column  20  is relatively easy to manufacture, to assemble and to maintain.  
         [0069]     Referring now to  FIGS. 9 and 10 , the principal advantage of the preferred leash system will be described. In both illustrations, the pulling resistance on the leash  28 ′ is represented over the range of the leash. The distance ‘C’ represents the length of slack segment  150  in the leash. The distance ‘D’ represents the span corresponding to the vertical measure travelled by the first weight  46 , and the distance ‘E’ represents the span corresponding to the vertical measure travelled by the incremental weight device  50 . The vertical measures ‘D’ and ‘E’ are similar distances. The different shades of gray in the span ‘E’ in  FIG. 9 , and the step-like portion in the span ‘E’ in the graph of  FIG. 10  represent the addition of the weights  70 ,  72 ,  74  during the extension of the incremental weight device  50 . The heavier shade in  FIG. 9  and the last step in the graph of  FIG. 10  shows the compression of the spring  142  in the shock absorber  114 .  
         [0070]     While the length of a rope ‘D’ between the first weight  46  and the first telescoping weight  70  is somewhat predictable by an animal, the additions of the other telescoping weights  72  and  74  come in rapid succession relative to the distance ‘D’. Their additions to the leash&#39;s resistance are therefore more difficult to anticipate. For this reason basically, an animal pulling on the preferred leash system generally turns back at the application of the second telescoping weight  72  or the third telescoping weight  74 .  
         [0071]     Referring particularly to  FIG. 9 , one can understand that the addition of weights to the leash  28  is effected in an exponential-like manner as shown by curve  152 . Such an exponential addition of weight transmits a command of firmness to the leash  28 ′. It has been found that such command has a dissuading effect on animals. An animal tied to this leash realizes the rapid succession of increases in tension in the region ‘E’ and soon learns to avoid this region.  
         [0072]     Because of the possibility to add load units  90  inside each section of the incremental weight device  50 , it is possible to change the slope of the curve  152  to increase the firmness in the leash to work best with the character of the animal to be restrained.  
         [0073]     While the incremental weight device  50  according to the present invention has been described in use in an animal leash apparatus, it will be appreciated that this incremental weight device has numerous other applications that are only limited by the imagination of the user. In an attempt to demonstrate these other applications,  FIG. 11  has been inserted herein.  FIG. 11  illustrates an exercising apparatus  160  that can be used to develop the arms, shoulders and thorax muscles of an athlete for examples.  
         [0074]     The exercising apparatus comprises a base  162  which can be bolted to a floor, a vertical hollow column  164  mounted to the base  162 , and a cap  166  mounted on the top of the column  164 . A rope  168  extends through the cap  166 . The rope  168  has a first end outside the column and a handle  170  is attached to that first end. An incremental weight device  172  is mounted inside the column  164 . The second end of the rope  168  is attached to the incremental weight device  172 . The second incremental weight device  172  differs slightly from the first incremental weight device  50  as previously described because it contains four telescoping sections instead of three. In use, the incremental weight device  172  is extended as the handle  170  is pulled away from the column  164 . The pulling resistance on the handle  170  is thereby increased incrementally as the handle is moved away from the column  164 .  
         [0075]     The person skilled in the art will appreciate that the apparatus illustrated in the drawings can also be used as mooring devices for retaining small boats to a dock for example.  
         [0076]     As to other manner of usage and operation of the present invention, the same should be apparent from the above description and accompanying drawings, and accordingly, no further discussion relative to the manner of usage and operation is provided.  
         [0077]     While two embodiments of the present invention have been illustrated in the accompanying drawings and described herein above, it will be appreciated by those skilled in the art that various modifications, alternate constructions and equivalents may be employed without departing from the true spirit and scope of the invention. Therefore, the above description and the illustrations should not be construed as limiting the scope of the invention which is defined by the appended claims.