Abstract:
Self-tightening snow chain for attachment to a vehicle wheel to provide traction. The preferred self-tightening snow chain includes a traction cable and a tensioning device including a housing having a top including a set of housing teeth, a bottom and at least one aperture; a lever interconnected to the housing; a ratchet spool within the housing having a set of ratchet teeth that mate with the housing teeth and a channel between upper and under surfaces to receive a cord that is interconnected with the ratchet spool; a tension spring that places a bias on the ratchet spool toward a wind-up direction; and a wave spring. A preferred tensioning device includes a cord sub-unit having two knobs, one on each end, and a grommet encircling the cord. A method of assembling the tensioning device is also disclosed.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to snow chains, particularly, snow chains that self-tighten to ensure proper fit. More particularly, the present invention relates to self-tightening snow chains having a tensioning device including a winding device and a tensioning cord, the snow chains having a tensioned mode when secured for use on a wheel of a land vehicle and a separate extended mode, wherein the tensioning cord, interconnected with the winding device is released to extend away from the winding device to permit the snow chain to be easily engaged with the wheel of the land vehicle prior to securing the snow chain to the wheel. In alternate embodiments, the present invention relates to self-tightening snow chains that self-tighten when a plurality of cords are tensioned by a single winding device. In further embodiments, the present invention relates to a tensioning device for a snow chain that places a spring bias upon a tensioning cord or a plurality of tensioning cords and/or is resistant to infiltration of dirt, debris and moisture. Methods of providing and using these inventions are also disclosed. 
     BACKGROUND OF THE DISCLOSURE 
     Self-tightening snow chains have been used to provide vehicles with improved traction when driving on irregular surfaces where poorer traction is anticipated (i.e. ice or snow covered surfaces, off-road or backcountry terrains). Numerous states require the use of snow chain under certain weather conditions to mitigate potential hazards. Most models of snow chains require retightening after initial chain installation, where all of the wheel chains need to be retightened after the vehicle has been slowly driven forward or backward. It is essential that snow chains fit properly to obtain proper performance and increase durability. Having to retighten the cables is burdensome for the user and has costly consequences if forgotten or neglected. 
     Because proper fit of the snow chains is so essential, self-tightening snow chains have been developed. One of these devices is disclosed in U.S. Pat. No. 6,213,421 to Franklin. The Franklin patent discloses a clamping lock for a traction device. The lock has a single clamping rope connected to a winding device within a housing. The winding device is pre-tensioned in the wind-up direction. Toothing is provided laterally around the winding device. There is an actuating lever attached to the housing that has three positions: a first catch position, which allows the clamping rope to move in or out of the housing; a second wind-up position, which unlocks the rope so it may move into the housing, thereby tightening the clamping rope; and a third locked position wherein the clamping rope is locked in its current position. The lever controls a pawl. Whether or not the clamping rope may be pulled in or out of the housing depends on whether the pawl is engaged with the teeth on the winding device. 
     Self-tightening snow chains having tensioning devices of this kind are difficult to secure to a wheel of a vehicle with two hands. A user may need to let go of the cord in order to better grip the tensioning device or grab the corresponding hook on the snow chain. In order to prevent the cord from being pulled back into the housing, the user must lock the cord in both directions to keep the cord in the extended position. Then, the cord would need to be unlocked to extend further, again requiring releasing either the cord or the corresponding hook. Additionally, self-tightening snow chain tensioning devices that can only tighten one cord are less cost effective because numerous self-tightening tensioning devices are required on each snow chain to tighten each cord. 
     Of further concern, self-tightening snow chain tensioning devices of this kind are made by simply screwing two flat-edged housing pieces together. Dirt, debris and moisture may easily penetrate this type of joint and cause damage to the mechanisms inside the housing. Additionally, the use of actuating levers creates an easy path for dirt, debris and moisture to enter and damage the device. It is also noted that the tensioning cord is generally equipped with crimped on or cast on ends and that one of these ends is then passed through a grommet and that the grommet and the cord are then incorporated into the tensioning device during assembly. In order to accept the crimped or cast on end, the opening in the grommet is required to be quite a bit larger than the diameter of the cord and the difference in size provides another area where an easy path is provided for dirt, debris and moisture to enter and damage the device. 
     SUMMARY OF THE INVENTION 
     The present invention provides a self-tensioning snow chain for attachment to a wheel of a vehicle, the self-tensioning snow chain includes a snow chain; and a tensioning device. The tensioning device includes (1) a housing having a top including a set of housing teeth, a bottom and at least one aperture defined by the top and the bottom when joined together; (2) a lever interconnected to the housing; (3) a cord; (4) a ratchet spool having a set of ratchet teeth on an upper surface, the ratchet teeth constructed and arranged to mate with the housing teeth, an under surface and a channel between the upper surface and the under surface in which sufficient space is provided to receive the cord, wherein the cord is interconnected with the ratchet spool; (5) a tension spring interconnected with the ratchet spool and constructed and arranged to place a bias on the ratchet spool toward a wind-up direction; and (6) a wave spring positioned between a top surface of the bottom of the housing and the under surface of the ratchet spool to bias the ratchet spool in the direction of the housing teeth; wherein the snow chain is interconnected with the tensioning device and the cord can be connected with the snow chain so that the tensioning device can secure the snow chain to the wheel. The snow chain can also be a traction cable or the like that is made out of rope, wire, wire rope, chains and the like. 
     It is an object of the present invention to provide a self-tightening snow chain that more effectively tightens and is easier to install. It is another object of the present invention to provide a self-tightening snow chain that may tighten a plurality of cords with one winding device, preferably a ratchet spool. It is yet another object of the present invention to provide a self-tightening snow chain having a tensioning device that is resistant to an infiltration of dirt, debris and moisture into the housing. 
     The present invention achieves these and other objectives by providing a self-tightening snow chain having two modes of operation. First, is an extended or extending mode that allows the user to extend the cord from the housing and release their grip on the cord without having the cord wind-up into the housing. The ability to only allow movement in a wind-out direction is created when the ratchet spool is in down position, where the spool, although biased in a wind-up direction, is blocked from turning in a wind-up direction. To get the ratchet spool in the down position, the user raises the actuating lever until it is perpendicular to the housing. This action forces a cam-lever to push the ratchet spool down. When the ratchet spool is in the down position, the ratchet teeth are disengaged from the housing teeth thereby allowing movement of the ratchet spool in either direction. However, movement in the wind-up direction is prevented by catches on the under surface of a ratchet spool that are pushed into a zone of a stop or stopper where they will be blocked by the stopper, thereby stopping the ratchet spool from turning in a wind-up direction more than a full turn, a half turn or preferably a quarter turn. When the user wants to continue extending the cord, the cord simply needs to be pulled further outward. 
     Second, is a self-tightening mode wherein the cord may only move in the wind-up direction. This mode is for when the cord is engaged and in use and the user wants to maintain constant tension on the snow chain without the possibility of the cord extending out. To operate in this mode, the user lowers the actuating lever until it snaps back into a position adjacent to the housing. When the actuating lever is down, the ratchet spool is up. Therefore, the housing teeth and the ratchet teeth are engaged to only allow movement in the wind-up direction. When the ratchet spool is in the up position, the catches cannot be blocked by the stopper, which would otherwise prevent more than a small movement of the ratchet spool in the wind-up direction. 
     In an alternate embodiments of the present invention, the ratchet and housing teeth may be overcut or undercut. In preferred embodiments, the respective teeth will be undercut at an angle ranging from about 3 to about 30 degrees, preferably about 5 to about 25 degrees more than the 90 degree angle to a horizontal plane b perpendicular to a vertical axis c of the ratchet spool and the housing. In the most preferred embodiment, the respective teeth will be undercut about 20 degrees more than the 90 degree angle to a horizontal plane b perpendicular to a vertical axis c of the ratchet spool and the housing. Therefore, when the teeth are undercut, and the device is in a wind-up mode and the cord is tugged outwardly, the harder the cord is tugged, the more the ratchet teeth will become engaged and resist the cord being moved in the wind-out direction. This is particularly important during normal conditions, when a significant amount of vibration results from interaction between the tire and the road surface. 
     In another embodiment of the tensioning device of the present invention, a plurality of cords, all interconnected with the same winding device or ratchet spool, may extend from different apertures or openings of the housing. Although it is possible to have more than three cords extend from a single tensioning device, such a device may be difficult to optimize because of the limited room on the ratchet spool, unequal forces that could be placed on each cord when in use and also the potential need for a tension spring that can generate greater winding force on the spool that may be needed to wind a greater number of cords. 
     Additionally, a lip and groove configuration may be utilized to aid in sealing the housing from dirt, debris and moisture. For example, a lip may trace along the opening of the housing top and a groove may trace along the opening of the housing bottom. When the two housing components are joined together, the lip and groove will mate to form a more secure seal than if two flat surfaces are pressed together. Alternatively, the lip may trace along the opening of the housing bottom and the groove may trace along the opening of the housing top. 
     To further protect the internal components, a grommet having an opening only slightly larger than the diameter of the cord may be utilized. If the grommet is secured around the cord prior to securing knobs at both ends of the cord, the grommet opening can be smaller than the diameter of the knobs, thereby reducing the size of the passageway in the grommet where dirt, debris and moisture can breach the housing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings, in which corresponding reference numerals and letters indicate corresponding parts of the various embodiments throughout the several views, and in which the various embodiments generally differ only in the manner described and/or shown, but otherwise include corresponding parts; 
         FIG. 1  is a perspective view of one embodiment of a self-tightening snow chain  10  of the present invention having a tensioning device  11 , wherein the self-tightening snow chain is in use attached to a wheel  16  (partially shown); 
         FIG. 2  is a perspective view of the tensioning device  11  of  FIG. 1 ; 
         FIG. 3  is an exploded perspective view of the tensioning device  11  of  FIGS. 1-2 ; 
         FIG. 4  is an exploded, partial, schematic view of certain components of the tensioning device  11  of  FIGS. 1-3  illustrating the location of the ratchet spool  100 , a compression spring  106  and a stopper  108  within a housing bottom  12 b of the tensioning device; 
         FIG. 5  is a partial perspective view of the stopper  108  and compression spring  106  of  FIG. 4  fitted in the housing bottom  12 b of the tensioning device  11  of  FIG. 4 ; 
         FIG. 6  is a partial perspective view of a portion of the housing of the tensioning device of  FIGS. 1-5  illustrating elements  40 ,  42  of a housing lip and groove joint; 
         FIG. 7A  is a perspective view of a tensioning cord sub-unit  134  of the tensioning device  11  of  FIGS. 1-6  and showing the hook  18 , to which the connector  22  is secured, in phantom; 
         FIG. 7B  is a perspective view of components of the tensioning cord sub-unit  134  shown in  FIG. 7A , before it is completely assembled; 
         FIG. 8A  is a partial, schematic view of the tensioning device  11  of  FIG. 1  showing the internal components when the lever  26  is in a down or disengaged position and the ratchet spool  100  is in an up or engaged position within the housing, which is shown in phantom, but without showing the wave spring(s) to permit clarity; 
         FIG. 8B  is a partial, schematic view of the tensioning device  11  shown in  FIG. 1 , similar to that shown in  FIG. 8A , but showing the tensioning device  11  when the lever  26  is in an up position and the ratchet spool  100  is in a down position; 
         FIG. 9A  is an enlarged, partial, schematic view of a portion of tensioning device  11  shown in area  9 a- 9 a of  FIG. 8B  illustrating the ratchet teeth  102  and housing teeth  118  cut at an angle “a” of about 90 degrees to a horizontal plane “b” perpendicular to a vertical axis “c” of the ratchet spool and the housing; 
         FIG. 9B  is an enlarged, partial, schematic view similar to that shown in  FIG. 9A , but illustrating a preferred embodiment, wherein the ratchet and housing teeth  102 ,  118  are undercut about 20 degrees more than a 90 degree angle to a horizontal plane “b” perpendicular to a vertical axis “c” of the ratchet spool and the housing; 
         FIG. 10A  is a diagrammatic view of the positioning of the tensioning devices  11  of the present invention showing a preferred positioning on a wheel  16  (shown in phantom) of two, single-cord tensioning devices  11  similar to the one shown in  FIG. 1 ; 
         FIG. 10B  is a diagrammatic view of the positioning of an alternate tensioning device  11 ′ of the present invention showing a preferred positioning of a single, dual cord tensioning device  11 ′ that tightens two tensioning cords  20  with respect to a snow cable (not shown) on a wheel  16  (shown in phantom); 
         FIG. 10C  is a diagrammatic view of the positioning of an alternate tensioning device  11 ″ of the present invention showing a preferred positioning of a single, multiple cord tensioning device  11 ″ that tightens three tensioning cords  20  with respect to a snow cable (not shown) on a wheel  16  (shown in phantom); 
         FIG. 11A  is a plan view of a dual cord tensioning device  11 ′, similar to the tensioning device  11  shown in  FIG. 1 , but where the tensioning device  11 ′ includes two cords  20 a,  20 b; 
         FIG. 11B  is a plan view of a triple cord tensioning device  11 ″, similar to the tensioning device  11  shown in  FIG. 1 , but where the tensioning device  11 ″ includes three cords  20 a,  20 b,  20 c; 
         FIG. 12A  is a perspective view of a ratchet spool  100 ′, similar to that shown in  FIG. 3 , but for a dual cord tensioning device  11 ′ of the present invention, wherein two tensioning cords  20 a,  20 b are wrapped around a single ratchet spool  100 ; when the cords are fully wound in; 
         FIG. 12B  is a perspective view of a ratchet spool  100 ″ for a triple cord tensioning device  100 ″ of the present invention wherein three tensioning cords  20 a,  20 b,  20 c are wrapped around a single ratchet spool  100 ″ when the cords are fully wound in; 
         FIG. 13  is a perspective view of the housing  12 ′″ of an alternate embodiment of a single cord tensioning device; wherein buttons  136 b are used to actuate or change tensioning device modes; 
         FIG. 14  is an exploded view of an alternate single cord tensioning device  11 ′″ having a housing  12 ′″ like that shown in  FIG. 13 , but not including a tensioning cord sub-unit; 
         FIG. 15  is a diagrammatic view of the tensioning device  11 ′″ of  FIGS. 13 and 14 , showing the pivot and contact points of the pawls  152  and top button  138 ; 
         FIG. 16A  is a sectional view, similar to that shown in  FIG. 8A , but showing the alternate tensioning device  11 ′″ of  FIG. 13 , showing the internal components when the top button  138  is in the up position and the ratchet spool  100  is in the up position (wave spring(s) not shown for clarity); and 
         FIG. 16B  is a sectional view, similar to that shown in  FIG. 8B , but showing the alternate tensioning device  11 ′″ of  FIG. 13 , showing the internal components when the top button  138  is in the down position and the ratchet spool  100  is in the down position (wave spring(s) not shown for clarity). 
       Preferred embodiments of the present invention are illustrated in  FIGS. 1-16B .  FIG. 1  is a perspective view of a self-tightening snow chain  10  of the present invention in use on a wheel  16  (partially shown). The self-tightening snow chain  10  comprises of a snow chain  14  and a tensioning device  11 . Referring now also to  FIGS. 2 and 3 , the tensioning device  11  has a housing  12  including a housing top  12 a, an actuating lever  26 , a grommet  32 , and a cord  20  extending through grommet  32  and connected to a hook  18  with a first connection member  22 . The hook  18  connects to the chain  14  of the self-tightening snow chain  10 , to supply tension to the chain  14 . In this embodiment, there is a second connection point  24  and third connection point  30  where parts of the snow chain  14  are secured to the housing  12 . Rivets  28  are placed through rivet receiving openings or recesses  29  to secure the housing top  12 a to the housing bottom  12 b, although any other fasteners such as threaded screws, bolts and nuts, adhesives, double backed tape and the like could be used. The housing top  12 a has a recess  34  to prevent distortion during injection molding, which may additionally be used as a place for company identifiers and the like, if desired. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Preferred embodiments of the present invention are illustrated in  FIGS. 1-16B   FIG. 1  is a perspective view of a self-tightening snow chain  10  of the present invention in use on a wheel  16  (partially shown). The self-tightening snow chain  10  comprises of a snow chain  14  and a tensioning device  11 . Referring now also to  FIGS. 2 and 3 , the self-tightening snow chain  10  has a housing  12  including a housing top  12 a, an actuating lever  26 , a grommet  32 , and a cord  20  extending through grommet  32  and connected to a hook  18  with a first connection member  22 . The hook  18  connects to the chain  14  of the self-tightening snow chain  10 , to supply tension to the chain  14 . In this embodiment, there is a second connection point  24  and third connection point  30  where parts of the snow chain  14  are secured to the housing  12 . Rivets  28  are placed through rivet receiving openings or recesses  29  to secure the housing top  12 a to the housing bottom  12 b, although any other fasteners such as threaded screws, bolts and nuts, adhesives, double backed tape and the like could be used. The housing top  12 a has a recess  34  to prevent distortion during injection molding, which may additionally be used as a place for company identifiers and the like, if desired. 
       FIG. 2  is a perspective view of the housing  12  of the tensioning device  11  shown in  FIG. 1 . The housing top  12 a can be secured to the housing bottom  12 b by rivets or threaded screws (not shown) that may inserted through the holes  29 . The housing top  12 a and the housing bottom  12 b define an aperture  38  for receiving the grommet  32  that provides a passageway for the tensioning cord  20 . Additionally, an actuating lever  26  including a cam  126  is pivotally connected to the housing top  12 a. 
     In  FIG. 3 , there is illustrated an exploded view of one embodiment of the tensioning device  11  of the present invention. A wave spring  112  sits on the inside of the housing bottom  12 b. The wave spring  112  is positioned in a way to apply pressure to the ratchet spool  100 . The tension spring  110  also rests inside the ratchet spool  100  and has a crimp  122  that mates with a notch  120  in the ratchet spool  100  to secure the tension spring  110  to the ratchet spool  100 . The ratchet spool  100  has a center channel  124  running circumferentially around its exterior and is sufficiently wide and deep enough for a cord  20  to be wound within the channel  124  around the ratchet spool  100 . In this embodiment, the under surface  132  of the ratchet spool  100  has four catches  104 . It is not essential that there be four catches  104  as two to six catches  104  will result in similar function. More than six catches  104  is possible but not recommended. As better shown in  FIGS. 8A-8B , the catches  104  prevent the ratchet spool  100  from rotating in the wind-up direction when they are blocked by the stopper  108 . The catches  104  can only be blocked by the stopper  108  when the ratchet spool  100  is in the down position (when the cam  126  is in the down position/the actuating lever  26  is in the up position). On the top of the ratchet spool  100  are ratchet teeth  102 . As seen in  FIGS. 8A and 8B , the ratchet teeth  102  can engage with the housing teeth  118  located in the housing top  12 a when the actuating lever  26  is oriented in the down position. When the actuating lever  26  is in the down position, a cam  126 , which extends from the actuating lever  26 , is parallel to the plane of rotation of the ratchet spool  100 . Therefore, there is no added pressure on the wave spring  112 , which allows the wave spring  112  to push the ratchet spool  100  to its up position, engaging the ratchet spool  100  with the housing teeth  118 . When the actuating lever  26  is in the up position/the cam  126  is in a down position and pushes the top base  114  down against the ratchet teeth  102 , which are subsequently pushed down thereby disengaging the ratchet teeth  102  from the housing teeth  118 . The top  116  has slots  117  for the cam levers  26  to rotate. The housing teeth  118  are molded into the housing top  12 a. 
     The stopper  108  has an up position and a down position. Referring now also to  FIGS. 4 and 5 , showing the arrangement of the catches  104 , the compression spring  106  and stopper  108  in the up position. The compression spring  106  is attached to the stopper  108  and they both are placed in the housing bottom  12 b such that the compression spring  106  applies force to the housing bottom  12 b. The compression spring  106  places a bias on the stopper  108  such that the stopper  108  will block a catch  104  should the ratchet spool  100  be in the down position and rotating in the wind-up direction so that the ratchet spool will not rotate more than 360 degrees in the wind-up direction when the ratchet spool  100  is in a down position. One preferred tensioning device  10  includes a housing  12  having a stop and a set of housing teeth; a winding mechanism including a spool  100  having set of ratchet teeth  102  and at least one catch  104 , the winding mechanism located within the housing  12 ; and a cord  20  operatively connected to the spool  100 ; wherein the winding mechanism has two positions that control the movement of the cord  20 , the first position being a wind-up position where the cord is pulled into the housing and cannot be pulled outwardly from the housing, the second position being a wind-out position wherein the cord may be pulled outwardly from the housing. In this preferred embodiment, if the cord  20  is pulled outwardly from the housing  12  and then released, while the winding mechanism is in the second position, the cord will retract into the housing until the catch  104  contacts the stop or stopper  108  such that the spool  100  will rotate less than 360 degrees before the catch contacts the stop and the stop is spring biased such that the stop will block one of the at least one catches when the ratchet teeth are disengaged with the housing teeth and the spool is rotating in a wind-up direction. 
     Now also referring to  FIG. 6  showing the lip  40  and groove  42  configuration near the aperture  38  defined by the housing  12 . The lip  40  and groove  42  mate to form a housing joint  44  resistant to dirt, debris and moisture. The present invention further includes a method of attaching two housing pieces of a tensioning device for use with a self-tensioning snow chain, wherein the method comprises the steps of providing a first and second housing piece  12 a,  12 b. One respective housing piece  12 b has a lip  40  and the other respective housing piece  12 a has a groove  42  such that the lip can be mated with the groove within a joint between the top and the bottom  12 a,  12 b of the housing  12 . 
     Now also referring to  FIGS. 7A and 7B  showing an assembled tensioning cord sub-unit  134 . A cord  20  is threaded through a grommet  32  and has a first knob  128 a and a second knob  128 b. The knobs  128  may be fitted to the cord  20  by crimping, melting, casting and the like. The cord  20  is threaded through the grommet  32  before both of the knobs  128  are fitted to the cord  20 , which permits the diameter of the grommet  32  to be smaller than the diameter of the knobs  128 , so that the grommet  32  may more closely fit the cord  20 , allowing the grommet to be more appropriately sized to limit the infiltration of dirt, debris and moisture into the housing  12 . The cord  20  is attached to the first connection member  22  that is connected to a hook  18  (shown in phantom) used for securing the tensioning device  11  to parts of the snow chain  14 .  FIG. 7B  shows how the second knob  128 b fits into a recess  46  (partially shown) formed by a first piece  22 a and second piece  22 b of the first connection member  22 . The first and second pieces  22 a and  22 b are secured together around the second knob  128 b that is tightly secured to the cord  20 . Rivets  23  are placed through rivet receiving openings  25  to secure first and second pieces  22 a and  22 b together, although any other fasteners such as threaded screws, bolts and nuts, adhesives, double backed tape and the like could be used. 
     Referring now also to  FIGS. 8A and 8B ,  FIG. 8A  is a sectional view showing the internal components when the actuating lever  26  is in the down position thereby allowing the ratchet spool  100  to be in the up position. When the ratchet spool  100  is in the up position, the catches  104  are clear of the stopper  108  thereby allowing the ratchet spool  100  to freely wind-up and tighten the cord  20 . In this mode, the ratchet spool  100  may only rotate in the wind-up direction, because the ratchet teeth  102  can fully engaged with the housing teeth  118  to limit rotation if an extending or wind-out force is applied to the cord  20 . 
       FIG. 8B  is a sectional view showing the internal components when the actuating lever  26  is in the up position thereby forcing the ratchet spool  100  to be in the down position. While the ratchet spool  100  is in the down position, the ratchet teeth  102  are disengaged from the housing teeth  118 . This allows the ratchet spool  100  to rotate freely in either direction. The catches  104  stop the ratchet spool  100  from fully rotating in the wind-up direction. As the ratchet spool  100  begins to rotate in the wind-up direction, the stopper  108  will block the next catch  104  it encounters, thereby preventing the ratchet spool  100  from further winding-up. 
     In the embodiment shown in  FIGS. 8A through 9A , the ratchet teeth  102  and the housing teeth  118  are cut at an angle “a” of about 90 degrees to a horizontal plane perpendicular to a vertical axis of the ratchet spool and the housing. In alternate embodiments of the present invention, the ratchet teeth  102  and housing teeth  118  may be overcut or undercut. The teeth  102 , 118  may be undercut at an angle ranging from about 3 to about 30 degrees, preferably from about 10 to about 25 degrees more than a 90 degree angle to a horizontal plane b perpendicular to a vertical axis c of the ratchet spool and the housing, so that when the tensioning device  11  is in a wind-up mode and the cord is tugged outwardly, the more the ratchet teeth  118  will become engaged and resist the cord  20  being moved in the wind-out direction. In the most preferred embodiments, the teeth  102 ,  118  are undercut at an angle a′ of about 20 degrees more than a 90 degree angle to a horizontal plane b perpendicular to a vertical axis c of the ratchet spool and the housing, as illustrated in  FIG. 9B . 
     Now referring also to  FIG. 10A ,  FIG. 10A  is a diagrammatic view of one embodiment of the present invention showing the preferred positioning of two, single tensioning devices  11  attached to a wheel  16 . In this embodiment, the tensioning devices  11  are approximately 180 degrees from each other and their respective cords  20  and hooks  18  extend in opposite directions. 
     Referring now also to  FIGS. 10B and 10C ,  FIG. 10B  is a diagrammatic view of one embodiment of the present invention showing the preferred positioning of a single, tensioning device  11 ′ attached to a first cord  20  and a second cord  20 a that each have their respective hooks  18 . In this embodiment, the tensioning device  11 ′ is centered with the exterior of the wheel  16  to provide equal tension on the first cord  20 a and the second cord  20 b which extend parallel to each other. 
       FIG. 10C  is a diagrammatic view of one embodiment of the present invention showing the preferred positioning of a single, tensioning device  11 ″ attached to a first cord  20 , a second cord  20 b, and a third cord  20 c that each have their respective hooks  18 . The tensioning device  11 ″ is centered with the exterior of the wheel  16  to provide equal tension on the first cord  20 a, the second cord  20 b, and the third cord  20 c, which extend approximately 120 degrees from each other. 
     Now referring also to  FIG. 11A  that shows another embodiment of the tensioning device of the present invention wherein the tensioning device  11 ′ tensions a first cord  20 a and a second cord  20 b. Referring now also to  FIG. 11B , which shows another embodiment of the tensioning device  11 ′ of the present invention, wherein the tensioning device  11 ″ applies tension to a first cord  20 a, a second cord  20 b and a third cord  20 c. 
     Now referring also to  FIG. 12A ,  FIG. 12A  is a perspective view of one embodiment an alternate ratchet spool  100 ′ of the present invention showing the ratchet spool  100 ′ configuration of having a first cord  20 a and a second cord  20 b that are attached to the ratchet spool  100 ′ and wound in the channel  124 . In this embodiment, only two catches  104  are on the under surface  132  of the ratchet spool  100 ′, because less space is available. The first cord  20 a and second cord  20 b have a first knob  128 a fitted to their respective ends sized to fit snuggly into the ratchet spool recess  130  to prevent the first cord  20 a and the second cord  20 b from being pulled off of the ratchet spool  100 ′. 
     Referring now also to  FIG. 12B ,  FIG. 12B  shows a perspective view of an embodiment of the present invention showing a further alternate ratchet spool  100 ″ configuration having a first cord  20 a, a second cord  20 b, and a third cord  20 c. 
     Referring now to  FIGS. 13-16B , there is illustrated an alternate tensioning device  11 ′″ having a housing  12 ′″ having a housing top  12 a′″ and a housing bottom  12 b′″. There are holes  29  where rivets (not shown) will be inserted to attach the housing top  12 a′″ and the housing bottom  12 ′″ as in the other embodiments of the tensioning device. Located on the housing top  12 a′″ is a top button  138 . Additionally, on the side of the housing  12 ′″ are a first side button  136 a and a second mirroring side button  136 b (not shown). Protruding from the housing  12 ′″ is a grommet  32  from which a cord  20  (not shown) may pass. 
       FIG. 14  shows an exploded view of the tensioning device  11 ′″ shown in  FIG. 13 , but without the tensioning cord sub-unit  134 . A wave spring  112  sits on the inside of the housing bottom  12 b′″ and is positioned in a way to apply pressure to the ratchet spool  100 . A washer  156  is placed in between the wave spring  112  and the ratchet spool  100 . The tension spring  110  also rests inside the ratchet spool  100  and has a crimp  122  that can be inserted into a notch  120  (not shown) in the ratchet spool  100 , similar to that shown in  FIG. 3 , to secure the tension spring  110  to the ratchet spool  100 . The ratchet spool  100  has a channel  124  running around the outside of the ratchet spool  100  in the center and is sufficiently wide and deep enough for a cord  20  (not shown) to be wound around the rachet spool  100  within the channel  124 . On the top of the ratchet spool  100  are ratchet teeth  102 . The ratchet teeth  102  engage with the housing teeth  118  (not shown). In addition, there is a pawl  152 , connected to each of the side buttons  136 , having a pivot point  150 . The side buttons  136  are spring loaded with a pawl spring  154 . As seen in  FIGS. 16A and 16B , the ratchet teeth  102  engage with the housing teeth  118  (not shown) located in the housing top  12 a′″ when the top button  138  is in the up position. When the top button  138  is in the up position, the ratchet spool  100  can only move in the wind-in direction to tighten the cord  20  (not shown). In this mode, the side buttons  136  are pushed into the housing  12 ′″. When the top button  138  is in the down position, the ratchet spool  100  may move in either the wind-in or the wind-out direction. In this mode, the side buttons  136  are pushed out of the housing  12 ′″ by the force of the spring  154 . 
     Referring now also to  FIG. 15 , showing the positioning of the top button  138  and the side buttons  136  when the top button  138  is in the up position. Here, the side buttons  136  are pushed into the housing  12 ′″. Two button springs  154  rest against the interior of the housing top  12 a′″ and apply pressure to move the side buttons  136  out of the housing  12 ′″. However, the side buttons  136  do not move out of the housing because the pawls  152  are stopped by the top button  138 . When the top button  138  is pushed down, the pawls  152  are no longer blocked and the side buttons  136  will pop out of the housing  12 ′″. When housing teeth  118  are not in contact with the ratchet teeth  102  (not shown), the ratchet spool  100  (not shown) can rotate freely. 
     Referring now also to  FIGS. 16A and 16B ,  FIG. 16A , shows the arrangement of the side buttons  136 , the top button  138 , the ratchet teeth  102 , and the housing teeth  118  when the top button  138  is in the up position. When the top button  152  is in the up position, the pawls  152  engage with the ratchet teeth  102  and the ratchet spool  100  can only move in the wind-up direction. In this view, for clarity, the wave spring  112  is not shown. 
     Referring now also to  FIG. 16B , illustrating the arrangement of the top button  152 , the ratchet teeth  102 , and the housing teeth  118  when the top button  138  is in the down position. As the top button  138  gets pushed into to the down position, the force created by the button springs  154  (see  FIGS. 14 and 15 ) snaps the pawls  152  away from the ratchet teeth  118  so that the ratchet spool  100  can move in the wind-in or wind-out direction. To switch modes and prevent the ratchet spool  100  from rotating in the wind-out direction, the user presses the side buttons  136  back into the housing  12 ′″ to force the top button  138  back up and allow the pawls  152  to again come into contact with the ratchet teeth  118 . In this view, for clarity, the wave spring  112  is not shown. 
     Although the preferred embodiments of the present invention have been described herein, the above description is merely illustrative. Further modification of the invention herein disclosed will occur to those skilled in the respective arts and all such modifications are deemed to be within the scope of the invention as defined by the appended claims.