Abstract:
The invention is a method and apparatus for correcting the natural nock travel of a compound bow. The bow has a cable guard rod attached to a riser supporting a cable slide at an angle to the nock travel path. The rod has a distal portion attached to the riser, a central portion angled upward relative to the distal portion, and, a proximal portion angled downward so as to form an exterior angle falling within the range of 25-40° between the proximal and distal portions of the cable guard rod. The bow has a cam mounted on an upper limb, a cam mounted on a lower limb, and two cables which are connected to the first cam, pass through the cable slide, and are connected to the second cam. There is also a bow string connected between the cams which can be drawn rearward then released to provide energy.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a method and apparatus for a compound archery bow of a type used for hunting, target shooting, or related activities. More specifically, the present invention relates to a method and system for stabilizing the nock point travel of a compound bow so as to optimize the bow&#39;s accuracy while reducing wear on cables caused by cam tilt forces. 
         [0003]    2. Description of the Related Art 
         [0004]    Compound archery bows, such as that shown in  FIG. 1 , generally provide a number of benefits over traditional bows (also known as long bows). They store a lot more energy due to the profiles of the cams which flex the limbs while the bow is drawn. This results in an arrow that is shot with higher velocity and more energy. They also provide another important benefit over traditional bows, in that when the bow is drawn to its maximum point, the cams provide a mechanical advantage to the archer that reduces the holding weight of the bow by approximately 75-80%. 
         [0005]    A traditional bow has a bow string, a handle and an upper and a lower limb. One end of a bowstring is attached to the upper limb of the bow while the other end of the string is attached to the lower limb. With a typical compound bow, however, as is shown in  FIG. 1 , the bow has a bow string  8 , a handle  40 , two limbs  46   a,    46   b,  plus one or two cables  4 ,  6  which are fastened to the cam or cams  30   a,    30   b  or limb(s)  46   a,    46   b,  plus a cable guard rod  10  and cable slide  2  or, in an alternative, a roller cable guard  18  (as is shown in  FIG. 3 ). 
         [0006]    The cables  4 ,  6  are in the path of the arrow  14  (as is shown in  FIG. 4 ) and its fletching when shot, and must be offset  20  (see  FIG. 4 ) from the line of arrow travel to prevent collision of the arrow  14  and its fletching  12  into the cables  4 ,  6 . The cams  30   a,    30   b  should be designed in such a way as to provide an arrow launch that is as straight as possible, both vertical and horizontally. 
         [0007]    Turning to  FIG. 6 , there is shown a top view of the nocking point travel of the typical compound bow. Accuracy may be degraded by an arrow launch that is not straight and/or has a vertical path that deviates from a reference plane that is perpendicular to the string. Lateral motion is defined by deviation from a plane that is perpendicular to the limbs  46   a,    46   b  (see  FIG. 1 ) or its “natural travel path”  28  (see  FIG. 12A ). Deviation from the natural travel path degrades accuracy. 
         [0008]    The natural travel path  28  is always negatively affected by offsetting the cables  4 ,  6 . Virtually all compound bows made today have a cable guard  10  (see  FIG. 1 ) in one form or another, and they offset the cables  4 ,  6  to provide clearance for the arrow and its fletching. This is required when the arrow is launched/shot. Typically, the bow&#39;s cables are confined within a cable slide  2  that mounts on a cable guard rod  10  which is mounted in the riser  16 ; or, a roller cable guard  18  (see  FIG. 3 ) which is mounted on the riser  16 . 
         [0009]    Turning to  FIG. 3 , there is shown an enlargement of the end view of a prior art compound bow. The cables are held offset  20  through the entire draw cycle. 
         [0010]    Some bows (such as that shown in  FIG. 3 ) use a fixed set of rollers  18  to confine the cables  4 ,  6  to achieve the required fletching clearance  20 . The rollers are generally fixed to bracket  22  that is fastened to the bow&#39;s riser  16 . The cables are held offset to provide fletching clearance  20  through the entire draw cycle. 
         [0011]    It is not generally understood what affect a cable guard and the resulting cable offset has on the flight of the arrow, the nocking point, bow string travel, and the resulting arrow flight aberration as is illustrated in  FIG. 5 . Additionally, the twisting of the bow handle  40  in the archer&#39;s hand  42  also produces flight aberration that is unique to the archer (see  FIG. 7 ). 
         [0012]    The string travel when measured at the arrow nocking point  26  located on the bow string  8  with absolute minimum cable guard offset follows a path that is essentially straight and perpendicular to the bow&#39;s limbs as they are flexed—its “natural travel path”. 
         [0013]    Turning next to  FIG. 5 , there is shown a side view of the cam tilting forces at play during the typical draw cycle of a compound bow. The addition of a cable guard  10  and the cable offset  20  imposes a side load  48  on the bow&#39;s cam(s)  30   a,    30   b  which causes a tilt  32  and a change in position of the bow string with respect to its natural travel path. The tilting  32  increases as the bow is drawn and reaches its peak draw weight (see  FIG. 11A ). This effect imposes much higher loads on the cam axles  34   a,    34   b;  and, therefore, the cams  30   a,    30   b  by the flexure of the limbs  46  which increases dramatically as the bow is drawn. During this latter action, the loads can be as high as 400 lbs. These high loads imposed off center on the cams create a very large load imbalance (see  FIG. 11A ) which causes the cam(s) to tilt. The cam(s) radius (see  FIGS. 11A and 11B ) also increases through the draw cycle and moves the string farther from the cam(s) center line producing a mechanical advantage for the archer drawing the bow; but, causing even more cam tilting and lateral displacement of the bow string. 
         [0014]    The combined effect of the cable guard offset and increasing cable loads results in a cam tilt that produces an angular lateral displacement of the bow string during the bow&#39;s draw cycle. It causes the bow to twist in the archer&#39;s hand and results in undesirable “angular nocking point/bow string travel”. 
         [0015]    As is shown in  FIG. 6 , the bow string lateral displacement causes the arrow to be launched at an angle  50  which may be as high as 5 degrees with regard to the bow string&#39;s natural string travel  28 . When the arrow is shot, the bow string and nocking point does not align to the natural string travel  13 . During launch, the arrow has an acceleration force imposed upon it that is not aligned with the arrow centerline and its natural string travel, this creates a side acceleration force  36  on the arrow which is essentially 90 degrees to the arrow&#39;s center line. This can result in arrow flight that slews back and forth, commonly known as “fishtailing”. 
         [0016]    Turning to  FIG. 7 , there is shown a top view of the handle torque effect of a compound bow. The “angular nocking point/bow string travel”  24  also results in a rotation or twisting of the bow in the archer&#39;s hand  42 . It is commonly referred to as “torque”. Although only a few degrees in bow rotation, torque is undesirable as it causes the arrow to fly to left for right handed archers, and to the right for left handed archers. This is detrimental to the archer achieving accurate and consistent arrow flight. The archer will have to try and compensate for this cable guard induced error, “angular nocking point/bow string travel”  50 . 
         [0017]    The stock or existing angular nocking point/bow string travel  50 , the natural travel path  28 , and the optimized nocking point/string travel may be accurately verified by plotting their travel on a lateral nock travel testing fixture. The optimized nocking point and string travel will closely parallel the natural travel path. 
         [0018]    What is not appreciated by the prior art are problems created by the cables being offset to provide fletching clearance, the unintended consequence of which is cam tilt. Therefore, an ideal condition would be to provide fletching clearance as the arrow&#39;s fletching approaches the cables, and quickly reduce the cable offset during the rest of the shot. This will result in a nocking point travel that closely follows the natural string travel path  28  by virtually eliminating cam tilt. 
         [0019]    Accordingly, there is a need for an improved method and apparatus for providing fletching clearance as the arrow&#39;s fletching approaches the cables, and quickly reducing the cable offset during the rest of the shot. This will result in a nocking point travel that closely follows the natural string travel path  28  by virtually eliminating cam tilt. The result of an optimized nocking point/string travel which closely follows the natural string path  28  also results in almost zero handle rotation and twisting of the bow in the archer&#39;s hand  42 . The bow that is without torque/handle rotation will result in a bow with more accuracy and repeatability in discharging the arrow and is considered to be “forgiving”. 
         [0020]    Additionally, there is a need for a method and apparatus that optimizes arrow nocking point/bow string travel by closely following the natural string path, which is essentially straight with no side acceleration forces. This condition will impart the least possible lateral flight aberration. 
       OBJECTS AND SUMMARY OF TH INVENTION 
       [0021]    An object of the present invention is to provide an improved method and apparatus for providing fletching clearance as the arrow&#39;s fletching approaches the cables, and quickly reducing the cable offset during the rest of the shot. 
         [0022]    Another object of the present invention is to provide a method and apparatus that optimizes arrow nocking point/bow string travel by closely following the natural string path, which is essentially straight with no side acceleration forces. 
         [0023]    The present invention relates to a method and apparatus for correcting the angular nock travel of a compound bow. The bow has a cable guard rod attached to a riser supporting a cable slide at an angle to the nock travel path. The rod has a distal portion attached to the riser, a central portion angled upward relative to the distal portion, and, a proximal portion angled downward so as to form an exterior angle falling within the range of 25-40° between the proximal and distal portions of the cable guard rod. The bow has a cam mounted on an upper limb, a cam mounted on a lower limb, and two cables which are connected to the first cam, pass through the cable slide, and are connected to the second cam. There is also a bow string connected between the cams which can be drawn rearward then released to provide energy. 
         [0024]    According to an embodiment of the present invention, there is provided a method and apparatus for a compound archery bow of a type used for hunting, target shooting, or similar endeavor. The compound bow has a handle and a riser, and at least an upper and a lower limb. A cable guard rod is attached to the riser; and is made in such a way as to support a cable slide at an angle to the nock travel path of the compound bow. The cable slide is slidably mounted on the cable guard rod. 
         [0025]    Additionally, the compound bow has a first cam, having a first cam axle, mounted on the upper limb; and, a second cam, having a second cam axle, is mounted on the bow&#39;s lower limb. The bow also has a first cable and a second cable, wherein the first and second cables are connected to the first cam (or a wheel), pass through the cable slide, and are connected to the second cam (or a wheel). There is also a bow string connected at one end to the first cam and at another end to the second cam. 
         [0026]    In an embodiment of the present invention, the bow&#39;s cable guard rod is attached to the riser by securably inserting the rod within a supporting block and mounting the supporting block on the riser. In an alternative embodiment of the present invention, the distal end of the cable guard rod is attached to directly to the riser by inserting the distal end within an opening of the riser. The cable guard rod, at least at the distal end, is substantially perpendicular to the riser. 
         [0027]    The cable guard rod can be made of any material suitable to the purpose such as aluminum, steel, or a composite capable of maintaining rigidity while under pressure from the forces exerted on the compound bow during operation. 
         [0028]    The cable guard rod can be manufactured as a single piece or as two or more pieces and wherein the pieces are joined by any means such as welding, screw and bolt combination, or similar process so as to maintain performance of the cable guard rod. 
         [0029]    The cable guard rod is fashioned so as to comprise three portions; these include: a distal portion attached either directly, or indirectly, to the riser and essentially perpendicular to the riser; a central portion attached to the distal portion and angled upward relative to the distal portion; and, a proximal portion attached to said central portion and angled downward so as to form an exterior angle falling within the range of 25-40° between the proximal and distal portions of the cable guard rod. 
         [0030]    The cable guard slide is mounted on the cable guard rod so as to accept the first cable and the second cable passing therethrough. The forward or rearward motion of the first and second cables causes the cable guard slide to slidably move along the cable guard rod in an angled path relative to the nock travel path. 
         [0031]    As the bowstring is drawn rearward by a bow user during operation, the top and bottom limbs of the compound bow flex rearward causing the cam(s) to rotate, thus shifting the first and second cables, and causing the cable guard slide to move in a downward path along the proximal portion of the cable guard rod. 
         [0032]    In another embodiment of the present invention, there is included a method of correcting the natural nock travel of a compound bow. The compound bow has a riser, an upper limb, a lower limb, a first cable, a second cable, and at least one cam, and wherein the method comprises the step of mounting a cable guard rod on the compound bow, the cable guard rod having a distal portion attached to the riser, a central portion, and a proximal portion. Additionally, the method includes mounting a cable slide on the cable guard rod so as to support the cable slide at an angle to the travel path of an arrow being discharged by the compound bow, and wherein the cable slide is slidably mounted on the cable guard rod. 
         [0033]    A further set of steps of the method include: drawing a bowstring connected at one end to the upper limb of the compound bow and at the opposite end to the lower limb of the compound bow, and causing the upper limb and the lower limb to flex rearward; and, rotating at least one cam, so as to shift the first and second cables, and causing the cable guard slide to move in a downward path along the proximal portion of the cable guard rod. From that point, the method includes releasing the bowstring to propel the bowstring and the arrow forward and causing the first and second cables to move forward; and, in turn, moving the cable slide upward along the cable guard rod to allow the arrow to move forward without making contact with the cable slide. This insures correction of the angular nock travel  24  of the compound bow by the angular movement of the cable slide, thus substantially eliminating cam tilt. 
         [0034]    The above, and other objects, features and advantages of the present invention, will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0035]      FIG. 1  is a side elevational view of a typical compound bow which could be adapted to support the present invention. 
           [0036]      FIG. 2  is an end view of a typical compound bow which could be adapted to support the present invention. 
           [0037]      FIG. 3  is a section elevational view of a typical compound bow using a roller cable guard. 
           [0038]      FIG. 4  is an enlargement of the end view of  FIG. 2 . 
           [0039]      FIG. 5  is a side view of the cam tilting forces at play during the typical draw cycle of a compound bow. 
           [0040]      FIG. 6  is a top view of the nocking point travel of the typical compound bow. 
           [0041]      FIG. 7  is a top view of the handle torque effect of a compound bow. 
           [0042]      FIG. 8  is a top view of an embodiment of the cable guard rod of the present invention. 
           [0043]      FIG. 9  is a top view of a second embodiment of the cable guard rod of the present invention. 
           [0044]      FIG. 10  is a top view of a third embodiment of the cable guard rod of the present invention. 
           [0045]      FIG. 11A  is a graph of the loads and movements exerted by prior art compound bows. 
           [0046]      FIG. 11B  is a chart of the loads and movements exerted by prior art compound bows. 
           [0047]      FIG. 12A  is a graph of a nock travel plot of a first contemporary, commercially available, compound bow; and, the nock travel plot of the same bow retrofitted with the present invention. 
           [0048]      FIG. 12B  is a graph of a nock travel plot of a second contemporary, commercially available, compound bow; and, the nock travel plot of the same bow retrofitted with the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0049]    Reference will now be made in detail to several embodiments of the invention that are illustrated in the accompanying drawings. Wherever possible, same or similar reference numerals are used in the drawings and the description to refer to the same or like parts or steps. The drawings are in simplified form and are not to precise scale. For purposes of convenience and clarity only, directional terms, such as top, bottom, up, down, over, above, and below may be used with respect to the drawings. These and similar directional terms should not be construed to limit the scope of the invention in any manner. The words “connect,” “couple,” and similar terms with their inflectional morphemes do not necessarily denote direct and immediate connections, but also include connections through mediate elements or devices. 
         [0050]    The preferred embodiments of the present invention are illustrated in  FIGS. 8 ,  9  and  10 . 
         [0051]    Turning first to  FIG. 8 , there is shown a top view of an embodiment of the cable guard rod  10  assembly of the present invention. The assembly has a cable slide  2  profiled to provide fletching  12  and cable clearance  20  when used with an optimized cable guard angle. The cable slide  2  allows the cables  4 ,  6  to pass therethrough. 
         [0052]    The cable guard rod  10 /bracket  22  is mounted, either directly or indirectly, to the bow&#39;s riser  16  of the frame. The cable guard rod  10  is comprised of two parts (an upper half and a lower half) and its corresponding bracket  22 . The cable guard rod  10  and bracket  22  can be made of any material suitable to the purpose, though a preferred embodiment would be the use of aluminum or a composite. The bow&#39;s cables  4 ,  6  are located in a cable slide  2  which slides on the cable guard rod  10 . The sliding block  2  has a means of locating and trapping the bow&#39;s cables to prevent them from contacting each other during normal operation. The cable slide  2  must move laterally approximately 0.6″ towards the arrow  14  within the rearward/forward motion determined by the cable&#39;s  4 ,  6  movement to provide clearance  20  for the fletching  12 . 
         [0053]    There is created an exterior angle  25  from the upper portion of the cable guard rod  10  to the lower portion of the cable guard rod. The lower portion of the cable guard rod  10  being essentially perpendicular to the riser  16 . The actual angle of the cable guard rod  10  is determined by the rearward and forward displacement of the cables to result in the lateral displacement of 0.6″. The angle  25 , which is preferably within the range of 25 to 40°, has been optimized to cause the nocking point/bow string offset to provide arrow  14  fletching  12  clearance at the end of the shot and minimum clearance prior to that point, this causes the nocking point and bowstring travel to closely follow the “natural string path”  28 . 
         [0054]    The cantilever load imposed by the fixed cable guard displacement on the cam(s) and or wheel, as previously discussed with reference to the prior art, causes the tilting which results in nock travel at an angle with respect to the natural travel path. The substantial reduction in the cantilever load by the angled cable guard rod creates a nock travel that tracks essentially straight with respect to the natural travel path of the string/nocking point. 
         [0055]    Turning next to  FIG. 9 , there is shown a top view of a second embodiment of the cable guard rod of the present invention. 
         [0056]    The cable guard rod  10  is preferably a single piece which is mounted to the bow&#39;s riser  16 . The cable guard rod  10  can be made of any material suitable to the purpose, though a preferred embodiment would be the use of aluminum or a composite. The bow&#39;s cables  4 ,  6  are located in a cable slide  2  which slides on the cable guard rod  10 . The cable slide  2  has a means of locating and trapping the bow&#39;s cables to prevent them from contacting each other during normal operation. The cable slide  2  must move laterally approximately 0.6″ towards the arrow  14  within the rearward/forward motion determined by the cable&#39;s  4 ,  6  movement so as to provide clearance  20  for the fletching  12 . 
         [0057]    There is created an exterior angle  25  from the upper portion of the cable guard rod  10  to the lower portion of the cable guard rod. The lower portion of the cable guard rod  10  is essentially perpendicular to the riser  16 . The actual angle of the cable guard rod  10  is determined by the rearward and forward displacement of the cables to result in the lateral displacement of approximately 0.6″. The angle  25 , which is preferably within the range of 25 to 40°, has been optimized to cause the nocking point/bow string offset to provide arrow  14  fletching  12  clearance  20  at the end of the shot and minimum clearance prior to that point, this causes the nocking point and bowstring travel to closely follow the “natural string path”  28 . 
         [0058]    As with  FIG. 8 , the cantilever load imposed by the fixed cable guard displacement on the cam(s) and or wheel, as previously discussed with reference to the prior art, causes the tilting which results in nock travel at an angle with respect to the natural travel path. The substantial reduction in the cantilever load by the angled cable guard rod creates a nock travel that tracks essentially straight with respect to the natural travel path of the string/nocking point. 
         [0059]    With reference next to  FIG. 10 , there is shown a top view of a third embodiment of the cable guard rod of the present invention. 
         [0060]    The cable guard rod  10 /block  44  is mounted, either directly or indirectly, to the bow&#39;s riser  16  of the frame. The cable guard rod  10  is comprised of two parts (an upper half and a lower half) and its corresponding block  44 . The cable guard rod  10  and bracket  22  can be made of any material suitable to the purpose, though a preferred embodiment would be the use of aluminum or a composite. The bow&#39;s cables  4 ,  6  are located in a cable slide  2  which slides on the cable guard rod  10 . The sliding block  2  has a means of locating and trapping the bow&#39;s cables to prevent them from contacting each other during normal operation. The cable slide  2  must move laterally approximately 0.6″ towards the arrow  14  within the rearward/forward motion determined by the cable&#39;s  4 ,  6  movement. 
         [0061]    There is created an exterior angle  25  from the upper portion of the cable guard rod  10  to the lower portion of the cable guard rod  10 . The lower portion of the cable guard rod  10  is essentially perpendicular to the riser  16 . The actual angle of the cable guard rod  10  is determined by the rearward and forward displacement of the cables to result in the lateral displacement of 0.6″. The angle  25 , which is preferably within the range of 25 to 40°, has been optimized to cause the nocking point/bow string offset to provide arrow  14  fletching  12  clearance  20  at the end of the shot and minimum clearance prior to that point, this causes the nocking point and bowstring travel to closely follow the “natural string path”  28 . 
         [0062]    As with  FIGS. 8 and 9 , the cantilever load imposed by the fixed cable guard displacement on the cam(s) and or wheel, as previously discussed with reference to the prior art, causes the tilting which results in nock travel at an angle with respect to the natural travel path. The substantial reduction in the cantilever load by the angled cable guard rod creates a nock travel that tracks essentially straight with respect to the natural travel path of the string/nocking point. 
         [0063]      FIG. 11A  is a graph of the axle load and draw force (in lbs.) on the x-axis relative to the draw length (in inches) on the y-axis, and the cable offset and cam radius of the x′-axis. These plots are used to illustrate the effects on: cam axle load; stock cable offset; the cable offset of the present invention; draw forces; and, the cam radius at the string. 
         [0064]    By referring back to  FIG. 5 , the graph of  FIG. 11A , can be placed in context. The addition of a cable guard  10  and the cable offset  20  imposes a side load  48  on the bow&#39;s cam(s)  30   a,    30   b  which causes a tilt  32  and a change in position of the bow string with respect to its natural travel path. The tilting  32  increases as the bow is drawn and reaches its peak draw weight. This effect imposes much higher loads on the cam axles  34   a,    34   b;  and, therefore, the cams  30   a,    30   b  by the flexure of the limbs  46  which increases dramatically as the bow is drawn. During this latter action, the loads can be as high as 400 lbs. These high loads imposed off center on the cams create a very large load imbalance which causes the cam(s) to tilt. The cam(s) radius also increases through the draw cycle and moves the string farther from the cam(s) center line producing a mechanical advantage for the archer drawing the bow; but, causing even more cam tilting and lateral displacement of the bow string. 
         [0065]      FIG. 11B  is a chart of the values derived from the plot of  FIG. 11A  of the axle load and draw force (in lbs.) on the x-axis relative to the draw length (in inches) on the y-axis, and the cable offset and cam radius of the x′-axis. These plots are used to illustrate the effects on: cam axle load; stock cable offset; the cable offset of the present invention; draw forces; and, the cam radius at the string. 
         [0066]    Turning to  FIG. 12A , there is shown, by way of example, a graph of: a nock travel plot of a first contemporary, commercially available, compound bow; and, the nock travel plot of the same bow retrofitted with the present invention. 
         [0067]    The baseline  28 , or natural travel path, of the specific bow represents the movement of the string if no extraneous forces were acting upon it. The angular nocking point  24 , or actual bow string travel path, is the accumulation of forces that have caused this particular bow string to deviate from the baseline  28 . In this case, the deviation  52  is 5°. When the present invention is retrofitted to this particular bow, the corrected travel path  29  results in a deviation  50  of 0°  30 ′. 
         [0068]    In reviewing the advantageous result of the present invention, we turn next to  FIG. 12B  where there is shown, by way of example, a graph of a nock travel plot of: a second contemporary, commercially available, compound bow; and, the nock travel plot of the same bow retrofitted with the present invention. 
         [0069]    The baseline  28 , or natural travel path, of the specific bow represents the movement of the string if no extraneous forces were acting upon it. The angular nocking point  24 , or actual bow string travel path, is the accumulation of forces that have caused this particular bow string to deviate from the baseline  28 . In this case, the deviation  52  is 2°  48 ′ When the present invention is retrofitted to this particular bow, the corrected travel path  29  results in a deviation  50  of 0°  6 ′. 
         [0070]    In the claims, means or step-plus-function clauses are intended to cover the structures described or suggested herein as performing the recited function and not only structural equivalents but also equivalent structures. Thus, for example, although a nail, a screw, and a bolt may not be structural equivalents in that a nail relies on friction between a wooden part and a cylindrical surface, a screw&#39;s helical surface positively engages the wooden part, and a bolt&#39;s head and nut compress opposite sides of a wooden part, in the environment of fastening wooden parts, a nail, a screw, and a bolt may be readily understood by those skilled in the art as equivalent structures. 
         [0071]    Having described at least one of the preferred embodiments of the present invention with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various changes, modifications, and adaptations may be effected therein by one skilled in the art without departing from the scope or spirit of the invention as defined in the appended claims.