Abstract:
A mowing device including a disc, the disc providing a mount for at least one knife, said knife being pivotably mounted to said disc by a pivot pin, said pivot pin defining a mounting axis, such that the knife can rotate about said pivot pin between a first extended position and any retracted position, said disc being constructed of a basic material thickness and comprising a mounting surface; said mowing device including a knife adapter comprising a cylindrical aperture and a projection; said pivot pin comprising a first cylindrical section of a first diameter to fit into said cylindrical aperture in said knife adapter, and a second cylindrical section, of a second diameter, with a groove defined by a groove width and a pin section thickness at the groove of a dimension less than said second diameter; said mowing device including a retainer constructed of a material thickness equal to or less than the width of said groove, with a key-hole shaped aperture defined by a first circular section with a first inside diameter larger than said second diameter of said pin and a slot shaped section with a width that is greater than said pin section thickness but less than said second diameter of said pivot pin; wherein said slot-shaped section of the retainer engages said groove of said pivot pin to retain said pivot pin while said projection of said knife adapter engages said retainer.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a Divisional Application of U.S. Ser. No. 11/062,981, filed Feb. 22, 2005, which is a Continuation-in-Part Application of U.S. Ser. No. 10/912,720, filed Aug. 5, 2004, now U.S. Pat. No. 6,959,530, issued Nov. 1, 2005, which is a Divisional of U.S. Ser. No. 10/387,100, filed Mar. 12, 2003, now U.S. Pat. No. 6,834,486, issued Dec. 28, 2004, and are all incorporated by reference herein in their entirety. 
     
    
     BACKGROUND 
     Field of the Invention 
       [0002]    The present invention relates to mowing device having a pivotal mounting arrangement for mounting a knife to a rotary disc, which makes replacement, or reorientation of the blade possible using only common tools. 
       SUMMARY OF THE INVENTION 
       [0003]    Knives used on rotary disc mowers contact the crop material at high speeds, in order to cut effectively. This results in inherent dulling and wear. At times these knives contact other objects such as the ground, rocks etc. causing additional wear. As a result the knives must routinely be maintained. 
         [0004]    The knives are pivotally mounted to discs, in a manner to reduce impact loading on the sharpened edge when striking an obstacle.  FIGS. 1-4  illustrate a prior art mounting arrangement. Mower disc assembly  10  includes knife adapter  30  that is attached to the bottom side of disc body  20 , retained with bolt  15  which passes through aperture  26  of disc  20  and into threaded aperture  36  of knife adapter  30 . The knife adapter  30  can alternatively be welded to disc body  20 . Knife adapter  30  further includes a cylindrical aperture  32  that is located concentric with a cylindrical aperture  22  of the disc body  20 , together defining the pivot axis of knife  50 . Knife  50  includes a cylindrical aperture  52 , sized to allow sleeve portion  12  of bolt  14  to pass through allowing sufficient clearance so that the knife  50  will pivot freely. The mounting arrangement is completed by installing bolt  14  through the aperture  52  of the blade  50 , then through the aperture  32  of knife adapter  30 , and finally through aperture  22  of disc body  20 , and into its mating nut  16 . 
         [0005]    The top side of the disc body  20  is in contact with the material being cut, functioning to lift and propel the cut material away from the knife. It is exposed to significant wear, along with any components located on the top side of the disc  20 , such as nut  16 . If nut  16  is subjected to sufficient wear, the hex configuration of its outer surface can be degraded to the point that a wrench no longer mates adequately to allow removal. In order to protect the nut  16  from this excessive wear prior art mounting arrangements have included a wear protector  17  mounted on the top of the disc body, to protect the nut  16  from this excessive wear. 
         [0006]    Disc  20  is adapted to provide for this mounting arrangement by providing mounting surface  24  on disc body  20  for supporting wear protector  17 . The disc  20  further includes a transition area to the raised portion  28 . This raised portion  28  tapers such that at the far outer diameter of the disc  20 , it does not exist. At lesser diameters the raised portion is increasingly larger. This raised portion  28 , and the transition area between it and the mounting surface  24 , provides protection for bolt  15 , which thus does not require a wear protector. 
         [0007]    The knife adapter  30  often includes a tab  34  that prevents full rotation of the knife  50 , in order to control its location, in order to avoid interference with other components of the machine. 
         [0008]    This mounting arrangement requires that the several pieces be disassembled with wrenches in order to maintain the knives which is costly and difficult due to the number of knives on a machine. 
         [0009]    According to the present invention there is provided a mowing device having an improved mounting arrangement for a knife to a disc as follows from the appended claims. In addition it provides a method of removing the knife from the disc without the use of wrenches, simply requiring a tool to pry, such as a screw driver. In addition the present invention relates to a knife adapter for use in such a mowing device. A further feature is a low profile retainer that does not need to be protected by a wear protector. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0010]      FIG. 1  is an exploded view of a prior art mounting arrangement of a knife onto a mower disc; 
           [0011]      FIG. 2  is a partial top plan view of a mower disc with knife mounted in accordance with the prior art as illustrated in  FIG. 1 ; 
           [0012]      FIG. 3  is a top plan view of a knife adapter of the prior art knife mounting; 
           [0013]      FIG. 4  is a partial top plan view of the mower disc configured for the prior art knife mounting; 
           [0014]      FIG. 5  is a top plan view of a mower disc with knives mounted in accordance with the present invention; 
           [0015]      FIG. 6  is a bottom plan view of a mower disc with knives mounted in accordance with the present invention; 
           [0016]      FIG. 7  is a cross-sectional side view of a mower disc, as defined by section line  7 - 7  in  FIG. 6 , with the knives mounted in accordance with the present invention; 
           [0017]      FIG. 7   a  is a view like  FIG. 7 , but of a slightly modified version wherein the retainer is not completely flat in the retained position so that it is easier to get a screwdriver under it for removal at a later time; 
           [0018]      FIG. 8  is a top plan view and an exploded view of the mounting arrangement of a knife onto a mower disc of the present invention; 
           [0019]      FIG. 8   a  is an exploded view of  FIG. 7 ; 
           [0020]      FIG. 9  is a partial top plan view of the mower disc configured for the knife mounting arrangement of the present invention; 
           [0021]      FIG. 10  is a top plan view of a blade retainer of the knife mounting arrangement of the present invention; 
           [0022]      FIG. 11  is a top plan view of a knife adapter of the knife mounting arrangement of the present invention; 
           [0023]      FIG. 12  is a top plan view of a mower disc with knives mounted in accordance with a second embodiment of the present invention; 
           [0024]      FIG. 13  is a bottom plan view of a mower disc with knives mounted in accordance with a second embodiment of the present invention; 
           [0025]      FIG. 14  is a cross-sectional side view of a mower disc, as defined by section line  14 - 14  in  FIG. 13 , with the knives mounted in accordance with a second embodiment of the present invention; 
           [0026]      FIG. 15  is a partial top plan view of the mounting arrangement of a knife onto a mower disc of a second embodiment of the present invention; 
           [0027]      FIG. 15   a  is an exploded view of  FIG. 14 ; 
           [0028]      FIG. 16  is a partial top plan view of the mower disc configured for the knife mounting arrangement of a second embodiment of the present invention; 
           [0029]      FIG. 17  is a top plan view of a blade retainer of the knife mounting arrangement of a second embodiment of the present invention; 
           [0030]      FIG. 18  is a top plan view of a knife adapter of the knife mounting arrangement of a second embodiment of the present invention; 
           [0031]      FIG. 19  is a side view of a retaining pin of the present invention; 
           [0032]      FIG. 20  is a side view of a second embodiment of a retaining pin of the present invention; 
           [0033]      FIG. 21  is a top plan view of a retainer of the knife mounting arrangement of the present invention illustrating features to aid disassembly; 
           [0034]      FIG. 22  is side view of an alternate embodiment of a retainer; and 
           [0035]      FIG. 23  is a perspective view of the retainer in  FIG. 22 . 
           [0036]      FIG. 24  is a top plan view of the mower disc configured for the knife mounting arrangement and a knife mounted in accordance with a third embodiment of the present invention; 
           [0037]      FIG. 25  is a cross-sectional side view of a mower disc, as defined by section line A-A in  FIG. 24 , with a knife mounted in accordance with a third embodiment of the present invention; 
           [0038]      FIG. 26  is a partial, perspective plan view of a mower disc with a knife mounted in accordance with a third embodiment of the present invention; 
           [0039]      FIG. 27  is a perspective plan view of the knife adapter; 
           [0040]      FIG. 28  is a partial, cross-sectional side view of a mower disc, as defined by section line A-A in  FIG. 24 , with a knife mounted in accordance with a third embodiment of the present invention; 
           [0041]      FIG. 29  is a cross-sectional side view taken on the centerline of the knife adapter in accordance with a third embodiment of the present invention; 
           [0042]      FIG. 30  is a perspective view of the fastening pin by means of which a knife is mounted in accordance with a third embodiment of the present invention; 
           [0043]      FIG. 31  is a top plan view of a retainer of the knife mounting arrangement of the third embodiment of the present invention; 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0044]    Referring now to the drawings, like reference numerals designate identical or corresponding parts throughout the several views. The included drawings reflect the current preferred and alternate embodiments. There are many additional embodiments that may utilize the present invention. The drawings are not meant to include all such possible embodiments. 
         [0045]    The  FIGS. 5-7  illustrate a mower disc assembly  110  of the present invention. A disc  120  includes a center pilot hole  112  that controls its alignment and location when installed onto a cutter bar which is comprised of a series of gears, a supporting frame/housing, and driveline to transfer power from a tractor PTO to the cutterbar. Additional holes  114  allow retainers, not shown, to securely attach other components such as crop deflectors, not shown, to the mower disc. Two knives  50  are installed onto the bottom of disc body  120 , each with a knife adapter  130 , a pin  140  and a retainer  150 . The knife is free to rotate about pivot axis  116  until it contacts a tab  134  of the knife adapter  130 . 
         [0046]      FIGS. 8-11  further illustrate a single knife mount of this embodiment of the present invention. The disc body  120  includes two cylindrical apertures  122  and  126 , and a mounting surface  124 , as illustrated in  FIG. 9 , on each side, for each knife  50 . It further includes a transition between the mounting surface  124  and raised portion  128 . 
         [0047]    The knife adapter  130  includes a cylindrical aperture  132 , a tab  134 , and a cylindrical projection  136  as illustrated in  FIGS. 8 ,  8 A and  11 . The knife adapter  130  is fixedly attached to the bottom side of disc body  120 , the preferred attachment method is welding, such that cylindrical projection  136  passes through aperture  126  of disc body  120  and extends above the mounting surface  124 . 
         [0048]    Pin  140  includes a first cylindrical portion  142  with a diameter slightly smaller than the aperture  52  in the blade  50 , and a second cylindrical portion  144  that is slightly smaller than the aperture  122  of disc  120 . It also includes a head portion  148  with a diameter larger than the aperture  52  in the knife  50 . It further includes a retaining groove  146 , located on the second cylindrical portion  144 , with a width that slightly exceeds the thickness of retainer  150 , and has a groove diameter that is smaller than the diameter of the second cylindrical portion  144 . 
         [0049]    Retainer  150  is made of a spring material of a thickness such that a significant force is required in order to deflect the retainer  150 , yet it can be deflected significantly without being permanently deformed. This thickness is equal to or less than the material thickness of the disc body  120 . It includes a key-hole shaped aperture  152  with a first end  154  and a second end  156 . The first end  154  is wide enough that retainer  150  can be installed over the second end  144  of pin  140 . The second end  156  of the key-hole aperture  152  is cylindrical with a diameter slightly larger than the groove  146  of pin  140 . 
         [0050]    The blade  50  is mounted to the disc by passing pin  140  through the aperture  52  in knife  50 , then through aperture  132  in knife adapter  130  and aperture  122  in disc  120  such that groove  146  is located above surface  124 . Pin  140  is retained in this position by placing retainer  150  onto the pin, passing the first end of the key-hole aperture  152  over the second end  144  of pin  140  until the retainer is against the surface  124  of disc  120 . The retainer is then slid perpendicular (right in  FIGS. 8 and 8A ) to the pin  140 , such that the second end  156  of the keyhole shaped aperture  152  engages the groove  146 . 
         [0051]    As retainer  150  is being slid along surface  124  a leading side  158  will come in contact with the ramped surface  138  of cylindrical projection  136  of knife adapter  130 , which is extending above surface  124 , through aperture  126  of disc  120 . In order to slide retainer  150  to its proper position the retainer will be deflected up the ramped portion  138  of knife adapter  130 . Upon reaching the installed position the retainer  150  will snap positively into place when first end of key-hole shaped aperture  152  slips over the cylindrical portion  136  of knife adapter  130 , at such time the retainer  150  will return back towards its unloaded position, where it is straight as illustrated in  FIG. 8A . Alternatively curved retainer  151 , with a slight bend, could be utilized. If the curved retainer  151  is utilized, then it will snap towards its unloaded position represented by this slightly curved shape. In this position as shown in  FIG. 8 , the retainer  150  is held in position by the cylindrical projection  136 . In order for it to move along surface  124  the leading side  158  of retainer  150  will need to be deflected far enough to clear the cylindrical projection  136  of blade retainer. In this manner, the pin  140  and knife  50  are retained to the disc  120 , and removal of a knife  50  can be accomplished simply by using a tool capable of prying the leading end  158  of retainer  150  up and over the cylindrical projection  136  to the point it can be slid along surface  124 . The removal operation is enhanced if the leading edge  158  is raised slightly above the top surface  124 . This slightly raised area can be provided by a slightly curved retainer  151 , or by providing an additional small step  139  as illustrated in  FIG. 7A . 
         [0052]    This mounting arrangement of  FIGS. 5-8  thus provides a knife retention system that includes a retainer with a material thickness less than the material thickness of the disc, and a pin which does not require substantial wear protection. The raised portion  128  of the disc body  120  adequately protects the pin  140 , thus there is no need for an additional wear protector. The overall height of the retaining components is small, minimizing the potential affect on the standing crop that is being cut. 
         [0053]      FIGS. 12-14  illustrate a second embodiment of a mower disc assembly  210  of the present invention. A disc  220  includes a center pilot hole  212  that controls its alignment and location when installed onto a cutter bar. Additional holes  214  allow retainers, not shown, to securely attach other components such as crop deflectors, not shown to the mower disc. Two knives  50  are installed onto the bottom of disc body  220 , each with a knife adapter  230 , a pin  240  and a retainer  250 . The knife is free to rotate about pivot axis  216  until it contacts a tab  234  of the knife adapter  230 . 
         [0054]      FIGS. 15-18  further illustrate a single knife mount of this embodiment of the present invention. The disc body  220  includes one slot-shaped aperture  222 , and a mounting surface  224 , as illustrated in  FIG. 16 , on each side, for each knife  50 . The previously described embodiment could also be implemented with a disc body configured in this manner, if the knife retainer  130  were configured in accordance. Disc body  220  further includes a transition between the mounting surface  224  and raised portion  228 . 
         [0055]    The knife adapter  230  includes a cylindrical aperture  232 , a tab  234 , and a projection  236  shaped to fit into the slot-like aperture  222  of disc  220 , as illustrated in  FIGS. 15 and 18 . Projection  236  includes a surface  237  and further includes a top portion  238  with ramped tabs  260 . The knife adapter  230  is fixedly attached to the bottom side of disc body  220 , the preferred attachment method is welding, such that projection  236  passes through aperture  222  of disc body  220  and top portion  238  extends above the mounting surface  224  while surface  237  is in-line with mounting surface  224 , or is slightly raised above surface  224 . However, an embodiment in which the knife adapter is releasable attached to the disc by means of bolts or screws will be later described with reference to  FIGS. 24 to 28 . 
         [0056]    As illustrated in  FIG. 15A , pin  240  includes a first cylindrical portion  242  with a diameter slightly smaller than the aperture  52  in the blade  50 , and a second cylindrical portion  244  that is slightly smaller than cylindrical portion  244 . It also includes a head portion  248  with a diameter larger than the aperture  52  in the knife. It further includes a retaining groove  246 , located on the second cylindrical portion, with a width that slightly exceeds the thickness of retainer  250 , and has a groove diameter that is smaller than the diameter of the second cylindrical portion  256 . 
         [0057]    Retainer  250  is made of a spring material of a thickness such that a significant force is required in order to deflect the retainer, yet it can be deflected significantly without being permanently deformed. It includes a key-hole shaped aperture  252  with a first end  254  and a second end  256 . The first end  254  is wide enough that retainer  250  can be installed over the second end  246  of pin  240 . The second end  256  of the key-hole aperture  252  is cylindrical with a diameter slightly larger than the groove  246  of pin  240 , and smaller than the diameter of the second end  244  of pin  240 . The retainer  250  further includes two notches  257 , one on each side. Retainer  250  will have an unloaded shape, which is flat as illustrated in  FIG. 15A . It could alternatively include a slightly bent portion at the leading edge  258 , to assist removal, as previously described for retainer  151 . 
         [0058]    The blade  50  is mounted to the disc by passing pin  240  through the aperture  52  in knife  50 , then through aperture  232  in knife adapter  230  such that groove  246  is located above surface  237  or  224 . Pin  240  is retained in this position by placing retainer  250  onto the pin, passing the first end  254  of the key-hole aperture  252  over the second end  244  of pin  240  until the retainer is against the surface  224  of disc  220  or surface  237  of knife retainer  230 . The retainer is then slid perpendicular to the pin  240 , such that the second end  256  of the keyhole shaped aperture  252  engages the groove  246 . 
         [0059]    As retainer  250  is being slid along surface  226  or  237  a leading side  258  will come in contact with ramped tabs  260  of knife adapter  230 , which extend above surface  224  and/or surface  237 , through aperture  222  of disc  220 . In order to slide to its proper position the retainer will be deflected up the ramped tabs  260  of knife adapter  230 . Upon reaching the installed position the retainer  250  will snap into place when notches  257  align with the ramped tabs  260  of knife adapter  230 , the retainer  250  returning back towards it unloaded position where it is straight as shown in  FIG. 15 . In this position, the retainer  250  is held in position by the tabs  260 . In order for it to move along surface  224  or  237 , the leading side  258  of retainer  250  will need to be deflected up, far enough to clear the ramped tabs  260  of knife adapter  230 , before it can be slid along surface  224  or  237 . In this manner, the pin  240  and knife  50  are retained to the disc  220 , and removal of a knife  50  can be accomplished simply by using a tool capable of prying retainer  250  up to the point it can be slid along surface  124  or  237 . The prying tool can, for example, be a screw driver and the leading edge may be held from the surface  124  by a tab, such that the retainer  250  is slightly deflected in the installed position, or by the fact that the retainer includes a slight bend. 
         [0060]    The ramped tabs  260  of knife adapter  230  and the cooperating notches  257  of retainer  250  in this second embodiment provide the same function as the projection  136  and first end  154  of aperture  152  of the first embodiment. These are examples of many different types of arrangements that could be utilized to secure the retainer to the knife adapter, or a different feature of the mower disc itself. 
         [0061]    The retainers, as in retainer  150  and  250 , may include slot  300 , as illustrated in  FIG. 21 , which is provided for disassembly. The slot  300  will be sized and positioned such that a screwdriver, or the like will be able to be utilized to engage the slot in order to assist in prying on the retainer to slide it relative to the disc. 
         [0062]    Additional slots, such as slot  302  shown in  FIG. 21 , or other surface features may be added in order that the retainers will break at defined locations during disassembly. Thus, when the retainer is pried-on to remove the knife, the section of the retainer that is engaged with the tabs or projections of the knife adapter or disc will separate from that portion that is engaged with the pin. This would allow both of the resulting pieces to be easily removed. 
         [0063]      FIGS. 19 and 20  illustrate optional configurations of the grooves in the pin  140  and  240 . The grooves could be full annular grooves  247  as illustrated in  FIG. 19 , or slots  245 , one on each side as illustrated in  FIG. 20 . 
         [0064]      FIGS. 22 and 23  illustrate an additional embodiment of a retainer  350  with an additional curved section  352 . The end  354  is narrow enough to fit into the key-hole slot of the retainer, similarly shaped to the key hole slots in retainers  130  and  230 . The end  354  will then engage with the groove in the pin to increase the bearing surface under the pin head and providing a locking feature that prevents the retainer  350  from sliding. End section  356  forms a tapered profile, approximately paralleling the raised portion  128 ,  228  of disc  120 ,  220  such that the disc  120 ,  220  will protect it. 
         [0065]      FIGS. 24 to 31  illustrate a further alternate embodiment according to the invention. These figures illustrate a third embodiment of a mower disc assembly  310  of the present invention. A disc  320  includes a center pilot hole  312  that controls its alignment and location when installed onto a cutter bar. Additional holes  314  allow retainers, not shown, to securely attach other components such as crop deflectors, not shown, to the mower disc. Two knives  50  are installed onto the bottom of the disc body  320 . The  FIGS. 24-26  and  28  illustrate a single knife mount of this embodiment of the present invention. The disc body  320  includes one aperture  322  and a surface  324 , as illustrated in  FIGS. 24 and 25 , on each side, for each knife  50 . Furthermore, the disc body  320  includes a transition between surface  366  and raised portion  328 . Each knife is mounted by means of a knife adapter  330 , a pin  340  and a retainer  350 . These elements will now first be described separately. 
         [0066]    The knife adapter  330 , which is shown as a separate unit in  FIGS. 27 and 29 , is shaped to fit into the aperture  322  of disc  320 . The knife adapter  330  is fixedly attached to the bottom side of disc body  320 . On one side the knife adapter has a v-shaped groove  390 ; on its other side a screw thread  370  is tapped into the knife adapter. On mounting, the side of the knife adapter including the tapped hole  370  is first inserted into the aperture  322 , subsequently the v-groove of the knife adapter is brought into contact with the edge of aperture  322  which is located closest to the circumference of the disc  320 , and finally a vertically slightly slanting edge  383  of the knife adapter, located opposite the v-groove, is slid into the aperture of the disc  320 . The slightly slanting edge  383  ensures a desirable fastening clamping of the knife adapter in the aperture of the disc  320 . By means of a bolt connection, preferably a bolt  371  with a space-saving (flat) head, the knife adapter  330  is fixedly mounted to the bottom side of disc body  320 . After mounting, the situation as shown in  FIGS. 24 ,  25 ,  26  and  28  is obtained. The knife adapter includes a cylindrical aperture  332  and a tab  334 . The upper side of the knife adapter  330  includes a base plane  380  for a retainer. Said base plane includes ramped tabs  360  and  361 , of which tab  360  has the main function of attaching the retainer. On both sides of the base plane  380  of the retainer there are provided two thick edges  381 . The greatest distance between the edge ends is greater than the width of the aperture  322  in the disc  320 . 
         [0067]    As illustrated in  FIGS. 28 and 30 , the fastening pin  340  for the knife mounting includes a first cylindrical portion  342  with a diameter slightly smaller than the fastening aperture in the blade  50 , and a second cylindrical portion  344  that is slightly smaller than cylindrical portion  342 . It also includes a head portion  348  with a diameter larger than the aperture in the knife. It further includes a retaining groove  346 , located on the second cylindrical portion, with a width that slightly exceeds the thickness of retainer  350 , and consisting of slots, one on each side as illustrated in  FIG. 30 . 
         [0068]    The retainer  350 , shown in  FIG. 31 , is made of a spring material of a thickness such that a significant force is required in order to deflect the retainer, yet it can be deflected significantly without being permanently deformed. It includes a slot-shaped aperture  352  with a first end  354  and a second end  356 . Aperture  352  is wide enough that retainer  350  can be installed over the second end  344  of pin  340 . The width of second end  356  of the slot-shaped aperture  352  is slightly larger than the groove  346  of pin  340 , and smaller than the diameter of the second end  344  of pin  340 . Retainer  350  will have an unloaded shape, which is flat as illustrated in  FIG. 31 . It could alternatively include a slightly bent portion at the side of slide  358 , to assist removal, as previously described for retainer  151 . 
         [0069]    The blade  50  is mounted to the disc by passing pin  340  through the aperture in knife  50 , then through aperture  332  in knife adapter  330  such that groove  346  is located above surface  380 . Pin  340  is retained in this position by placing retainer  350  onto the pin, passing the aperture  352  over the second end  344  of pin  340  until the retainer is against the base plane  380  of knife adapter  330 . The retainer is then slid perpendicular to the pin  340 , such that the second end  356  of the aperture  352  comes into contact with the second end  344  of pin  340 . After mounting, the knife is free to rotate about pivot axis  316  until it contacts a tab  334  of the knife adapter  330 . 
         [0070]    The slots of retaining groove  346  on both sides of pin  340  prevent pin  340  from rotating in the connection. Destructive pin wear is thus prevented in a simple and effective manner. 
         [0071]    As retainer  350  is being slid along surface  380  the leading slide  358  will come into contact with ramped tabs  360  and  361  of knife adapter  330 , which extend above surface  380 . In order to slide to its proper position the retainer will be deflected up the ramped tabs  360  and  361  of knife adapter  330 . On reaching the installed position the retainer  350  will snap positively into place when first end  354  of shaped aperture  352  slips over ramped tab  360 . As the base plane for the leading slide  358  is located somewhat higher than base plane  380 , the retainer  350  will not completely return towards its unloaded position. There is now pre-tension in retainer  350 , which contributes to an enhanced clamping. The presence of ramped tab  361  is the result of further safety-thinking. If the situation should ever occur that the retainer  350  looses contact with ramped tab  360 , ramped tab  361  will ensure a second safety guarantee. In this case retainer  350  will catch behind ramped tab  361 . The engagement of the part of the retainer that is inside the slots of pin  340  is maintained when the retainer has been slid from catching ramped tab  360  to catching ramped tab  361 . Therefore, in this situation a complete blocking of pin  340  is maintained. Breaking of the bolt  371  by means of which the knife adapter is fastened in the disc  320  does not create a dangerous situation owing to the fact that the greatest distance between the ends of the thick edges  381  is greater than the width of the aperture  322  in the disc  320 . If breaking should ever occur, then the thick edges  381  of the knife adapter will ensure that the knife adapter will not come loose from the disc. The thick edges  381  of the knife adapter further ensure protection against wear and damage of the components of the knife fastening concept that are located inside the edges, in particular of the fastening pin and the retainer. The knife fastening is thus properly secured. 
         [0072]    The ramped tabs  360  and  361  of knife adapter  330  secure the retainer to the knife adapter. In the normal fastening position, the retainer  350  is held in position by the tab  360 . Removal of a knife  50  can be accomplished simply by using a tool capable of prying slide  358  of retainer  350  up and over the ramped tabs  360  and  361  to the point it can be slid along surface  380 . The removal operation is enhanced if slide  358  is raised slightly above the top surface  382  or hangs over to some extent. In order for it to move along surface  380 , slide  358  of retainer  350  will need to be deflected up, far enough to clear the ramped tabs  360  and  361  of knife adapter  330 , before it can be slid along surface  380 . This can be accomplished simply by using a tool capable of prying retainer  350  up to the point it can be slid along surface  380 . The prying tool is disposed for example between the fastening bolt of the bolt connection between the knife adapter and slide  358  of retainer  350 . By means of a pushing movement against the rear side  358  of the retainer the latter is slid gradually in a direction away from the disc center. When the retainer is pried-on to remove the knife, the section of the retainer that is engaged with the groove of pin  340  will separate from that portion at the moment when the retainer has been slid to such an extent that aperture  352  surrounds the retainer. Pin  340  and knife  50  can now easily be removed. The prying tool can for example be a screw driver. The retainer may include slot  300 . The slot  300  will be sized and positioned such that a screwdriver or the like will be able to be utilized to engage the slot in order to assist in prying on the retainer to slide it relative to the base plane of the knife adapter. 
         [0073]    Still referring to  FIGS. 24-31 , an apparatus for a mower is shown having a disc  320  adapted to rotate about an axis of rotation. While the word “disc” is used herein, “disc” in this document is defined as any member of any shape that can be disposed for rotation about an axis. The disc  320  has a first aperture  322  disposed therein, the aperture  322  including an inner side  322   a  nearest the axis of rotation, first and second sides  322   b  &amp;  322   c  and a outer side  322   d . The disc  320  also includes a second aperture  326  spaced from the first aperture  322 . An adaptor  330  has a groove  381  configured to engage the first and second sides of the aperture  322  in the disc. 
         [0074]    A first opening  370  is disposed in the adaptor  330 , the first opening  370  being located to align with the second aperture  326  in the disc  320  when the groove  381  is properly engaged with the outer side of the first aperture  322  in the disc  320 . There is also a second opening  332  in the adaptor  330 . 
         [0075]    A ramp section  360  is disposed on the adaptor  330 . A first fastener  371  passes through the second aperture  326  in the disc  330  and into the first opening  370  in the adaptor  330 . 
         [0076]    There is also a second fastener  340 . A knife  50  is secured to the disc  330  by the second fastener  340  passing through the second opening  332  of the adaptor  330 . The second fastener  340  includes at least one slot  346 . 
         [0077]    There is also a third fastener  350  having a keyhole shaped hole  352 . A small section of the keyhole shaped hole  352  is configured to engage with the at least one slot  346  in the second fastener  340  and an enlarged section of the keyhole shaped hole  352  is configured to engage with the ramp section  360  of the adaptor  330  such that the second fastener  340  is retained in position with the adaptor  330 . The adaptor  330  is thereby secured to the disc  320  independently of the first fastener  371 . 
         [0078]    Obviously many modifications and variations of the present invention are possible in light of the above teachings, including variations in the shape of the knife mount pin and cooperating apertures in the knife adapter. It is known to use various configurations of these components, other than the herein specified cylindrical shapes. These would include conical sections, and could include pins with various cross-sections such as square or hexagonal. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.