Abstract:
An attachment for a lawnmower which allows simultaneous cutting and trimming operations. The attachment consists of a centrally located housing having a relatively massive main body, a central bore formed in the main body allows for placement of the attachment onto the drive shaft of the mower, the drive shaft coupled to a source of motive power such as a gas powered engine. A plurality of filament coupling areas are evenly spaced about the periphery of the main body of the attachment, each coupling area having a filament extending therefrom. The filaments are of a sufficient length to extend exteriorly of the lawn mower housing to effect trimming operations as the mower is operated in the fringe areas of the lawn.

Description:
1. CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a Continuation in Part of application Ser. No. 12/060,623 filed Apr. 1, 2008. 
     
    
     2. BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to rotary lawn mowers. More particularly, it relates to an attachment for a lawn mower which facilitates simultaneous mowing and trimming. 
       Statement of the Prior Art 
       [0003]    A conventional mower includes a rotary blade attached to a motor driven shaft. The blade, which may be a regular mowing blade or a mulching blade is, for obvious safety reasons, sized to remain within the mower housing, which also includes the motor, wheels for rolling the mower over the lawn surface, and a handle portion extending therefrom which contains the controls and allows a user to roll the mower over the lawn surface. A problem with this arrangement is that fringe areas of the lawn cannot be accessed by the blade. These fringe areas must be trimmed with other tools such as a weed trimmer or mower, adding considerably to the time to complete the mowing job. In the case of a large yard, the additional time consumed by the fringe trimming operation is often considerable, as much as the mowing operation itself. Additionally, these trimmers are not low maintenance, requiring service more frequently than the mower itself as the trimming line must be constantly replaced. Gas powered trimmers require fuel and therefore add greatly to the overall pollution and energy consumption due to lawn maintenance operations. Several attempts have been made to alleviate this problem. U.S. Pat. No. 5,701,728 issued to Koka et al. discloses a lawn mower with a trimming assembly. The trimming assembly consists of a pair of trimming lines mounted directly to the mower blade. The lines extend radially from end portions of the blade. The drawback with this mechanism is that it requires modifications to the mower blade. Specifically, holes must be drilled in the blade in order to position the filament housing onto the blade. Also, the filament housing drastically alters the aerodynamics of the mower blade. Given the speed of rotation of the blade, this aerodynamic change could produce unforeseeable loading on the mower motor, drive shaft and coupling. Also, as the filament housing is proximate end portions of the blade, it is subject to being dislodged or displaced during the mowing operation, especially if tall grass or debris are encountered. Finally, placement of the filament housing at the end portions of the blade results in a higher rotational speed thereof which also increases the possibility of damage to the filament housing or unintended disconnection of the filament from the housing upon impact with debris. U.S. Pat. No. 4,374,465 issued to Comer discloses another trimming line attachment for a mower. The drawbacks with this assembly are the same as for the Koka patent as discussed above. An additional problem with the Comer device is that the attachment means for the filament is actually located on the bottom surface of the blade, where it is highly likely to come into contact with debris such as rocks and cans which could easily dislodge the whole assembly. 
         [0004]    U.S. Pat. No. 4,819,416 issued to Jones discloses an alternate cutting member using filaments which are intended to replace, not supplement, a traditional mower blade. 
         [0005]    None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention, as claimed. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention overcomes the disadvantages of the prior art by providing an attachment for a lawnmower which allows simultaneous cutting and trimming operations. The attachment consists of a centrally located housing having a relatively massive main body. A central bore formed in the main body allows for placement of the attachment onto the drive shaft of the mower, the drive shaft coupled to a source of motive power such as a gas powered engine. A plurality of filament coupling areas are evenly spaced about the periphery of the main body of the attachment, each coupling area having a filament extending therefrom. The filaments are of a sufficient length to extend exteriorly of the lawn mower housing to effect trimming operations as the mower is operated in the fringe areas of the lawn. 
         [0007]    Accordingly, it is an object of the invention to provide an improved lawn mower attachment which facilitates trimming fringe portions of the lawn. 
         [0008]    It is another object of the invention to provide a lawn mower attachment which uses filaments actuated by the lawn mower engine. 
         [0009]    It is another object of the invention to provide a lawn in mower attachment having a relatively massive main body to which a plurality of filaments are attached. 
         [0010]    It is another object of the invention to provide a lawn mower attachment which is connected to the engine output shaft by a single coupling. 
         [0011]    It is another object of the invention to provide a lawn mower attachment which has minimal interference with the lawn mower blade aerodynamics. 
         [0012]    It is another object of the invention to provide a lawn mower attachment which is attached proximate the axis of rotation of the drive shaft to reduce the speed of rotation thereof. 
         [0013]    Finally, it is a general object of the invention to provide improved elements and arrangements thereof in an apparatus for the purposes described which is inexpensive dependable and fully effective in accomplishing its intended purposes. 
         [0014]    These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    Various other objects, features, and attendant advantages of the present invention will become more fully appreciated as the same becomes better understood when considered in conjunction with the accompanying drawings, in which like reference characters designate the same or similar pans parts throughout the several views, and wherein: 
           [0016]      FIG. 1 . shows a plan view of the underside of an exemplary lawn mower employing the attachment of the present invention. 
           [0017]      FIG. 2  shows a perspective view of the lowermost surface of the attachment when installed on the lawn mower. 
           [0018]      FIG. 3  shows a perspective view of the lowermost surface of an alternative embodiment of the attachment when installed on the lawn mower. 
           [0019]      FIG. 4  shows a plan view of another alternative embodiment of the attachment. 
           [0020]      FIG. 5  shows a side sectional view of the alternative embodiment shown in  FIG. 4 . 
           [0021]      FIG. 6  shows a side view of the attachment of  FIG. 4  mounted on the power shaft of a mower. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    Referring now to  FIGS. 1-3  the attachment of the present invention, generally indicated by the numeral  10 , is shown. The attachment  10  is primarily designed for use with riding mowers, but may be used with regular push mowers as is depicted in  FIG. 1 . 
         [0023]    When used with a riding mower, the relatively robust construction of the attachment allows it to withstand many high impact collisions with rocks, bricks, and other debris. It can be readily appreciated by those familiar with landscaping and general lawn maintenance that this type of debris, often encountered when operating mowers in general, poses an even greater risk of damage when encountered by a riding mower as the operator&#39;s view of the ground is shielded by the relatively large housing of the mower. Also, as riding mowers are typically used on much larger lawn areas than push mowers, it can be painstaking if not outright impractical to check the entire lawn for debris. Additionally, the size of lots on which riding mowers are used makes the job of trimming the fringe areas that much more arduous. 
         [0024]    A rotary mower according to this invention is shown as  12  in  FIG. 1 . Mower  12  includes a generally circular housing  14  having a top deck  16  and a circumferentially extending side wall  18  that depends downwardly from deck  16 . Side wall  18  terminates in a lower edge  20 . Together top deck  16  and side wall  18  define a substantially enclosed cutting chamber  22  that encloses a rigid cutting blade  24  made from a suitable metallic material such as steel. 
         [0025]    The housing  14  is supported at a selected height above the ground by any suitable means, such as a plurality of wheels  26 . However, a ground effect air cushion support means or other means may also be utilized. Blade  24  has one or more sharpened cutting edges  27 , and is attached by a blade retainer  28  to a power shaft  70  having a threaded tip  71  which is connected a power source (not shown) which may be any suitable means for rotating blade  24  at a speed sufficient to sever standing vegetation. The power source may be an internal combustion engine, or an electric motor, mounted on deck  16 . When blade  24  is so attached to the power source, the plane of the blade is above the lower edge  20  of side wall  18  for safety. The thickness of the main body  34  of the attachment  10  is selected to ensure that a cutting plane created thereby extends below lower edge  20  to trim areas outside of the mower housing  14  as will be explained in more detail later. 
         [0026]    As has been previously mentioned the attachment has a main body  34  which is relatively massive with respect to the size of the filament or cable used with the invention. Referring particularly to  FIG. 2 , the attachment main body  34  may be made of any suitable sturdy material such as steel or other metal. A high strength plastic or other high strength, non-metallic material may be used to form the main body  34  of the attachment  10 . The main body  34  is substantially disc shaped and has a thickness sufficient to ensure that the plane of rotation of filament or cable  36  extends below the mower housing  12 , but not so far below the housing  12  so that the cable  36  trims standing vegetation substantially lower than the mower blade. It can be appreciated that the cable  36  would quickly wear out if its plane of rotation were substantially lower than the plane of rotation of the mower blade  24 , as most of the vegetation would be severed by the cable  36  and not the mower blade  24 . The filaments or cables  36  are connected at regularly spaced attachment points about the edge portion of the lowermost surface  37  of the attachment main body  34 . The uppermost surface  41  faces the interior surface of the mower deck, the spacing between the uppermost surface  41  and the lowermost surface  37  being such that the plane of rotation of the cables  36  is lower than the lower edge  20  of sidewall  18 . While a standard line trimming filament may be employed, a wire cable having high durability is preferable. Cable clamps  38  or other suitable coupling means are used to hold the cables  36  in position. Centrally located bore  39  extends completely through attachment  10  and is sized to allow placement of the power output shaft  70  of the mower engine therethrough. The dimensions of the inner surface of the bore  39  are such that sufficient frictional engagement with the shaft occurs to help prevent slippage between the shaft  70  and the attachment  10 . Also, the retainer  28  which couples the blade  24  to the shaft  70  will be tightened sufficiently to allow both blade and attachment to rotate with the shaft  70 . Other means for coupling the attachment  10  to the shaft  70  may also be employed as would be apparent to one of skill in the art. 
         [0027]    An alternative configuration for an attachment, generally indicated by the numeral  50  is shown in  FIG. 3 . This embodiment utilizes a substantially rectangular elongated main body  52 . Cables  54  are attached proximate corner portions of the lower surface  56  of the main body  52 . The elongated shape of the main body  52 , in combination with the cables  54  extending from the corner positions of the main body  52  causes rotation of the cables  54  in closely spaced pairs, more closely approximating the cutting action of a mower blade. As with attachment  10  a central bore  59  extends through the main body  52  and the spacing between lowermost surface  56  and uppermost surface  61  establishes a plane of rotation, below the lower edge  20  of the sidewall  18  of the mower deck. This arrangement is more effective against relatively thick standing vegetation. 
         [0028]    A third embodiment of the attachment shown in  FIGS. 4-6  and indicated by the numeral  100 , is especially useful for cutting thick vegetation. Attachment  100  has a main body  102  in the form of a concave disk having an annular downwardly (relative to the top of the mower and extending toward the vegetation to be cut) extending lip  104 . Lip  104  includes spaced pairs of apertures  106 , preferably arranged as four evenly spaced pairs as seen in  FIG. 6 . Cutting cables  108  extend from each of the spaced pairs  106 , the cables  108  looped through the apertures  106  for attachment to the disk  102 , the arrangement allowing for easy removal. A central aperture  110  allows for placement of the disk  102  about the mower shaft  70  as in the previous embodiments. It can be appreciated that the position of lip  104  causes the cables  108  to rotate in a plane below the plane of rotation of the mower blade  24 . Also, the attachment allows for a lower plane of rotation of the cables  108  than the previous two embodiments, and it is a key aspect of the invention that controlling the axial spacing of the cutting cables  54 ,  108  relative to the mower blade  24  allows for more effective trimming and edging. Specifically, the lower the plane of rotation of the cables  54 ,  108  relative to blade  24 , the more effective the trimming and cutting operation especially for cutting through denser vegetation. Preferably, the plane of rotation of the cutting cables  54 ,  108  is about one to two inches below the plane of rotation of the mower blade  24 . 
         [0029]    Installation of the attachments  10 ,  50 ,  100  is accomplished by first removing the retainer  28  which may be a threaded nut and washer threadedly engaged with the end  71  of output shaft  70 . The attachment  10 ,  50 ,  100  is then put in position, with the motor output shaft  70  extending through central bore  39 ,  59 ,  110 . The attachment  10 ,  50 ,  100  will abut a stop (not shown) in the shaft  70 . Retainer  28  is then replaced and sufficiently tightened to ensure co-rotation of the shaft  70 , blade  24 , and attachment  10 ,  50 ,  100 . The plane of rotation of the cables  36 ,  54 ,  108  may then be visually determined. The cables  36 ,  54 ,  108  may be extended manually so that the diameter of the plane of rotation may be observed. Also, a flat elongated surface such as a yardstick, or preferably a level may be used. Utilizing this method the yardstick (not shown) or level (not shown.) is placed flush against the lowermost surfaces  37 ,  56 ,  104  of the main body of attachments  10 ,  50 ,  100  and extended out past sidewall  18 . Visual inspection of the yardstick or level will enable a rapid determination of whether the cables  36 ,  54 ,  108  will extend exteriorly of the sidewall and rotate in a plane which is parallel to the plane of rotation of the blade  24 , when rotated at high speed. If it is determined that the plane of rotation does not extend below the lower edge  20  of the sidewall  18  then an axial spacer (not shown) may be used to adjust the plane of rotation of the cables  36 ,  54 ,  108 . 
         [0030]    In accordance with one embodiment of the invention, the spacer may be the main body  34 ,  52 ,  102  of the attachment. Of course the cables  36 ,  54 ,  108  must be detached from the attachment  10 ,  50 ,  100  if it is to be used as a spacer. Preferably, a used attachment  10  is employed as a spacer. It can be appreciated that a spacer will not normally be needed with the embodiment  100 . 
         [0031]    From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions. 
         [0032]    It is to be understood that the present invention is not limited to the sole embodiment described above, but encompasses any and all embodiments within the scope of the following claims: