Abstract:
A double chain saw arrangement which has diametrically oppositely extending chain saws powered by a single motor driving two sprockets on said hub, each engaged with an associated chain saw chains on each chain saw bar mounted to the hub. A series of hooked capture pieces project from one side of the chain saw bars in a plane parallel to the chain saw bars, which pieces act to cause brush and limbs to be captured and forced into contact with the saw chains to be cut thereby.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. provisional patent application No. 61/126,117 filed on May 1, 2008. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention concerns brush cutting and tree delimbing carried out in keeping hiking and snowmobile trails, right of ways for utilities, etc., clear of vegetation. 
     Such operations involve cutting brush and tree limbs which grow into the trail space. Trail systems are extensive, extending for miles such that power equipment has been developed for this purpose, comprising a wheeled groomer vehicle having cutting devices mounted on a boom able to be maneuvered to either side of the trail. 
     The space defined across and above the trail is large and thus the utility to sweep that space with cutting tools in a minimum time is a prime advantage in carrying out the trail grooming. 
     A chain saw attached to a boom has been employed to cut free limbs, but are slow since each limb must be cut individually. Chain saws are generally ineffective to cut twigs and brush as they are often just pushed away from the saw chain. 
     Chain saws of a length beyond the standard length are costly such that the size of the swath able to be cut is limited as a practical matter. 
     It is an object of the present invention to provide a cutting device which can rapidly and effectively cut a wide swath of brush as well as several tree limbs at one time but which also is moderate in cost to manufacture. 
     SUMMARY OF THE INVENTION 
     The above object and other objects which will become apparent upon a reading of the following specification and claims are achieved by a boom mountable double chain saw in which two chain saw bars project out in diametrically opposite directions from a central hub where two aligned chain sprockets are mounted driven by a drive motor which can be electric or hydraulic. 
     A series of mildly hooked capturing pieces are mounted, projecting from one said of both saw chain bars which capture limbs and brush which are forced in against the chain by engagement with the capturing pieces and by the boom and chain motions so as to be quickly cut. 
     The intermediate central location of the drive motor between the chain saws allows cutting close to the ground while keeping the drive motor sufficiently high when cutting close to the ground with the lower chain saw to reduce the vulnerability of the motor and the connections, hoses, etc., to impact with rocks, etc. 
     The double chain saw arrangement can be mounted to the outer end of a vehicle carried boom, with connections providing for pivoting to different angles with respect to the boom. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a pictorial view of a groomer vehicle equipped with a double chain saw arrangement according to the invention. 
         FIG. 2A  is an enlarged pictorial view of the double chain saw arrangement shown in  FIG. 1  with a pivotal mount and a fragmentary portion of a supporting boom. 
         FIG. 2B  is a side view of the double saw arrangement showing a different position of the pivot connection. 
         FIG. 2C  is a side view of the double saw arrangement showing the second pivot connection. 
         FIG. 3  is a front view of the double chain saw arrangement shown in  FIGS. 1 and 2 . 
         FIG. 4  is an exploded pictorial view of the components of the double chain saw arrangement shown in  FIGS. 1-3 . 
         FIG. 5  is an enlarged sectional view of the center hub portion of the double chain saw arrangement shown in  FIGS. 1-4   
         FIG. 6  is a fragmentary end view of hub components shown in  FIG. 5 . 
         FIG. 7  is a fragmentary pictorial end view of the hub showing the sprockets and adjacent portions of the chain saw bars and saw chains. 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description, certain specific terminology will be employed for the sake of clarity and a particular embodiment described in accordance with the requirements of 35 USC 112, but it is to be understood that the same is not intended to be limiting and should not be so construed inasmuch as the invention is capable of taking many forms and variations within the scope of the appended claims. 
     Referring to  FIG. 1 , the present invention comprises a double chain saw arrangement  10  useful for cleaning brush and tree limbs along trails, rights of way, etc., mounted on a boom  12  attached to a grooming vehicle  14  of a known type. 
     The double chain saw arrangement  10  can be mounted to the end of the boom  12  in various orientations about two different axes by two manually adjusted pivot connections  16 ,  18  ( FIGS. 2 ,  2 A,  2 B) as desired. A square tube connector piece  15  projects from connection  18  to allow mounting to the end of the boom  12   
     The details of these connections are not part of the present invention and hence are not here described further. 
     A double chain saw arrangement  10  according to the invention comprises the combination of two chain saws  20 A,  20 B connected to a hub  22  so as to extend end to end in diametrically opposite directions. This doubles the swath able to be cut by a single standard chain saw without requiring an expensive special long chain saw. 
     Both chain saws  20 A,  20 B include conventional chain saw bars  24 A,  24 B comprising flat pieces of steel having a round nose at one end and a slot at the other end secured to the hub  22 . Saw chains  26 A,  26 B recirculate in a groove extending around the perimeter of respective bars  24 A,  24 B ( FIG. 7 ) and around a respective drive sprocket  28 A,  28 B in the well known manner. 
     The sprockets  28 A,  28 B are both fixed on an output shaft  30  of a drive motor  32 , such as a hydraulic motor  32 . An electric motor can also be employed. A sprocket retainer  66  and spacer  68  hold the sprockets  28 A,  28 B in position on the shaft  30 . 
     The chain saw bars  24 A,  24 B are preferably of a standard length and configuration, i.e., each 3 feet long to create a total cutting swath of six feet without resorting to expensive non-standard long length chain saws such as are used in logging large trees. 
     The hub  22  includes an index mount plate  34  having a bore receiving the motor  32  and attached to a chain saw bar mounting plate  36  with bolts  37  and nuts  39  ( FIGS. 4 and 7 ). 
     The chain saw bar mounting plate  36  has a step  38  providing two mounting faces  40 A,  40 B for the respective bars  24 A,  24 B against which the bars  24 A,  24 B are respectively clamped as described below. This step  38  slightly offsets the bars  24 A,  24 B so as to be aligned with the side by side sprockets  28 A,  28 B. 
     The bar mounting plate  36  has pairs of studs  42 A,  42 B secured therein aligned on a rib  44 A,  44 B projecting into the conventional lengthwise extending end slot in each chain saw bar  24 A,  24 B to positively hold the bars  24  in their opposing orientation. 
     Separate chain saw bar mounting plates  46 A,  46 B have holes aligned with the studs  42 A,  42 B so as to receive the same and be secured with nuts  43 , to enable clamping the inner ends of the bars  24 A,  24 B to the respective face  40 A,  40 B installed thereon. The studs  42 A,  42 B pass through the end slots in the bars  24 A,  24 B in similar fashion to conventional chain saws. 
     Each of the conventional chain loops  26 A,  26 B ( FIG. 7 ) recirculating in tracks in the bars  24 A,  24 B and around a respective sprocket can be periodically tensioned in a conventional fashion, as by advancing adjusting screws  50 A,  50 B received in the plates  46 A,  46 B and threadedly engaging a respective traveler  52 A,  52 B each have a projecting pin which protrudes into the associated chain saw bar end slot to advance of the bars  24 A,  24 B allowed when the nuts  48  are loosened. Thereafter are the nuts  48  retightening when the correct chain tension is achieved. 
     According to another aspect of the invention a series of brush-limb capture pieces  54  are attached along one side of each bar  24 A,  24 B. The pieces  54  are mildly hooked towards the direction of advance of the chains  26 A,  26 B (indicated in  FIGS. 3 and 7 ), which is the same for both chains since the sprockets  28 A,  28 B are rotated in the same direction. The capture pieces  54  lie in a plane parallel to the plane of the bars  24 A,  24 B and project out past the saw chains  26 A,  26 B, so that spacers  56  are provided to insure that no interference between the chains  26 A,  26 B and the capture pieces  54  will occur. Clamping plates  58  receive suitable threaded fasteners to attach the capture pieces  54  to one side of the bars  24 A,  24 B. The motion of the chains  26 A,  26 B and the boom  12  carries brush and limbs against the capture pieces  54  which then holds them against the chain to insure subsequent complete cutting by the chains  26 A,  26 B. 
     A center guide plate  60  has opposite sloping sides to move the brush and limbs into either of the chains  24 A,  24 B. 
     Cover pieces  62 A,  62 B are installed on the rear side of the bars  24 A,  24 B to protect against impacts and the entanglement of brush with the return run of the chains  26 A,  26 B. 
     A center cover guard  64  is installed over a sprocket retainer  66  to protect the sprocket components and chain segments passing around the sprockets  28 A,  28 B.