Abstract:
A tree shear apparatus includes first and second blades, and linkage means interconnecting the blades so that the first blade makes a partial, relatively small cut of the tree and withdrawal from the tree while the second blade cuts through the tree so that the first and second blades together make a complete cut of the body of the tree.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to tree shear apparatus, and more particularly, to a tree shear apparatus which incorporates a pair of blades, one of which cuts a portion of and withdraws from the body of a tree. 
     In the shearing of a tree by conventional tree-shearing apparatus, it is well known to provide a single blade which cuts entirely through the body of a tree toward an anvil in contact with the tree. While such a tree-shearing apparatus has been found relatively effective in operation, it has been found that a certain amount of tearing and splintering of the tree takes place as the blade approaches the anvil as the cut is almost complete. Such damage is, of course, highly undesirable, resulting in a certain amount of wood which cannot be used for desired purposes. 
     SUMMARY OF THE INVENTION 
     It is accordingly an object of this invention to provide tree shear apparatus which provides an efficient cutting of the body of the tree while minimizing splitting of any portion thereof. 
     It is a further object of this invention to provide tree shear apparatus which, while fulfilling the above object, is extremely simple in design and effective in use. 
     It is a still further object of this invention to provide a method of shearing the body of a tree which insures that minimal tearing or splintering of the body of the tree takes place. 
     Broadly stated, the tree-cutting apparatus comprises frame means, a first blade movably mounted relative to the frame means, and a second blade movably mounted relative to the frame means, the body of a tree being positionable between the first and second blades. Means are operatively connected with the blades for moving the first and second blades into and cutting the body of a tree, and for providing at least a partial withdrawal of the first blade upon the first blade having made a partial cut of the body of a tree, and for providing that the second blade continues cutting of the body of a tree subsequent to the cutting action of the first blade. 
     Broadly stated, the method of cutting the body of a tree comprises moving a first blade into engagement with and through a portion of the body of a tree to define a cut of a given depth, moving a second blade into engagement with and through a portion of the body of the tree to define a cut, the first blade being withdrawn so that the cut of the second blade provides, along with the cut of the first blade, a full cut of the body of a tree. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other objects of the invention will become apparent from a study of the following specification and drawings, in which: 
     FIG. 1 is a plan view, with portions removed, of the tree shear apparatus embodying the invention, wherein the blades are in their open positions; 
     FIG. 2 is a view similar to that shown in FIG. 1, but with the blades in an intermediate position; and 
     FIG. 3 is a view similar to that shown in FIG. 1 and FIG. 2, but with the body of the tree being fully cut therethrough. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Shown in FIGS. 1, 2 and 3 is the shear apparatus 10, which may be fitted to the front portion of a vehicle as is well known, such front portion including, for example, grapple arms, to grip the body or trunk of the tree as the shearing is taking place. 
     As shown in FIGS. 1-3, the shear apparatus 10 includes a frame 12 which in turn includes a generally U-shaped recess 14, the frame 12 being positionable so that the body 16 of a tree may seat within the recess 14. A first blade 18 is pivotally mounted relative to the frame 12 on one side of the recess 14, and a second blade 20 is pivotally mounted to the frame 12 on the other side of the recess 14. The blades 18,20 have cutting edges 22,24 as shown. A bell-crank 26 has its mid portion pivotally connected to the frame 12 at 28. A first link 30 has one end pivotally connected to one end of the bell-crank 26 at 32., and the other end pivotally connected to the blade 18 at 34. A second link 36 has one end pivotally connected to the other end of the bell-crank 26, and the other end of the link 36 is pivotally connected to the blade 20. A hydraulic cylinder 38 has its head end 40 pivotally connected to the frame 12, and its rod end 42 pivotally connected to the blade 20. 
     In the use of the apparatus, the vehicle is moved so that the body 16 of a tree is positioned in the recess 14, with the cylinder 38 fully retracted as shown in FIG. 1, so that the body 16 of the tree is positioned between the blades 18,20. Extension of the cylinder 38 pivots the blade 20 to move the edge 24 into engagement with the body 16, further extension of the cylinder 38 causing the blade 20 to cut through a portion of the body 16 of the tree. During such time, the link 36 is being moved through movement of the blade 20 to pivot the bell-crank 26 in a counterclockwise direction. Such movement of the bell-crank 26 moves the pivotal connection 32 of the bell-crank 26 and first link 30 from one side to the other of a straight line connection (i) the pivotal connection 28 of the bell-crank 26 and frame 12 and (ii) the pivotal connection 34 of the first link 30 and blade 18. That is, counterclockwise movement of the bell-crank 26 provides that the blade 18 is moved into engagement with and through a portion of the body 16 of the tree to define a partial cut of the body 16 of the tree of a given depth, determined by the pivots 28,32,34 falling along a straight line (FIG. 2). Further counterclockwise movement of the bell-crank 26 provides withdrawal of the blade 18 from the body 16 of the tree. 
     As set forth above, such counterclockwise pivoting of the bell-crank 16 is provided by continued extension of the cylinder 38, which is also moving the blade 20 through a portion of the body 16 of the tree to define a cut, the blades 18,20 actually making their initial cuts simultaneously. 
     As the blade 18 is being withdrawn, the cutting action of the blade 20 continues, the blades 18,20 being in the same plane so that as the cut of the blade 20 reaches the cut of the blade 18, from which the blade 18 has already withdrawn, a complete cut is provided through the body 16 of the tree. 
     The movement of the blade 18 is chosen to provide that the partial cut thereby is substantially less than a full cut of the body 16 of the tree. For example, if the body 16 of the tree is of the order of 18 inches in diameter, the full depth of cut of the blade 18 may be with advantage, from 2 to 4 inches.