Abstract:
The tree harvesting apparatus and method of this invention are particularly useful in congested areas where the range of equipment movement is limited and where unrestrained heavy tree bolts would cause damage to surrounding property if allowed to free fall to the ground. The subject apparatus is adapted to engage and sever large tree limbs, tree tops and tree bolts from free standing trees by means of tree gripping and severing means which is operable to form a kerf without becoming bound within the same. Further, the subject apparatus is adapted to weigh a tree bolt or tree top immediately upon its formation and while in juxtaposition with the free standing tree.

Description:
FIELD OF THE INVENTION 
     This invention relates to a tree harvesting apparatus and method and, more particularly, to an improved tree severing mechanism which includes an anti-binding tree cutting means and a tree bolt weighing means. 
     BACKGROUND OF THE INVENTION 
     This invention is an improvement on this inventor&#39;s prior U.S. Pat. No. 7,086,435 B1. Also, other teachings of tree harvesting, cutting and gripping apparatus mounted on the end of an adjustable boom are illustrated in U.S. Pat. Nos. 6,408,906 B1; 3,532,141; 3,536,113; 4,269,241 and 6,123,124. 
     For some years, tree severing mechanisms or felling heads have been mounted on the end of extendable booms which are operable from a motorized vehicle, something similar to a “cherry picker”. These vehicles are maneuverable and can negotiate in very limited space. These manipulated felling heads cause much less damage to the surrounding environment or structures. The felled tree bolts are not allowed to drop to the ground or be dragged along the forest floor, crushing and uprooting young saplings, much less being allowed to flatten someone&#39;s dwelling. 
     The first tree harvesters merely severed the tree at its base and allowed it to fall without thought as to direction or damage. Then, loggers began to ascend trees delimbing as they went. Direction to tree fall was supplied by tying a rope or line to the top of the tree and pulling the same by hand or tractor in a preferred direction while being severed at the tree base. The third harvesting practice was the use of a crane supporting a platform for a tree climber wielding a chain saw to trim limbs and cut short tree bolts. 
     Most of today&#39;s tree harvesting of this type occurs in congested area, such as housing developments, where movement in confined areas is critical. Thus, the cut tree top or other cut tree bolts cannot be released and allowed to free fall to the ground and risk damaging structures, power lines and prized fruit trees. Therefore, the cut portion must be lowered to the ground while still in the grasp of the machine. Since trees vary in size and weight, risks are taken on some occasion when the actual weight of the cut portion of the tree is so heavy as to overload the boom and cause the entire mechanized unit to tip over. 
     The monitoring and measuring the weight of a fixed load on a boom end or forklift has been taught by U.S. Pat. Nos. 3,990,584; 3,993,166; 4,456,093 and 4,746,024 which are hereby incorporated by reference. In U.S. Pat. No. 7,086,435 B1, the inventor (who is the same as the subject inventor) taught a weighing means for a severed tree bolt which was an improvement over the art at that time but not accurate enough for some critical applications. The objection is that calculating the weight of an object on the end of an extended boom is affected by the rigidity of the extended boom, wind pressure acting on the boom and cut tree bolt section and the stability of the base machine platform from which it extends. Any bobbing up and down by the weighted object will cause fluctuations in the measurements which may already exceed the limits of reliability for safety purposes. Also, an over-the-limit weighing tree top or bolt once removed from the free standing tree could topple over the support vehicle and releasing the tree top once the toppling movement had begun would be too late to rectify the situation. 
     Of particular concern in the cutting of free standing trees or large limbs extending therefrom is the binding of the saw blade while passing through the tree forming the kerf, the kerf being the incision made in the tree by the saw blade. As the kerf is being formed, the tree due to gravity or a spring load within the tree itself will tend to close the kerf thus impinging upon the saw blade and preventing any further saw blade movement. Upon such an occurrence, moving parts such as the saw blade chain may shear and separate with considerable force. Thus, not only will the saw blade chain disintegrate sending out shrapnel in all directions endangering those around but also will completely interrupt and bring to a standstill all cutting operations. Those familiar with any woodworking operation is appreciative of the consequences resulting from the binding of a cutting saw blade while still in the kerf. 
     The motorized vehicle with the extendable boom is made by Manitou North America, Inc. of Waco, Tex., and is well known in the trade. The Manitou Model MRT 2150 and other similar devices incorporate a computerized system for measuring and displaying the weight of a load of construction material placed on a forklift mounted on the end of a boom. The turntable on which the boom of the Manitou apparatus is situated can rotate 360 degrees. The end of the boom upon which the subject tree severing mechanism is mounted can be lowered to essentially ground level or be raised to a height of at least 80 feet. The Manitou apparatus also has means for measuring and displaying the height at which the end of the boom is located and imputing that height as a signal to a computer. Further, this apparatus has means for measuring and displaying the horizontal distance between the center of the boom turntable and the projected location of the tree severing apparatus measured on the horizontal plane passing through the base of the boom. A signal representing this distance is also imputed to the Manitou apparatus computer as one factor in helping determine the likelihood of the Manitou apparatus tipping over when the boom end is at a particular height, angle and is carrying a particular load. 
     In the prior art, many different types of mechanisms have been used to create the side to side tilting motion of the felling head. Some systems use a pair of hydraulic actuators mounted on the felling head to achieve the tilting motion. However, these prior art arrangements tend to be bulky, heavy and expose certain moving part to the rigorous environment of the logging industry. 
     Thus, a principal object of this invention is to provide a tree harvesting apparatus and method for general use but particularly adapted for use in a crowded suburban or business area. This apparatus enables a tree top or cut log bolt being harvested to be gripped and weighed prior to being lowered or allowed to free fall to the ground. 
     Another primary object of this invention is to provide means for grasping a standing tree in a manner that will allow the cutting means, i.e., chain saw or rotation blade, to form a kerf in the tree that will not bind the cutting means. 
     Another object of this invention is to provide a tree cutting head mounted on an extending boom that is rotatable in both a plane being horizontal to the ground or base area and in a plane being perpendicular to the ground through a 180 degree arc in each plane. 
     Other objects and features of this invention will become apparent by reference to the following drawings and description. 
     SUMMARY OF THE INVENTION 
     According to this invention, a tree harvesting apparatus (and method) is provided with at least three sets of tree gripping arms and a tree cutting mechanism located between the middle and lower sets of gripping arms (counting from the top). This tree gripping and cutting mechanism sequentially cuts the tree tip and the log bolts as the mechanism descends down the tree stem. After each cut, beginning with the tree top, the mechanism which is mounted at the end of an extendable boom lowers the firmly grasped cut bolt to the ground in an orderly fashion. When the tree harvesting operation is being carried out in a congested area where the weight of the cut bolt could cause a tipping problem, this invention enables the tree bolt to be weighed virtually in situ after being cut and the measured weight is used as a basis for deciding whether to allow the bolt to free fall or be lowered to the ground. That is, if the bolt weight is excessive and could cause a vehicle tipping problem, the tree gripping arms are immediately released and the tree bolt falls harmlessly to the ground. Any decision to release the tree bolt when not being supported by the free standing tree stem would be too late for the vehicle tipping motion would already be in progress. 
     The weighing means of this invention requires that a kerf be formed in the free standing tree by the severing means (chain saw) while pairs of gripping arms engage the tree on both sides of the kerfs to prevent any movement by the tree. Once the kerf is formed in the tree, the tree&#39;s upper or cut bolt portion is suspended in space the width of the kerf above the uncut or free standing portion of the tree. The preferred embodiment provided two pairs of gripping arms to secure the cut portion or tree bolt. The use of only one pair of gripping arms in the area above the kerf could not restrain the cut bolt from reacting to a torque applied to the tree bolt from wind, gravity or some other means. While the cut bolt is suspended, the free standing tree and the cut tree bolt are securely in the grasp of the engaging pairs of gripping arms, i.e., the two upper pairs of gripping arms secure the cut bolt above the free standing tree the distance of the formed kerf while the lower pair of gripping arms securely grasp the free standing tree. A strain gauge is placed across the kerf and an accurate weight measurement is obtained while the cut bolt and free standing tree are still in alignment and while no external forces, such as wind, are allowed to act upon the total mechanism. 
     The tree gripping and severing mechanism which is mounted on the end of an extendable boom must be rotatable in two perpendicular planes to be effective. The rotation through the vertical plane is provided by a hydraulic piston and cylinder combination which is common in the art. However, the rotation of the gripping and severing mechanism about a horizontally aligned axis is not so easily achieved. Torque must be provided to the gripping and severing mechanism to rotate the same about an axis which is generally parallel to the ground. Such torque is provided by two sets of hydraulic systems, the first hydraulic system connecting the stationary post extending from the boom end to a rotatable cylinder attached to the stationary boom end by means of a first bearing and a second hydraulic systems having one end being attached to the rotatable cylinder and the other end being connected to the gripping and severing means mounting shaft. The gripping and severing means mounting shaft is rotatably mounted in the rotatable cylinder by means of a second bearing. In summary, the gripping and severing means mounting shaft may be rotated about the axis generally parallel to the ground through an arc of at least 180 degrees in order that the gripping means may grasp either the main tree trunk or any limb extending outwardly therefrom. This rotation is accomplished by having the first hydraulic system rotate the cylinder at least 90 degrees and by having the second hydraulic means rotate the gripping means mounting shaft an additional 90 degrees relative to the cylinder. Thus, by engaging sequentially the first and second hydraulic systems, the gripping and severing means mounting shaft is rotated 180 degrees relative to the stationary head. 
     An additional embodiment of this invention is shown in  FIG. 8 . With the lower pair of gripping arms firmly clutching the tree, the kerf is slightly opened by applying a lateral and pivoting motion to the tree bolt being cut and which is held by the middle and upper pairs of gripping arms. Such maneuver is accomplished by severing the backbone post at a location beneath the saw blade forming upper and lower backbone parts which are then joined by a pivot pin. This junction allows the two upper pairs of gripping arms to pivot relative the lower gripping arms and prevent the cut bolt from collapsing on the free standing tree and binding the saw blade. 
     Another advantage of this embodiment is that the pivot pin can be withdrawn to allow the lower gripping arms and lower backbone part to be removed from the apparatus. Thus, the last cut of the tree can be proximate ground level. Also, without the lower gripping arms being present, smaller tree limbs can be removed from the free standing tree prior to the tree tip and tree bolts being cut. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view illustrating the tree harvesting apparatus of this invention being mounted on the end of a telescoping boom extending outwardly from a land traversing vehicle and being clamped to the free standing tree preparatory to its top being cut. 
         FIG. 2  is a side enlarged view of the tree harvesting apparatus being attached to a free standing tree and in a position to cut a tree bolt. 
         FIG. 3  is a partial side elevation view of the tree harvesting apparatus showing the gripping arms securing both the cut bolt and the free standing tree to the mounting shaft. 
         FIG. 4  is an enlarged sectional view taken through a portion of the tree harvesting apparatus along the line  4 - 4  of  FIG. 2 . 
         FIG. 5  is an enlarged, plan view of a portion of the tree gripping apparatus. 
         FIG. 6  is a partial perspective view of the tree gripping and severing mechanism being rotatably connected to the bearing mounted on the stationary boom end with the gripping arms contracted. 
         FIG. 7  is a perspective view of the tree gripping and severing apparatus showing the gripping arms extended and showing the hydraulic means connected to the cylinder lever for rotating the gripping and severing means about an axis. 
         FIG. 8  is an elevation view of the tree gripping and severing mechanism showing the upper tree gripping arms grasping an irregular tree bolt and showing a lateral force being exerted on the tree bolt to maintain separation in the kerf. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With reference initially to  FIG. 1  and using the Manitou MRT 2150 as a model (other “cherry picker” crane type vehicles can be used), this invention incorporates a vehicle  10  having a cab  11  and extendable boom  12  mounted on turntable  13  which can rotate through an arc of 360 degrees. Turntable  13  is stabilized by means of adjustable outriggers  14  which are used to secure and level vehicle  10  prior to the use of boom  12 . While the end of boom  12  may be adaptable to receive other mechanisms, for example a conventional delimbing apparatus, its primary purpose in accordance with this invention is to receive tree gripping and severing mechanism  15 . 
     Tree gripping and severing mechanism  15  is attached to boom end  20  as well as post  21  is stationarily mounted. In other words, all working parts of tree gripping and severing mechanism  15  rotate about axis  22  which extends outwardly along a horizontal plane from boom end  20 . Extending along said axis  22  (see  FIG. 2 ) is multifaceted cylinder  23  rigidly attached to boom end  20  by means of anchor cylinder  24 . First cylinder bearing  25  is mounted on anchor cylinder  24  and is operable to rotate in a plane perpendicular to axis  22  and parallel to the front plane of boom end  20 . Rigidly united to first cylinder  25  is axially extending piston actuated cylinder  26 . Cylinder lever  27  is rigidly mounted on piston actuated cylinder  26  such that any movement imparted to cylinder lever  27  will result in a likewise movement in piston actuated cylinder  26 . Hydraulic piston-cylinder arrangement  28  is comprised of hydraulic piston  29  and hydraulic cylinder  30  which are respectively connected to post  21  by means of pin  31  and to cylinder lever  27  by rotatable coupling  32 . Thus, upon energizing first hydraulic piston-cylinder arrangement  28 , hydraulic piston  29  is either forced into or out of hydraulic cylinder  30  causing cylinder lever  27  and multifaceted cylinder  23  to rotate about axis  22 . By energizing hydraulic piston  29 , cylinder lever  27  and, correspondingly, piston actuated cylinder  26  are rotated about axis  22  at least 90 degrees. Thus, tree gripping and severing mechanism  15  (its functions to be fully described hereinafter) is rotated about axis  22  without the activation of any other mechanism. 
     Tree gripping and severing mechanism  15  (also see  FIG. 4 ) is rotated about axis  22  an additional 90 degrees by means of second cylindrical bearing  35  connecting anchor cylinder  24  with tree gripping and severing head  36  by means of shaft  37 . Torque to rotate tree gripping and severing head  36  about axis  22  is provided by second piston-cylinder arrangement  38 . Said arrangement  38  is comprised of second hydraulic cylinder  39  and second hydraulic piston  40  with said second hydraulic piston  40  being rotatably connected to cylinder lever  27  by small shaft  41  and said hydraulic cylinder  39  being connected to head plate  42  by means of pin  43 . Thus, as piston  40  slides in and out of hydraulic cylinder  39 , tree gripping and severing mechanism  15  is rotated about axis  22  by means of second hydraulic bearing  35 . 
     The 180 degree rotation of tree gripping and severing mechanism  15  can best be described as a two part system although both parts may act in tandem. Assuming that tree gripping and severing mechanism  15  is in a vertical position as shown in solid lines in  FIG. 4 , said mechanism  15  can be rotated clock-wise by the extension of hydraulic piston  29  from said hydraulic cylinder  30  to Position A (shown in dotted lines having hydraulic piston  29 ′, hydraulic cylinder  30 ′ and head plate  42 ′ to assume a new position about axis  22 ). In this scenario, piston  40 ″ does not change its position relative to cylinder  39 ′. To push base plate  42  counter-wise to Position B, piston  40  is withdrawn into cylinder  39  thus moving base plate  42  through an arc about axis  22  to a new position. Shown in dotted lines in  FIG. 4 , piston  40 ″ has been withdrawn by hydraulic means into cylinder  39 ″. By actuating the hydraulic means of this two part system, base plate  42  and its attached tree gripping and severing mechanism  15  is rotated through an arc of 180 degrees about axis  22 . 
     In reference to  FIGS. 2 ,  3 ,  5  and  6 , the relative parts and operation of tree gripping and severing mechanism  15  will be described. Structural integrity of the tree gripping and severing mechanism  15  is provided by backbone post  50  which is attached to said boom end  20  by means of head plate  42  and shaft  37  which is an integral part of multifaceted cylinder  23 . An essential part of this invention is the construction and action of the pairs of tree gripping arms  52  and  52 ′,  53  and  53  and  54  and  54 ′. Backbone post  50  is comprised of main support post  55  and tilting post  56  which is rotatably connected to main support post  55  by means of pin  57 . All gripping arms  52 ,  52 ′,  53 ,  53 ′ and  54 ,  54 ′ are either mounted on main support post  55  or tilting post  56  and their operation which is common to all gripping means is shown in  FIG. 5 . 
     In reference to  FIGS. 5 and 7 , tilting post  56  supports pincer mechanism  58  which includes gripping arms  52 ,  52 ′ working on pivot pins  60  and  61  to engage free standing tree  9 . Gripping arms  52 ,  52 ′ are actuated by hydraulic cylinders  62  and  63 , respectively, which have selected pistons  64  and  65  rotatably connected to tilting post  56  by means of pin  66 . Pistons  64  and  65  are, in turn, connected to gripping arms  52 ,  52 ′ by means of pins  67  and  68 . Thus, upon the activation of hydraulic cylinders  62  and  63 , pistons  64  and  65  respectively exert pressure on pins  67  and  68  which cause gripping arms  52 ,  52 ′ to rotate about pivot pins  60  and  61 , respectively, and force gripping arms  52 ,  52 ′ inwardly into tree  9 . Gripping arms  52 ,  52 ′ engage and power tree  9  into beveled restraining plate  70  such that beveled edge  71  thereof slightly penetrates free standing tree  9  to the extent that cut tree bolt  72  cannot slip while being clinched by gripping arms  52  ( 52 ′). In practice, the three pincer mechanisms  58  operate in the same manner and are comprised of spaced apart beveled restraining plates  70  and  70 ′ and gripping arms  52  and  52 ′ which are rotatably mounted between said beveled restraining plates  70  and  70 ′ to force said tree bolt into a binding relationship with said beveled restraining plates  70  and  70 ′. 
     The means for cutting free standing tree  9  into tree bolts  72  is of prime importance and is the ultimate object of this invention. Such cutting cannot be accomplished if saw blade  75  becomes bound in kerfs  76  while forming the same. In a normal logging operation, gravity and other forces may act on tree bolt  72  to impinge it onto saw blade  75  causing it to become bound within kerfs  76 . In this invention, upper gripping arms  52 ,  52 ′ clamp upon the upper section of tree bolt  72  while middle gripping arms  53 ,  53 ′ firmly clamp upon the lower section of tree bolt  72 . Simultaneously therewith, lower gripping arms  54 ,  54 ′ securely engage free standing tree  9 . Thus, prior to saw blade  75  passing through free standing tree  9  forming kerfs  76  and tree bolt  72 , free standing tree  9  and tree bolt  72  were one and the same. With the various gripping arms securely clutching free standing tree  9  against backbone post  50 , no movement of tree bolt  72  relative backbone post  50  or free standing tree  9  is possible upon saw blade  75  being passed through free standing tree  9  forming kerfs  76  and tree bolt  72 . 
     Regardless if how tightly tree bolt  72  is clasped by the cooperating gripping arms, kerfs  76  will tend to close slightly after its formation and prevent a safe withdrawal of saw blade  75  from kerf  76 . To provide for a nonbinding retraction of saw blade  75 , tension inducing spring  77  is stretched across junction pin  57  and is attached by any means to tilting post  56  and backbone post  50 , respectively. Thus, tension spring  77  minutely increases the width of kerf  76  to provide for an easy egress of saw blade  75  from kerf  76 . 
     Having separated tree bolt  72  from free standing tree  9  by means of saw blade  75 , tree bolt  72  (a tree top if that cut is the first cut) is weighed immediately by means of strain  79 , the input signals of which being relayed to a computer (not shown) located on vehicle  10 . If the weight of bolt  72  (or tree top) exceeds a prescribed limit, tree bolt  72  is released by Gripping arms  52 ,  52 ′ and  53 ,  53 ′ and allowed to free fall to the ground. If it is determined that tree bolt  72  has a dangerous weight at some location away from free standing tree  9  as taught by the prior art, the damage has already been done for the vehicle operator has no choice but to drop the tree bolt or tree top instantly or risk injury to himself and his vehicle. Thus, if the tree bolt happens to be above a dwelling or vehicles, the falling tree bolt will cause damage to whatever object lies in the drop zone beneath. 
     With reference to  FIG. 8 , an alternative kerf  76  maintaining mechanism is shown. The basic structure of tree gripping and severing mechanism  15  remains the same. All gripping arms  52 ,  52 ′,  53 ,  53 ′,  54  and  54 ′ are mounted on their respective sections of backbone post  50 . In this embodiment, backbone post  50  is comprised of tilting post  56  which is rotatably connected to main support post  55  by means of pin  57 . The lower end of main support post  55  has been bifurcated to form swinging post  80  which is joined to main support post  55  by means of spring loaded shaft  81 . Swing post  80  is free to oscillate about spring loaded shaft  81  when being lifted into position to engage free standing tree  9 . To avoid unwanted movement during transportation from job to job, swinging post  80  is provided with lock pin  83  which is adapted to be removed prior to mounting tree gripping and severing mechanism  15  on free standing tree  9 . 
     Gripping arms  54  and  54 ′ are adapted to engage and force free standing tree  9  against swinging post  80  and into an immoveable position such that neither swinging post  80  not free standing tree  9  can move relative each other. At this stage, kerf  76  had yet to be formed and free standing tree  9  is a single and continuous entity throughout its length. Next, gripping arms  53  and  53 ′ are actuated to engage and force free standing tree  9  against main support post  55  in a binding relationship. Lastly, tilting post  56  which is mounted on main support post  55  by means of pin  57  engages and squeezes free standing tree  9  against itself by means of gripping arms  52  and  52 ′ regardless of the curvature of free standing tree  9 . Thus, pincer mechanism  58  which includes tilting post  56  and attachments is adapted to rotate through arc X-X to accommodate any deformity in free standing tree  9 . After securing gripping arms  52  through  54 ′ about free standing tree  9 , saw blade  75 , which is mounted on main support post  55  above spring loaded shaft  81 , is activated to cut a kerf  76  in free standing tree  9  thereby forming curved tree bolt  82 . 
     Simultaneously with the passing of saw blade  75  through free standing tree  9 , tree gripping and severing mechanism  15 , which is connected to main support post  55  by means of shaft  37 , is tilted slightly through arc Y-Y to maintain kerf  76  in an open and nonbinding position as saw blade  75  cuts through free standing tree  9  to form curved tree bolt  82 . In summary, kerf  76  is maintained in a nonbinding position by pivoting main support post  55  slightly about spring loaded shaft  81  while swinging post  80  is maintained in a rigid position against free standing tree  9  by gripping arms  54  and  54 ′. 
     Harvesting a free standing tree according to this invention is normally preceded by stabilizing and leveling vehicle  10  by means of outriggers  14  followed by the delimbing of the tree by any common method. The steps of stabilizing and delimbing are followed by the steps of the method of this invention described as follows: 
     Step 1. Mounting a tree gripping and severing means to the free end of a telescoping boom extending outwardly from a vehicle. 
     Step 2. Rotating the tree gripping and severing means about an axis perpendicular to the boom end to place the tree gripping and severing means in alignment with the stem of the free standing tree. 
     Step 3. Attaching the tree gripping and severing means to a free standing tree at a desired location by means of upper, middle and lower pairs of axially aligned gripping arms. 
     Step 4. Securing the tree gripping and severing means to the free standing tree by activating the upper, middle and lower pairs of gripping arms to grasp the tree in a pincer like manner. 
     Step 5. Sculpturing a cut tree bolt from the free standing tree by passing a tree severing means through the free standing tree along a plane being perpendicular to that plane defined by the gripping arms and between the middle and lower pairs of gripping arms to form a kerf in the tree. 
     Step 6. Maintaining the kerf as defined by the cut tree bolt and the free standing tree. 
     Step 7. Weighing the cut tree bolt while being held by the upper and middle pairs of gripping arms and while the free standing tree being held by the lower pair of gripping arms in an immobile relationship. 
     The apparatus and method of this invention can be seen to be both versatile and adaptable to those situations in which weighing is required and necessary because of safety concerns.