Abstract:
An excavating machine, representatively a tracked excavator, has a boom stick portion on which an excavating bucket and a gripper assembly mounted. A hydraulic breaker is protectively mounted inside the breaker assembly and extends outward therefrom. The bucket may be operated independently of the gripper assembly for digging operations. The gripper assembly may be positioned independently of the bucket and the breaker actuated for refusal material-breaking operations. The bucket and the gripper may be cooperatively operated to perform removal operations. The same excavating machine can be used for digging, gripping, and breaking operations without a tool change.

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention generally relates to a material handling apparatus and, in an embodiment thereof, more particularly relates to an excavating apparatus, representatively a tracked excavator, having operatively attached to the stick portion of its boom a specially designed combination bucket, breaker, and gripping apparatus which uniquely permits the excavator operator to selectively carry out multiple operations, including digging, breaking refusal material, and object grip and lift tasks without having to change out equipment on the stick. 
     2. Description of Related Art 
     Large scale earth excavation operations are typically performed using a powered excavating apparatus, such as a tracked excavator, having an articulated, hydraulically pivotable boom structure with an elongated, pivotal outer end portion commonly referred to as a “stick”. Secured to the outer end of the stick is an excavating bucket, which is hydraulically pivotable relative to the stick between “closed” and “open” positions. By pivotally manipulating the stick, with the bucket swung to a selected operating position, the excavator operator uses the bucket to forcibly dig into the ground, scoop up a quantity of dirt, and move the scooped up dirt quantity to another location, such as into the bed of an appropriately positioned dump truck. 
     A first common occurrence during conventional digging operations is that the bucket strikes refusal material (in excavation parlance, a material which “refuses” to be dug up) such as rock which simply cannot be broken and scooped up by the bucket. When this occurs, it is typical practice to stop the digging operation, remove the bucket from the stick, and install a hydraulically operated “breaker” on the outer end of the stick in place of the removed bucket. The breaker has, on its outer end, an oscillating tool portion which rapidly hammers the refusal material in a manner breaking it up into portions which can be subsequently dug up. After the breaker has been utilized to break up the refusal material, the operator removes the breaker from the stick, replaces the breaker with the previously removed bucket, and resumes the digging operation with the bucket. 
     While this procedure is easy to describe, it is a difficult, laborious and time-consuming task for the operator to actually carry out due to the great size and weight of both the bucket and breaker which must be attached to and then removed from the stick, and the necessity for the operator to climb into and out of the high cab area of the excavator (often in inclement weather) to effect each bucket and breaker changeout on the stick. This sequence of bucket/breaker/bucket changeout, of course, must be laboriously repeated each time a significant refusal area is encountered in the overall digging process. 
     A previously utilized alternative to this single excavator sequence is to provide two excavators for each digging project—one excavator having a bucket attached to its boom stick, and the second excavator having a breaker attached to its boom stick. When the bucket-equipped excavator encounters refusal material during the digging process, it is moved away from the digging site, and the operator climbs down from the bucket-equipped excavator, walks over to and climbs up into the breaker-equipped excavator, drives the breaker-equipped excavator to the digging site, and breaks up the encountered refusal material. Reversing the process, the operator then switches to the bucket-equipped excavator and resumes the digging process to scoop up the now broken-up refusal material. 
     While this digging/breaking technique is easier on the operator, it is necessary to dedicate two large and costly excavators to a given digging task, thereby substantially increasing the total cost of a given excavation. A modification of this technique is to use two operators one to operate the bucket-equipped excavator, and one to operate the breaker-equipped excavator. This, of course, undesirably increases both the manpower and equipment cost for a given excavation project. 
     A second common occurrence during conventional digging operations is that removal objects (objects that need to be “removed” or relocated), such as large surface rocks, felled trees, construction debris, and other objects that do not fit into the bucket, need to be removed. When this occurs, it is typical practice to use a specialized excavator that is equipped with a static or hydraulically operated “thumb.” The bucket can be used to position the removal object between the bucket and the thumb for gripping the removal object, lifting and relocating it. 
     An additional limitation to this configuration is that if the excavator is fitted with a conventional thumb, the thumb presents a second obstacle to the attachment of the breaker. In this instance, a second excavator having a breaker attached to its boom stick is more appropriately required for the digging project. When the bucket and thumb-equipped excavator encounters refusal material during the digging process, it is moved away from the digging site, and the operator climbs down from the bucket-equipped excavator, walks over to and climbs up into the breaker-equipped excavator, drives the breaker-equipped excavator to the digging site, and breaks up the encountered refusal material. Reversing the process, the operator then switches to the bucket and thumb-equipped excavator and resumes the digging process to scoop up the now broken-up refusal material. 
     Once again, it is necessary to dedicate two large and costly excavators to a given digging task, thereby substantially increasing the total cost of a given excavation project. 
     An attempt to solve this problem is disclosed in U.S. Pat. No. 6,085,446 and U.S. Pat. No. 4,100,688 for an excavating machine having a motorized milling tool attached to the back of the bucket. A primary disadvantage of these devices is complexity, cost, and reliability. Another disadvantage is the weight that must be continuously carried by the bucket. The additional weight substantially reduces the carrying capacity and mobility of the bucket. Another disadvantage to the device of U.S. Pat. No. 6,085,446 is that the back of the bucket cannot be used to smooth or pad the soil, as is a well-known practice in the industry. Another disadvantage is that surface rock is not subject to an overburden pressure, so it generally fails faster under compression and impact forces than by the shearing forces of a scrapping and gouging rotary drilling tool. 
     Another attempt to solve this problem is disclosed in U.S. Pat. No. 4,070,772 for an excavating machine having a hydraulic breaker housed inside, or on top of, the boom stick. A primary disadvantage of this device is that it is extremely complex and expensive. Another disadvantage of this device is that it cannot be retrofit to existing excavators. Another disadvantage of this device is that the size of the breaker is limited. Another disadvantage of this device is that the bucket must be fully stowed to access the breaker and vice versa, making simultaneous operation impractical. 
     A more recent attempt to solve this problem is disclosed in U.S. Pat. No. 5,689,905 for another excavating machine having a hydraulic breaker housed inside, or on top of, the boom stick. In this device, the cutting tool portion (such as a chisel) of the breaker is removed when not in use. A primary disadvantage of this device is that it fails to permit immediate, unassisted switching from breaker to bucket, and thus simultaneous operation is impossible. Another disadvantage of this device is that it requires manual handling of the extremely heavy chisel tool each time the operator desires to convert to a breaker or bucket operation. Another disadvantage of this device is that it is extremely complex and expensive. Another disadvantage of this device is that it cannot be retrofit to existing excavators. 
     More recently, a commercially successful solution to at least part of this problem is disclosed in U.S. Pat. No. 6,430,849, U.S. Pat. No. 6,751,896, U.S. Pat. No. 7,117,618 and U.S. Pat. No. 7,257,910 (collectively, “the &#39;849 patent family”). The &#39;849 patent family discloses the Bayonet® Breaker System which provides an excavating machine known as a back-hoe with a specially designed pivotable boom stick assembly that includes a boom stick having first and second excavating tools secured thereto for movement relative to the boom stick. The first excavating tool is an excavating bucket secured to the boom stick for pivotal movement relative thereto between a first position and a second position, and the second tool is a breaker secured to the boom stick for pivotal movement relative thereto between a stowed position and an operative position. 
     As described in the &#39;849 patent family, the bucket is operable when the breaker is in its stowed position. The bucket is movable by the drive apparatus independent of the breaker, to perform a digging operation. The breaker is operable when the bucket is in a first “stowed” position, which is away from the deployed position of the breaker to prevent contact and interference. The breaker is movable by the drive apparatus independent of the bucket, to perform a breaking operation. Accordingly, the excavating machine may be advantageously utilized to perform both digging and breaking operations without equipment change-out on the boom stick. 
     However, this solution fails to solve the need for gripping removal objects. Central to the inventions of the &#39;849 patent family is the avoidance of contact and interference of the bucket and the breaker during operation, the independence of their function and operation, and the remote positions provided for allowing independent operation. This is necessary because operating the bucket against the breaker is well-known in the industry to destroy the breaker housing and/or the breaker deployment cylinder. 
     Another disadvantage is that the &#39;849 patents disclose a hydraulic control circuitry operable to selectively route hydraulic fluid through the hydraulic flow circuit to (1) a first portion of the drive apparatus associated with the bucket, or (2) a second portion of the drive apparatus associated with the breaker. This may prevent interference of the bucket with the breaker, but it is undesirable for a gripping function that benefits from simultaneous operation of the breaker deployment cylinder and the bucket. 
     The &#39;618 patent suggests using the bucket against a free swinging and unpowered breaker for the purpose of lifting the breaker from a gravity deployed position back into a latched stowed position. This cylinder-less low cost alternative is now known to be unworkable as contact with even an unpowered breaker assembly destroys the breaker housing, and none have ever been made. Further, it is universally found necessary to have independent control over positioning of the breaker. Thus all workable configurations require a lower powered breaker deployment cylinder that is subject to destruction from the crushing force of the much higher powered hydraulic cylinder of the bucket. 
     The present invention contradicts the core principals of the prior art and practice by providing a combined bucket-gripper-breaker assembly on the end of an otherwise conventional excavator. In this invention, a gripper assembly is constructed around the breaker. The hydraulically powered gripper is then operated in concert with the bucket, intentionally placing the hydraulic power of the bucket and gripper assembly into operable positions of conflict. The reinforced structure of the gripper assembly is not damaged by the force. The gripper&#39;s serrated edges grip the removal object. To prevent overload and destruction of the gripper assembly deployment cylinder, a relief valve and accumulator are provided in the gripper&#39;s actuator line. Overloading by the bucket activates the relief valve, allowing hydraulic fluid to pass to the accumulator and causing retraction of the gripper, but avoiding destruction of the cylinder. In this manner, the additional functionality of gripping and lifting is provided to the excavating machine. This permits the use of the excavator to grip and lift material excavated by the breaker and bucket that might otherwise be unmovable or difficult to move with the bucket alone. 
     SUMMARY OF THE INVENTION 
     In carrying out principles of the present invention, in accordance with one embodiment thereof, an excavating machine, representatively a tracked excavator, is provided with a specially designed pivotable boom stick assembly that includes a boom stick having first, second, and third excavating tools secured thereto for movement relative to the boom stick. Illustratively, the first excavating tool is an excavating bucket secured to the boom stick for pivotal movement relative thereto between a first position and a second position, and the second tool is a gripper secured to the underside of the boom stick for pivotal movement relative thereto between a stowed position and an operative position. The third tool is a breaker secured inside the housing of the gripper and extending therefrom. 
     The bucket, when the breaker is in its stowed position, is movable by the drive apparatus to the second bucket position and is useable in conjunction with the boom stick, and independently of the breaker, to perform a digging operation. The breaker, when the bucket is in its first position, is movable by the drive apparatus to the breaker&#39;s operative position and is useable in conjunction with the boom stick, and independently of the bucket, to perform a breaking operation. 
     Accordingly, the excavating machine may be advantageously utilized to perform digging, gripping, and breaking operations without equipment changeout on the boom stick. 
     In one embodiment of the present invention, a boom stick assembly for use on an excavating machine is provided comprising a boom stick having a lower end, a top side, and an underside. A bucket is secured to a lower end of the boom stick for pivotal movement relative thereto. A gripper is pivotally connected to the lower end and underside of the boom stick for pivotal movement relative thereto. A breaker is located inside the gripper with its chisel extending outward from it. The bucket is movable between an extended position and a retracted position to perform a digging operation or a gripping operation. The gripper is movable between an extended position and a retracted position to perform a gripping operation in cooperation with the bucket. The gripper is extendable and retractable to position the breaker in relationship to refusal material targeted for breaking. 
     The breaker is hydraulically operable to perform a breaking operation. A first hydraulic cylinder is attached to the topside of the boom stick, and is operable to control movement of the bucket independent of the breaker assembly. A second hydraulic cylinder is attached to the underside of the boom stick, and is operable to control movement of the gripper independent of the bucket. A relief valve and accumulator are connected to the second hydraulic cylinder to permit compression of the second cylinder when the second cylinder is subjected to compressive force transferred from the first hydraulic cylinder that exceed a limit of the relief valve. 
     In another embodiment, the gripper further comprises a mounting plate attachable to an underside of the boom stick. A latch is affixed to the mounting plate. A housing assembly is pivotally connected to the mounting plate and has a boom side and an off-boom side. A gripper engagement structure is provided on the off-boom side of the housing. A strike is mounted to the boom side of the housing and is engagable with the latch for securing the gripper in a retracted position next to the boom stick. The hydraulically operable breaker is secured inside the housing and extends beyond the breaker. 
     In another embodiment, the first and second hydraulic cylinders are operable simultaneously. In another embodiment, the engagement surfaces extend to the pivotal connection of the housing to the lower end of the boom stick. 
     In another embodiment, the engagement surface is made of a wear resistant hardened steel. In another embodiment, the engagement surface is made of a wear resistant material welded to the off-boom edge of the housing. 
     In another embodiment, a reinforcement plate is connected to the housing, and a secondary engagement surface is provided on the reinforcement plate. In another embodiment, retraction of the bucket by force applied by the first cylinder is resisted by an opposing force applied by the second cylinder. In another embodiment, the excavating machine is a tracked excavator. 
     The advantage of the disclosed embodiments is that they provide additional and critical utility to a single excavating machine. Specifically, the excavator operator may uniquely and selectively carry out multiple operations, including digging, breaking refusal material, and object grip and lift tasks without having to change out equipment on the stick, and without the need for a second excavating machine. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a simplified, side view of a representative excavating machine having a bucket, gripper, and breaker combination, illustrating the variable positioning available for a bucket while the gripper and breaker are in the stowed position. 
         FIG. 2  is view of the excavating machine of  FIG. 1 , illustrating the variable positioning of the gripper and breaker while the bucket is in the stowed position. 
         FIG. 3  is view of the excavating machine of  FIGS. 1 and 2 , illustrating use of the gripper and bucket to grip and relocate a removal object (rock). 
         FIG. 4  is a side view of an embodiment of the gripper and breaker assembly. 
         FIG. 5  is an exploded view of an embodiment of the gripper and breaker assembly of the present invention. 
         FIG. 6  is an isometric view of one side of the gripper housing in accordance with an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Refer now to the drawings wherein depicted elements are, for the sake of clarity, not necessarily shown to scale and wherein like or similar elements are designated by the same reference numeral through the several views. 
     Referring to  FIGS. 1 and 2 , a tracked-excavator  10  in accordance with an embodiment of the present invention is disclosed. Excavator  10  has a boom stick  200 , which has a lower end  202 , a topside  204 , and an underside  206 . A bucket  300  is pivotally mounted on boom stick  200  at the lower end  202 . A first hydraulic cylinder  210  is pivotally attached at one end to the topside  204  of boom stick  200 . First hydraulic cylinder  210  or other actuator is pivotally connected at its other end to bucket  300  to cause bucket  300  to move between a retracted position  300   a  and an extended position  300   b  as shown by arrow in  FIG. 1 . 
     A gripper assembly  100  is pivotally mounted to underside  206  of lower end  202  of boom stick  200 . In the illustrated embodiment, gripper assembly  100  is pivotally attached to a first pivot  102  on a bracket  140 . In one embodiment, first pivot  102  is a bifurcated pivot. A second hydraulic cylinder  110  or other actuator is pivotally attached at one end to second pivot  104  on bracket  140 . Second cylinder  110  is pivotally attached at its other end to a third pivot  106  on gripper assembly  100 . In the illustrated embodiment, the distance between first pivot  102  and second pivot  104  is advantageously less than the distance between first pivot  102  and third pivot  106 . 
     A relief valve and accumulator (not shown) are connected to second cylinder  110  to permit compression of second cylinder  110  when second cylinder  110  is subjected to a compressive force that exceeds its limit. A latch  190  is located on underside  206  of boom stick  200 . When gripper assembly  100  is in a retracted or stowed position  100   a , latch  190  engages strike  132  (best seen in  FIG. 5 ) so that gripper assembly  100  remains in the retracted or stowed position. First cylinder  110  is used to move gripper assembly  100  between retracted position  100   a , a partially-extended position  100   b , a fully-extended position  100   c , or any position in-between as shown by arrows in  FIG. 2 . Gripper assembly  100  also includes a breaker  180 , which may be used to break apart any refusal material. Breaker  100  is mounted inside gripper assembly  100  where it is protected from contact with removal objects and contact with bucket  300 . A chisel of breaker  100  extends beyond gripper assembly  100 . 
     Referring to  FIG. 3 , the function capability of gripper assembly  100  in combination with bucket  300  is illustrated by their gripping a removal object  20  (e.g., tree stump shown). First cylinder  210  is activated to cause bucket  300  to move into the extend position and into direct contact against the removal object  20 . Second hydraulic cylinder  110  is also activated to cause gripper  100  to move into extended position  100   b  and into direct contact with the other side of removal object  20  and exerting force from the generally opposite direction as the force being applied by bucket  300 , thus gripping removal object  20 . First and second hydraulic cylinders  210  and  110  may be operated independently. In one embodiment, first and second hydraulic cylinders  210  and  110  may be operated simultaneously. Gripper assembly  100  includes a serrated or toothed surface (described below) for increasing friction between the gripper assembly  100  and any removal object  20  being gripped. Once gripped, removal object  20  can be relocated to another location. 
       FIG. 4  is an isometric view of an embodiment of a mounting system.  FIG. 4  illustrates bracket  140  and latch  190  of  FIG. 1  attached to a plate  225  by welding or other similarly secure means. In this embodiment, latch  190  can be located in proper alignment with bracket  140  and gripper assembly  100  on plate  225  prior to installation on excavating machine  10 . Plate  225  can then be attached to boom stick  200  in proper alignment as provided by alignment of plate  225  with underside  206  of boom stick  200 . Optionally, gripper assembly  100 , first cylinder  210  bracket  140  and latch  190  are mounted directly to underside  206  of boom stick  200  without use of plate  225 . Other embodiment options disclosed herein are independent of whether plate  225  is used or not, and the various embodiments of the invention are not dependent upon the attachment option illustrated in  FIG. 4 . 
     In the embodiments shown in  FIGS. 1-4 , bracket  140  is illustrated as attached to boom stick  200  (optionally by plate  225 ). One end of first cylinder  110  is pivotally coupled to bracket  140 . The opposite end of first cylinder  110  is pivotally coupled to third pivot  106  between a first body section  112  and a second body section  114  (not shown) of gripper assembly  100 . Body sections  112  and  114  pivotally couple gripper assembly  100  to first pivot  102 . First pivot  102  may be comprised of a pair of coaxial trunnions  160  located on bracket  140 . 
       FIG. 5  is an exploded view of an embodiment of gripper assembly  100 . Gripper assembly  100  provides a positioning means and protective structural surrounding for a reciprocating breaker  180 , also known as a hammer. Breaker  180  has a replaceable cutting tool  182  extending from one end, beyond gripper assembly  100 . A breaker end  184  is located on the end of breaker  180  opposite tool  182 . 
     In  FIG. 5 , body sections  112  and  114  are illustrated uncoupled. Engagement surfaces  117  are provided on the upper surface of body sections  112  and  114 . Engagement surfaces  117  may be comprised of serrations, or teeth, to enhance gripping. Engagement surfaces  117  may be made of wear resistant hardened steel or a wear resistant material. In one embodiment, engagement surfaces  117  are welded to the off-boom edge of body sections  112  and  114 . 
     A pair of reinforcement plates  119  is provided on the outside of each body section  112  and  114 . In the embodiment illustrated, reinforcement plates  119  have engagement surfaces  121  on their upper surfaces, extending to the engagement surfaces  117  on body sections  112  and  114 . Engagement surfaces  121  may be comprised of serrations, or teeth, which enhance gripping. Engagement surfaces  121  may be made of wear resistant hardened steel or a wear resistant material. In one embodiment, engagement surfaces  117  are welded to the off-boom edge of reinforcement plates  119 . 
     Reinforcement plates  119  act to strengthen gripper assembly  100  so as to resist torque and bending during gripping operations in which large and unbalanced compressive forces are placed on engagement surfaces  117  and  121 . Reinforcement plates  119  also protect breaker  180  from destructive contact with bucket  300  during gripping operations. 
     A hollow bushing  116  may be provided on each of body sections  112  and  114  for forming the pivot connection to bracket  140 . A series of aligned holes  118  are provided on body sections  112  and  114  and reinforcement plates  119  for assembly of gripper assembly  100 . In the illustrated embodiment, bolt protectors  120  are provided on the exterior of one of the reinforcement plates  119  (shown on the plate nearest to body section  112 ). 
     A pair of opposing lower lock plates  122  and a pair of upper lock plates  124  are provided for securing breaker  180  between body sections  112  and  114 . Aligned holes  118  are also located on lower lock plates  122  and upper lock plates  124 . Lock plates  122  and  124  are secured between breaker  180  and body sections  112  and  114  by nut and bolt assemblies  126  passing through holes  118 . In the embodiment, the nuts of nut and bolt assemblies  126  are of the acorn type. 
     A stop bar  128  is provided for bolted attachment between body sections  112  and  114  at aligned holes  118 . A pivot bar  130  is provided for bolted attachment between body sections  112  and  114  at aligned holes  118 . Third pivot  106  is comprised of pivot bar  130 . A strike  132  is provided for bolted attachment between body sections  112  and  114  at aligned holes  118 . 
     High strength materials may be used to fabricate body sections  112  and  114 , lower lock plates  122 , upper lock plates  124 , nut and bolt assemblies  126 , stop bar  128  and pivot bar  130  to strengthen gripper assembly  100  for gripping operations. 
       FIG. 6  is an isometric view of an embodiment of body sections  112  and  114  (showing only section  114 ) and reinforcement plate  119  in detail. In this embodiment, reinforcement plate  119  has counterbore holes  123 , which protect the heads of bolts  126  from destruction during gripping operations. 
     Having thus described the present invention by reference to certain of its embodiments, it is noted that the embodiments disclosed are illustrative rather than limiting in nature and that a wide range of variations, modifications, changes, and substitutions are contemplated in the foregoing disclosure and, in some instances, some features of the present invention may be employed without a corresponding use of the other features. Many such variations and modifications may be considered obvious and desirable by those skilled in the art based upon a review of the foregoing description of the embodiments. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention.