Abstract:
The present disclosure relates to a mounting arrangement for a cutting tooth for a trencher chain. The tooth includes a base portion aligned along a first plane. The base portion includes structure for allowing the cutting tooth to be connected to the trencher chain. The tooth also includes a distal portion that is generally obliquely aligned with respect to the first plane. A curved transition is located between the distal portion and the base portion. The curved transition curves away from the first plane and at least partially forms a cupped portion that is effective in the trenching operation. The base portion also includes a recess into which the mounting hardware can fit, to protect the mounting hardware from wear.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates generally to excavation machines. Specifically, the present invention relates to a mounting arrangement for cutting teeth for use with trencher chains.  
         BACKGROUND OF THE INVENTION  
         [0002]    Trenchers are conventionally used to dig lengths of trenches for laying underground pipe and cable. Most trenchers include a tractor unit equipped with an elongated boom. The boom is typically movable between a raised, generally horizontal position, and a lowered, substantially vertical position. The boom typically includes a cutting chain that is entrained about the boom. The chain generally includes exterior teeth or cutters for engaging the soil. Trenchers also commonly include a conveyer assembly for transporting the soil this is excavated by the chain.  
           [0003]    There are various types of cutting teeth or attachments that are commonly bolted to a trencher digging chain. Exemplary cutters are disclosed in U.S. Pat. No. 3,022,588 to Brown and U.S. Pat. No 6,154,987 to Rumer et al. Looking at the mounting arrangements disclosed in these two references: the &#39;588 reference discloses a cup cutter having a leading edge and a cupped portion for scooping loose material from a trench. The cup cutters are mounted on headed projections that extend from the side plates of the chain wherein the cutters have keyhole shaped openings that engage with the projections for securing the cutters to the chain. This design does not require the projections to be removed from the chain to repair the cutters. However, this design does not hold the cutters securely, the components are relatively delicate, and relatively expensive to manufacture. The &#39;987 reference discloses cutting teeth that are designed for cutting very compacted soils, gravel or rock and are mounted onto the digger chain by a more robust standard nut and bolt combination.  
           [0004]    Cutters, such as the cutters disclosed in the &#39;588 and &#39;987 patents, work effectively in a variety of digging conditions. The cup cutters disclosed in the &#39;588 patent work well in relatively soft soils while the cutters disclosed in the &#39;987 patent are intended for conditions wherein very abrasive materials are being trenched, including solid rock and loose rock conditions. In the harder digging conditions the cutters are subjected to higher loads and need to be mounted in a robust fashion. In those same conditions the cutters wear quickly and as a result the digging chain assembly needs frequent maintenance. The more robust mounting arrangement, as disclosed in the &#39;987 patent, subjects the mounting bolts to potential wear. This wear on the mounting hardware typically results in difficulties engaging a tool with the mounting hardware and as a result the chain assembly becomes difficult, time consuming and expensive to repair. Cutters used in the more demanding applications are typically mounted as shown in the &#39;987 patent and operators are confronted with the difficulty of properly maintaining them due to the wear of the mounting hardware.  
           [0005]    In these more demanding conditions the loads on the components of the chain assemblies increase and the structural integrity of those components becomes more critical. As a result the specific shapes and the material selected for the components becomes critical. During development and testing of this invention many different combinations of both shapes and materials were tested. A satisfactory combination has been identified, as set forth in the description that follows.  
         SUMMARY OF THE INVENTION  
         [0006]    One aspect of the present invention relates to a cutting tooth for a trencher chain. A cutting tooth includes a base portion aligned along a first plane. The base portion includes means for allowing the cutting tooth to be connected to the trencher chain. The cutting tooth further includes a pocket that cooperates with the mounting means, the pocket being located opposite from the first plane.  
           [0007]    Another aspect of the present invention relates to a trenching or digging chain assembly for use with a trencher. The chain assembly includes a plurality of sidebars aligned along a longitudinal centerline. The trencher chain also includes a plurality of rollers substantially permanently interconnecting the sidebars. The rollers are aligned along a lateral dimension that is transverse with respect to the longitudinal centerline. The chain further includes a plurality side mounting plates, these side mounting plates being substantially permanently interconnected with the rollers and sidebars. The chain further includes a plurality of cutting teeth that are fixedly mounted to the side mounting plates such that they can be removed for service. The cutting teeth include a physical feature that provides the mounting hardware with protection from wear that results from contact with the soils being excavated, yet does not interfere with installation tools required to secure the mounting hardware.  
           [0008]    A variety of advantages of the invention will be set forth in part in the description that follows, and in part will be apparent from the description, or may be learned by practicing the invention. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate several aspects of the invention and together with the description, serve to explain the principles of the invention. A brief description of the drawings is as follows:  
         [0010]    [0010]FIG. 1 shows a side view of a trencher;  
         [0011]    [0011]FIG. 2 shows a schematic diagram of the components of the trencher of FIG. 1;  
         [0012]    [0012]FIG. 3 shows a perspective view of a prior art trencher chain assembly;  
         [0013]    [0013]FIG. 4 shows a cross-section of the prior art chain assembly taken along line  4 - 4  of FIG. 3 with a cutting tooth mounted in a first position;  
         [0014]    [0014]FIG. 5 shows a cross-section of the prior art chain assembly taken along line  5 - 5  of FIG. 3 with a cutting tooth mounted in a second position;  
         [0015]    [0015]FIG. 6 shows a cross-section of the prior art chain assembly taken along line  6 - 6  of FIG. 3 with a cutting tooth mounted in a second position;  
         [0016]    [0016]FIG. 7 shows a perspective view of trencher chain assembly using the principles of the present invention;  
         [0017]    [0017]FIG. 8 shows a cross-section of a chain assembly taken along line  8 - 8  of FIG. 7 with a cutting tooth mounted in a first position;  
         [0018]    [0018]FIG. 9 shows a cross-section of a chain assembly taken along line  9 - 9  of FIG. 7 with a cutting tooth mounted in a second position;  
         [0019]    [0019]FIG. 10 shows a cross-section of a chain assembly taken along line  10 - 10  of FIG. 7 with a cutting tooth mounted in a third position;  
         [0020]    [0020]FIG. 11 shows a perspective view of a cutting tooth with the principles of the invention;  
         [0021]    [0021]FIG. 12 shows a perspective view of an alternative embodiment of a trencher chain assembly with the principles of the invention;  
         [0022]    [0022]FIG. 13 shows a side elevational view of an alternate embodiment of the cutting tooth; and  
         [0023]    [0023]FIG. 14 shows a side elevational view of an alternate embodiment of the cutting tooth  
         [0024]    [0024]FIG. 15 shows a perspective view of an alternate embodiment of the trencher chain assembly with cup cutters installed  
         [0025]    [0025]FIG. 16 shows a perspective view of a detailed drawing of the cup cutter with the principles of the invention;  
         [0026]    [0026]FIG. 17. shows a perspective view of a detailed drawing of an alternate cutter with the principles of the invention. 
     
    
     DETAILED DESCRIPTION  
       [0027]    Reference will now be made in detail to the prior art and to exemplary aspects of the present invention that are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.  
       Prior Art  
       [0028]    [0028]FIGS. 1 and 2 show an exemplary trencher  15 . The trencher  15  includes an engine  17  coupled to a right track drive  18  and a left track drive  20 , which together form a tractor portion  22  of the trencher  15 . A boom  24  is pivotally coupled to the tractor portion  22 . A digger chain  26  is mounted on the boom  24 . The chain  26  is driven around the boom  24  by a chain drive mechanism  23  powered by the engine  17 . The boom  24  is pivotally movable between a substantially horizontal transport configuration  25 , and a substantially vertical trenching configuration  27 .  
         [0029]    When maneuvering the trencher  15  around the work site, the boom  24  is maintained in the transport configuration  25  such that the chain  26  generally remains above the ground. To excavate a trench, the boom  24  is lowered toward the trenching configuration  27  and the chain  26  is driven around the boom  24 . When the chain  26  contacts the ground, cutting teeth of the chain  26  penetrate the ground and begin to excavate a trench. Once the boom  24  reaches the trenching configuration  27 , the tracks  18  and  20  are engaged causing the tractor  22  to creep forward. The chain  26  digs the trench and removes loose geologic material from the trench as the tractor  22  creeps forward.  
         [0030]    The trencher  15  is being disclosed exclusively for the purpose of illustrating an exemplary environment in which the various aspects of the present invention can be applied. It will be appreciated that the variety of trenchers are known in the art, and that the various aspects of the present invention can be applied or used in association with any type of trenching device.  
         [0031]    FIGS.  3 - 6  Illustrate a digging chain assembly  70  constructed in accordance with the prior art. The chain assembly  70  includes a base chain sub assembly that includes a plurality of rollers  74 , side bars  72 , side mounting plates  76 , and rivets  78 . The majority of these components are semi-permanently interconnected: the rivets  78  are typically upset or swaged such that the outer diameter of the portion extending through or beyond the side mounting plates  76  is bigger than the hole in the side mounting plates  76 . In this manner the rivets  78  are effectively connected to the side mounting plates  76 . Each chain assembly typically includes one connector link that includes one side bar  76 , 2 rivets that are semi-permanently connected to the side bar including cross holes for pass-through retainers or grooves for a snap ring or snap connector. This connector link is removable from the assembly and is used to form a continuous chain assembly that is wrapped around the desired sprockets. It is installed into the holes through the sidebars, and through the rollers on each end of the chain, and then a side mounting plate  76  is installed on the rivets and pass through retainers or a snap connector installed onto the rivets, after the chain sub assembly is properly installed onto the sprockets.  
         [0032]    This base chain sub assembly is repairable, but is not typically to be repaired in the field. Due to the mounting arrangement of the rivets  78  they do not substantially extend beyond the plane of the outside surface of the side mounting plates  76  and are typically not subjected to wear as the other components, as will now be explained. For the purpose of this invention this sub assembly, with the exception of the connector link, is considered to be permanently assembled.  
         [0033]    The chain assembly as seen in FIG. 3 also includes tube spacers  82 , mounting bolts  80 , nuts  96 , washers  94  and cutting teeth  84 ,  86 ,  88 ,  90 , and  92 . FIG. 3 shows a section of the chain assembly  70  with the components assembled and the teeth arranged in one of many possible patterns. The pattern includes both externally mounted cutting teeth  88  and  90  as shown in FIGS. 5 and 6 and internally mounted cutting teeth  86  as seen in FIG. 4. Long tube spacers  82 L are used for the externally mounted cutting teeth and short spacer tubes  82 S are used with internally mounted cutting teeth. The teeth, which can be designed with many different shapes and characteristics, can be arranged in a wide variety of patterns to provide unique cutting characteristics as required by the type of soil being trenched, or the width of the desired trench. The cutting teeth include a base portion with a first flat mounting surface  98  and a second flat mounting surface  100  opposite the first, and a hole through which the mounting bolts  80  can pass. The head of the mounting bolt  80  cooperates with the second mounting surface  100  of the cutting tooth. In these figures there is shown an optional washer  94  mounted between the head of the mounting bolt  80  and the second mounting surface  100  of the base portion of the cutting tooth. As shown in FIG. 4 the shape of the cutting tooth is typically curved away from the first mounting surface  98 . The type of cutting tooth or pattern in which they are installed on the base chain assembly, is not a part of this invention, the invention being applicable in all the possible configurations as will be understood by one skilled in this technology.  
         [0034]    [0034]FIGS. 4, 5, and  6  illustrate the prior art assembly and the interaction of various cross-sections of the chain assembly. Plane  1 , on both the left and right sides is defined by the outer most surface of the side mounting plates  76 . Anything that is located between Planes  1 L and  1 R will be substantially protected from excessive wear by the side mounting plates  76 .  
         [0035]    Plane  2 , on both the left and right sides, is defined by the second mounting surface  100  of the base portion of the externally mounted cutting teeth  88 , or  90 . In this manner the second mounting surface  100  of the cutting teeth serves as a wear surface when the cutting teeth are externally mounted. It is found, in actual use, that anything that is located between Planes  2 L and  2 R will be substantially protected from excessive wear by these surfaces of the cutting teeth. For instance nut  96  in FIG. 5 or FIG. 6 will be substantially protected and they typically do not experience excessive wear.  
         [0036]    Plane  3 , on both the left and right sides, is defined by the plane passing through the outer-most surface of the head of bolt  80 . The head of bolt  80  is the only material in that plane. The result is that the head of bolt  80  in that position experiences excessive wear. When the bolt head wears significantly it becomes impossible to get a wrench to properly engage with the bolt head, and it becomes impossible to disassemble the chain assembly with standard, non-destructive tools.  
       Best Modes  
       [0037]    FIGS.  7 - 10  illustrate a digging chain assembly  70  constructed in accordance with the current invention. The chain assembly  70  includes a base chain sub assembly that is considered to be permanently assembled as described previously as related to the prior art shown in FIGS.  1 - 6 . The remaining components of the chain assembly are also similar to those described in the prior art FIGS.  1 - 6  with the following exceptions.  
         [0038]    The cutting teeth have been modified to include a void  102  that is formed by removal of a portion of the second mounting surface  100 . This void  102  is designed such that it is defined by a fastener engaging surface  104  of the base portion of the cutting tooth that is between the second mounting surface  100  and the first mounting surface  98 . It is also defined by a surface of variable shape, a side  106 , also part of the base portion of the cutting tooth. This shape is designed to minimize the amount of material removed from the base portion of the cutting tooth, and the resultant stress level seen in the tooth upon loading in actual use.  
         [0039]    As a result of the addition of this void  102 , the head of the mounting bolts  80  is substantially located between Plane  2 L and Plane  2 R, as described in relation to prior art FIGS.  4 - 6 . These results in the heads of bolts  80  being protected from excessive wear by the second mounting surface  100  of the base portion of the cutting teeth.  
         [0040]    [0040]FIG. 7 illustrates the complete assembly. Due to the loading conditions on the cutting teeth, the selection of fasteners as well as the shape of the void are important details. The FIG. 7 and FIG. 11 illustrate a preferred embodiment of the invention wherein the fastener is a standard hex-headed bolt  80  and hex nut  96 . The void  102  is a counterbore wherein the diameter of the counterbore is sufficient to allow a standard socket that fits on the head of the bolt  80  or the cooperating hex nut  96  to be inserted for full engagement.  
         [0041]    The choice of a standard hex-headed bolt  80  is made to assure availability of a wide selection of bolt lengths and materials. As can be seen by comparing FIG. 8 with FIG. 9 the bolt  80  needs to be of different lengths to accommodate externally mounted or internally mounted cutting teeth. In addition it is possible to mount a cutting tooth on both sides of the base chain. This is not illustrated, but it is clear that this arrangement would require a slightly longer bolt.  
         [0042]    The selection of the counterbore  102  of tooth  188  as illustrated in FIG. 11 is made to minimize manufacturing cost, to maximize strength, and maximize flexibility. This type of configuration, including a hole  101 and a counterbore or void  102 , can typically be manufactured in one process with a specialized drilling tool, minimizing cost. This design can also be used in either single internal or external mounts as illustrated in FIGS.  8 - 10 . It can also be used in a double external mount not illustrated, wherein the head of the bolt  80  will be within the void  102  on one side and the cooperating nut  96  will be within the void  102  on the opposite side.  
         [0043]    [0043]FIG. 12 illustrates an alternate embodiment of the assembly wherein the bolt  80  has been changed from a standard hex headed bolt to a countersunk head bolt  80  with the mating void  102  in the cutting tooth base being correspondingly changed to a countersink. This figure also illustrates dual mounts, an assembly designed with cutting teeth specifically designed as dual mount teeth with alternating counterbored voids for engagement with a nut  96  and countersunk voids  102  for engagement with the countersunk head of the bolt  80 . The cutting teeth used for single external mount applications will have exclusively countersunk voids  102  for engagement with the countersunk head of the bolt  80 .  
         [0044]    [0044]FIGS. 13 and 14 Illustrate alternate embodiments wherein the voids in teeth  288  and  388  are a closed slot  202  and an open slot  302 . The slot  202  surrounds hole  201 . Both of these embodiments can be designed such that the width of the slot  202 ,  302  is equal to the width across flats of the bolt head selected. This results in the slot  202 ,  302  acting to hold the bolt from rotating, and installation requires simple insertion of the bolt into the slot  202 ,  302  with subsequent tightening of the nut  96  against the side mounting plate on the opposite side. This type of configuration is typically more difficult and more costly to manufacture than the embodiment of FIGS.  7 - 11 .  
         [0045]    [0045]FIG. 15 illustrates a digging chain assembly  70  constructed in accordance with the present invention with cup cutters  170 . FIG. 16 Illustrates a cup cutter constructed in accordance with the present invention. FIG. 17 illustrates another type of cutter  180 , known as a rotary cutter, constructed in accordance with the present invention.  
         [0046]    The nut  96  and bolt  80  is the preferred type of fastener for the present invention but other fasteners may be substituted for these nut and bolt fasteners.  
         [0047]    With regard to the foregoing description, it is to be understood that changes may be made in detail, especially in matters of the construction materials employed and the size, shape and arrangement of the parts with departing from the scope of the present invention. It is intended that the specification and the depicted aspects be considered exemplary only, with a true scope and spirit of the invention being indicated by the broad meaning of the following claims.