Abstract:
An undercarriage having tracks or the like is attached thereto is provided for moving the undercarriage along the ground. A turret is attached to the undercarriage along a first substantially vertical axis so that the turret can rotate. A backhoe is pivotally attached to the turret along a second substantially vertical axis. A trencher is operatively attached to the turret and occupies an area adjacent the undercarriage. Structure is provided for preventing the backhoe from moving into an area occupied by the trencher.

Description:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable 
     BACKGROUND OF THE INVENTION 
     The present invention relates to machines for excavating soils as necessary in construction projects. More specifically it relates to a machine that is adapted specifically for long narrow trenches and at the same time for more general excavations. 
     Long narrow trenches are required for installation of many utilities including water and sewer, gas, electrical power, and cable for communications. These utilities are often installed using machines known as trenchers, one example is illustrated in FIG. 1. A trencher  10  includes a trenching boom  40 , with a boom frame  42  that supports an excavation chain  44  routed around and supported by end idler  46 . The trenching boom  10  is mounted to a mobile chassis  12  capable of propelling the boom through the ground while the boom is lowered into the ground such that the end idler  46  is in a position to excavate to the desired depth. There are two basic types of chassis, a track chassis and a rubber tire chassis. FIG. 1 illustrates a rubber tire chassis, and that type of trencher is thus known as a rubber tire trencher. 
     Rubber tire trenchers have an advantage over track trenchers in that they are less disruptive to the ground. Thus, they are utilized in applications where maintaining the ground is important, such as when trenching through established yards. In this application the needed excavation varies widely. Thus, rubber tire trenchers typically include a variety of excavating attachments and can include a vibrating gearbox and mount for a plow on the rear of the machine beside the trenching boom, not shown, while including a backhoe  20  and blade  30  attached to the front of the rubber tire trencher  10 . 
     While the rubber tire trencher offers great flexibility, its capability for general excavation with the backhoe  20  is somewhat limited by the chassis. The backhoe can be positioned around its pivot axis  22  while being controlled by an operator positioned in operator station  14 . Any additional movement of the backhoe requires movement of the entire chassis. 
     Different machines have been developed for general excavation, and are generally known as Excavators, an example being a compact excavator  110  as illustrated in FIG.  2 . The compact excavator  110  has evolved to include two basic parts, an undercarriage or chassis  112  and turret/turntable  116 . The undercarriage  112  includes the chassis and typically tracks. It supports the turret/turntable  116  and typically also supports a backfill blade  130 , which is positioned with cylinder  132 . 
     The upper structure, turret or turntable  116  includes the power unit, typically a diesel engine and hydraulic system, the operator&#39;s station  114 , and a backhoe  120  mounted on a pivot  122 . There is no limitation of the rotation of the turntable, it is able to rotate fully, mounted to the undercarriage  112  at the swivel joint, supported by a slew bearing. The swivel joint supports the turret  116  and further provides a valve to provide a flow path for oil to be transferred from the pump, a component of the power unit, to the track drive motors and cylinder that positions the backfill blade  130 . This valve is constructed to allow the turret to rotate freely. 
     The operator&#39;s station  114  is mounted on the turret  116 , and the pivot for the backhoe  122  is positioned directly in front of the operator&#39;s station. This arrangement provides good visibility of the backhoe  120 , and provides for flexibility in applications. Examples of this flexibility are illustrated in FIG. 3 where the excavator  110  is shown digging near to an existing wall  2 . In these illustrations it can be seen how the chassis  112  can be positioned near the wall  2 , the turret  116  rotated such that the backhoe pivot  122  is adjacent the wall, and the backhoe  120  positioned parallel to the wall. As positioned, the bucket can scoop in a direction parallel to the wall to form trench  4 . Once the bucket is full it can be lifted, and the backhoe  120  rotated in order to position the backhoe and bucket to a second position  120   a , away from the wall, to drop the excavated material in a pile or into a truck. 
     Excavators have become a preferred arrangement for general excavation. However, when a job involves specifically forming a trench of a specific depth and width, this arrangement is not as productive as the trenching boom described earlier as a part of the rubber tire trencher, particularly when the trench is narrow. 
     FIG. 4 illustrates the use of a compact excavator  110 , positioned in four different locations  110   a ,  110   d ,  110   c , and  110   d , as would be necessary to dig a trench. The compact excavator is operated in the first position  110   a , while the backhoe  120  is utilized to dig a first section of the trench. After completion, the chassis is moved to a second position  110   b , and the trench extended. This process is repeated  110   c , and  110   d  until the trench is the desired length. This process requires a substantial amount of operator involvement. 
     By contrast, the rubber tire trencher is illustrated in FIG. 1 will require less operator involvement. This involvement includes first controlling the trenching boom  40  during a plunge-cut, as the boom is rotated clockwise to move the end idler  46  from a position above the ground, to a position where a trench of the desired depth is being formed. Subsequent operator control then involves adjusting the ground speed of the rubber tire trencher  10  to match the excavation capacity of the trenching boom  40 . 
     Trenchers have not previously been installed onto compact excavators. 
     BRIEF SUMMARY OF THE INVENTION 
     According to the present invention there is provided a modification to a compact excavator by adding an optional component, a chain trencher. 
     A broad object of the present invention is to provide an excavator with a trencher. 
     Another object of the present invention is to provide an excavator with a trencher in a way that will automatically prevent a backhoe portion of the excavator from coming in contact with the trencher. 
     Still another object of the invention is to employ such an excavator with a trencher in a way that will automatically prevent a backhoe portion of the excavator from coming in contact with the trencher, but also use a mounting structure for the backhoe which allows the backhoe to move around 360 degrees once the mounting structure and trencher is removed. 
     Other objects, advantages, and novel features of the present invention will become apparent from the following detailed description of the invention in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side view of prior art machine adapted for digging a trench known as a rubber tire trencher; 
     FIG. 2 is an isometric view of prior art machine adapted for general excavation known as a compact excavator; 
     FIG. 3 is a top view of a prior art compact excavator illustrating the digging boom in various positions; 
     FIG. 4 is a side view of a prior art compact excavator illustrating the process of digging a trench; 
     FIG. 5 is an isometric view of the compact excavator of the present invention including a trenching boom, 
     FIG. 6 is a top view of a compact excavator of the present invention including a trenching boom with portions cutaway to show some of the components of the alternate embodiment shown schematically in FIG. 12; 
     FIG. 7 is an isometric view from a low position and with one of the tracks removed and the trencher removed to expose the mounting structure for the trenching boom; 
     FIG. 8 is a top view with the trencher in the same position as illustrated in FIG. 6, with a portion of the turret cut-away to show a stop structure; 
     FIG. 9 is a view similar to FIG. 8 with the turntable rotated to the position where it is stopped against the second stop, with a portion of the turret cut-away to show a portion of a stop structure; 
     FIG. 10 is an exploded isometric view showing the compact excavator, the trencher boom mount and the trenching boom; 
     FIG. 11 is an isometric view showing the compact excavator, with the trenching boom raised into a transport position; and 
     FIG. 12 is a schematic view of an alternate embodiment. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings, like reference numerals designate identical or corresponding parts throughout the several views. The included drawings reflect the current preferred and alternate embodiments. There are many additional embodiments that may utilize the present invention. The drawings are not meant to include all such possible embodiments. 
     FIG. 5 illustrates a preferred embodiment of the present invention, a compact excavator  110  with a trenching boom  140  attached to the undercarriage  112 , supported on tracks  113 . The trenching boom  140  includes boom frame  142 , excavating chain  144 , and end idler  146 . The trenching boom  140  will function in a manner identical to that described for the rubber tire trencher of FIG. 1, including the ability to pivot about axis  148  between a lowered position, as illustrated, and a raised position. In the lowered position, the end idler  146  has been lowered to position the excavating chain  144  to form a trench of the desired depth. During the excavation process, the excavating chain  144  engages the ground while the boom frame  142  forces it into this engagement with a down-force sufficient to make the excavation efficient. The boom frame  142  is positioned by cylinder  150  which transfers a portion of the overall weight of the compact excavator  110  from the tracks  113  to the boom frame  142 . This weight transfer is optimized by keeping the pivot  148  of boom frame  142  near to the center of gravity of the compact excavator  110 . 
     FIG. 6 illustrates the mounting of the trenching boom  140  to the compact excavator  110 . The mounting is accomplished with two main components including a trencher attachment frame  160  and trencher mount frame  152 . The attachment frame or sub-frame  160  includes a trencher mounting pad  162  that is positioned in close proximity to the tracks  113 , leaving clearance required for proper function of the tracks. The attachment frame or sub-frame  160  could have attachments other than the illustrated chain trencher, such as rock wheel trenchers, plows for installing utility lines, etc. 
     The trencher mounting pad  162  is configured to include a series of mounting holes  163 , shown in FIG. 5, that allow the trencher mount frame  152  to attach in a number of different locations, in order to change the location of the trenching boom  140  relative to the tracks. The trencher-mount frame  152  further provides support for cylinder  150 , for the rotational connection that defines pivot axis  148  and for the trencher motor  154 . In this manner the trenching boom  140  is positioned such that a sufficient down-force can be generated to provide for efficient excavation. 
     In this FIG. 5 position, without the stop structure  118  and stop pads  168  described below, the backhoe  120  could contact the trenching boom  140 , or its mounting components. Thus when the trenching boom  140  is mounted to the compact excavator the ability to freely rotate the turntable  116  will be restricted, as the backhoe  120 , depending on where it is positioned relative to the turntable  116 , may interfere with the trenching boom  140  or its mounting components. 
     The present invention places an attachment, a trenching boom  140 , onto a compact excavator in a position where it limits the rotational travel of the turntable. The operator will be required to be aware of the position of the backhoe  120  whenever the turntable is rotated to avoid interference of the components. 
     A further aspect of the present invention is to provide limits that will reduce the burden on the operator, by introducing an automatic limitation to reduce the probability of damage. A preferred embodiment is illustrated in FIGS. 7 and 10. The trencher attachment frame or sub frame  160  includes the trencher mounting pad  162  on a first end, and is adapted to attach to the undercarriage  112  on the opposite end with an adapter pad  164 . It further includes stop arms  166  supporting stop pads  168  as shown in FIGS. 8-10. The trencher attachment frame or sub frame  160  is configured to be easily attached to the undercarriage  112  and can easily be removed when the trencher boom  140  will not be used. In this manner, when the trencher attachment frame or sub frame  160  is removed from the compact excavator  10 , the stop pads  168  are also removed. 
     FIGS. 8 and 9 illustrate the function of the stop pads  168 . In FIG. 8 the turntable  116  has been rotated clockwise to a position where a turntable stop bracket  118  has contacted the first stop pad  168 . The turntable stop bracket  118  attaches to the turntable, extending from the bottom surface as shown in FIG.  7 . Stop bracket  118  is a V-shaped bracket with a first surface  118   a  and a second surface  118   b . In FIG. 8 surface  118   a  is illustrated in the cut-away section of the turntable  116  in contact with the first stop pad  168 . 
     In FIG. 9, the turntable has been rotated counter-clockwise until the second surface  118   b  of turntable stop bracket  118  has contacted the second stop pad  168 . In this manner, whenever the trencher attachment frame  160 , including the stop pads  168 , is mounted to the compact excavator  110 , the rotation of the turntable  116  will be limited. 
     With this limitation, the backhoe  120  can still be positioned to interfere with the trenching boom  40 , for instance if the boom were pivoted counterclockwise around its pivot  122  from the illustrated position in FIG.  6 . However, when the backhoe  120  is centered, as illustrated in FIG. 6, the backhoe will not interfere. The potential for interference is higher when the trenching boom  140  is in a raised, transport position as illustrated in FIG.  11 . However, with the compact excavator of the present invention, the operator has simply to position the backhoe in the center position, and then can be confident that there will not be any interference when rotating the turntable in order to operate the trenching boom. 
     FIG. 6 illustrates the mechanical elements that control the position of the backhoe, and of the turntable. The backhoe is positioned by a hydraulic cylinder  208 , which is typically directly controlled by a joystick, actuated by the operator. The position the backhoe could be determined with a device  202  capable of measuring the linear travel of cylinder  208 . 
     A rotary actuator, such as a hydraulic motor, positions the turntable which powers a gear  206  mounted onto the turntable that engages a gear  207  mounted onto the chassis. The position of the turntable can be determined, in a variety of methods, for example with a transducer  204  mounted by and actuated from the gears. In this example transducer  204  is mounted on the turntable such that it detects whenever it travels past a tooth of gear  207 . By constantly monitoring this transducer, the position of the turntable can be continuously monitored. Another example would be to place transducer  204  on the turntable such that it detects certain targets mounted onto the chassis, such that it is possible to detect certain positions of the turntable. 
     An alternative embodiment that would further reduce the burden on the operator is illustrated schematically in FIG. 12, and would incorporate an electronic controller  200  to control the stopped positions as a function of the position of the backhoe  120 . The electronic controller  200  would be capable receiving inputs from transducers  202  and  204 , described previously as detecting the position of the backhoe and the position of the turntable. It will further be capable of receiving inputs  220  from the operator. In response it will control valve  210 , that controls hydraulic power to the cylinder  208  that positions the backhoe, and the hydraulic motor that rotates gear  206  to control the rotational position of the turntable. Controller  200  will include memory and computational capacity such that the turntable would be stopped at various positions, depending on where the operator had left the backhoe, as necessary to prevent interference between the backhoe and the trencher. 
     Controller  200  includes computational capacity such that the position of the backhoe will be controlled based on the position of the turntable. Thus, when the turntable is rotated such that the operator is in the vicinity of the trencher boom, the backhoe is prevented from being rotated around its axis into a position where it could interfere with the trencher boom. 
     Obviously many modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.