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RELATED APPLICATIONS/PRIORITY BENEFIT CLAIM 
       [0001]    The present application claims priority to Bolivian patent application SP 0127-08 filed Apr. 18, 2008 in the Bolivian Patent Office (SENAPI—Servicio Nacional De Propriedad Intelectual—Bolivia), by the same inventors (Delius and Aeschbacher), the entirety of which Bolivian patent application is incorporated herein by reference. 
       FIELD OF THE INVENTION 
       [0002]    The invention is in the field of accessories for providing an excavator with a dual function in earth-moving tasks: digging and refilling trenches, and as a crane (hoisting capability), to be used with advantage in the construction of pipelines. 
       BACKGROUND OF THE INVENTION AND DESCRIPTION OF RELATED ART 
       [0003]    In a construction work with mechanical facilities, such as pipe laying, particularly in the petroleum and gas industry, pipes are required for transporting fluids (hydrocarbons and water). 
         [0004]    In the construction of pipelines, two types of machines are required: excavators and pipe layers. 
         [0005]    Excavators are required for earth-moving tasks: 
         [0006]    1. Clearing and preparation of the right of way 
         [0007]    2. Digging trenches 
         [0008]    3. Refilling the trenches once the pipes have been laid in the bottom of the trench. 
         [0009]    Pipe-layers are required for various operations, such as:
       1. Unloading and placing the pipes alongside the trench   2. Assisting in cold bending of pipes   3. Assisting in welding of individual pieces of pipes forming a pipeline   4. Lowering the pipeline into the trench   5. Special work such as, joining of lines during the building of special sections and other hoisting work.       
 
         [0015]    In conventional operations, two types of expensive machines are required. The excavator is limited to earth moving tasks and the pipe layer is specialized in hoisting and pipe laying operations. 
         [0016]    Excavating machines typically consist of a lower body made up of tracks that facilitate the movement, an upper body joined to the lower one by a bearing which allows rotation (vertical rotation axis) of the upper body in relation to the lower body. In the upper body, an engine, a counterweight, the operator&#39;s cabin, and a boom moveable on a horizontal pin whose movement is achieved by means of hydraulic cylinders are installed. At the top of this boom a jib is installed, articulated to the boom by a pin parallel to the previous one. The movement of the jib is achieved by a hydraulic cylinder. Likewise, at the top of this jib, an excavating bucket is installed by means of a pin parallel to the previous ones, and its movement is achieved by a hydraulic cylinder. 
         [0017]    A variation on the standard excavator is the mine dragline: an excavator as described above equipped with a special boom and winch designed to drag a bucket in mining operations. They are also used as cranes. 
         [0018]    Some excavating machines have dual function, for example an excavator as described above, in which the boom, the jib and the bucket have been removed and replaced by a special boom and a winch installed by means of a special adaptor. These machines are used as pipe layers and excavators (Patent request pending USA WO 2006/121441 A2; Davis Pipe-layer Inc.). 
         [0019]    Track mounted pipelayers are special machines designed for pipeline construction. They are based on tractors with special caterpillar tracks and have a swinging boom installed around an axis parallel to the longitudinal axis of the tractor and is fixed to the supporting frame of the tracks. The inclination of the boom is controlled by means of hydraulic systems or by a combination of winch and cable. Another winch operates the lifting cable. On the opposite side of the boom a fixed or moveable counterweight is installed. 
       BRIEF SUMMARY OF THE INVENTION 
       [0020]    According to the invention, with the use of this accessory, one machine, a hydraulic excavator, whose standard function is earth movement tasks, is converted into a machine which can also be used for lifting heavy loads as required during pipeline construction. The objective of the invention is to provide a multi-purpose machine capable of fulfilling the roles of lifting cargo, suspending loads in the air, the unloading of pipes and placing them in the required position, lifting other cargo in mechanical assembly operations, movement of cargo and, furthermore, carrying out earth moving tasks. 
         [0021]    This is achieved by an accessory consisting of a frame, a winch with a hydraulic motor and a sheave installed at the top of the boom of a common excavator without having to modify the original machine. 
         [0022]    The accessory comprises a frame, sheaves and a winch with hydraulic action, installable on top of the boom of a hydraulic excavator without involving modifications to the original machine, thereby providing the excavator with hoisting capability. 
         [0023]    The advantage of this invention in relation to the present state of the technology used in pipe laying (track mounted) is that, since the excavator has a body with a boom capable of rotating around the lower body by means of a vertical shaft, it greatly facilitates all loading and unloading operations given that they can be carried out irrespective of the location of the machine (it can rotate 360 degrees). This feature is what makes this machine stand out from the pipe layers based on tractors with caterpillar tracks which, in order to change the position of the boom, have to turn the entire machine. This movement is achieved by moving the caterpillar tracks. 
         [0024]    With regard to the state of technology presented by Davis, the proposed invention differs in that it is significantly more economical from the investment point of view. Furthermore, it requires considerably less time and effort; fewer resources are needed to change from one operating mode to another (for example, another crane to assist in the positioning of the supporting structure of the winch and the boom). Last, but not least, it requires less space which reduces the cost of transporting the unit to the building site. 
         [0025]    These and other features and advantages of the invention will become apparent from the detailed description below, in light of the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]      FIG. 1  is a perspective view showing (in dotted lines) an excavator equipped with the proposed accessory ready to operate in the pipe-laying mode. 
           [0027]      FIG. 2  shows in greater detail (in dotted lines) the top of the excavator boom in pipe-laying or crane mode, the jib hydraulic cylinder and the hydraulic fluid supply and return lines of the bucket operating cylinder. 
           [0028]      FIG. 3  shows the accessory in greater detail, particularly the configuration of the supporting plates. 
           [0029]      FIG. 4  is similar to  FIG. 3 , but shows the accessory in greater detail as seen from the other side. 
           [0030]      FIG. 5  shows an excavator equipped for the pipe-laying or crane mode with the boom in the highest position and, in dotted lines, in the lowest position, and also shows the inventive accessory. 
           [0031]      FIG. 6  is a side elevation view of the accessory on the ground. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0032]      FIG. 1  shows (in dotted lines) an excavator equipped with the proposed accessory ready to operate in the pipe-laying mode. The jib, the bucket or work tool and the system for activating the bucket movement have all been removed. The upper body ( 2 ) is turned at an angle of 90 degrees to the lower body ( 1 ). Likewise, the counterweight ( 4 ), the operator&#39;s cabin ( 5 ), the excavating arm cylinder ( 11 ), the boom ( 6 ), the pin ( 15 ) that connects both the jib and the accessory ( 3 ) used in the pipe-laying mode to the top of the boom ( 6 ) are all visible. 
         [0033]    The accessory (continuous lines) consists of a frame, a winch ( 30 ), the sheave ( 18 ) and a sheave with a lifting hook ( 38 ). 
         [0034]      FIG. 2  shows in greater detail (in dotted lines) the top of the excavator boom ( 6 ) in pipe-laying or crane mode, the jib hydraulic cylinder ( 11 ) and the hydraulic fluid supply and return lines ( 32 ) of the bucket operating cylinder. Likewise, the rapid couplings ( 33 ) for connecting the hydraulic fluid flexible hoses are visible. 
         [0035]    The accessory of this invention (in continuous lines) consists of a frame plate ( 16 ) to which the supports ( 17 ) have been welded. The layout of the frame plate ( 16 ) and the support plate ( 17 ) allows the accessory ( 3 ) to be fixed to the top of the boom ( 6 ) by a pin ( 15 ). This pin ( 15 ) is the same one that holds the jib in place. 
         [0036]    Furthermore, the pin ( 10 ) that holds the eye ( 23 ) of the cylinder rod ( 11 ) is seen, so that the cylinder ( 11 ) does not move out of place when the machine is in the pipe-laying or crane mode; The winch ( 30 ) with hydraulic brake and motor ( 27 ) is held to the frame plate ( 16 ) by bolts ( 31 ). The sheave ( 18 ) is supported by a pin that allows it to align itself in function of the direction of the lifting cables ( 26 ). Connections of the flexible hoses ( 34 ) that connect the hydraulic motor ( 37 ) to the fluid supply and return lines ( 32 ) by means of rapid couplings ( 33 ) are also seen. It is by means of this connection that the winch ( 30 ) is controlled by the hydraulic circuit that operates the movement of the bucket or tool. 
         [0037]    Between the fluid supply connection ( 26 ) for the extention of the cylinder ( 11 ) and the fluid connection for the retraction ( 27 ) of the cylinder ( 11 ) a by-pass valve ( 25 ) has been installed for the purpose of preventing the accidental operation of this cylinder when the accessory is installed. This valve is open in pipe-laying and crane mode and closed in excavation mode. 
         [0038]    In  FIG. 3  the accessory ( 3 ) is seen in greater detail, particularly the configuration of the supporting plates ( 17 ). These plates are welded to the frame ( 16 ) and are separated from each other so that they will fit in the interior of the fork ( 14 ) of the boom ( 6 ). 
         [0039]    The accessory is fixed to the boom by the pin ( 15 ) that passes through the holes ( 8 ) in the boom and the holes ( 9 ) in the supports ( 17 ). A cut out ( 12 ) adapted to the profile ( 13 ) of the fork holds it in place firmly not allowing any displacement or rotation. 
         [0040]    Through the holes ( 19 ) of the supports ( 17 ), a pin ( 10 ) is placed to support the eye of the jib cylinder( 11 ). 
         [0041]    A sheave ( 18 ) to increase the pulling force of the lifting hook is held in place by a pin ( 21 ) and a couple of supports ( 22 ) welded to the frame, ( 16 ) allowing the alignment of the sheave in function of the direction of the lifting pull. 
         [0042]      FIG. 4  shows the accessory ( 3 ) in greater detail as seen from the other side. The frame plate ( 16 ), the winch ( 30 ) with hydraulic motor ( 37 ), the accessory support plates ( 17 ) with the holes ( 19 ) for the connecting pin ( 15 ) and the profile ( 12 ) shaped like the boom fork are all seen. Likewise, the sheave supports ( 22 ), the sheave ( 18 ) and the connecting pin between the supports ( 22 ) and the sheave ( 18 ). Finally, the supports holding the end of the lifting cable ( 26 ) can be seen welded to the frameplate ( 16 ). 
         [0043]      FIG. 5  shows an excavator equipped for the pipe-laying or crane mode with the boom ( 6 ) in the highest position and, in dotted lines, in the lowest position is shown.  FIG. 5  also shows the accessory ( 3 ) with the winch ( 30 ) and sheave ( 18 ) and, likewise, a sheave with a lifting hook ( 38 ). The jib cylinder ( 11 ) which is fixed to the accessory by a pin ( 10 ). The accessory ( 3 ) is fixed to the top of the boom by a pin ( 15 ). 
         [0044]    It will be understood that while the disclosed embodiments illustrate the presently preferred forms of the invention, they are intended to be explanatory rather than limiting with respect to the invention. Reasonable variations and modifications of the invention as disclosed in the foregoing description and drawings are possible without departing from the scope of the invention. The scope of the invention is defined by the following claims.

Summary:
Accessory for providing an excavator with a dual function in earth-moving tasks: digging and refilling trenches, and as a crane (hoisting capability), to be used with advantage in the construction of pipelines. The accessory includes a frame, sheaves and a winch with hydraulic action, installable on top of the boom of a hydraulic excavator without involving modifications to the original machine, thereby providing the excavator with hoisting capability.