Abstract:
A coupler for a horizontal directional drill for quickly and easily attaching and detaching a stakedown assembly from the drill. The coupler includes a first coupler member and a second coupler member with matching angular front and Fear ends so that the first member fits within the second member. A lever operated locking mechanism releasably locks the two coupler members together in attached relationship.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to horizontal directional drill machines. It relates particularly to a stakedown assembly for a horizontal directional drill machine. 
     BACKGROUND OF THE INVENTION 
     A horizontal directional drill machine is a common and well-known machine for installing pipes beneath the ground and generally parallel to the surface. These machines are used in many different applications and are available in a wide range of sizes. Typical applications where a horizontal directional drill machine might be used include the installation of fiber optic cables, electrical cables, gas lines, water systems, or sewer systems. Horizontal directional drill machines are commonly rated in terms of pull-back capacity. Some machines for smaller applications have as little as five thousand pounds of pull-back capacity. Other machines are available with a pull-back capacity of as much as one million pounds. 
     One alternative to a horizontal directional drill machine is the traditional trencher machine. A trencher machine simply digs a trench into the ground, and after (for example) pipe is laid down in the bottom of the trench, the trench is filled and the pipe is buried. The advantage of a horizontal directional drill machine over a trenching machine is that a pipe can be buried in the ground over long distances without digging a trench. Thus, a horizontal directional drill is particularly desirable when a trench would be difficult or too costly to dig. For example, a horizontal directional drill machine finds particularly advantageous application for installing pipes under roadways, where destruction of the road is expensive and inconvenient to travelers, or under a waterway like a river, where trenching would be impossible. 
     A unique aspect of a horizontal directional drill machine is the special drill head that is attached to the front end of a pipe to be laid. The drill head has an angled shape which allows the operator to change the direction of the pipe after it has entered the ground. Direction changes are achieved by stopping the pipe and drill head rotation and orienting the drill head at a desired angle. Then, by pushing on the drill pipe without rotating it, the drill head and attached pipe will veer in the desired direction. Thus, by affecting directional changes to pipe travel, a pipe might enter the ground at an angle, travel horizontally over a long distance, and exit the ground at another angle. This ability to change the direction of pipe travel also allows the operator to steer the pipe around underground obstacles like boulders. 
     In addition to pushing forces which must be applied to the pipe as it is inserted, it is often necessary to pull back on the pipe. This may be necessary when a direction change is not completely successful on the first attempt, or when an underground obstacle like a boulder is encountered. The machine then pulls the pipe and drill head back to permit a direction change. 
     The push and pull forces that a horizontal directional drill machine must apply to the drill pipe frequently exceed the weight of the machine itself. Therefore, a system is required to anchor the machine and resist these forces. The most common system for anchoring the drill machine comprises the use of stakes mounted on the machine body which are screwed into the ground. The stakes have flighting on their tips and are driven into the ground by applying simultaneous rotational and vertical driving forces to each stake. To drive and remove these stakes, a stakedown assembly is conventionally provided on the end of the drill machine where the drill head enters the ground. 
     Often it is necessary to move a horizontal directional drill before the entire pipe length has been drilled and the job completed, however. This can occur because another project becomes more urgent or when repairs to the machine are needed. Additionally, horizontal directional drill machines are expensive. Therefore, some operators find it necessary to remove the drill machine from the job site each night to protect their investment. However, in order to achieve optimal drilling results, it is desirable to avoid restaking operations. Among other deleterious effects, the removal and later reinstallation of the stakes can weaken the underlying soil, and thus reduce the push-pull forces that can be resisted. 
     It is therefore desirable to facilitate quick and easy coupling between the horizontal directional drill and the stakedown assembly. Such coupling would allow the operator to easily disconnect the drill from the stakedown assembly. The stakes could then be left installed in the ground while the drill was transported elsewhere. When the drilling operation is later continued, the drill can be reconnected to the stakedown assembly without the need for a restaking operation. 
     BRIEF SUMMARY OF THE INVENTION 
     It is an object of the invention to provide a new and improved coupling for quickly and easily connecting and disconnecting a stakedown assembly and a horizontal drill machine. 
     According to the invention, the coupling includes a first coupling member that is pivotally attached to the drill and a second coupling member that is integrated with the stakedown assembly. The first coupling member is acutely angled on its front end and obtusely angled on its rear end. The second coupling member has substantially matching angles so that the first member fits within the second member in the attached position. 
     A locking mechanism is provided for binding the two members together in the attached position. This locking mechanism is installed within the first member. In the preferred embodiment, the locking mechanism includes a tapered pin that wedges into matching holes in the first and second members. A cam is used to engage the pin, while a return spring disengages the pin. 
    
    
     BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS 
     The invention, including its construction and method of operation, is illustrated more or less diagrammatically in the drawings, in which: 
     FIG. 1 is a side elevational view of a horizontal directional drill, showing the drill in its operating mode; 
     FIG. 2 is a side elevational view of a horizontal directional drill, showing the drill disconnected from the stakedown assembly, where the drill is in its transporting mode and the stakedown assembly is staked to the ground; 
     FIG. 3 is an enlarged longitudinal sectional view of the coupling, in a connected position; 
     FIG. 4 is a similar view of the coupling, in the disconnected position; and 
     FIG. 5 is a top plan view of a component of the coupling in its locked state; and 
     FIG. 6 is a view similar to FIG. 5 showing the coupling component in its unlocked state. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings, and particularly to FIG. 1, a horizontal directional drill machine is shown generally at  10 . The drill machine  10  includes a frame  12  supported by driven tracks  14  for moving the drill machine  10  from place to place. 
     The drill machine  10  includes a longitudinally elongated boom  16  pivotally mounted on the front end of the frame  12 , as at  17 . A conventional pipe drill assembly  18  is mounted on the boom  16 , extending coextensively therewith. The drill assembly  18  is designed to drill a series of pipe sections P 1 , P 2 , P 3 , et seq., into the ground, in sequence. 
     In the operating mode of the drill machine  10 , the boom  16  is pivoted upward away from the frame  12  so that pipe section P 1  extends from the drill assembly  18  and intersects the ground at an angle. A special drill head (not shown) is attached to the front end of the first drill pipe section P 1 . In order to drill the pipe section P 1  into the ground and make any desired directional changes in its path, a variety of push, pull, and rotational forces are applied to the pipe section P 1  by the drill assembly  18 . The manner in which the drill assembly  18  applies these forces to the drill pipe section P 1  are not described, but are well known to those skilled in the art. 
     As the first pipe section P 1  is drilled into the ground, new pipe sections P 2 , P 3 , et seq., are successively attached to the rear end of the preceding pipe sections. A cartridge  22  of pipe sections P 2 ,. P 3 , et seq. is provided on the boom  16  for storing these additional pipe sections, and a semi-automatic or fully automatic loader (not shown) may be provided for attaching them to the preceding pipe sections. 
     A stakedown assembly  24  is connected to the front end of the drill machine  10 . The stakedown assembly  24  is attached to forward end of the boom  16  at a pivot connection  26 , which allows the stakedown assembly  24  to be oriented level with the ground surface when the boom is tilted. A coupling  40  embodying features of the present invention is provided to quickly and easily connect the stakedown assembly to the drill machine  10 , or disconnect it. 
     Turning now to FIG. 2, the horizontal directional drill machine  10  is shown disconnected from the stakedown assembly  24 . The stakes S remain installed in the ground in their original positions. The boom  16  is pivoted back to a horizontal position so that the boom  16  is resting on the frame  12 . The drill  10  can then be moved to another place in a conventional manner. 
     Now referring to FIGS. 3 through 4, where FIG. 3 shows the machine and stakedown assembly  24  connected and FIG. 4 shows them disconnected, the coupling  40  includes a first coupling member  50  and a second coupling member  60 . The first coupling member  50  is attached to the drill machine  10  at a pivot connection  26 , as previously described. The second coupling member  60  is incorporated as a integral part of the stakedown assembly base plate  32 . 
     Referring additionally to FIGS. 5 and 6, the first coupling member  50  includes a horizontal base plate  52 , a face plate  53 , a tail plate  54  and side plates  55 . The plates  53  and  54  are each inclined rearwardly at an angle to 30° to the vertical. The side plates  55  connect them. 
     Mounted on the base plate  52  is a locking mechanism  70 . The locking mechanism includes a locking pin  72  slidable longitudinally of the base plate  52  in a sleeve  73 . At its rear end  74 , the pin  72  has a beveled locking tip  75  which is arranged so that it will pass longitudinally into and through an opening  76  in the tail plate  54  when it slides rearwardly in its sleeve  73 . As will later be explained, it is this locking tip  75  which engages and locks the coupling member  50  into the coupling member  60  when the former is properly seated. 
     The front end  81  of the locking pin  72  has an actuator rod  82  pivotally connected to it, as at  83 . The rod  82  extends forwardly of the pin  72  through a connector block  85  pivotally mounted on the toe  86  of an actuator lever  80 . The lever  80  is, in turn, mounted on a pivot pin  91  for pivoting movement about the pin  91 . 
     The rod  82  is slidable in the connector block  85 . The block  85  is freely rotatable in the toe  86 . A nut  91  is threaded onto the end of the rod  82 . A coil spring  92  encircles the rod  92  between two washers  93 ,  94 . It will thus be seen that rotating the lever  80  about its pivot pin  91  in a clockwise direction will resiliently push the locking pin  72  into the position shown in FIG. 5, while rotating it in a counter-clockwise direction will subsequently pull the pin forwardly into the position shown in FIG.  6 . 
     The toe  86  of the actuator lever  80  is located at the end of a foot  96  of the lever, as will be seen. The foot  96  extends generally perpendicular to the leg  88  are formed so that a cam  97  is created at their juncture. When the lever  80  is rotated from the position seen in FIG. 6 to that seen in FIG. 5, this foot  96  and cam  97  pass through axial alignment with the pin  72 , over dead center relative to a straight line between the pin  91  and pivot connection  83  and the pin  72  is resiliently held in its locking position. 
     To disengage the pin  72 , the lever  80  is turned in the reverse direction, thus, removing the applied force. The return spring  92  is provided to apply a rearward force to the locking pin  72  to return it to the disengaged position. 
     The second coupling member  60  has a well  101  formed between a rearwardly inclined front wall  102  and a rearwardly inclined rear wall  103 . The rear wall  103  has a locking aperture  105  formed longitudinally through it. The well  101  is configured to slidably receive the coupling member  50  into it in the manner shown in FIG.  3 . The locking pin  72  can then be moved rearwardly so that its tip  75  extends into the locking aperture  105  and the coupling member  50  is locked in the coupling member  60 . 
     While a preferred embodiment of the invention has been described, it should be understood that the invention is not so limited, and modifications may be made without departing from the invention. The scope of the invention is defined by the appended claims, and all devices that come within the meaning of the claims, either literally or by equivalence, are intended to be embraced therein.