BACKGROUND OF THE INVENTION
- SUMMARY OF THE INVENTION
Various pieces of equipment have been developed for digging vertical holes in the earth for construction purposes, such as postholes and holes for receiving foundation pilings and anchoring structures. Although specialized pieces of equipment have been developed for digging vertical holes in the earth, there has been a need for hole digging equipment or devices which may be adapted for attachment to the boom of hydraulic excavating equipment, such as a so-called backhoe apparatus. The provision of such a device as a removable attachment increases the versatility and usefulness of expensive construction equipment, such as hydraulic excavators or so-called backhoes. The provision of a removable hole digging device also eliminates the need for a specialized piece of hole digging equipment which would otherwise be idle when not needed. It is to these ends that the present invention has been developed.
The present invention provides a hole digging device, particularly adapted for removable attachment to and use in combination with an excavator apparatus, including, in particular, a hydraulic excavator or backhoe.
In accordance with one aspect of the present invention, a hole digging device is provided which includes opposed digging blades pivotably connected to each other and forming a substantially cylindrical digging device or shovel, not unlike a manual posthole digger, but wherein the digging device is particularly adapted for attachment to the distal end of a movable boom of a hydraulic excavator or the like. The hole digging device includes opposed arms which are fixed to one of the digging blades and are adapted for connection to spaced apart support pin members on the boom of the excavator apparatus. The other digging blade of the device includes a connector for connecting the other blade to an extensible hydraulic cylinder and piston actuator mounted on the boom and otherwise used for manipulating an excavator bucket.
Accordingly, the present invention provides a device which is easily substituted for the hydraulic actuated excavating bucket or backhoe bucket normally connected to the distal end of a movable boom of an excavator apparatus. In this way a hole digging device is provided which does not require separate hole digging equipment, such as the more common motorized auger type hole digger, an expensive piece of equipment which would otherwise sit idle when not needed for digging post, piling or anchor holes, for example.
BRIEF DESCRIPTION OF THE DRAWINGS
Still further, instead of requiring two expensive pieces of equipment, one of which might sit idle while the other is in use, the hole digging device of the present invention increases the versatility of an excavator, backhoe or similar apparatus while permitting substitution of the hole digging device for an excavator bucket or other boom mounted attachment. Those skilled in the art will further appreciate the abovementioned advantages and superior features of the invention together with other important aspects thereof upon reading the detailed description which follows in conjunction with the drawings.
FIG. 1 is a side elevation of a unit of construction equipment comprising a hydraulic excavator, to which is connected the hole digging device of the present invention;
FIG. 2 is a detail view of the hole digging device on a larger scale;
FIG. 3 is a detail section view taken along line 3-3 of FIG. 2; and
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
FIG. 4 is an exploded perspective view of the hole digging device of the present invention.
In the description which follows like parts are marked throughout the specification and drawing with the same reference numerals, respectively. The drawing figures are not necessarily to scale and certain features may be shown exaggerated in scale or in somewhat schematic form in the interest of clarity and conciseness.
Referring to FIG. 1, there is illustrated a unit of construction equipment comprising a hydraulic excavator 10. The excavator 10 includes a track mounted swiveling platform 11 on which is mounted a power unit 11 a, typically comprising a diesel engine driving a hydraulic pump system to provide pressure fluid for operating the excavator unit 10. A cab 11 b is provided for the operator of the excavator unit 10. The excavator unit 10 includes an elongated boom 12 which is mounted on the platform 11 for pivotal movement in a generally vertical plane in a conventional manner. The boom 12 may be moved to selected working positions by one or more linearly extensible hydraulic cylinder actuators 13, one shown.
The excavator unit 10 includes a second boom 14 mounted for pivotal movement with respect to the first boom 12 at a pivot connection 14 a. Boom 14 is movable to selected working positions with respect to boom 12 by a hydraulic cylinder and piston actuator 16 of conventional design. Referring still further to FIG. 1, the boom 14 supports a unique hole digging device in accordance with the invention and generally designated by the numeral 20. The digging device 20 is supported on the distal end 15 of the boom 14 by spaced apart support arms 22, see FIGS. 3 and 4 also. Digging device 20 is operably connected to a third hydraulic cylinder and piston actuator 18 mounted on the boom 14 in a conventional manner including a clevis type mounting 14 c, FIG. 1, allowing for limited pivotal movement of actuator 18 with respect to boom 14.
In the illustrations of FIGS. 1 and 2, the hole digging device 20 of the present invention is shown mounted on the boom 14 in place of a conventional excavator bucket normally used with the excavator unit 10. In other words, an excavator bucket has been removed from being supported on the distal end 15 of boom 14 and also operably connected to the hydraulic cylinder and piston actuator 18, and the hole digging device 20 has been substituted for the aforementioned excavator bucket for performing operations to dig essentially vertical holes in the earth's surface 17. However, those skilled in the art will recognize that, by manipulating the boom 14 and the boom 12 with respect to the platform 11, the hole digging device 20 may be oriented for digging holes in various directions, depending on the topographic features of the earth formation being worked. For purposes of illustration in FIG. 1, the excavator unit 10 is shown on a generally flat horizontal surface 17, and the digging device 20 is oriented for digging a substantially vertical hole.
Referring to FIGS. 2, 3, and 4, a preferred manner of mounting the digging device 20 to the boom 14 is carried out by providing the spaced apart arms 22 with axially aligned pin receiving bores 23 and 25, respectively. Pin receiving bores 23 and 25 are adapted to receive respective cylindrical dowel pins 27, FIG. 3, which extend through cooperating bores 14 q in the boom 14, such bores being formed, for example, in spaced apart side plates 14 p of boom 14, as shown in FIG. 3. Pins 27 may be retained in their working positions shown by conventional means, not shown, such as cotter pins or the like, or by press fitting the pins in bores 23 and 25, or bores 14 q formed in boom 14. In this way, the digging device 20 may be conveniently supported on the distal end 15 of boom 14 in place of a conventional excavator bucket and also adapted for connection to the distal end 18 d of piston rod 18 e of hydraulic cylinder actuator 18, see FIG. 2. Piston rod distal end 18 d may be characterized as a pivot pin receiving boss for receiving a pin, not shown in FIG. 2, which pin is adapted to project into bores formed in support arms on one of two opposed digging blades of device 20 to be described further herein.
Referring now to the exploded perspective view of FIG. 4, the hole digging device 20 is further characterized by opposed generally arcuate digging blades 28 and 30 which, when connected to each other, form a substantially cylindrical cross-sectional profile, that is the digging blade 28 is approximately semi-circular in configuration and digging blade 30 is also approximately semi-circular, both with respect to central axis 21. Digging blade 28 is deliminted by a lower distal end 29 and digging blade 30 is delimited by a corresponding lower distal end 31. The wall thickness of both blades 28 and 30 may be scarfed or tapered toward ends 29 and 31 to assist in penetration of the blades into the earth. Digging blade 30 is shown to have tapered longitudinal edge portions 30 c and 30 d, for example, FIG. 4. As shown in FIG. 4, digging blade 30 is connected to lower extension parts 22 a of arms 22 in a suitable manner, such as by welding the extension parts to an inner surface 30 a of digging blade 30. Arms 22 are suitably spaced apart to match the spacing required by the width of the distal end 15 of boom 14, so that the arms 22 may be connected to the boom in the manner shown and described. Arms 22 may be scarfed at extension parts 22 a to fit arcuate blade surface 30 a.
Digging blade 28 is provided with spaced apart, preferably semi-circular, connecting bosses 32 and 34, FIG. 4, which project laterally with respect to the longitudinal extent of digging blade 28. Bosses 32 and 34 are provided with respective pivot pin receiving bores 32 a and 34 a as illustrated. Blade connecting bosses 32 and 34 are adapted to be received in corresponding recesses 36 and 38 formed in opposed upper side edges 40 and 42 of digging blade 30. Recesses 36 and 38 are closed at their intersection with inner surface 30 a of blade 30 by opposed bearing pin support plates 44 and 46, which plates may be welded to the inner wall surface 30 a of digging blade 30. Bearing pin support plates 44 and 46 are provided with respective pivot pin receiving bores 48 and 50, as illustrated in FIG. 4. Bores 48 and 50 are adapted to be aligned with bores 32 a and 34 a of digging blade 28 when bosses 32 and 34 are in registration with the recesses 36 and 38 of digging blade 30.
Digging blade 28 is provided with longitudinal opposed side edges 28 c and 28 d disposed generally below the bosses 32 and 34 and short longitudinal side edges 28 e and 28 f extending above the bosses 32 and 34 and terminating at an upper transverse edge 28 g of blade 28. Side edges 28 c and 28 d are disposed, preferably, at a slight acute angle with respect to longitudinal central axis 21 of digging device 20 so that a tapered or wedge shaped space is formed between edges 28 c and 30 c and between edges 28 d and 30 d when cooperating edges 28 e and 40 a are contiguous and when cooperating edges 28 f and 42 a are also contiguous or in contact with each other. In other words, edges 28 e and 28 f form a stop when engaged with edges 40 a and 42 a when blade 28 is pivoted with respect to blade 30, and comprising an open position of digging device 20.
Blades 28 and 30 are adapted to be connected to each other by respective bearing pins 52 and 54 each having respective cylindrical head portions 52 a and 54 a. Bearing pins 52 and 54 are cylindrical and are dimensioned to be received within cooperating bearing bushings 56 and 58 of digging device 20. Bushings 56 and 58 are adapted to be disposed in the cooperating bores 48 and 32 a and bores 50 and 34 a, respectively, for pivotally connecting the digging blades 28 and 30 to each other. Bearing bushings 56 and 58 may, for example, be press fitted into bores 32 a and 34 a. Pins 52 and 54 are adapted to project within the bores of the bearing bushings 56 and 58 and the heads 52 a and 54 a welded to the plates 44 and 46, respectively. In this way bearing pins 52 and 54 may pivot within the bearing bushings 56 and 58 as the digging plates 28 and 30 are pivoted with respect to each other for limited movement about a central axis of the coaxially aligned bores 48 and 50 of plates 44 and 46.
Referring further to FIG. 4, digging blade 28 is provided with spaced apart upwardly extending arms 62 suitably welded to arcuate inner surface 28 s of blade 28, and spaced apart approximately the same distance as the arms 22. Arms 62 are notched to fit above the major concave arcuate relieved portion of upper edge 28 g of blade 28 shown in FIG. 4. Arms 62 are interconnected by a suitable pivot pin 62 b operable to be connected to piston rod boss 18 d. Accordingly, digging blades 28 and 30 of device 20 are secured to each other for limited pivotal movement with respect to each other by the bearing pins 52 and 54 and the respective bearing bushings 56 and 58, which are secured in the bores 32 a and 34 a of digging blade 28, and are also in registration with the bores 48 and 50 of digging blade 30.
In response to actuation of the hydraulic cylinder actuator 18 to extend its piston rod 18 e, viewing FIGS. 1 and 2, digging blade 28 may undergo limited pivotal movement until surfaces or edges 28 c and 28 d engage edges 30 c and 30 d of the digging blade 30 to position the digging attachment 20 in a so-called closed position for lifting a quantity of earth out of a hole being formed by the digging device 20. Arcuate concave upper edge 28 g is provided to maintain cylindricity of a hole being formed by digging device 20 when the blades are moved to their closed positions prior to removal of a quantity of earth from a hole being dug. When actuator 18 is actuated to retract its piston rod 18 e upwardly, viewing FIGS. 1 and 2, digging blade 28 is pivoted with respect to digging blade 30 until edges 28 e and 28 f engage edges 40 a and 42 a thereby moving the blades 28 and 30 to a so-called open position with respect to each other and allowing dirt to fall out of the space between the blades. In a digging operation, the blades 28 and 30 are held in this open position as the booms 12 and 14 are manipulated to force the digging device 20 into the earth to penetrate same and retrieve a quantity of earth, this repeated operation being similar in some respects to a conventional manually operated post hole digging device.
The construction and operation of the digging device 20 is believed to be understandable to those skilled in the art based on the foregoing description. Conventional engineering materials may be used to form the components of the digging device 20, such as high strength steel for essentially all of the components except for the bearing bushings 56 and 58, which may be formed of a suitable compatible bearing material, such as bronze or even, possibly, a self lubricating polymer, such as nylon.
Although a preferred embodiment of a digging device for connection to an excavator boom has been described in detail herein, those skilled in the art will recognize that various substitutions and modifications may be made without departing from the scope and spirit of the appended claims.