Hydraulic hammer tools

Abstract

Disclosed herein is a tool for a hydraulic hammer (406) of a work machine (100). The tool includes a spline section (302) and a tool section (304). The spline section (302) includes a first spline sector (306) including at least six spline grooves (312) and a second spline sector (308) including at least six spline grooves (312). The first spline sector (306) and the second spline sector (308) are separated by a spacer (310). The tool section diameter (316) is 3.2 to 4.8 times larger than the spline groove diameter, and the tool section diameter (316) is smaller than the spline section (302) diameter.

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates generally to a hammer assembly for a work machine, and more particularly to a hammer tool of the hammer assembly. [Background technology]

[0002] Work machines, such as excavators, backhoes, skid steers, wheel loaders, and tractors, are provided with hammer assembly tools for breaking rock, concrete, soil material, or the like. Such hammer tools may be hydraulically driven, utilizing a hydraulic circuit supplied with fluid to operate the hammer assembly. Generally, hydraulic hammers include a piston that provides reciprocating motion to the tool for breaking rock, soil, concrete, or other material. The reciprocating piston may be driven by high-pressure fluid from the hydraulic system. The force of the reciprocating piston may be transmitted through the work tool to the material being broken.

[0003] Modern hammer assemblies typically use cylindrical bushings that are inserted into the hammer housing of the hammer assembly when the work tool is received therein. However, cylindrical bushings have the particular drawback of being often machined from solid stock, resulting in material waste. This, in turn, frequently results in high contact pressure and premature wear when the work tool contacts the bushing. Furthermore, bushings are often very large and heavy, making replacement and maintenance more difficult. Because the tool is part of the hydraulic hammer assembly through which the impact force of the hydraulic hammer is transmitted to the material, the tool and bushing can experience significant wear. Therefore, the tool may need to be replaced at the work site. There is also a need for the tool to function efficiently by reducing the stress on the work tool while reducing the frequency of component part replacement.

[0004] Other disclosures disclose tools for hydraulic hammer assemblies, but fail to provide a tool that is easily replaceable and that more uniformly controls stresses from the piston to achieve a longer service life. For example, U.S. Publication No. 2017136611 discloses a tool configured to couple with a hydraulic hammer. The tool includes an upper portion having a shaft with a plurality of upper grooves, a plurality of lower grooves, and circumferential recesses disposed between the plurality of upper grooves and the plurality of lower grooves, and a lower portion connected to the upper portion having a tool tip. The disclosure fails to disclose a tool that can control more uniform stress levels and reduce asymmetric bending due to operation of a work machine hammer assembly.

[0005] It can therefore be seen that a need exists for an improved work tool for hydraulic hammers on work machines in the field to improve efficiency, maneuverability, and versatility during installation, operation, and maintenance of the work machines. Summary of the Invention

[0006] According to one aspect of the present disclosure, a tool for a hydraulic hammer of a work machine is disclosed, the tool including a spline section and a tool section, the spline section including a first spline sector including at least six spline grooves and a second spline sector including at least six spline grooves, the first spline sector and the second spline sector being separated by a spacer, and the tool section diameter is smaller than the spline section diameter.

[0007] According to another aspect of the present disclosure, a hammer assembly is disclosed herein. The hammer assembly includes a hammer housing and a hammer tool. The hammer housing includes a hammer and a working chamber having a plurality of splines, a locking mechanism, and a retaining ring. The hammer tool is inserted into an opening in the hammer housing. The hammer tool has a spline section and a tool section, the spline section including a first spline sector including at least six spline grooves and a second spline sector including at least six spline grooves, the first spline sector and the second spline sector being separated by a spacer, and the tool section diameter is smaller than the spline section diameter.

[0008] According to another aspect of the present disclosure, a method for securing a hammer tool to a hammer assembly of a work machine is disclosed. The method includes: providing a hammer assembly including a hammer housing and a hammer tool, the hammer housing including a working chamber for receiving the hammer and the hammer tool through an opening in the hammer housing, the working chamber having a plurality of splines and a locking mechanism; providing a hammer tool having a spline section and a tool section, the spline section including a first spline sector including at least six spline grooves and a second spline sector including at least six spline grooves, the first spline sector and the second spline sector being separated by a spacer, the tool section having a smaller diameter than the spline sections; inserting the hammer tool into the working chamber through the opening in the hammer housing; and rotating the locking mechanism around the hammer tool until it is in a locked state.

[0009] These and other aspects and features of the present disclosure will be more readily understood from the following detailed description when read in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a perspective view of a work machine including a hammer assembly according to one embodiment of the present disclosure. [Figure 2] 2 is an enlarged perspective view of the hammer assembly of FIG. 1 connected to a boom of a work machine according to an embodiment of the present disclosure. [Figure 3] 3 is a perspective view of a hammer tool used in the hammer assembly of FIG. 2 according to an embodiment of the present disclosure. [Figure 4] 4 is a cross-sectional view of the hammer tool of FIG. 3 taken along line 4-4 of FIG. 3 and showing the working chamber of the hammer assembly, according to an embodiment of the present disclosure. [Figure 5] 5 is a cross-sectional view of the working chamber of FIG. 4 taken along line 5-5 of FIG. 4 according to an embodiment of the present disclosure. [Figure 6] FIG. 6 is a perspective view of a hammer tool connected to a hammer assembly with a working chamber shown in phantom lines according to an embodiment of the present disclosure. [Figure 7] FIG. 7 is a flowchart of a method for securing a hammer tool to a hammer assembly according to an embodiment of the present disclosure.

[0011] illustrates, by way of example only, one embodiment of the present invention. Those skilled in the art will readily recognize from the following discussion that alternative embodiments of the structures and methods described herein may be used without departing from the principles described herein. DETAILED DESCRIPTION OF THE INVENTION

[0012] Referring now to the drawings, and with particular reference to the illustrated embodiment, an exemplary work machine 100 is shown and illustrated as a backhoe loader. A backhoe loader is a heavy machine designed to move earth material from the ground or surface at construction and agricultural excavation sites. While the following detailed description describes exemplary aspects related to a backhoe loader, it will be understood that this description likewise applies to the use of the present disclosure in other work machines, including, but not limited to, excavators, front-end loaders, skid steers, wheel loaders, and tractors.

[0013] Referring to FIG. 1 , work machine 100 includes a frame 102 that supports an engine 104. Frame 102 is supported on ground engaging elements 106, illustrated as wheels. It should be envisioned that ground engaging elements 106 may be any other type of ground engaging element 106, such as tracks. Work machine 100 further includes a work mechanism 108 extending from the frame for performing work, such as breaking down earth, soil, concrete, rock, or other material at an excavation site. Frame 102 may be a rotating upper body common to excavators and work machines in agriculture, construction, and mining. Work mechanism 108 includes a boom 110, an arm 112, a bracket 114, and a hammer assembly 116. Hammer assembly 116 may be attached to work mechanism 108 via bracket 114. It may be appreciated that the hammer assembly 116 may also be attached to the work mechanism 108 via a coupler, quick coupler, or hydraulic quick coupler, as is commonly known in the art.

[0014] The hammer assembly 116 may be hydraulically actuated and connected to one or more hydraulic supply lines 118 via a hydraulic circuit (not shown) that includes the work machine 100. The hydraulic circuit may raise, lower, and / or pivot the arm 112 and boom 110, which correspondingly raises, lowers, and / or pivots the hammer assembly 116. The work machine 100 may include a pump (not shown) connected to the hydraulic circuit and the hammer assembly 116 through one or more hydraulic supply lines 118. The hydraulic circuit may conduct pressurized fluid, such as oil, from the pump through one or more hydraulic supply lines 118 to the cylinder and hammer assembly 116. Operator controls for moving and operating the hydraulic circuit and / or the hammer assembly 116 may be located in the cabin 120 of the work machine 100. A pressure control valve may be provided in the hammer assembly 116 to maintain maximum hydraulic pressure to ensure the hammer assembly 116 delivers all blows to fracture rocks and the like with maximum power.

[0015] 2, an enlarged view of the hammer assembly 116 connected to the arm 112 of the work machine 100 is shown. The hammer assembly 116 may include a hammer housing 200 and a hammer tool 202. The hammer tool 202 is connected to the hammer assembly 116 and is located within a working chamber 204 inside the hammer housing 200. The hammer tool 202 extends outside the hammer housing 200 on the opposite side of the bracket 114 for contacting and / or crushing rocks, dirt, soil, earth, and the like. The hammer housing 200 may be a symmetrical, reversible housing that can rotate 180 degrees to compensate for wear and extend the life of the hammer assembly 116.

[0016] 3 shows a perspective view of the hammer tool 202 used in the hammer assembly 116. The hammer tool 202 may include a shaft 300 including a spline section 302 and a tool section 304. The spline section 302 is generally the portion of the shaft 300 of the hammer tool 202 that is received by the hammer housing 200 within the working chamber 204 of the hammer assembly 116. Conversely, the tool section 304 of the shaft 300 may generally include the portion of the hammer tool 202 that protrudes from the hammer assembly 116 and contacts the material to be crushed. The spline section 302 has a larger diameter than the tool section 304.

[0017] The spline section 302 includes a first spline sector 306 and a second spline sector 308. The first spline sector 306 and the second spline sector 308 are separated by a spacer 310. The spacer 310 may be circular, square, octagonal, hexagonal, or polygonal in shape. The first spline sector 306 and the second spline sector 308 may each include a plurality of spline grooves 312 having a spline diameter 314. The spline grooves 312 of the first spline sector 306 may correspond and align with the spline grooves 312 of the second spline sector 308.

[0018] Each of the spline grooves 312 in the first spline sector 306 may align with a spline groove 312 in the second spline sector 308, and each may be hemispherical or curvilinear. Alternatively, each of the spline grooves 312 may be square, trapezoidal, or rectangular. The first spline sector 306 may include a corresponding number of spline grooves 312 in the spline sector 306 and the second spline sector 308. In one embodiment, the first spline sector 306 and the second spline sector 308 may each include between 6 and 12 spline grooves 312. For example, the first spline sector 306 may include between 6 and 12 spline grooves 312 and an equal number of spline grooves 312 in the second spline sector 308. Of course, other numbers of spline grooves 312 are possible. The spline grooves 312 may be located equidistantly around the circumference of the spline section 302 in both the first spline sector 306 and the second spline sector 308 .

[0019] The tool section includes a tool section diameter 316, which may be multiple times larger than the spline diameter 314. For example, the tool section diameter 316 may be 3.2 to 4.8 times larger than the spline diameter 314, although these are illustrative ranges. The first spline sector 306 and the second spline sector 308 may have a larger diameter than the tool section diameter 316. The larger diameters of the first spline sector 306 and the second spline sector 308 distribute stress over a larger contact area, thereby reducing bending stress in the hammer tool 202. Furthermore, when the spacer 310 is configured as a rounded center shape without a tool pin notch, the spacer transfers less stress through the hammer tool 202. In one embodiment, the hammer tool 202 may include a tool tip 318. The tool tip 318 may be a chisel point, moil point, cone point, spade, compaction plate, wedge, or other tool shape commonly known in the art for breaking up rock, soil, or other materials.

[0020] 4 provides a cross-section of the hammer tool 202 of FIG. 3 taken along line 4-4 of FIG. 3 and showing the working chamber 204 of the hammer assembly 116, in one embodiment of the present disclosure. The working chamber 204 includes a first set of splines 400 and a second set of splines 402 separated by a locking mechanism 404. The locking mechanism 404 may also be commonly referred to as a "tool stop" and may be configured as a ring positioned around the spacer 310 of the hammer tool 202.

[0021] The first set of splines 400 corresponds to the spline grooves 312 of the first spline sector 306, and the second set of splines 402 corresponds to the spline grooves 312 of the second spline sector 308 on the hammer tool 202. The first set of splines 400 and the second set of splines 402 may be coaxial or otherwise aligned. There may be between 6 and 12 splines in each of the first set of splines 400 and the second set of splines 402, although other numbers of splines are possible. The first set of splines 400 and the second set of splines 402 may be wear rods that are cylindrical rods, square rods, or polygonal rods.

[0022] 4 shows, in one embodiment, the hammer tool 202 operably coupled to a hammer 406 within the hammer housing 200, whereby the hammer 406 is positioned above the splined section 302 of the hammer tool 202. The hammer 406 may be a piston or other type of hammer that provides a reciprocating impact motion to the hammer tool 202, as is commonly known in the art.

[0023] A hydraulic circuit within the work machine 100 may be operatively connected to the hammer assembly 416 and may provide pressurized fluid to cause the hammer 406 to alternately reciprocate in an actuation stroke pattern and a return stroke pattern, as commonly known in the art. Operator controls for movement of the work mechanism 108 and / or the hammer assembly 116 may be located within the cabin 120 of the work machine 100. The hammer inside the hammer housing 200 may be powered by a hydraulic supply and provide a reciprocating impact motion to the hammer tool 202, which may in turn be applied to material, such as rock or concrete, that contacts the hammer tool 202. It is envisioned that the hammer tool 202 may include any known tool capable of interacting with the hammer 406 and the ground, rock, or other material. The tool section 304, or portions thereof, may move in and out of the hammer housing 200 during operation, such as when the hammer provides a reciprocating impact motion to the hammer tool 202.

[0024] There may be a thrust ring 408 around the connection point where the hammer 406 contacts the hammer tool 202. There may also be a retaining ring 410 located at the end of the second set of splines 402 opposite the locking mechanism 404 to retain the first set of splines 400 and the second set of splines 402 within the hammer assembly 116.

[0025] Referring now to FIG. 5, a cross-sectional view of the working chamber 204 taken along line 5-5 of FIG. 4 is shown in one embodiment. The locking mechanism 404 can be configured to couple the hammer tool 202 within the hammer assembly 116. The locking mechanism 404 surrounds the spacer 310 of the hammer tool 202. The interior surface of the locking mechanism 404 that contacts the spacer 310 can include a plurality of locking recesses 500 protruding from the locking mechanism 404. The plurality of locking recesses 500 can be shaped as a pyramid, trapezoid, square, etc., with the spacer 310 configured to receive the plurality of locking recesses 500. When the plurality of locking recesses 500 align with the first set of splines 400 and / or the second set of splines 402, the hammer tool 202 is in an unlocked state with the hammer assembly 116. The hammer tool 202 can be easily removed from the hammer assembly 116 for repair when the locking mechanism 404 is in the unlocked state.

[0026] While the locking mechanism 404 is in the unlocked state, the replacement hammer tool 202 can be inserted into the working chamber 204 of the hammer assembly 116. When the locking mechanism 404 is rotated such that the plurality of locking recesses 500 are not aligned with the first set of splines 400 and / or the second set of splines 402, the hammer tool 202 is in a locked state with the hammer assembly 116.

[0027] Referring now to FIG. 6 , a perspective view of the working chamber 204 is shown in one embodiment. The first set of splines 400 and the second set of splines 402 are shown as rounded, which is most efficient for the machining process. The first set of splines 400 and the second set of splines 402 may be small enough to be handled by hand. The additional surface area of ​​the first set of splines 400 and the second set of splines 402 spreads the contact stress of the hammer 406 with the hammer tool 202 among several splines. One or more of the splines may be easily replaced and / or reused. The first set of splines 400 and the second set of splines 402 may be the same rod, which reduces the number of parts required and thereby provides simplified part storage and replacement.

[0028] The first set of splines 400 and the second set of splines 402 allow the hammer tool 202 to rotate in the event of chip damage or wear and tear of the tool tip 318 without requiring specific parts for the particular chisel angle orientation needed to fracture rock, soil, or the like. For example, as shown in FIG. 6 , the tool tip 318 can be shaped as a wedged chisel tip that can be rotated so that the surface of the tool tip 318 can be at a preferred angle when contacting rock, soil, or other material during operation of the hammer assembly 116. [Industrial Applicability]

[0029] Once in effect, the present disclosure may find applicability in many industries, including, but not limited to, construction, civil engineering, mining, and agriculture. Specifically, the techniques of the present disclosure may be used to break up various materials, such as rock, concrete, asphalt, or other earth materials, in various work machines, including, but not limited to, shovels, backhoes, skid steers, wheel loaders, tractors, etc. Although the foregoing detailed description is made with particular reference to backhoe loaders, it should be understood that the teachings thereof may also be applied to other work machines that utilize a hammer assembly, such as, for example, shovels, skid steers, wheel loaders, tractors, mulchers, etc.

[0030] 1-6 , the industrial applicability of the hammer tool 202 configured to couple to the hammer assembly 116 described herein will be readily understood from the foregoing discussion. According to some embodiments, the hammer assembly 116 and the hammer tool 202 may each be configured to facilitate quick, low-effort coupling and / or decoupling of the hammer tool 202 with the hammer assembly 116. For example, because the hammer tool 202 is used to break hard materials such as rock, the hammer tool 202 may experience significant wear and may require quick replacement at the job site with a new hammer tool 202 and easier maintenance.

[0031] Additionally, a hammer tool 202 configured with one type of tool tip 318 (e.g., a chisel point) may be replaced with another hammer tool 202 with a different type of tool tip 318 (e.g., a compaction plate) according to the requirements of the job site and the material that needs to be crushed.

[0032] While the locking mechanism 404 is in the unlocked state, the hammer tool 202 can be inserted into the working chamber 204 of the hammer assembly 116. When an operator inserts the hammer tool 202 into the working chamber 204 of the hammer assembly 116, the locking mechanism 404 can be rotated to a locked state in which the hammer tool 202 is securely coupled with the hammer housing 200. The operator can rotate the locking mechanism 404 to the locked state. In the locked state, the spline grooves 312 of the first spline sector 306 are not aligned with the locking recesses 500, and therefore, the locking recesses 500 are also not aligned with the first set of splines 400 and the second set of splines 402. Due to the misalignment, the hammer tool 202 can be retained within the working chamber 204 of the hammer assembly 116 and therefore operably coupled with the hammer housing 200.

[0033] 7, a method 700 of securing a hammer tool 202 to a hammer assembly 116 of a work machine 100 is disclosed. In a first step 702, a hammer assembly 116 is provided having a hammer housing 200 and a hammer tool 202, the hammer housing 200 having a working chamber 204 for receiving a hammer 406 and the hammer tool 202 through an opening in the hammer housing 200, the working chamber 204 having a first set of splines 400, a second set of splines 402, and a locking mechanism 404. In step 704, the hammer tool 202 is configured with a spline section 302 and a tool section 304, where the spline section 302 includes a first spline sector 306 having at least six spline grooves 312 and a second spline sector 308 having at least six spline grooves 312, the first spline sector 306 and the second spline sector 308 being separated by a spacer 310, and the tool section 304 has a smaller diameter than the spline section 302. In step 706, the hammer tool 202 is inserted into the working chamber 204 through the opening in the hammer housing 200. In a final step 708, the locking mechanism is rotated around the hammer tool until it is in a locked state.

[0034] From the above, it can be seen that the technology disclosed herein has industrial applicability in a variety of situations, such as, but not limited to, construction, mining, and agricultural work machines that utilize a hammer assembly with a work tool for breaking up rock, soil, or other materials.

Claims

1. A tool for a hydraulic hammer (406) of a work machine (100), comprising: a spline section (302) including a first spline sector (306) including at least six spline grooves (312) and a second spline sector (308) including at least six spline grooves (312), wherein the first spline sector (306) and the second spline sector (308) are separated by a spacer (310); a tool section (304) having a tool section diameter (316), said tool section diameter (316) being smaller than a spline section (302) diameter.

2. the spline section (302) includes 6 to 12 spline grooves (312) in the first spline sector (306) and 6 to 12 spline grooves (312) in the second spline sector (308), and the tool section diameter (316) is 3.2 to 4.8 times larger than the spline groove diameter; the spacer (310) has a smaller diameter than the first spline sector (306) and the second spline sector (308), and the spacer (310) is configured to be circumferentially, square, octagonally, or polygonally shaped; 2. The tool of claim 1, wherein the tool section (304) includes a tool tip (318) opposite the spline section (302), the tool tip (318) being selected from the group consisting of a chisel point, a moil point, a conical point, a spade, a compaction plate, and a wedge.

3. 2. The tool of claim 1, wherein the at least six spline grooves (312) in the first spline sector (306) are aligned with the at least six spline grooves (312) in the second spline sector (308).

4. 2. The tool of claim 1, wherein the at least six spline grooves in the first spline sector and the at least six spline grooves in the second spline sector are configured to receive a cylindrical rod, a conical rod, a square rod, or a polygonal shaped rod, and the at least six spline grooves in the first spline sector have diameters that match or are different from the diameters of the at least six spline grooves in the second spline sector.

5. A hammer assembly (116) comprising: Hammer (406) and a hammer housing (200); A working chamber (204) in the hammer housing (200) having a plurality of splines (400), a locking mechanism (404), a retaining ring, and a hammer tool (202) inserted into the working chamber (204) within an opening in the hammer housing (200), the hammer tool (202) including a spline section (302) and a tool section (304), the spline section (302) including a first spline groove (312) having at least six spline grooves (312). a working chamber (204) including a tool section (304) having a tool section diameter (316), the tool section diameter (316) being smaller than the spline section (302) diameter; and a second spline sector (308) including at least six splines (400), the first spline sector (306) and the second spline sector (308) being separated by a spacer (310).

6. a locking mechanism (404) separating a first set of splines and a second set of splines, the first set of splines having 6 to 12 splines (400) and the second set of splines having 6 to 12 splines (400); the first spline sector (306) having 6 to 12 spline grooves (312) configured to receive the first set of splines; and the second spline sector (308) having 6 to 12 spline grooves (312) configured to receive the second set of splines. the tool section diameter (316) being 3.2 to 4.8 times greater than the spline groove diameter; the hammer assembly (116) is hydraulically driven; The hammer assembly (116) of claim 5, wherein the hammer tool (202) is freely rotatable.

7. the locking mechanism (404) is a ring having a locking recess (500) disposed across an interior of the locking mechanism (404) and configured to rotate around the spacer (310) from a locked state and an unlocked state, whereby the locked state couples the hammer tool (202) to the hammer housing (200); the locking recess (500) is selected from the group consisting of a pyramid, a square, and a trapezoid; 7. The hammer assembly of claim 6, wherein the tool section includes a tool tip opposite the spline section, the tool tip being selected from the group consisting of a chisel point, a moil point, a conical point, a spade, a compaction plate, and a wedge.

8. 8. The hammer assembly of claim 7, wherein the plurality of splines are wear rods, the first set of splines are conical wear rods, and the second set of splines are polygonal wear rods, whereby the first spline sector and the second spline sector are each configured to receive the first set of splines and the second set of splines, respectively.

9. 8. The hammer assembly of claim 7, wherein the first set of splines received by the first spline sector of the hammer tool are axially aligned with the second set of splines received by the second spline sector of the hammer tool.

10. The hammer assembly (116) is connected to a bracket (114) of the work machine (100), and the work machine (100) A frame (102); ground engaging elements supporting said frame (102); an engine (104) within the frame (102) for powering the work machine (100); a working mechanism (108) extending from the frame (102); A hydraulic circuit; The hammer assembly (116) of claim 9, comprising: said bracket (114) on an end of said working mechanism (108).

11. A method (700) for securing and maintaining a hammer tool (202) to a hammer assembly (116) of a work machine (100), comprising: providing the hammer assembly (116) including a hammer housing (200) and the hammer tool (202), the hammer housing (200) including a working chamber (204) for receiving a hammer (406) and the hammer tool (202) through an opening in the hammer housing (200), the working chamber (204) having a plurality of splines (400) and a locking mechanism (404); Configuring the hammer tool (202) to have a spline section (302) and a tool section (304), wherein the spline section (302) includes a first spline sector (306) having at least six spline grooves (312) and a second spline sector (308) having at least six spline grooves (312), the first spline sector (306) and the second spline sector (308) being separated by a spacer (310), and the tool section (304) having a smaller diameter than the spline section (302); inserting the hammer tool (202) through the opening in the hammer housing (200) into the working chamber (204); and rotating the locking mechanism (404) about the hammer tool (202) until the locking mechanism (404) is in a locked state.

12. The method (700) operating the hammer assembly (116) against the earth material until the hammer tool (202) is worn; rotating the locking mechanism (404) around the hammer tool (202) until it is in an unlocked state; removing the hammer tool (202) from the working chamber (204) through the opening and out of the hammer housing (200); Inserting a replacement hammer tool (202) through the opening in the hammer housing (200) and into the working chamber (204); and 12. The method (700) of claim 11, further comprising rotating the locking mechanism (404) about the replacement hammer tool (202) until it is in a locked state.

13. The method (700) operating the hammer assembly (116) against the earth material with the tool tip (318) of the hammer tool (202) until the tool tip (318) is chipped; and 12. The method (700) of claim 11, further comprising rotating the hammer tool (202) so that the tool tip (318) is in a preferred position for contacting the earth material during operation of the hammer assembly (116).

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