Ground engaging tool retention system

[0001] The field of this invention is ground engaging tools, and more specifically systems for retaining ground engaging tools on buckets, blades, and other work tools.

[0002] Many construction and mining machines, such as excavators, wheel loaders, hydraulic mining shovels, and draglines employ buckets to dig material out of the earth. The abrasion and impacts experienced during digging subject the buckets to extreme wear. In addition to buckets, other construction and mining machines, such as bulldozers, motor graders, and scrapers, employ blades or other types of earth-working tools to move soil and rock. Like buckets, these blades and other types of earth-working tools also experience extreme wear through abrasion and other mechanisms.

[0003] Buckets, blades, and other earth-working tools can be protected against this wear by including ground engaging tools (GET). GET is typically fashioned as teeth, edge protectors, sidebar protectors, wear plates, etc. which are attached to the bucket or blade in the area where the most damaging abrasion and impacts occur. The GET includes sacrificial wear material that will gradually wear away as it scrapes against the soil and rocks. For example, the cutting edge of a bucket can be protected with edge protectors, one type of GET, that wrap around and protect the edge.

[0004] The GET can be removed when it has been worn and replaced at a reasonable cost with new GET to continue to protect the bucket, blade, or other earth-working tool. Large buckets for draglines and hydraulic shovels can cost a considerable amount, so protecting them against wear is important. It is more economical to wear out and replace the GET than to wear out and replace an entire bucket.

[0005] Besides protection against wear, another purpose of GET may be to provide more effective digging. A tooth mounted on the edge of a bucket, for example, may allow the bucket to penetrate into the soil or rock and dig more effectively with less effort. A tip mounted on the wheel of a trash compactor machine will grind and compress garbage so it occupies less space in a landfill.

[0006] Owners and operators of these construction and mining machines, and the technicians who maintain and repair them, expect that the GET will remain attached to the machine during use, but that it will also be easily and quickly removable when it is worn and needs replacement. A retention system performs the job of reliably holding the GET on the machine during use, then permitting easy and quick detachment during service.

[0007] Many retention systems have been proposed and used for removably attaching GET to buckets, blades, and other earth-working tools. One common type of retention system produced by several manufacturers includes a shear pin which holds the GET onto an adapter or base. One example of this type of shear pin system is shown in U.S. Pat. No. 5,009,017 issued Apr. 23, 1991.

[0008] Problems can exist with these known systems. For example, installing the shear pin may require a hammer to drive the pin into the bore formed in the GET and the adapter. On large GET systems, the hammer required to drive in the pin may likewise be very large, and swinging such a large hammer in difficult field conditions can be objectionable to the technician. Sometimes the spacing of teeth on the edge of a bucket does not provide a comfortable amount of space between the teeth to swing the hammer and drive the shear pins.

[0009] As an example of another problem or shortcoming with these known retention systems, the shear pin may “walk” out of the bore and unintentionally release the GET from the adapter. The retention system must be very secure and not permit the GET to fall off of the bucket, blade or other earth-working tool, even when the GET is worn extensively. If the GET falls off, it could be fed into a crusher or other processing machine and cause damage. Missing GET can result in extensive wear and damage of the bucket, blade, or other earth-working tool if the missing GET is not immediately detected and replaced. Other problems may also occur if the GET unintentionally falls off the bucket. The known retention systems have not always held the GET to the bucket or other work tool with adequate reliability.

[0010] In general, the proposed and known retention systems leave room for improvement. This invention provides several improvements.

[0011] According to one embodiment of the invention, a retainer assembly may include a pin elongated in the direction of a longitudinal axis, the pin being generally cylindrical in shape with an outer, cylindrical surface, a first axial end, and a second axial end opposite the first axial end, the first axial end having a threaded bore formed therein, and the second axial end having means for connecting to a tool to apply torque to the pin. The retainer assembly may also include a generally annular-shaped washer having a central bore, an axial first end, and an axial second end opposite the axial first end, a bolt having a threaded shank and a head, and the head having means for connecting to a tool to apply torque to the bolt. The diameter of the washer may be greater that the diameter of the cylindrical surface of the pin and the diameter of the head of the bolt. The threaded shank of the bolt may pass through the central bore of the washer, and thread into the threaded bore of the pin.

[0012] According to another embodiment of the invention, a method of attaching a ground engaging tool to a work machine, the adapter being attached to a work machine, the method may comprise positioning a washer in a pocket formed on one of the tip or the adapter, sliding the tip over a portion of the adapter in a sliding direction so that the washer is trapped and not removable from between the tip and the adapter in the pocket, sliding the tip further in the sliding direction over the portion of the adapter until a first bore formed in the tip aligns with a second bore formed in the adapter, inserting a pin into the first and second bore such that the pin prevents the tip from being slid in a direction opposite the sliding direction off of the adapter, and attaching a bolt with a shank to the pin, the shank passing through a central bore in the washer, and the shank being threaded and engaging a threaded bore in the pin.

[0013] FIG. 1 is an isometric view of a retainer assembly.

[0014] FIG. 2 is an isometric exploded view of the retainer assembly of FIG. 1.

[0015] FIG. 3 is a side plan view of the retainer assembly of FIG. 1.

[0016] FIG. 4 is a front view of the retainer assembly of FIG. 1.

[0017] FIG. 5 is a back view of the retainer assembly of FIG. 1.

[0018] FIG. 6 is a sectional view of the retainer assembly of FIG. 1 being installed with a GET tip and adapter system.

[0019] FIG. 7 shows the retainer assembly and tip and adapter system of FIG. 6 in a fully installed state, the retainer assembly acting to retain the tip on the adapter.

[0020] FIG. 8 shows an alternate embodiment of a retainer assembly installed on a GET tip and adapter system.

[0021] A principal exemplary embodiment which illustrates the principles of the invention will be described below. The exemplary embodiment is shown in FIGS. 1-7. By showing a single principal embodiment, however, it is not intended that the scope of patent protection be limited to this embodiment only. Those of skill in the art will be able to adapt the inventive principles taught herein to construct other embodiments of an inventive retainer system, and it is intended that these other embodiments also be included in the scope of patent protection, as defined by the appended claims.

[0022] With reference first to FIGS. 1 and 2, the exemplary retainer assembly 10 includes three components: a pin 20, a washer 30, and a mechanical fastener such as bolt 40. FIG. 1 illustrates the pin 20, washer 30, and bolt 40 in an assembled state, while FIG. 2 illustrates them in an exploded view.

[0023] The pin 20 is elongated in a longitudinal direction running from a first end 21 to a second end 22. The pin may be generally cylindrical in shape with an outer, cylindrical surface 23, with the first end 21 and opposite second end 22 forming the opposite, axial ends of the cylinder. The first end 21 may include a threaded bore 24. A chamfer 26 can be provided between the threaded bore 24 and the first end 21. The second end 22 may include a socket 25 for allowing a tool to rotate the pin 20 (see FIG. 5 for the socket 25 which will be further described below).

[0024] Washer 30 is generally annular in shape, with a central bore 31, an axial first end 32 and an axial second end 33 opposite the first end. Central bore 31 may include a tapered portion 34 where the inside diameter of the bore increases along the axis thereof approaching the second end 33. The radial exterior surface 37 of washer 30 may also include rounds or chamfers 35 and 36 between the radial exterior surface 37 and the first and second ends 32 and 33 (see FIG. 3).

[0025] Bolt 40 includes a shank 41 which is threaded to match threaded bore 24 of pin 20. A head 42 attaches to the shank 41. Head 42 may include a socket 43 for receiving a driving tool, such as an impact wrench or torque wrench. The underside of the head 42 may include a tapered portion 44 (see FIG. 6) extending between the head 42 and the shank 41, whose taper angle generally corresponds to the taper angle of tapered portion 34.

[0026] When the retainer assembly 10 is assembled, the shank 41 of bolt 40 passes through the central bore 31 of washer 30. The shank 41 further threads into the threaded bore 24 of pin 20. Tapered portions 34 and 44, if included, will abut one another, and first end 32 of washer 30 will abut first end 21 of pin 20. As the torque on bolt 40 relative to pin 20 is increased, the tapered portions 34 and 44 will direct the compressive stress between bolt 40 and pin 20 into hoop stress in the washer 30. The resulting strain will help lock together the three components, the bolt 40, washer 30, and pin 20, so that vibrations will not cause them to unintentionally disengage.

[0027] FIG. 3 shows the assembled retainer assembly 10 in a side view. FIGS. 4 and 5 illustrate front and back views of the assembled retainer assembly 10. In FIGS. 4 and 5, the sockets 43 and 24 are visible. These sockets may take any desirable form to match a tool to be used in the assembly process. One way to torque the retainer assembly 10 together would be to use a socket wrench in socket 24 to provide back torque to the pin 20, while using an impact wrench in socket 43 to apply torque to the bolt 40 relative to the pin 20. However, other arrangements are possible and can be adopted depending upon the type of tool that is desired for the assembly. For example, protrusions may be provided instead of sockets so that an open-end or closed-end wrench may apply torque to the pin 20 and bolt 40. Also, the pin 20 may be shaped such that it will not turn when assembled inside of a GET adapter, obviating the need for the back torque applied to socket 24.

[0028] FIG. 6 illustrates the retainer assembly 10 with an adapter 50 and a replaceable wear tip 60 (shown only partially). GET systems with an adapter or base attached to the machine (such as to the bucket or blade) and a replaceable wear member, such as tip 60, attached to the adapter are well known to those of skill in this art. The exemplary adapter 50 and tip 60 are representative of the many different structures which the retainer assembly 10 could hold together. For example, tip 60 could be a tip on a compactor wheel with adapter 50 welded to the circumferential surface of the wheel. Or, tip 60 could be an edge protector for a bucket, with adapter 50 attached to the bucket edge, or adapter 50 representing the bucket edge itself. Or, as illustrated, tip 60 may be a replaceable ground engaging tooth and the adapter 50 may be mounted to a bucket.

[0029] Adapter 50 includes a nose portion 51 which fits into a pocket 61 formed in the tip 60. The tip 60 slides onto the nose portion 51 of the adapter 50 in a sliding direction indicated by the arrow in FIG. 6. The nose portion 51 and pocket 61 are typically shaped so that they fit closely together, with little or no appreciable movement possible between the adapter 50 and the tip 60 when they are assembled.

[0030] In FIG. 6, the washer 30 has been placed in a pocket 52 formed in the adapter 50. Alternatively, a pocket for the washer 30 may be formed in the tip 60. The pocket 52 is formed on the adapter 50 at the opening of a through bore 53. In the illustrated example, the pocket 52 is a counterbore with a diameter larger than the diameter of the bore 53.

[0031] The washer 30 remains in pocket 52 while the tip 60 slides onto the nose portion 51. When the tip 60 is slid to a certain extent onto the nose portion 51, the tip traps the washer 30 in the pocket 52 so that it is between the tip and the adapter 50 and cannot be removed.

[0032] When the tip 60 slides further onto the nose portion 51 so that it fits snugly into the pocket 61, a bore 62 formed on the tip will align with the bore 53 on the adapter 50. This is illustrated in FIG. 7. At this point, the washer 30 continues to be trapped in the pocket 52. The washer 30 cannot pass through bores 53 or 62 because the diameter of the washer is greater than their diameters.

[0033] The pin 20 may then be inserted in one side of the aligned bores 53 and 62 until its first end 21 abuts the first end 32 of washer 30. The bolt 40 may also be inserted in the opposite end of aligned bores 53 and 62. The shank 41 passes through the central bore 31 of washer 30, and engages the threaded bore 24 of pin 20. Tapered portion 44 and chamfer 26 can help align the bolt 40 with the central bore 31 and the threaded bore 24. The pin 20 and the bolt 40 are torqued relative to one another until tapered portion 44 contacts tapered portion 34 of washer 30. Further torquing will lock the pin 20, washer 30, and bolt 40 together so that they will not release unless an opposite releasing torque is applied. In FIG. 7 it can be seen that the tapered portion 44 and the tapered portion 34 may be positioned and sized so that when the bolt 40 is assembled with the washer 30 in the central bore 31, the head 40 does not protrude axially any further than second end 33.

[0034] Once the pin 20, washer 30, and bolt 40 are attached, the retainer assembly 10 cannot be removed from the adapter 50 or tip 60 because the diameter of the exterior radial surface 37 of washer 30 is too great to pass through bores 53 or 62. However, the diameter of the cylindrical surface 23 and the diameter of the head 42 of bolt 40 may each be less than, the diameter of bore 52 and/or the diameter of bore 63 so that the pin 20 and bolt 40 can pass through these bores. By implication, the diameter of exterior radial surface 37 is greater than the diameter of head 42 and cylindrical surface 23.

[0035] Also, the pin 20 is positioned both in bore 62 of tip 60 and bore 53 of adapter 50. Pin 20 acts as a shear pin to block tip 60 from being removed from adapter 50.

[0036] FIG. 8 illustrates an alternate embodiment of retainer assembly 10. In FIG. 8, the washer 30 and bolt 40 have been combined into a single part, end cap 70. In likewise fashion, end cap 70 is trapped in pocket 52 and includes a shank 41 which threads into the threaded bore 24 of pin 20 during installation.

[0037] The pin 20, washer 30, and bolt 40 may each be made from steel for strength and durability, and optionally from stainless steel so that they will not deteriorate in the damp and difficult conditions they will experience in the field.

[0038] The retainer assembly 10 disclosed above may be used in industry to retain a ground engaging tool onto a work machine. The assembly 10 provides certain advantages over prior art systems. For one, a hammer is not necessary to install the system 10. Some prior art systems required the technician to swing a large hammer in order to drive a shear pin between the tip and adapter. The system 10 can be applied more conveniently, but still only requires simple hand tools. The torque between the bolt 40 and pin 20 creates a tight, reliable attachment that will not unintentionally release due to vibrations or other loads. And finally, the pin 20 is strong and can reliably retain the tip or other GET onto the adapter or other part of the machine without breaking.