AU655449B2

AU655449B2 - Shear pin assembly

Info

Publication number: AU655449B2
Application number: AU10612/92A
Authority: AU
Inventors: Allan James Yeomans
Original assignee: Individual
Current assignee: Individual
Priority date: 1992-02-03
Filing date: 1992-02-03
Publication date: 1994-12-22
Anticipated expiration: 2012-02-03
Also published as: FR2689942B1; NZ245792A; GB9301922D0; FR2689942A1; GB2264619B; GB2264619A; AU1061292A

Description

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r* r I I 655449 P/:00/011 Regulation 3.2

AUSTRALIA

Patents Act 1990 a P L E E C O M P L E T E SPECIFICATION 0 0 Q o Q o aB O0OG

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0000 en t 9, e t lil Is e11 DIti FOR A STANDARD PATENT

ORIGINAL

TO BE COMPLETED BY APPLICANT ALLAN JAMES YEOMANS ALLAN JAMES YEOMANS JOHN R.G. GARDNER, PO BOX 443, MUDGEERABA QLD 4213 Name of Applicant: Actual Inventor(s): Address for Service: 4:1 0Lk~L; Invention title: SHEAR PIN ASSEMBLY The following statement is a full description of this invention, including the best method of performing it know to me:- 2 Technical Field The present invention relates to a shear pin connection assembly particularly but not exclusively applicable to a shank or tine mounting assembly for the attachment of earth working shanks or tines to cultivator frames or tool bars.

Background Art Seedbeds for agriculture and foundations for construction sites are typically prepared by forcing strong metal shanks or tines through the compacted soil. The shanks are mounted to a cultivator frame that is pulled by a tractor through a drawbar or mounted to a tool bar that is attached to a tractor by means of a three point hitch.

It has been common for the attachment of the shanks to the frames to be such that the shanks can be shifted laterally to permit mounting at different lateral spacings between shanks. It has also been common for the shanks to be releasably mounted to prevent damage to the shanks, frame, tool 4 t bar, and/or the shank carrying implement when an obstruction is encountered in the soil.

Typically, shanks have also been mounted in such a manner that the shank (and in particular its actual ground engaging point) vibrate so as to reduce drag through the soil and also to produce better fracturing of the soil being cultivated. Therefore, the shank has usually been rigidly attached to the frame so as to inhibit the dampening of vibrations from the tractor and those generated by the tilling process.

Various structures have been used to attach shanks to a cultivating frame. One common configuration has been the use 30 of a clamping member with an upper end clamped or bolted to the frame, where a shank member is secured in a yoke in the clamping member lower end by a suitable mounting pin or bolt and a suitable shear pin extending through two sets of aligned holes in the yoke and shank member. However, because of the inherent clearance between the bolt and the respective holes in the yoke and the shank member, this structure does not form a rigid attachment to the frame member, and therefore the L.

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4 C, vibrations transmitted to the ground working point of the shank are undesirably dampened. Further, the pins also require some form of restraint to prevent them from working out of position in use. Still further, since shear pins tend to bend and distort during the shearing process and when the shearing action is completed, the sheared portion of the shear pin is often difficult to remove from the holes in the yoke and the shank member. In order to reduce this difficulty in removing the distorted shear pin components, shear pins sometimes have had grooves machines into them at the point where shearing is desired to occur. However, such machining adds to the cost of the shear pin and, since the size of the radii of such grooves is critical to the force required to shear the pins (the smaller the radii the lower the shear force required), the unavoidable variation in the radii of such grooves reduces the predictability of the required clearing force (that is, such grooved shear pins have undesirably unpredictable failure).

Another common configuration has been to rigidly attach the shank directly to the frame of the implement or the tool bar by positioning the shank against the frame and then bolting a clamp member to the shank and about the frame, whereby the bolts will thereafter fail in tension should an obstruction be encountered. In one variation of that structure, the nuts attached to the bolts are of softer mai., ial so that, when an obstruction is encountered by the shank, it is the nut which fails (by stripping the internal thread of the nut) and thus the bolt is not damaged and may be reused. This configuration does generally tend to rigidly connect the frame and shank so as co transfer vibrations through to the ground working point 30 as desired. However, refitting new bolts or nuts in a farm field after each failure occurs is often difficult and time consuming for a number of reasons. First, the soft nut material may smear into the threads of the reused bolt so that threading a new nut on the reused bolt can be difficult.

Second, the torque to be applied to the nut during reinstallation of the shank member must be sufficient to adequately secure the shank member but not too great to cause i 4

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i 4 stripping of the soft nut or failure of a soft bolt. Of course, obtaining this proper torque is particularly difficult if smeared metal remains on the reused bolt.

It is the object of the present invention to overcome and substantially ameliorate the above described disadvantages and to enhance the usefulness of such systems in the field.

Summary of the Invention In one aspect, the present invention provides a soil penetrating tool assembly for mounting to a tool bar of a soil penetrating implement comprising: a shank member having an elongate body, a soil penetrating tool located on a first end of said body, and a facing plate located on a second end of said body, said facing plate engaging one side of said tool bar when H mounted to said tool bar, said facing plate having a first d end and a second end, said facing plate second end having a facing plate opening with a first selected transverse 2dimension; S 20 a clamping plate engaging another side of the tool bar when mounted thereto, said clamping plate having a first end and a second end, said clamping plate second end having a clamping plate opening extending therethrough said clamping plate opening having two sections offset from one another with different centre lines with portions of each of said section being aligned to define a -enerally cylindrical passage therethrough having a selected diameter; said openings in said facing plate and clamping plate having axes extending substantially parallel to said tool bar when said facing and clamping plates are mounted to said tool bar; means for securing said facing plate first end to said clamping plate first end; and a substantially cylindrical shear pin having a diameter slightly less than the selected diameter and extending through the defined passage in the clamping plate l- opening and through the facing plate opening when said

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shank member is mounted to said tool bar.

In another aspect of the present invention, the clamping plate first end and the facing plate first end include facing flanges each having a through hole and a bolt secures the flanges together with a clearance therebetween so that upon failure of the shear pin the shank member and clamping plate may pivot about the bolt and clear of the -tool bar to allow movement of the shank member about the tool bar.

In yet another aspect of the present invention, the clamping plate second end ie forked with two prongs and the facing plate second end is disposed between the prongs.

The clamping plate opening in both of the prongs includes two sections offset from one another with different centre lines, and the aligned portions of the opening sections in each of the prongs define the generally cylindrical passage.

One of the clamping members is secured to or formed integrally with the shank member. The first interconnecting means preferably comprises a pivotal interconnection.

In still another aspect of the present invention, the longitudinal openings are generally oblong in crosssection.

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In a further aspect, the present invention provides a shear pin connection assembly for interconnecting a pair of members, said connection assembly including a first opening in one said member, a second opening in the other said member at least partially aligned with said first opening, said first opening being defined by two sections, said sections having centre lines offset from each other and wherein portions of each said section are aligned to define a generally cylindrical passage through said first member of a selected diameter, said second opening having a second transverse dimension, a shear pin extending through said first and second openings for interconnecting said first and second members, said shear pin having a diameter slightly less than said ~k1 6 selected diameter and extending through said defined passage in said first member and said opening in said second member.

The second opening suitably has a side wall portion against which said shear pin is a snug fit when said members are interconnected.

Most preferably the second opening comprises an opening with at least a portion of a transverse dimension greater than said selected diameter.

Suitably the sections of said first opening are generally oblong in cross section.

The one member preferably includes a further opening spaced from and aligned with the first opening and the second opening is disposed between said first and further openings when said members are interconnected.

o0 It is an object of the present invention to provide an inexpensive, reliable and easy to use tool assembly which is protected from damage should obstructions be encountered which stress the assembly a selected amount.

20 It is another object of the present invention to provide a tool assembly which efficiently transfers vibrations to the ground working point of the implement to o::0 minimise drag on the implement and maximise fracturing of o 0 0the soil being cultivated.

25 It is still another object of the present 0 invention to provide a tool assembly which can easily and reliably be reconnected to the tool bar after any failure I"1 0 *of a shear pin resulting from encountering an obstruction.

It is yet another object of the present invention to provide a tool assembly in which, after failure of a 2 shear pin, the assembly can be quickly and easily remounted to the tool bar by insertion of a new shear pin.

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\3 00* ePtl 0 4 er 0 0 o00 r~ro 0 4 a e 04044 0 4 a a 4 7 It is a further object of the present invention to provide a shear pin connection assembly for interconnecting a pair of members in a manner in which permits ready replacement and reinsertion of the shear pin in the event of failure.

Still other aspects, objects, and advantages of the present invention can be obtained by a study of the drawings, the specification, and the appended claims.

Brief Description of the Drawings Figure 1 is a side view of the tool assembly of the 10 preferred embodiment as mounted to a tool bar; Figure 2 is a side view similar to Fig. 1, but showing the assembly following failure of a shear pin; Figure 3 is a view of the clamping plate and shank assembly in a fully opened non-operative position; 15 Figure 4 is a side elevation of the clamping plate; Figure 5 is a cross-sectional view taken along line of Fig. 4, showing the openings through the prongs of the clamping plate; Figure 6A is a cross-sectional view taken along line 20 A-A of Fig. Figure 6B is a cross-sectional view taken along line B-B of Fig. 5; and Figure 6C is a cross-sectional view taken along line C-C of Fig. Description of the Preferred Embodiment An exemplary embodiment of a soil penetrating tool assembly 10 including the shear pin configuration of the present invention is shown generally in Figure 1 in a fully assembled configuration.

The tool assembly includes a shank member 12 constructed of a durable material, such as cast or forged metals, preferably steel. The shank member 12 consists of an elongate body 14, a soil penetrating tool 15 located at the lower end of the elongate body 14, and an upwardly and rearwardly facing plate 16 located on the upper end of the elongate body 14.

The elongate body 14 and the soil penetrating tool

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8 can be of any suitable configuration, including standard configurations presently widely used and well established in the industry. The leading edge of the soil penetrating tool has a pointed edge 17 to ease in the penetration of the soil.

The facing plate 16 is slightly longer than the shank member 12 and has an upright lug 18 extending beyond one end.

The facing plate 16 also includes a flange 20 rearward of the lug 18 and angled downwardly from the upwardly facing plate 16.

10 The facing plate 16 is directly mounted to a suitable tool bar or cross bar 22 of a cultivator as described further hereafter. Although the cross bar 22 may be of any cornfiguration which is not cylindrical in cross-section, typically cross bars have a generally square cross-section such as shown in Figures 1 and 2.

The lug 18 includes a through hole 24 which is generally oblong in cross-section and parallel to the cross bar 22 as shown in Figure 2. An ear 26 extends upward and rearward from the hole 24 of the lug 18. This ear 26 has an opening 28 20 through which a tool such as a crow bar or other like lever (not shown) can be inserted to assist in the assembly of the soil penetrating tool assembly An L-shaped clamping tlate 30 is provided with a flanged end 34 and a forked end 36 having two prongs 38 and each having oblong shaped holes or openings 42, 43 therethrough. As best shown in Figs. 5 and 6A-C, each of the prong openings include two sections 44, 45 which are each generally oblong in cross-section, and which are offset from S one another so that the overlapping portions of the sections S- 30 44, 45 define a generally cylindrical passage 46 therethrough with a selected diameter (see Figure 60). A transitional section 47 of the opening is also preferably included between the two opening sections 44, 45 of each prong 38, 40 so that there is no location at which the openings 42, 43 are actually as small as the defined cylindrical passage 46.

Two holes 48 located in the flanged end 34 of the i ii,. *1

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it ia~dL 7Lr clamping plate 30 are aligned with two holes 49 in the lower rear portion of the flange 20 of the shank member 12 when the soil penetrating tool assembly 10 is supported on the cross bar 22 with the facing plate 16 contacting the bottom and the front of the cross bar 22 and the clamping plate 30 contacting the top and back of the cross bar 22. Bolts 50 and nuts 51 are disposed in the aligned holes 48, 49 to secure the clamping plate flanged end 34 and the facing plate flange 20 together in a spaced apart relation when the cross bar 22 is enclosed between the clamping plate 30 and shank member facing plate 16 as shown in Figure 1.

When the assembly 10 is properly mounted to the cross bar 22, the clamping plate r'rong openings 42, 43 and the shank member lug through hole 24 are aligned with a shear pin 54 extending therethrough. The shear pin 54 is preferably substantially cylindrical with a diameter small enough to fit easily but snugly through the defined cylindrical passage 46 (see Figure 6C), and the oblong lug through hole 24 is located so that a side wall portion of the hole 24 which engages the shear pin 54 (as should be apparent) during mounting will, in combination with the bolts 50 and nuts 51, function to secure the clamp plate 30 and the facing plate together and against the cross bar 22. The lug through hole 24 preferably includes a part arcuate portion of substantially the same radius as the shear pin radius and which comprises the side wall portion with which the shear pin engages snugly in use. The remainder of the iug through hole 24 may be oblong as stated above or of any other shape such as to not only permit a clean shear of the shear pin but also allow the shear pin to be removed easily 30 from the hole 24. The hole 24 thus may diverge in transverse dimension fron the arcuate portion.

Such direct contact of the assembly 10 with the cross bar 22 not only restrains movement of the shank member 12 to maintain the desired orientation, but it also acts to directly pass vibrations in the cross bar 22 through to the shank member 12 for preferred operation in which the vibrations help to smoothly work the soil penetrating tool through the soil as 1 i i

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o Cr 000, previously discussed. That is, this rigid mounting minimizes any dampening ef-fect in the connection to assure that the vibrations generated in the tilling process remain at the shank of the tool in order to provide vibrations to assist in the tilling process. The presence of these vibrations improve the crumbling of the soil and also reduce the power necessary to move the soil penetrating tool through the soil.

Referring now to Figure 2, in the event that the soil penetrating tool assembly 10 hits an obstruction such as a rock, rather than damage the cross bar 22 or other components of the implement, the shear pin 54 will shear to free the shank ember lug 18 from the clamping plate 30. Due to the spacing of the clamping plate flanged end 34 from the facing plate flange 20, as well as the enlarged size of the holes 48, 49 15 relative to the bolts 50, the clamping plate 30 and facing plate flange 20 will pivot relative to one another as shown in Figure 2 (without damaging the bolts 50) sufficiently so that the shank member 12 may pivot about the cross bar 22 until it is clear of the obstruction. Further, the tool assembly will, even after failure of the shear pin 54, typically remain connected to the cross bar 22 such as shown in Figure 2.

Therefore, trailing components of the implement will not risk damage by running over a disconnected shank member 12 and, of course, an operator will not have to walk through the field hunting for the soil penetrating tool and/or for the clamping plate 20 in such itnstances.

Once an understanding of the above described invention is had, it should be recognized that while the shear pin 54 will be securely held in place during normal operation, if the 30 pin 54 is sheared the pieces which remain after failure will not be restrained (because each piece will not be in any two of the holes 24, 42, 43 and each of those holes are larger than the cross-sectional size of the pin 54). Therefore, the pieces of the pin 54 will not be wedged in as can occur with conventional structures, and thus remounting of the tool assembly can be easily accomplished without having to pry distorted remnants of the pin 54 from any of the holes 24, 42, 43.

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-ii ii ~ara7(t U-h 11 That is, after the remnants of the shear pin 54 are removed, the tool assembly 10 may be firmly reattached to the tool cross bar 22 by simply realigning the holes 24, 42, 43 (for example, by inserting a suitable tool in the ear opening 28 as leverage for pushing against the shoulder 56 on the clamping plate 30 [see Figure 11), and then new shear pin 54 may be inserted, typically by a simple hammer blow). this feature permits an individual operator to make the shear pin 54 replacement without assistance from another individual.

10 If necessary or to ease in mounting, the bolts 50 and nuts 51 can be loosened or tightened to ensure a secure mounting which will properly transmit vibrations as previously K::o discussed. However, it is tyoically not necessary to re-adjust o the position of the nuts 51 on the bolts 50 each time a failed shear pin is replaced.

Typically, frictional forces will be sufficient to maintain a shear pin 54 within the holes 24, 42, 43 when it *0St functions to hold the clamping plate 30 and shank assembly lug 18 together and the attaching bolts 50 are suitably tightened, S 20 and therefore no additional restraining means should be required. If desired as a security measure, however, any suitable such means could be used.

Further, it should be understood by those skilled in this art that the above configuration does not require any diameter reduction or other forms of necking at the shear points in the shear pin 54 as is required in some prior art to minimize distortion. Accordingly, shear pins 54 having a generally smaller cross-sectional area can be utilized with the present invention, and such simple shear pins 54 are both Dl .30 inexpensive and provide a more consistent and reliably determinable force required for shear failure.

In summary, soil penetrating tool assemblies embodying the present invention provide maximum reliability and ease of use at minimum cost.

Still other aspects, objects and advantages of the present invention can be obtained from a study of the specification, the drawings, and the appended claims.

Claims

1. A soil penetrating tool assembly for mounting to a tool bar of a soil penetrating implement compri-sing: a shank member having an elongate body, a soil penetrating tool located on a f irst end of said body, and a facing plate located on a second end of said body, said facing plate engaging one side of said tool bar when mounted to said tool bar, said facing plate having a first end and a second end, said f acing plate second end having a f acing plate opening with a f irst selected transverse dimension; a clamping plate engaging another side of the tool bar when mounted thereto, said clamping plate having a f irst end and a second end, said clamping plate second end having a clamping plate opening extending therethrough, said clamping plate opening having two sections offset from one another with different centre lines with portions of each of said section being aligned to def ine a generally cylindrical passage therethrough having a selected diameter; said openings in said f acing plate and clamping plate having axes extending substantially parallel to said tool bar when said 'Lacing and clamping plates are mounted to said tool bar; means for securing said facing plate first end to said clamping plate first end; and a substantially cylindrical shear pin having a diameter slightly less than the selected diameter and extending through the defined passage in the clamping plate opening and through the facing plate opening when said shank member is mounted to said tool bar.

2. The assembly of Claim 1 wherein said clamping plate first end and said facing plate first end include facing flanges each having a through hole and said securing means is a bolt extending through said through holes. -At The assembly of Claim I or Claim 2 wherein a 13 clearance between said facing plate first end and said clamping plate first end is maintained when said ends are secured together whereby upon failure of said shear pin said shank member and clamping plate may pivot about the bolt and clear of the tool bar to allow movement of the shank member about the tool bar.

4. The assembly of any one of Claims 1 to 3 wherein said shear pin is snugly fit against at least one side of the facing plate opening and at least one side of each section of the clamping plate openings when said shank member is mounted to said tool bar with the shear pin extending through said passage.

5. The assembly of any one of Claims 1 to 4 wherein said shank member is rigidly secured to said tool bar whereby vibrations in said bar are transmitted to said shank member.

6. The assembly of any one of Claims 1 to 5 wherein said sections of the clamping plate openings are generally oblong in cross-section.

7. A shear pin connection assembly for inter- connecting a pair of members, said connection assembly including a first opening in one said member, a second opening in the other said member at least partially aligned with said first opening, said first opening being defined by two sections, said sections having centre lines offset 30 from each other and wherein portions of each said section are aligned to define a generally cylindrical passage through said first member of a selected diameter, said second opening having a second transverse dimension, a shear pin extending through said first and second openings for interconnecting said first and second members, said shear pin having a diameter substantially the same as or slightly less than said selected diameter and extending through said defined passage in said first member and said e* :1 i! IL? 14 opening in said second member.

8. A connection assembly according to Claim 7 wherein said second opening has a side wall portion against which said shear pin is a snug fit when said members are interconnected by said shear pin.

9. A connection assembly according to Claim 7 or Claim 8 wherein said sections of said first opening are generally oblong in cross section. A connection assembly according to any one of Claims 7 to 9 wherein said one member includes a further opening spaced from and aligned with said first opening and wherein said second opening of said other member is I disposed between said first and further openings when said members are interconnected.

11. A connection assembly according to Claim wherein said further opening has a pair of sections, said sections having centre lines offset from each other, portions of each said sections being aligned to define a further cylindrical passage of said selected diameter and aligned with the first said cylindrical passage.

12. A shear pin connection assembly substantially as hereinbefore described with reference to the accompanying drawings.

13. A soil penetrating tool assembly substantially as i hereinbefore described with reference to the accompanying drawings DATED this eighteenth day of October 1994 i ALLAN JAMS YEOMANS BY MY PATENT ATTORNEY JOHN R.G. GARDNER Abstract I' A soil penetrating tool assembly (10) for mounting to S' a tool bar (22) of a soil penetrating implement including a shank member (12) and a facing plate (16) which engages one side of the tool bar (22) and which has an opening A clamping plate (30) engages the other side of the tool bar (22) and has a forked end (36) which has two prongs (38) each having openings (42) including two sections, generally oblong in cross-section, offset from one another with different centrelines. The opening sections in each of the clamping plate prongs (36) and the facing plate opening (24) define a generally cylindrical passage therethrough with a selected diameter when the shank member (12) is mounted to the tool bar (22) and a shear pin (54) extends through that defined passage. a2'I V^ |j