Claims:We claim:

1. A structurally safe adjustable lower link assembly for tractors, wherein the lower link comprises a forged eye made with pads projected from the top and bottom faces of the lower link and disposed substantially adjacent the forged eye end thereof.

2. Adjustable lower link assembly as claimed in claim 1, wherein at least a pair of projected pads is configured on the forged eye end of the lower link.

3. Adjustable lower link assembly as claimed in claim 2, wherein the projected pads are configured mutually parallel and running transverse to the length of the lower link.

4. Adjustable lower link assembly as claimed in claim 3, wherein each projected pad of each pairs of projected pads is substantially equidistance from the pivot pin of the lower link forged eye.

5. A structurally safe adjustable lower link assembly for tractors, wherein the lower link comprises a forged eye made with at least a pair of pads projecting from the top and bottom faces of the lower link and disposed adjacent the forged eye end thereof.

6. Adjustable lower link assembly as claimed in claim 5, wherein the pair of the projected pads are configured parallel to each other and extending transverse to the length of the lower link.

7. Adjustable lower link assembly as claimed in claim 6, wherein the distance of each projected pad of the respective pair is optimized from the pivot pin center of the lower link forged eye for avoiding structural and weld failures therein.

8. Adjustable lower link assembly as claimed in claim 6, wherein the distance of projected pads of the respective pair is optimized from the pivot pin center of the lower link forged eye for reducing the stress developed therein due to impact loading on the U-bracket and top plate of the lower link.
9. A structurally safe adjustable lower link assembly for tractors, wherein the assembly comprises:

• a lower link configured with a forged eye;
• a U-bracket configured with a pivoting slot for adjusting the length of the lower link;
• a top plate welded on top of the U-bracket; and
• a pivot pin for adjusting the pivoting location of the pivot pin in the pivoting slot in the U-bracket;

wherein a respective pair of pads is configured projecting from the top and bottom faces of the lower link adjacent the forged eye end thereof and extending transversely therefrom and disposed parallel to each other.

10. Adjustable lower link assembly as claimed in claim 1, wherein the distances of the projected pads are optimized, preferably made equidistance from the pivot pin center of the lower link forged eye.

Dated: this 31st day of July 2017. SANJAY KESHARWANI
APPLICANT’S PATENT AGENT , Description:FIELD OF INVENTION

The present invention relates to the three-point linkage (3PL) or hitch system of tractors. In particular, the present invention relates to adjustable lower link of 3PL system of tractors. More particularly, the present invention relates to a forged eye configured with projected pads for adjustable lower link of 3PL system of tractors.

BACKGROUND OF THE INVENTION

In tractor operations, three-point linkage (3PL) or hitch system plays a vital role in supporting external implements. It acts as connecting member between the external implement and the tractor main frame. This 3PL assembly is capable of withstanding bending moments encountered while operating the tractor and using implement like rotavator etc. 3PL assembly (Figure 1a) mainly consists of parts: Top plate 02, U-bracket 04, Forged eye 06, Locking bracket 08, Lift rod 22, Lift arm 24, Rocker shaft 26, Check chain 28, Lower link 30, VTU housing 32, and Pin 34 (Figure 1b). It is used to attach various implements to the tractor, for fixing the orientation of the implement with respect to the tractor and with respect to the arm position of the linkage. Since tractor carries partial or full weight of the implement, the 3PL system transfers the weight and resistance of the implement to the drive wheels of the tractor. The 3PL system makes more traction available to the tractor than the tractors without a 3PL system, however for the same power and weight and therefore, with the same fuel consumption.

The three-point linkage system is operated by the hydraulic system of the tractor and includes the points for attachment, lifting arms, and stabilizers. The 3PL is made of three movable arms, i.e. two lower arms and a lifting arm, which are generally controlled by the tractor’s own hydraulic system for lifting, lowering, and tilting of these arms and the upper central arm or the top link. This hydraulic system is controlled by the tractor operator by means of different available settings. Each arm has an arrangement for connecting any desired implement to the three-point linkage. For attaching an implement, a plurality of holes is provided on each link, through which, the posts of the implement are secured by inserting a respective pin at the ends of these posts. Normally, a draft control mechanism is also provided in the three-point linkage, so that the draft or the amount of force taken for pulling the implement can be sensed on the lower arms and these can be slightly raised or lowered automatically with increased or reduced draft by the tractor’s hydraulic system.

PRIOR ART

At present, the adjustable lower link of the three-point linkage assembly is generally made of forged eye configured with a gap between the U-bracket and the top plate.

DISADVANTAGES WITH THE PRIOR ART

The following are the disadvantages with the conventional adjustable lower link of the 3-point linkage (3PL) assembly discussed above:

• Structural and weld failures of the lower link.

• Impact loads on U-bracket and top plate of the adjustable lower link.

• Higher stresses are developed between the top plate edge and the U-bracket.

• Difficult to manufacture and assemble.

• Additional strengthening required.

• Gap between U-bracket and top plate causes structural failure of lower link due to edge loading.

• Gap between U-bracket and top plate causes structural failure of lower link due to impact loading therebetween.

OBJECTS OF THE INVENTION

Some of the objects of the present invention - satisfied by at least one embodiment of the present invention - are as follows:

An object of the present invention is to provide an improved adjustable lower link of the 3PL assembly, which eliminates structural and weld failures of lower link thereof.

Another object of the present invention is to provide an improved adjustable lower link of the 3PL assembly, which eliminates impact loads on adjustable lower link and top plate thereof.

Still another object of the present invention is to provide an improved adjustable lower link of the 3PL assembly, which reduces stress developed therein.

Yet another object of the present invention is to provide an improved adjustable lower link of the 3PL assembly, which is simple to manufacture and facilitates assembly thereof.

A still further object of the present invention is to provide an improved adjustable lower link of the 3PL assembly, which requires no additional strengthening thereof.

A yet further object of the present invention is to provide an improved adjustable lower link of the 3PL assembly, which does not require any gap between the U-bracket and top plate.

An additional object of the present invention is to provide an improved adjustable lower link of the 3PL assembly, which avoids edge loading of the top plate.

These and other objects and advantages of the present invention will become more apparent from the following description, when read with the accompanying figures of drawing, which are however not intended to limit the scope of the present invention in any way.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided a structurally safe adjustable lower link assembly for tractors, the lower link comprising a forged eye made with pads projected from the top and bottom faces of the lower link and disposed substantially adjacent the forged eye end thereof.

Typically, at least one pair of projected pads is configured on the forged eye end of the lower link.

Typically, the projected pads are configured mutually parallel and running transverse to the length of the lower link.

Typically, each projected pad of each pairs of projected pads is substantially equidistance from the pivot pin of the lower link forged eye.

Typically, the lower link comprises a forged eye made with at least a pair of pads projecting from the top and bottom faces of the lower link and disposed adjacent the forged eye end thereof.

Typically, the pair of the projected pads are configured parallel to each other and extending transverse to the length of the lower link.

Typically, the distance of each projected pad of the respective pair is optimized from the pivot pin center of the lower link forged eye for avoiding structural and weld failures therein.

Typically, the distance of projected pads of the respective pair is optimized from the pivot pin center of the lower link forged eye for reducing the stress developed therein due to impact loading on the U-bracket and top plate of the lower link.

According to an embodiment of the present invention, there is provided a structurally safe adjustable lower link assembly for tractors, the assembly comprising:

• a lower link configured with a forged eye;

• a U-bracket configured with a pivoting slot for adjusting the length of the lower link;
• a top plate welded on top of the U-bracket; and

• a pivot pin for adjusting the pivoting location of the pivot pin in the pivoting slot in the U-bracket;

wherein a respective pair of pads is configured projecting from the top and bottom faces of the lower link adjacent the forged eye end thereof and extending transversely therefrom and disposed parallel to each other.

Typically, the distances of the projected pads are optimized, preferably made equidistance from the pivot pin center of the lower link forged eye.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The present invention will be briefly described with reference to the accompanying drawings, wherein:

Figure 1a shows a conventional three-point linkage assembly including an adjustable lower link assembly with a forged eye.

Figure 1b shows another enlarged view of the conventional adjustable lower link assembly of Figure 1a.

Figure 1c shows another view of the conventional adjustable lower link assembly of Fig.1b marked with section line X-X and the locations and of the gap to be provided between the top plate and the U-bracket.

Figure 1d shows a further enlarged view of the assembly of the top plate and U-bracket cut along section line X-X of Fig. 1c.

Figure 1e shows an actual view of the crack C developed in of the lower link due to the forged eye hitting the top plate at location in the gap region.

Figure 2 shows a conventional adjustable telescopic forged eye of the adjustable telescopic lower link assembly of Figure 1a.

Figure 3a shows a cross-sectional view of an improved adjustable telescopic forged eye 106 of the adjustable telescopic lower link assembly configured in accordance with the present invention.

Figure 3b shows a perspective view of the adjustable telescopic forged eye of Fig. 3a showing projected pads configured both on top and bottom faces thereof.

Figure 4a shows a conventional adjustable lower link assembly having its top plate joined to the U-bracket and pivoted at the pivoting location by means of a pin.

Figure 4b shows the conventional forged eye 06 of Figure 4a indicating the locations SL1 and SL2 of maximum stress locations development therein.

Figure 4c shows the top plate of conventional Fig. 4a indicating the edge of maximum stress development locations.

Figure 4d shows the conventional U-bracket of Figure 4a indicating the maximum stress development locations.

Figure 4e shows an enlarged view of the stress plot of Fig. 4d indicating the maximum stress locations.

Figure 5a shows an adjustable lower link assembly configured in accordance with the present invention.

Figure 5b shows the forged eye of Fig. 5a indicating the projected pads configured at locations with maximum stress development therein.

Figure 5c shows the top plate of Fig. 5a indicating the edge of maximum stress development locations.

Figure 5d shows an enlarged view of the stress plot of the maximum stress development locations and the maximum stresses at top edges and pivot pin location.
Figure 6 shows a set-up for fatigue test for vertical load case conducted on the conventional adjustable lower link assembly and the location 60 of the crack developed therein (Fig.1e).

Figure 7a shows an existing forged eye for the adjustable lower link assembly, which is quite complicated in design.

Figure 7b shows another existing forged eye for the adjustable lower link assembly, which is also quite complicated in design.

Figure 7c shows still another existing forged eye for the adjustable lower link assembly, which is quite complicated in design as well.

DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS

In the following, the adjustable telescopic lower link assembly configured in accordance with the present invention will be described in more details with reference to the accompanying drawings without limiting the scope and ambit of the present invention in any way.

Figure 1a shows a conventional three (3) point linkage assembly including an adjustable lower link assembly 10 with a forged eye. The assembly further consists of lift rod 22, lift arm 24, rocker shaft 26, check chain assembly 28, lower link 30, VTU housing 32, and pin 34 respectively.

Figure 1b shows another enlarged view of the conventional adjustable lower link assembly 10 of Fig.1a and having top plate 02, U-bracket 04, forged eye 06, locking bracket 08.

Figure 1c shows another view of the conventional adjustable lower link assembly 10 of Figure 1b marked with section line X-X and the locations L1 and L2 of the gap G1 (Fig. 1d) to be provided between the top plate 02 and the U-bracket 04 of the adjustable telescopic lower link assembly 10, which facilitates assembly and adjustment of the length.

Figure 1d shows a further enlarged view of the assembly of the top plate 02 and U-bracket 04 cut along section line X-X of Fig. 1c. Here, the gap G1 is provided between the top plate 02 and the U-bracket 04 of the adjustable telescopic lower link assembly 10, which facilitates assembly and adjustment of the length. However, this gap G1 causes the forged eye 06 to hit the top plate at location L1, which leads to failure of the lower link 30.

Figure 1e shows an actual view of the crack C developed in of the lower link 30 due to the forged eye 06 hitting the top plate at location L1 in the region 60 of gap G1.

Figure 2 shows a conventional adjustable telescopic forged eye 06 of the adjustable telescopic lower link assembly 10 of Figure 1a. Here, pivot location 36 of the pin 34 is shown for adjusting the overall length of the lower link 30 (not shown, see Fig. 1a).

Figure 3a shows a cross-sectional view of an improved adjustable telescopic forged eye 106 of the adjustable telescopic lower link assembly configured in accordance with the present invention. Here, the improvement consists of a plurality of projected pads 138, preferably 4 projected pads, more preferably two projected pads spaced apart and configured on top and bottom faces of the forged eye 106, which are configured away from the edge of the gap G3 between the top plate 102 and U-bracket joint 104 and from the gap G4 between the lower face of the forged eye 106 and the U-bracket 104. This improved configuration of the forged eye 106 helps in shifting the location of the forged eye 106 end hitting the top plate 102, thereby eliminating the failure of the lower link, as was prevalent in the conventional adjustable lower link assembly 10 of Figs. 1a - 1d.

Figure 3b shows a perspective view of the improved adjustable telescopic forged eye 106 of Fig. 3a showing two mutually spaced apart projected pads 138 configured both on top and bottom faces of the forged eye 106. These are configured on either side of the pivot location 136 of the pivot pin 134 (not shown here). This configuration eliminates the impact loads on the adjustable lower link U-bracket 102 and top plate 104 thereof. It also simplifies manufacture and assembly of the adjustable lower link assembly. This improved configuration also eliminates structural and weld failures in the conventional adjustable lower link assembly.

Figure 4a shows a conventional adjustable lower link assembly having its top plate 02 joined to the U-bracket 04 and pivoted at the pivoting location 32 by pivot pin 34.

Figure 4b shows the conventional forged eye 06 of Figure 4a indicating the locations SL1 and SL2 of maximum stress locations development therein. From the stress plots drawn for this conventional forged eye 06, the maximum stresses observed at locations SL1 and SL2 were about 2674 MPa and 1948 MPa respectively and were considerably high.

Figure 4c shows the top plate 02 of conventional Figure 4a indicating the edge SL3 of maximum stress locations development therein. The maximum stresses observed at this location SL3 were about 10088 MPa, which was considered extremely high.

Figure 4d shows the conventional U-bracket 04 of Figure 4a indicating the region 50 of maximum stress locations development therein.

Figure 4e shows an enlarged view of the stress plot of Fig. 4d indicating the region 50 of maximum stress locations development and the maximum stresses observed at pivot pin location SL4 and top edge SL5, which were about 1492 MPa and 3505 MPa respectively.

Figure 5a shows an adjustable lower link assembly 110 configured in accordance with the present invention and having its top plate 102 joined to the U-bracket 104 and forged eye 106 pivoted at the pivoting location 132 by means of a pivot pin 134. The forged eye 106 is provided with a plurality of projected pads 138 configured on the upper and lower faces thereof (see Fig. 5b) according to the present invention. The optimal distance of the projected pads 138 from the center of the pin 134 drastically reduces the stress and thereby eliminates structural and weld failures in the region of top plate and U-bracket joint.

Figure 5b shows the forged eye 106 of Figure 5a indicating the projected pads 138 configured at locations SL11 and SL12 with maximum stress development therein. The maximum stresses observed at locations SL11 and SL12 were about 1243 MPa and 1388 MPa respectively, which are substantially lower with respect to conventional forged eye 06.

Figure 5c shows the top plate 102 of Figure 5a indicating the edge SL13 of maximum stress locations development therein. The maximum stresses observed at this location SL13 were about 1163 MPa, which is substantially reduced with respect to the top plate 02 of the conventional adjustable lower link assembly 10.

Figure 5d shows an enlarged view of the stress plot of the region 50 of maximum stress locations development and the maximum stresses observed at top edges SL14-SL15 and pivot pin location SL16 are observed to be about 405-602 MPa and 645 MPa respectively.

Figure 6 shows a set-up for fatigue test for vertical load case conducted on the conventional adjustable lower link assembly and the location 60 of the crack developed therein (see Figure 1e). The crack is initiated in the weld area and then penetrates to the top plate 04.

Figure 7a shows an existing forged eye for the adjustable lower link assembly, which is quite complicated in design.

Figure 7b shows another existing forged eye for the adjustable lower link assembly, which is also quite complicated in design.

Figure 7c shows still another existing forged eye for the adjustable lower link assembly, which is quite complicated in design as well.

TECHNICAL ADVANTAGES AND ECONOMIC SIGNIFICANCE

The adjustable lower link assembly with pads projected on the lower link configured in accordance with the present invention has the following technical and economic advantages:

• Eliminates structural and weld failures of the lower link.

• Eliminates impact loading on U-bracket and top plate of adjustable lower link.

• Reduces stresses developed between the top plate edge and U-bracket.

• Ease of manufacture and assembly.

• Additional strengthening not required.

• Avoids edge loading of the lower link.

• Eliminates structural failure of lower link due to impact loading.

The exemplary embodiments described in this specification are intended merely to provide an understanding of various manners in which this embodiment may be used and to further enable the skilled person in the relevant art to practice this invention. The description provided herein is purely by way of example and illustration.

Although, the embodiments presented in this disclosure have been described in terms of its preferred embodiments, the skilled person in the art would readily recognize that these embodiments can be applied with modifications possible within the spirit and scope of the present invention as described in this specification by making innumerable changes, variations, modifications, alterations and/or integrations in terms of materials and method used to configure, manufacture and assemble various constituents, components, subassemblies and assemblies, in terms of their size, shapes, orientations and interrelationships without departing from the scope and spirit of the present invention.

While considerable emphasis has been placed on the specific features of the preferred embodiment described here, it will be appreciated that many additional features can be added and that many changes can be made in the preferred embodiments without departing from the principles of the invention. These and other changes in the preferred embodiment of the invention will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

Many of the fastening, connection, processes and other means and components utilized in this invention are widely known and used in the field of the invention described, and their exact nature or type is not necessary for an understanding and use of the invention by a person skilled in the art and they will not therefore be discussed in significant detail.

The numerical values given of various physical parameters, dimensions and quantities are only approximate values and it is envisaged that the values higher or lower than the numerical value assigned to the physical parameters, dimensions and quantities fall within the scope of the disclosure unless there is a statement in the specification to the contrary.

Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, shall be understood to implies including a described element, integer or method step, or group of elements, integers or method steps, however, does not imply excluding any other element, integer or step, or group of elements, integers or method steps.

The use of the expression “a”, “at least” or “at least one” shall imply using one or more elements or ingredients or quantities, as used in the embodiment of the disclosure in order to achieve one or more of the intended objects or results of the present invention.

Also, any reference herein to the terms ‘left’ or ‘right, ‘up’ or ‘down, or ‘top’ or ‘bottom’ are used as a matter of mere convenience, and are determined by standing at the rear of the machine facing in its normal direction of travel. Furthermore, the various components shown or described herein for any specific application of this invention can be widely known or used in the art by persons skilled in the art and each will likewise not therefore be discussed in significant detail. When referring to the figures, like parts are numbered the same in all of the figures.