FIELD OF INVENTION
The present invention relates to a hydraulic assembly and lifting mechanism for tractors. In particular, the present invention relates to a hydraulic connecting rod for the hydraulic assembly. More particularly, the present invention relates to tractor’s hydraulic connecting rod having a cross-ribbed configuration.
BACKGROUND OF THE INVENTION
The hydraulic connecting rod is a part of the hydraulic assembly and the hydraulic lifting mechanism of a tractor. The hydraulic connecting rod basically functions as a short column, which is subjected to the operating hydraulic pressure of the hydraulic lifting mechanism. Thus, stresses are induced in the connecting rod due to the hydraulic pressure as well as buckling load operating thereon. To withstand both the hydraulic pressure and the buckling load, the hydraulic connecting rod configuration needs validation through CAE analysis.
DISADVANTAGES WITH THE PRIOR ART
The following are the disadvantages associated with the existing hydraulic connecting rods of tractors.
• Higher weight and therefore higher cost of the hydraulic connecting rod.
• Even by changing the circular-section of the connecting rod to I-section during the initial stage, the connecting rod was configured according to the support and durability requirements.
• However, this I-section configuration does not meet the CAE acceptance criteria due to a lower buckling factor.
• From simulation, it was confirmed that the buckling of I-section connecting rod is uniform in all the directions.

Therefore, there is a need to re-design the hydraulic connecting rod for tractor hydraulic lifting mechanism to improve the buckling factor.
DESCRIPTION OF THE INVENTION
In most of the hydraulic connecting rod having a circular cross-section, the circular connecting rod has a uniform strength in all directions and meets the buckling factor. However, this leads to an increase in the weight and thus the cost of manufacture is substantially high. In order to avoid this issue, the connecting rod needs to be configured so as to withstand the buckling load as well as the hydraulic pressure acting thereon.
In accordance with the present invention, a hydraulic connecting rod having a cross-section with four (4) cross-ribs is configured to have a uniform strength in all the directions. Generally, the ribs impart a better strength and durability to the component, e.g. the hydraulic connecting rod here.
The connecting rod with four ribs, having 5 mm fillet radius and minimum rib thickness is 5 mm. The rib height is 19 mm and the rib top length is 10 mm. The buckling factor meets different variables. The main possible variables are as under:
The main design variables possible are as under:
1. Fillet radius,
2. Rib height,
3. No of ribs,
4. Rib top length, and
5. Rib thickness
The hydraulic connecting rod having a cross-section with four cross-ribs configured in accordance with the present invention has the following advantages:
1. Uniform strength in all direction.
2. Connecting rod having a cross-section with 4 cross-ribs.

3. High buckling strength.
4. Ease of manufacturing.
The cost advantages of the hydraulic connecting rod having a cross-section with four cross-ribs configured in accordance with the present invention are given below:
• Light weight and maintains the component strength.
• A weight saving of approx. 25-30% and therefore a proportionate cost saving.
• The component meets the performance as per the CAE acceptance criteria in terms of the stress and the buckling factor.
• Uniform strength in all the direction.
• Optimum configuration of the hydraulic connecting rod with 4 ribs.
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 improve hydraulic connecting rod for hydraulic lifting mechanism of the tractors.
Another object of the present invention is to provide a hydraulic connecting rod for hydraulic lifting mechanism having a higher buckling strength.
Still another object of the present invention is to provide a hydraulic connecting rod for hydraulic lifting mechanism which better withstands the hydraulic pressure.
Yet another object of the present invention is to provide a hydraulic connecting rod for hydraulic lifting mechanism having a substantially reduced weight.

A further object of the present invention is to provide a hydraulic connecting rod for hydraulic lifting mechanism having a uniform strength in all directions.
A still further object of the present invention is to provide a hydraulic connecting rod for hydraulic lifting mechanism having variable configuration as per the requirements.
A yet further object of the present invention is to provide a hydraulic connecting rod for hydraulic lifting mechanism, which is easy to manufacture.
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 ribbed hydraulic connecting rod for a tractor hydraulic assembly, wherein the ribs are configured cross-ribbed with substantial weight reduction thereof and for withstanding the buckling load as well as hydraulic pressure acting thereon.
Typically, the weight of the connecting rod is between 25 to 35%, preferably 30 to 33% less than the connecting rod of circular cross-section to meet the buckling factor criteria.
Typically, the ribs comprise two profiled ribs of equal height and thickness and are mutually crossing at right angle and configured with first fillet radii therebetween and either end of the ribs connected to a respective lobe of the connecting rod with a second fillet radii.
Typically, each profiled rib comprises a triangular profile with a peak making a predefined acute angle with the axis of the connecting rod.

Typically, each profiled rib comprises a top truncated flat portion of a predetermined length.
Typically, the ribs comprise cross-ribbed ribs in a star configuration.
Typically, the ribs comprise a circular mid-rib of predetermined thickness and diameter at the centre of the connecting rod.
Typically, the ribs comprise a circular starting rib of predetermined thickness and diameter adjacent one of the lobes of the connecting rod.
Typically, each profiled rib is connected to a respective lobe of the connecting rod at either end thereof with a third fillet radius.
Typically, the buckling factor of the connecting rod is between 3 to 7, preferably about 4.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The present invention will be briefly described with reference to the accompanying drawings, wherein:
Figure 1 shows a perspective view of the hydraulic assembly of a hydraulic lifting mechanism of the tractor.
Figure 2 shows an enlarged view of the upper portion of the hydraulic assembly of a hydraulic lifting mechanism of the tractor depicted in Fig.1.
Figure 3 shows a cross-sectional view of the upper portion depicted in Fig.2.
Figure 4 shows perspective view of the hydraulic assembly depicted in Fig.3.
Figure 5a shows the conventional hydraulic connecting rod having a circular cross-section.

Figure 5b shows a cut sectional view of the conventional hydraulic connecting rod of Fig. 5a.
Figure 6a shows the hydraulic connecting rod having an I-section cross-section.
Figure 6b shows a sectional view of the hydraulic connecting rod of Fig. 6a.
Figure 7a shows a perspective view of the hydraulic connecting rod generally having a ribbed configuration, which is marked with a section-line X-X across the rib-top center thereof.
Figure 7b shows the hydraulic connecting rod of Fig.7a, particularly having a 3-rib cross-section and cut along section-line X-X.
Figure 7c shows a perspective partial isometric view of the hydraulic connecting rod of Fig.7c having a 3-rib cross-section cut along section-line X-X at the rib-top center thereof.
Figure 7d shows the hydraulic connecting rod of Fig.7b having a 4-rib cross-section and sectioned along the section-line X-X to be described subsequently as the first embodiment of the present invention.
Figure 7e shows the hydraulic connecting rod of Fig.7b having a 5-rib cross-section and sectioned along the section-line X-X.
Figure 7f shows a perspective partial isometric view of the hydraulic connecting rod of Fig.7f having a 5-rib cross-section cut along section-line X-X at the rib-top center thereof.
Figure 8a shows a side view of the hydraulic connecting rod generally having an improved ribbed cross-section and depicting various significant dimensions thereof.

Figure 8b shows a side view of the second embodiment of the hydraulic connecting rod having a 4-rib cross-section configured in accordance with the present invention and depicting various significant dimensions thereof.
Figure 8c shows a perspective view of the hydraulic connecting rod of Fig.8b marked with a section-line X1-X1 across the rib-top center thereof.
Figure 8d shows a sectional view of the hydraulic connecting rod of Fig.8b cut along the section-line X1-X1. The ribs Rb having fillet radii Rf1 and rib thickness Rt1 are marked therein.
Figure 8e shows a partial perspective isometric view of the hydraulic connecting rod of Fig.8b cut along the section-line X1-X1.
Figure 9a shows side view of the first embodiment of connecting rod of Fig.8a.
Figure 9b shows side view of the second embodiment of connecting rod of Fig.8b.
Figure 9c shows a perspective view of the hydraulic assembly with the hydraulic connecting rod having 4-rib cross-section configured in accordance with a third embodiment of the present invention.
Figure 9d is side view of a third embodiment of the connecting rod of Fig.9c.
Figure 10a shows a perspective view of the third embodiment (Fig. 9c) of the hydraulic connecting rod having a star cross-section configured according to present invention.
Figure 10b shows side view of the hydraulic connecting rod of Figure 10a.
Figure 11a shows a perspective view of the hydraulic connecting rod with 4-rib cross-section (Figs. 8b, 9b) configured with a mid-rib made in accordance with the present invention.

Figure 11b shows a perspective view of the hydraulic connecting rod with 4-rib cross-section (Figs.8b,9b) configured with a start-rib made in accordance with the present invention.
Figure 11c shows a perspective view of the hydraulic connecting rod with a 4-rib cross-section (Figs.8b,9b) configured with a fillet made in accordance with the present invention.
Figure 12 is a graphical representation of the relationship between the buckling factor and rib-top length for a hydraulic connecting rod having 4-rib cross-section configured in accordance with the present invention for different rib-heights therein.
DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS
In the following, the hydraulic connecting rod with a generally ribbed cross-section 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 1 shows a perspective view of the hydraulic assembly of a hydraulic lifting mechanism of the tractor. It includes a Position Control and Draft Control (PC-DC) lever assembly 02, rocker arm 04, rocker shaft 06, bell cranks 08, hydraulic connecting rod 10, vary-touch unit (VTU) housing 12, Lift arms 14, top link 16, lift rods 18 (LHS rod 18 is fixed type and the RHS rod 18 is adjustable type), check chain mounting bracket 20, check chain 22, lower link mounting bracket 24 and lower links 26, 28 respectively.
Figure 2 shows an enlarged perspective view of the upper portion of the hydraulic assembly of a hydraulic lifting mechanism of the tractor depicted in Figure 1 and depicting the hydraulic connecting rod 10 therein. It includes VTU housing 12 at the front end thereof; connecting rod 10 on LHS thereof; rocker shaft 06 with the rocker arm 04 connecting a lifting arm 14 at either side of the rear end thereof.

Figure 3 shows a cross-sectional view of the upper portion depicted in Figure 2 and indicating the dimensions significant for operating the hydraulic lifting mechanism. These dimensions include the perpendicular distance D between the connecting rod 10 and the center of the rocker arms 04, distance C1 between the center CLA of the lifting arm 18 and the center CRA of the rocker arm 04, distance C2 between the center CRA of the rocker arm 04 and the axis of the connecting rod 10, an angle α between the axis of the connecting rod 10 and the axis of the hydraulic cylinder, and an angle β between the axis of the connecting rod 10 and the line connecting the rear center of the connecting rod 10 to the center CRA of rocker arm 04.
Figure 4 shows a perspective view of the hydraulic assembly of Fig. 3 and indicating the rocker arm 04 carried on the rocker shaft 06 at the center thereof and a lift arm 14 connected at either end thereof and the hydraulic connecting rod 10 connected at the center of the rocker shaft 06.
Figure 5a shows the conventional hydraulic connecting rod 10 having a circular cross-section.
Figure 5b shows a cut sectional view of the hydraulic connecting rod 10 of Fig. 5a.
Figure 6a shows the hydraulic connecting rod 10 having an I-section cross-section on either side thereof connected at the center by a substantially rectangular cross-section 11.
Figure 6b shows a sectional view of the hydraulic connecting rod of Fig. 6a cut at the center thereof and showing one of the I-sections and central rectangular cross-section 11 thereof.
Figure 7a shows a perspective view of the hydraulic connecting rod generally having a ribbed configuration, which is marked with a section-line X-X across the rib-top center thereof.

Figure 7b shows the hydraulic connecting rod of Fig. 7a, particularly configured with a 3-rib cross-section and cut along section-line X-X with fillet radius Rf marked therein.
Figure 7c shows a perspective partial isometric view of the hydraulic connecting rod of Fig.7a having a 3-rib cross-section cut along section-line X-X at the rib-top center thereof.
Figure 7d shows the hydraulic connecting rod 100 configured with a 4-rib cross-section to meet the buckling factor criteria and sectioned along the section-line X-X as the first embodiment of the present invention.
Figure 7e shows the hydraulic connecting rod of Fig. 7a having a 5-rib cross-section and sectioned along the section-line X-X.
Figure 7f shows a perspective partial isometric view of the hydraulic connecting rod of Fig. 7e having a 5-rib cross-section cut along section-line X-X at the rib-top center thereof.
Figure 8a shows a side view of the hydraulic connecting rod generally having an improved 4-ribbed cross-section (Fig. 7d) and depicting various significant dimensions thereof. It includes fillet radius r3 of the ribs Rb with height H1 and thickness Rt, straight rib top length L1, connecting rod lobe radii R2 and its minimum radii r2 at ribs joint respectively.
Figure 8b shows a side view of the second embodiment of the hydraulic connecting rod 200 having a 4-rib cross-section configured in accordance with the present invention and depicting various significant dimensions thereof. It includes four ribs of central height H and thickness Rt, narrow straight rib-top length TL, connecting rod lobe radii R1 and the minimum radii r1 thereof at its joint with the ribs respectively. The tapered rib edges make an angle ϴ at the rib joints with the connecting rod lobe on either side thereof.
Figure 8c shows a perspective view of the hydraulic connecting rod of Fig.8a marked with a section-line X1-X1 across the rib-top center thereof.

Figure 8d shows a sectional view of the hydraulic connecting rod of Fig.8c cut along the section-line X1-X1. The ribs Rb having fillet radii Rf1 and rib thickness Rt1 are marked therein.
Figure 8e shows a partial perspective view of the hydraulic connecting rod of Fig. 8d cut along the section-line X1-X1.
Figure 9a shows side view of the first embodiment of connecting rod 100 of Fig. 8a configured with a 4-rib cross-section to meet the buckling factor criteria.
Figure 9b shows side view of second embodiment of connecting rod 200 of Fig. 8b configured with a 4-rib cross-section to meet the buckling factor criteria.
Figure 9c shows a perspective view of the hydraulic assembly with the third embodiment of the hydraulic connecting rod 300 having 4-rib cross-section configured in accordance with the present invention.
Figure 9d is side view of a third embodiment of the connecting rod 300 of Fig. 9c configured with a 4-rib cross-section to meet the buckling factor criteria.
Figure 10a shows a perspective view of the third embodiment (Fig. 9c) of the hydraulic connecting rod 300 having a star cross-section configured according to present invention.
Figure 10b shows side view of the hydraulic connecting rod of Fig. 9c.
Figure 11a shows a perspective view of the first embodiment of the hydraulic connecting rod with 4-rib cross-section 100 (Figs. 8b, 9b) configured with a mid-rib 110 made in accordance with the present invention.

Figure 11b shows a perspective view of the first embodiment of the hydraulic connecting rod with 4-rib cross-section (Figs. 8b, 9b) 100 configured with a start-rib 120 made in accordance with the present invention.
Figure 11c shows a perspective view of the hydraulic connecting rod with a 4-rib cross-section (Figs. 8b, 9b) 100 configured with a fillet 130 made in accordance with the present invention.
Figure 12 is a graphical representation of the relationship between the buckling factor and rib-top length for a hydraulic connecting rod having 4-rib cross-section configured in accordance with the present invention and depicted for different rib-heights therein. The buckling factors for different rib-top lengths, for example at 10, 30, 50 and 80 mm rib top-lengths are depicted for the connecting rods having rib-heights of 15, 17, 19 and 22.25 mm respectively.
TECHNICAL ADVANTAGES AND ECONOMIC SIGNIFICANCE
The hydraulic connecting rod with a generally ribbed cross-section configured in accordance with the present invention has the following technical and economic advantages:
• Higher buckling strength.
• Withstands the hydraulic pressure better.
• Substantially reduced weight.
• Uniform strength in all the directions.
• Offers variable configuration as per the requirements by changing the rib fillet radius, height, number, top length and thickness.
• Light weight and thus, maintains the component strength.
• Weight saving of about 25-35%.
• Substantial cost saving due to less weight thereof.

• Components meet the stress requirements specified under CAE acceptance criteria.
• Components meet the buckling factor requirements specified under CAE acceptance criteria.
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.

1. A ribbed hydraulic connecting rod for a tractor hydraulic assembly, wherein the ribs are configured cross-ribbed with substantial weight reduction thereof and for withstanding the buckling load as well as hydraulic pressure acting thereon.
2. Connecting rod as claimed in claim 1, wherein the weight of the connecting rod is between 25 to 35%, preferably 30 to 33% less than the connecting rod of circular cross-section to meet the buckling factor criteria.
3. Connecting rod as claimed in claim 1, wherein the ribs comprise two profiled ribs of equal height and thickness and are mutually crossing at right angle and configured with first fillet radii therebetween and either end of the ribs connected to a respective lobe of the connecting rod with a second fillet radii.
4. Connecting rod as claimed in claim 1, wherein each profiled rib comprises a triangular profile with a peak making a predefined acute angle with the axis of the connecting rod.
5. Connecting rod as claimed in claim 4, wherein each profiled rib comprises a top truncated flat portion of a predetermined length.
6. Connecting rod as claimed in claim 1, wherein the ribs comprise cross-ribbed ribs in a star configuration.
7. Connecting rod as claimed in claim 4, wherein the ribs comprise a circular mid-rib of predetermined thickness and diameter at the centre of the connecting rod.
8. Connecting rod as claimed in claim 4, wherein the ribs comprise a circular starting rib of predetermined thickness and diameter adjacent one of the lobes of the connecting rod.

9. Connecting rod as claimed in claim 4, wherein each profiled rib is connected to a respective lobe of the connecting rod at either end thereof with a third fillet radius.
10. Connecting rod as claimed in anyone of the claims 1 to 9, wherein the buckling factor of the connecting rod is between 3 to 7, preferably about 4.