DESC:FIELD OF INVENTION

The present invention relates to a draft sensing mechanism for tractors. In particular, the present invention relates to a draft sensing mechanism having a unitized configuration. More particularly, the present invention relates to a draft sensing mechanism having a unitized configuration of the extension spindle.

BACKGROUND OF THE INVENTION

The tractor’s three-point hitch consists of the components such as the hydraulic system, attachment points, lifting arms and stabilizers. This three-point hitch includes three movable arms, i.e. two lower arms or hitch lifting arms controlled by the tractor’s hydraulic system to provide lifting, lowering, and even tilting motion to the lower arms; and a movable upper center arm or top link, which is normally not driven by the tractor's hydraulic system.

Each arm has a device for connecting different implements to the hitch by means of attachment holes. The implement also includes posts to fit through these holes and for securing the implement by putting a pin at the ends of these posts. The hitch lifting arms are powered by the tractor's hydraulic system, which is controlled by the operator by using different settings available on it.

The modern three-point hitch systems are often provided with a draft control mechanism, which senses the draft (or the amount of force draft required for pulling the implement) at the lower arms. Subsequently, the hydraulic system automatically raises the arms slightly on detecting an increase in the draft increases or lowers the arms on detecting a decrease in the draft.

The conventional/existing draft sensing mechanism has complex construction having large number of components, which are difficult to assemble and dismantle and thereby require more time for these activities.
There are also problems of sealing against the external contamination and draft linkage adjustment is also very complex and from one side only.

Cast bell crank and machined plunger head cause more wear and tear of assembly.

DISADVANTAGES WITH THE PRIOR ART

However, the main disadvantages with the conventional/existing draft sensing mechanism are briefly discussed above are as follows:

• Includes large no. of components.

• Involves complex assembly/dismantling process.

• Difficult for draft adjustment from all sides.

• Poor sealing against external contamination.

• Spindle not easy to hold in place.

• Higher wear and tear of first seat and spindle due to friction therebetween.

• Reciprocating movement of the spindle assembly not smooth.

• Not suitable for tensile loading.

• Extension spindle slotted, difficult to retain with the spindle.

• Draft linkage has limitation of adjustment from all sides.

• Higher time required for adjustment of draft linkages.

• Higher wear and tear between draft linkages and cast bell crank lever.

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 a draft sensing mechanism for tractors, which is easy to assemble and dismantle.

Another object of the present invention is to provide a draft sensing mechanism for tractors, which is composed of reduced number of parts.

Still another object of the present invention is to provide a draft sensing mechanism for tractors, which is cost-effective.

Yet another object of the present invention is to provide a draft sensing mechanism for tractors, which serves multiple complex functions.

A further object of the present invention is to provide a draft sensing mechanism, which is effective for sealing against external contaminations.

Still further object of the present invention is to provide a draft sensing mechanism, to help in a smooth reciprocating operation of spindle assembly.

Yet further object of the present invention is to provide a draft sensing mechanism, to facilitate spring guidance in compressive and tensile loads.

An additional object of the present invention is to provide a draft sensing mechanism for tractors, which avoids wear of spindle and seat.

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 draft sensing mechanism on tractor and having a unitized extension spindle assembly, wherein the unitized extension spindle assembly facilitates in easy and quick adjustment of the draft in tractors.
Typically, the unitized extension spindle assembly comprises:

• a draft sensing spring housing;

• a draft sensing spring;

• a first seat for supporting draft sensing spring;

• a second seat for draft sensing spring;

• an extension spindle top-link;

• a single-piece extension spindle; and

• a bellow for spring housing;

wherein the bellow comprises an in-built mold ring to make the bellow compact.

Typically, the mold ring snugly fits into a groove provided on the extension spindle to retain the in-built mold ring of the bellow on the extension spindle for effectively sealing the bellow against any external contamination.

Typically, a plurality of holes is provided on the peripheral diameter of the extension spindle to be held in by using a roll pin, irrespective of the slot provided at the end of the extension spindle.

Typically, the single-piece extension spindle comprises integral steps provided on the outer diameter thereof to facilitate smooth reciprocation of the spindle assembly within the spring housing.

Typically, the extension spindle top link is provided with slots at the smaller diameter end thereof to securely retain the extension spindle by means of a slotted pin.

Typically, the extension spindle top link is provided with stepped diameters for guiding the spring in compressive and tensile loadings thereof.

Typically, the head and the stepped diameters of the extension spindle top link are hardened, preferably induction hardened.

Typically, the first spring seat comprises a step of reduced internal diameter to support the head of extension spindle top link during tensile loading thereof.

Typically, the step of reduced internal diameter and inside surface of the first spring seat is hardened, preferably induction hardened.

DESCRIPTION OF THE INVENTION

The unitized extension spindle for the draft sensing mechanism including an improved draft sensing linkage configured in accordance with the present invention substantially reduces the overall number of components thereof.

For example:

• A single unitized extension spindle as compared to earlier 4 separate parts.

• A single-part, first spring seat as compared to the two-part, existing first spring seat.

• In-built moulding ring helps in eliminating one side clamp.

This draft sensing mechanism also exhibits a substantially improved ease of assembly and dismantling due to its improved design and reduced number of parts as indicated above. In addition, the unitized spindle extension particularly serves the following multiple complex functions.

a) Groove helps to retain the bellow intact with the spindle to help in better sealing thereof against any external contamination and to eliminate a side clamp.
b) Holes provided on the peripheral diameter facilitate in holding the spindle (by means of roll pin) irrespective of the slot-position provided at the spindle end.

c) Integrally configured step on the outer diameter helps in eliminating an additional machined part.

d) Facilitates in a very smooth reciprocation of the entire spindle assembly by maintaining the specific machining tolerance on the internal diameter of the spring housing.

Moreover, the main advantages of the extension spindle top link are enumerated below:

i) Slots at end helps in retaining the extension spindle intact with the spindle.

ii) Easy to assemble and dismantle.

iii) Stepped diameter provided to guide the spring both in compressive and tensile loading.

iv) Induction hardening provided on the stepped diameter and spindle head to avoid wear and tear of the spindle and seat.

v) Allen-key slot provided on the face of the spindle head to facilitate dismantling process.

The main advantages of the first spring seat are enumerated below:

a) Number of components reduced from 2 to 1.

b) Step is provided to support the spindle during tensile loading.

c) Induction hardening is done on the internal diameter and step is provided to avoid wear of seat and spindle.

The bellow spring housing is also advantageous due to its particular shape and in-built moulding ring formed at one end thereof to hold, by eliminating a side clamp.

The draft sensing linkage arrangement is also advantageous because of its unique design provided with more adjustment capability and ease of draft- setting.
In contrast to the conventional/existing draft sensing linkage arrangement having a limited side adjustment and which requires longer time for adjustment; the draft sensing linkage arrangement configured in accordance with the present invention is modified by offering adjustment from both sides, without any limitation and by spending much less time for such adjustments.
Moreover, the adjustment is done such that the tolerance variation of the internal linkage can be easily optimized with both side adjustment done externally.

In addition, there is higher wear and tear in bell crank in the conventional/existing draft sensing linkages, because of using a cast bell crank and machined plunger head. Whereas, the modified linkages exhibit less wear and tear due to the linkages being machined and maintained strictly within specified tolerances.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

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

Figure 1a shows a cross-sectional view of the conventional draft sensing mechanism.

Figure 1b shows a perspective view of the conventional draft linkage mechanism.

Figure 2a shows a cross-sectional view of the draft sensing mechanism configured in accordance with the present invention.

Figure 2b shows a perspective view of the draft linkage mechanism configured in accordance with the present invention.

Figure 3a shows a perspective sectioned view of the conventional draft sensing mechanism of Figure 1a, but without bell crank lever.

Figure 3b shows the perspective view of the assembly of the sectioned first spring seat and spacer for conventional draft sensing mechanism.

Figure 3c shows the perspective exploded views of the first sectioned spring seat and spacer of Figure 3b.

Figure 4a shows a perspective sectioned view of the draft sensing mechanism configured according to the present invention however depicted without the bell crank lever.

Figure 4b shows the perspective view of a single component first spring seat.

Figure 5a shows a perspective view of the multi-component extension spindle for the conventional draft sensing mechanism.

Figure 5b shows an exploded view of the multi-component extension spindle of Figure 3d.

Figure 6a shows a sectioned view of the bellow for the conventional draft sensing mechanism.

Figure 6b shows a perspective view of the extension spindle top link for the conventional draft sensing mechanism of Figure 1a.

Figure 7a shows sectioned view of the bellow for mechanism of Fig. 2a.

Figure 7b shows a perspective sectioned view of the improved spindle top link for the draft sensing mechanism of Figure 2a.

Figure 7c shows a perspective view of the unitized extension spindle assembly 160 for the draft sensing mechanism of Figure 2a.

DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS

In the following, the tractor lower-link 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 cross-sectional view of the conventional draft sensing mechanism 10. It includes a draft sensing spring housing 12, a draft sensing spring 14, a first draft sensing spring seat 16, a second draft sensing spring seat 18, an extension spindle 20 and an extension spindle top link 30, bellow 40 for spring housing 12 and bell crank lever 50 connected to a multicomponent spindle assembly.

Figure 1b shows a perspective enlarged view of the conventional draft linkage mechanism 10 depicting a bellow 40 for spring housing 12, a draft plunger support 62, a draft plunger link 64 and bell crank lever 50.

Figure 2a shows another cross-sectional view of the draft sensing mechanism 100 configured in accordance with the present invention. It includes a draft sensing spring housing 110, a draft sensing spring 112 and a slotted pin 114 therefor, a first draft sensing spring seat 116, a second draft sensing spring seat 118, a unitized extension spindle 120 and an extension spindle top link 130, a bellow 140 for spring housing 110 and a bell crank lever 150.

Figure 2b shows a perspective view of the draft linkage mechanism 100 configured in accordance with the present invention depicting an improved draft plunger support 162, an improved draft plunger link 164, an improved turn buckle link draft sensing assembly 166, an improved draft sensing feedback step bolt 168, two standard cotter pins 170 and a standard pin 172.

Figure 3a shows a perspective sectioned view of the conventional draft sensing mechanism 10 of Figure 1a; but depicted without bell crank lever 50. In addition to the second spring seat 18 and the extension spindle 20, it includes a spacer 22 and a clamp 25 with a nut 28 for tightening thereof.

Figure 3b shows the perspective view of the assembly of the sectioned first spring seat 16 and spacer 22 for conventional draft sensing mechanism 10.
Figure 3c shows the perspective exploded views of the first sectioned spring seat 16 and spacer 22 of Figure 3b.

Figure 4a shows a perspective sectioned view of the draft sensing mechanism 100 configured according to the present invention however depicted without the bell crank lever 150. It includes a first draft sensing spring seat 116, a second draft sensing spring seat 118, a unitized extension spindle top link 120 and an extension spindle 130, a bellow 140 for spring housing 110. Here, the improved draft sensing mechanism 100 is provided with an in-built mold ring 142 in the bellow 140.

Figure 4b shows the perspective view of the improved first spring seat with a single component 116 instead of two components (16, 22) conventionally used as shown in Figure 3b. It includes an induction hardened step 1162 provided for supporting the extension spindle 120 and an induction hardened internal diameter 1164. The spring seat 116 is provided with a hardened reduced step 1162 for supporting the head 122 of the extension spindle top link 120. Both the step 1162 and internal diameter 1164 of the spring seat 116 are induction hardened to eliminate any wear and tear thereof.

Figure 5a shows a perspective view of the multi-component extension spindle assembly for the conventional draft sensing mechanism 10, which consists of four components, i.e. first spring seat 16, second spring seat 18, an extension spindle top link 20 (not shown), a clamp 25 tightened by a nut 28, an extension spindle 30.

Figure 5b shows an exploded view of the multi-component extension spindle assembly of Figure 3d and depicts the first spring seat 16, second spring seat 18, clamp 25 tightened by nut 28 and the extension spindle 30.
Figure 6a shows a sectioned view of the bellow 40 for the conventional draft sensing mechanism 10.

Figure 6b shows a perspective view of the extension spindle top link 20 for the conventional draft sensing mechanism 10 of Figure 1a.

Figure 7a shows sectioned view of the bellow 140 for draft sensing mechanism 100 of Fig. 2a configured according to the present invention. Here, one side clamp is eliminated by providing an in-built mold-ring 142 thereon.

Figure 7b shows a perspective view of the improved spindle top link 120 for the draft sensing mechanism 100 of Figure 2a configured according to the present invention. The extension spindle top link is provided with a head 122, a larger stepped diameter 124 and a smaller stepped diameter 126 and slots 128 configured at the end of the extension top link 120 for securely retaining the extension spindle 130 by means of a slotted pin 114 (Figure 2a).

Figure 7c shows a perspective view of the unitized extension spindle assembly 160 for the draft sensing mechanism 100 of Figure 2a configured according to the present invention. A plurality of holes 122 is provided on the peripheral diameter of the extension spindle head to be held in by using a roll pin 128, irrespective of the slot 126 provided at the end of the extension spindle 130.

TECHNICAL ADVANTAGES AND ECONOMIC SIGNIFICANCE

The draft sensing mechanism configured in accordance with the present invention has the following technical and economic advantages:

• Reduced no. of components.

• Easy to assemble/dismantle.

• Unitized spindle extension serving multiple complex functions.

• In-built mold ring fitted in the groove helps in retaining bellow intact with spindle and also omits one side clamp.

• Better sealing against external contamination.

• Better holding of spindle by means of holes provided on the periphery of the extension spindle and using a roll pin.
• Less wear of seat and spindle due to step and internal diameter induction hardening.

• Smoother reciprocating movement of the spindle assembly.

• Stepped diameter supports and guides spring both in tensile and compressive loading.

• Slotted end helps in retaining extension spindle intact with spindle.

• More adjustable draft linkage, which is easy to adjust.

• Adjustment possible from both side, thereby reducing time taken therefor.

• Machined linkages reduce wear due to closely maintained tolerances.

In the previously detailed description, different features have been summarized for improving the conclusiveness of the representation in one or more examples. However, it should be understood that the above description is merely illustrative, but not limiting under any circumstances. It helps in covering all alternatives, modifications and equivalents of the different features and exemplary embodiments.

The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept. Many other examples are directly and immediately clear to the skilled person because of his/her professional knowledge in view of the above description.

These innumerable changes, variations, modifications, alterations may be made and/or integrations in terms of materials and method used may be devised to configure, manufacture and assemble various constituents, components, subassemblies and assemblies according to their size, shapes, orientations and interrelationships. Therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments.
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.

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. In the claims and the description, the terms “containing” and “having” are used as linguistically neutral terminologies for the corresponding terms “comprising”.

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. Furthermore, the use of the term “one” shall not exclude the plurality of such features and components described.

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.

The descriptions of well-known components and manufacturing and processing techniques are consciously omitted in this specification, so as not to unnecessarily obscure the specification.

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. ,CLAIMS:We claim:

1. A draft sensing mechanism (100) on tractor and having a unitized extension spindle assembly, wherein the unitized extension spindle assembly facilitates in easy and quick adjustment of the draft in tractor.

2. Draft sensing mechanism (100) as claimed in claim 1, wherein the unitized extension spindle assembly comprises:

• a draft sensing spring housing (110);

• a draft sensing spring (112);

• a first seat (116) for supporting draft sensing spring (112);

• a second seat (118) for draft sensing spring;

• an extension spindle top-link (120);

• a single-piece extension spindle (130); and

• a bellow (140) for spring housing (110);

wherein said bellow (140) comprises an in-built mold ring (142) to make said bellow compact.

3. Draft sensing mechanism (100) as claimed in claim 2, wherein said mold ring (142) snugly fits into a groove (132) provided on said extension spindle (130) to retain said in-built mold ring (142) of the bellow (140) on said extension spindle (130) for effectively sealing said bellow (140) against any external contamination.

4. Draft sensing mechanism (100) as claimed in claim 1, wherein a plurality of holes (134) is provided on the peripheral diameter of said extension spindle (130) to be held in by using a roll pin (114), irrespective of the slot (128) provided at the end of said extension spindle (130).

5. Draft sensing mechanism (100) as claimed in claim 1, wherein said single-piece extension spindle (130) comprises integral steps (135, 137) provided on the outer diameter thereof to facilitate smooth reciprocation of said unitized extension spindle assembly within said spring housing (110).

6. Draft sensing mechanism (100) as claimed in claim 1, wherein said extension spindle top link (120) is provided with slots (128) at the smaller diameter-end thereof to securely retain said extension spindle (130) by means of a slotted pin (114).

7. Draft sensing mechanism (100) as claimed in claim 6, wherein said extension spindle top link (120) is provided with stepped diameters (124, 126) for guiding said spring (112) in compressive and tensile loadings thereof.

8. Draft sensing mechanism (100) as claimed in claim 7, wherein the head (122) and the stepped diameters (124, 126) of said extension spindle top link (120) are hardened, preferably induction hardened.

9. Draft sensing mechanism (100) as claimed in claim 8, wherein said first spring seat (116) comprises a step of reduced internal diameter (1162) to support said head (122) of said extension spindle top link (120) during tensile loadings thereof.

10. Draft sensing mechanism (100) as claimed in claim 9, wherein said step (1162) of reduced internal diameter and inside surface (1164) of said first spring seat (116) is hardened, preferably induction hardened.

Dated: this 30th day of March 2017. SANJAY KESHARWANI
APPLICANT’S PATENT AGENT