DESC:FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
AND
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10 and rule13)

1. TITLE OF THE INVENTION:
“TRACTOR IMPLEMENT STABILIZER AND HITCHING ARRANGEMENT”

2. APPLICANT:
(a) NAME: MAHINDRA & MAHINDRA LIMITED

(b) NATIONALITY: Indian Company incorporated under the
Companies Act, 1956

(c) ADDRESS: Gateway Building, Apollo Bunder, Mumbai – 400001,
Maharashtra, India.

3. PREAMBLE TO THE DESCRIPTION:
The following specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF THE INVENTION:

The present invention relates to rear three-point hitch system of agricultural tractor, and more particularly it relates to a stabilizer arrangement used to control lateral movement of implement.

BACKGROUND OF THE INVENTION:

Rear three-point hitch system of an agricultural tractor connects the tractor to an implement to be pulled or operated for field operations. Three-point hitch system consists of one upper draft link/ upper link and two lower draft links/ lower links. The upper link and the pair of lower links have articulated ball joints at both their ends each. With these ball joints, one end each of upper link and lower links is connected pivotally to rear end of tractor. The implement mast is connected to the other (rearward) end each of the upper link and the lower links. A pair of lift links connects the pair of lower links to a pair of lift arms. With a suitable hydraulically operated system, the lift arms can be raised, which in turn raise both lower links through lift links. This way, an implement connected to the three-point hitch can be raised in total height (fully) or partially (to any height within its lift-lower range). In addition to this vertical movement, the lower links also tend to move laterally (mostly undesirably) due to side draft imposed by the attached implement during actual field work of tractor. A device called stabilizer is used to control this undesired lateral movement of lower links. Typically one end of the stabilizer is connected to near the middle of the lower link and the other end is connected to a bracket mounted on rear axle housing of the tractor.

Strut stabilizer and chain stabilizer are the two types of stabilizer used in practice / conventionally. Function of the stabilizer is to bear tensile and/ or compressive force imposed by the lateral draft exerted by the implement and control lateral sway of the implement. Overall length of the stabilizer is adjustable, so that the lower links can be moved laterally to suit width of the implement and connect with the implement through ball joints. A strut stabilizer consists of inner and outer rectangular or circular sliding members for setting its length. Through-holes at certain pitch are provided on these members. After setting length of the stabilizer, the inner & outer members are locked in position by inserting a headed pin through these holes. During field operations such as mold board ploughing or harrowing, lower links are subjected to high lateral load along with longitudinal load. Usually this lateral load acts from right to left side of the tractor. Due to this lateral load, right hand side strut stabilizer is subjected to tensile force and left hand side strut stabilizer to compressive force. Thus a strut stabilizer can bear both tensile and compressive forces in field operation of tractor.

A chain stabilizer is an assembly of link chain, threaded male-female members and lock-plate or lock-nut for adjusting overall length. A chain stabilizer can bear only tensile force (for the obvious reason of the chain part of it being collapsible).

After hitching implement to three-point hitch and setting stabilizers to a required length, when lower links are raised or lowered, it is necessary that pivot points of lower links and stabilizers are co-axial. As mentioned in previous paragraph, the pivot point of stabilizer is on a bracket mounted on rear axle housing. As against this, the pivot point of lower links is typically on transmission housing directly, or on a bracket mounted on transmission housing. This arrangement does not ensure exact co-axial positioning of lower links and stabilizers together. This has following disadvantage. When overall length of stabilizers are set to achieve desired lateral sway of implement at a particular vertical position of lower links, the amount of sway increases or decreases when lower links are lifted or lowered from the position. This sometimes results into “more sway” than set earlier or “zero sway” of three-point hitch. Zero sway of three-point hitch makes stabilizers absolutely tight, which sometimes may result into damage of the “weak” link in stabilizer.

There are some stabilisers which restrict the movements of lower links of the hitching arrangement when the arrangement is raised, as in DE4113859. DE4113859 relates to a device for stabilization of the lower link of a three point hitch on a tractor, consisting of a rod, whose one end is connected to the lower link via a joint and whose other end is guided in the housing of a support, which is connected to the tractor, the bar with a traversed by the beam joint leads and inside the housing a pivotable and pivotable by means of a lever which is adjustable by means of a Bowden cable from the tractor driver, lockable travel limiting device for the lower arm remote from the end of the rod has the form of a curved component.

GB2425929 discloses a hydraulic stabilizer for lower hitch arms of a three point hitch of agricultural vehicle. The stabiliser of GB’929 is connected to only one of the two lower arms that are pivotable about a vertical axis for controlling lateral movement of the two lower arms. The stabiliser comprises a hydraulic jack having an actuating rod connected to a double-acting piston separating two variable volume working chambers which are connected to communicate with one another through a selectively operable valve.

SUMMARY OF THE INVENTION:

In view of the drawbacks mentioned, primary objective of the present invention is to provide a stabilizer of hitching arrangement in such a way that pivot points of lower links and chain stabilizers are exactly or substantially co-axial,. This would ensure that lateral sway of three-point hitch set at particular vertical position of the three-point hitch remains the same when the three-point hitch / lower links is raised or lowered from that vertical position.
Another objective of the invention is to avoid possible damage of “weak” link during lowering or lifting of three-point hitch.

Yet another objective of the invention is to minimize complexity and/or number of components required for three-point hitch system. Lesser number of components/ reduced complexity would reduce assembly time. Lesser components and assembly time would reduce product cost and labor cost and improves easy serviceability.

The invention obviates need of separate brackets and hardware for mounting of these brackets for hitching one end of stabilizer.

Yet another objective of the invention is to provide a stabilizer arrangement within size / space constraints with respect to available space in existing tractor design/ model, without disturbing design and arrangement of surrounding parts.

Accordingly, there is provided a stabiliser assembly in a three-point hitch arrangement to restrict lateral sway of the hitch arrangement during lowering or raising the three-point hitch. The stabilizer comprises a pair of stabilisers, and a pair of pivot links. The stabiliser is connected to a pair of lower links of the three-point hitch arrangement in a criss-cross manner, thereby adjusting pivot points of the lower links and the stabiliser co-axially or substantially co-axially during lowering or raising the three-point hitch.

BRIEF DESCRIPTION OF FIGURES:

FIGURE 1 shows rear portion of a tractor having three-point hitch arrangement with the present invention.
FIGURE 2 shows close-up of plan view of hitching of lower links and stabilizers.
FIGURE 3 shows right hand side view of three-point hitch of tractor.
FIGURE 4 shows exploded view of lower link mounting plates, lower links & members of stabilizer of present invention.

NOMENCLATURE OF COMPONENTS
1 – Driver’s seat
2 – Rear traction wheels
3 – Transmission housing
4 – Hydraulic lift housing
5 – Left hand side rear axle housing
6 – Right hand side rear axle housing
7 – Left hand side hydraulic lift arm
8 – Right hand side hydraulic lift arm
9 – Left hand side lift link (with fixed length)
10 – Right hand side lift link (with adjustable length)
11 – Left hand side bracket for mounting lower link
12 – Right hand side bracket for mounting lower link
13 – Upper draft link/ upper link
14 – Lower draft link/ lower link
15 –Stabilizer
16 – Pivot link (child part of stabilizer assembly)
17 – Lynch pin
18 – Headed pin
19 – Hydraulic lift shaft
20 – Locking clip

DESCRIPTION OF PREFERRED EMBODIMENT:
The present invention discloses stabiliser in a three-point hitch arrangement to restrict lateral sway of the hitch arrangement during lowering or raising the three-point hitch comprising, a pair of stabiliser, and a pair of pivot links, wherein the stabiliser is connected to a pair of lower links of the three-point hitch arrangement in a criss-cross manner, thereby adjusting pivot points of the lower links and the stabiliser co-axially or substantially co-axially during lowering or raising the three-point hitch.

FIGURE 1 shows rear portion of an agricultural tractor having rear traction wheels 2 and driver’s seat 1. Rear traction wheels are bolted onto rear axles (not shown in figures), which are housed inside rear axle housings 5 and 6 (each on either sides). These rear axle housings 5 and 6 are bolted onto left and right hand side respectively of transmission housing 3. Hydraulic lift housing 4 is bolted onto the top of transmission housing 3. Upper draft link 13 is hitched with hydraulic lift housing 4 and secured in place with a lynch pin 17. Hydraulic lift arms 7 and 8 are supported on two ends (LHS and RHS) of Hydraulic lift shaft 19. At their upper ends near to the tractor rear side, lift links 9 and 10 have built-in articulated ball joints. With headed pin 18 and locking clip 20, upper ball joint of left hand side lift link 9 is connected to left hand side hydraulic lift arm 7 and lower end is connected to lower link 14. Similarly, right hand side lift link 10 is connected to the right hand side hydraulic lift arm 8 and right hand side lower link 14. The stabilizer assembly of the present invention consists of a pair of stabilisers 15 and a pair of pivot assembly. A pair of pivot links 16 and the lower links are hitched onto the pins welded on brackets 11 and 12. A pair stabilizers 15 is connected to the lower links 14 and each of the pivot links 16 in a criss-cross manner. The stabilisers 15 may be a chain stabilizer, a strut stabilizer or combination thereof.

FIGURE 2 is a close-up of plan view, in which 11 is lower link mounting left hand side bracket bolted onto the left hand side of transmission housing 3 and 12 is lower link mounting right hand side bracket bolted onto the right hand side of the transmission housing 3. Mounting pins, welded onto these brackets 11 and 12 for mounting of lower links, are co-axial.

FIGURE 3 is right hand side view of three-point hitch.
Description hitherto are not part of the present invention.

FIGURE 4 is exploded view of the present invention.

In a preferred embodiment, Pivot link 16 is a child part of proposed stabilizer assembly of the present invention. Pivot link 16 and lower links 14 are hitched on the pins welded onto the brackets 11 and 12. Lynch pins 17 ensure locking of pivot links 16 and lower links 14 in place. Other ends of the stabilizers 15 are connected to opposite side (cross) lower links 14.

With this inventive arrangement, as the mounting pins of the brackets 11 and 12 are co-axial, the ends of pivot links 16 of the proposed stabilizer assembly of the present invention and also the lower link 14 ends mounted onto these pins become co-axial, thus ensuring no stresses on the stabilizers 15.

Advantageously, the present invention increases durability and reliability to the hitching arrangement, also increasing smoothness in the operation thereof. It also obviates need of separate brackets and hardware for mounting of these brackets for hitching one end of stabilizer.

The foregoing description of the invention has been set merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiment(s) incorporating the spirit and substance of the invention may occur to person skilled in the art, the invention should be construed to include everything within the scope of the disclosure. ,CLAIMS:1. A stabiliser assembly in a three-point hitch arrangement to restrict lateral sway of the hitch arrangement during lowering or raising the three-point hitch comprising a pair of stabiliser 15, and a pair of pivot links 16, wherein said stabiliser is connected to a pair of lower links 14 of said three-point hitch arrangement in a criss-cross manner, thereby adjusting pivot points of said lower links 14 and said stabiliser co-axially or substantially co-axially during lowering or raising the three-point hitch.

2. The stabiliser assembly as claimed in claim 1, wherein one end of each stabiliser 15 is connected to one of said pivot link 16 and the other end of each stabiliser 15 is connected to diagonally opposite lower link 14 in a criss-cross manner.

3. The stabiliser assembly as claimed in claim 1, wherein said pivot link 16 and said lower links 14 are hitched on co-axial pins welded onto plurality of brackets 11 and 12, thereby ensuring co-axial alignment of pivot points of said lower links and said stabiliser.

4. The stabiliser assembly as claimed in claim 1, wherein pivot links 16 and lower links 14 are locked in place by means of lynch pins 17.

5. The stabiliser assembly as claimed in claim 1, wherein stabiliser 15 is of chain type, strut type or combination thereof.