Claims:WE CLAIM:

1. A device (200) for coupling a check chain (340) to a lower link (320) of a three-point hitch system of a work vehicle, the device (200) comprising:
a head (210) having a slot (230) configured to receive one end of the check chain (340), and other end of the check chain (340) mounted to rear-side of the work vehicle; and
a shank (220) extending from the head (210) at a first end (220a) towards a second end (220b), the shank (220) receivable by a hole in the lower link (320), the shank (220) is fitted in the hole and the second end (220b) of the shank (220) is welded with the lower link (320).

2. The device as claimed in claim 1, wherein the shank (220) has a tapering profile whereby diameter of the shank (220) increases as it extends from the first end (220a) to the second end (220b), and the hole in the lower link (320) has a corresponding tapering profile to receive the shank (220).

3. The device (200) as claimed in claim 3, wherein angle of taper of the tapering profile ranges from 1° to 45°.

4. The device (200) as claimed in claim 1, wherein the check chain (340) is coupled to the slot (230) via a shackle and pin assembly (360).

, Description:TITLE OF THE INVENTION
A Device for coupling a Check Chain to a Lower Link of a Hitch System

FIELD OF THE INVENTION
The present invention relates to a device for coupling a check chain to a lower link of a three-point hitch system.

BACKGROUND OF THE INVENTION
[001] Work vehicles such as a tractor have various implements like tiller, seeding implement etc. for carrying out field operations. Depending upon type of field operation and contour/type of field or soil condition, the implement must be suitably controlled to perform the required field operation. The implements are connected to the tractor by means of a three-point hitch system, and the hitch system can be operated to raise and lower the implement. The hitch system is typically hydraulically driven and provides position control and/or draft load control.
[002] Figure 1 shows a three-point hitch system 100 as per prior-art. The three-point hitch system 100 includes an upper link 110, pair of lower links 120 and a lift arm 130 for each lower link. The upper link 110 and the pair of lower links 120 allow the implement (not shown) to be adapted to the tractor (not shown). The pair of lower links 120 can be hydraulically lifted vertically by the lift arm 130.
[003] Further, a pair of check chains 140 are provided. Each check chain 140 is attached at one end with each of the lower links 120. The other end is attached to a tractor’s frame. The check chain 140 is primarily configured to reduce or restrict sway in the lateral direction that is created when the implement is following the moving tractor. Unrestricted sway would cause an imbalance of motive forces and may result in the implement flipping over or stalling operations.
[004] Typically, the check chain 140 is connected to the lower links 120 by means of an eyebolt 150. The eyebolt 150 has threads on a shank and is received by a through hole (not shown) with threads in the lower links 120. The eye bolt 150 upon being inserted in the hole is fastened with a flat washer and nyloc nut 150b to couple the eyebolt 150 with the lower links 120. During operations, when the hitch system sways, while the check chain 140 is pulling the lower link 120 to stay in desired position, an immense amount of stress is created on the eyebolt 150 and area of the lower link 120 where the eyebolt 150 is coupled. The lower link 120 attempts to sway in the direction of the implement’s lateral sway whereas the check chain 140 pulls in an opposite direction. Due to such stresses, the eyebolt 150 at a junction can fail and break apart causing the three-point hitch system 100 to become non-functional. Such failures arise primarily due to an inability to transfer loads generated by the check chain 140 to the pair of lower links 120. Further, the flat washer and nyloc nut 150b also contribute significantly to the stress generated at the junction where the eyebolt 150 is coupled with the lower link 120. Additionally, threads on the shank of the eyebolt 150 are under-cut over a period of time and contribute to the stress generated which eventually leads to failure of the eyebolt 150. Further, the eyebolt 150 under load conditions may also rotate which is undesirable.
[005] Thus, there is a need in the art to address at least the aforementioned problems and limitations.

SUMMARY OF THE INVENTION
[006] Accordingly, the present invention in one aspect provides a device for coupling a check chain to a lower link of a three- point hitch system of a work vehicle. The device includes a head and a shank. The head has a slot configured to receive one end of the check chain. The other end of the check chain mounted to rear-side of the work vehicle. The shank extends from the head at a first end towards a second end. The shank is receivable by a hole in the lower link. The shank is fitted in the hole and the second end of the shank is welded with the lower link.
[007] In an embodiment, the shank has a tapering profile whereby diameter of the shank increases as it extends from the first end to the second end. The hole in the lower link has a corresponding tapering profile to receive the shank.
[008] In an embodiment, angle of taper of the tapering profile ranges from 1° to 45°
[009] In an embodiment, the check chain is coupled to the slot via a shackle and pin assembly.

BRIEF DESCRIPTION OF THE DRAWINGS
[010] Reference will be made to embodiments of the invention, examples of which may be illustrated in accompanying figures. These figures are intended to be illustrative, not limiting. Although the invention is generally described in context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments.
Figure 1 illustrates a three-point hitch system as per prior-art.
Figure 2 shows an illustrative representation of a device of the present invention coupling a check chain to a lower link of a three-point hitch system in accordance with an embodiment of the invention.
Figure 3 shows the device in accordance with an embodiment of the invention.
Figure 4 shows a sectional view of the lower link in accordance with an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION
[011] The present invention is directed towards a device for coupling a check chain to a lower link of a three-point hitch system of a work vehicle (not shown). The device prevents damage to the device 200 and/or the lower link during load conditions, especially lateral load conditions.
[012] Figure 2 shows an illustrative representation of a device 200 of the present invention coupling a check chain 340 to a lower link 320 of a three-point hitch system 300 of a work vehicle (not shown). As discussed hereinbefore, the three-point hitch system 300 includes an upper link (not shown), a pair of lower links 320 and a lift arm (not shown) for each lower link 320. The upper link and the lower links 320 allow an implement (not shown) to be adapted to the work vehicle. The lower links 320 can be hydraulically lifted by the lift arm. Further, a pair of check chains 340 are provided. Each check chain 340 is attached at one end with each of the lower links 320. The other end of the check chain 340 is attached to a work vehicle frame. The check chain 340 is primarily configured to reduce or restrict sway in the lateral direction that is created when the implement is following the moving tractor.
[013] The device 200 is a fastening device and is illustrated in greater detail in Figure 3. In an embodiment, the device 200 is made of a medium carbon, high carbon, medium carbon alloyed steel, high carbon allowed steel or a combination thereof. The device 200 comprises a head 210 and a shank 220. The head 210 as shown in the figure has a slot 230 configured to receive the check chain 340. In an embodiment, the check chain 340 is coupled with the slot 230 of the device 200 via a shackle and pin assembly 360. The shackle and pin assembly 360 is simpler to manufacture and assemble with the check chain 340. Alternately, a chain loop can be directly welded with the slot 230.
[014] Further, as shown, the shank 220 extends from the head 210 at a first end 220a towards a second end 220b. The shank 220 is configured to be receivable by a slot/hole (not shown) in the lower link 320 In an embodiment, the shank 220 has a tapering profile whereby diameter of the shank 220 increases as it extends from the first end 220a to the second end 220b, and the hole in the lower link 320 has a corresponding tapering profile to receive the shank 220. In an embodiment, angle of taper of the tapering profile ranges from 1° to 45°. The shank 220 is fitted within the hole and the second end 220b of the shank 220 is welded with the lower link 320. In this regard, the head 210 is inserted into the hole from one side to the other side of the hole, and thereafter, the second end 220b of the shank 220 of the device 200 is welded with the hole. In an embodiment, the fit between the shank 220 can be configured to be a press fit or interference fit or snug fit, and the welding can be carried out via of arc welding and the arc welding can be continuous, stich or tag welding.
[015] Figure 4 shows a sectional view of the lower link 320 with the device 200 adapted to the lower link 320. As can be seen, the tapering profile of the shank 220 and corresponding tapering profile of the hole fits to the device 200 with the hole of the lower link 320. Further, as discussed hereinbefore, the second end of 220b the shank 220 is welded with the hole. The welding is illustrated by reference ‘W’. The welding W of the shank 220 with the lower link 320 prevents rotation of the shank 220 of the device 200 under load conditions. The device 200 with the tapering profile and the welding W to the lower link 320 allows transfer of the loads to the lower link 320, thereby preventing damage to the device 200. Further, tapering profile of the shank 220 of the device 200 will lock lateral movement of the lower link 320 about the shank 220. Further, the device 200 of the present invention creates an integrated joint with the lower link 320 and the loads are transferred to a center of the lower link 320 which is a high strength member and due to which failure is eliminated.
[016] The device 200 of the present invention as discussed hereinbefore does not have any threading on its shank 220, and thus does not require flat washer and nyloc nut for fastening. Due to absence of threads on the shank 220, there is no stress generated on the shank 220 or under-cut over a period of time that contributes to the stress generated which eventually leads to failure of the device 200 and damage to the lower link 320. Further, by eliminating the threading, step of additional machining operation for threading operation is eliminated. Furthermore, the flat washer used/required in the prior-art leads to stress in the shank area and thereby lower link. Moreover, maintaining flatness of the washer is always difficult. By eliminating the usage of flat washer and nyloc nut in the present invention, further failure modes are also eliminated. The device 200 of the present invention eliminates various parts that are required in prior-art and is thus simple in construction and also cost effective.
[017] Advantageously, the device of the present invention transfers load generated by the check chain onto the lower arms which significantly reduces/eliminates stress to the device and also at the junction where the device is coupled with the lower link, thereby eliminating any damage or failure of the device or the lower link.
[018] While the present invention has been described with respect to certain embodiments, it will be apparent to those skilled in the art that various changes and modification may be made without departing from the scope of the invention as defined in the following claims.