Patent Description:
For attaching an implement to an agricultural tractor, a three-point hitch is provided on the tractor. The three-point hitch may be connected to the front or the rear portion of the tractor. The three-point hitch has left and right lower links and a top link. An implement is connected to the tractor using these three linkages of the three-point hitch.

For different types of operations, different lengths of the lower links are required. For example, for agricultural operations comparatively longer lower links are required, while for municipal operations such as snowplough, road cleaning, etc. shorter lower links are required. Hence, based on the operations, the length of the lower links needs to be selected. When one type of operation is completed and operator wants to perform another type of operation, first, the set of lower links connected to the hitch needs to be removed. Then, the new set of lower links needs to be connected as per the requirement of second type of operation. The procedure for changing the lower links is time consuming and cannot easily be done by a single person. Also, special tools are required for changing the lower links.

If same length lower links are used for all the operations, it creates a challenge. For example, when longer length lower links which are used in agricultural applications, are used for municipal operations, it induces lateral stresses in the lower links, specially, when they hit a tree or a pole. This may damage the lower links. Also, using longer lower links for a municipal operation makes it difficult for the operator to steer the vehicle. In addition to that, extra ballast needs to be mounted on the rear side of the vehicle.

<CIT> shows a hitch according to the preamble of claim <NUM>.

<CIT> shows a hitch in which an implement attachment link is secured with a locking pin, which is itself secured with a safety pin.

Hence, an object of the invention is to enhance versatility and operability of a hitch for a vehicle, especially an agricultural tractor, of the type mentioned above.

This object is achieved by a hitch for a vehicle with the features of claim <NUM>.

A hitch for a vehicle, in particular for an agricultural tractor, comprises a main frame which is mountable to a vehicle chassis. A pair of left and right lower support arms is pivotably mounted to the main frame at a first or rear end. Each of the support arms at a second or front end comprises a holding means for holding an implement attachment link. A releasable locking device is provided for fixing the implement attachment link to the holding means.

The releasable locking device of the present invention enables the implement attachment links to be easily and quickly removed from the support arms. A new set of implement attachment links can then be easily connected to the support arms. The implement attachment links are selected as per the requirement of the operation and connected to the support arms. As per requirement of the operation, the implement attachment links can be different in lengths or shapes. In transport mode, the implement attachment link is either removed completely or it may be replaced by a shorter implement attachment link. This helps the operator to steer the vehicle with ease. The present invention enables tremendous reduction in time and effort while removing one set of implement attachment links and connecting a new set of implement attachment links. Changing the implement attachment links is comfortably done by hands only, without any tool.

The hitch disclosed in respect of the present invention is a front hitch, however it can be a rear hitch also. The main frame of the hitch is mountable to the tractor. The support arms are pivotably mounted to the main frame with a nut and bolt arrangement. However, it may be mounted by any other fastening method. A hydraulic cylinder is attached to the support arms which can lift and/or lower the support arms whenever required. An electric machine may be used to lift and/or lower the support arms instead of the hydraulic cylinders. The support arms and the implement attachment links are made of a material having high load bearing capacity. The length of the support arms is kept shorter, so that it will not get the additional bending stresses which may be induced because of more length.

Additional embodiments of the hitch are subject to the dependent claims.

According to one of the exemplary embodiments, the implement attachment link is inserted within the holding means. The holding means comprises a slot formed by a first bracket and a second bracket. The implement attachment link is inserted within the slot in order to establish a form fit connection. The form fit connection ensures that there should not be any relative movement between implement attachment link and the support arm. The rectangular profile of the slot further helps to restrain any undesirable movement. The first bracket and the second bracket are made as a single unit. However, it is possible that, it may be made of two different elements connected by a fastening member or welded together. The slot of the support member and the implement attachment link are coated with a wear resistant material. The holes are provided on the first bracket, the second bracket and the implement attachment link. The second bracket of the slot has a flange around the hole on an external side. The flange further has two diametrical apertures. A cap is provided over the hole on the first bracket. The slot and the implement attachment link are rectangular in shape; however, it will be appreciated that it can be a circular shape, a square shape, a polygonal shape, etc..

Furthermore, the locking device comprises a locking pin which is inserted through aligning holes on the first bracket, the second bracket and the implement attachment link. The length of the locking pin is more than the width of the slot. The locking pin has a head at one side and an aperture at the other side. The head has a flat surface which aligns with the cap provided over the hole on the first bracket.

This stops the implement attachment link from rotating within the support arm, ensuring a rigid connection between the implement attachment link and the support arm. Furthermore, the flat surface on the head of the locking pin and the cap provided over the hole on the first bracket aligns the apertures on the locking pin and the diametrical apertures on the flange of the second bracket. A safety pin is inserted through the aligning apertures on the locking pin and diametrical apertures on the flanges of the second bracket. The safety pin does not allow the locking pin to get out of the assembly. The locking pin is inserted through the assembly of the first bracket, the second bracket and the implement attachment link and then retained in that position by the safety pin. The locking pin is also made of a high stress bearable material with resistance coating. The aligning holes and the locking pin are circular in shape; however, it will be appreciated that it may be of any other shape such as a square, a polygonal, a rectangular, etc..

The locking pin can be inserted manually through the aligning holes. The locking pin has a gripping portion which helps operator to comfortably push and pull the locking pin in and out of the aligning holes. The locking pin head is provided with a chain which is connected to the support arm. While changing the implement attachment link, operator sometimes lose the locking pin. The chain attached to the locking pin keeps the locking pin always close to the assembly. This further helps reducing the time for changing the implement attachment link. It is possible that a spring-loaded mechanism can be used to push the locking pin through the aligning holes. The locking device can be any other mechanism such as spring-loaded hook arrangement.

A hitch according to the invention is explained in greater detail below on the basis of the enclosed drawings, wherein matching reference numbers designate components which are structurally identical or comparable in terms of their function. In the drawings:.

<FIG> shows a perspective view of a hitch <NUM> for an agricultural tractor (not shown). The hitch <NUM> comprises a main frame <NUM> which is mounted to the tractor by a fastening member <NUM>. The fastening member <NUM> is a nut and bolt arrangement. A pair of extensions <NUM> is attached on both sides to the bottom of the main frame <NUM> in a pivotable manner. A pair of support arms <NUM> is connected to the pivotable extension <NUM>. Further, an implement attachment link <NUM> is fixed to each of the support arms <NUM>, specifically the implement attachment link <NUM> is inserted within the support arm <NUM>. The implement attachment link <NUM> has a coupling member <NUM> at a free end. The hitch <NUM> also comprises an upper link <NUM>. The implement is attached to the hitch <NUM> using the upper link <NUM> and the coupling members <NUM> on both the implement attachment links <NUM>.

As shown in <FIG>, at a rear end, the extension <NUM> is pivotably connected to the main frame <NUM> by a pivotable connection <NUM>. The extension <NUM> has two holes <NUM> and <NUM> at a front end. The support arm <NUM> has a hole <NUM> and a hole <NUM>. A fastening element <NUM> is inserted through the holes <NUM> on the extension <NUM> and the hole <NUM> on the support arm <NUM>. Another fastening element <NUM> is inserted through the holes <NUM> on the extension <NUM> and the hole <NUM> on the support arm <NUM>. The fastening provided at two places with fastening element <NUM> and <NUM> makes a rigid connection between support arm <NUM> and the extension <NUM>. The fastening element is a nut and bolt arrangement.

A hydraulic cylinder <NUM> is attached to the main frame <NUM> at an upper side, and at a lower side, it is connected to the support arm <NUM> by the fastening element <NUM>. The extension <NUM>, the support arm <NUM> and the hydraulic cylinder <NUM> are held together by the fastening element <NUM>. The hydraulic cylinder <NUM> is used to lift and/or lower the support arm <NUM> through the pivotable connection <NUM>.

As shown in <FIG>, the support arm <NUM> has a holding means <NUM> at a front end. The holding means <NUM> comprises a slot <NUM> formed by the first and second bracket <NUM> and <NUM>. The bracket <NUM> and <NUM> is formed as a single part. Although, it is possible, these can be separate parts connected by welding, nut and bolt, or any other connecting method. The bracket <NUM> has a hole <NUM> and bracket <NUM> has a hole <NUM>. A cap <NUM> is provided over the hole <NUM> of the first bracket <NUM>. A flange <NUM> is provided on an external side of the hole <NUM> on the second bracket <NUM> of the slot <NUM>. The flange <NUM> has two diametrically placed apertures <NUM> to receive the safety pin <NUM>.

As shown in <FIG>, the implement attachment link <NUM> has the coupling member <NUM> at a front end and a hole <NUM> at a rear end. The implement attachment link <NUM> is inserted within the slot <NUM> of the support arm <NUM> to establish a form fit connection. A locking device <NUM> which comprises a locking pin <NUM> is inserted through the aligning holes <NUM>, <NUM> and <NUM> on the first bracket <NUM>, the second bracket <NUM> and the implement attachment link <NUM>, respectively. The locking pin <NUM> has a head <NUM> at one end and an aperture <NUM> at the other end. The head <NUM>, further, has a flat surface <NUM>.

The flat surface <NUM> and the cap <NUM> provided over the hole <NUM> of the first bracket <NUM> stops the implement attachment link <NUM> to rotate within the support arm <NUM>, ensuring a rigid connection. Further, the flat surface <NUM> and the cap <NUM> align the aperture <NUM> of the locking pin <NUM> and the diametrical apertures <NUM> on the flange <NUM> of the second bracket <NUM>. The safety pin <NUM> is inserted through the aligned apertures <NUM> and <NUM>. The safety pin <NUM> does not allow the locking pin <NUM> to come out while in operation.

The locking pin <NUM> and the aligning holes <NUM>, <NUM> and <NUM> at the first bracket <NUM>, the second bracket <NUM> and the implement attachment link <NUM> respectively are circular in shape. However, the person skilled in the art will appreciate other shapes such as rectangular shape, a square shape, a polygonal shape, etc..

The aperture <NUM> and the diametrical apertures <NUM> on the flange <NUM> are circular in shape. However, the person skilled in the art will appreciate other shapes such as rectangular shape, a square shape, a polygonal shape, etc..

The implement attachment link <NUM> and the slot <NUM> are rectangular in shape. However, the person skilled in the art will appreciate other shapes such as circular shape, a square shape, a polygonal shape, etc. The rectangular profile restricts the undesirable movement between the implement attachment link <NUM> and the support arm <NUM>.

A chain (not shown) is with a first end attached to the head <NUM> of the locking pin <NUM>. With a second end, the chain is connected to the support arm <NUM>. While changing the implement attachment link <NUM>, the locking pin <NUM> is removed. The chain attached to the head <NUM> of the locking pin <NUM> keeps the locking pin <NUM> close to support arm <NUM> so that it will not get lost.

As per another embodiment (not shown) of the invention the locking pin <NUM> is inserted through the aligning holes <NUM>, <NUM> and <NUM> by a spring-loaded mechanism.

<FIG> explain the sequence of changing the implement attachment link <NUM>. <FIG> shows a longer implement attachment link <NUM> connected to the support arm <NUM>. For removing the implement attachment link <NUM> shown in <FIG>, first the safety pin <NUM> needs to be removed. Once the safety pin <NUM> is removed, the locking pin <NUM> is free to be removed from aligning holes <NUM>, <NUM> and <NUM>. Once the locking pin <NUM> is taken out of the assembly, the implement attachment link <NUM> can be removed as shown in <FIG>. As per requirement of the operation, the second type of implement attachment link <NUM> is inserted within the slot <NUM> as shown in <FIG>. In this case, the second implement attachment link <NUM> is shorter compared to the other one shown in <FIG>. The locking pin <NUM> is inserted through the aligning holes at the second type of implement attachment link <NUM>, and the holes <NUM> and <NUM> at the first and second bracket <NUM> and <NUM>. Finally, as shown in <FIG> the safety pin <NUM> inserted through the aligning apertures <NUM> and <NUM> holds the locking pin <NUM> in its position.

Claim 1:
A hitch for a vehicle, in particular for an agricultural tractor, comprising a main frame (<NUM>) which is mountable to a vehicle chassis;
a pair of left and right lower support arms (<NUM>) pivotably mounted to the main frame (<NUM>) at a first end, each of the support arms (<NUM>) at a second end comprises a holding means (<NUM>) for holding an implement attachment link (<NUM>), the holding means (<NUM>) comprises a slot (<NUM>) formed by a first bracket (<NUM>) and a second bracket (<NUM>), the implement attachment link (<NUM>) is inserted between the first bracket (<NUM>) and the second bracket (<NUM>) in order to establish a form fit connection;
a releasable locking device (<NUM>) for fixing the implement attachment link (<NUM>) to the holding means (<NUM>), the locking device (<NUM>) comprises a locking pin (<NUM>) which is inserted through aligning holes (<NUM>, <NUM>, <NUM>) in the first bracket, the second bracket and the implement attachment link (<NUM>), wherein the locking pin comprises an aperture (<NUM>), characterized in that the second bracket (<NUM>) has a flange (<NUM>) around the hole (<NUM>) at an external side, wherein there are two diametrical apertures (<NUM>) on the flange (<NUM>) and wherein the apertures (<NUM>) on the flange can align with the aperture (<NUM>) in the locking pin to receive a safety pin (<NUM>).