Claims:We claim,
1. A mechanism (100) to neutralize a tractor hydraulic system, said hydraulic system having a draft lever (102), a hydraulic piston (104), a hydraulic cylinder (106), a spool engaged with a hitch control valve (108), and a draft actuator (110), said mechanism (100) comprising:
a draft link (118) disposed at one end of a hydraulic cylinder (106); and
a draft linkage mechanism (120) interposed between said draft link (118) and said draft actuator (110),
wherein,
said draft link (118) is actuated by said hydraulic piston (104) to release an applied force on said spool, by moving said draft actuator (110) away from said spool, thereby moving said spool to an original position to neutralize said hydraulic system.
2. The mechanism (100) as claimed in claim 1, wherein said draft linkage mechanism (120) includes at least one spring and at least one draft coupler coupled between said draft link (118) and said draft actuator (110).
3. The mechanism (100) as claimed in claim 1, wherein said hydraulic piston (104) is configured to move out of said hydraulic cylinder (106) for a distance ranging from 10 mm to 20 mm to actuate said draft link (118).
4. The mechanism (100) as claimed in claim 1, wherein said draft link (118) is actuated by a hydraulic force applied by said hydraulic piston (104), whereby said draft actuator (110) linked to said draft link (118) through said draft linkage mechanism moves away from a spool pressed condition to release said spool, so that said spool moves to said original position thereby trapping hydraulic fluid in said hydraulic cylinder (106) to neutralize said tractor hydraulic system, when a hitch linkage is raised to a desired height through said draft lever (102).
5. The mechanism (100) as claimed in claim 1, wherein said mechanism (100) is automatically actuated when said hydraulic piston (104) pushes said draft link (118) away from said hydraulic cylinder (106).
, Description:TECHNICAL FIELD
[001] The embodiments herein relate generally to a hydraulic system adaptable for but not limited to use with position and draft control mechanisms associated with farm tractors, more particularly to a mechanism to neutralize a hydraulic system in a tractor or similar farm vehicles.

BACKGROUND
[002] In conventional hydraulic systems for controlling a draft or position of a tractor hitch mechanism, a pump supplies hydraulic oil to a directional control valve. The directional control valve controls a hydraulic cylinder which acts to control the position of the hitch through a linkage. By this means, an attachment or implement can be raised, held or lowered. In conventional systems, the actual position of the links is obtained by a position sensor and the draft load by a draft sensor. In an electronic control box, the sensor inputs are compared with the set nominal value. Corrections to match the depth setting at the operating panel are triggered electronically to the directional control valve and the hitch moves until the actual value of the sensors matches the nominal value setting.
[003] In such systems a neutral position of the control valve is desirable so that the oil circuit and pump be pressure compensated. It is possible however that during the controlling operations the control valve is moved in its one direction so that even though a throttling of the oil return and a pressure build-up is achieved, this is not sufficient to overcome the back pressure in the working cylinder sufficiently. In such event the pump would tend to continue counteracting an excess pressure and thereby entail a power loss and a rise in oil temperature.
[004] In another approach conventional tractors have a mechanical hitch or rockshaft control unit which has levers or cams which operate the spool of a hitch control valve. Such units have been difficult to assemble since many small parts must be mounted on sleeves or shafts on the inside a rockshaft cylinder housing. Such systems also require a complicated set of linkages to transmit sensed draft force from the upper draft link to the hitch control unit.
[005] Therefore, there exists a need for a mechanism to neutralize a hydraulic system in a tractor, which eliminates the aforementioned drawbacks.

OBJECTS
[006] The principal object of an embodiment of this invention is to provide a mechanism to neutralize a hydraulic system in a tractor.
[007] Another object of an embodiment of this invention is to provide the mechanism to neutralize the hydraulic system which is adapted to avoid hydraulic losses, and overheating of oil.
[008] Yet another object of an embodiment of this invention is to provide the mechanism to neutralize the hydraulic system which is adapted to avoid engine overloading and excessive fuel consumption.
[009] Still another object of an embodiment of this invention is to provide the mechanism to neutralize the hydraulic system which is reliable and inexpensive.
[0010] Yet another object of an embodiment of this invention is to provide the mechanism to neutralize the hydraulic system which is simple in construction, easy to assemble and service.
[0011] These and other objects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.
BRIEF DESCRIPTION OF DRAWINGS
[0012] The embodiments herein are illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the various figures. The embodiments herein will be better understood from the following description with reference to the drawings, in which:
[0013] Fig. 1 depicts a side view of a tractor hydraulic system, according to an embodiment of the invention as disclosed herein; and
[0014] Fig. 2 depicts a perspective bottom view of the tractor hydraulic system, according to an embodiment of the invention as disclosed herein;
[0015] Fig. 3 depicts another perspective bottom view of the tractor hydraulic system showing hitch control valve in raising condition, according to an embodiment of the invention as disclosed herein; and
[0016] Fig. 4 depicts another perspective bottom view of the tractor hydraulic system showing hitch control valve in neutral condition, according to an embodiment of the invention as disclosed herein.

DETAILED DESCRIPTION
[0017] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
[0018] The embodiments herein achieve a mechanism to neutralize a hydraulic system in a tractor. Further, the embodiments herein achieve the mechanism to neutralize the hydraulic system which is adapted to avoid hydraulic losses, and overheating of oil. Furthermore, the embodiments herein achieve the mechanism to neutralize the hydraulic system which is adapted to avoid engine overloading and excessive fuel consumption. Additionally, the embodiments herein achieve the mechanism to neutralize the hydraulic system which is reliable and inexpensive. Moreover, the embodiments herein achieve the mechanism to neutralize the hydraulic system which is simple in construction, easy to assemble and service. Referring now to the drawings, and more particularly to FIGS. 1 through 4, where similar reference characters denote corresponding features consistently throughout the figures, there are shown embodiments.
[0019] Fig. 1 depicts a side view of a tractor hydraulic system, according to an embodiment of the invention as disclosed herein and Fig. 2 depicts a perspective bottom view of the tractor hydraulic system, according to an embodiment of the invention as disclosed herein. In an embodiment, the tractor hydraulic system (200) includes a mechanism (100), a draft lever (102), a hydraulic piston (104), a hydraulic cylinder (106), a spool engaged with a hitch control valve (108), a draft actuator (110), a connecting rod (112), a ram arm (114), a lift arm (116), a draft link (118), and a draft linkage mechanism (120).
[0020] The hydraulic system (200) typically includes the draft lever (102) and a position control lever (not shown) which are mounted towards an operator’s seat of the tractor. Typically, an operator will use the draft lever (102) to cause the circuit to rock a rockshaft until a proper height of the hitch links (not shown) has been secured. When the draft lever (102) is shifted to a raised position by the operator as shown in FIG. 3, the movement of the draft lever (102) is transferred to a first link (122) which is connected to the draft lever (102) at one end. Further, the first link (122) is connected to a bell crank (124) at the other end. The bell crank (124) is rotated by the first link (122) when the draft lever (102) is moved to the raised position. The hydraulic system (200) further includes a draft crank (126) which is attached to the bell crank (124). The motion of the bell crank (124) is transferred to the draft crank (126) as the draft crank (126) makes a physical contact with the bell crank (124). The rotation of the draft crank (126) actuates the draft actuator (110) which in turns presses or pushes a spool of the hitch control valve for a distance X (as shown in Fig. 3) thereby enabling a hydraulic fluid to enter the hydraulic cylinder (106) and push the hydraulic piston (104) from one end to the other end. Further, the hydraulic system (200) includes a hitch control valve (108) which is configured to allow a hydraulic fluid flow to and from the hydraulic cylinder (106). The movement of the hydraulic piston (104) further pushes the connecting rod (112) away from the hydraulic cylinder (106). The connecting rod (112) is connected to the ram arm (114) at one end. The ram arm (114) is rotated for a predetermined angle by the motion transferred by the connecting rod (112). The rotation of the ram arm (114) is further transferred to the lift arm (116) whereby the hitch linkages are raised or lowered according to the motion or shift of the draft lever (102).
[0021] The mechanism (100) to neutralize the tractor hydraulic system includes the draft link (118) which is mounted towards one end of the hydraulic cylinder (106). The draft link (118) is disposed towards the ram arm (114). The hydraulic piston (104) is configured to displace the draft link (118) i.e. the hydraulic piston (104) is configured to push the draft link (118) away from the piston and towards the ram arm (114). The hydraulic piston (104) is pushed by a hydraulic force which in turn pushes the draft link (118). In an embodiment, the draft link (118) is a rod of predetermined shape and size. In an embodiment, the hydraulic piston (104) is configured to move out of the hydraulic cylinder (106) for a distance ranging from 10 mm to 20 mm to actuate the draft link (118).
[0022] The mechanism (100) to neutralize the tractor hydraulic system further includes the draft linkage mechanism (120) which is interposed between the draft link (118) and the draft actuator (110). The draft linkage mechanism (120) further includes at least one spring and at least one draft coupler coupled between the draft link (118) and the draft actuator (110). The movement of the draft link (118) is transferred to the spring and the draft coupler whereby the entire linkage mechanism is shifted backwards. The backwards shift of the linkage mechanism causes the draft actuator (110) to move backwards i.e. away from the spool of the hitch control valve (108).
[0023] The draft link (118) is actuated by the hydraulic force applied by the hydraulic piston (104), whereby the draft actuator (110) linked to the draft link (118) through the draft linkage mechanism moves away from a spool pressed condition to a release position i.e. away from the spool for a distance X+Y (as shown in Fig. 4), so that the spool moves to an original position by trapping hydraulic fluid in the hydraulic cylinder (106). The trapping of the hydraulic fluid in the hydraulic cylinder (106) neutralizes the tractor hydraulic system. The hydraulic system (200) is neutralized when a hitch linkage is raised to a desired height through the draft lever (102). In an embodiment, the mechanism (100) is automatically actuated when the hydraulic piston (104) pushes the draft link (118) away from the hydraulic cylinder (106) thereby neutralizes the hydraulic system (200).
[0024] The technical advantages achieved by the embodiments disclosed herein includes easy assembly and service of the parts, avoids hydraulic losses, overheating of oil, engine overloading and excessive fuel consumption, reliable and inexpensive.
[0025] 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, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.