Claims:We claim:

1. A shear pin assembly for the combine harvester to protect the failure of drive elements of the grain elevator due to overload, comprising of : a primary grain elevator (100) having a top auger (101) and a bottom auger (102), wherein said bottom auger (102) having a first end (103) and a second end (104), wherein said second end (104) of the bottom auger of the primary elevator is coupled to the top auger (101) of the primary grain elevator (100) by means of interfacing drive elements (105a); a secondary grain elevator (106) having a top auger (107) and a bottom auger (108), wherein said bottom auger (108) having a first end (109) and a second end (110), wherein said second end (110)of the bottom auger of the secondary grain elevator is coupled to the top auger (107) of the secondary grain elevator (106) by means of interfacing drive elements (105b), wherein said primary (100) and secondary (106) grain elevator transports the grains from the thresher (111) to the grain storage tank (112) of the combine harvester, wherein said first end (109) of the bottom auger (108) of the secondary grain elevator is linked to the first end (103) of the bottom auger (102) of the primary grain elevator via a rotating coupling belt (113); and atleast a shear pin assembly (114), assembled at the first end (103) of the bottom auger of the primary elevator assembly (100).
2. A shear pin assembly for the combine harvester according to claim 1, wherein the said shear pin assembly (114) comprises of: a secondary drive sprocket (115); a primary driven sprocket (116); and a shear pin (117), connecting the said secondary drive sprocket (115) and the said primary driven sprocket (116).
3. A shear pin assembly for the combine harvester according to claim 1 and 2, wherein the said shear pin assembly (114) additionally comprises of a split pin (118), which retains the said shear pin (117) in its position; and a parallel key (119), which transfers the drive from the said secondary drive sprocket (115) to the said first end (103) of the bottom auger of the primary elevator assembly (100).
4. A shear pin assembly for the combine harvester according to claim 1 and 2, the said primary grain elevator assembly (100) and the said secondary (106) grain elevator assembly, gets isolated from the drive components through the breakage of the said shear pin (117), while encountering overload.
5. A shear pin assembly for the combine harvester according to claim 1 and 2, wherein said shear pin assembly (114) protects multiple grain elevator assemblies in a combine harvester.
6. A shear pin assembly for the combine harvester according to claim 1 and 2, wherein material of the said shear pin is compatible with the material of the drive elements, this minimize the irritant caused by the frequent breakage of the said shear pin.
7. A shear pin assembly for the combine harvester according to claim 1 and 2, wherein said shear pin (117) is mounted in axial orientation with respect to the drive shaft, this enables easy replacement and maintenance of the shear pin.
8. A shear pin assembly for the combine harvester according to claim 1, wherein said shear pin assembly for the combine harvester is provided with a provision for accommodating a plurality of shear pins to protect a plurality of rotating drive elements in the combine harvester.
9. A shear pin assembly for the combine harvester as claimed in any of the preceding claims, protects the failure prevention of the drive elements of the grain elevator assemblies of the combine harvester which frequently encounters excessive loads.

, Description:FIELD OF INVENTION:
The present invention relates to farm implements, more particularly the present invention relates to a shear pin assembly for the combine harvester to safeguard the drive elements of the grain elevator.
BACKGROUND OF THE INVENTION:
Agricultural machinery especially farm implements such as combine harvester are provided with many drive components including roller, shaft, gear drive, belt drive and bevel gears for driving the grain elevator system. These component needs to be safeguarded from being damaged due to overload during the operation. During machine operation impurities or grains frequently get choked into the drive components located in the grain elevator assembly which makes it more difficult to operate the machine and also causes damage to the drive components. It is well known that overload can cause various other consequences, such as jamming or sudden breakdown of the machinery, damage of coupling & other motor elements, damage to drive components, in serious cases can cause severe accidents to operating personnel as well. There are numerous method to prevent the damages caused due to overload condition, but most commonly adopted one is the shear pin assembly mechanism because of its simple structure, reliability, easy maintenance, low cost and many other advantages. A shear pin is a component which form the weakest link in the drive train. These shear pins are designed such that it breaks when it experiences a preselected or predetermined overload limit, so that extreme shock loads will have the effect of breaking the shear pin before damaging the coupling or other components. Once the operating machine encounters a predetermined overload limit, the shear pin under the action of shear will automatically cut, and cut off the power output and stops the operation of drive components, thereby protecting them from getting damaged.
In general, two members of the drive-side are connected together via a shear pin. The shear pin is provided with a head and a shank with a passageway extending axially along the length of the shear pin. A hole in each of the driving and the driven members is provided to receive the shear pin. And if the overload from the drive-side member is applied, the shear pin is broken, by suppressing the overload transmission to the driving-side member, which may cause damage to the peripheral devices. Shear pin is then broken so it becomes impossible to transmit power at the connecting portion. In general, the shear pin must be capable of withstanding a certain shear force on the pin without failure but at a predetermined shear force the pin must shear so that the components connected by the shear pin will be able to separate.
However, conventionally existing shear pin overload protection assembly has lot of limitations, shear pins are operable only at static load conditions, under large fluctuating load conditions the shear pin assembly gets disturbed. Bearing stress of the shear pin material should be compatible with that of the bearing stress of the component material, so that any early failure/damage of the components are prevented. Any interference fit of the shear pin with the drive elements may cause bending stresses on the shear pin and results in bending fatigue failures of the shear pins even before experiencing the overload. In addition the shear pins requires frequently scheduled maintenance & replacement. Further other dimensional constraints such as requirement of stepped shear pin in certain cases, may incur higher machining cost and increased number of coupling parts. Hence there exists a need in the art to provide a shear pin coupling which permits ease of assembly and replacement of the shear pins while at the same time effectively protects the drive components of the grain elevator assembly of the combine harvester

EP2580955 discloses an agricultural device for controlling the unloading of grain including an unloader conveyor having an inlet end for receiving grain, and an opposite outlet end for discharging the grain. The said unloader drive comprises a shear pin and the predetermined shear value is less than the shear force capacity of the shear pin associated with simultaneous operation of the substantially vertical unloader conveyor segment and the substantially horizontal unloader conveyor segment in the engaged mode. The said shear pin is designed to protect the horizontal and the vertical auger together and the possibility of failed shear pin to get stuck between augers is high.
US2763362 relates to augers for removing grains from storage bins. Further the said auger is flexible which can be bent in the shape of the arc of a circle to fit against the inner wall of a circular storage bin. The augers and shaft are secured by a shear pin Once the shear pin of any auger is failed the other augers transport grains leading to failure of other shear pins and thereby inducing other failure modes. Further the shear pins are mounted in radial direction which leads to difficulty in replacing the failed shear pin.
CN105042003 provides a multi-stage overload protection type shear pin for mechanical overload protection, comprising of : a driving wheel, a driven wheel, a displacement sensor, a control unit, and shear pins in various stages. When there exists a overload phenomenon, the shear pins in various stages will be sheared in sequence, then displacement deviation is produced when the driving wheel continues to rotate and the driven wheel does not rotate, the displacement sensor is triggered, and finally the control unit can achieve the alarm, halt and other protection functions according to settings. Use of multiple shear pins at various stages in radial direction makes the replacement of the shear pins a tedious task.
US4186570 discloses a shear pin assembly for shaft coupling which is elongated circular cylindrical shear pin having a central groove which is held at its ends in split, tapered bushings received in tapered outer bushings press-fitted into bores in flanges of the two coupling halves. A loading bolt is threaded in each end of the shear pin and a head of the bolt bears against a loading plate which in turn is seated against the split inner bushing to force the inner bushing into place to rigidly grip the ends of the shear pin.
KR100920112000 provides a motor overload preventing device of a conveyor system to prevent the overload of the motor by making a shear pin, in charge of power supply, break down when a foreign material is stuck in a conveyor. This patent addresses the protection of the motor from load coming from a sprocket. Since the pin is oriented in radial fashion to the shaft, the removal of shear pin after shear will be difficult.
CN103569600 relates to a safety protection device of a chain conveyor, comprising a driven chain wheel, a shaft sleeve, a conveying chain wheel, a shaft and a pillow block bearing. A safety pin penetrates the pin hole of the driven chain wheel and the pin hole of the shaft sleeve; the driven chain wheel and the shaft sleeve are connected together through the safety pin and fixed on a clamping plate which is arranged on the end surface of the driven chain wheel to be inserted into a spigot of the safety pin; a baffle plate is in fixed threaded connection with the end portion of the shaft. According to the safety protection device of the chain conveyor, the safety pin can be sheared off during overload to protect a gear motor from being damaged. Since the shear pin is oriented in radial fashion to the shaft, the removal of safety pin after shear becomes difficult.
All of the above cited prior-arts the shear pin is oriented in radial direction which makes them difficult in handling during replacing and maintenance. Further none of the prior-art documents address the problem associated with the drive components of the grain elevator system in combine harvesters. Therefore there exists a need in the art to provide a shear pin coupling which permits ease of assembly and replacement of the shear pins while at the same time effectively protects the drive components of the grain elevator assembly of the combine harvester which frequently encounters an excessive load due to grain choking, wet crop or failure of blower etc.
The present invention provides a shear pin assembly for the combine harvester to protect/safeguard the drive elements of the grain elevator which frequently encounters an excessive load due to grain choking. The present invention provide a provision for accommodating multiple shear pins which protects a series of rotating drive elements in the combine harvester. In the present invention the selected material of the shear pin is compatible to the material of the drive elements so that the irritant caused by the frequent breakage of shear pin is minimized. Further the mounting of the shear pin in axial orientation makes the replacement and maintenance of the shear pin easy, economical and less time consuming.

OBJECTIVE OF THE INVENTION:
The main objective of the present invention is to protect/safeguard the drive elements of the grain elevator system in a combine harvester by providing a shear pin assembly.
Another objective of the present invention is to protect the drive elements of the grain elevator system which frequently encounters an excessive load due to grain choking by providing a shear pin assembly.
Yet another objective of the present invention is to provide a single shear pin assembly to protect multiple grain elevator assemblies in a combine harvester together.
Still another objective of the present invention is to provide a provision for accommodating multiple shear pins which protects a series of rotating drive elements of the grain elevator system in the combine harvester.
Additional objective of the present invention is to minimize the frequent breakage of the shear pin by selecting the most compatible material for the shear pins and drive elements.
Added objective of the present invention is to provide a serviceability of the shear pin to comfort an effortless method to replace the failed shear pins in the combine harvesters.

SUMMARY OF THE INVENTION
The present invention provides a shear pin assembly for the combine harvester to protect/safeguard the drive elements of the grain elevator from overload, comprises of : a primary grain elevator (100) having a top auger (101) and a bottom auger (102), wherein second end (104) of the bottom auger of the primary elevator is coupled to the top auger (101) by means of interfacing drive elements (105a); a secondary grain elevator (106) having a top auger (107) and a bottom auger (108), wherein second end (110)of the bottom auger of the secondary grain elevator is coupled to the top auger (107) of the secondary grain elevator (106) by means of interfacing drive elements (105b), wherein said first end (109) of the bottom auger of the secondary grain elevator (106) is linked to the first end (103) of the bottom auger of the primary grain elevator (100) via a rotating coupling belt (113); and atleast a shear pin assembly (114), assembled at the first end (103) of the bottom auger of the primary elevator assembly (100). The said shear pin assembly (114) introduced in the primary grain elevator assembly (100) of the combine harvester consists of a shear pin (117) connecting the driven sprocket (116) of the primary elevator assembly and its respective drive shaft/secondary drive sprocket (115). Whenever the drive components of the elevator assemblies encounter an excessive load due to grain choking, wet crop or failure of blower etc, the primary (100) and the secondary (106) grain elevator assemblies are isolated from the drive through the breakage of the shear pin (117). Further the present invention minimizes the frequent breakage of the shear pin by selecting the most compatible material for the shear pins and drive elements.
An embodiment of the present invention provides a provision for accommodating multiple shear pins to protect a series of rotating drive elements of the grain elevator system in the combine harvester. The present invention also provides a serviceability of the shear pin to comfort an effortless method to replace the failed shear pins in the combine harvesters. Further mounting of the shear pin is axial orientation makes the replacement and maintenance of the shear pin simple, easy, reliable, economical and less time consuming.
BRIEF DESCRIPTION OF THE DIAGRAM
Fig 1. shows the combine harvester drive layout.
Fig 2. depicts the layout of the combine harvester with grain elevator system.
Fig 3. illustrates the perspective view of the grain elevator system with shear pin assembly of the present invention.
Fig 4. represents the shear pin assembly of the present invention.

DETAILED DESCRIPTION OF THE INVENTION
The present invention as embodied by the "shear pin assembly for combine harvester", succinctly fulfils the above-mentioned need(s) in the art. The present invention has objective(s) arising as a result of the above-mentioned need(s), said objective(s) being enumerated below. In as much as the objective(s) of the present invention are enumerated, it will be obvious to a person skilled in the art that, the enumerated objective(s) are not exhaustive of the present invention in its entirety, and are enclosed solely for the purpose of illustration. Further, the present invention encloses within its scope and purview, any structural alternative(s) and/or any functional equivalent(s) even though, such structural alternative(s) and/or any functional equivalent(s) are not mentioned explicitly herein or elsewhere, in the present disclosure. The present invention therefore encompasses also, any improvisation(s)/modification(s) applied to the structural alternative(s)/functional alternative(s) within its scope and purview. The present invention may be embodied in other specific form(s) without departing from the spirit or essential attributes thereof.
Throughout this specification, the use of the word "comprise" and variations such as "comprises" and "comprising" may imply the inclusion of an element or elements not specifically recited.
The present invention provides a shear pin assembly for the combine harvester to protect/safeguard the drive elements of the grain elevator from overload, comprises of : a primary grain elevator (100) having a top auger (101) and a bottom auger (102), wherein said bottom auger (102) having a first end (103) and a second end (104), wherein said second end (104) of the bottom auger of the primary elevator is coupled to the top auger (101) of the primary grain elevator (100) by means of interfacing drive elements (105a); a secondary grain elevator (106) having a top auger (107) and a bottom auger (108), wherein said bottom auger (108) having a first end (109) and a second end (110), wherein said second end (110)of the bottom auger of the secondary grain elevator is coupled to the top auger (107) of the secondary grain elevator (106) by means of interfacing drive elements (105b), wherein said primary (100) and secondary (106) grain elevator transports the grains from the thresher (111) to the grain storage tank (112), wherein said first end (109) of the bottom auger (108) of the secondary grain elevator is linked to the first end (103) of the bottom auger (102) of the primary grain elevator via a rotating coupling belt (113); and atleast a shear pin assembly (114), assembled at the first end (103) of the bottom auger of the primary elevator assembly (100).
The said shear pin assembly (114) comprises of a secondary drive sprocket (115), a primary driven sprocket (116), and a shear pin (117) coupling the said secondary drive sprocket (115), a primary driven sprocket (116). The shear pin assembly further comprises of a split pin (118), the said split pin retains the said shear pin (117) in its position, and a parallel key (119), said parallel key (119) transfer the drive from the said secondary drive sprocket (115) to the said first end (103) of the bottom auger of the primary elevator assembly (100).
The said shear pin assembly (114) introduced in the primary grain elevator assembly (100) of the combine harvester consists of a shear pin (117) connecting the driven sprocket (116) of the primary elevator assembly and its respective drive shaft/secondary drive sprocket (115). Whenever the drive components of the elevator assemblies encounter an excessive load due to grain choking, wet crop or failure of blower etc, the primary (100) and the secondary (106) grain elevator assemblies are isolated from the drive through the breakage of the shear pin (117).
In the preferred embodiment, wherein the material of the shear pin (117) is selected such that it is compatible with the material of the drive elements, so that the irritant caused by the frequent breakage of shear pin is minimized.
In the preferred embodiment of the present invention, a single shear pin assembly (114) protects the multiple grain elevator assemblies in a combine harvester together.
In the preferred embodiment of the present invention, wherein said shear pin (117) is mounted in axial orientation with respect to the drive shaft, enabling easy replacement and maintenance of the shear pin.
In an embodiment of the present invention, the shear pin assembly (114) for the combine harvester is provided with a provision for accommodating a plurality of shear pins to protect a plurality of rotating drive elements in the combine harvester.
The shear pin assembly of the present invention protects and ensures the failure prevention of the drive elements of the grain elevator assemblies of the combine harvester which frequently encounters excessive loads due to grain choking. Further the present invention minimizes the frequent breakages of the shear pin by selecting the most compatible material and also protects the series of rotating drive elements of the grain elevator system in the combine harvester by accommodating a plurality of shear pins in the grain elevator system. Additionally the serviceability of the shear pin to comfort an effortless method to replace the failed shear pins in the combine harvesters is effected by using the shear pin assembly of the present invention. Further mounting of the shear pin is axial orientation makes the replacement and maintenance of the shear pin simple, easy, reliable, economical and less time consuming.
It will be apparent to a person skilled in the art that the above description is for illustrative purposes only and should not be considered as limiting. Various modifications, additions, alterations, and improvements without deviating from the spirit and the scope of the invention may be made by a person skilled in the art.