Yam harvester connected to a tractor

Abstract

To improve a rotating conveyor device to prevent damage or breakage of Chinese yams caused by compression of culture soil blocks and back pressure.SOLUTION: A Chinese yam harvester connected to a tractor comprises: a mounting frame attached to the rear part of the tractor by a three-point link; a machine frame body connected to the mounting frame; and a support bar that is fixed to a digging blade body and connected to the machine frame body. The machine frame body is configured to be raised and lowered by the three-point link. In a harvester that grips the Chinese yam together with the culture soil around the Chinese yam in a block shape and excavates the Chinese yam while lifting it rearward, a rotating conveyor device is placed on the upper surface of a digging frame. The rotating conveyor device comprises a plurality of rows of transverse rollers on a pair of support frames, and an endless belt stretched over the rollers. The tip ends of the support frames are formed to be foldable upward, and packing covers that are always pressed into close contact are provided at both ends of the endless belt.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a harvester that is connected to the rear of a tractor, plows the digging blade into the lower end of the yams, holds them together with the cultivated soil around them in a block shape, and lifts them backward. In particular, the present invention relates to a packing cover that prevents soil from entering the rotating conveyor device when the yams are lifted up. [Background technology]

[0002] Various types of yam harvesting devices have been proposed. Yam grows underground to a depth of about one meter, and during harvesting, the yam is prone to breaking and the outer surface of the yam is easily scratched. A commonly filed harvester, JP 2006-25601 A (Patent Document 1), proposes a digging blade that plows into the bottom of the yam, holds it together with the surrounding soil in a block shape, and lifts it backward to dig up the yam. The publication discloses a configuration for a "potato digging device having a pair of plow members connected to the rear of a tractor that dig up the cultivated soil on both sides of the potato as the tractor moves forward, and a digging blade body pivotally connected to the lower center of the pair of plow members, with the front portion forming a cutting edge and the rear portion tilting upward. The connection between the digging blade body and the plow members is supported by a pair of connecting bars, one end of which is fixed to the lower end of the plow members and the other end of which is pivotally attached to a support shaft provided on the backside of the digging blade body, and the connecting bars are arranged so that they are completely hidden by the backside of the digging blade body." The effect of this is that the back pressure resistance from the excavated soil experienced by the tractor when towing the potato digging device is reduced, making it possible to tow the device with a relatively small tractor. The same applicant has also filed Patent Application No. 2023-34095 for technology relating to a harvester that "plows the digging blade into the lower end of the yam, holds it together with the cultivated soil around it in a block shape, and lifts it backward, and in particular, a soil pressure reducing rotating conveyor device that reduces scratches caused by soil pressure when the yam is lifted backward." [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-25601 A [Patent Document 2] Patent application 2023-34095 Summary of the Invention [Problem to be solved by the invention]

[0004] The aforementioned first patent document is suitable for high-speed work using large, 100- to 150-horsepower tractors, which have become popular in recent years. However, when the digging blade, which is embedded in the bottom of a grown yam, slides backward through the yam, it compresses the cultivated soil block, and the back pressure can cause soil to break down and scratch the surface of the yam. The second patent document features a rotary conveyor device in the digging section to further reduce the compression and back pressure of the cultivated soil block caused by the configuration of the first patent document. However, when using a large, 100- to 150-horsepower tractor, which has become popular in recent years, to dig into the soil at a depth of about 1 meter, soil and sand can get in through gaps in the endless belt of the rotary conveyor device, making long-term operation difficult. [Means for solving the problem]

[0005] The present invention 、 The soil and sand escaped through the gaps in the rotating conveyor device in the excavation section. IntrusionThis causes a problem that makes it difficult for the endless belt to rotate, and to solve this problem, a mounting frame is attached to the rear of the tractor by a three-point link formed by a top link and left and right lower links, The aforementioned The machine frame is connected to the mounting frame. The aforementioned A support bar is connected to the machine frame, and the digging blade body, which is made up of a blade body, a digging plate frame, and a vibration plate, is fixed to the support bar. The aforementioned The machine frame 3. It is configured to be able to be raised and lowered by point links, and Digging In a harvester that digs up yams by plowing a digging blade into the lower end of the yams, holding the yams together with the cultivation soil around them in a block shape and lifting them backward, a rotating conveyor device is placed on the upper surface of the digging frame, The aforementioned The rotating conveyor device has a pair of support frames and multiple rows of horizontal rollers. of The support frame is installed on the upper surface of which an endless belt is stretched, and the tip of the support frame is formed so as to be freely folded upward, and both ends of the endless belt are side Department Top of The endless belt Both sides of Packing cover that is always pressed downwards to keep a tight seal and horizontal backing materials are in contact with the undersides of both sides of the endless belt, and the packing cover is composed of a sliding plate that is in contact with the upper surfaces of both sides of the endless belt, a sponge seal that is provided on the upper surface of the sliding plate near the inside of both sides of the endless belt, and a pressing plate that presses the sliding plate from above via the sponge seal, and the upper surfaces of both sides of the endless belt slide on the lower surfaces of the sliding plate, and the lower surfaces of both sides of the endless belt slide on the upper surfaces of the horizontal backing materials. A yam harvester coupled to a tractor, characterized by: , to provide. In order to solve the above-mentioned problems, the present invention also provides a sweet potato harvester connected to a tractor, wherein the sponge seal is made of a rubber-like material having elasticity and restoring force. In addition, in order to solve the above-mentioned problems, the present invention provides a sweet potato harvester that can be connected to a tractor, in which the packing covers are aligned with the upper surfaces of the horizontal backing materials on both sides of the endless belt, holding the sponge seals in a pressed state, and are fixed with lock screws to fasteners provided on the outer surface of the support frame. [Effects of the Invention]

[0006] As described above, the gasket cover is provided so that the cutting edge of the digging blade penetrates the bottom end of the long soil and constantly presses against the endless belt, thereby reducing back pressure and surrounding compressed soil pressure that occur when lifting the cultivated soil blocks over a long period of time and reducing scratches on the long soil.In addition, the tip of the endless belt support frame is foldable, so any soil that does get stuck can be easily swept away in a short time, improving field workability. In addition, a tight-fitting packing cover is provided, constantly pressing down on the top surface of the endless belt, making it possible to work underground for long periods of time. The bottom end of the rotary conveyor is equipped with a relief groove roller with a groove for soil and sand to escape, so even if soil and sand get mixed in, they won't adhere to the roller and ride up. A thin sliding plate is placed on the underside of the packing cover, and a sponge seal is placed on its top surface and fixed with a pressure plate. The elastic repulsive force of the sponge seal constantly presses down on the top surface of the endless belt, preventing soil and sand from getting in, making it possible to work for long periods of time. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a side view showing a working state in which the present invention is implemented. [Figure 2] is a partially omitted plan view [Figure 3] Front view of a yam being excavated [Figure 4] The diagram shows the lifting and lowering of the excavation section. [Figure 5] is a cross-sectional view of the top link support unit [Figure 6] is a perspective view of the top link support unit [Figure 7] The diagram shows the cleaner's drive mechanism. [Figure 8] is an explanatory diagram of the diaphragm drive [Figure 9] is a conventional digging diagram [Figure 10] 1 is a perspective view of the rotating conveyor device. [Figure 11] 1 is an explanatory diagram of the tip rotation part of the rotary conveyor device. [Figure 12] The figure shows the state of folding the tip of the rotating conveyor device. [Figure 13] is an explanatory perspective view of the packing cover [Figure 14] Cross-sectional view showing the packing cover tightly [Figure 15] Illustration of endless belt slack DETAILED DESCRIPTION OF THE INVENTION

[0008] In one embodiment of the present invention, a mounting frame is connected to the rear of a tractor by a three-point link formed by a top link and left and right lower links, a machine frame is connected to the mounting frame, and a support bar is connected to the machine frame to which a digging blade body, consisting of a blade body, a digging plate frame, and a vibration plate, is fixed, and the machine frame is configured to be able to be raised and lowered by the three-point link.The digging blade body is ploughed into the lower end of the grown yam, and it is embraced together with the cultivation soil around the yam in a block shape and raised toward the rear to dig up the yam.In this embodiment of the present invention, a yam harvester that can be connected to a tractor is characterized in that a rotating conveyor device is placed on the upper surface of the digging frame, and this rotating conveyor device is composed of a pair of support frames with multiple rows of horizontal rollers installed on the upper surface of the rollers, and an endless belt is stretched across the upper surface of the rollers, the tips of the support frames are formed to be freely foldable upward, and gasket covers that are constantly pressed against and tightly attached to both ends of the endless belt are provided. The rotary conveyor device is provided at its lower end with a grooved roller having a groove for allowing accumulated soil and sand to escape. A thin sliding plate is disposed on the underside of the packing cover, and a sponge seal is placed on the upper surface of the packing cover and fixed by a pressing plate, so that the upper surface of the endless belt is always pressed. [Example]

[0009] In Figure 1, 1 denotes the rear of a four-wheel riding tractor. The front of the machine frame 3, which supports the digging unit 23, is connected to the rear of the tractor via a three-point linkage 2. 12 denotes a mounting frame, with a top bracket 4 attached to its central top and pivotable in the front-to-rear direction around support shafts 6 fixed to both front sides of the machine frame 3. 7 denotes a top link support unit, which supports the top bracket 4. A well-known top link 46 is connected to the front of the top bracket 4. 8 denotes support bars with a vertical cross section, attached downward on the left and right sides of the machine frame 3. The digging unit 23, tilted rearward, is installed at the lower ends of a pair of support bars 8. The digging blade 9 of the digging unit 23 has a blade 10 at its tip, a rotary conveyor device 49 attached to the top of the digging frame 9-1 in its middle, and a vibrating plate 11 at its rear. The vibrating plate 11 is vibrated slightly by a second hydraulic motor 22. Numeral 19 denotes a cleaner, which removes the upper surface of the cultivated soil block that has been pushed up rearward by the digging blade body 9 to the left and right, causing a long neck to protrude. The cleaner 19 is swung left and right perpendicular to the direction of travel by the first motor 18. Numeral 24 denotes a lift cylinder which uses the support shaft 6 as a fulcrum and, by its extension and contraction, raises and lowers the position of the digging blade body 9 supported by the machine frame 3 relative to the mounting frame 12. In particular, it is used to raise the digging part 23 underground above ground to ensure its height above ground. Numeral 44 denotes a hydraulic arm mounted on the tractor, which raises and lowers the lower link 25. Numeral 45 denotes a lift stay mounted at the rear of the machine frame 3, connected to the top of the mounting frame 12 via the lift cylinder 24. Numeral 49 denotes a rotary conveyor device mounted on the top of the digging frame 9-1, which is installed between the blade 10 forming the digging blade 9 and the vibrating plate 11, so that their surfaces are flush with each other. Numeral 53 denotes a pivoting link. Therefore, when harvesting Chinese yams buried in the soil, the blade 10 is first inserted under the yams and moves forward, forming a soil block and beginning to rise. The endless belt 50 of the rotary conveyor device 49 rotates and rises under the soil pressure of the soil. At this time, the rotation of the endless belt 50 relieves the soil pressure, and the vibration of the vibrating plate 11 loosens the soil block, allowing the raised yams to protrude and be grasped by the operator. FIG. 2 is a partially omitted plan view of the present invention, showing the top link 46 and lower link 25, which form a three-point link. The top link 46 is connected to the top bracket 7 of the mounting frame 12, and the lower links 25 are connected to both front ends of the machine frame 3. The PTO output shaft 5, located at the rear of the tractor, directly drives the hydraulic pump 18, which is transmitted to the hydraulic motor in the digging section via a hose 17. The hydraulic pump 16 drives the first motor 18 and the second motor 22. The first motor 18 is connected to a means for swinging the cleaner 19 left and right. The second hydraulic motor 22 vibrates the vibration plate 11 in the rear half of the digging body 9. The rotary conveyor 49, which forms the digging section 23, is positioned inside the support bar 8 and inclined from front to back. The packing cover 55 prevents soil from entering through the gap between the endless belt 50 of the rotary conveyor 49 and the support frame 52. Reference numeral 20 denotes horizontal shaft-1 and 47 denotes horizontal shaft-2, which are installed horizontally on the machine frame 3. Reference numeral 21 denotes a pipe shaft which is configured to be slidable relative to the horizontal shaft-1 and horizontal shaft-2 installed horizontally.

[0010] Figure 3 shows a front view of the excavation of a long tubercle. The lower ends of longitudinally elongated support bars 8 are fixed to both sides of the digging frame 9-1 that forms the digging blade body 9. The bases of the support bars 8 are fixed to the pipe shaft 21. The pipe shaft 21 is slidably mounted on the horizontal shaft 10. The digging blade body 9 has a blade 10 at its tip, and its rear is tilted upward along with the rotating conveyor device 49. A vibrating plate 11 is connected to the rear end for slight vibration. 55 denotes a packing cover that prevents soil and sand from entering the rotating conveyor device 49. 15 denotes a slide cylinder, one end of which is fixed to the side of the machine frame 3 and the other end is connected to the pipe shaft 21. The digging section 23 is attached to the bottom of this pipe shaft 21 and can slide left and right as desired. 7 denotes a top link support unit, which is mounted on the top of the mounting frame via a shear vault 32. The top bracket 4 is rotatable back and forth and is fixed as desired with a stopper pin 41. One shear vault 32 is arranged vertically. 31 indicates the yam, which rises together with the block-shaped cultivated soil as the digging blade 9 is advanced and the left and right support bars 8 excavate. The digging blade 9 is supported by the support bars 8, and the extension and contraction of the slide cylinder 15 causes the horizontal shafts 1 and 2 to slide and align with the center of the yam furrow. Figure 4 is an explanatory diagram of how the digging unit is raised and lowered. The three-point link 2 at the rear of the tractor raises and lowers the entire digging unit 23 and the machine frame 3. The extension and contraction of the lift cylinder 24 causes the digging unit 23 to further rotate and rise relative to the mounting frame 12, lifting the digging blade 9 to the ground and maintaining a certain ground clearance. If the ground clearance is insufficient depending on the model or manufacturer of the tractor, the top bracket 4 of the top link support unit 7 can be rotated further rearward to move the fulcrum of the top link 46 rearward. It is also within the scope of the present invention to use a hydraulic cylinder positioned perpendicular to the machine frame 3 to slide the digging unit 23 up and down. Figure 5 is an explanatory diagram of the operation of the top link support unit 7, and Figure 6 is a perspective view of the top link support unit 7. The components are as follows: 43 is a base box with an L-shaped side cross section, welded to the top of the mounting frame 12, and rotatably supports the support case 42 via a base shaft 39. 4 is a top bracket, which is rotatably supported by a cross pin 40 on the support case 42. 41 is a stopper pin slidably attached to the support case 42, removed when the top bracket 6 moves forward or backward, and inserted when the forward or backward position is determined to act as a stopper. 32 is a shear vault that secures the bottom plate of the base box 43 to the bottom plate 49 of the support case 42. A single shear vault 32 is positioned vertically on the top of the mounting frame 12, and its breaking strength is set so that it breaks just before the fuselage frame is damaged. 43 is a contact surface -1, which fixes the position of the top bracket 4 when it is tilted forward. In Figure 5, 48 is the impact surface -2, which is the surface that fixes the position when the top bracket 4 is tilted backward. The shear vault 32 is designed in advance to have a strength slightly weaker than the breakage strength of the horizontal axis of the machine frame when an impact force from a rock or the like occurs on the excavation section 23 and the lift cylinder 24. Therefore, when the excavation section 23 collides with a rock buried underground, the shear vault 32 breaks before the machine frame and lift cylinder 24, protecting the machine from damage. In the unlikely event that the shear vault 32 breaks, it can be restored by simply removing the obstructing rock or the like, operating the top link 46, and replacing the shear vault 32. Figure 7 shows an explanatory diagram of the drive of the cleaner 19. The drive sprocket 29 attached to the output shaft of the first hydraulic motor 18 rotates an appropriately reduced-speed driven sprocket 34. The rake 38 of the cleaner 19 is rotatably supported on a boss shaft 36 of a fulcrum shaft 37. The rake 38 is swung back and forth by a connecting rod 35 connected to the driven sprocket 34, and when digging, it sweeps the surface of the floating cultivated soil back and forth, causing its long neck to protrude. Figure 8 shows an explanatory diagram of the drive of the vibrating plate 11, with 11 being the rear of the vibrating plate. 22 denotes a second hydraulic motor, which is connected by hose 17 to the hydraulic pump 18 mentioned above. The second hydraulic motor mentioned above is fixed to the stay 27, and vibrates the vibrating plate 11 up and down via connecting rod 28 as a result of the rotation of eccentric shaft 26. Power is transmitted to the cleaner 19 and vibrating plate 11 via hoses from the hydraulic pump 18 mounted on the tractor side. Figure 9 is an explanatory diagram of a conventional digging technique. The digging blade 9, supported by a support bar 8, comprises a blade 10 at the tip, a digging frame 9-1 in the middle, a digging resin plate 9-2 mounted on the top of the digging frame 9-1, and a vibrating plate 11 at the rear. This diagram shows how, as the tractor advances, the cultivated soil block 56, together with the yam, slides (→B) over the top surface of the digging resin plate 9-2 and rises to the surface. In conventional systems, when the soil is hard or the yam is large, back pressure is generated by the frictional reaction force against the cultivated soil block 56 as the digging resin plate 9-2 slides (B), causing the cultivated soil block 56 to collapse, resulting in the yam crumbling and resulting in scratches or breakage on the surface. Figure 10 shows a perspective view of a novel rotary conveyor. Reference numeral 10 denotes a blade, 49 denotes a rotary conveyor device, and 11 denotes a vibrating plate. The vibrating plate 11 is driven by a second hydraulic motor 22. The rotary conveyor device 49 comprises multiple rows of horizontal rollers 51 arranged on left and right support frames 52, rotatably secured with set screws 54, and an endless belt 50 stretched around the periphery. Reference numeral 55 denotes a gasket cover, which prevents soil from entering the gap between the left and right support frames 49 and the endless belt 50. Therefore, when a yam digger equipped with this device enters the soil and propels it forward, the endless belt of the rotary conveyor device 49 slides upward along with the cultivated soil blocks 56 holding the yam. In other words, frictional force generated on the surface of the endless belt 50 causes the horizontal rollers 51 to rotate, and the cultivated soil blocks float upward as the endless belt 50 slides. Therefore, since no frictional reaction force is generated from the conventional digging resin plate, scratches are less likely to occur on the surface of the Chinese yam. Figure 11 shows a perspective view of the tip rotating section of the rotary conveyor device 49, illustrating the main features of this invention. An appropriate number of horizontal rollers 51 are arranged on support frames 52 located on the left and right, and the tip sections are connected to the left and right via rotary links 53 and are foldable. 55 denotes a packing cover, which removes soil and sand that attempts to enter through the gap between the endless belt 50 and the support frame 52 when the rotary conveyor device 49 is digging underground. The packing cover 55 consists of the sliding plate 61, sponge seal 62, and pressure plate 60 shown in Figure 13, and is secured to the fastening metal 57 with lock screws 63, so that it adheres closely to the surface of the endless belt 50. 57 denotes horizontal backing members that support both the left and right ends of the endless belt 50 and prevent slack. 57 denotes support metal fittings to which the packing cover 50 is secured. Reference numeral 51-1 denotes a clearance groove roller, which is disposed at the lower end of the rotary conveyor device 49. In the unlikely event that soil or sand gets mixed in, the soil or sand accumulated at the lower end escapes from the roller groove of the clearance groove roller 51-1 and does not adhere to the outer periphery of the horizontal roller, so the endless belt does not become tense and lock. Also, if soil or sand gets mixed in and accumulates inside due to use underground for a long period of time, it folds around the pivot link 53 as a fulcrum and is discharged and cleaned. Figure 12 is an explanatory diagram of the folding of the tip of the rotary conveyor device 49. When earth and sand get inside the endless belt 50, the packing cover 55 is removed from the support bracket 57, and then the rotating link 53 is loosened and folded upward. By folding the tip in this way, the endless belt 50 is released, making it easy to remove and clean the earth and sand from inside. Figure 13 is an explanatory perspective view of the packing cover 55. A pair of support frames 52 is formed in a box shape, with multiple rows of horizontal rollers 51 arranged on the left and right sides. The horizontal rollers 51 rotate freely on left and right bearing shafts 59. The bearing shafts 59 are fixed to the support frame 52 with set screws 54. 50 denotes an endless belt, which is suspended around the outer periphery of the multiple rows of horizontal rollers 51. 57 denotes a horizontal backing member, which is provided inside the support frame 52 and contacts both left and right ends of the endless belt 50 to regulate slack and maintain horizontality. 55 denotes a packing cover, 61 is composed of a thin sliding plate, a sponge seal 62, and a pressure plate 60. The sliding plate 61 is always in close contact with the surface of the endless belt 50 and is fixed to a fastener 58 with a lock screw 63 while always in close contact with the surface of the endless belt 50. The sponge seal 62 is made of rubber and has elasticity and resilience, and is always pressed against the top surface of the endless belt. This packing cover 55 is aligned with the upper surfaces of the horizontal backing members 57 located at both ends of the endless belt and holds the sponge seal 62 in an appropriately pressed state, so that the thin sliding plate 61 is always pressed against the upper surface of the endless belt 50 and is in close contact with it. Figure 14 is a cross-sectional view showing the state in which the packing cover 55 is in a tightly fitted state. Reference numeral 57 denotes horizontal backing members located below both ends of the endless belt to keep any slack horizontal. A sliding plate 61 is in tight contact with the upper surface of the endless belt 50, which is held horizontally by the horizontal backing members 57, and a sponge seal 62 is placed on top of this. A pressure plate 60 is then placed on top of this, and a lock screw 63 is fixed to the fastener 63. Therefore, the sliding plate 61 of the packing cover 55 is always pressed against the upper surface of the endless belt 50 to keep it in tight contact. Therefore, the gap between both ends of the endless belt 50 and the support frame 52 is always tightly fitted and covered, preventing the intrusion of soil and sand. Figure 15 shows an explanatory diagram of the slack in the endless belt. The endless belt 50 rotates upward (F) when digging up Chinese yams. That is, as the cultivated soil block moves up and down with the endless belt, the horizontal rollers 51 rotate, reducing friction and back pressure. However, slack (f1) occurs between adjacent rollers at both ends of the endless belt, as shown by the dotted lines, creating gaps. The horizontal backing material 57 regulates this slack in advance and maintains tight contact between the endless belt and the packing cover 55. Therefore, even during long periods of underground harvesting of Chinese yams, the horizontality of both ends of the endless belt 50 is maintained, and the packing cover 55 maintains a pressure-tight seal, preventing the intrusion of soil and sand, enabling a comfortable harvesting operation.

[0008] [Industrial Applicability]

[0011] The long item digging device connected to a tractor according to the present invention is efficient even in the fields of large-scale professional farmers, as it reduces the digging load by installing a rotating conveyor device equipped with the gasket cover of the present invention, while also reducing breakage and scratches on long items.

[0012] [Explanation of symbols]

[0012] 1 Rear of the tractor 2 Three-point hitch 3 Machine frame 4 Top Bracket 5 PTO output shaft 6 spindle 7 Top link support unit 8 support bar 9 Digging blade body 9-1 Excavation Frame 9-2 Excavated resin board 10 Blade 11 Diaphragm 12 Mounting frame 13 Side Stay 14 Horizontal axis - 3 15 Slide cylinder 16 Hydraulic pump 17 Hose 18 First Motor 19 Cleaner 20 Horizontal axis-1 21 Pipe shaft 22 Second motor 23 Digging Section 24 Lift cylinder 25 Lower Link 26 Eccentric shaft 27 Stay 28 Connecting material 29 Drive sprocket 31 Nagaimo 32 Share Vault 33 Rotation support shaft 34 driven sprocket 35 Connecting rod 36 Boss axis 37 Fulcrum Axis 38 Scratching Stick 39 Principles 40 Horizontal pin 41 Stopper pin 42 Support Case 43 Peri-face-1 44 Hydraulic arm 45 Lift Stay 46 Top Links 47 Horizontal axis-2 48 Peri-face-2 49 Rotating conveyor device 50 endless belt 51 Horizontal roller 51-1 Undercut roller 52 Support frame 53 Rotating link 54 Set screw 55 Gasket cover 56 Cultivation soil block 57 Horizontal backing material 58 Fasteners 59 Bearing shaft 60 Retaining plate 61 Sliding plate 62 Sponge Sticker 63 Lock screw

Claims

1. A harvester comprising: a mounting frame connected to the rear of a tractor by a three-point link formed by a top link and left and right lower links; a machine frame connected to the mounting frame; a support bar to which a digging blade body, consisting of a blade body, a digging plate frame, and a vibration plate, is fixed; the machine frame is configured to be able to rise and fall by the three-point link; the digging blade body is ploughed into the lower end of the grown yam, and the yam is held together with the cultivation soil around the yam in a block shape and raised rearward to dig up the yam; A rotary conveyor device is placed on the upper surface of the digging frame, and the rotary conveyor device is configured by installing a plurality of rows of horizontal rollers on a pair of support frames and stretching an endless belt over the upper surface thereof, and the tip of the support frame is formed so as to be freely foldable upward, A packing cover is in contact with the upper surface of each side of the endless belt, and always presses the both side of the endless belt downward to tightly contact the both side of the endless belt. Horizontal support members are placed in contact with the undersides of both sides of the endless belt, The packing cover is composed of a sliding plate that contacts the upper surfaces of both side portions of the endless belt, a sponge seal that is provided on the upper surface of the sliding plate and closer to the inside of both side portions of the endless belt, and a pressing plate that presses the sliding plate from above via the sponge seal, The upper surfaces of both sides of the endless belt slide on the lower surfaces of the sliding plates, The lower surfaces of both sides of the endless belt slide on the upper surfaces of the horizontal backing members. A yam harvester coupled to a tractor, characterized by:

2. A sweet potato harvester connected to the tractor described in claim 1, wherein the sponge seal is rubber-like and has elasticity and resilience.

3. A sweet potato harvester connected to a tractor as described in claim 1 or 2, wherein the packing cover holds the sponge seal in a pressed state by matching with the upper surface of the horizontal support material on both sides of the endless belt, and is fixed to a fastener provided on the outer surface of the support frame with a locking screw.

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