Three-point suspension hooking mechanism for automatic hooking of farm tool

Abstract

The invention discloses a three-point hanging mechanism for automatic hanging of farm tools. The three-point hanging mechanism comprises an upper hanging point module and a lower hanging point module. The upper hanging point module comprises an upper hook and an upper oil cylinder assembly; the lower hanging point module comprises a front beam frame, a rear beam frame, a left lower hook, a right lower hook, a telescopic connecting arm, a lifting assembly, a rotary adjusting device, an angle adjusting motor, a rotary locking device, a left telescopic hanging arm, a right telescopic hanging arm, a left lower oil cylinder, a right lower oil cylinder and a power butt joint device. According to the novel hooking mechanism, the purpose of quick hooking is achieved, the hooking time can be greatly shortened, additional personnel intervention is not needed in the hooking process, hooking can be completed by one driver, labor force can be reduced, and efficiency is improved.

Description

Technical Field

[0001] This invention belongs to the field of tractors, and particularly relates to a three-point suspension attachment mechanism for automatic attachment of agricultural implements. Background Technology

[0002] With the increasing scale and intensification of global agriculture, the demand for efficient attachment devices adapted to high-horsepower tractors has surged to improve operational efficiency. This large-scale operation model has led to higher requirements for the efficiency and convenience of implement attachment in agricultural production, driving the development of automatic attachment devices.

[0003] Traditional implement attachment methods rely heavily on manual operation, which presents numerous problems. For example, the attachment process is time-consuming and dependent on the driver's experience. The operator needs to repeatedly adjust the tractor's position and angle, requiring the tractor to reverse, move forward, adjust the angle, and then reverse again. This repetitive reversing and forward movement is necessary to achieve proper alignment and connection between the implement and the tractor. Furthermore, it lacks multi-directional adjustment capabilities, leading to significant attachment errors. Simultaneously, manual attachment is labor-intensive, especially with large implements, often requiring multiple operators and posing substantial safety risks, making it difficult to meet the demands of modern, efficient agricultural production. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a three-point suspension attachment mechanism for automatically attaching agricultural implements without the need for repeated reversing.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is: a three-point suspension and attachment mechanism for automatic attachment of agricultural implements, comprising: The upper attachment point module includes an upper hook and an upper cylinder assembly. The front end of the upper cylinder assembly is connected to the rear axle of the tractor, and the upper hook is located at the rear end of the upper cylinder assembly. The lower attachment point module includes a front beam frame, a rear beam frame, a left lower hook, and a right lower hook. Telescopic connecting arms are connected to both ends of the front beam frame, and the ends of the telescopic connecting arms are connected to the tractor's rear axle. A lifting assembly is provided between the telescopic connecting arms and the tractor's rear axle. A rotation adjustment device is provided between the front beam frame and the rear beam frame. An angle adjustment motor is installed on the front beam frame, which drives the rear beam frame to rotate via the rotation adjustment device. A rotation locking device is provided on the front beam frame to lock or unlock the rotation adjustment device. A left telescopic attachment arm and a right telescopic attachment arm are laterally slidable at the left and right ends of the rear beam frame, respectively. The left lower hook is located at the lower left end of the left telescopic attachment arm, and a left lower hydraulic cylinder is provided between the left telescopic attachment arm and the rear beam frame. The right lower hook is located at the lower right end of the right telescopic attachment arm, and a right lower hydraulic cylinder is provided between the right telescopic attachment arm and the rear beam frame. A power docking device connected to the tractor's rear output end is installed on the middle of the rear beam frame.

[0006] As a preferred technical solution, the rotation adjustment device includes a front beam connecting frame fixed on the front beam frame and a rear beam connecting frame fixed on the rear beam frame. The rear beam connecting frame is clamped between the front beam connecting frames and the two are connected by a rotating shaft. A driven gear is fixed on the rear beam connecting frame at the axis of the rotating shaft. An active gear is installed at the output end of the angle adjustment motor. The active gear and the driven gear are driven by an intermediate gear. The rotation locking device cooperates with the intermediate gear to lock or unlock.

[0007] As a preferred technical solution, the rotary locking device includes a fixing block fixed to the front beam frame, a locking tongue slidably disposed within the fixing block, a locking tooth disposed at the inner end of the locking tongue, a locking tension spring disposed between the outer end of the locking tongue and the fixing block, a locking tongue rack disposed at the outer end of the locking tongue, an unlocking motor fixed on the front beam frame, an unlocking gear mounted on the output end of the unlocking motor, and the unlocking gear meshing with the locking tongue rack.

[0008] As a preferred technical solution, the power docking device includes a mounting housing fixed to the rear beam frame, a bearing seat slidably mounted inside the mounting housing, a splined bushing rotatably mounted inside the bearing seat, a coupling connected to the front end of the splined bushing, an internal spline machined at the rear end of the splined bushing, and a power docking cylinder provided between the mounting housing and the bearing seat. The power docking cylinder drives the bearing seat to extend and slide, thereby engaging or disengaging the splined bushing from the splined shaft.

[0009] As a preferred technical solution, the lower left hook includes a first hook base, the first hook base having a first hook pin hole and a first hook opening communicating with the first hook pin hole, the first hook base having a first slider guide groove corresponding to the first hook opening, the first hook slider being slidably installed in the first slider guide groove, the opening end of the first hook slider having a first guide arc surface bent toward the first hook pin hole, the tail end of the first hook slider having a first locking tension spring between it and the first hook base, the first hook slider having a first locking positioning member between it and the first hook base, and the first hook slider also having a first electrically controlled unlocking device that overcomes the first locking tension spring; the first electrically controlled unlocking device includes a first unlocking motor mounted on the first hook base, the output end of the first unlocking motor having a first unlocking gear, the surface of the first hook slider away from the first hook pin hole having a first slider rack, and the first unlocking gear and the first slider rack engaging in transmission.

[0010] As a preferred technical solution, the lower right hook includes a second hook base, the second hook base having a second hook pin hole and a second hook opening communicating with the second hook pin hole, the second hook base having a second slider guide groove corresponding to the second hook opening, the second hook slider being slidably installed in the second slider guide groove, the open end of the second hook slider having a second guide arc surface bent toward the second hook pin hole, the tail end of the second hook slider having a second locking tension spring between it and the second hook base, the second hook slider having a second locking positioning member between it and the second hook base, and the second hook slider also having a second electrically controlled unlocking device that overcomes the second locking tension spring; the second electrically controlled unlocking device includes a second unlocking motor mounted on the second hook base, the output end of the second unlocking motor having a second unlocking gear mounted on it, the surface of the second hook slider away from the second hook pin hole having a second slider rack, and the second unlocking gear and the second slider rack engaging in transmission.

[0011] As a preferred technical solution, the upper hook includes a third hook base, the third hook base having a third hook pin hole and a third hook opening communicating with the third hook pin hole, the third hook base having a third slider guide groove corresponding to the third hook opening, a third hook slider slidably mounted in the third slider guide groove, the open end of the third hook slider having a third guide arc surface bent toward the third hook pin hole, a third locking tension spring between the tail end of the third hook slider and the third hook base, a third locking positioning member between the third hook slider and the third hook base, and a third electrically controlled unlocking device on the third hook slider to overcome the third locking tension spring; the third electrically controlled unlocking device includes a third unlocking motor mounted on the third hook base, a third unlocking gear mounted on the output end of the third unlocking motor, a third slider rack on the surface of the third hook slider away from the third hook pin hole, and the third unlocking gear and the third slider rack engaging in transmission.

[0012] As a preferred technical solution, the telescopic connecting arm includes a support arm and an extension arm that is slidably fitted inside the support arm. A positioning hole is provided between the support arm and the extension arm. The rear end of the support arm is fixed to the front beam frame. A connecting fulcrum plate is also provided at the top of the rear end of the support arm. An extension arm connecting hole is provided at the front end of the extension arm.

[0013] As a preferred technical solution, the upper cylinder assembly includes an upper cylinder one and an upper cylinder two. One end of the upper cylinder one is hinged to the rear axle of the tractor, and the upper hook is located at the bottom of the other end of the upper cylinder one. One end of the upper cylinder two is hinged to the rear axle of the tractor, and the other end of the upper cylinder two is hinged to the upper cylinder one.

[0014] As a preferred technical solution, a main controller is provided on the rear beam frame below the power docking device.

[0015] Due to the adoption of the above technical solution, the beneficial effects of the present invention are: the attachment of this application can adjust the position and distance of the three points of the two lower hooks and the upper hook, and can be adapted to three-point suspension implements of various sizes. At the same time, the power docking device can be extended and adapted to implements with power input. In particular, the attachment can rotate the angle, so even if the driver is not skilled in reversing, he can adjust it within a certain range, and no longer requires the operator to repeatedly reverse to find the attachment position and angle as with traditional attachments. Compared with traditional coupling mechanisms, the coupling mechanism of this application only requires one stop before the final stop during the tractor reversing coupling process. During this stop, the tractor remains stationary while adjusting the angle, and then continues reversing. Throughout the entire reversing process, the tractor never moves forward to adjust the angle of the tractor head. In contrast, existing technologies generally require repeated adjustments to the tractor head angle to accommodate the implement's angle. As a result, the tractor repeatedly moves forward and backward until the attachment is parallel to the implement. This adjustment method is prone to errors, inefficient, and time-consuming. Currently, existing technologies can only use this method for adjustment. However, this application innovatively provides a new coupling mechanism to achieve rapid coupling, greatly reducing coupling time. The coupling process does not require additional personnel intervention; the driver alone can complete the coupling, reducing labor and improving efficiency. Attached Figure Description

[0016] The following figures are intended only to illustrate and explain the present invention and do not limit the scope of the invention. Wherein: Figure 1 This is a side view of the hanging fixture according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of the hanging fixture according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the hanging point module in an embodiment of the present invention; Figure 4 This is a structural schematic diagram of the hanging point module from another angle in an embodiment of the present invention; Figure 5 This is a top view of the initial state of the hanging point module in an embodiment of the present invention; Figure 6 This is a top view of the hanging point module after angle adjustment in an embodiment of the present invention; Figure 7 This is a schematic diagram of the structure of the rotary locking device according to an embodiment of the present invention; Figure 8 This is a top view of the power docking device according to an embodiment of the present invention; Figure 9 This is a schematic diagram of the power docking device according to an embodiment of the present invention; Figure 10 This is a structural cross-sectional view of the power docking device according to an embodiment of the present invention; Figure 11 This is a schematic diagram of the structure of the lower left hook in an embodiment of the present invention; Figure 12 This is a structural cross-sectional view of the lower left hook in an embodiment of the present invention; Figure 13 This is a schematic diagram of the structure of the agricultural implement according to an embodiment of the present invention; Figure 14 This is a block diagram of the automatic attachment method according to an embodiment of the present invention; Figure 15 This is a simplified diagram of the attachment state in an embodiment of the present invention; Figure 16 This is a diagram showing the state of the attachment before it is connected to the agricultural implement in an embodiment of the present invention; Figure 17 This is a diagram showing the state of the hook descending below the lower hanging point in an embodiment of the present invention; Figure 18 This is a state diagram of the hook moving to directly below the hanging point in an embodiment of the present invention; Figure 19 This is a state diagram of the hook and the hanging point after they are connected according to an embodiment of the present invention; Figure 20 This is a state diagram of the upper hook and upper hanging point after they are connected in an embodiment of the present invention; Figure 21 This is a state diagram of the power docking device after it has been attached according to an embodiment of the present invention; In the diagram: A - Hanger; 10 - Upper hanging point module; 11 - Upper hook; 12 - Upper cylinder assembly; 12a - Upper cylinder one; 12b - Upper cylinder two; 20 - Lower hanging point module; 21-Front beam frame; 22-Rear beam frame; 23-Lower left hook; 23a-First hook seat; 23b-First hook pin hole; 23c-First hook slider; 23d-First locking spring; 23e-First unlocking motor; 23f-First unlocking gear; 23g-First slider rack; 24-Lower right hook; 25-Telescopic connecting arm; 25a-Support arm; 25b-Extension arm; 25c-Connecting fulcrum plate; 25d-Extension arm connecting hole; 26-Lifting assembly; 26a-Adjusting rod; 26b-Lifting arm; 26c-Lifting hydraulic cylinder; 27-Rotation adjustment device; 27a-Front beam connecting frame; 27b-Rear beam connecting frame; 27c-Passive gear; 27d- 27e-Intermediate gear; 28-Angle adjustment motor; 29-Rotary locking device; 29a-Fixing block; 29b-Locking tongue; 29c-Locking tooth; 29d-Locking tension spring; 29e-Unlocking motor; 29f-Unlocking gear; 210-Left telescopic arm; 211-Right telescopic arm; 212-Left lower cylinder; 213-Right lower cylinder; 214-Power docking device; 214a-Mounting housing; 214b-Bearing seat; 214c-Guide shaft; 214d-Splined bushing; 214e-Coupling; 214f-Telescopic cylinder; 214g-Extension plate; 214h-Power docking cylinder; 30-Main controller; 40-Tractor rear axle; B - Agricultural implement; 50 - Upper mounting point; 60 - Lower left mounting point; 70 - Lower right mounting point; 80 - Splined shaft; 90 - Secondary controller. Detailed Implementation

[0017] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the following detailed description, only certain exemplary embodiments of the invention are described by way of illustration. Undoubtedly, those skilled in the art will recognize that various modifications can be made to the described embodiments without departing from the spirit and scope of the invention. Therefore, the drawings and description are illustrative in nature and not intended to limit the scope of the claims.

[0018] The attachment of tractor implements involves connecting implement A to implement B via suspension and power. Implement B is typically placed on the ground, while implement A is attached to the rear of the tractor. The tractor reverses, causing implement A to engage with implement B. For large-scale agricultural production, implement A needs to be compatible with various sizes of implement B, thus requiring a design that adapts both implement A and implement B.

[0019] like Figures 1 to 13As shown, a three-point suspension mechanism for automatic attachment of agricultural implements, namely attachment A, includes an upper attachment point module 10, a lower attachment point module 20, and a main controller 30. The upper attachment point module 10 and the lower attachment point module 20 are independent of each other and are respectively installed on the rear axle 40 of the tractor. The upper attachment point module 10 and the lower attachment point module 20 cooperate to form a three-point suspension. The main controller 30 is located on the lower attachment point module 20 and is used to acquire and control the attitude and position of the upper attachment point module 10 and the lower attachment point module 20. It is used in conjunction with the controller inside the tractor and with the secondary controller inside the implement B. In this embodiment, combined with Figure 1 and Figure 2 The tractor rear axle 40 refers to the gearbox housing located at the rear of the tractor.

[0020] See Figure 1 and Figure 2 The upper attachment point module 10 includes an upper hook 11 and an upper cylinder assembly 12. The upper cylinder assembly 12 is used to adjust the position of the upper hook 11. The front end of the upper cylinder assembly 12 is connected to the rear axle 40 of the tractor, and the upper hook 11 is located at the rear end of the upper cylinder assembly 12.

[0021] The upper cylinder assembly 12 includes an upper cylinder 12a and an upper cylinder 12b. The front end of the upper cylinder 12a is hinged to the rear axle 40 of the tractor, and the upper hook 11 is located at the rear end of the upper cylinder 12a. The upper cylinder 12b is located above the upper cylinder 12a, with its front end hinged to the rear axle 40 of the tractor and its rear end hinged to the upper cylinder 12a. The upper cylinder 12a is used to control the extension and retraction, and the upper cylinder 12b is used to control the tilt angle of the upper cylinder 12a. The upper cylinder 12a and the upper cylinder 12b work together to change the position of the upper hook 11 to adapt to the upper attachment point of the implement B.

[0022] The upper hook 11 is equipped with an upper positioner, which is used to collect the three-dimensional coordinate information of the position of the upper hook 11 in real time and transmit the three-dimensional coordinate information to the main controller 30; both the upper cylinder 12a and the upper cylinder 12b are equipped with displacement sensors, which can monitor the extension distance of the cylinder in real time and transmit the monitored data to the main controller 30.

[0023] The lower mounting point module 20 includes a front beam frame 21, a rear beam frame 22, a left lower hook 23, and a right lower hook 24. Telescopic connecting arms 25 are connected to the left and right ends of the front beam frame 21, respectively. The rear ends of the two telescopic connecting arms 25 are connected to the left and right ends of the front beam frame 21, respectively. The front ends of the telescopic connecting arms 25 are connected to the tractor rear axle 40. A lifting assembly 26 is provided between the telescopic connecting arms 25 and the tractor rear axle 40. A rotation adjustment device 27 is provided between the front beam frame 21 and the rear beam frame 22. An angle adjustment motor 28 is provided on the front beam frame 21. The angle adjustment motor 28 drives the rear beam frame 22 to rotate through the rotation adjustment device 27. A rotation locking device 29 is provided on the front beam frame 21 to lock or unlock the rotation adjustment device 27. A left telescopic hook arm 210 and a right telescopic hook arm 211 are slidably provided laterally on the left and right ends of the rear beam frame 22, respectively. The left lower hook 23 is located at the... A lower left hydraulic cylinder 212 is provided at the lower left end of the left telescopic arm 210, between the left telescopic arm 210 and the rear beam frame 22. The two ends of the lower left hydraulic cylinder 212 are respectively connected to the left telescopic arm 210 and the rear beam frame 22, and are used to drive the left telescopic arm 210 to move the lower left hook 23 in the left-right direction. A lower right hook 24 is located at the lower right end of the right telescopic arm 211. The right telescopic arm 211 and the rear beam frame 22... A lower right hydraulic cylinder 213 is provided between the frames 22. The two ends of the lower right hydraulic cylinder 213 are respectively connected to the right telescopic hook arm 211 and the rear beam frame 22, and are used to drive the right telescopic hook arm 211 to move the lower right hook 24 in the left and right direction. A power docking device 214 connected to the rear output end of the tractor is installed on the middle part of the rear beam frame 22. The power docking device 214 is a component used to connect the rear output end of the tractor to the power input end of the implement B.

[0024] The main controller 30 is mounted on the rear beam frame 22. The lower left cylinder 212 and the lower right cylinder 213 are equipped with displacement sensors, which can monitor the extension distance of the cylinders in real time and transmit the monitored data to the main controller 30.

[0025] See Figure 3 and Figure 4 The telescopic connecting arm 25 includes a support arm 25a and an extension arm 25b slidably fitted inside the support arm 25a. A positioning hole is provided between the support arm 25a and the extension arm 25b, and at least two positioning holes are connected by bolts or pins. The rear end of the support arm 25a is fixed to the front beam frame 21 by U-bolts. A connecting fulcrum plate 25c is also provided at the top of the rear end of the support arm 25a. The front end of the extension arm 25b is provided with an extension arm 25b connecting hole, and is hinged to the tractor rear axle 40 through the extension arm connecting hole 25d.

[0026] The lifting assembly 26 can drive the telescopic connecting arm 25 to swing up and down, thereby adjusting the height position of the lower mounting point module 20. The lifting assembly 26 includes an adjusting rod 26a, a lifting arm 26b, and a lifting hydraulic cylinder 26c. The bottom end of the adjusting rod 26a is hinged to the connecting fulcrum plate 25c, the top end of the adjusting rod 26a is hinged to the rear end of the lifting arm 26b, the front end of the lifting arm 26b is hinged to the tractor rear axle 40, the top end of the lifting hydraulic cylinder 26c is hinged to the middle of the lifting arm 26b, and the bottom end of the lifting hydraulic cylinder 26c is hinged to the tractor rear axle 40. When the lifting hydraulic cylinder 26c extends, the lifting arm 26b swings upward, and the telescopic connecting arm 25 is pulled upward by the adjusting rod 26a, thereby increasing the height of the lower left hook 23, the lower right hook 24, and the power docking device 214. When the lifting hydraulic cylinder 26c retracts, the lifting arm 26b swings downward, and the telescopic connecting arm 25 is pushed downward by the adjusting rod 26a, thereby decreasing the height of the lower left hook 23, the lower right hook 24, and the power docking device 214.

[0027] See Figures 3 to 5 The rotation adjustment device 27 includes a front beam connecting frame 27a fixed to the front beam frame 21 and two rear beam connecting frames 27b fixed to the rear beam frame 22. The two rear beam connecting frames 27b are sandwiched between the front beam connecting frame 27a and connected by a rotating shaft. A driven gear 27c is fixed on the rear beam connecting frame 27b at the axis of the rotating shaft. The body of the angle adjustment motor 28 is fixed to the front beam frame 21. A driving gear 27d is installed at the output end of the angle adjustment motor 28. The driving gear 27d and the driven gear 27c are driven by an intermediate gear 27e. The intermediate gear 27e is rotatably connected to the front beam frame 21. The rotation locking device 29 cooperates with the intermediate gear 27e to lock or unlock. When the rotation locking device 29 is in the locked state, the intermediate gear 27e is locked, and the angle adjustment motor 28 cannot make the intermediate gear 27e rotate. Therefore, the rear beam frame 22 is fixed and no longer rotates relative to the front beam frame 21. When the rotation locking device 29 is in the unlocked state, the intermediate gear 27e is released. The angle adjustment motor 28, through the driving gear 27d, drives the intermediate gear 27e to rotate, thereby causing the rear beam connecting frame 27b to rotate around the pivot through the driven gear 27c. This causes the rear beam frame 22 to rotate relative to the front beam frame 21. See the diagram for the rotated state. Figure 6 .

[0028] See Figure 7The rotary locking device 29 includes a fixing block 29a fixed to the front beam frame 21. A locking tongue 29b is slidably provided in the fixing block 29a. The inner end of the locking tongue 29b is provided with a locking tooth 29c. The locking tooth 29c is engaged with the tooth profile of the intermediate gear 27e. A locking tension spring 29d is provided between the outer end of the locking tongue 29b and the fixing block 29a. One end of the locking tension spring 29d is connected to the locking tongue 29b, and the other end is connected to the fixing block 29a. The outer end of the locking tongue 29b is also provided with a locking tongue 29b rack. An unlocking motor 29e is fixed on the front beam frame 21. An unlocking gear 29f is installed at the output end of the unlocking motor 29e. The unlocking gear 29f meshes with the locking tongue 29b rack. The locking spring 29d pulls the locking tongue 29b towards the intermediate gear 27e, causing the locking tooth 29c to engage with the intermediate gear 27e, thereby restricting the rotation of the intermediate gear 27e and achieving the locking purpose. See the image for the locked state. Figure 7 When unlocking is required, the unlocking motor 29e is energized, driving the unlocking gear 29f to rotate. The locking tongue 29b moves away from the intermediate gear 27e via the rack and pinion, separating the locking tooth 29c from the intermediate gear 27e, thus achieving the purpose of unlocking.

[0029] See Figures 8 to 10 The power docking device 214 includes a mounting housing 214a fixed to the rear beam frame 22. The mounting housing 214a serves as the mounting base. A bearing seat 214b is slidably mounted inside the mounting housing 214a. In this embodiment, the mounting housing 214a has four elongated guide holes. Guide shafts 214c are slidably mounted in each of the guide holes. The front portion of the guide shaft 214c slides within the guide holes, and the rear end of the guide shaft 214c is threaded and fixedly connected to the bearing seat 214b. Under the guidance of the guide shaft 214c, the bearing housing 214b can slide axially within the mounting housing 214a; a splined bushing 214d is installed in the bearing housing 214b via a bearing, the front end of the splined bushing 214d is connected to the coupling 214e via a locking screw, and the coupling 214e is connected to the rear output shaft of the tractor via a telescopic cylinder 214f; the rear end of the splined bushing 214d is machined with an internal spline and has a chamfer, and the implement B is provided with a splined shaft that mates with the splined bushing 214d.

[0030] In this embodiment, two bearings are disposed within the bearing housing 214b, with a bearing retaining sleeve between them. The bearing retaining sleeve includes an inner retaining sleeve and an outer retaining sleeve. The inner retaining sleeve rests on the inner ring of the bearing, and the outer retaining sleeve rests on the outer ring of the bearing. A sealing groove is provided at the rear end of the bearing housing 214b, and a sealing ring is disposed within the sealing groove for dust prevention. The end cap of the bearing housing 214b has a stop that rests on the outer ring of the bearing to prevent bearing slippage. The splined bushing 214d is a stepped shaft, which has a retaining step to limit the bearing. A bearing lock nut is installed at the retaining step to lock the bearing.

[0031] An extension plate 214g, extending axially along the splined bushing 214d, is fixedly mounted on the mounting housing 214a. A power docking cylinder 214h is mounted on the extension plate 214g. The power docking cylinder 214h drives the bearing seat 214b to extend and slide. The piston rod end of the cylinder is fixedly connected to the bearing seat 214b. The power docking cylinder 214h drives the bearing seat 214b to extend and slide, thereby allowing the splined bushing 214d to engage or disengage with the splined shaft of the implement B. The power docking cylinder 214h is equipped with a displacement sensor, which can monitor the extension distance of the cylinder in real time and transmit the monitored data to the main controller 30.

[0032] After the front and rear coupling parts are coarsely positioned, the axes of the spline shaft and the spline sleeve 214d are largely aligned. In this state, the movement of the power docking cylinder 214h is controlled by a hydraulic valve. When the power docking cylinder 214h extends, it pushes the bearing seat 214b to move, thereby indirectly driving the spline sleeve 214d to extend. Under the chamfering guide, the spline shaft smoothly inserts into the spline sleeve 214d. When the power docking cylinder 214h moves to its limit position, the docking is completed, and the cylinder self-locks to prevent the spline sleeve 214d from falling off during movement. In this way, the cooperation between the spline shaft and the spline sleeve 214d enables torque transmission. The power docking is fully automatic, requiring no manual intervention, which can significantly improve connection efficiency and ensure stable and reliable torque transmission. After docking, the axis of the spline shaft coincides with that of the spline bushing 214d. At this time, only the side of the spline is in contact with the spline shaft and the spline bushing 214d. When the spline shaft rotates, it will hardly be subjected to any radial force. Without the action of radial force, the device will not vibrate or rub, thereby extending the service life of the spline.

[0033] The lower left hook 23, lower right hook 24, and upper hook 11 have basically the same structure, only differing in their installation position and direction. The lower left hook 23 and lower right hook 24 have upward-facing openings, and are hooked from bottom to top. The upper hook 11 has downward-facing openings, and is hooked from top to bottom. Since their structure and principle are essentially the same, only the left hook will be described here in conjunction with the attached diagram.

[0034] See Figure 11 and Figure 12 The lower left hook 23 includes a first hook seat 23a, which is fixed to the left end of the left telescopic hook arm 210. The first hook seat 23a has a first hook pin hole 23b and a first hook opening communicating with the first hook pin hole 23b. The first hook opening faces upwards. A first slider guide groove is provided in the first hook seat 23a corresponding to the first hook opening. A first hook slider 23c is slidably installed in the first slider guide groove. The open end of the first hook slider 23c has a first guide arc surface curved towards the first hook pin hole 23b. The tail end of the first hook slider 23c is connected to the first hook seat. A first locking spring 23d is provided between 23a and the first hook seat 23a. A first locking positioning member is provided between the first hook slider 23c and the first hook seat 23a. The first hook slider 23c is also provided with a first electrically controlled unlocking device that overcomes the first locking spring 23d. The first electrically controlled unlocking device includes a first unlocking motor 23e provided on the first hook seat 23a. A first unlocking gear 23f is installed at the output end of the first unlocking motor 23e. A first slider rack 23g is provided on the side surface of the first hook slider 23c away from the first hook pin hole 23b. The first unlocking gear 23f and the first slider rack 23g cooperate for transmission. When the lower left hook 23 moves upward towards the pin at the lower hanging point, the first hooking slider 23c contacts the pin. As the lower left hook 23 continues to move upward, the pin pushes the first hooking slider 23c downward, overcoming the first locking spring 23d, causing the first hooking slider 23c to slide downward relative to the first hook seat 23a, opening the first hooking opening. As the lower left hook 23 continues to move upward, the pin enters the first hooking pin hole 23b along the first guide arc surface. The first hooking slider 23c is no longer pressed by the pin, and therefore resets and locks under the action of the first locking spring 23d. When unlocking is required, the first unlocking motor 23e is energized, driving the first unlocking gear 23f to rotate. The first slider rack 23g overcomes the elastic force of the first locking spring 23d, causing the first hooking slider 23c to open downward. Then, the lower left hook 23 is moved so that the pin leaves the first hooking opening.

[0035] The lower right hook 24 includes a second hook base, which has a second hook pin hole and a second hook opening communicating with the second hook pin hole. A second slider guide groove is provided in the second hook base corresponding to the second hook opening. A second hook slider is slidably installed in the second slider guide groove. The open end of the second hook slider has a second guide arc surface curved towards the second hook pin hole. A second locking spring is provided between the tail end of the second hook slider and the second hook base. A second locking positioning element is provided between the second hook slider and the second hook base. The second hook slider also has a second electrically controlled unlocking device that overcomes the second locking spring. The second electrically controlled unlocking device includes a second unlocking motor mounted on the second hook base. A second unlocking gear is installed at the output end of the second unlocking motor. A second slider rack is provided on the surface of the second hook slider away from the second hook pin hole. The second unlocking gear and the second slider rack cooperate for transmission. The working principle of the lower right hook 24 is the same as that of the lower left hook 23, and will not be described again here.

[0036] The upper hook 11 includes a third hook base, which has a third hook pin hole and a third hook opening communicating with the third hook pin hole. A third slider guide groove is provided in the third hook base corresponding to the third hook opening. A third hook slider is slidably installed in the third slider guide groove. The open end of the third hook slider has a third guide arc surface curved towards the third hook pin hole. A third locking spring is provided between the tail end of the third hook slider and the third hook base. A third locking positioning element is provided between the third hook slider and the third hook base. The third hook slider also has a third electrically controlled unlocking device that overcomes the third locking spring. The third electrically controlled unlocking device includes a third unlocking motor mounted on the third hook base. A third unlocking gear is installed at the output end of the third unlocking motor. A third slider rack is provided on the surface of the third hook slider away from the third hook pin hole. The third unlocking gear and the third slider rack cooperate for transmission. The working principle of the upper hook 11 is the same as that of the lower left hook 23, and will not be described again here.

[0037] See Figure 13To accommodate the aforementioned attachment, implement B has three attachment points arranged in an isosceles triangle: upper attachment point 50, lower left attachment point 60, and lower right attachment point 70. A spline shaft 80 is located in the middle of these three attachment points. A secondary controller 90 is also installed on implement B to record basic information such as its name, weight, position, interface orientation, interface position, ground clearance, and input shaft information. By installing locators at each of the three attachment points, the three-dimensional coordinates of each point can be detected and transmitted to the secondary controller 90 to obtain the relative distances between the attachment points. These three-dimensional coordinates and relative distances are then used as the interface position information. Alternatively, the relative distances between interfaces can be pre-stored in the secondary controller 90, and radar can be used at the rear end of the attachment A to obtain the relative positions of each interface and hook, thus providing the three-dimensional coordinates of each interface.

[0038] See Figure 14 A three-point suspension method for automatic attachment of agricultural implement B includes the following steps: Preparation stage before attachment: Connect the above-mentioned attachment A to the rear axle 40 of the tractor and connect attachment A to the power end of the tractor. Several different types or models of agricultural implements B are placed on the ground waiting to be attached.

[0039] S1. Reversing adjustment based on the position of implement B: After the driver selects the implement B to be attached in the cab, the main controller 30 of the tractor's rear attachment A will communicate with the secondary controller 90 of the selected implement B. The main controller 30 obtains the position information and interface orientation information of implement B. The main controller 30 locates the position of implement B based on the position information and determines the orientation of the implement B's interface based on the interface orientation information. The position and direction of the implement are displayed on the cab display screen. The driver then controls the tractor to reverse towards the implement interface. (See the initial state for details.) Figure 16 During this process, the tractor reverses manually based on the obtained data. Since the subsequent engagement can be completed well using special methods, the accuracy requirement for the tractor reversing is not high, and it can be considered a coarse positioning.

[0040] S2. Adjusting the lower hook according to interface information: During reversing, the main controller 30 acquires the interface position information and ground clearance information of implement B. Based on the interface position information, the main controller 30 obtains the distance between the lower left hook point 60 and the lower right hook point 70 of implement B, defining it as L. Simultaneously, based on the left and right hook positioners, it obtains the distance between the lower left hook 23 and the lower right hook 24 of the attachment A, defining it as L1. Then, it determines whether L1 equals L. When L1 ≠ L, it controls the lower left cylinder 212 and the lower right cylinder 213 to synchronously extend and retract in the left and right directions until L1 = L. During the cylinder extension and retraction, the upper cylinder assembly 12 drives the upper hook 11 to swing upwards away from implement B to avoid affecting the engagement of the lower left hook 23 and the lower right hook 24. (See [link]). Figure 15 (a) The front and back changes of the left and right hooks; The main controller 30 then obtains the heights of the lower left hook point 60 and the lower right hook point 70 of implement B relative to the ground based on the ground clearance information, and defines them as H. Simultaneously, it obtains the heights of the lower left hook 23 and the lower right hook 24 of implement A relative to the ground based on the left and right hook positioners, and defines them as H1. Then, it compares H1 with H. When H1 + 10cm ≥ H, it controls the lifting component 26 to move, causing the lower left hook 23 and the lower right hook 24 to descend simultaneously until H1 + 10cm < H, at which point it stops. The state after height adjustment is shown in [reference needed]. Figure 17 ; During the reversing process, the main controller 30 and the secondary controller 90 communicate in real time to determine the relative positions of the two lower hooks of attachment A and the two lower attachment points of implement B. When one of the lower hooks of attachment A moves to the area below the two lower attachment points of implement B, the reversing stops, completing the coarse positioning of the tractor. During the coarse positioning process, the tractor remains in a reversing state, adjusting the width between the two lower hooks and the height of the two lower hooks simultaneously. This process requires only one reversing and stopping, without the need for repeated adjustments.

[0041] S3. Determine if parallel and adjust angle: In the first parking state, before angle adjustment, the rear beam frame 22 is initially parallel to the front beam frame 21. The main controller 30 then obtains the line connecting the two lower hook points based on the interface position information of implement B, defining it as AB. Based on the left and right hook positioners, it obtains the line connecting the two lower hooks, positioning it as AB1. Then, it determines if AB and AB1 are parallel. If AB and AB1 are not parallel, the main controller 30 calculates the deviation angle and direction between AB and AB1, converting the deviation angle into the number of rotations of the angle adjustment motor 28. Simultaneously, it controls the rotation locking device 29 to be energized and unlocked. Then, the angle adjustment motor 28 rotates quantitatively according to the number of rotations and direction, driving the rear beam frame 22 and the two lower hooks installed on the rear beam frame 22 to rotate as a whole until AB and AB1 are parallel, thus completing the angle adjustment. See [link to relevant documentation]. Figure 15 (b) Changes in the left and right hooks. During angle adjustment, the tractor remains stationary, making it more accurate to determine the positions of the hooks and attachment points. Only the rear beam 22 needs adjustment to align the two lower hooks with the two lower attachment points. In this embodiment, when the tractor reverses towards implement B, the tractor's front may face either the left front or the right front of implement B. When implement B faces the left front, the rear beam 22 needs to be rotated clockwise; when implement B faces the right front, the rear beam 22 needs to be rotated counter-clockwise. Therefore, the rotation direction of the rear beam 22 is first determined, and then adjusted clockwise or counter-clockwise based on the deviation angle.

[0042] S4. Continue reversing, adjusting and engaging the lower hooks: The tractor continues to reverse, moving the two lower hooks of attachment A towards implement B. Reversing stops when they are below the two lower hook points of implement B. The main controller 30 calculates the distance between the lower left hook 23 and the lower left hook point 60 in the left-right direction based on their positions. It also calculates the distance between the lower right hook 24 and the lower right hook point 70 in the left-right direction based on their positions. Based on these distances, it controls the lower left cylinder 212 and the lower right cylinder 213 to move simultaneously, one extending and the other retracting, with equal extension and retraction amounts. When the lower left hook 23 is directly below the lower left hook point 60 and the lower right hook 24 is directly below the lower right hook point 70, both cylinders stop. (See below) Figure 15 (c) shows the forward and backward changes of the left and right hooks, and the adjusted state is shown in the figure. Figure 17Subsequently, the main controller 30 controls the lifting assembly 26 to simultaneously lift the lower left hook 23 and the lower right hook 24. During the lifting process, the pins at the lower left hook point 60 and the lower right hook point 70 of implement B will press the lower left hook 23 and the lower right hook 24 to open, engage, and then lock, completing the automatic engagement of the lower left hook point 60 with the lower left hook 23 and the lower right hook point 70 with the lower right hook 24. The state after engagement is shown in [reference needed]. Figure 19 During this stage, the tractor reverses and stops again to facilitate the engagement of the lower coupling point.

[0043] S5. Adjustment and engagement of upper hook 11: Based on the relative positions of the upper hook point 50 of implement B and the upper hook 11 of implement A, the main controller 30 controls the upper cylinder assembly to move, causing the upper hook 11 to move from top to bottom towards the upper hook point 50. The pin at the upper hook point 50 will press the upper hook 11 to open, engage, and then lock, completing the automatic engagement of the upper hook point 50 and the upper hook 11. See the attached diagram for the engagement status. Figure 20 During this phase, the tractor remains stationary.

[0044] S6. Restore initial state, shaft power adjustment and attachment: After all three attachment points are engaged, the main controller 30 controls the lifting assembly 26 and the upper hydraulic cylinder assembly to move, lifting implement B off the ground; then, it controls the angle adjustment motor 28 to rotate in the opposite direction according to the number of rotations, driving the rear beam frame 22 and implement B to rotate in the opposite direction, restoring the initial state. See below. Figure 15 (d) The left and right hooks change back and forth, and then the rotating locking device 29 is de-energized and locked. During this stage, the tractor remains stationary, but the angle adjustment motor 28 can drive the entire implement B to change angle to adapt to the position of the tractor. During the rotation of implement B, the upper cylinder assembly 12, the lower left cylinder 212, and the lower right cylinder 213 move synchronously to make adaptive adjustments. Finally, the extension of the lower left cylinder 212 and the lower right cylinder 213 is the same, and the plane containing the upper hook 11, the lower left hook 23, and the lower right hook 24 stops when it is perpendicular to the ground. Then, the main controller 30 controls the power docking cylinder 214h to extend and drive the splined bushing 214d to move toward implement B. The splined bushing 214d is inserted into the splined shaft 80 of implement B and locked. The tractor's power is transmitted to implement B through the coupling 214e, the splined bushing 214d, and the splined shaft 80, completing the power docking between implement A and implement B. See the state after power docking. Figure 21 .

[0045] S7. Hook-and-unhook separation: The main controller 30 first controls the power docking cylinder 214h to retract, disconnecting the spline bushing 214d from the spline shaft 80. Then, it controls the lifting assembly 26 and the upper cylinder assembly 12 to place implement B on the ground. Next, it controls the upper hook 11, lower left hook 23, and lower right hook 24 to unlock electrically. Then, the upper cylinder assembly 12 moves the upper hook 11 upward and disengages it from the upper attachment point 50. Then, the lifting assembly 26 moves the lower left hook 23 and lower right hook 24 downward and disengages them from the lower left attachment point 60 and lower right attachment point 70. The tractor moves forward, achieving complete separation of implement B from attachment A.

[0046] The attachment of this application can adjust the position and distance of the three points of the two lower hooks and the upper hook, and can be adapted to a variety of three-point suspension implements of various sizes. At the same time, the power docking device can be extended and retracted to adapt to implements with power input. Most importantly, the attachment can rotate, so even if the driver is not skilled at reversing, he can adjust it within a certain range, no longer requiring the operator to repeatedly reverse to find the attachment position and angle as with traditional attachments. During the reversing process, the tractor only needs to stop twice. The first stop involves two key actions: angle adjustment and hook translation. First, the angle adjustment directly changes the direction of the attachment to adapt to the angle of the implement. Then, the left and right lower hooks are translated simultaneously to change the position of the hooks relative to the two lower attachment points in the left-right direction. This achieves the effect of the two lower hooks being parallel to the two lower attachment points and consistent in the left-right direction. During the adjustment process, the tractor remains stationary, achieving an effect where the tractor is stationary but perfectly matched with the lower attachment points. The second stop is the final stop, where the attachment points are engaged and the power is connected. Therefore, the second stop is the same as the final stop in the traditional attachment method. The first stop is a coarse positioning of the tractor, which does not require very strict direction and position of the tractor. Based on this coarse positioning, angle adjustment and hook translation are then performed to achieve precise positioning. Therefore, the requirements for tractor reversing are reduced, and the requirements for the driver are also lower, greatly reducing the difficulty of attachment. Compared with traditional methods, the tractor's reversing coupling method in this application only stops once in the middle before the final stop, and the angle is adjusted while the tractor remains stationary during the middle stop. After the angle adjustment, the tractor continues to reverse. Throughout the entire reversing process, the tractor never moves forward to adjust the angle of the front of the tractor. In contrast, in existing technologies, to adapt to the angle of the implement, the angle of the tractor's front of the tractor generally needs to be repeatedly adjusted. Therefore, the tractor will repeatedly move forward and reverse until the attachment is parallel to the implement. This adjustment method has large errors, low efficiency, and is time-consuming and labor-intensive. However, in current technologies, this is the only way to adjust. This application innovatively provides a new structural combination method to achieve the purpose of rapid coupling, which can greatly reduce coupling time. The coupling process does not require additional personnel intervention, and the driver can complete the coupling alone, which can reduce labor and improve efficiency.

[0047] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. An automatic hitching three-point linkage for agricultural implements, characterized in that The utility model relates to a tractor hitching device, which comprises an upper hitching point module and a lower hitching point module. The upper hitching point module comprises an upper hook and an upper oil cylinder assembly, the front end of the upper oil cylinder assembly is connected to the rear axle of a tractor, and the upper hook is arranged at the rear end of the upper oil cylinder assembly. The lower hitching point module comprises a front beam frame, a rear beam frame, a left lower hook and a right lower hook, the left and right ends of the front beam frame are respectively connected with telescopic connecting arms, the telescopic connecting arms are connected to the rear axle of the tractor, and a lifting assembly is arranged between the telescopic connecting arms and the rear axle of the tractor; a rotary adjusting device is arranged between the front beam frame and the rear beam frame, an angle adjusting motor is arranged on the front beam frame, the angle adjusting motor drives the rear beam frame to rotate through the rotary adjusting device, a rotary locking device is arranged on the front beam frame to lock or unlock the rotary adjusting device; a left telescopic hanging arm and a right telescopic hanging arm are respectively arranged on the left end and the right end of the rear beam frame in a sliding manner, the left lower hook is arranged at the lower part of the left end of the left telescopic hanging arm, a left lower oil cylinder is arranged between the left telescopic hanging arm and the rear beam frame, the right lower hook is arranged at the lower part of the right end of the right telescopic hanging arm, a right lower oil cylinder is arranged between the right telescopic hanging arm and the rear beam frame, and a power docking device connected with the rear output end of the tractor is arranged on the middle part of the rear beam frame.

2. A three-point linkage of an agricultural implement for automatic hitching, according to claim 1, characterized in that: The rotary adjusting device comprises a front beam connecting frame fixed to the front beam frame and a rear beam connecting frame fixed to the rear beam frame, the rear beam connecting frame is clamped between the front beam connecting frames and connected through a rotating shaft, a driven gear is fixed on the rear beam connecting frame at the axis of the rotating shaft, a driving gear is mounted at the output end of the angle adjusting motor, the driving gear and the driven gear are connected through an intermediate gear, and the rotary locking device is matched with the intermediate gear to lock or unlock.

3. An automatic hitching three-point linkage of an agricultural implement according to claim 1, characterized in that: The rotary locking device comprises a fixed block fixed to the front beam frame, a lock tongue is arranged in the fixed block in a sliding manner, a locking tooth is arranged at the inner end of the lock tongue, a locking tension spring is arranged between the outer end of the lock tongue and the fixed block, a lock tongue rack is arranged at the outer end of the lock tongue, and an unlocking motor is fixed to the front beam frame, an unlocking gear is mounted at the output end of the unlocking motor, and the unlocking gear is engaged with the lock tongue rack.

4. An automatic hitching three-point linkage of an agricultural implement according to claim 1, characterized in that: The power docking device comprises a mounting shell fixed to the rear beam frame, a bearing seat is arranged in the mounting shell in a sliding manner, a spline shaft sleeve is arranged in the bearing seat in a rotating manner, a shaft coupling is connected to the front end of the spline shaft sleeve, an internal spline is processed at the rear end of the spline shaft sleeve, a power docking oil cylinder is arranged between the mounting shell and the bearing seat, the power docking oil cylinder drives the bearing seat to slide in an extending or retracting manner, so that the spline shaft sleeve is combined with or separated from a spline shaft.

5. An automatic hitching three-point linkage of an agricultural implement according to claim 1, characterized in that: The left lower hook comprises a first hook base, a first hooking pin hole and a first hooking opening communicated with the first hooking pin hole are arranged in the first hook base, a first sliding block guide groove is arranged in the first hook base corresponding to the first hooking opening, a first hooking sliding block is slidably arranged in the first sliding block guide groove, a first guide arc surface curved towards one side of the first hooking pin hole is arranged on the opening end of the first hooking sliding block, a first locking tension spring is arranged between the tail end of the first hooking sliding block and the first hook base, a first locking positioning member is arranged between the first hooking sliding block and the first hook base, and a first electric control unlocking device overcoming the first locking tension spring is further arranged on the first hooking sliding block; the first electric control unlocking device comprises a first unlocking motor arranged on the first hook base, a first unlocking gear is arranged on the output end of the first unlocking motor, a first sliding block rack is arranged on the surface of the first hooking sliding block away from the first hooking pin hole, and the first unlocking gear and the first sliding block rack are transmissionally matched.

6. An automatic hitching three-point linkage of an agricultural implement according to claim 1, characterized in that: The right lower hook comprises a second hook base, a second hooking pin hole and a second hooking opening communicated with the second hooking pin hole are arranged in the second hook base, a second sliding block guide groove is arranged in the second hook base corresponding to the second hooking opening, a second hooking sliding block is slidably arranged in the second sliding block guide groove, a second guide arc surface curved towards one side of the second hooking pin hole is arranged on the opening end of the second hooking sliding block, a second locking tension spring is arranged between the tail end of the second hooking sliding block and the second hook base, a second locking positioning member is arranged between the second hooking sliding block and the second hook base, and a second electric control unlocking device overcoming the second locking tension spring is further arranged on the second hooking sliding block; the second electric control unlocking device comprises a second unlocking motor arranged on the second hook base, a second unlocking gear is arranged on the output end of the second unlocking motor, a second sliding block rack is arranged on the surface of the second hooking sliding block away from the second hooking pin hole, and the second unlocking gear and the second sliding block rack are transmissionally matched.

7. An automatic hitching three-point linkage of an agricultural implement according to claim 1, characterized in that: The upper hook comprises a third hook base, a third hooking pin hole and a third hooking opening communicated with the third hooking pin hole are arranged in the third hook base, a third sliding block guide groove is arranged in the third hook base corresponding to the third hooking opening, a third hooking sliding block is slidably arranged in the third sliding block guide groove, a third guide arc surface curved towards one side of the third hooking pin hole is arranged on the opening end of the third hooking sliding block, a third locking tension spring is arranged between the tail end of the third hooking sliding block and the third hook base, a third locking positioning member is arranged between the third hooking sliding block and the third hook base, and a third electric control unlocking device overcoming the third locking tension spring is further arranged on the third hooking sliding block; the third electric control unlocking device comprises a third unlocking motor arranged on the third hook base, a third unlocking gear is arranged on the output end of the third unlocking motor, a third sliding block rack is arranged on the surface of the third hooking sliding block away from the third hooking pin hole, and the third unlocking gear and the third sliding block rack are transmissionally matched.

8. An automatic hitching three-point linkage of an agricultural implement according to claim 1, characterized in that: The telescopic connecting arm comprises a supporting arm and an extension arm sleeved in the supporting arm, a positioning hole is arranged between the supporting arm and the extension arm, the rear end of the supporting arm is fixed on the front beam frame, a connecting fulcrum plate is further arranged on the top of the rear end of the supporting arm, and the front end of the extension arm is provided with an extension arm connecting hole.

9. An automatic hitching three-point linkage of an agricultural implement according to claim 1, characterized in that: The upper oil cylinder assembly comprises an upper oil cylinder one and an upper oil cylinder two, one end of the upper oil cylinder one is hinged to the rear axle of the tractor, an upper hook is arranged at the bottom of the other end of the upper oil cylinder one, one end of the upper oil cylinder two is hinged to the rear axle of the tractor, and the other end of the upper oil cylinder two is hinged to the upper oil cylinder one.

10. An automatic hitching three-point linkage of an agricultural implement according to claim 1, characterized in that: A main controller is arranged below the power docking device on the rear beam frame.

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