Four-wheel-drive speed change mechanism and four-wheel-drive agricultural machine

Abstract

The four-wheel-drive speed change mechanism comprises a front speed change mechanism body and a rear speed change mechanism body, the front speed change mechanism body comprises a front power shaft and a front output shaft which are arranged in parallel, and a front speed change gear set is arranged between the front power shaft and the front output shaft; the rear speed change mechanism comprises a rear output shaft and a rear power shaft which are arranged in parallel, and a rear speed change gear set with a neutral position is arranged between the rear output shaft and the rear power shaft; a front combining piece and a rear combining piece which are arranged side by side are arranged at the ends, opposite to the rear output shaft, of the front output shaft, and a combining mechanism used for connecting the front combining piece and the rear combining piece in a transmission mode is arranged on the rear power shaft in an axial sliding and sleeving mode. A shifting fork mechanism used for driving the combining mechanism to move axially is arranged on the combining mechanism in a matched mode. The four-wheel-drive speed change mechanism and the four-wheel-drive agricultural machine have the advantages of being ingenious in structural design, capable of achieving simultaneous driving of the front wheel and the rear wheel under the walking working condition and the like.

Description

Technical Field

[0001] The utility model relates to the technical field of agricultural machinery, in particular to a four-wheel drive speed change mechanism and a four-wheel drive agricultural machine. Background Art

[0002] A rotary tiller is a tilling machine that completes plowing and weeding. It is widely used because of its strong soil crushing ability and flat surface after plowing. It has developed from the original hand-held micro-tiller to the more efficient high-power rotary tiller, both of which have been accepted by the majority of farmers. The basic principle of the rotary tiller is to use the rotating knife disc to deeply plow, loosen and compact the land through the special structure of the machine body.

[0003] The original hand-held rotary tiller can meet the needs of most individual users, but it requires a lot of physical strength to operate, and the operation is complicated and dangerous. Based on this, a riding rotary tiller with low labor intensity and high efficiency has also appeared on the market. The riding rotary tiller includes a rotary tilling wheel axle and a traveling wheel axle. Under working conditions, a rotary tilling wheel axle is installed with a rotary tilling wheel for rotary tilling operations, and a tire is installed on the traveling wheel axle to assist walking. Under road walking conditions, tires are installed on both the rotary tilling wheel axle and the traveling wheel axle for walking. However, in order to ensure the effect of rotary tillage, the rotation speed of the rotary tilling wheel axle is usually greater than the rotation speed of the traveling wheel axle. This makes it impossible for the existing riding rotary tiller to achieve simultaneous driving of the front and rear wheels under road walking conditions. Utility Model Content

[0004] In view of the above-mentioned deficiencies in the prior art, the technical problem to be solved by the present invention is: how to provide a four-wheel drive transmission mechanism and a four-wheel drive agricultural machine with an ingenious structural design that can realize simultaneous driving of the front and rear wheels under traveling conditions.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A four-wheel drive transmission mechanism includes a front transmission mechanism and a rear transmission mechanism, the front transmission mechanism includes a front power shaft and a front output shaft arranged in parallel, and a front transmission gear set is arranged between the front power shaft and the front output shaft; the rear transmission mechanism includes a rear output shaft and a rear power shaft arranged in parallel, and a rear transmission gear set with a neutral gear is arranged between the rear output shaft and the rear power shaft; the front output shaft has a front coupling and a rear coupling arranged side by side at one end opposite to the rear output shaft, and the rear power shaft is axially slidably provided with a coupling mechanism for transmission connection between the front coupling and the rear coupling, and the coupling mechanism is matched with a shift fork mechanism for driving the coupling mechanism axial movement.

[0007] With the above structure, under traveling conditions, the rear speed-change gear set can be set in neutral, and the coupling mechanism can be moved along the rear power shaft by the shift fork mechanism to a state where it connects the front coupling member and the rear coupling member, so that the front output shaft and the rear output shaft are coaxially connected. After power is input through the front power shaft, it is transmitted to the front output shaft through the front speed-change gear set, thereby allowing the front output shaft and the rear output shaft to output power at the same speed. Under working conditions, the coupling mechanism is moved by the shift fork mechanism to disengage the front coupling member and the rear coupling member, and the speeds of the front output shaft and the rear output shaft are controlled by the front speed-change gear set and the rear speed-change gear set, respectively.

[0008] Furthermore, the front output shaft is coaxially arranged with the rear output shaft, the front coupling and the rear coupling are synchronous gears with the same parameters, the coupling mechanism is a transmission gear that can engage with the synchronous gear, the thickness of the transmission gear is greater than the spacing between the two synchronous gears, and can be axially moved to a position where it engages with the two synchronous gears at the same time.

[0009] In this way, the transmission gear is moved along the rear power shaft by the shift fork mechanism to a state where the two synchronous gears are engaged at the same time, and the two synchronous gears can maintain a coaxial connection under the action of the meshing teeth.

[0010] Furthermore, a double gear is relatively rotatably mounted on the front output shaft, and the double gear includes a first gear and a second gear that can mesh with the transmission gear. An input gear that meshes with the first gear is fixedly arranged on the front power shaft; the transmission gear can be axially slidably fitted on the rear power shaft through a spline connection structure, and can be axially moved to a position where it meshes with the second gear.

[0011] In this way, under working conditions, the transmission gear is moved to a position meshing with the second gear by the shift fork mechanism, so that after power is input through the front power shaft, it is transmitted to the duplex gear through the input gear. Since the duplex gear is relatively rotatably sleeved on the front output shaft, the rotation of the duplex gear does not affect the state of the front output shaft. The power is transmitted to the transmission gear through the second gear of the duplex gear. Since the transmission gear is matched with the rear power shaft through the spline connection structure, the transmission gear can drive the rear power shaft to rotate and transmit it to the rear output shaft through the rear speed gear set.

[0012] As another optimization, the front coupling member is a coupling sleeve mounted on the front output shaft, and the coupling sleeve can be axially slidably fitted on the front output shaft through a spline connection structure. The rear coupling member is a coupling tooth circumferentially arranged on the rear output shaft, and the inner hole of the coupling sleeve on the side facing the rear output shaft has a coupling groove matching the coupling tooth, and the coupling groove can be sleeved on the coupling tooth; the outer circumferential surface of the coupling sleeve has an annular groove extending circumferentially, and the coupling mechanism is a driving disk axially slidably mounted on the rear power shaft, and the thickness of the driving disk matches the width of the annular groove and is fitted in the annular groove.

[0013] As another optimization, the front coupling is a front synchronous gear sleeved on the front output shaft, the rear coupling is a rear synchronous gear arranged on the rear output shaft, and the coupling mechanism is a double-arranged front transmission gear and rear transmission gear, and the front transmission gear and rear transmission gear can be respectively engaged with the front synchronous gear and the rear synchronous gear at the same time.

[0014] Furthermore, the rear speed gear set includes a rear shift gear that is axially movably engaged with the rear power shaft through a spline connection structure, and the rear shift gear is equipped with a rear shift fork mechanism for driving the rear shift gear to move axially; the coupling mechanism has a limit sleeve extending toward the rear shift gear, and the limit sleeve is in close contact with the rear shift gear in the neutral position when the coupling mechanism transmission connects the front coupling member and the rear coupling member.

[0015] In this way, it can be ensured that when the front coupling member and the rear coupling member are coaxially connected, the rear speed change gear set is reliably in a neutral state, thereby avoiding operational failures.

[0016] Furthermore, the rear shift gear includes a double-connected rear active low-speed gear and a rear active high-speed gear, and the rear active low-speed gear is located on the side facing the limit sleeve; the rear output shaft is fixedly provided with a rear driven low-speed gear and a rear driven high-speed gear which can respectively engage with the rear active low-speed gear and the rear active high-speed gear.

[0017] In this way, moving the rear shift gear toward the limiting sleeve can mesh the rear active low-speed gear with the rear driven low-speed gear, driving the rear output shaft to rotate at a low speed; moving the rear shift gear away from the limiting sleeve can mesh the rear active high-speed gear with the rear driven high-speed gear, driving the rear output shaft to rotate at a high speed. Under the running condition, the coupling mechanism is moved and the limiting sleeve is used to further push the rear shift gear outward. After the rear active high-speed gear and the rear driven high-speed gear are disengaged, the rear active low-speed gear and the rear driven high-speed gear are directly opposite each other. Since the sum of the radii of the two is less than the center distance between the two, the rear shift gear set is in a neutral position.

[0018] Furthermore, the front power shaft is axially movably equipped with a low-speed gear driving gear through a spline connection structure, and the low-speed gear driving gear is equipped with a second fork mechanism for driving the low-speed gear driving gear to axially move; the front output shaft is fixedly provided with a low-speed gear driven gear that can mesh with the low-speed gear driving gear.

[0019] Furthermore, the front transmission mechanism includes an intermediate shaft arranged parallel to the front power shaft, and a reverse gear is provided on the intermediate shaft. The reverse gear includes a first reversing gear and a second reversing gear arranged in duplex, the first reversing gear is engaged with the low-speed gear driven gear, and the second reversing gear is matched with the low-speed gear driving gear, and the low-speed gear driving gear can slide axially to engage with the second reversing gear.

[0020] A four-wheel drive agricultural machine comprises the four-wheel drive speed change mechanism described above.

[0021] In summary, the four-wheel drive transmission mechanism and the four-wheel drive agricultural machine of the present invention have the advantages of clever structural design and the ability to achieve simultaneous driving of the front and rear wheels under traveling conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 and Figure 2 This is a structural diagram of the operating status of Example 1.

[0023] Figure 3 and Figure 4 This is a structural diagram of the walking state of Example 1.

[0024] Figure 5 This is a schematic diagram of the principle of the walking state of Example 2.

[0025] Figure 6 This is a schematic diagram of the principle of the walking state of Example 3. DETAILED DESCRIPTION

[0026] The present invention will be further described in detail below with reference to the embodiments.

[0027] Example 1: Figures 1 to 4As shown, a four-wheel drive transmission mechanism includes a front transmission mechanism for front drive and a rear transmission mechanism for rear drive, the front transmission mechanism includes a front power shaft 1 and a front output shaft 2 arranged in parallel, and a front transmission gear set 5 is arranged between the front power shaft 1 and the front output shaft 2; the rear transmission mechanism includes a rear output shaft 3 and a rear power shaft 4 arranged in parallel, and a rear transmission gear set 6 with a neutral gear is arranged between the rear output shaft 3 and the rear power shaft 4; the front output shaft 2 has a front coupling 71 and a rear coupling 72 arranged side by side at one end opposite to the rear output shaft 3, and the rear power shaft 4 is axially slidably provided with a coupling mechanism 73 for transmission connection between the front coupling 71 and the rear coupling 72, and the coupling mechanism 73 is matched with a fork mechanism for driving the coupling mechanism 73 axially to move.

[0028] In this embodiment, the front output shaft 2 is coaxially arranged with the rear output shaft 3. The front coupling member 71 and the rear coupling member 72 are synchronous gears with identical parameters. The coupling mechanism 73 is a transmission gear that can mesh with the synchronous gears. The transmission gear has a thickness greater than the spacing between the two synchronous gears and is axially movable to a position where it can simultaneously mesh with both synchronous gears. To more reliably connect the two synchronous gears, the thickness of the transmission gear matches the sum of the thicknesses of the two synchronous gears.

[0029] Specifically, a double gear 74 is relatively rotatably sleeved on the front output shaft 2, and the double gear 74 includes a first gear 741 and a second gear 742 that can mesh with the transmission gear. An input gear 75 that meshes with the first gear 741 is fixedly provided on the front power shaft 1; the transmission gear can be axially slidably fitted on the rear power shaft 4 through a spline connection structure, and can be axially moved to a position meshing with the second gear 742.

[0030] In this way, during operation, the shift fork mechanism moves the transmission gear to a position where it meshes with the second gear. This allows power to be input through the front power shaft and then transmitted to the duplex gear via the input gear. Since the duplex gear is rotatably mounted on the front output shaft, the rotation of the duplex gear does not affect the state of the front output shaft. Power is then transmitted to the transmission gear via the second gear of the duplex gear. Since the transmission gear is mated to the rear power shaft via a spline connection, the transmission gear can drive the rear power shaft to rotate and then be transmitted to the rear output shaft via the rear speed gear set. During travel, the shift fork mechanism moves the transmission gear to a position where it meshes with both synchronous gears simultaneously, placing the rear speed gear set 6 in neutral. Power is then input through the front power shaft and transmitted to the front output shaft via the front speed gear set 5. Then, it is transmitted to the rear output shaft via the two coaxially connected synchronous gears. At this point, the transmission gear drives the rear power shaft to idle.

[0031] The front speed gear set 5 includes a front shift gear 51 that is axially movably engaged with the front power shaft 1 through a spline connection structure, and the front shift gear 51 is equipped with a first shift fork mechanism for driving the front shift gear 51 to move axially; the front shift gear 51 includes a first gear driving gear and a second gear driving gear that are arranged in a double connection, and the diameter of the first gear driving gear is larger than the diameter of the second gear driving gear; the front output shaft 2 is fixedly provided with a first gear driven gear 52 and a second gear driven gear 53 that can respectively mesh with the first gear driving gear and the second gear driving gear. In this embodiment, the front power shaft 1 is axially movably equipped with a low-speed gear driving gear 54 through a spline connection structure. The diameter of the low-speed gear driving gear 54 is smaller than the diameter of the second-speed gear driving gear and is located on the side of the second-speed gear driving gear away from the first-speed gear driving gear; a low-speed gear driven gear 55 that can mesh with the low-speed gear driving gear 54 is fixedly provided on the front output shaft 2, and the low-speed gear driving gear 54 is equipped with a second fork mechanism for driving the low-speed gear driving gear 54 to axially move, so that the low-speed gear driving gear 54 can axially move to a position meshing with the low-speed gear driven gear 55.

[0032] In order to achieve reverse gear, the front speed change mechanism includes an intermediate shaft 56 arranged parallel to the front power shaft 1, and a reverse gear 57 is provided on the intermediate shaft 56. The reverse gear 57 includes a first reversing gear and a second reversing gear arranged in pairs. The first reversing gear is engaged with the low-speed gear driven gear 55, and the second reversing gear is matched with the low-speed gear driving gear 54. The low-speed gear driving gear 54 can slide axially to engage with the second reversing gear.

[0033] In this way, when the first gear driving gear is engaged with the first gear driven gear, the front output shaft rotates at high speed; when the second gear driving gear is engaged with the second gear driven gear, the front output shaft rotates at medium speed; when the low speed gear driving gear is engaged with the low speed gear driven gear, the front output shaft rotates at low speed.

[0034] The rear speed gear set 6 includes a rear shift gear 61 that is axially movably engaged with the rear power shaft 4 through a spline connection structure, and the rear shift gear 61 is equipped with a rear shift fork mechanism for driving the rear shift gear 61 to move axially; the coupling mechanism 73 has a limiting sleeve 76 extending toward the rear shift gear 61, and the limiting sleeve 76 can be close to the rear shift gear 61 in the neutral position when the transmission gear connects the two synchronous gears.

[0035] Specifically, the rear shift gear 61 includes a dual-arranged rear driving low-speed gear and a rear driving high-speed gear, and the rear driving low-speed gear is located on the side facing the limiting sleeve 76; the rear output shaft 3 is fixedly provided with a rear driven low-speed gear 62 and a rear driven high-speed gear 63 that can respectively engage with the rear driving low-speed gear and the rear driving high-speed gear; the sum of the radius of the rear driving low-speed gear and the radius of the rear driven high-speed gear 63 is less than the center distance between the two.

[0036] In this way, moving the rear shift gear toward the stop sleeve engages the rear driving low-speed gear with the rear driven low-speed gear, driving the rear output shaft to rotate at a low speed. Moving the rear shift gear away from the stop sleeve engages the rear driving high-speed gear with the rear driven high-speed gear, driving the rear output shaft to rotate at a high speed. During driving, the rear shift gear 61 is first moved away from the stop sleeve to a neutral position. The coupling mechanism, i.e., the transmission gear, is then moved. This allows the transmission gear to simultaneously engage with both synchronous gears, establishing a transmission connection between the front and rear output shafts. Power is then directly transmitted from the front output shaft to the rear output shaft. At this point, the stop sleeve is in close contact with the rear shift gear 61. In other words, if the rear shift gear 61 is not moved to the neutral position and the transmission gear is moved directly, the stop sleeve will abut against the rear shift gear before the transmission gear engages with the two synchronous gears, preventing the transmission gear from further engaging with the synchronous gears. This provides a misplacement function and prevents damage to the transmission mechanism.

[0037] When the four-wheel drive transmission mechanism of this embodiment is used, under working conditions, the transmission gear is meshed with the second gear, and the engine power is transmitted to the front power shaft. Part of it is transmitted to the front output shaft through the front speed gear set for front drive output; part of it is transmitted to the rear power shaft through the input gear, duplex gear and transmission gear, and then transmitted to the rear output shaft through the rear speed gear set for rear drive output.

[0038] Under the walking condition, the transmission gear is engaged with the two synchronous gears at the same time, and the rear speed gear set is in the neutral position. The engine power is transmitted to the front power shaft, and then transmitted to the front output shaft through the front speed gear set. The synchronous gears of the front output shaft and the rear output shaft are coaxially connected with the cooperation of the transmission gear. The power is directly transmitted from the front output shaft to the rear output shaft, so that the front output shaft and the rear output shaft are output to the front and rear drives at the same speed, thereby realizing four-wheel drive under the walking condition.

[0039] Example 2: The main difference between this example and Example 1 is that Figure 5As shown, the front coupling member 71 is a coupling sleeve mounted on the front output shaft 2, and the coupling sleeve can be axially slidably fitted on the front output shaft 2 through a spline connection structure. The rear coupling member 72 is a coupling tooth circumferentially arranged on the rear output shaft 3, and the inner hole of the coupling sleeve on the side facing the rear output shaft 3 has a coupling groove matching the coupling tooth, and the coupling groove can be sleeved on the coupling tooth; the outer circumferential surface of the coupling sleeve has an annular groove extending circumferentially, and the coupling mechanism 73 is a driving disk axially slidably mounted on the rear power shaft 4, and the thickness of the driving disk matches the width of the annular groove and is fitted in the annular groove.

[0040] A double gear 74 is relatively rotatably sleeved on the front output shaft 2, and the double gear 74 includes a first gear 741 and a second gear 742 that can mesh with the transmission gear. An input gear 75 that meshes with the first gear 741 is fixedly provided on the front power shaft 1; transmission gears that can mesh with the second gear 742 are connected side by side on the drive plate, and the transmission gear can be axially slidably fitted on the rear power shaft 4 through a spline connection structure, and can be axially moved to a position where it meshes with the second gear 742.

[0041] In this embodiment, the drive disc fits within an annular groove on the surface of the coupling sleeve. The sidewalls of the annular groove limit the axial direction of the drive disc, ensuring that the rotation of the two does not interfere with each other. By moving the drive disc and transmission gear axially, when the transmission gear engages with the second gear, the coupling groove on the coupling sleeve disengages the coupling teeth on the rear output shaft. When the coupling groove on the coupling sleeve engages the coupling teeth on the rear output shaft, the transmission gear separates from the second gear. This also enables switching between operating and traveling modes.

[0042] Example 3: The main difference between this example and Example 1 is that Figure 6 As shown, the front output shaft 2 and the rear output shaft 3 are staggered, the front coupling 71 is a front synchronous gear sleeved on the front output shaft 2, the rear coupling 72 is a rear synchronous gear provided on the rear output shaft 3, and the coupling mechanism 73 is a double-connected front transmission gear and a rear transmission gear, and the front transmission gear and the rear transmission gear can be respectively engaged with the front synchronous gear and the rear synchronous gear at the same time.

[0043] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A four-wheel drive transmission mechanism, comprising a front transmission mechanism and a rear transmission mechanism, characterized in that: The front speed change mechanism comprises a front power shaft (1) and a front output shaft (2) arranged in parallel, and a front speed change gear set (5) is arranged between the front power shaft (1) and the front output shaft (2); the rear speed change mechanism comprises a rear output shaft (3) and a rear power shaft (4) arranged in parallel, and a rear speed change gear set (6) with a neutral gear is arranged between the rear output shaft (3) and the rear power shaft (4); the front output shaft (2) has a front coupling member (71) and a rear coupling member (72) arranged side by side at one end opposite to the rear output shaft (3); a coupling mechanism (73) for connecting the front coupling member (71) and the rear coupling member (72) in a transmission manner is axially slidably sleeved on the rear power shaft (4), and the coupling mechanism (73) is matched with a shift fork mechanism for driving the coupling mechanism (73) to move axially.

2. The four-wheel drive transmission mechanism according to claim 1, wherein: The front output shaft (2) and the rear output shaft (3) are coaxially arranged, the front coupling member (71) and the rear coupling member (72) are synchronous gears with the same parameters, the coupling mechanism (73) is a transmission gear that can mesh with the synchronous gears, the thickness of the transmission gear is greater than the spacing between the two synchronous gears, and the transmission gear can be axially moved to a position where it meshes with the two synchronous gears at the same time.

3. The four-wheel drive transmission mechanism according to claim 2, wherein: A double gear (74) is relatively rotatably sleeved on the front output shaft (2), the double gear (74) comprising a first gear (741) and a second gear (742) meshing with the transmission gear; an input gear (75) meshing with the first gear (741) is fixedly provided on the front power shaft (1); the transmission gear is axially slidably engaged with the rear power shaft (4) via a spline connection structure, and can be axially moved to a position meshing with the second gear (742).

4. The four-wheel drive transmission mechanism according to claim 1, wherein: The front coupling member (71) is a coupling sleeve sleeved on the front output shaft (2), and the coupling sleeve can be axially slidably fitted on the front output shaft (2) through a spline connection structure. The rear coupling member (72) is a coupling tooth circumferentially arranged on the rear output shaft (3). The inner hole of the coupling sleeve on one side facing the rear output shaft (3) has a coupling groove matching the coupling tooth, and the coupling groove can be sleeved on the coupling tooth; the outer circumferential surface of the coupling sleeve has an annular groove extending in the circumferential direction. The coupling mechanism (73) is a driving disk axially slidably sleeved on the rear power shaft (4), and the thickness of the driving disk matches the width of the annular groove and is fitted in the annular groove.

5. The four-wheel drive transmission mechanism according to claim 1, wherein: The front coupling member (71) is a front synchronous gear sleeved on the front output shaft (2), the rear coupling member (72) is a rear synchronous gear arranged on the rear output shaft (3), and the coupling mechanism (73) is a double-arranged front transmission gear and a rear transmission gear, and the front transmission gear and the rear transmission gear can be respectively engaged with the front synchronous gear and the rear synchronous gear at the same time.

6. The four-wheel drive transmission mechanism according to any one of claims 1 to 5, characterized in that: The rear speed gear set (6) includes a rear shift gear (61) that is axially movably engaged with the rear power shaft (4) through a spline connection structure, and the rear shift gear (61) is engaged with a rear shift fork mechanism for driving the rear shift gear (61) to axially move; the coupling mechanism (73) has a limiting sleeve (76) extending toward the rear shift gear (61), and the limiting sleeve (76) is in close contact with the rear shift gear (61) in the neutral position when the coupling mechanism (73) drives the front coupling member (71) and the rear coupling member (72).

7. The four-wheel drive transmission mechanism according to claim 6, wherein: The rear shift gear (61) includes a dual-arranged rear active low-speed gear and a rear active high-speed gear, wherein the rear active low-speed gear is located on a side facing the limiting sleeve (76); and a rear driven low-speed gear (62) and a rear driven high-speed gear (63) are fixedly arranged on the rear output shaft (3) and are respectively meshed with the rear active low-speed gear and the rear active high-speed gear.

8. The four-wheel drive transmission mechanism according to claim 1, wherein: The front power shaft (1) is axially movably matched with a low-speed gear driving gear (54) via a spline connection structure, and the low-speed gear driving gear (54) is matched with a second shift fork mechanism for driving the low-speed gear driving gear (54) to axially move; and the front output shaft (2) is fixedly provided with a low-speed gear driven gear (55) that can mesh with the low-speed gear driving gear (54).

9. The four-wheel drive transmission mechanism according to claim 8, characterized in that: The front speed change mechanism comprises an intermediate shaft (56) arranged in parallel with the front power shaft (1); a reverse gear (57) is arranged on the intermediate shaft (56); the reverse gear (57) comprises a first reversing gear and a second reversing gear arranged in a double connection; the first reversing gear is meshed with the low-speed gear driven gear (55); the second reversing gear is matched with the low-speed gear driving gear (54); the low-speed gear driving gear (54) can slide axially to mesh with the second reversing gear.

10. A four-wheel drive agricultural machine, characterized in that: It comprises the four-wheel drive transmission mechanism according to any one of claims 1 to 9.

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