JP4867115B2 - Agricultural tractor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
This inventionAgricultural tractorIn particular,Use only crawlers in the running sectionCrawler typeTractorAbout.
[0002]
[Prior art]
2. Description of the Related Art A mobile vehicle such as an agricultural tractor whose traveling unit is a crawler is known.
In general, such a moving vehicle has a drive sprocket attached to a drive shaft that protrudes laterally from the rear mission case, and a traveling wheel provided along the front-rear direction at the lower side thereof is provided with driven wheels, respectively. A plurality of wheels are mounted between the driven wheels, and a traveling portion is formed by winding a crawler having a triangular shape in a side view between the drive sprocket and the driven wheels.
[0003]
[Problems to be solved by the invention]
By the way, in such a moving vehicle, there is no ingenuity in how to attach the follower wheel to the frame, how to support the wheel, or the structure of the frame itself. On the other hand, if the frame was made strong with emphasis on strength, mud removal was bad. On the other hand, if the frame was made simple, problems such as deformation of the frame due to crawler mud pushing during turning occurred.
[0004]
Agricultural tractors must not only travel in the field, but also frequently go over a steep ridge, etc., but if you try to turn the steering handle on a sloping ground, the front lower part of the crawler will loosen. There was a problem that a part of the wheel was detached from the crawler.
[0005]
[Means for Solving the Problems]
The present invention is proposed in view of the above-mentioned problems, and therefore the following technical means have been taken.
[0006]
That is, according to the first aspect of the invention, the drive sprocket (7) attached to the drive shaft (5) protruding from the rear mission case (4) connected to the rear portion of the transmission case (3) and the crawler frame (10) are attached. In the agricultural tractor formed only by the crawler traveling portion by winding the crawler (8) around the two front and rear driven wheels (11), (12) and the plurality of rolling wheels (13), the crawler frame (10) Separately, a main frame (14) extending in the front-rear direction is provided at the lower part of the vehicle body, and the main frame (14) and the crawler frame (10) are formed by front and rear longitudinal frames (15), (15). Concatenate,
The distance between the rear oscillating roller (13b) and the rearmost roller (13d) is minimized, and the interval between the oscillating rollers is larger than that. The front oscillating roller (13a) and the frontmost roller The distance between the wheel (13c) is larger than the distance between the oscillating wheels.
The rear wheel (12) and the rear wheel (13d) are partially overlapped with each other when the rear wheel (12) and the rear wheel (13d) are viewed from the side, with the center position of the rear wheel (13d) positioned behind the center position of the drive sprocket (7). The rear end of the rear driven wheel (12) is inserted into the recess (13s) of the rearmost wheel (13d) and overlapped.
A rear axle case (18) is formed on the rear transmission case (4), and a flat plate (17) is fixedly attached to the upper portion of the rear vertical frame (15) in a forwardly lowered posture, and the flat plate (17) is provided on the rear axle. A reinforcement pipe (40) is provided that is fixed by pressing against the lower surface of the case (18) and obliquely connects the rear vertical frame (15) and the rear part of the crawler frame (10). An agricultural tractor characterized in that the frame (15) is connected to the flat plate (17) to receive the load of the airframe.
[0007]
According to a second aspect of the present invention, the front swing wheel (13a) and the rear swing wheel (13b) are supported by swing arms (26), (26), and the swing arms (26), (26). The swing center of is characterized in that it is smaller than that formed between the line segment connecting the centers of the respective rolling wheels in the horizontal state and the line segment connecting the centers of the front and rear driven wheels (11), (12). The mobile vehicle according to claim 1.
[0008]
In this configuration, when the rotational power of the engine 2 is transmitted to the driving sprocket 7, the crawler 8 is rotated by the driving force, and the agricultural tractor 1 travels in a wet field or the like.
Most of the driven wheels 11 and 12 and the rolling wheels 13 are buried in the mud during running and continue running in that state. When the steering wheel is operated to turn the airframe, the crawler frame 10 and the driven wheels 11 and 12 are subjected to a lateral load due to mud. Therefore, the crawler frame 10 receives a bending load from the side and the mud is The crawler frame 10 tries to enter the inside of the crawler frame 10. The crawler frame 10 is connected to the main frame 14 and the vertical frame 15 above the crawler frame 10, and the main frame 14 itself is attached to the vehicle body side which is a rigid body. Is strong enough to withstand the heavy loads of mud. Further, since the muddy soil is moved through the space surrounded by the crawler frame 10, the main frame 14, and the vertical frame 15, the pressure of the soil acting on the frame is reduced, and the deformation of the crawler frame 10 can be reduced.
In addition, when the aircraft is moving forward and traveling on a soft field such as a wet paddy field, the aircraft is in a front-up position, but the downward load from the rear axle case (18) is not directly applied to the rear vertical frame (15). The aircraft is stable.
[0009]
Embodiment
Embodiments of the present invention will be described below based on the embodiments shown in the drawings. First, the construction will be described. Reference numeral 1 is an agricultural tractor, and the traveling part is a crawler 8. The rotational power of the engine 2 mounted on the front part of the machine body is transmitted to the transmission in the transmission case 3, and the shifted power is transmitted to the rear. The transmission is transmitted from the transmission case 4 to the drive sprockets 7 and 7 attached to the drive shafts 5 and 5 protruding laterally from side to side.
[0010]
Reference numerals 10 and 10 denote crawler frames made of square pipes provided along the front-rear direction. The crawler frames are provided with front and rear driven wheels 11 and 12, and a plurality of wheels 13 are supported in the middle. The crawler 2 is wound between the drive sprocket 7 and the front and rear driven wheels 11 and 12 and the rolling wheels 13..., And has a substantially triangular shape when viewed from the side.
[0011]
The main frames 14 and 14 provided above the crawler frames 10 and 10 in parallel with the crawler frames 10 and 10 are formed of square pipe members having strength, and the crawler frames 10 and 10 and the main frames 14 and 14 are in the vertical direction. Are connected by vertical frames 15, 15, and a space portion A in which mud mud can be laterally moved is formed in a portion surrounded by these frames 10, 10, 14, 14, 15, 15.
[0012]
Flat plates 17 and 17 are fixed to the upper part of the rear vertical frame 15 in a forwardly lowered posture. The flat plates 17 and 17 are pressed against the lower surfaces of the rear axle cases 18 and 18 and fixed with bolts 19 and 19.
One end of a frame 20, 20 formed of a square pipe extending obliquely upward when viewed from the side is fixed to the body frames 21, 21 by bolts 22, 22 at the front portions of the main frames 14, 14. .
[0013]
Among the rollers 13 attached to the crawler frames 10, 10, the two center rollers 13a, 13b are supported by swing arms 26, 26 that swing around fulcrums 25, 25. 26, springs 27, 27 urge the front wheels 13a, 13a upward. The springs 27, 27 are interposed between bolts 29, 29 attached to the outside of the plates 28, 28 connecting the main frame 14 and the front and rear intermediate portions of the crawler frame 10 and the swing arms 26, 26. You may form with the compression spring which presses the rear part of the rocking | swiveling arms 28 and 28 downward.
[0014]
The foremost rollers 13c and 13c and the rearmost rollers 13d and 13d are both rotatably supported by the crawler frames 10 and 10 by pins 30 and 30, respectively. These front and rear rollers 13c, 13c, 13d, and 13d are all supported in a cantilevered state, and the center swinging rollers 13a and 13b are rotatably supported by pins 31 and 31 on swinging arms 26 and 26. The
[0015]
As is apparent from FIG. 3, the swing center of the swing arms 26 and 26 is between the line segment connecting the centers of the respective rolling wheels in the horizontal state and the line segment connecting the centers of the front and rear driven wheels 11 and 12. In this way, the restoring property of the swinging rollers 13a and 13b is improved.
[0016]
If the swinging center position of the swinging arms 26, 26 is too high, the swinging arms 26, 26 may be pushed by the mud and turn the whole, while if too low, the followability is poor. Although it occurs, it has been confirmed by a test that the reversibility of the swing arms 26 and 26 is improved and the followability to the unevenness of the field is improved when configured as in this embodiment. Further, as apparent from the figure, the width (vertical direction) of the crawler frames 10, 10 is made smaller than the diameter of the rolling wheels 13, so that the outer surfaces of the crawler frames 10, 10 do not become walls. Thus, when traveling on a muddy field in the field, there is no hindrance to the movement of the mud in the horizontal direction, and therefore no mud is collected in the crawler frames 10 and 10.
[0017]
3 and 4, the rear driven wheel 12 and the rearmost wheel 13d are partially wrapped when viewed from the side, and the distance between the wheels 13, 13 is narrow on the rear side and the front side is The configuration is wide.
In this embodiment, the distance between the rear-side rocking wheel 13b and the rearmost wheel 13d is minimized, the distance between the rocking wheels is slightly larger than that, and the front-side rocking wheel 13a and the foremost wheel are rotated. The distance from the wheel 13c is slightly larger than that, and the distance is increased sequentially.
[0018]
This is due to the following reason. That is, when the crawler 8 moves forward in the field, the front part of the crawler 8 is lifted by the reaction force from the ground. In order to support this reaction force with a large number of the rollers 13 and reduce the load sharing per roller, it is necessary to support the crawler 8 with a small interval between the rollers. In this way, by narrowing the rear spacing and making the distribution of the wheels dense, the load applied to the rear wheels is reduced, and the wheels are prevented from being damaged and the durability is improved.
[0019]
The rear driven wheel 12 is configured to be detachable at the rear ends of the crawler frames 10, 10. Specifically, two plates are provided at the front portions of the boss portions 33, 33 that support the rear driven wheel 12. 34 and 34 are fixed, and screw holes 35 and 35 are formed in the upper and lower portions of the plates 34 and 34. The screw holes 35 and 35 and screw holes formed in the crawler frames 10 and 10 (not shown). Bolts 38 are inserted into the two to fix them.
[0020]
The reason why the rear driven wheel 12 is detachable without being welded to the crawler frame 10 is that the driven wheel can be used by changing the left and right sides.
When changing the left and right, the height of the two screw holes with respect to the crawler frames 10 and 10 is changed. In general, when the crawler 8 is moved forward to travel on a wet field, the aircraft is in a front-up position as described above when traveling on a place called a soft field or a super wet field. Even in a wet field, where the cultivator is hard, the tractor is buried up to the surface of the cultivator, and stable running is performed in that state. In such a case, since the heel is high, the heel-crossing performance is better if the rear side is larger when the heel is crossed. If the rounding up is small, not only the traverse ability is bad, but also the rear driven wheel 12 may hit the ground during traveling and receive a big shock and cause damage.
[0021]
Therefore, the left and right driven wheels are changed according to the field conditions so that the height can be changed at the same time to improve the running adaptability of the crawler.
Further, not limited to this embodiment, the roller 13 is generally supported in a cantilever state and is inserted from one side (outside), but in that case, the rearmost roller 13d and the rear driven wheel 12 Can not wrap.
[0022]
However, in this embodiment, since the rear driven wheel 12 is detachable, all the rollers 13 may be inserted and attached from one side, and then the rear driven wheel 12 may be attached to the crawler frames 10 and 10, and both are wrapped. And can be supported.
[0023]
By wrapping, the distance between the shaft centers of the rearmost wheel 13d and the rear driven wheel 12 is reduced, the overall length of the crawler 8 is also shortened, and the driven wheel 12 is higher than the wheel 13, so-called. There is a feature that the rear side round-up angle can be taken sufficiently to prevent the front-up posture of the crawler 8 in the wet paddy field.
[0024]
Furthermore, the crawler 8 itself is prevented from coming off by allowing the front end portion of the rear driven wheel 12 to enter and wrap in the recess 13s of the rearmost wheel 13d. Further, since the rear driven wheel 12 is relatively high, it is easy to move backward, and when a work machine such as a rotary tiller mounted on the rear part of the machine is lowered and grounded, the rotating tillage claws and the like are crawled. 8Easy to enter the lower end of the rear part, the work machine can be placed close to the machine, and the center of gravity when the work machine is mounted is forward and the rotary tilling work is stable. Reference numeral 36 denotes a pivot pin that supports the rear driven wheel 12.
[0025]
Further, in this embodiment, since the flat plates 17 and 17 supporting the lower surfaces of the rear axle cases 18 and 18 are inclined forward and downward, the downward load from the rear axle cases 18 and 18 is not directly applied to the vertical frame 15, and this flat plate Compared with the case where 17 and 17 are leveled, the load application point moves slightly forward, and the distance to the center of gravity of the aircraft is shortened, so the moment to rotate the crawler 8 forward is reduced. be able to.
[0026]
3 and 4, reference numeral 40 denotes a reinforcing pipe that obliquely connects the rear vertical frame 15 and the rear portion of the crawler frame 10. Reference numeral 41 denotes a detachment prevention rod for preventing the oscillating rolling wheels 13a and 13b from coming off the crawler 8, and reference numeral 42 denotes a detachment prevention rod for preventing the crawler 8 from coming off the front wheel 13c. These detachment prevention rods 41 and 42 are configured to be detachable so that they can be easily replaced when worn. The foremost wheel 13c is fastened with a bolt 44 to a frame portion 10a integrated with the crawler frame 10, and the other side. The detachment prevention rod 41 is fastened with bolts 45 to the swing arms 26 and 26.
[0027]
Further, the front driven wheels 11 and 11 are configured to be able to move back and forth. Specifically, square pipes 47 and 47 are fixed on the crawler frames 10 and 10, and the driven pipes 11 and 47 are driven. The support bosses 48, 48 supporting 11 are fitted and inserted, and the bosses 51, 51 integral with the driven wheels 11, 11 are configured to move in the front-rear direction by turning the head of the screw rod 50.
[0028]
When the loose crawler 8 is stretched or the crawler 8 itself is replaced, the threaded rod 50 is rotated to change the protruding length. In the bosses 51, 51, pivot pins 53, 53 are provided, and the front driven wheels 11, 11 are supported by the pivot pins 53, 53. In FIG. 1, reference numeral 54 is a fender, 55 is a clutch pedal, 56 is a seat, 57 is a safety frame, 58 is a lift arm, and 59 is a 2P hitch. In FIG. 2, reference numeral 61 is a brake pedal, 62 is a step for getting on and off, 63 is a control unit for rolling control, 64 is a hydraulic operation lever, 65 is a tilling control lever, 66 is a main transmission lever, 67 is a PTO lever, and 68 is a secondary lever. A transmission lever 69 is a blinker.
[0029]
The rolling control operating unit 63 adjusts the right / left tilting posture of a working machine such as a rotary tiller mounted on the rear part of the agricultural tractor 1, and controls the working machine to a horizontal posture at all times. Operate when tilted.
The hydraulic lever 64 raises and lowers the work implement. When the hydraulic lever 64 is pulled up, hydraulic oil flows into a hydraulic cylinder, which will be described later, and the lift arm 59 rotates in the upward direction.
[0030]
The plowing depth lever 65 regulates the depth of plowing during the so-called depth operation. When the plowing depth lever 65 is raised and moved to the “shallow plowing depth” side, the rear cover of the rotary plowing device (not shown) is attached. Even if it moves up slightly, the signal is fed back to the hydraulic lifting system, but conversely, if this plowing lever 65 is lowered and operated to the “deep” side, this will raise a considerable amount even if the rear cover is lifted during plowing work. Unless otherwise stated, there will be no signal to raise the implement unless it is considerably deeper.
[0031]
Next, the operation of the above example will be described.
When the agricultural tractor 1 is placed in the field and the machine is traveling, the rotational power of the drive sprockets 7 and 7 is transmitted to the crawler 8, and the machine is propelled by exerting a strong driving force. The front part of the crawler 8 tries to turn upward due to the reaction force of the ground as the aircraft advances, but the agricultural tractor 1 in this embodiment has a denser distribution toward the rear side of the rolling wheels 13. Since it is supported by the crawler frame 10, the load applied to one of the wheels is small and there is no fear that an excessive load will act on the rollers 13 to break it.
[0032]
In addition, when the front side of the crawler 8 is lifted, for example, when it crosses the heel, the front lower portion of the crawler 8 is slackened and the foremost wheel 13c is separated from the crawler 8, which may cause the wheel to come off. In the embodiment, the oscillating rollers 13a and 13b are provided at the intermediate portion, and the oscillating rollers 13a and 13b are urged by the spring 27 so that the front side is in the upward position. As a result, the wheel 13b is pressed downward, and as a result, the disengagement prevention rod 41 integrated with the swing arm 26 is also pressed downward, and the mountain shape formed at the center of the crawler 8 is formed. It is possible to prevent the crawler 8 from coming off by biting into the detachment prevention guide portion.
[0033]
Further, most of the rolling wheels 13 and the driven wheels 11 and 12 are buried in the mud during the wet field traveling, and particularly when turning, the rolling wheels 13 and the driven wheels 11 and 12 are large in the lateral direction. As a result, the mud tends to hit the outer surfaces of the track frames 10 and 10, but the track frames 10 and 10 have not only a small vertical width, but also between the track frames 10 and 10 and the main frame. Since the space portion A is formed, the mud pushing phenomenon due to the frame is eliminated, and there is no fear of the track frames 10 and 10 being damaged and deformed.
[0034]
Finally, the structure around the seat will be described with reference to FIGS.
As shown in FIG. 6, brackets 73 and 74 that are bent in an inverted U shape when viewed from the front are attached to the left and right folded portions 72 a and 72 a of the base 72 at the top of the rear mission case 4. A tilling lever 65 is supported by the right bracket 73 in the traveling direction, and a main transmission lever 66 is pivotally supported by the left bracket 74.
[0035]
The left and right brackets 73 and 74 are connected to each other by a plate-like front frame 75, and a cylindrical boss 78 that supports the rotating shaft 76 of the hydraulic lever 64 is fixed on the front frame 75. A pipe 79 covers the outer periphery of the rotating shaft 76. A cylindrical boss 80 provided on the rotation base of the hydraulic lever 64 is freely fitted on the outside of the rotation shaft 76. The boss 80 has a fan-shaped side surface and has an uneven groove 82 on the outer periphery. A positioning plate 81 is integrally fixed. The concave / convex groove 82 determines a lowered position, a neutral position, and a raised position of the hydraulic lever 64. Under normal conditions, the roller 83 enters the neutral position (the center position of the three grooves) to stop the movement of the hydraulic lever 64. The roller 83 is constantly urged in a direction to enter the grooves 82.
[0036]
When the hydraulic lever 64 is operated to the ascending side and the lift arm 59 rotates to the maximum ascending position, the hydraulic lever 64 is returned to the neutral position by the interlocking return means such as the rod 70 and stops at the intermediate position of the groove 82. This will be explained with reference to FIG. 8. When the hydraulic lever 64 is moved upward, the roller 83 enters the concave groove on the front side, but the rod 70 is pulled backward by the lift arm 59 and the plate 84 rotates around the fulcrum 86. Then, the positioning plate 81 is pushed back through the plate 88, and the roller 83 enters the concavo-convex groove 82 at the neutral position to stop the hydraulic lever 64 at the neutral position.
[0037]
Further, a pin 85 is fixed horizontally and horizontally inside the positioning plate 81, and this pin 85 is brought into contact with the locking plate 87 integral with the rotating shaft 76 from the front side.
On the other hand, a cam plate 89 is fixed to the inner end portion of the rotating shaft 76, and the cam plate 89 is configured to press the spool 92 of the lift valve 90 to raise the working machine.
[0038]
Accordingly, when the hydraulic lever 64 is rotated in the working machine ascending direction (clockwise in FIG. 7), the pin 85 fixed to the positioning plate 81 similarly rotates the locking plate 87 in the clockwise direction. The integral rotation shaft 76 is rotated clockwise, the cam plate 89 is rotated, and the spool 92 is pressed.
[0039]
When the spool 92 is pressed, the raising / lowering valve 90 is switched to the raising side to rotate the lift arm 59.
A single-acting hydraulic cylinder 94 for rotating the lift arm 59 is provided along the front-rear direction on the base 72, and its front end is attached to two frames 95, 95 on the base 72. It is attached with a pin 96.
[0040]
Reference numeral 97 denotes a horizontal control valve installed below the lifting valve 90. Two hoses 98, 98 extend from this and are connected to a double-acting rolling cylinder (not shown) to bring the working machine to the intended posture. maintain.
A turn control valve 99 and a pressure proportional valve 100 for turning the airframe are provided at the rear part of the lift valve 90 and the horizontal control valve 97, and a right or left turn control valve depending on the operation direction of the steering handle 56. 99 operates, and the clutch on the turning side (not shown) is operated at a pressure corresponding to the operation angle. Although a detailed description of the control method for the turning clutch has already been filed, the forward and reverse clutches are provided on the left and right rear axle cases 18 and 18, respectively. When the forward rotation clutch is connected to maintain straight running and the steering handle 56 is rotated in either the left or right direction, the pressure of the forward rotation clutch on the rotating side gradually decreases, and steering in that direction is performed. When the steering handle 56 is further rotated beyond the above, the reverse rotation clutch is engaged so that a spin turn is performed.
[0041]
As apparent from FIG. 7, two pins 103, 103 are fixed to the side of the locking plate 87, and one end of the inner wire 104 for controlling the tilling depth is attached to any one pin 103. The reason why the two pins 103 and 103 are provided is to switch the sensitivity, and only one pin 103 may be provided. The distal end portion of the outer wire 105 through which the inner wire 104 is inserted is supported integrally with the tilling depth lever 65 by an L-shaped plate 107 in plan view. Reference numeral 101 denotes a rotation axis of the tilling lever 65. When the plowing depth lever 65 is operated to the deep side, the outer wire 105 moves to the front side together with the plowing depth lever 65, and on the contrary, when the plowing depth lever 65 is rotated to the shallow side, the outer wire 105 moves rearward. When the plowing operation is started with the plowing depth set by the plowing depth lever 65, the rear cover of the rotary tiller picks up the unevenness of the ground and rotates up and down, and the vertical movement of the rear cover is transmitted to the inner wire 104.
[0042]
Accordingly, when the working depth is deepened during the operation and the rear cover is lifted by the soil, the inner wire 104 is pulled backward, the locking plate 87 is rotated backward (clockwise in FIGS. 7 and 8), and the rotary shaft 76 is rotated. Then, the spool 92 is pushed in sequentially through the cam plate 89, and the lifting valve 90 is switched to the raising side to raise the rotary tiller.
[0043]
【The invention's effect】
According to the first aspect of the present invention, the crawler 8 includes a drive sprocket 7 attached to the drive shaft 5 protruding from the transmission case 3, two front and rear driven wheels 11, 12 attached to the crawler frame 10, and a plurality of rolling wheels 13. In the mobile vehicle in which the crawler running part is formed by winding the main frame 14 along the front-rear direction separately from the crawler frame 10, the main frame 14 and the crawler frame 10 are provided in the vertical frame 15. Therefore, even if the mud adheres to the front and rear driven wheels 11, 12, and the rolling wheels 13 and accumulates on the crawler frame 10 during the work in the wetland, these mud is immediately outside the crawler frame 10. Smooth turning without the risk of bending the crawler frame 10 due to resistance from mud during turning It can wait. Further, since the load applied to the crawler frame 10 is received on the vehicle main body side via the main frame 14, deformation of the crawler frame 10 can be prevented.
[0044]
Also,When the crawler 8 moves forward in the field, the front part of the crawler 8 is lifted by a reaction force from the ground. In order to support this reaction force with a large number of wheels 13 and reduce the load sharing per roller, it is necessary to support the crawler 8 with a small interval between the wheels, so The interval between the oscillating roller 13b and the rearmost roller 13d is minimized, the interval between the oscillating rollers is set larger than that, and the interval between the front oscillating roller 13a and the frontmost roller 13c is oscillated. By setting it to be larger than the distance between the wheels, the load applied to the rear wheel is reduced, and the wheel is prevented from being damaged and the durability is improved.
[0045]
Also,Since the front end portion of the rear driven wheel 12 is inserted into the recessed portion 13s of the rear wheel 13d and overlapped, the distance between the axial centers of the rear wheel 13d and the rear driven wheel 12 is reduced. The total length of the crawler 8 is also shortened, and the driven wheel 12 is higher than the wheel 13d. Therefore, a sufficient angle for the rear side can be secured to prevent the crawler 8 from being lifted forward in the wet field.
[0046]
Also,A flat plate 17 is fixedly attached to the upper part of the rear vertical frame 15 in a forwardly lowered posture, the flat plate 17 is fixed by being pressed against the lower surface of the rear axle case 18, and the rear vertical frame 15 is connected to the flat plate 17. Therefore, the downward load from the rear axle case 18 is not directly applied to the vertical frame 15, and the load application point moves slightly forward compared to the case where the flat plate 17 is horizontal. In other words, since the distance to the center of gravity of the machine body is shortened, the moment to rotate the crawler 8 forward can be reduced.
[0047]
Claims2ThenThe front swinging roller 13a and the rear swinging roller 13b are supported by swinging arms 26, 26. The swinging centers of the swinging arms 26, 26 are the line segments connecting the centers of the respective rolling wheels in the horizontal state and the front and rear. Since it is comprised between the segment which connects the center of the driven wheels 11 and 12, the restoring property of the rocking wheels 13a and 13b is improved.
That is, if the swing center position of the swing arms 26, 26 is too high, the swing arms 26, 26 may be pushed by the mud, and the whole may turn. By doing as mentioned above, the return | restoration property of the rocking | swiveling arms 26 and 26 improves, and the followable | trackability with respect to the unevenness | corrugation of a field improves.
[Brief description of the drawings]
FIG. 1 is a side view of a tractor.
FIG. 2 is a plan view thereof.
FIG. 3 is an enlarged side view of a main part.
FIG. 4 is an enlarged plan view of a main part with a part cut away.
FIG. 5 is a plan view of a main part.
FIG. 6 is a front view of the main part.
FIG. 7 is a side view of the main part.
FIG. 8 is a side view of the main part.
[Explanation of symbols]
1 Agricultural tractor
2 Engine
3 Mission case
4    Rear mission case
5 Drive shaft
7 Drive sprocket
8 Crawler
10 Crawler frame
11 Follower wheel
12 Follower wheel
13 Rolling wheels
13a  Front swing wheel
13b  Rear swing wheel
13c  Front wheel
13d  The last wheel
13s  Concave part of the last wheel
14 Mainframe
15 Vertical frame
17    Flat plate
18    Rear axle case
26    Swing arm
40    Reinforcement pipe

Claims (2)

A drive sprocket (7) attached to the drive shaft (5) protruding from the rear mission case (4) connected to the rear part of the transmission case (3) , and two front and rear driven wheels (11) attached to the crawler frame (10) ), (12) and a plurality of rolling wheels (13)... In the agricultural tractor formed only by the crawler traveling portion by winding the crawler (8), separately from the crawler frame (10), the main frame along the front-rear direction (14) is provided at the lower part of the vehicle body, and the main frame (14) and the crawler frame (10) are connected by the front and rear longitudinal frames (15), (15) ,
The distance between the rear oscillating roller (13b) and the rearmost roller (13d) is minimized, and the interval between the oscillating rollers is larger than that. The front oscillating roller (13a) and the frontmost roller The distance between the wheel (13c) is larger than the distance between the oscillating wheels.
The rear wheel (12) and the rear wheel (13d) are partially overlapped with each other when the rear wheel (12) and the rear wheel (13d) are viewed from the side, with the center position of the rear wheel (13d) positioned behind the center position of the drive sprocket (7). The rear end of the rear driven wheel (12) is inserted into the recess (13s) of the rearmost wheel (13d) and overlapped.
A rear axle case (18) is formed on the rear transmission case (4), and a flat plate (17) is fixedly attached to the upper portion of the rear vertical frame (15) in a forwardly lowered posture, and the flat plate (17) is provided on the rear axle. A reinforcement pipe (40) is provided that is fixed by pressing against the lower surface of the case (18) and obliquely connects the rear vertical frame (15) and the rear part of the crawler frame (10). An agricultural tractor characterized in that a frame (15) is connected to the flat plate (17) to receive the load of the airframe . The front swinging wheel (13a) and the rear swinging wheel (13b) are supported by swinging arms (26) and (26), and the swinging centers of the swinging arms (26) and (26) are horizontal. 2. The moving vehicle according to claim 1, wherein the moving vehicle is smaller than the line segment connecting the centers of the respective rolling wheels in the state and the line segments connecting the centers of the front and rear driven wheels (11), (12). .

Images