JP3531853B2 - Tractor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tractor which is switchable between a wheel type and a crawler type and can be used in a wide range of paddy fields, upland fields and dairy farming, and has improved versatility.

[0002]

2. Description of the Related Art Tractors, particularly agricultural tractors, can be roughly classified into a wheel type (wheel type) and a crawler type (crawler type) according to traveling devices. The wheel type is a four-wheel drive type with two axes and four wheels, and a rear type. It can be subdivided into a wheel drive type, a front wheel drive type, and the like, and the crawler type can be subdivided into a full crawler type and a semi-crawler type (see pages 257 to 259 of the new edition agricultural machinery handbook). The wheel-type tractor can be used in a wide range of fields such as tilling, sowing, tilling, weeding, harvesting, and transportation by equipping it with a three-point link, a PTO shaft, and a hydraulic control device. It is regarded as a motor vehicle and is the mainstream of agricultural mechanization.

Further, since the full crawler type tractor has a large ground contact area, the ground contact pressure is smaller than that of the wheel type tractor, it is possible to travel on rough terrain such as soft ground, and the weight is large and the adhesion coefficient is large. Suitable for heavy work that requires traction, for example, a so-called seasonal prompt-type special machine that is used exclusively for land preparation and land improvement by subsoilers for securing drainage in wetlands where wheel-type tractors cannot work. is there. On the other hand, the semi-crawler type tractor
It is an auxiliary device of a wheel type tractor in which the rear wheel is replaced and a crawler belt unit is mounted, and has an intermediate performance between the wheel type and the full crawler type on a soft ground.

[0004]

Although the wheel-type tractor is highly mobile and suitable for a wide range of work, due to the bad weather in autumn and the influence of snow in early spring, the cultivating time (called spring cultivation, crop growth, If harvesting is taken into consideration, the period is almost constant in spring, and if the field is not dry, there is a problem that the wheeled tractor is virtually impossible to enter the field and it becomes impossible to cultivate. It was On the other hand, the full crawler type tractor is effective in the above-mentioned situation, that is, in bad conditions and in strong wetlands in various places, but lacks mobility and is a dedicated machine, so it can be used only for limited work. It cannot be applied, and if it is used for harvesting work in dry fields, the field will be overwhelmed.In the end, both wheel-type tractors and full-crawler-type tractors must be prepared. The problem is that it will be enormous.

For this reason, the semi-crawler type tractor is disclosed in, for example, Japanese Patent Laid-Open No. 4-25778 (1 of the prior art), Japanese Utility Model Publication 6-5974 and Japanese Utility Model Publication 63-7048.
Japanese Patent Laid-Open No. 8 (conventional example 2) and the like have been proposed. But,
In Conventional Example 1, a rolling wheel is provided behind the rear wheel, and a crawler belt (endless rolling body) is hung across both wheels, and the traveling device (rolling wheel) protrudes largely behind the tractor body. As a result, not only does it hinder the installation of work implements that use three-point links, and the wheelbase is too large, resulting in poor turning performance, but there is also pitching of the vehicle body when driving over rough terrain. In this case, not only the work posture collapses and the driver is easily tired, but also the relative posture with respect to the work machine tractor body collapses, and it is difficult to expect stable work posture and improvement in finishing accuracy.

In the conventional example 2, since the semi-crawler is swingably mounted, there is some flexibility in the work in the uneven field, but it is applied to a special machine such as a combine harvester. However, it cannot be used to replace the rear wheel of the wheel-type tractor at all, and there is a problem in that it lacks mobility and versatility. Further, when the rear wheels are changed to semi-crawlers, there is a problem that the endless running body of the crawler easily comes off from the starting rotary body and so on, which is so-called derailing. Therefore, the present invention makes the wheel specifications and the crawler specifications compatible by mounting the rear axle-driven semi-crawler on the basis of the wheel-type tractor,
Moreover, the semi-crawler provides a tractor which swings the semi-crawler to reduce pitching, excels in maneuverability and running performance, and prevents the front wheels from rising.

[0007]

DISCLOSURE OF THE INVENTION The present invention has left and right front wheels that can be steered by operating a steering wheel, and has left and right rear axles that are driven by a transmission and a rear wheel differential device incorporated in a tractor body. , The left and right rear wheels and the left and right semi-crawlers are freely replaceable, and the left and right semi-crawlers are the rotary drive unit attached to the rear axle and the front and rear rotary followers mounted on the track frame. The truck frame is provided with a driving body and an endless rotating body mounted on front and rear rotary followers, and the track frame is supported by a tractor body so as to be vertically swingable via a swing support shaft. The above-mentioned problem is solved by providing the swing limiting means for limiting the swing range in the vertical direction.

That is, when the wheel type is ahead of the cultivating time due to bad weather in autumn and the influence of snow in the early spring, so-called spring tillage can be performed by replacing the left and right rear wheels with the left and right semi-crawlers. Since the semi-crawler can swing up and down at this time, the pitching phenomenon of the tractor is small, and therefore the fatigue of the operator (driver) is not excessive and the working posture is stable. The work accuracy can be secured. Further, since it is a semi-crawler, the ground contact pressure is lower than that of the rear wheels, and moreover, the traction force can be increased, and even when working on a sloping ground, skidding is reduced and work can be performed along contour lines.

Furthermore, for example, it is also possible to form a drainage ditch in a field using a subcoiler or the like by using a semi-crawler type due to bad weather such as autumn. In addition, when maneuverability is required, such as in the case of pest control work in dry fields, harvesting work, etc., the work can be done by changing to the rear wheels instead of the semi-crawler. By using one tractor, the rear wheels and the semi-crawler can be changed to reduce the burden of agricultural management.

Further, since the swinging range of the semi-crawler is limited, it is possible to prevent the left and right front wheels from rising while the left and right semi-crawlers are traveling on snowy roads, super wetlands, rough terrain, etc. It will be possible. Further, the rocking restricting means is set such that the upper rocking is larger than the lower rocking on the basis of the time when the ground contact portion of the endless rotating body hooked on the front and rear rotary followers is on the horizontal plane. The swing limiting means has a box-shaped bracket attached to the track frame and having a vertical guide portion, and a roller that is inserted in the guide portion and rolls, and is attached to the tractor body. It is preferable that the fixed bracket and the fixed bracket are provided.

Furthermore, in order to adjust the tension and relaxation of the endless rotating body that is hung on the rotary drive body and the front rotation driven body due to the swing of the track frame, the front rotation driven body is provided with a tension adjusting means. As a result, there is no derailment of the endless rolling body, lateral blurring, etc. in both forward and backward traveling with the left and right semi-crawlers, and it is possible to reliably circulate and exert a large traction force. The waviness of the endless revolving body during running is reduced. In addition, left and right front attachments attached to the left and right elevations of the tractor body and detachable, and left and right rear attachments attached to the lower surface of the rear axle case protruding from the tractor body and detachable Since the track frame of the semi-crawler is swingably mounted on the tractor vehicle body through the mounting frame framed in a rectangular shape in plan view, even if the left and right semi-crawler vehicles are mounted on the tractor vehicle body, the load on the tractor vehicle body is reduced. Is reduced, and the mounting is easy and quick.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1 showing an overall side view in which the rear wheels are replaced with semi-crawlers, FIG. 2 showing a rear view, and FIG. 3 showing a configuration of a traveling transmission system, a tractor 1 according to the present invention is operated by operating a steering wheel 2. Driven by a rear-wheel traveling transmission system 7 that includes steerable left and right front wheels 3 and includes a transmission 5 that is built in a tractor vehicle body 4 and that is capable of changing the traveling speed in multiple stages and a rear-wheel differential device 6. The left and right rear axles 8 are provided with left and right rear wheels 9 and left and right semi-crawlers 10 in a freely replaceable manner.

The left and right semi-crawlers 10 are mounted on the rear axle 8.
Of the rotary drive body 11 attached to the shaft end and the front and rear rotary followers 13 and 14 mounted on the track frame 12 and the rotary drive body 11 and the front and rear rotary followers 13 and 14 respectively. The track frame 12 is supported by the tractor body 4 so as to be swingable in the vertical direction via a swing support shaft 16. A driver's seat 17 is provided behind the steering wheel 2 to form a steering device 18, which is surrounded by a cabin 19, which is mounted on the tractor body 4.

The cabin 19 has a box-shaped skeleton body 20, a windshield element 21 attached to the front surface of the skeleton body 20, a rear glass element 22 attached to the rear surface of the skeleton body 20, The side door element 23 is attached to the skeleton body 20 on both the left and right sides of the driver's seat 17, and the left and right opening and closing doors 25 are opened and closed around the vertical axis by the hinge means 24 in front of the side glass element 23. 25 together with the boarding / alighting step 30 substantially form part of the boarding / alighting means for the control device 18. The tractor vehicle body 4 is mainly composed of an engine 26 and a mission case 27 connected to the rear surface of the engine 26. The engine 26 is covered with a hood 28, and the mission case 27 includes a main clutch element 29. A traveling transmission system 7 that receives engine power through the main clutch element 29, a PTO transmission system (not shown), and the like are incorporated.

The traveling transmission 5 includes a main transmission 31 that can change the traveling speed in a plurality of stages, an auxiliary transmission 33 that can change the traveling speed to high or low by a lever 32, and a shuttle transmission or creep (not shown). Equipped with a gearbox,
It is interlocked with the rear wheel differential device 6 via a differential drive shaft 34 exemplified by a bevel pinion shaft. The left and right output shafts 6A of the rear wheel differential device 6 are interlocked with the left and right rear axles 8 via a brake device 35 and a speed reducer 36, and the rear axle 8 is attached to a rear axle case 37 as shown in FIG. The left and right rear axle cases 37 are inserted and supported, and the left and right rear wheel fenders 38 and the rear portion of the cabin 19 are supported.

As shown in FIGS. 4-7, the semi-crawler 10
Is mounted on the tractor vehicle body 4 via a mounting frame 39 mounted on the lower surface of the tractor vehicle body 4 and framed in a rectangular shape in plan view. The mounting frame 39 is attached to the left and right front attachments 40 attached to the left and right standing surfaces of the tractor vehicle body 4 and detachable by bolts, and the lower surface of the rear axle case 37 protruding from the tractor vehicle body 4 and attached to the bolts. Has left and right rear mounting tools 41 that are detachable by
The mounting frame 39 is fixed to the lower abdomen of the tractor body 4 with bolts or the like via the rear mounting members 40 and 41.

As described above, the semi-crawler 10 is not directly supported on the tractor vehicle body 4 but is supported via the mounting frame 39. The transmission case 27 and the like constituting the tractor vehicle body 4 are usually made of cast metal. There is a risk of cracking due to repeated external forces, etc.
It is supported through a mounting frame 39 made of a steel rectangular frame. The rear mounting tool 41 of the mounting frame 39 is provided with a swing support shaft 16 protruding in the left-right direction, while the track frame 12 is configured such that the left and right swing support shafts 16 are rotatable about their axes. A bearing cylinder 42 for receiving is provided, and the track frame 12 of the semi-crawler 10 is swingably attached to the tractor body 4 via the mounting frame 39 by the swing support shaft 16 and the bearing cylinder 42.

The semi-crawler 10 is a tractor body 4
Since it suffices that the swing support shaft 16 is supported by the track frame 12 and the bearing sleeve 42 is supported by the tractor vehicle body 4.
It may be provided on the side. Further, the position of the swing support shaft 16 is free if its axis is parallel to the rear axle 8, but in this embodiment, as shown in FIG. 1, a vertical line V- passing through the axis of the rear axle 8 Since the swing support shaft 16 is located below the V, the swing amplitude when the swing support shaft 16 approaches the ground contact side and thus the swing amplitude becomes small and the pitching phenomenon occurs. It can be effectively suppressed, which is advantageous.

Rotational driving body 11 in the semi-crawler 10
Although a drum type, a roller type, a sprocket type or the like can be selected, the example is a sprocket type and is attached to the shaft end flange 8A of the rear axle 8 with a plurality of bolts or the like as shown in FIG. The rotary drive body 11 is integrally provided with a support shaft 43 projecting outward at its axis, and a bearing portion 44A of a support arm 44 is externally fitted to the outer end of the support shaft 43, and a lower portion of the support arm 44 is provided. Are supported by a bracket 45 protruding from the track frame 12 via another swing support shaft 47.

The other swing support shaft 47 is located on an extension of the above-mentioned swing support shaft 16, and the track frame 12 has a common shaft center at two locations inside and outside of which the rotary drive body 11 is sandwiched. Further, the swinging support shafts 16 and 47 support the swinging support shafts and 47 to reliably prevent lateral shake. The support arm 44
Includes a rotary drive 11 and a track frame 12
A lock means 48 for locking relative swinging with respect to is provided. The lock means 48 includes a lock hole 48A formed in the support arm 44 and a receiving hole 48 formed in the bracket 45.
B and a lock pin 48C which is inserted into and removed from both holes 48A and 48B when they are aligned with each other, and is formed below the swing support shaft 47 in the illustrated example, but is formed above. Alternatively, a plurality of lock holes 48A and 48B may be formed and a plurality of lock pins 48C may be inserted and removed, and the lock pins may be bolts and nuts.

Therefore, when the semi-crawler 10 is changed to the rear axle 8, the rocking is restricted by the locking means 48 and the rotation is fixed to the rear axle 8, and the rocking support shaft is attached. 16 positioning is easy,
After replacing the semi-crawler 10, the locking means 4
8 is unlocked so that it can swing freely. In FIG. 10, reference numeral 49 denotes a retaining collar, which is fitted to the bearing portion 44A and fixed to the shaft end surface of the support shaft 43 with a bolt 50. Further, although the bearing portion 44A is shown as a ball bearing, it may be another bearing such as a pillow block bearing.

The left and right semi-crawlers 10 that have been replaced by the rear axle 8 are so-called rice balls in a side view as shown in FIGS. 1 and 8, and the vertical line V-V passing through the axis of the rear axle 8 is used as a reference. The front and rear ground contact lengths L1 and L2 are different from each other, and in the figure, the front ground contact length L1 is large and the rear ground contact length L2 is small, so that the semi-crawler 10 is prevented from being largely projected rearward from the tractor vehicle body 4. The work equipment (rotary, plow, subsoiler, broadcaster, etc.) can be easily mounted through a mounting means such as a three-point link provided at the rear of the tractor body 4, and a sufficient grounding length is secured. It prevents the skids from slipping on slopes, and promises great traction.

The endless revolving body 15 in the left and right semi-crawlers 10 is an elastic crawler (rubber crawler) having a row of grounding lugs 15A on its outer circumference and a row of guide protrusions 15B on its inner circumference. The front rotation driven body 13 is positioned in the vicinity of the boarding / alighting step 30 so that the front rotation driven body 13 and the front rotation driven body 13 are hooked in a downward slope. By adopting such a configuration, the endless revolving body 15 can be used as a boarding / alighting assistance step, and even if the door 25 is opened and closed centering on the hinge means 24, the endless revolving body 15 becomes an obstacle. Also, the axial distance (the distance between the front wheel 3 and the rear wheel 9) is almost the same as that of the semi-crawler type tractor 1 or the wheel type tractor, and even the semi crawler type tractor has a small turning performance. Can be done.

As shown in FIG. 1, the tractor 1 moves forward when the rotary drive member 11 is rotationally driven in the direction of arrow F, and the tractor 1 moves backward when it is rotationally driven in the direction opposite to the arrow F. However, the endless rotating body 15 in which the rotation driving body 11 on the slack side during forward traveling is hooked on the front rotation driven body 13 adjusts tension and relaxation accompanying the swing of the track frame 12, The body 13 is provided with a tension adjusting means 51. This tension adjusting means 51 is shown in FIG.
As shown in FIG.
Is automatically adjusted by a coil spring 53, a tension cylinder 54, etc.
Is equipped with.

A plurality of guide wheels 55, four guide wheels 55 in the figure, are arranged in a row on the track frame 12, and the endless rotating body 15 in which the rotary drive body 11 and the front rotary driven body 13 are hooked.
There is provided guide means (crawler support) 56 which comes into contact with the inner peripheral surface of the above and prevents the slack. The guide means 56 is detachably provided on the tension cylinder 54, and as shown in FIG. 7, the guide portion 56A at the tip thereof is bifurcated, and is made of an elastic band plate such as SS330. Has been done.

The left and right semi-crawlers 10 have a swing support shaft 16
The truck frame 12 swings vertically with the fulcrum as a fulcrum to absorb the pitching phenomenon of the tractor vehicle body 4 in uneven fields, rough terrain, snowy roads, etc.
A swing limiting means 57 for limiting the vertical swing range of the track frame 12 is provided. As shown in FIGS. 4, 7 and 9, the swing limiting means 57 is attached to the track frame 12 and has a vertical guide portion 58.
A box-shaped bracket 58 having A, and a fixed bracket 59 having a roller 59A inserted into the guide portion 58A and rolling and attached to the tractor body 4 via a mounting frame 39. And the fixing bracket 5
9 is a receiving bracket 5 fixed to the mounting frame 39
It is detachably attached to 9A with bolts.

Further, the rocking restricting means 57 has a larger upward rocking than a downward rocking when the ground contact portion of the endless running body 15 mounted on the front and rear rotary followers 13 and 14 is on a horizontal plane. Has been set, and in the example shown, the front side is 8 ° upwards,
It is supposed to incline 5 ° downward. It should be noted that the swing limiting means 57 includes a box-shaped bracket 58 and a mounting frame 3 for mounting the box-shaped bracket 58.
9, a fixed bracket 59 may be provided on the track frame 12, and a sliding shoe type may be used instead of the roller 59A.

Referring to FIG. 3, a front wheel traveling transmission system 60 is branched from the rear wheel differential drive shaft 34, and the transmission system 60 is branched.
The left and right front wheels 3 can be driven via a front wheel differential device 61 provided in the. The front wheel traveling transmission system 60 has a shift gear 62 provided on the rear wheel differential drive shaft 34, and is selectively engageable with a gear 63A on the first transmission shaft 63. Gears 64A and 6 are provided on the extension of the axis of the first transmission shaft 63.
The second transmission shaft 64 having 4B is mounted on the
Between the two transmission shafts 63 and 64, there is provided a clutch means 65 for switching the front wheel 3 between a driving state and a non-driving state. When changing to the semi-crawler 10 and traveling straight ahead, the clutch means 65 is disengaged. 3 is in a non-driving state (so-called rear wheel driving, the front wheels are idling), and when turning, the clutch means 65 is brought into contact with the front wheels 3 in a driving state (4
It is equipped with a manual operation means for changing to a wheel drive state.

This manual operation means is provided near the driver's seat, and when the clutch means 65 is the shift gear shown in the drawing, it is a shift operation lever and the clutch means 65.
Is a hydraulic clutch, it is an operation lever of an electromagnetic control valve for controlling the on / off of the clutch. Front wheel running conduction system 60
A traveling transmission body 66 is provided between the second transmission shaft 64 and the front wheel differential drive shaft 61A to make the peripheral speed of the rotary drive body 11 of the semi-crawler 10 and the peripheral speed of the front wheels 3 substantially constant. There is.

That is, when the left and right rear wheels 9 are replaced by the left and right semi-crawler 10, the diameter of the rotary drive body 11 becomes approximately half the diameter of the rear wheels 9, and the rear wheel traveling transmission system 7 is used as it is. Then, the peripheral speed of the rotary driving body 11 is approximately 1/2 times (approximately half) that of the rear wheel 9, and in this state, the front wheel 3
When the vehicle is driven, the front wheels 3 will wear out early.
Therefore, when the rear wheels 9 are replaced with the semi-crawler 10 using the rear wheel traveling system 7 as they are, the clutch means 65 provided in the front wheel traveling system 60 is disengaged to put the front wheels 3 into a non-driving state (idling). Alternatively, the traveling transmission 66 is incorporated to make the peripheral speeds of the rotary drive 11 and the front wheels 3 substantially constant.

In the embodiment shown in FIG. 3, the first hydraulic clutch 67 is provided on the front wheel differential drive shaft 61A or coaxially therewith.
And a second hydraulic clutch 68 are provided side by side in the front-rear direction, and the gear 67A of the first hydraulic clutch 67 is a first gear on the second transmission shaft 64.
The gear 68A of the second hydraulic clutch 68 meshes with the gear 64A of the second gear 64B on the second transmission shaft 64. At this time, the gear ratio of the gears 64A and 67A is the rotation drive body 11 of the semi-crawler and the front wheel. The gear ratio of the gears 64B and 68A is set to the same speed as the rear wheels 9 and the front wheels 3 or the gear ratio for increasing the speed of the front wheels 3. .

Therefore, when the shoes are changed to the semi-crawler 10, the first hydraulic clutch 6 of the speed reducers 64A and 67A is replaced.
When 7 is turned on, the semi-crawler and the front wheels are driven at a substantially constant speed. The first and second hydraulic clutches 67, 68
Since the front wheels 3 are not driven by disengaging both of them, the clutches 67 and 68 also serve as clutch means for switching between four-wheel drive and rear-wheel drive. 11 to 13 show a second embodiment of the traveling transmission body 66 which makes the peripheral speeds of the semi-crawler 10 and the front wheels 3 substantially constant. The hydraulic transmission is provided on the transmission shaft 64 of the front wheel traveling transmission system 60 and the differential drive shaft 61A. Type DT clutch (4 wheel drive on / off clutch) 69 and hydraulic double speed clutch (front wheel rotates about 1.6 times faster than rear wheel) 7
0 is provided side by side in the front and rear, and a double speed shaft having gears 71A and 71B that engage with a gear 70A that can freely rotate on the transmission shaft 64 and a gear 61B that is fixed to the differential drive shaft 61A is provided below the clutch. 71 is attached to the cassette case 72 which is detachably attached to the lower abdomen of the tractor vehicle body 4, and
Transmission shaft 66A for traveling transmission body 66 coaxial with 1
Is mounted on the cassette case 72.

Further, an input gear 64A for the traveling transmission body 66 is provided on the transmission shaft 64, and a gear 66B meshing with the input gear 64A is provided on the transmission shaft 66A. The transmission shaft 66A and the double speed shaft 71 are provided. Can be opened and closed by clutch means 66C shown by a shifter. In the second embodiment, when the rear wheels 9 are replaced by the semi-crawler 10, the clutch means 66C is turned on (contacted) and the gear 6 is turned on.
4A, 66B, the double speed shaft 71, and gears 71B, 61B to the front wheel diff drive shaft 61A so that the peripheral speeds of the rotary drive body 11 and the front wheel 3 are substantially the same. The traveling transmission body 66 is decelerating.

In the second embodiment, when the rear wheel 9 is attached to the rear axle 8, the operation is performed as shown in FIG. That is, when the turning angle of the front wheels 3 becomes about 34 ° or more by the operation of the steering wheel, the turning angle detection switch 73 attached on the left side of the front wheel case support is turned on,
The DT / double speed solenoid valve 74 is actuated to the double speed side to switch the double speed clutch 70 to "on". This causes the front wheels to rotate about 1.6 times faster than the rear wheels. The DT / double speed changeover switch 75 is a switch for changing over the type of power transmission to the front wheels, and is "DT (4WD = 4 wheel drive) / OFF",
You can switch between "DT / ON" and "double speed".
To activate a double speed turn, press this switch
Just set it to the position. When set to "DT ON" or "OFF", the solenoid valve works to operate the DT hydraulic clutch 69 integrated with the double speed hydraulic clutch 70 to switch ON / OFF of four-wheel drive.

FIGS. 14 and 15 show a third embodiment of the traveling transmission body 66, in which the front wheel differential drive shaft (or the front wheel propulsion shaft which is interlocked therewith) is constructed as the first and second shafts 76, 77. A shift gear 78 that connects and disconnects the first and second shafts 76 and 77 is slidably provided on the first shaft 76 by a spline or the like.
Gear 80 meshing with gears 78, 79 on shafts 76, 77
A transmission shaft 80 having A and 80B is incorporated in a case 81, and when the semi-crawler 10 is replaced with respect to the rear wheel 9, the shift gear 78 is disengaged and the gears 78, 8
By decelerating the front wheel differential 61 via 0A, 80B, and 79, the peripheral speeds of the rotary drive body 11 of the semi-crawler 10 and the front wheel 3 are made substantially constant, and when the rear wheel 9 is mounted, By the shift gear 78, the first and second shafts 76, 77
Is directly connected.

In the third embodiment, the double speed turn shown in FIG. 12 and the like can be provided as shown in FIG. FIG. 16 shows a fourth embodiment of the traveling transmission body 66, in which the rear wheel traveling transmission system 7 is provided with the rotary drive body 11 of the semi-crawler 10 so as to be switchable to increase the speed. In FIG. 16, the left and right rear axles 8 are divided into first shafts 82 and 83, and the two shafts 82 and 83 can be joined and separated via a first hydraulic clutch 84 that is connected and disconnected by a valve 84A. The second hydraulic clutch 86, which is connected / disconnected by the valve 86A, is incorporated on the accelerating auxiliary shaft 85, and the gear 82 of the first and second shafts 82 and 83 is installed.
Gears 85A and 85B that engage with A and 83A, respectively, are provided in the auxiliary groove 85.

In the fourth embodiment, when the rear wheel 9 is replaced with the semi-crawler 10, the first hydraulic clutch 8 is used.
4 is disengaged and the second hydraulic clutch 86 is brought into contact to drive the left and right rear axles, that is, the second shaft 83, through the gears 82A, 85A, 85B, and 83A to accelerate the rotary drive unit 11. The peripheral speeds of the front wheels 3 and the front wheels 3 are substantially constant. On the other hand, when the rear wheels 9 are mounted, the second hydraulic clutch 86 is disengaged and the first hydraulic clutch 84 is brought into contact with the first and second shafts. 82 and 83 are directly connected. It is desirable that the traveling transmission body 66 of the fourth embodiment be detachably attached to either the upper or lower side of the rear axle case 37.

Further, referring to FIG. 3 and FIGS.
3, a detection switch (detection device) 73 for detecting the steering angle of the left and right front wheels 3 and a hydraulic brake device 35 for controlling the left and right semi-crawlers 10 simultaneously and independently are provided. When the switch 73 detects that the steering angle of the front wheels 3 has been operated to a predetermined angle or more, a controller (control device) 87 is provided which independently brakes the brake device 35 of the semi-crawler 10 on the inside of the turn by the detection signal. Therefore, even in the case of the semi-crawler tractor, the small turning performance is improved, and it is desirable to switch the left and right front wheels 3 to the speed-increasing drive during the turning traveling.

That is, the tractor according to the present invention is provided with the left and right front wheels that can be steered by operating the steering wheel and can be driven by the front wheel drive transmission system. The left and right rear axles driven by the rear wheel traveling transmission system are equipped with the left and right rear wheels and the left and right semi-crawlers in a freely replaceable manner, and when the semi-crawlers are replaced, the peripheral speed of the rotary drive body in the semi-crawler is changed. And a traveling transmission that makes the peripheral speed of the front wheels substantially constant. The traveling transmission is provided in the front-wheel traveling transmission system and is capable of switching the rotational drive of the front wheels to deceleration. In this case, the traveling transmission body is a reduction gear device that is provided in the rear wheel traveling transmission system and is capable of switching the rotational drive of the rotational drive body in the semi-crawler to increase speed.

Further, the front-wheel traveling transmission system is provided with clutch means for switching the front wheels between a driving state and a non-driving state. When the vehicle is changed to a semi-crawler and the vehicle travels straight, the clutch means is disengaged to bring the front wheels into a non-driving state. A steering angle detecting device for detecting steering angles of the left and right front wheels, which is provided with a clutch operating means for bringing the front wheels into a driving state by bringing the clutch means into contact when turning. A pair of braking devices for independently braking the left and right semi-crawlers, and when the steering angle detecting device detects that the steering angle of the front wheels has been operated to a predetermined angle or more, the braking device for the semi-crawler on the inside of the turn. It is desirable to switch the left and right front wheels to speed-up drive when turning, and the traveling transmission is incorporated as a detachable unit. Rukoto is desirable.

[0041]

As described above in detail, in the tractor of the present invention, the left and right semi-crawlers whose rear wheels have been replaced are not swingably fixed to the tractor vehicle body but their track frames are swingably supported. The semi-crawler type tractor that is running is less likely to cause a pitching phenomenon, has a low ground contact pressure, and can improve the wetland performance while stabilizing the work posture and improving the finishing accuracy. Furthermore, the swing range of the semi-crawler is limited in the condition that the upward swing is larger than the downward swing, so it is possible to reliably prevent the front wheels from rising while running over snowy roads, sloping ground, rough terrain, etc. And stable driving is possible.

[Brief description of drawings]

FIG. 1 is a side view of a semi-crawler type tractor.

FIG. 2 is a rear view of the semi-crawler type tractor.

FIG. 3 is an overall configuration diagram of a traveling transmission system.

FIG. 4 is an exploded perspective view of left and right semi-crawlers.

FIG. 5 is a plan view of the left and right semi-crawlers.

FIG. 6 is an elevation view taken along the line AA of FIG.

7 is an elevation view taken along the line BB of FIG.

FIG. 8 is a side view of the semi-crawler.

FIG. 9 is a perspective view of rocking restricting means.

FIG. 10 is an enlarged cross-sectional view of a swing support shaft.

FIG. 11 is an overall configuration diagram showing a second embodiment of a traveling transmission system.

FIG. 12 is a partially enlarged view of FIG.

FIG. 13 is a configuration diagram showing switching of DT / double speed turn and the like.

FIG. 14 is an overall configuration diagram showing a third embodiment of a traveling transmission system.

FIG. 15 is a partially enlarged view of FIG.

FIG. 16 is a rear view showing a fourth embodiment of the traveling transmission system.

[Explanation of symbols]

1 tractor 2 steering wheel 3 front wheels 4 tractor body 8 rear axle 9 rear wheels 10 semi crawler 11 rotary drive 12 track frames 13 Front rotation driven body 14 Rear rotation driven body 15 Endless running body 16 Swing support shaft

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsushi Fukowase 64 Ishizukita-machi, Sakai City, Osaka Prefecture Kubota Co., Ltd.Sakai Plant (72) Masayuki Sato 64, Ishizukita-machi, Sakai City, Osaka Prefecture Kubota Sakai Manufacturing Co., Ltd. In-house (56) Reference Japanese Unexamined Patent Publication No. 5-97055 (JP, A) Actually opened 63-70484 (JP, U) Actually opened 5-92076 (JP, U) US Patent 2467947 (US, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) B62D 55/02 B62D 55/084

Claims (3)

(57) [Claims] 1. Left and right rear wheels and left and right rear wheels, which are provided with left and right front wheels steerable by operating a steering wheel, are driven by a transmission and a rear wheel differential device incorporated in a tractor vehicle body. A semi-crawler is provided so as to be replaceable, and the left and right semi-crawlers are a rotation driving body attached to a rear axle, a mounting frame which is attached to and detachable from a rear axle case protruding from a tractor vehicle body, A track frame mounted on the tractor vehicle body via a mounting frame, front and rear rotary followers that are mounted on the track frame, the rotary drive body and front and rear rotary followers, and the rear axle of the rear axle. An endless revolving body whose front ground contact length is set to be larger than the rear ground contact length with respect to a vertical line passing through the axial center, and the track frame is on a vertical line passing through the axial center of the rear axle and
Swing limiting means, which is supported by the mounting frame so as to be swingable in the vertical direction via a swing support shaft located below the axle, limits the swing range of the track frame in the vertical direction on the front side of the rear axle. The upper swing is set to be larger than the lower swing on the basis of the time when the ground contact portion of the endless rotating body, which is disposed between the track frame and the mounting frame and hung on the front and rear rotary followers, is on the horizontal plane , The track frame has a common shaft inside and outside the rotary drive.
It is possible to swing up and down via a swinging support shaft
The bearing of the support arm is attached to the support shaft that is integrated with the rotary drive.
When fitted, the lower part of this support arm swings on the swing support shaft.
Freely supported by the support arm and the track frame
Locking means that can lock the relative swing of both
A tractor characterized by being provided . 2. The swing limiting means is a track frame or
Vertical guide part attached to one side of the mounting frame
Box bracket with and track frame or mounting
Proposal of the box-shaped bracket attached to the other side of the frame
Structured with a fixed bracket that is inserted inside to guide freely
Tractor according to claim 1, characterized in that it has been made. 3. The mounting frame is on the left side of the tractor body.
Left and right front fittings attached to the right side and removable
And attached to the lower surface of the rear axle case to be removable
The tractor according to claim 1 or 2, wherein the tractor has left and right rear attachments and is framed in a rectangular shape in a plan view .