JP2002127705A - Tractor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tractor capable of satisfactory tread adjustment while avoiding contact of crops with a gear case mounted onto an outer end of an axle case. SOLUTION: The gear case 11 is fitted to a horizontally outer end of the axle case 23 fitted to protrude horizontally outward. A wheel 5 is attached so that the gear case 11 is fitted into the inner circumferential side of the wheel 5, and the gear case 11 is detachably attached to the axle case 23 so that the extended axle case 42 can be placed between the axle case 23 and gear case 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a tractor.

[0002]

2. Description of the Related Art Generally, in a two-shaft, four-wheel tractor, a rear wheel is a drive wheel, and a vehicle body of the tractor is configured by directly connecting a transmission case such as an engine, a clutch housing, and a transmission case. A rear axle case is provided on both left and right sides of a rear portion of the vehicle body so as to protrude outward in the left-right direction. There is also a tractor that has a high vehicle ground clearance. In this tractor, the upper part of the gear case is attached and fixed to the left and right outer ends of the rear axle case, and from the lower part of the gear case, There is a structure in which the rear wheel is mounted on the rear wheel axle that protrudes outward to increase the vehicle body ground height. In this case, the power from the engine is transmitted to the transmission mechanism in the transmission case, Power is transmitted to the transmission shaft in the rear axle case via the wheel differential mechanism, and power is transmitted from the transmission shaft to the rear wheel axle via the gear transmission mechanism in the gear case to rotate the rear wheel. ing.

[0003]

In the tractor, the tractor is run over a ridge, and is used for transplanting, harvesting, and managing work of a crop. The gear case is located inward of the rear wheel in the left-right direction. If it is located, the gear case may interfere with the crop depending on the height of the crop. Therefore, a configuration in which the rear wheel is attached to the gear case such that the gear case enters the inner peripheral side of the rear wheel has been considered. Also, as a method of adjusting the tread of the rear wheel, there is a method of adjusting the tread of the rear wheel by turning the disk of the rear wheel upside down and mounting it on the rear wheel axle. By adopting this tread adjustment method for a structure that attaches the rear wheel to the gear case so that the gear case enters, when the tread is adjusted, the gear case is located more inward in the left and right direction than the rear wheel. As a result, the gear case may interfere with the crop.

Further, a gear transmission mechanism in the gear case includes a first gear provided on a transmission shaft to which power is transmitted from an output shaft of a rear wheel differential mechanism, and a second gear provided on the rear wheel shaft below the first gear. It is configured by meshing gears, but compared with a tractor that has a low body height above the ground, setting the output shaft of the rear wheel differential mechanism and the rear wheel axle to which the rear wheel is mounted to be approximately the same axis. ,
Since the rotation is reversed by the gear transmission mechanism, the output shaft of the rear wheel differential mechanism and the rear wheel axis rotate reversely, and the rotation direction of the output shaft of the rear wheel differential mechanism is changed to the tractor when the vehicle body clearance is low. A countermeasure is taken to rotate in the opposite direction.

For example, a large bevel gear provided in a rear wheel differential mechanism and meshing with a bevel pinion is mounted on the rear wheel differential mechanism in a left-right reversed manner. For this reason, when the vehicle body ground height is high, it is impossible to make the structure of the tractor and the rear wheel differential mechanism identical when the vehicle body ground height is low, and to share parts. In the prior art,
To increase the ground clearance, the gear diameter must be increased, which increases costs.

Accordingly, an object of the present invention is to provide a tractor capable of solving the above-mentioned problems, and to achieve good tread adjustment while avoiding interference between a crop and a gear case provided on an outer end side of an axle case. It is intended to provide a tractor.

[0007]

A technical means for solving the problem in the present invention is that a gear case is provided on a laterally outer end of a laterally protruding axle case, and an inner periphery of a wheel is provided. A wheel is mounted on the gear case so that the gear case enters into the side, and a gear case is removably attachable to the axle case so that an extended axle case can be interposed between the axle case and the gear case. It is characterized by. Further, a gear transmission mechanism housed in a gear case is provided between a transmission shaft to which power is transmitted from an output shaft of a rear wheel differential mechanism and a rear wheel shaft to which a rear wheel is attached. A first gear interlockingly connected to the transmission shaft, a second gear provided below the first gear on the rear wheel axle, and an idler gear simultaneously meshing with the first gear and the second gear; May be arranged on the front side or the rear side of the first gear and the second gear.

Further, it is preferable that an idler gear is disposed in front of the first gear and the second gear, and three gears are disposed in a triangular arrangement in a gear case. Further, it is preferable that the transmission shaft and the support shaft supporting the first gear can be interlockedly connected via a coupling. Further, it is preferable that the auxiliary step provided between the front wheel and the rear wheel can be freely adjusted in the left-right position corresponding to the tread adjustment of the wheel. Further, it is preferable that the vehicle body and the auxiliary step are connected by a handrail.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. 5 to 9, reference numeral 21 denotes a biaxial four-wheel drive tractor including a pair of left and right front wheels 41 and a rear wheel 5.
Is mainly constructed by directly connecting an engine, a (clutch housing), a transmission case and the like. Fuel tanks 26 are mounted on left and right sides of the front and rear halfway of the vehicle body 22, a PTO shaft 29 is provided on a lower rear portion of the vehicle body 22, and a top link 30A and left and right lower A three-point link mechanism 30 including a link 30B is mounted.

A rear axle case (rear axle case) is provided on the left and right sides of the rear of the vehicle body (mission case) 22.
23 is provided in a laterally outwardly projecting shape from the side of the vehicle body 22. At the outer ends of the left and right rear axle cases 23, a gear case 11 for housing the gear transmission mechanism 7 is detachably attachable by bolts or the like, and protrudes outward from the lower part of the gear case 11 in the left-right direction. The rear wheel 5 is attached to the gear case 11 such that the disk 25 of the rear wheel 5 is bolted to the rear wheel shaft 6 and the gear case 11 enters the inner peripheral side of the rear wheel 6.

As shown in FIGS. 1 to 4, the gear case 11 is detachably mounted and fixed to the left and right outer ends of the rear axle case 23 or the left and right outer ends of the rear axle case 23. The inner case 11A is detachably attached to the extended axle case 42, and the outer case 11B is detachably attached and fixed to the inner case 11A by bolts or the like.
As shown in FIGS. 1 and 2, the extension axle case 42 attached and fixed to the left and right outer ends of the rear axle case 23 in the left and right directions, and FIGS. 3 and 4. As shown in FIG. 2, the mounting form can be changed to a form fixed to the outer end in the left-right direction of the rear axle case 23, whereby the tread of the left and right rear wheels 5
It is configured to be adjustable to different treads.

In the above-described vehicle, the rear wheel 5 is mounted on the gear case 11 so that the gear case 11 enters the inner peripheral side of the rear wheel 6.
To prevent the gear case 11 from interfering with the crop A located inside the rear wheel 5 and to increase the tread of the rear wheel 5.
Since 1 moves together with the rear wheel 5, even when the height of the crop A is high, the gear case 11 is prevented from interfering with the crop A. The tread can be adjusted to three or more types of treads by preparing a plurality of extension axle cases 42 having different lengths.

In the middle of the left and right rear axle case 23, a lower part of a support of a lops 27 is attached, and on the support of the lops 27, left and right rear wheel fenders 28 are mounted. A driver's seat 14 is arranged between the two. Next, a power transmission system from the engine to the rear wheel 5 will be described. As shown in FIGS. 2, 4, and 11, the rear of the transmission case forming the vehicle body 22 includes:
A bevel pinion 13 to which power from the engine is transmitted via a main clutch, a main transmission mechanism, an auxiliary transmission mechanism, and the like;
The rear wheel differential mechanism 2 to which power is transmitted from the bevel pinion 13 is disposed.

In the rear wheel differential mechanism 2, a large bevel gear 16 mounted on a differential case 15 meshes with a bevel pinion 13, and an output shaft 3 projects from the differential case 15 in the left-right direction. The large bevel gear 16 is mounted on the right side of the differential case 15 in rear view, and meshes with the right side of the bevel pinion 13. For example, the bevel pinion 13 rotates clockwise in rear view to move the output shaft 3 forward. It is rotated in the same direction as the rotation direction of the rear wheel 5 at the time.

A rear wheel brake mechanism 33 is provided between the output shaft 3 protruding left and right and the vehicle body 22.
, The left and right rear wheels 5 can be selectively or simultaneously braked. In the rear axle case 23, a transmission shaft 4 is rotatably supported via bearings coaxially with the output shaft 3, and a planetary gear mechanism is used between the transmission shaft 4 and the output shaft 3. A large speed reduction mechanism 12 is provided. The large reduction mechanism 12 is disposed on the base side in the rear axle case 23, and a sun gear 34 is formed on the output shaft 3, and a planetary gear 35
Is fitted to the inner end of the transmission shaft 4.

As shown in FIGS. 1 to 4, 10 and 11, a gear transmission mechanism (final transmission mechanism) 7 is provided between the transmission shaft 4 and a rear wheel shaft 6 on which the rear wheel 5 is mounted. ing. This gear transmission mechanism 7 is a reduction mechanism, and a gear case 11
A first gear 8 rotatably provided integrally with a support shaft 43 rotatably supported about a left-right axis at an upper portion of the inside, and rotating about a left-right axis below the first gear 8; A second gear 9 provided on the rear wheel shaft 6 that is freely supported, and an idler gear shaft 17 that is supported on the front side of the first gear 8 and the second gear 9 so as to be rotatable around a left-right axis. And an idler gear 10 that meshes with the first gear 8 and the second gear 9 simultaneously.

When the tread of the rear wheel 5 is long as shown in FIGS. 1 and 2, the support shaft 43 is interlocked with the transmission shaft 4 via a joint shaft 45 disposed in an extension axle case 42. I have. That is, the joint shaft 45 and the support shaft 43 are interlocked and connected by the coupling 44 spline-fitted to the outer end side of the joint shaft 45 and the inner end side of the support shaft 43, and the inner end side of the joint shaft 45 is The joint shaft 45 and the transmission shaft 4 are interlockingly connected by a coupling 46 spline-fitted to the outer end side of the transmission shaft 4, whereby the support shaft 43 is interlockingly connected to the transmission shaft 4. .

3 and 4, when the tread of the rear wheel 5 is short, the transmission shaft 4 is spline-fitted to the coupling 44, so that the support shaft 43 is interlocked and connected to the transmission shaft 4. ing. The joint shaft 45 is positioned by the coupling 44 abutting on a bearing 47 supporting the support shaft 43 and the coupling 46 abutting on a bearing 48 supporting the transmission shaft 4. In the above configuration, the rotation of the output shaft 3 of the rear wheel differential mechanism 2 is controlled by the large reduction mechanism 1
2, the power is transmitted to the transmission shaft 4 after being greatly reduced, transmitted from the transmission shaft 4 to the rear wheel shaft 6 through the gear transmission mechanism 7 at a slightly reduced speed, and drives the rear wheel 5 in the same direction as the output shaft 3. It is designed to gain forward power.

As described above, since the large reduction mechanism 12 having a larger reduction ratio than the gear transmission mechanism 7 is provided between the output shaft 3 of the rear wheel differential mechanism 2 and the transmission shaft 4, the gear transmission mechanism 7 , The diameter of the second gear 9 can be reduced, and the gear transmission mechanism 7 can be made compact. Also,
In the gear transmission mechanism 7, the idler gear 10 is
The three gears are arranged in front of the gear 8 and the second gear 9, and these three gears are arranged in a triangular arrangement, and are housed in one gear case 11, so that the stress applied to the idler gear 10 during forward movement is reduced. It can withstand large loads.

Further, an output shaft 3 of a rear wheel differential mechanism 2 driven to rotate in the same direction as the rear wheel rotation direction by the power from the bevel pinion 13, and a transmission shaft to which power in the same direction is transmitted from the output shaft 3 4, a large speed reduction mechanism 12 is provided, and a gear transmission mechanism 7 is provided between the transmission shaft 4 and a rear wheel shaft 6 on which the rear wheel 5 is mounted, and the gear transmission mechanism 7 is provided on the transmission shaft 4. A first gear 8, a second gear 9 provided on the rear wheel shaft 6 below the first gear 8, and an idler gear 10 which meshes with the first gear 8 and the second gear 9 at the front side thereof at the same time. This allows the gear transmission mechanism 7 to increase the ground height of the vehicle body, makes the rotation direction of the output shaft 3 and the rear wheel shaft 6 the same, and makes the rear wheel differential mechanism 2 different from the one with a low ground height. Can be configured without causing the idler gear 10 to move forward. Stress reduces, it will be able to withstand the large load.

The ground height (vehicle height) from the ground surface to the bottom surface of the vehicle body 22 can be increased by a length corresponding to the center-to-center distance between the first gear 8 and the second gear 9, and a gear transmission mechanism is provided. 7 is a reduction mechanism having a small reduction ratio, the outer diameter of the second gear 9 is small, and therefore the outer diameter of the lower part of the gear case 11 is also small, and the ground height from the ground surface to the bottom surface of the gear case 11 is high. It has become very convenient for porting work. 10 and 12, when the vehicle body 22 travels forward, the first gear 8 and the first gear 8 rotate counterclockwise as viewed from the left side, and the idler gear 10 rotates clockwise (rotation direction is FIG. 11).

At this time, in the idler gear 10,
It receives a pushing force f1 due to meshing with the first gear 8 and a reaction force f2 in the direction of the center line, and these forces f1, f
2 produces a resultant force FA. In addition, the idler gear 10
It receives a pushing reaction force f3 due to meshing with the second gear 9 and a reaction force f4 in the center line direction, and these forces f3, f4
Produces a resultant force FB. The forces f1, f2, f3, f4
Are indicated by vectors of the same length for convenience, the pushing force f1 is substantially directed to the second gear 9, and the pushing force f3 is substantially directed to the first gear 8.

The composite force FA, FB of the idler gear 10
Are in directions substantially opposite to each other and cancel each other out, so that the combined total force is a force sufficiently smaller than the combined forces FA and FB, and the load applied to the idler gear 10 and the idler gear shaft 17 supporting the idler gear 10 is sufficiently increased. Become smaller. On the other hand, when the vehicle body 22 travels backward as shown in FIG. 13, the first gear 8 and the second gear 9 rotate clockwise as viewed from the left side, and the idler gear 10 rotates counterclockwise. .

At this time, in the idler gear 10,
It receives the pushing force f1 due to meshing with the first gear 8 and the reaction force f2 in the center line direction, and receives the pushing reaction force f3 due to meshing with the second gear 9 and the reaction force f4 in the center line direction. This is the same as in the case of forward movement, but the pushing force f1 acts in a direction away from the second gear 9, and the pushing force f3 acts in a direction away from the first gear 8. Therefore, the resultant force of these forces is the combined force FA by the forces f1 and f2.
And a resultant force FB is generated by the forces f3 and f4, and these resultant forces FA and FB act in a direction away from the first gear 8 and the second gear 9, and the total force obtained by combining the resultant forces FA and FB is a resultant force FA, F
The force is sufficiently larger than B, and the load applied to the idler gear 10 and the idler gear shaft 17 supporting the idler gear 10 is increased.

By the way, in the tractor 21 or the like, most of the forward work performed by attaching a work machine to the rear portion, and the tractor 21 receives a large load such as a towing load during forward movement, and the reverse travel only requires a light load by performing a direction change or the like. . Therefore, in the tractor 21 that performs a large load operation when moving forward, the idler gear 10
Is disposed on the front side of the first gear 8 and the second gear 9, the stress applied to the idler gear 10 can be greatly reduced, and the durability can be improved.

However, in the tractor 21 which frequently performs a large load operation while moving backward, the idler gear 10 is disposed behind the first gear 8 and the second gear 9 to thereby reduce
The stress applied to the idler gear 10 can be greatly reduced. A front axle case (front axle case) 49 is disposed on the lower front side of the tractor 21 in the left-right direction. The front axle case 49 is provided on a front axle bracket whose center in the left-right direction projects forward from the engine. A gear case 50 that accommodates a bevel gear transmission mechanism, a final reduction mechanism, and the like is provided at a laterally outer end side of the front axle case 49 so as to be rotatable around a longitudinal axis.
The front wheel 41 is rotatably supported at zero.

Note that the gear case 50 is a front axle case 4
9 and an outer case rotatably supported around the kingpin axis by the inner case, the front wheel 41 being protruded from the outer case. The disc is attached to the wheel axle and is used as a steering wheel. In the illustrated example, the front wheel 41 is formed to have substantially the same diameter as the rear wheel 5. The gear case 50 is also used as the gear case 11 on the rear wheel 5 side.
Similarly, the extended axle case 5 is detachably mounted and fixed to the left and right outer ends of the front axle case 49 by bolts or the like.
1 is attached and fixed detachably to the left and right outer ends with bolts and the like, and is attached to the left and right outer ends of the front axle case 49 directly and detachably attached and fixed with bolts and the like. The treads of the left and right front wheels 41 can be adjusted to two types of treads corresponding to the tread adjustment of the rear wheels 5.

A gear case 50 is provided on the inner peripheral side of the front wheel 41.
When the front wheel 41 is attached to the gear case 50 so that the front wheel 41 is intruded, the gear case 50 is prevented from interfering with the crop A located inside the front wheel 41 and the tread of the front wheel 41 is lengthened. In addition, since the gear case 50 moves together with the front wheels 41, even when the height of the crop A is high, the gear case 11 is prevented from interfering with the crop A. The power transmission structure when the extension axle case 51 is provided and when it is not provided is substantially the same as the case of the rear wheel 5.

As shown in FIGS. 5 to 7, the left front wheel 41 is provided.
An auxiliary step device 53 is provided between the vehicle and the rear wheel 5. The auxiliary step device 53 includes the tractor 2
1, the vehicle body is provided with an upper auxiliary step 54 and a lower auxiliary step 55 because the vehicle body height is set high. Support 56 supporting upper auxiliary step 54
As shown in FIGS. 14 to 17, a mounting plate 57 is fixed to the side of the vehicle body 22 by bolts or the like, and a bracket 58 fixed to the mounting plate 57 in a laterally outwardly projecting manner by welding or the like. And a reinforcing member 59 for connecting the mounting plate 57 to the middle part of the bracket 58 in the left-right direction, and the upper auxiliary step 54 is fixed to the upper surface of the bracket 58 on the outer end side in the left-right direction by welding or the like. I have.

As shown in FIGS. 14 and 18 to 20, a support body 60 for supporting the lower auxiliary step 55 includes a left-right mounting body 61 mounted and fixed to a bracket 58 of the support body 56. The bracket 62 is fixed to the outer end of the mounting body 61 in the left-right direction in the left-right direction as it moves downward in the left-right direction. It is fixed to the side by welding or the like. The bracket 58 of the support 56 that supports the upper auxiliary step 54 is formed in a downward open U-shape from front and rear walls 58a and 58b and an upper wall 58c that connects upper ends of the front and rear walls 58a and 58b. Three insertion holes 63 are formed in the walls 58a and 58b at intervals in the left-right direction.

The mounting body 61 of the support body 60 for supporting the lower auxiliary step 55 includes front and rear walls 61a and 61b and an upper wall 61c connecting the upper ends of the front and rear walls 61a and 61b.
The bracket 58 is formed in a downward open U-shape, and is fitted between the front and rear walls 58a, 58b of the bracket 58 so as to be movable in the left-right direction. The front and rear walls 61 of the mounting body 61
Two insertion holes 64 are formed in a and 61b at the same interval as the interval between the insertion holes 63 formed in the bracket 58. Then, as shown in FIG. 21, the insertion holes 63, 64 formed in the bracket 58 and the mounting body 61 are aligned, a bolt 65 is inserted into the insertion holes 63, 64, and a nut 66 is inserted into the bolt 65. The attachment body 61 is configured to be detachably fixed to the bracket 58 by being screwed together.
The position can be freely changed to two positions in the left-right direction corresponding to the treads 1 and 5, and the lower auxiliary step 55 is considered so as not to interfere with the crop A.

As shown in FIG. 14 and FIGS.
A handrail 67 is provided on the front side of the auxiliary step device 53. The handrail 67 is provided with connecting portions 70 connecting the upper and lower struts 68 and 69 in the left-right direction, a connecting portion 70 connecting the upper ends of the inner and outer props 68 and 69, and a connecting portion connecting the middle portions of the inner and outer supporting portions 68 and 69 in the vertical direction. 73 and a main configuration,
A mounting plate 71 fixed to a side portion of the vehicle body 22 with bolts or the like is fixed to a lower end portion of the inner support portion 68, and an upper auxiliary step 54 of the auxiliary step device 53 is fixed to a lower end portion of the outer support portion 69. A mounting plate 72 fixed by bolts or the like is fixed to the front side of the device.

The strength of the handrail 67 is increased by a connecting portion 73, and the strength of the auxiliary step device 53 is increased by connecting the vehicle body 22 and the auxiliary step device 53 (upper auxiliary step 54). Thus, resonance from vibration from the engine is prevented. The gear transmission mechanism 7 is decelerated at a small ratio, but can be set to a constant speed or a speed increase.
In addition, the distance from the center line connecting the first gear 8 and the second gear 9 to the idler gear 10 can be set variously, and even if the first gear 8 and the idler gear 10 are formed to have the minimum diameter that can be cut. A sufficient distance between the first gear 8 and the second gear 9 can be provided.

[0034]

According to the present invention described in detail above, the wheels are attached to the gear case so that the gear case enters the inner peripheral side of the wheels, so that the gear case can be prevented from contacting the crop. The extended axle case is interposed between the axle case and the gear case by being detachably attachable to the axle case so that the extended axle case can be interposed between the axle case and the gear case. Thus, the tread adjustment can be performed while maintaining the state where the gear case enters the inner peripheral side of the wheel.

A gear transmission mechanism housed in a gear case is provided between a transmission shaft to which power is transmitted from an output shaft of a rear wheel differential mechanism and a rear wheel shaft on which the rear wheel is mounted. A first gear operatively connected to the transmission shaft;
A second gear provided on the rear wheel shaft below the first gear, and an idler gear meshing with the first gear and the second gear at the same time, the idler gear being at the front or rear of the first gear and the second gear. By disposing it on the side, the gear transmission mechanism can raise the ground height of the vehicle body, and the output shaft and the rear wheel shaft rotate in the same direction, and if the rear wheel differential mechanism is different from the one with a low ground height, It is possible to configure without making it.

Further, since the idler gear is arranged in front of the first gear and the second gear and the three gears are arranged in a triangular shape and housed in the gear case, the stress applied to the idler gear during forward movement is reduced, so that a large load is applied. Be able to endure. In addition, the transmission shaft and the support shaft supporting the first gear can be interlockedly connected via a coupling,
The tread is extended in the extended axle case simply by adding a joint shaft interlockingly connected to the support shaft supporting the first gear via the coupling and a coupling interlockingly connecting the joint shaft and the transmission shaft. In this case, power can be transmitted from the transmission shaft to the first gear.

Further, the auxiliary steps provided between the front wheel and the rear wheel can be adjusted to the left and right positions in accordance with the tread adjustment of the wheels, so that the auxiliary steps arranged at a lower position contact the crop. Can be prevented. Also, by connecting the vehicle body and the auxiliary step by handrail,
The resonance of the auxiliary step against the vibration from the engine can be prevented.

[Brief description of the drawings]

FIG. 1 is a rear sectional view of a main part.

FIG. 2 is a rear sectional view of a main part.

FIG. 3 is a rear sectional view of a main part.

FIG. 4 is a rear sectional view of a main part.

FIG. 5 is a side view of the tractor.

FIG. 6 is a plan view of the tractor.

FIG. 7 is a front view of the tractor.

FIG. 8 is a rear view of the tractor.

FIG. 9 is a front view of the tractor.

FIG. 10 is a side view of the gear transmission mechanism.

FIG. 11 is a configuration diagram of a rear wheel power transmission system.

FIG. 12 is an explanatory diagram of stress applied to the idler gear during forward movement.

FIG. 13 is an explanatory diagram of a stress applied to the idler gear during reverse movement.

FIG. 14 is a front view of a handrail and an auxiliary step device.

FIG. 15 is a front view of the upper auxiliary step and the support.

FIG. 16 is a plan view of the upper auxiliary step and the support.

FIG. 17 is a side view of the upper auxiliary step and the support.

FIG. 18 is a front view of a lower auxiliary step and a support.

FIG. 19 is a plan view of a lower auxiliary step and a support.

FIG. 20 is a side view of the lower auxiliary step and the support.

21 is a sectional view taken along the line BB of FIG.

FIG. 22 is a front view of a handrail.

FIG. 23 is a side view of the handrail.

FIG. 24 is a plan view of a handrail.

[Explanation of symbols]

 Reference Signs List 2 rear wheel differential mechanism 3 output shaft 4 transmission shaft 5 rear wheel 6 rear wheel shaft 7 gear transmission mechanism 8 first gear 9 second gear 10 idler gear 11 gear case 13 bevel pinion 22 vehicle body 23 rear axle case 41 front wheel 42 extension case 44 coupling 49 Front axle case 51 Extension case 55 Lower auxiliary step 67 Handrail

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Koji Sonoi 64 Ishizukita-cho, Sakai City, Osaka Inside Kubota Sakai Works (72) Inventor Noriaki Takewa 64 Ishizukita-cho, Sakai City, Osaka Kubota Corporation Sakai Works

Claims (6)

[Claims] A gear case is provided on an outer end in the left-right direction of an axle case provided in a laterally outwardly projecting shape, and a wheel is mounted on the gear case so that the gear case enters an inner peripheral side of the wheel. A tractor characterized in that a gear case is detachably attachable to an axle case so that an extension axle case can be interposed between the axle case and the gear case. 2. A gear transmission mechanism housed in a gear case is provided between a transmission shaft to which power is transmitted from an output shaft of a rear wheel differential mechanism and a rear wheel shaft on which a rear wheel is mounted. A first gear interlockingly connected to the transmission shaft, a second gear provided on the rear wheel shaft below the first gear,
The tractor according to claim 1, wherein the tractor is formed by a gear and an idler gear that meshes with the second gear at the same time, and the idler gear is disposed on the front side or the rear side of the first gear and the second gear. 3. The tractor according to claim 2, wherein the idler gear is arranged in front of the first gear and the second gear, and the three gears are arranged in a triangular arrangement in a gear case. 4. The tractor according to claim 2, wherein the transmission shaft and a support shaft supporting the first gear can be interlocked and connected via a coupling. 5. The tractor according to claim 1, wherein an auxiliary step provided between the front wheel and the rear wheel is capable of adjusting a right and left position corresponding to a tread adjustment of the wheel. . 6. The tractor according to claim 1, wherein the vehicle body and the auxiliary step are connected by a handrail.