JPH10295134A - Working vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a working vehicle capable of facilitating turning operation at a slope, also automatically preventing a vehicle body from going downward at the time of working while traveling on a contour line at the slope, hardly being tilted or fallen down at the time of parking and capable of facilitating turning operation at a level land. SOLUTION: A right/left pair of front wheels 10 is integrally arranged with a main frame 2 arranging a rear wheel in the state of being freely rockable up and down, the forward/backward direction of the rotating axis O of the front wheels 10 varies corresponding to the vertical rocking angle of a pair of front wheels 10 with respect to the frame 2 and in order to suppress the variation of the vertical rocking of the wheels and the forward/backward direction of the rotating axis, coil springs 71 and 72 as elastic energizing means are arranged between the frame 2 and the front wheels 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a work vehicle for performing mowing and spraying work while traveling, and more particularly to a work vehicle for a slope land suitable for performing work while traveling on a contour line on a slope.

[0002]

2. Description of the Related Art A working vehicle that performs mowing or spraying work while traveling is usually designed to be suitable for work on a flat surface that is not inclined, and therefore works while traveling on a contour line on an inclined surface. Is performed, the work is performed in a state in which the entire vehicle such as the main body frame and the front wheels, rear wheels, prime mover, and working unit disposed on the main body frame are inclined along a slope.

However, when the entire vehicle is tilted along the slope as described above, there is a dislike for the work vehicle to fall in the downward direction of the slope due to the own weight of the work vehicle and work resistance (such as mowing resistance) in mowing work. . Therefore, in order for the work vehicle to travel on the contour line, the operator must always perform the work by operating the work vehicle so that the work vehicle does not face downward. There was also the problem of being bad and the danger of falling.

Therefore, the applicant of the present invention has previously proposed a new work vehicle capable of solving the above-mentioned problem, as described in Japanese Patent Application No. 8-216604. Basically, this work vehicle has a pair of left and right front wheels integrally disposed so as to be able to swing up and down integrally with a main body frame on which rear wheels are disposed, and the upper and lower sides of the pair of front wheels with respect to the main body frame. The direction in the front-rear direction of the rotation axis of the front wheel is automatically changed according to the swing angle.

More specifically, the front wheel is attached to a working portion such as a mowing blade, a cover, and the like, and a front-rear axis extending in the front-rear direction is provided on the main body frame, and the working portion and the front wheel are connected to each other. It is arranged so that it can swing up and down with the longitudinal axis as the swing center axis.

In such a work vehicle, for example, when performing a work (eg, mowing work) while traveling on a contour line on a slope, the rear wheel disposed at the rear center of the main body frame is arranged so as to follow a vertical line. The left and right front wheels, which are arranged to be swingable with respect to the main body frame, are in a posture substantially perpendicular to an inclined surface (a mowing work surface), and thus inclined with respect to a vertical line. The working part provided with the front wheels is disposed substantially parallel to the inclined surface.

In this case, depending on the vertical swing angle of the pair of front wheels with respect to the main body frame, in other words, according to the inclination angle of the sloping ground, for example, with respect to the swash plate portion provided on the front wheel or the working portion side. The contact position of a pressing member such as a roller attached to the main body frame is changed, the rotation axis of the pair of front wheels is changed in the front-rear direction, and the resistance that the front wheels receive during forward movement is changed.
The direction of travel of the front wheels can be automatically changed in the direction of climbing the slope without any switching operation.

In this way, when the work is performed while traveling on a contour line on an inclined ground, the direction of the rotation axis of the front wheel is automatically changed, so that the traveling direction of the front wheel changes in the direction of climbing the inclined ground. The vehicle body is automatically prevented from going downward. This provides an advantage that the operation can be performed efficiently, easily, and safely.

[0009]

However, as a result of further studies by the present inventors on the work vehicle as described above, in the work vehicle, a pair of left and right front wheels and a work portion are vertically swung. In addition to being made freely, the front wheel is configured such that the direction of the axis of rotation of the front wheel in the front-rear direction is changed.

That is, when turning on a slope, the front wheel and the working part are usually lifted with the rear wheel as a fulcrum. At this time, if the front wheel and the working part can freely swing up and down, they are planted. It is easy to wobble, it is difficult to turn, it is easy to fall or fall, and it is difficult to hold the posture when parking etc. (when a person is away) When turning on a flat ground, the front wheel and the working unit can swing freely when turning on flat terrain.

The present invention has been made in view of such a problem, and an object of the present invention is to automatically determine that a vehicle body is directed downward when working on a slope while traveling on a contour line. It is possible to perform work efficiently and easily and safely.Moreover, it is possible to easily perform turning operations on slopes, and it is difficult to lean or fall when parking etc. An object of the present invention is to provide a work vehicle that can easily perform a turning operation of a vehicle.

[0012]

In order to achieve the above object, a work vehicle according to the present invention basically comprises a pair of left and right front wheels integrally formed with a main body frame provided with rear wheels. The front wheel is arranged so as to be vertically swingable, and the direction of the rotation axis of the front wheel in the front-rear direction changes according to the vertical swing angle of the pair of front wheels with respect to the main body frame.

An elastic biasing means is provided between the main body frame and the front wheel so as to suppress the vertical swing of the front wheel and a change in the direction of the rotation axis in the front-rear direction. I have.

In a more preferred specific embodiment, the front wheel is attached to a working portion, and the main body frame is provided with a front-rear shaft extending in the front-rear direction.
The working portion and the front wheel are vertically swingably disposed about the longitudinal axis as the pivot axis, and a pair of the elastic urging means is provided on the left and right of a central axis of the longitudinal axis in plan view. Is mounted.

In a further preferred specific embodiment, the front wheel is rotatably supported by the working portion in a plane parallel to a rotation axis thereof, and one of the pair of front wheels or the main body frame is provided with the center axis. A swash plate unit having a swash plate portion that is inclined with respect to the swash plate portion, and a pressing member that is slidably or rollably abutted on the swash plate portion is attached to the other, and the front wheel is vertically moved with respect to the body frame. The contact position of the pressing member against the swash plate portion is changed according to the swing angle, whereby the front-rear direction of the rotation axis of the front wheel is changed, and Are arranged in parallel between the main body frame and the swash plate unit in parallel with the central axis.

In another preferred embodiment, a lock mechanism is provided which can prevent vertical swing of the front wheel and a change in the direction of the axis of rotation of the front wheel in the front-rear direction as required. In this case, in a more preferable specific mode, the lock mechanism includes a lock pin that is inserted into and removed from a locking hole formed in the swash plate portion.

Although the working vehicle of the present invention is not limited in its use, the working unit is a mowing work unit, that is, used as a forestry and forestry machine for performing mowing work on a slope such as a mountain. It is suitable for.

In a preferred embodiment of the work vehicle according to the present invention having such a configuration, when performing work (eg, mowing work) while traveling on a contour line on a slope, the work vehicle is disposed at the rear center of the main body frame. The rear wheel is set up along the vertical line, but the pair of left and right front wheels that are swingably disposed with respect to the main body frame are substantially perpendicular to the inclined surface (the mowing work surface). The working part (mowing blade, cover, etc.) on which the front wheel is disposed is arranged substantially parallel to the inclined surface with respect to the vertical line.

In this case, according to the vertical swing angle of the pair of front wheels with respect to the main body frame, in other words, according to the inclination angle of the sloping ground, for example, the swash plate portion provided on the front wheel or the working portion side is provided. The contact position of the pressing member attached to the main body frame is changed, the front-rear direction of the rotation axes of the pair of front wheels changes, and the resistance of the front wheels at the time of forward movement causes the front wheels to move in an inclined direction. It can be automatically changed in the direction of climbing without requiring a switching operation.

As described above, when performing work while traveling on a contour line on an inclined ground, the direction of the rotation axis of the front wheel is automatically changed, so that the traveling direction of the front wheel can be changed in the direction of climbing the inclined ground. Therefore, the vehicle body can be automatically prevented from going downward, so that the work can be performed efficiently, easily, and safely.

In addition to the above, in the working machine of the present invention,
Between the main body frame and the front wheel, for example, a pair of coil springs are respectively provided as elastic biasing means in parallel with the left and right sides of the center axis of the front-rear direction axis in a plan view, and the biasing force causes Since the vertical swing of the front wheel and the working unit and the change in the front-rear direction of the rotation axis of the front wheel are appropriately suppressed, for example, when turning on a slope,
Even if the front wheel and the working part are lifted with the rear wheel as a fulcrum, they are urged to always return to horizontal by the urging force of the elastic urging means. For this reason, the front wheels and the working unit are less likely to wobble, the turning operation is easier, and the front wheels and the working unit are less likely to tilt or fall.

Further, a lock mechanism that can prevent the front wheel from swinging up and down and changing the direction of the axis of rotation of the front wheel in the front-rear direction as required is provided, for example, when parking (when a person is away). ) And when turning on flat ground, if the lock pin provided in the lock mechanism is inserted into the lock hole of the swash plate and locked in a locked state, it becomes difficult to tilt or fall over, The turning operation becomes easy.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. 1, 2, and 3 are a left side view, a plan view, and a front view showing an embodiment of a work vehicle according to the present invention.

The illustrated work vehicle 1 is used for mowing work. A power plant 3 comprising a four-stroke internal combustion engine as a prime mover is mounted substantially at the center of a main body frame 2, and a power plant 3 which is described below is disposed below the center of the rear part. A single driving rear wheel 20 is provided. Left and right handles 7, 8 are attached to the rear upper side of the main body frame 2 obliquely rearward, and grips 7a, 8a of the handles 7, 8 are provided.
In the vicinity, a throttle operation lever 11, a clutch operation lever 12, and the like for controlling the power plant 3 are provided.

The power plant 3 is provided with a working power take-out shaft 5 (see FIGS. 2 and 4) and a traveling power take-out shaft 6 (see FIGS. 1 and 2). The power is supplied from the working power take-out shaft 5 via a belt-pulley type wrapping transmission mechanism 22 and a power transmission direction changing mechanism 24 to a mowing blade (rotary hammer knife).
And transmitted to the rear wheel 20 via the telescopic universal drive shaft 13, the two-stage transmission 14, and the chain-type wrapping transmission mechanism 16. It is transmitted as a driving force. A slider cup 51 is mounted below the mowing blade 50 so as to rotate integrally therewith.

The power transmission direction changing mechanism 24 interposed between the working power take-out shaft 5 and the mowing blade 50 is, as can be clearly understood from FIGS. 4 and 5, the main body frame. 2, a front-rear power transmission shaft 30 (the center axis is C) arranged along the front-rear direction;
And a longitudinal power transmission shaft 40 disposed orthogonally to the longitudinal power transmission shaft 40. The front-rear direction power transmission shaft 30 has a rear end portion fixed via a ball bearing 31 in a fixed case 25 fixed to the main body frame 2. The front end of the fixed case 25 is rotatably supported by a rotating case 26 via a ball bearing 34. The front end of the fixed case 25 and the rear end of the rotating case 26 Between them, ball bearings 32 and 33 are interposed, respectively.

The vertical power transmission shaft 40 is rotatably supported via ball bearings 41 and 42 in a vertical case 27 fixed to a lower portion of the rotary case 26. The output shaft 2 of the belt-pulley winding transmission mechanism 22 is provided at the rear side of the front-rear power transmission shaft 30.
A first input bevel gear 29 meshing with a first output bevel gear 27 provided on 2a is provided, and a second input bevel gear provided on an upper end portion of the vertical power transmission shaft 40 is provided on a front side thereof. 3
9 is provided, and the mowing blade 50 provided at the lower end of the vertical power transmission shaft 40 rotates in a plane parallel to the front-rear power transmission shaft 30. It is supposed to.

The turning case 26 in which the front half of the front-rear direction power transmission shaft 30 is housed has a front end,
It is rotatably supported via a bearing 47 on a support shaft 46 fixed coaxially with the front-rear direction power transmission shaft 30 on a support plate 44 hanging down and fixed to the main body frame 2 with bolts 45. A substantially cylindrical mowing cover 36 that covers the mowing blade 50 is also fixed to the rotating case 26 in addition to the vertical case 27. At the front of the mowing cover 36, a U-shaped grass collecting pipe frame 19 is disposed so as to project diagonally forward and upward.

Accordingly, the working portion 35 including the rotating case 26, the vertical case 27, the mowing blade 50, and the like, swings up and down with respect to the body frame 2 with the longitudinal power transmission shaft 30 as the swing center axis. It is arranged freely.

The center line of the working section 35 on the front side of the mowing cover 36 (which overlaps with the center axis C of the front-rear direction power transmission shaft 30 in plan view) is shown in FIGS.
, The pivot 55 protrudes vertically upward. The pivot 55 is rotatably inserted into a cylindrical portion 52B provided on a double-walled base portion 52A of a swash plate unit 52 having a substantially "L" shaped cross section in a side view. A bolt 59 as a vertical direction regulating member is screwed through a slide washer 58, and the swash plate unit 52 is
Therefore, the power transmission shaft 30 is rotatably supported in a plane parallel to the mowing cover 36, in other words, in a plane parallel to the front-rear power transmission shaft 30.

At the front of the swash plate unit 52, FIG.
As can be understood by referring to FIG.
A front-wheel supporting U-shaped frame 56 projecting forward from the front end of the front wheel 10 is fixedly mounted by mounting brackets 53, 53, and a pair of left and right front wheels 10 are attached to support shafts 57, 57 provided on the U-shaped frame 56. , 10 are freely rotatably supported.
In other words, the front wheels 10, 10
Are supported through the swash plate unit 52,
7 (rotation axis O) so as to be rotatable in the front-rear direction in a plane parallel to the rotation axis O.

A swash plate portion 52a, which is a vertical surface on the rear side of the swash plate unit 52, is slightly inclined rearward with respect to the center axis C of the mowing cover 36 and the longitudinal power transmission shaft 30. The swash plate portion 52a is held and fixed to the left and right end portions on the rear surface side of the swash plate portion 52a at positions parallel to the main body frame 2 in the front-rear direction and symmetrical with respect to the center axis C. Two support rods 61,
Barrel-shaped rollers 63 and 64, which are pressed members that protrude left and right from the distal end of the shaft 62 and are supported, are brought into contact with each other.

In addition to the above, in the present embodiment, the swash plate unit 52 is provided in order to suppress the vertical swing of the front wheels 10, 10 and the working portion 35 and the change in the front-rear direction of the rotation axis O of the front wheels. Between the body frame 2
A pair of coil springs 71 and 72 having the same tensile force as the elastic urging means are parallel to a position symmetrical left and right with respect to the center axis C of the longitudinal power transmission shaft 30 in plan view. Are installed side by side.

More specifically, near the left and right ends of the double-walled base portion 52A of the swash plate unit 52, a front gate-shaped support member 73 which is symmetrical with respect to the center axis C is provided. Are vertically fixed to the mounting brackets 53, 53, and the pair of support rods 61,
On both sides of the front gate-shaped support member 73, the rear gate-shaped support member 73 and the rear gate-shaped support member 73 are fixed on the rear side. The coil spring 7 is connected so as to bridge the support member 74.
1,72 are installed.

In addition to the above, in the present embodiment, the vertical swing of the front wheels 10, 10 and the working portion 35 and the change in the front-rear direction of the rotation axis O of the front wheels 10, 10 are prevented as necessary. To this end, a lock mechanism 75 is provided on a support plate 66 provided between the support rods 61 and 62.

The lock mechanism 75 can be easily understood by referring to FIG. 8 in addition to FIGS.
Insertion / extraction portion 76a having a tip portion 76c tapered, which is inserted / removed into / from a locking hole 52c formed at the center in the left-right direction of FIG.
A lock pin 76 having a base, a cylindrical storage tube portion 75A with a pedestal 75C for supporting and guiding the lock pin 76,
A lid-like spring receiving member 75B attached to the rear end of the storage cylinder portion 75A and a small-diameter portion 76b on the rear end side of the lock pin 76 are slidably disposed in the storage cylinder portion 75A. And a coil spring 78 contracted between the slider 76A and the spring receiving member 75B to constantly urge the lock pin 76 forward.
The pedestal 75C is fixed to the support plate 66 with bolts 67,67.

The front end of the inner cable 77a of the Bowden cable 77 routed in the front-rear direction of the body frame 2 is connected to the rear end of the lock pin 76, and the rear end of the inner cable 77a Is connected to an operation lever 79 disposed near the left end of the horizontal member 9 disposed between the left and right handles 7, 8, as can be clearly understood from FIGS.

Therefore, when the operation lever 79 is tilted to the release position on the rear side and locked, for example, the lock pin 7 is released.
As shown by the phantom line in FIG. 8, 6 is pulled rearward through the Bowden cable 77 against the urging force of the coil spring 78 and pulled out from the locking hole 52c of the swash plate portion 52a. Lock release holding state,
Conversely, when the operation lever 79 is released from the release position, the lock pin 76 is caused to protrude forward by the urging force of the coil spring 78 as shown by a solid line in FIG. By operating the handles 7 and 8 to align the position of the lock pin 76 with the lock hole 52c of the swash plate portion 52a, the tip end portion 76C of the lock pin 76 is inserted into the lock hole 52c. Become.

The front wheels 10, 10 have a saw-toothed or star-shaped outer peripheral shape in which a predetermined number (here, 18) of mountain-like portions 10c, 10c,... Are formed at a predetermined angle α (20 degrees) interval. Left and right pair of steel plates 10a, 1
0a and a perforated plate material such as a band-shaped expanded metal obtained by forming a notch on a steel plate and performing tensile expansion processing, by using the vehicle plate 10a,
And an inner cylinder wheel 10b formed by rolling into a cylindrical shape having an outer radius Rb smaller than the outer radius Ra of 10a.

The pair of left and right vehicle plates 10a, 10
a, the inner cylinder wheel 10b is arranged so as to have a common rotation axis O with the vehicle plates 10a, 10a, and is integrally connected to each other.

The rear wheels 20, 20 have a sawtooth-shaped or star-shaped outer peripheral shape in which a large number (here, 24) of mountain-shaped portions 20c, 20c,... Are formed at predetermined angular intervals (15 degrees). A pair of left and right vehicle boards 20a, 20a, and a predetermined number (here, 24 pieces of the same number of the mountain-shaped portions 20c) of angled steel angle members 20b, 20b,.

The pair of left and right vehicle plates 20a, 20
between a, the angle member 20b, 20b, ... with a predetermined angle (15 degrees) intervals, one end portion 20b ₁ is the wheel plate 10a, on concentric circles of the outer radius becomes smaller than the outer peripheral radius of 10a (center) They are arranged to be located and connected to them.

In the working vehicle 1 of this embodiment having such a configuration, as can be clearly understood from FIG. 3, the mowing work is performed while traveling on a contour line on a slope P inclined with respect to a flat ground E. When performing the operation, the operation lever 7
9, the lock pin 76 is pulled out of the locking hole 52 of the swash plate portion 52a.
The rear wheel 20 is set up along the vertical line G by operating the handles 7, 8. A pair of front wheels 1 which are vertically swingable as C
0, 10 are substantially perpendicular to the inclined plane P, and therefore inclined with respect to the vertical line G,
The working unit 35 on which the 10 is disposed is arranged substantially parallel to the inclined surface P.

In this case, according to the vertical swing angle of the front wheels 10, 10 with respect to the main body frame 2, in other words, according to the inclination angle of the sloping ground, as can be understood from FIG. , 10 and the working unit 35
The contact position of the barrel-shaped rollers 63 and 64 attached to the main body frame 2 side with respect to the swash plate portion 52a of the swash plate unit 52 attached to the side is changed, and the rotation axis O of the front wheel 10 is changed. As indicated by the imaginary line O ', the front wheels 10, 10 are automatically changed in the direction of climbing the sloping ground without any operation due to the resistance of the front wheels 10, 10 when moving forward.

As described above, when performing work while traveling on a contour line on a slope, the direction of the rotation axis O of the front wheels 10, 10 is automatically changed to the direction of climbing the slope, so that the vehicle body moves downward. Heading can be automatically prevented, so that work can be performed efficiently, easily and safely.

In addition to the above, a pair of coil springs 7 are provided between the main body frame 2 and the swash plate unit 52.
The front and rear power transmission shafts 3 are respectively shown in plan view.
0 and parallel to the center axis C of the front wheel 10, and the urging force causes the front wheels 10, 10 and the working unit 35 to swing up and down and change the direction of the rotation axis O of the front wheels 10, 10 in the front-rear direction. For example, when turning on a slope, the front wheel 10,
Even when the work unit 10 and the working unit 35 are lifted, they are urged by the urging forces of the coil springs 71 and 72 so as to always return to a horizontal position. Therefore, the front wheels 10, 1
0 and the working unit 35 are less likely to wobble, the turning operation is easier, and the working unit 35 is less likely to tilt or fall.

Further, a lock mechanism 75 capable of preventing the vertical swing of the front wheels 10, 10 and the change of the direction of the rotation axis O in the front-rear direction as necessary is provided, so that, for example, when the vehicle is parked (person The operating lever 79 is released from the release position, and the lock pin 76 provided in the lock mechanism 75 is engaged with the locking hole of the swash plate portion 52a. If it is inserted into 52c and locked, it becomes difficult to tilt or tip over, and the turning operation becomes easy.

As described above, one embodiment of the present invention has been described in detail. However, the present invention is not limited to the above-described embodiment, and a design may be made without departing from the spirit of the invention described in the appended claims. , Various changes can be made.

For example, in the above-described embodiment, the front-rear direction power transmission shaft 30 is used as the swing center axis C of the working unit 35 and the front wheels 10, 10, but this is not necessarily required. Needless to say, a shaft may be separately provided.

Although the front wheel swings integrally with the working unit, the front wheel alone may swing alone.

Further, in the above embodiment, the working machine has been described as a mowing machine, but the working machine is not limited to the mowing machine, but can be applied to other working machines such as a spraying working machine.

[0052]

As will be understood from the above description, according to the working vehicle of the present invention, the front wheels are adjusted according to the vertical swing angle of the front wheels with respect to the main body frame, in other words, according to the inclination angle of the sloped ground. The direction of the axis of rotation can be automatically changed in the direction of climbing the sloping land without the need for switching operation, so that the body can be automatically prevented from going down, so work can be done efficiently, easily and safely In addition to being able to do it, it is possible to easily perform turning operations on sloping ground, and it is difficult to tilt or fall when parking etc.
In addition, there is an excellent effect that the turning operation on flat ground can be easily performed.

[Brief description of the drawings]

FIG. 1 is a schematic left side view showing an embodiment of a work vehicle according to the present invention.

FIG. 2 is a schematic plan view of the work vehicle shown in FIG.

FIG. 3 is a schematic front view of the work vehicle shown in FIG.

FIG. 4 is an enlarged view of a front half of the work vehicle shown in FIG. 1;

5 is a partially cutaway enlarged view showing a main part of the work vehicle shown in FIG. 4 in an enlarged manner.

FIG. 6 is an enlarged plan view showing a front portion of the work vehicle shown in FIG.

FIG. 7 is an exploded perspective view for explaining a manner of mounting the front wheels of the work vehicle shown in FIG. 1;

FIG. 8 is a partially cut-away enlarged side view showing details of a lock mechanism attached to the work vehicle shown in FIG. 1;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 mowing work vehicle 2 main body frame 10 front wheel 20 rear wheel 30 front and rear power transmission shaft (front and rear shaft) 35 working unit (mowing working unit) 52 swash plate unit 52a swash plate unit 52c locking holes 63, 64 barrel roller ( Pressing member) 71, 72 Coil spring (elastic urging means) 75 Lock mechanism 76 Lock pin O Rotation axis of front wheel C Center axis of front-rear direction power transmission shaft

Claims (6)

[Claims] 1. A pair of left and right front wheels (10, 10) are integrally disposed on a main body frame (2) on which a rear wheel (20) is disposed so as to be swingable up and down. A work vehicle (1) in which the front-rear direction of the rotation axis (O) of the front wheels (10, 10) changes according to the vertical swing angle of the pair of front wheels (10, 10) with respect to (2). In 1), between the body frame (2) and the front wheels (10, 10), in order to suppress the vertical swing of the front wheels (10, 10) and the change in the direction of the rotation axis (O) in the front-rear direction. A work vehicle characterized in that elastic biasing means (71, 72) are disposed on the vehicle. 2. The front wheel (10, 1) is attached to a working section (35).
0) is attached and a longitudinal axis (3) extending along the longitudinal direction of the main body frame (2).
0) is provided, and the working unit (35) and the front wheel (1) are provided.
0, 10) are vertically swingable about the longitudinal axis (30) as the swing center axis, and are disposed on the left and right of the central axis (C) of the longitudinal axis (30) in plan view. A pair of coil springs (71, 7) as elastic biasing means
The work vehicle according to claim 1, wherein 2) is installed. 3. The working part (35) is provided with the front wheels (10, 10).
10) is rotatably supported in a plane parallel to the rotation axis (O), and one of the pair of front wheels (10, 10) or the main body frame (2) is connected to the center axis (C). A swash plate unit (52) having a swash plate portion (52a) inclined with respect to the swash plate portion (52a) is provided, and a pressing member (63, 64) slidably or rollably abutting the swash plate portion (52a). ) Is attached, and the contact position of the pressing members (63, 64) against the swash plate portion (52a) changes according to the vertical swing angle of the front wheels (10, 10) with respect to the main body frame (2). The direction of the rotation axis (O) of the front wheels (10, 10) in the front-rear direction is thereby changed, and the pair of coil springs (71, 72) are respectively connected to the main body. Frame 2 and Working vehicle according to claim 2, characterized in that it is parallel to parallel the center axis (C) and between the Kihasuban unit (52). 4. A lock mechanism (75) capable of preventing vertical swing of the front wheels (10, 10) and a change in the direction of the rotation axis (O) in the front-rear direction as required. The work vehicle according to any one of claims 1 to 3, wherein the work vehicle is a vehicle. 5. The lock mechanism according to claim 4, wherein the lock mechanism includes a lock pin that is inserted into and removed from a lock hole formed in the swash plate portion. The working vehicle described. 6. The work vehicle according to claim 1, wherein the work unit is a mowing work unit (35).