JP2002046670A - Six-wheel work vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To minimize a side slip and ridging (mud pushing) of paddy field by first and third wheels for preventing the paddy field from lying waste and for improving turning ability. SOLUTION: Each running part arranges first, second and third wheels in front, middle and rear pars respectively with intervals in a longitudinal direction. A ground clearance can be adjusted in position for the second wheel in the middle part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a six-wheeled working vehicle.

[0002]

2. Description of the Related Art Conventionally, as one form of a six-wheeled working vehicle, a pair of right and left traveling units are connected to a prime mover unit via a transmission unit, and each transmission unit is individually driven by the transmission unit. There is.

[0003] In such a six-wheel working vehicle, the vehicle body is capable of turning by providing a speed difference between the left and right running parts, and by turning each running part in opposite directions, a sharp turn is made. (So-called spin turn)
Can be done.

[0004]

However, in the six-wheeled working vehicle described above, since the contact pressure of each wheel is large, the turning-side wheel slips during turning, especially during a sharp turn, and soil on the field is removed. There is a problem that it rushes to the side and crushes the field.

[0005] In addition, in the crawler type traveling section, although the contact pressure is small, since the center of gravity moves suddenly when crossing a ridge or the like, there is a problem in that the driver gives a sense of fear.

[0006]

Therefore, according to the present invention, a six-wheeled vehicle is structured such that a pair of left and right traveling parts are interlockedly connected to a motor unit via a transmission part, and each transmission part is individually driven by the transmission part. In the working vehicle, each traveling unit arranges first, second, and third wheels at front, center, and rear portions with an interval in the front-rear direction, and the second wheel at the center is positioned at the ground clearance. An object of the present invention is to provide a six-wheel working vehicle characterized by being adjustable.

The present invention also has the following configuration.

[0008] A pair of left and right running parts are provided at a front part, a center part, and a rear part of the vehicle body frame, and extend in the left-right direction.
The second and third wheel axles are mounted horizontally, and the first, second and third wheels are attached to the left and right ends of the respective wheel axles via the first, second and third cylindrical axles, respectively. Each cylindrical axle is interlocked with the mission section to enable the left and right traveling sections to be individually driven, and a second wheel spindle supporting a pair of left and right second wheels is connected to the body frame via a ground height position adjuster. To be adjustable so that the height above the ground can be adjusted.

In a six-wheeled working vehicle, a pair of right and left traveling parts are operatively connected to a prime mover part via a transmission part, and each transmission part is individually driven by the transmission part.
The pair of left and right traveling parts are arranged with first, second, and third wheels spaced apart in the front-rear direction at a front part, a center part, and a rear part of the left and right sides of the body frame. The wheel can be moved up and down by a wheel elevating mechanism.
The wheel lowering operation is linked to the steering wheel turning operation.

[0010] The width of the lowering operation of the second wheel by the wheel lifting mechanism is proportional to the magnitude of the turning steering angle of the steering wheel.

[0011]

Embodiments of the present invention will be described below.

That is, the six-wheeled working vehicle according to the present invention is configured such that a pair of left and right traveling units are interlockedly connected to the prime mover unit via the transmission unit, and each transmission unit is individually driven by the transmission unit. In each of the running sections, the first, second, and third wheels are arranged at front, center, and rear portions with an interval in the front-rear direction, and the second wheel at the center is capable of adjusting the height of the ground. I have.

That is, the pair of left and right traveling parts respectively cross first, second, and third wheel spindles extending in the left-right direction at the front part, the center part, and the rear part of the body frame. The first, second, and third wheels are attached to the first and second
A second wheel support shaft that is mounted via a third cylindrical axle, and that links the respective cylindrical axles with the transmission section so that the left and right running sections can be driven individually and supports a pair of left and right second wheels; Is mounted on the vehicle body frame via a ground height position adjuster so that the ground height position can be adjusted.

The pair of right and left running parts are provided with first, second, and third wheels at front, center, and rear portions on the left and right sides of the vehicle body frame at an interval in the front-rear direction. The second wheel can be raised and lowered by a wheel lifting mechanism, and the lowering operation of the second wheel by the wheel lifting mechanism can be linked to the turning operation of the steering wheel.

In addition, the width of the lowering operation of the second wheel by the wheel elevating mechanism is made to be proportional to the magnitude of the turning steering angle of the steering wheel.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

A shown in FIG. 1 is a work vehicle according to the present invention. The work vehicle A is provided with running parts 2, 2 on the left and right sides of a body frame 1, respectively. The driving unit 3 is disposed at the front, the prime mover unit 4 and the transmission unit 5 are disposed on top of each other at the rear, and the traveling units 2 are linked to the prime mover unit 4 via the transmission unit 5. ing.

As shown in FIGS. 1 and 2, the body frame 1 includes a pair of front and rear longitudinally extending frames 10, 10 extending between the front and rear portions of the pair of left and right longitudinally extending frame forming pieces 10. The left and right extension frame forming pieces 11, 11 are laterally formed in a well shape.

Then, the lower end portions of a pair of left and right front frames 12, 12 are attached to the front walls of the front left and right direction extending frame forming pieces 11, and the front frames 12, 12 are raised up frontward. A horizontal frame 13 extending in the left-right direction is suspended between the upper ends of the frames 12, 12, and the same horizontal frame
A pair of left and right seat support brackets 14 and 14 project upward from the center of the pair 13, and the lower end portions of the pair of right and left rear frames 15 and 15 are attached to the rear left and right extension frame forming pieces 11. To the rear frame 15, 15
A guard frame 16, which is formed in a rectangular frame shape in a plan view, is suspended between the upper end of the horizontal frame 13 and the left and right ends of the horizontal frame 13.

Further, a front-side left-right direction extending frame forming piece.
A mounting table 17 protrudes forward from the center of the front wall of 11, and a battery 18 and a fuel tank 19 are mounted on the mounting table 17, and a rear side of the left-right extending frame forming piece 11. A front support column 20 supporting the front end of the transmission unit 5 is erected at the center, and a pair of left and right longitudinally extending frame forming pieces 10 and 10 is provided.
A pair of left and right rear supports 21, 21 for supporting the left and right rear portions of the transmission unit 5 are provided upright at the rear.

A pair of right and left motor support columns 22, 22 for supporting the motor 4 are erected at the center of the rearward left-right extension frame forming piece 11.

A PTO shaft case 23 extending in the left-right direction is suspended between the middle portions of the pair of right and left rear frames 15, 15.
The PTO shaft 24 is rotatably inserted into the PTO shaft case 23, while the front end of a lifting link 25 is pivotally supported on the outer peripheral surface of the central portion of the PTO shaft case 23 to connect the lifting link 25 to the PTO shaft.
A vertically movable cylinder 26 is provided between the middle part of the elevating link 25 and the center of the rear side frame forming piece 16c of the guard frame 16. Then, the rear end of the lifting link 25 can be moved up and down by the lifting cylinder 26, and a hitch body 27 for connecting various working machines is attached to the rear end of the lifting link 25. .

The pair of left and right running parts 2, 2 extend in the left and right direction between the front end, the center, and the rear end of the pair of left and right longitudinally extending frame forming pieces 10, 10, respectively.
The second and third wheel spindles 30, 31, 32 are laid horizontally, and each wheel spindle 30, 30,
1st, 2nd, 3rd wheels 33,3 at the left and right end of 1,32
3,34,34,35,35 to the first, second and third cylindrical axles 36,36,37,3
Installed via 7,38,38, each cylindrical axle 36,36,37,37,38,
The first, second and third transmission mechanisms 39, 39,
The right and left traveling units 2, 2 can be individually driven by interlocking connection via 40, 40, 41, 41.

Here, as shown in FIGS. 1 and 2, drive shaft case
42, 42 are formed by extending in the left-right direction, and each drive shaft case 4
Drive shafts 43, 43 are inserted through the left and right drive shafts 43, 43
The input sides of the first and third transmission mechanisms 39, 39, 41, 41 are interlockingly connected to the outer ends of the first and third transmission mechanisms 39, 39, 41, 41, respectively.

That is, the first transmission mechanism 39 is provided between the first drive sprocket 44 provided on the outer end of the drive shaft 43 and the first input sprocket 45 provided on the first cylindrical axle 36. The chain 46 is formed by winding.

The second transmission mechanism 40 includes a first cylindrical axle.
A first output sprocket 47 provided on a second axle 36 and a second cylindrical axle 37
The second transmission chain 49 is wound around the second input sprocket 48 provided at the second position.

The third transmission mechanism 41 includes a third drive sprocket 50 provided at an outer end of the drive shaft 43 and a third cylindrical axle.
The third power transmission chain 52 is wound around the third input sprocket 51 provided on the power transmission 38.

In this way, the first, second, and third wheels 33, 33, 34, 34, 35, 35 of the left and right traveling sections 2, 2 can be driven by the front wheels.

In such a configuration, the gist of the present invention is to provide a second wheel support shaft 32 for supporting a pair of left and right second wheels 34, 34,
It is attached to a pair of left and right longitudinally extending frame forming pieces 10, 10 via ground height position adjusters 53, 53 so that the ground height position can be adjusted.

That is, as shown in FIG. 3 and FIG. 4, the ground height position adjusting bodies 53, 53 have fixed side adjusting pieces 54, 54 suspended from a pair of left and right longitudinally extending frame forming pieces 10, 10, respectively. Wheel support shaft guide groove 5 with a lower end opening at the center of each fixed side adjustment piece 54, 54
5, 55 are formed in a notch shape, and each fixed side adjusting piece 54, 54 is formed.
Slots 5 for adjustment extending in the vertical direction on the front and rear sides of the
On the other hand, the movable adjustment pieces 57, 57 attached to the left and right sides of the second wheel support shaft 32 respectively have
The second wheel support shaft 32 is formed by forming bolt insertion holes 58, 58 corresponding to the holes 56, 56, and tightening and adjusting the adjustment bolt 59 inserted into the holes 56, 58, thereby adjusting the second wheel support shaft 32 to the movable side adjustment piece. 57,5
Adjust the slide position in the vertical direction as appropriate via 7
The ground clearance of the wheels 34, 34 is adjustable.

Furthermore, fine adjustment bolts 60, 60 are attached to the pair of left and right longitudinally extending frame forming pieces 10, 10 by bolt stays.
Attached to the lower end surfaces of both fine adjustment bolts 60, 60 by vertically adjusting the vertical axes of both fine adjustment bolts 60, 60, with the axis line oriented substantially vertically via 61, 61. The adjusted second wheel support shaft 32 can be finely adjusted in the vertical direction.

As shown in FIG. 1, the driving section 3 has a floor portion 65 extending in the front half of the guard frame 16, a steering column 66 standing upright on the front portion of the floor portion 65, and A wheel support shaft 67 extending vertically is inserted into the steering wheel 66, and a steering wheel is mounted on the upper end of the wheel support shaft 67.
At the same time, the lower end of the wheel support shaft 67 and the transmission section 5 described later are linked and connected via a cam mechanism 69, and a forward / reverse switching lever 180 is mounted on the lower left side wall of the steering column 66. And the forward / reverse switching lever 180
And a forward / reverse switching arm provided in a mission unit 5 described later.
181 and a connecting rod mechanism 182, and a brake pedal 183 is attached to a front portion of the floor 65, and the brake pedal 183 and a brake operation arm 166 provided in the transmission unit 5 described later are connected to the brake pedal 183. Are interlockingly connected via an interlocking wire 185.

A seat 186 is mounted on the rear side of the steering wheel 68 via the seat pivot brackets 14, 14, and various operation levers are disposed on the left and right sides of the seat 186.

That is, the shift lever 1 is located on the left side of the seat 186.
87, the transmission lever 187 is connected to a main transmission unit 97 and an auxiliary transmission unit 104 provided in the transmission unit 5 to be described later via an interlocking connection mechanism, and the work machine A lever 188 is provided, and the lever 188 is interlockingly connected to a valve mechanism (not shown) for controlling the elevating cylinder 26 via an interlocking connection mechanism.

The engine unit 4 includes an engine 76 and the engine 76
A radiator, an air cleaner, and the like (not shown) are provided near 76. As shown in FIGS. 1 and 2, the transmission 5 includes a front support 20 and a pair of left and right rear supports 2.
And a chain case 78 is interlockingly connected to the left side of the transmission section 5 while a hydrostatic stepless transmission (hereinafter referred to as “HST”) 74 for turning is provided on the right side. Are linked and connected.

As shown in FIGS. 5 to 7, the transmission unit 5 includes first to ninth shafts inside a transmission case 80.
81 to 89 are supported in parallel, the input side of the forward clutch 90a is fitted in the middle of the first shaft 81, and the end of the first shaft 81 is
The input side of the reverse clutch 90b, which is loosely fitted in the middle of the second shaft 82 via the meshing gear 91, and the hydraulic pump P
And the second shaft 82, which is the output side of the forward clutch 90a and the output side of the reverse clutch 90b, is linked to the third shaft 83 via the second meshing gear 93, and The power transmission of the reverse clutches 90a and 90b is configured to be exclusively selectable, so that the drive direction can be switched between forward and backward. 80a is a drive shaft case, and 92 is a hydraulic pump input shaft.

Here, the front / reverse clutches 90a and 90b are
Shifter spindle 160 laid on the front in the transmission case 80
At the same time, a clutch on / off shifter 161 is mounted, and the clutch on / off shifter 161 is connected with the forward clutch 90a and disengaged with the reverse clutch 90b in conjunction with the rotation of the shifter support shaft 160 in one direction. The forward clutch 90a is disengaged in conjunction with the rotation in the other direction, and the reverse clutch
90b is connected so that it can switch between forward and reverse.

A forward / reverse switching arm 162 is attached to the left end of the shifter support shaft 160.
2, a forward / reverse switching lever 180 is interlockingly connected via a connecting rod mechanism 182.

The third shaft 83 is an input shaft of the HST 74.
74a and a fourth shaft 84 which is an input shaft of the main transmission 97 via a third meshing gear 96. The fourth shaft 84 is connected to dogs 98, 98 at both ends and a central portion. A slider 100 integrally formed with the second speed driving gear 99 is slidably and non-rotatably fitted in the axial direction, while the fourth shaft 84 and the main transmission portion 97 are fitted.
The first and third speed meshing gears 101 and 102, which are always meshing, are interposed between the fifth shaft 85 and the driving shaft of the second shaft 85, and the second speed passive gear 103, which is a sliding meshing type, is fitted to the fifth shaft 85. The output rotation speed of the main transmission 97 can be switched in three stages by sliding the slider 100.

An auxiliary transmission 104 is connected in series with the main transmission 97, and the auxiliary transmission 104 is connected to the fifth shaft 85.
High and low speed meshing gears 105 and 106 are interposed between the shaft and the sixth shaft 86 as an output shaft of the auxiliary transmission portion 104, and the sixth shaft 86 is slidable in the axial direction.
By the sliding of the slider 107 fitted non-rotatably, the output rotation speed of the sub-transmission portion 104 can be shifted in two stages of high and low speeds with a neutral in between.

As described above, the forward / reverse clutches 90a, 90b
, A main transmission section 97 for three-speed shifting, and an auxiliary transmission section 104 for two-speed shifting.
Are linked in series in an interlocking manner, so that a six-step forward / backward shift operation can be finally performed.

As shown in FIG. 6, the sixth shaft 86 is linked to a seventh shaft 87 via a chain linking mechanism 108.
Left and right sun gears fitted respectively to the left and right ends of the seventh shaft 87
110,111; left and right cages 112,113 connected to the left and right drive shafts 43,43 having the same axis as the seventh shaft 87; a plurality of left and right planetary gears 114,115 respectively mounted on the left and right cages 112,113; The left and right ring gears 116 and 117 operatively connected to the output shaft 74b of the
The rotational power transmitted to the left and right sun gears 110 and 111 by the mechanical straight-line power transmission system M composed of the above-described gear type transmission and meshing gears, and the rotation power to be described later. HST of power transmission system H
The rotational power transmitted from the 74 to the left and right ring gears 116 and 117 is combined respectively, and the combined rotational power is individually transmitted to the left and right drive shafts 43 and 43 via the left and right planetary gears 114 and 115 and the left and right cages 112 and 113. I have to.

At the left end of the sixth shaft 86, a stopping brake portion 165 is provided, and the brake pedal 18 is attached to a brake operating arm 166 attached to the stopping brake portion 165.
3 is interlockingly connected via an interlocking wire 184.

As shown in FIGS. 7 and 8, the output shaft 74b of the HST 74 has a forward / reverse rotation splitting mechanism 12 which transmits the rotation speed of the output shaft 74b to the left and right ring gears 116 and 117 in a complementary manner.
0 is located on the downstream side of the turning brake unit 72 and is interlocked and connected.

The forward / reverse rotation splitting mechanism 120 is connected to the HST
The eighth shaft 88 is connected to the 74 output shaft 74b via the high / low speed switching mechanism 121.
And the eighth shaft 88 is connected to the first intermediate output gear 171,
The second intermediate input shaft 122 meshed with the first intermediate output gear 171
The left and right output gears 123 and 124 are fitted to the left and right ends of the ninth shaft 89, respectively.
The right output gear 124 and the right ring gear 117 are connected to one idle gear 123 via two idle gears (not shown) arranged in series.
Although the absolute values of the rotation speeds are equal to each other via 79, the rotation in the same direction as the ninth shaft 89 is transmitted to the left ring gear 116 while the direction opposite to the ninth shaft 89 is transmitted to the right ring gear 117. Is transmitted.

The first input shaft of the mission unit 5
One end of the shaft 81 is protruded from the left side wall of the transmission case 80, the lower end of the chain case 78 is interlockedly connected to the protruded end, and the chain case 78 is extended upward, and the upper end of the chain case 78 is extended. And the drive shaft 76a of the engine 76 are operatively connected via a first transmission belt mechanism 125, while the steering wheel 68 is operatively connected to the trunnion arm 75 of the HST 74 via a cam mechanism 69, so that the steering wheel 68 The gear ratio of the HST 74 can be changed steplessly in the forward / reverse direction according to the turning operation angle. 126 is a shifter of the main transmission unit 97, 127 is a shifter of the subtransmission unit 104, 12
8 is a front PTO shaft case for taking out power to the outside front.

Here, the turning brake unit 72 will be described. As shown in FIG.
A cylindrical input shaft 130 forming a part of the high / low speed switching mechanism 121 is spline-fitted to the output shaft 74b of the HST 74, and a wet multi-plate brake 131 is interposed between the cylindrical input shaft 130 and the transmission case 80. The wet-type multi-plate brake 131 is connected to the cylindrical input shaft 130 by disposing a shaft-shaped operating piece 132 in the vicinity of the multi-plate type brake 131 and rotating the operating piece 132 around its axis. The brake operation can be performed by sliding in the axial direction, and the lower end of the operation piece 132 projects outward from the lower part of the transmission case 80, and the brake operation arm 73 is attached to the projection end. Install,
Steering wheel 68 to the brake operation arm 73,
It is interlocked and connected via a wheel support shaft 67.

The high / low speed switching mechanism 121 includes a cylindrical input shaft.
The low-speed output gear 133 and the high-speed output gear 134 are mounted on the low-speed output gear 133, and the high-low speed switching shaft 135 is traversed close to the cylindrical input shaft 130. A low-speed input gear 136 meshing with the high-speed output gear 134 and a high-speed input gear 137 meshing with the high-speed output gear 134 are loosely fitted, and a slider 138 is freely slidable / rotatable between the input gears 136 and 137 in the axial direction. The output rotation speed of the high / low speed switching mechanism 121 can be shifted in two stages of high speed and low speed with the slider 138 sandwiching the neutral position.

The high / low speed switching shaft 135 has an output gear
The output gear 139 is meshed with the input shaft 170 mounted on the eighth shaft 88.

Further, the high / low speed switching mechanism 121 switches the speed to the high speed side in conjunction with the sub-shift operation of the shift lever 187.

Thus, the steering wheel 68
By merely turning the steering shaft to the neutral position for left and right steering, the output shaft 74b of the HST 74 can be braked by the turning brake unit 72, and the turning power transmission system H can be brought into a stopped state.
As a result, only the straight-line power transmission system M becomes operable,
The straight-moving power transmission system M can ensure good straightness of the vehicle body.

Since the turning brake 72 is provided on the output shaft 74b of the HST 74 provided on the upstream side of the turning power transmission system H, the output shaft 74b can be braked directly with a small torque. Thus, even if the capacity of the turning brake unit 72 is reduced, the power transmission of the turning power transmission system H can be reliably stopped.

Further, by turning the steering wheel 68 in one of the left and right directions from the left and right steering neutral position, the brake braking of the turning brake unit 72 is released.
The vehicle body can be turned in the rotation direction.

Therefore, the steering operability of the vehicle body, particularly the straight operability, can be improved.

Further, since the turning brake portion 72 uses the wet-type multi-plate type brake 131, the width of the turning brake portion 72 in the axial direction can be reduced.
It can be arranged in the mission case 80 without any trouble.

With the above-described structure, the power from the engine 76 is shifted in six stages in the forward and backward directions and transmitted to the left and right traveling units 2, 2, and the output rotation speed of the HST 74 is changed according to the operation angle of the steering wheel 68. Change the left and right traveling parts 2,2
, The work vehicle A can be turned in the direction in which the drive speed has decreased.

At this time, if the speed change lever 187 is operated for the sub speed change, the high / low speed switching mechanism 121 is switched to the high speed side in conjunction therewith. If you do,
The speed of the turning power transmission system H is increased, the vehicle body turns rapidly, and a turning property corresponding to the vehicle speed is obtained, so that the operation feeling of the operator can be improved.

As shown in FIG. 1, the chain case 78 is formed by extending a case body 78a in the vertical direction, and a transmission input shaft 78b is provided on an upper portion of the case body 78a.
A transmission chain 78c is wound between 78b and one end of the first shaft 81 of the transmission section 5 via sprockets 78d and 78e.

The chain case 78 has a transmission input shaft 78.
One end of b protrudes rightward from the case body 78a, and a first transmission belt mechanism 125 is interposed between the same end and the drive shaft 76a of the engine 76.

The drive shaft 76a of the engine 76 and the PT
A second transmission belt mechanism 145 is provided between the O-shaft 24 and the left end.
Is interposed.

FIGS. 8 to 10 show a second embodiment as another embodiment.
The height adjustment structure of the wheel 34 is shown.
The lowering of the second wheel 34 by the wheel raising and lowering mechanism 200 is performed while the lowering operation of the second wheel 34 by the wheel raising and lowering mechanism 200 is linked with the turning operation of the steering wheel 68. The operation width is proportional to the magnitude of the turning steering angle of the steering wheel 68.

That is, the wheel lifting / lowering mechanism 200 is provided between the pair of left and right front-rear extension frame forming pieces 10, 10.
1 is mounted via an elevating guide mechanism 201, and a link mechanism 202 is provided between the central portion of the second wheel support shaft 31 and the central portion of the left-right extending frame forming piece 11 at the front portion. Two
A wheel lifting cylinder 204 is interposed between the 02 and a pair of left and right longitudinally extending frame forming pieces 10, 10 and a cylinder supporting piece 203 provided between the middle portions of the pieces 10, 10, and the wheel lifting cylinder 204 is moved up and down by the working machine. The hydraulic pump P is connected via a control valve section 205 provided on the wheel support shaft 67.

The elevating guide mechanism 201 vertically suspends cylindrical elevating guides 206, 206 with their axes oriented in the vertical direction on a pair of left and right longitudinally extending frame forming pieces 10, 10, respectively. Wheel support shaft guide grooves 207, 207 having lower end openings are formed in the center portions of the left and right side walls in a cutout shape, and the left and right side portions of the second wheel support shaft 31 are inserted into both wheel support guide holes 207, 207, and a lifting guide body is formed. 206, 2nd wheel spindle 3 in 206
The slide members 208, 208 attached respectively to the left and right sides of the device 1 are slidably fitted in the vertical direction.

The link mechanism 202 is provided with a link stay 209 projecting rearward at the center of the left-right extension frame forming piece 11 at the front, and extending vertically at the tip end of the link stay 209. The middle part of the pair of levers 210, 210 is pivotally supported by a pivot 211 whose axis is oriented in the left-right direction to be able to swing back and forth, and protrudes upward from the upper end of each lever 210, 210 and the center of the second wheel support shaft 31. The pair of projections 212, 212 are pivotally connected and connected via a pair of left and right links 213, 213, and the lower end of each lever 210, 210 and the wheel lifting cylinder 204
Pivotally connected to the tip of 214, 215, 216 are connection pins.

The control valve section 205 has a rotary valve built therein, and is provided in a middle part of a hydraulic circuit 217 interposed between the wheel lifting cylinder 204 and the working machine lifting hydraulic pump P to provide a steering wheel. The wheel elevating cylinder 204 can be extended and contracted in proportion to the magnitude of the left-right turning steering angle 68. F is a return filter, T is a hydraulic tank, and 218 and 219 are relief valves.

Thus, the steering wheel 68
When the lever is in the neutral position, as shown in FIG.
The second wheel 34 supports the second wheel 34 at the highest position by taking an attitude in which the second wheel stands upright.

When the steering wheel 68 is turned leftward, as shown by the solid line in FIG. 10, the wheel elevating cylinder 204 is shortened, and the lever 210 is brought to the forward leaning position. The two wheels 34 are moved down.

When the steering wheel 68 is turned to the right, as shown by the dashed line in FIG.
The cylinder 204 for elevating and lowering the wheel is extended, and the lever 210 is set to the backward tilted posture. In this case as well, the second wheel 34 is made to move downward.

As described above, when the vehicle body is traveling straight, the first, second, and third wheels 33, 33, 34, 34, 35, and 35 have the same ground clearance, and Good running stability can be ensured. When the steering wheel 68 is turned to the left or right, the second wheels 34, 34 are lowered in proportion to the steering angle of the steering wheel 68. By operating, the ground height of the second wheels 34, 34 is automatically reduced.

[0070]

According to the present invention, the following effects can be obtained.

According to the present invention, the first, second and third wheels are arranged at the front, the center and the rear at an interval in the front-rear direction. The two wheels allow the height of the ground to be adjusted.

In this manner, the center second wheel is positioned beforehand so that the ground height is lower than the first and third wheels as necessary, that is, the second wheel is positioned below the first and third wheels. As a result, the surface pressure of each wheel at the time of turning becomes higher only at the center second wheel near the center of gravity of the vehicle body, and the surface pressure of the first and third wheels becomes higher. Become smaller.

As a result, the second wheel in the vicinity of the position of the center of gravity mainly turns and drives, and the first and third wheels with low contact pressure function as auxiliary wheels for guiding.

Accordingly, it is possible to minimize the occurrence of skidding or mud-pulling (mud pushing) of the field by the first and third wheels, thereby preventing the field from being roughened and improving the turning performance. Can be.

According to the second aspect of the present invention, the pair of right and left running parts is provided with the first, second, and third wheel support shafts extending in the left and right directions at the front, center, and rear of the body frame, respectively. Then, first, second, and third wheels are respectively attached to left and right end portions of each wheel support shaft via first, second, and third cylindrical axles,
Each cylindrical axle is interlocked with the mission section to enable the left and right traveling sections to be individually driven, and a second wheel spindle supporting a pair of left and right second wheels is connected to the body frame via a ground height position adjuster. The height of the ground is adjustable.

In this manner, the height of the second wheel support shaft is adjusted via the ground height position adjuster, so that the left and right ends of the second wheel support shaft are adjusted via the second cylindrical axle. The ground height of the pair of left and right second wheels mounted can be simultaneously adjusted, and the work of adjusting the ground height of the second wheels can be performed quickly and reliably.

According to the third aspect of the present invention, the pair of right and left running parts are provided with first, second, and third wheels at front, center, and rear portions of the left and right sides of the body frame with an interval in the front-rear direction. The second wheel at the center is freely movable up and down by a wheel elevating mechanism, and the lowering operation of the second wheel by the wheel elevating mechanism is linked to the turning operation of the steering wheel.

In this way, when traveling straight, the first
The ground heights of the second and third wheels are set to be substantially the same so that good running stability during straight running is ensured, and at the time of turning, the second wheel is lowered in conjunction with turning operation by the steering wheel. So that it can be done.

Accordingly, the surface pressure of each wheel at the time of turning becomes higher only at the second wheel in the center near the center of gravity of the vehicle body, and the surface pressure of the first and third wheels becomes smaller. As a result, the same effect as described above can be obtained.

When the steering wheel is switched from the turning operation to the straight-ahead operation, the second wheel rises in conjunction therewith, and the ground clearance becomes substantially the same as the first and third wheels. The running stability at the time can be satisfactorily secured.

In the present invention, the lowering width of the second wheel by the wheel lifting / lowering mechanism is proportional to the magnitude of the turning steering angle of the steering wheel.

In this manner, as the turning angle of the steering wheel increases, the descending operation width of the second wheel can be automatically increased, and the contact pressure that the second wheel bears is increased. At the same time, the ground pressure that the first and third wheels bear is reduced, and the first and third wheels during turning are reduced.
Sliding by the third wheel and burying (mud pushing) in the field can be reduced as much as possible, and the vehicle body can be smoothly and rapidly turned, so that the turning performance can be improved.

When the steering wheel is operated straight ahead, the ground heights of the second wheel and the first and third wheels can be made substantially the same, and the running stability during straight running can be ensured well. it can.

[Brief description of the drawings]

FIG. 1 is a side view of a six-wheel working vehicle according to the present invention.

FIG. 2 is a cross-sectional plan view of a vehicle body frame and a traveling unit.

FIG. 3 is an explanatory side view of a mounting portion of a second wheel.

FIG. 4 is an explanatory sectional side view of a mounting portion of the second wheel.

FIG. 5 is an explanatory diagram of a left side view of a cross section of a transmission unit.

FIG. 6 is a cross-sectional plan view of a transmission unit showing a straight-moving power transmission system.

FIG. 7 is a cross-sectional plan view of a transmission unit showing a turning power transmission system.

FIG. 8 is an explanatory side view of a mounting portion of a second wheel as a second embodiment.

FIG. 9 is an explanatory cross-sectional rear view of a mounting portion of the second wheel.

FIG. 10 is a left side sectional view of a transmission unit.

[Explanation of symbols]

 A Work vehicle 1 Body frame 2 Running part 3 Driving part 4 Motor unit 5 Transmission unit

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masakazu Komatsu 1-32 Chaya-cho, Kita-ku, Osaka-shi, Osaka F-term in Yanmar Agricultural Machinery Co., Ltd. 2B041 AA08 AB05 AC20 BA02 2B043 AA04 AB08 AB17 BA02 BB01 DC03 DC10

Claims (4)

[Claims] 1. A six-wheel working vehicle in which a pair of left and right traveling units are interlockedly connected to a prime mover unit via a transmission unit, and each transmission unit is individually driven by the transmission unit. The six wheels are characterized in that first, second, and third wheels are arranged at an interval in a front-rear direction at a portion, a center portion, and a rear portion, and the height of the second wheel at the center portion is adjustable. Working vehicle. 2. A pair of right and left running parts are provided at a front part, a center part, and a rear part of a body frame, and extend in left and right directions, respectively.
The second and third wheel axles are mounted horizontally, and the first, second and third wheels are attached to the left and right ends of the respective wheel axles via the first, second and third cylindrical axles, respectively. Each cylindrical axle is linked to the mission section to enable the left and right traveling sections to be individually driven. A second wheel support shaft supporting a pair of left and right second wheels is connected to the body frame via a ground height position adjuster. The six-wheeled work vehicle according to claim 1, wherein the vehicle is mounted so as to be adjustable in height above the ground. 3. A six-wheeled working vehicle in which a pair of left and right traveling units are connected to a prime mover unit via a transmission unit and each traveling unit is individually driven by the transmission unit. The first, second, and third wheels are arranged at the front, center, and rear portions of the left and right sides of the body frame with an interval in the front-rear direction. And a lowering operation of the second wheel by the wheel lifting / lowering mechanism in conjunction with a turning operation of the steering wheel. 4. The six-wheel working vehicle according to claim 3, wherein a lowering operation width of the second wheel by the wheel lifting / lowering mechanism is proportional to a magnitude of a turning steering angle of the steering wheel.