Work vehicle

Abstract

To provide a single brake switch having various functions on a work vehicle such as a tractor.SOLUTION: A work vehicle is configured to comprise left and right brake devices 10 which brake respective left and right rear wheels 9, a steering wheel 3 which operates a direction of travel, and left and right switch operation parts 24 which are provided on left and right sides sandwiching a steering shaft 30 of the steering wheel 3, and to operate the left and right brake devices 10 on a corresponding side for a prescribed time and / or with a prescribed strength predetermined by operating either of the left and right switch operation parts 24 once.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to work vehicles such as tractors. [Background technology]

[0002] A known work vehicle includes left and right brake devices that independently brake the left and right rear wheels, a steering wheel that operates the steering device to steer the vehicle body, a motor connected to the steering wheel, a positioning device that measures the position of the vehicle body, and a control unit that controls the motor so that the vehicle automatically travels straight along a set planned travel route. Furthermore, a single-brake switch that activates either the left or right brake device has been disclosed (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-185781 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the description of the operation of such a one-side brake switch is vague, and its function and action are not clear.

[0005] The present invention takes into consideration the problems with conventional single-brake switches and has as its object to provide a work vehicle equipped with left and right switch operating sections that have a variety of functions. [Means for solving the problem]

[0006] The first aspect of the present invention is Left and right brake devices that brake the left and right rear wheels, respectively; A steering wheel to control the direction of travel, left and right switch operation units provided on the left and right sides of the steering shaft of the steering wheel, This work vehicle is characterized in that when the driver operates either the left or right switch operating unit once, the control unit activates the left or right brake device on the corresponding side for a predetermined period of time and / or with a predetermined strength.

[0007] The second aspect of the present invention is In the first work vehicle of the present invention, the left and right switch operation units are provided in a location near the steering wheel so that they do not rotate together with the steering wheel and so that the driver can operate the left and right switch operation units while holding the steering wheel.

[0008] The third aspect of the present invention is This is a second work vehicle of the present invention, which is provided with a dial that can adjust the specified time and / or specified strength for activation of the left and right brake devices when either the left or right switch operating unit is operated once.

[0009] The fourth aspect of the present invention is a first counter that counts the number of times the left switch operation unit and the right switch operation unit of the left and right switch operation units are alternated; When the value of the first counter exceeds a predetermined value, the predetermined time and / or the predetermined strength in a subsequent operation is changed to be shorter and / or weaker than before, This is a third work vehicle of the present invention, in which after a predetermined period of time has passed since either the left or right switch operating unit is operated and neither is operated, the value of the first counter is reset and the predetermined period of time and / or predetermined strength is restored to its original state.

[0010] The fifth aspect of the present invention is a second counter for counting the number of operations of each of the left and right switch operation units; When the value of the second counter exceeds a predetermined value determined for each, the predetermined time and / or the predetermined strength in a subsequent operation of the corresponding left or right switch operation unit on the side where the value of the second counter exceeds is changed to be longer and / or stronger than before, Thereafter, if the operation of the left switch operation unit and the operation of the right switch operation unit of the left and right switch operation units are reversed, the value of the second counter is reset and the specified time and / or specified strength are restored to their original states.This is a fourth work vehicle of the present invention.

[0011] The sixth aspect of the present invention is a steering angle sensor 12 for detecting the operation angle of the steering wheel; The larger the detection value of the steering angle sensor 12, the longer and / or stronger the predetermined time and / or the predetermined strength are changed to be than before, Thereafter, when the operation angle becomes equal to or smaller than a predetermined angle, the predetermined time and / or the predetermined strength is restored to its original state.

[0012] The seventh aspect of the present invention is a direction sensor for detecting the direction of operation of the steering wheel; In a sixth work vehicle of the present invention, when the left or right switch operation unit that is opposite to the direction detected by the direction sensor is operated, the operation instruction of the left or right switch operation unit is invalidated by the control unit.

[0013] The eighth aspect of the present invention is The left and right brake pedals are provided to individually operate the left and right brake devices, a left and right pedal sensor for detecting when one of the brake pedals is depressed; In a work vehicle according to a seventh aspect of the present invention, when either the left or right brake pedal is depressed, the operation instructions of the left or right switch operation unit are invalidated by the control unit.

[0014] The ninth aspect of the present invention is An automatic brake device is provided that operates the left and right brake devices individually, A single main brake pedal is provided to simultaneously operate the left and right brake devices, In an eighth aspect of the work vehicle of the present invention, the control unit determines that the vehicle is turning when the detection value of the steering angle sensor is greater than a predetermined threshold value, invalidates instructions from the left and right switch operation units, and activates the auto brake device.

[0015] The tenth aspect of the present invention is The left and right brake pedals are provided to individually operate the left and right brake devices, In a work vehicle according to an eighth aspect of the present invention, the control unit determines that a turn is occurring when the detection value of the steering angle sensor is greater than a predetermined threshold value, and invalidates instructions from the left and right switch operation units.

[0016] An eleventh aspect of the present invention is In the work vehicle of an eighth aspect of the present invention, when traveling on a road, the operation instructions of the left and right switch operation units are invalidated by the control unit.

[0017] The twelfth aspect of the present invention is This is a work vehicle of any one of the first to eleventh inventions, wherein the left and right switch operating units are momentary switches, the specified time is not predetermined, and the left and right brake devices operate while the switches are continuously pressed.

[0018] The thirteenth aspect of the present invention is In any one of the work vehicles of the present invention Nos. 2 to 11, the left and right switch steering units are switches that use rod-shaped levers, and the left lever is of a type that executes the operation once by tilting it to the left and automatically returns to its original position when released, and the right lever is of a type that executes the operation once by tilting it to the right and automatically returns to its original position when released. [Effects of the Invention]

[0019] According to the present invention, when a work vehicle travels in a straight line, fine adjustment of the traveling direction can be easily performed. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is a side view of a work vehicle according to an embodiment of the present invention; [Figure 2] FIG. 10 is a simplified plan view showing the control flow of the hydraulic system of the work vehicle. [Figure 3] FIG. 1 is a block diagram showing the control flow of the work vehicle; [Figure 4] A perspective view of the driver's seat and surrounding area of ​​the work vehicle DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0022] 1 is a configuration diagram of a tractor as an example of a work vehicle according to an embodiment of the present invention. In the following, the direction of travel of the tractor is used as the reference for determining front, rear, left and right.

[0023] In Figure 1, reference numeral 1 denotes the body of the work vehicle of this embodiment, and reference numeral 2 denotes a positioning device such as a GNSS receiver provided above and in front of the body 1. Reference numeral 3 denotes a steering wheel operated by the driver, below which a steering motor 5 is provided. Reference numeral 30 denotes a steering shaft of this steering wheel 3.

[0024] An inclination sensor 4 is attached to the side of the vehicle body 1 to detect the degree of inclination of the vehicle body 1. Furthermore, a control unit 7 is located below the operation panel 6 and has a travel route memory unit 7a in which planned travel route data for the field is pre-recorded.

[0025] 2, the vehicle body 1 has left and right front wheels 8L, 8R and left and right rear wheels 9L, 9R, and left and right brake devices 10L, 10R are attached to the left and right rear wheels 9L, 9R, respectively. The left and right brake devices 10L, 10R can be braked independently.

[0026] The front wheels 8L, 8R are rotated by a steering device 11 such as a steering cylinder, and the steering device 11 rotates the front wheels 8L, 8R in accordance with the amount of rotation of the steering wheel 3. The amount of rotation of the front wheels 8L, 8R (the amount of operation of the steering device 11) is detected by a steering angle sensor 12.

[0027] Fig. 2 is a schematic plan view showing the control flow of the hydraulic system, etc., and Fig. 3 is a configuration diagram showing the control flow. In these figures, the output of an engine 16 is connected and disconnected by a forward / reverse clutch 17, and the output is speed-changed by a main transmission unit 18 and further speed-changed by an auxiliary transmission unit 20, and the output is transmitted to rear wheels 9L, 9R. Here, 15 is a front wheel operating gear, and 21 is a rear wheel operating gear.

[0028] As described above, the left and right front wheels 8L, 8R are turned by the steering device 11, and the steering angle is detected as the operation amount of the steering device 11 by the steering angle sensor 12 and transmitted to the control unit 7. In addition, the output of the auxiliary transmission unit 20 is also transmitted to the front wheels 8L, 8R via the 4WD clutch 19. Furthermore, reference numeral 13 denotes a vehicle speed sensor which detects the output of the auxiliary transmission unit 20 to detect the vehicle speed.

[0029] Furthermore, left and right brake devices 10L and 10R are attached to the left and right rear wheels 9L and 9R, respectively, and can brake the rear wheels 9L and 9R independently, but the left and right brake devices 10L and 10R are hydraulically controlled by left and right brake cylinders 23L and 23R, respectively.

[0030] Further, 22R is a right brake pedal for mechanically braking the right brake device 10R, and 22L is a left brake pedal for mechanically braking the left brake device 10L.

[0031] Furthermore, these left and right brake cylinders 23L, 23R are controlled by a hydraulic system 14 as will be described below.

[0032] As a typical example, let's assume that a work vehicle is traveling straight in a field. That is, the current position data of the vehicle 1 is constantly transmitted to the control unit 7 from the positioning device 2 attached to the vehicle body 1, for example, from a GNSS receiver. The control unit 7 is provided with a travel route memory unit 7a that stores in advance the travel route that the work vehicle should travel. The control unit 7 compares this position data with the travel route data, and if there is any discrepancy, it sends a signal to the motor 5 that drives the steering device 11 to rotate the front wheels 8L, 8R and control the vehicle to return to the travel route. In this way, straight-ahead travel control is performed.

[0033] 2, 3, and 4, 24L and 24R are one-sided brake switches that are an example of a switch operating unit of the present invention, and each can be turned on and off independently. When the one-sided brake switches 24L and 24R are operated, a switch signal is input to the control unit 7, and the control unit 7 sends a command signal to the hydraulic system 14 in response to the signal, causing the left brake device 10L or the right brake device 10R to apply braking.

[0034] That is, for example, when the vehicle body 1 rotates to the right, a drive signal is sent to the right brake solenoid 14aR in the hydraulic system 14 in Fig. 2. As a result, the right single brake valve 14bR moves to the center, transmitting hydraulic pressure from the pump 14h to the right brake cylinder 23R, which then applies the brake to the right brake device 10R. As a result, the vehicle body 1 rotates to the right.

[0035] Furthermore, when the control unit 7 sends a drive signal to the left brake solenoid 14aL in the hydraulic system 14, the left single brake valve 14bL moves to the center and transmits hydraulic pressure from the pump 14h to the left brake cylinder 23L, which then applies the brake to the left brake device 10L. As a result, the vehicle body 1 rotates to the left. Reference numeral 14g denotes a relief valve. Reference numeral 14c denotes a dual brake valve for applying both the left and right brakes, 14d denotes a single brake valve (the drawing shows the single brake state), and 14e denotes a dual brake solenoid, making it possible to select between dual brakes and single brakes. It is desirable that the control unit 7 can use the proportional valve control 14f to change the magnitude of the hydraulic pressure and appropriately change the magnitude of the braking force of the left and right single brake devices 10L, 10R.

[0036] As shown in Fig. 4, the single brake switches 24L, 24R are provided on the left and right sides of the steering shaft 30 of the steering wheel 3 at the driver's seat. Furthermore, the left and right single brake switches 24L, 24R are provided in locations that do not rotate together with the steering wheel 3 and are located near the steering wheel 3 so that the driver can operate the left and right single brake switches 24L, 24R while gripping the steering wheel 3, making them easy for the driver to operate.

[0037] If the single brake switches 24L, 24R rotate together with the steering wheel 3, for example if the single brake switches 24L, 24R are fixed to the steering wheel 3 itself, the driver may confuse the left and right of the single brake switches 24L, 24R while turning the steering wheel 3, but since they do not rotate together, such erroneous operation can be prevented.

[0038] Furthermore, the left and right single-brake switches 24L, 24R are switches that use rod-shaped levers, and the left lever 24L is a type that is operated once by tilting it to the left, as described below, and automatically returns to its original position when released, while the right lever 24R is operated once by tilting it to the right, and automatically returns to its original position when released.

[0039] For example, when turning left, the driver can tilt the rod-shaped single brake switch 24L located on the left side to the left with their thumb, which unifies the driver's sense of direction to the left and makes it easier to operate. Also, if the type requires the driver to lift the switch to the right after it has fallen over, the driver will get confused about which side is right and which is why the switch is designed to automatically return to its original position.

[0040] Furthermore, by operating either the left or right single brake switch 24L, 24R once, the left or right brake device 10L, R on the corresponding side can be activated for a predetermined time and / or with a predetermined strength.

[0041] Here, "one operation" means an operation that actually causes the brake devices 10L, R to operate continuously once, regardless of the type of switch or the manner of operation. In other words, whether the switch type is momentary, alternator, push-in, flip-down, or toggle, it means an operation that actually causes the brake devices 10L, R to operate continuously once.

[0042] The predetermined time is the length of time for which the brakes are continuously operating, and the predetermined strength is the strength of the braking force of the brake devices 10L, R during the continuous operation.

[0043] For example, if the single brake switches 24L, 24R are the aforementioned automatic return rod-shaped levers, a single operation means pushing the rod-shaped lever down once with your thumb, and then releasing your thumb causes the rod-shaped lever to automatically return to its original position. In this case, regardless of how long you hold down the lever with your thumb, the brake devices 10L, 10R will operate continuously for a predetermined period of time. Furthermore, regardless of how hard you push down the rod-shaped lever or how far you move it, the brake devices 10L, 10R will operate with a predetermined force.

[0044] Therefore, in this case, if the traveling vehicle body 1 tilts slightly to the right while traveling straight, the driver pushes the lever of the left single brake switch 24L to the left with his thumb, and if this does not sufficiently correct the course, he pushes the lever, which automatically returns to its original position, to the left again. It is also possible to push it further repeatedly. In this way, fine adjustments to the traveling direction can be made.

[0045] In Fig. 3, reference numeral 31 denotes a dial that can adjust the predetermined time and / or predetermined strength for actuation of the left and right brake devices 10L, 10R when either the left or right single brake switch 24L, 24R is operated once. By operating this dial 31, data in the predetermined time / strength memory unit 32 of the control unit 7 can be changed.

[0046] 3, reference numeral 33 denotes a first counter that counts the number of times that the operation of the left single brake switch 24L and the operation of the right single brake switch 24R are alternated between. That is, as described above, even if the left single brake switch 24L is turned on several times, the count value of the first counter 33 does not increase, but if the right single brake switch 24R is subsequently turned on even once, the count value will be increased by one.

[0047] If the value of this first counter 33 exceeds a predetermined value, the predetermined time and / or predetermined strength in a single operation thereafter is changed to be shorter and / or weaker than before.

[0048] For example, if the left single brake switch 24L and the right single brake switch 24R are alternately switched three times, it can be determined that the predetermined time is too long or the predetermined strength is too strong, and the predetermined time is changed to be shorter and / or weaker than before, so that the vehicle is quickly returned to a straight trajectory.

[0049] Furthermore, after a predetermined period of time has passed since either the left or right brake switch 24L, 24R was operated and no operation of either switch, the value of the first counter 33 is reset and the predetermined period of time and / or the predetermined strength is restored to its original state. This is to deal with cases where the condition of the mud in the field is partially different from the standard condition.

[0050] In Fig. 3, 34 denotes a second counter that counts the number of times each of the left and right single brake switches 24L, 24R is operated. When the value of this second counter 34 exceeds a predetermined value, the predetermined time and / or predetermined strength for each subsequent operation of the corresponding left or right single brake switch 24L, 24R on the side that exceeded the value is changed to be longer and / or stronger than before.

[0051] That is, for example, as described above, each time the left single brake switch 24L is pressed, the count value of the second counter 34 increases. When a predetermined number of times, for example, three times, is reached, the predetermined time and / or predetermined strength for each subsequent operation of the left single brake switch 24L is changed to be longer and / or stronger than before. The reason that trajectory correction is not possible without multiple operations is because it is assumed that the predetermined time is too short or the strength is too weak for that location. The predetermined time and predetermined strength are based on the assumption that the field conditions are standard, so they need to be partially changed. The same applies to the right single brake switch 24R.

[0052] Furthermore, after such a change, if the operation of the left and right single brake switches 24L, 24R is reversed, the value of the second counter 34 is reset and the specified time and / or specified strength is restored to its original state.

[0053] In FIG. 3, a steering angle sensor 12 is provided to detect the operation angle of the steering wheel 3, and the larger the detection value of the steering angle sensor 12, the longer and / or stronger the predetermined time and / or predetermined strength is changed from before.

[0054] In other words, when the operating angle of the steering wheel 3 is large, there is a possibility that the deviation of the traveling vehicle body 1 from the trajectory is large in many cases, so in such cases, the specified time and / or specified strength of a single operation of the left and right single brake switches 24L, 24R is changed to be longer and / or stronger than before in order to quickly return to the trajectory.

[0055] Thereafter, when the operation angle becomes equal to or smaller than a predetermined angle, it is estimated that the trajectory has approached a straight line, and the predetermined time and / or the predetermined strength are controlled to return to their original state.

[0056] In FIG. 3, 35 is a direction sensor that detects the direction of operation of the steering wheel 3. When the left or right single brake switch 24L, 24R is operated in a direction different from the direction detected by this direction sensor 35, the operation instruction of the left or right single brake switch 24L, 24R is invalidated by the control unit 7.

[0057] Whether the vehicle is being driven manually or automatically, the driver is less likely to make a mistake with the steering wheel 3 in terms of left and right direction than the one-side brake switches 24L and 24R, so it is desirable for the driver to ignore the one-side brake switches 24L and 24R, which are more likely to be confused.

[0058] The steering angle sensor 12 can also be used as the direction sensor 35.

[0059] 2 and 4, as described above, left and right single brake pedals 22L, 22R are provided to individually operate the left and right brake devices 10L, 10R, but left and right pedal sensors 36L, 36R are also provided to detect when the single brake pedals 22L, 22R are depressed (see FIG. 3), and when either the left or right single brake pedal 22L, 22R is depressed, the operation command of the left and right single brake switches 24L, 24R is invalidated by the control unit 7.

[0060] This is to avoid confusion between the operation of the mechanically connected one-side brake pedals 22L, 22R and the electrical indication of the one-side brake switches 24L, 24R.

[0061] In Fig. 3, 37 denotes an automatic brake device that individually operates the left and right brake devices 10L and 10R, and is equipped with one main brake pedal (not shown) that simultaneously operates the left and right brake devices 10L and 10R.

[0062] When the detection value of the steering angle sensor 12 is greater than a predetermined threshold, the control unit 7 determines that the vehicle is turning, invalidates the instructions from the left and right single brake switches 24L, 24R, activates the auto brake device 37, and individually activates the corresponding left and right brake devices 10L, 10R to ensure smooth turning.

[0063] In addition, one main brake pedal is used when driving on the road, but since there is only one pedal, more space can be secured for the feet.

[0064] 2 and 4, as described above, the left and right single brake pedals 22L, 22R are provided to individually operate the left and right brake devices 10L, 10R, but when the detection value of the steering angle sensor 12 is greater than a predetermined threshold, the control unit 7 determines that the vehicle is turning, invalidates the instructions from the left and right single brake switches 24L, 24R, and assists the turning by operating the single brake pedals 22L, 22R.

[0065] When traveling on the road, the operation instructions of the left and right brake switches 24L, 24R are invalidated by the control unit 7. Braking for the purpose of fine adjustment is unnecessary when traveling on the road, and may actually cause confusion.

[0066] In addition, the one-side brake switches 24L, 24R of the present invention may be momentary switches, and in this embodiment, the specified time is not predetermined, and the left and right brake devices 10L, 10R are operated while the switch is continuously pressed.

[0067] Alternatively, the single brake switches 24L and 24R can be seesaw type switches. In this case, care must be taken not to confuse the left and right. The installation position of the switches is preferably on the lever guide or armrest.

[0068] Furthermore, a one-side brake restricting switch (not shown) may be provided to restrict the operation of the one-side brake switches 24L, 24R. By pressing this one-side brake restricting switch, it is possible to prevent the one-side brake switches 24L, 24R from being operated accidentally.

[0069] A monitor lamp or meter panel is provided to display the operating status of this one-side brake restriction switch, and when the one-side brake restriction switch is on and there is a restriction, it flashes, and when it is off, it goes out. Or it can display the opposite.

[0070] Such a one-brake restricting switch may be automatically activated to restrict operation of the one brake when certain conditions are met, such as the vehicle speed, the type of driving mode, the position of the auxiliary gearbox, etc. In other words, this is to automatically disable operation of the one brake in a dangerous situation.

[0071] In this case, if the one-side brake restriction switch is a momentary switch, it is desirable that when the restriction is automatically applied, the state be clearly visible from the outside.

[0072] In the above-described embodiment, when traveling in a farm field, both automatic traveling using a positioning device and manual traveling can be applied within the applicable range.

[0073] Furthermore, the work vehicle according to the present invention is not limited to tractors and can also be applied to other rice transplanters and the like. [Industrial Applicability]

[0074] The present invention is ideal for tractors because it can provide a work vehicle equipped with a single brake switch that can perform a variety of functions. [Explanation of symbols]

[0075] 1 Running vehicle 2. Positioning Device 3 Steering wheel 4 Tilt Sensor 5 motors 6 Operation panel 7 Control Unit 8R,L Left and right front wheels 9R,L Left and right rear wheels 10R,L left and right brake device 11 Steering device 12 Steering angle sensor 13 Speed ​​sensor 14 Hydraulic system 22R,L left and right brake pedals 23R,L left and right brake cylinders 24R,L Single brake switch 30 Steering shaft 31 Dial 32 Predetermined time / predetermined strength memory section 33 Counter 1 34 Second Counter 35 Direction Sensor 36 Left and right pedal sensors 37 Automatic braking device

Claims

1. Left and right brake devices that brake the left and right rear wheels, respectively; A steering wheel to control the direction of travel, left and right switch operation units provided on the left and right sides of the steering shaft of the steering wheel, A work vehicle characterized in that when the driver operates either the left or right switch operation unit once, the control unit activates the left or right brake device on the corresponding side for a predetermined period of time and / or with a predetermined strength.

2. 2. The work vehicle according to claim 1, wherein the left and right switch operation units are provided in locations near the steering wheel so that they do not rotate together with the steering wheel and so that the driver can operate the left and right switch operation units while holding the steering wheel.

3. 3. The work vehicle according to claim 2, further comprising a dial that can adjust the predetermined time and / or predetermined strength for activation of the left and right brake devices when either the left or right switch operation unit is operated once.

4. a first counter that counts the number of times that the left switch operation unit and the right switch operation unit of the left and right switch operation units are alternated; When the value of the first counter exceeds a predetermined value, the predetermined time and / or the predetermined strength in a subsequent operation is changed to be shorter and / or weaker than before, 4. The work vehicle according to claim 3, wherein after a predetermined period of time has elapsed since either the left or right switch operation unit was operated and no operation of either unit has been performed, the value of the first counter is reset and the predetermined period of time and / or the predetermined strength is restored to its original state.

5. a second counter for counting the number of operations of each of the left and right switch operation units; When the value of the second counter exceeds a predetermined value determined for each, the predetermined time and / or the predetermined strength in a subsequent operation of the corresponding left or right switch operation unit on the side where the value of the second counter exceeds is changed to be longer and / or stronger than before, 5. The work vehicle according to claim 4, wherein when the operation of the left switch operation unit and the operation of the right switch operation unit of the left and right switch operation units are subsequently switched, the value of the second counter is reset and the specified time and / or specified strength is restored to its original state.

6. a steering angle sensor for detecting an operation angle of the steering wheel; The larger the detection value of the steering angle sensor, the longer and / or stronger the predetermined time and / or the predetermined strength are changed to be than before, 6. The work vehicle according to claim 5, wherein thereafter, when the operation angle becomes equal to or smaller than a predetermined angle, the predetermined time and / or the predetermined strength is restored to its original state.

7. a direction sensor for detecting the direction of operation of the steering wheel; 7. The work vehicle according to claim 6, wherein when a left or right switch operation unit opposite to the direction detected by the direction sensor is operated, the operation instruction of the left or right switch operation unit is invalidated by the control unit.

8. The left and right brake pedals are provided to individually operate the left and right brake devices, a left and right pedal sensor for detecting when one of the brake pedals is depressed; 8. The work vehicle according to claim 7, wherein when either the left or right brake pedal is depressed, the control unit invalidates operation instructions from the left or right switch operation unit.

9. An automatic brake device is provided that operates the left and right brake devices individually, A single main brake pedal is provided to simultaneously operate the left and right brake devices, 9. The work vehicle according to claim 8, wherein the control unit determines that the vehicle is turning when the detection value of the steering angle sensor is greater than a predetermined threshold value, invalidates instructions from the left and right switch operation units, and activates the automatic brake device.

10. The left and right brake pedals are provided to individually operate the left and right brake devices, 9. The work vehicle according to claim 8, wherein the control unit determines that the vehicle is turning when the detection value of the steering angle sensor is greater than a predetermined threshold value, and invalidates instructions from the left and right switch operation units.

11. 9. The work vehicle according to claim 8, wherein when traveling on a road, the operation instructions of the left and right switch operation units are invalidated by the control unit.

12. 12. The work vehicle according to claim 1, wherein the left and right switch operation units are momentary switches, the predetermined time is not determined in advance, and the left and right brake devices are activated while the switches are continuously pressed.

13. 12. A work vehicle according to any one of claims 2 to 11, wherein the left and right switch steering units are switches that use rod-shaped levers, the left lever being of a type that executes the operation once by tilting it to the left and automatically returns to its original position when released, and the right lever being of a type that executes the operation once by tilting it to the right and automatically returns to its original position when released.

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