JP5125260B2 - Tractor - Google Patents

Description

The present invention relates to a tractor. In particular, the present invention relates to a work implement lifting apparatus that automatically controls the work implement to be raised or lowered in connection with a turning operation.

Conventionally, an agricultural tractor, for example, when a rotary tiller is attached and the body is turned while reaching the end of the field while plowing the field, the rotary tiller is related to the turning operation of the operator. 2. Description of the Related Art A work machine automatic raising / lowering control device during turning that rises to a non-working position with a height that does not collide with an obstacle is known as a known technique. For example, Japanese Patent Laid-Open No. 11-98901 (see Patent Document 1) discloses a configuration in which when the steering wheel is steered and the tractor is turned, the working machine is automatically raised to the non-working position by the lifting control means. Has been. The work machine that is automatically lifted is configured to be lowered to a lower work position by a lowering operation of the lift lever after the turn is completed.

And, as disclosed in Japanese Patent Laid-Open No. 1-1141505 (see Patent Document 2), it is determined that the tractor starts to turn when the front wheel turning angle exceeds a predetermined value, as is apparent from the accompanying drawings and the description. In addition, an automatic raising mechanism for raising the ground work machine is provided, and an automatic lowering mechanism for lowering the ground work machine when the turning angle of the front wheel is returned to a predetermined value or less is judged to be the end of the turning operation. The configuration is shown. The known technology automatically raises the ground working machine mounted on the tractor to the non-working position in relation to the turning operation, and automatically lowers to the original working position when it is detected that the turning operation is completed. It has become.
Japanese Patent Laid-Open No. 11-98901 JP-A-1-141505

The above-described conventionally known automatic lifting / lowering control device for a working machine during turning (mainly, see Patent Document 2) detects that the working machine is automatically lifted with the start of the turning operation and the turning operation is finished. However, since the automatic lowering control works and the work machine automatically descends, it is convenient to save the labor of the lifting operation, but there is a problem with danger.

Specifically, work implements attached to tractors, such as rotary tillers, remove grass wrapped around a tilling sword or tilling shaft when the operator is manually raised to the height of the non-working position. There are many cases of cleaning work or other maintenance work such as parts replacement. At that time, when the tractor is moved carelessly and the handle is turned, the automatic lifting and lowering control device for the work implement during turning works to return the handle. Then, there is a risk that the work implement will descend unexpectedly due to the automatic lowering mechanism. Therefore, the invention according to claim 1 of the present application is that after the end of the turning operation is determined, for example, when the operator has raised the working machine to the height of the non-working position manually. However, it is assumed that the maintenance work can be safely performed as a configuration in which the automatic lowering mechanism cannot perform the automatic lowering.

When the tractor reaches the end of the field, it may want to perform cleaning and maintenance such as removal of mud and grass from the rotary tillage device in the middle of work, but usually the completion of the turning operation is detected Then, since the work implement is immediately lowered by the automatic lowering mechanism, a dangerous state often occurs. In view of this, the invention of claim 2 of the present application is intended to be safe by adopting a configuration in which the work implement cannot be automatically lowered after a preset time has elapsed after the work implement is automatically raised in connection with the turning operation. .

Since the cleaning and maintenance performed by raising the tractor work machine to the non-working position is usually performed after stopping, the invention of claim 3 of the present application claims that the work machine automatically moves up and down during turning. Even when the work equipment is automatically lifted using the control device, when the turning operation is finished, if the tractor is stopped, the operation of the automatic lowering mechanism is restricted and the work equipment is not lowered to ensure safety. Is.

In order to solve the above-mentioned problem, the present invention is characterized in that the work machine (2) is provided on the tractor (1) so that it can freely move up and down, and the cutting angle of the front wheel (3) is greater than a set value. When this happens, an automatic raising mechanism (4) for raising the work machine (2) is provided, and an automatic lowering mechanism for lowering the work machine (2) when the turning angle of the front wheel (3) becomes less than a set value. In the tractor at the time of turning provided with (5), the work machine (2) in which the ascending movement is manually performed, the automatic lowering mechanism (5) even after the end of the turning operation is determined. a configuration that can not be auto down by,
A controller 25 is provided connected to a monitor (30), and the state of automatic lifting / lowering of the work machine (2) can be confirmed on a television screen,
The tractor is characterized in that the condition that the automatic lowering by the automatic lowering mechanism (5) is prohibited can be canceled by a touch operation on the screen of the monitor (30) .

Normally, when the work implement (2) is raised by an operation other than the automatic lift mechanism (4), maintenance work such as cleaning to remove mud and entangled grass attached to the cultivating sword or cultivator shaft or replacement of parts is required. There are many cases to do. Accordingly, when the handle of the tractor (1) is turned, the automatic lifting / lowering control device for the working machine at the time of turning works, and when the handle is returned, the working machine (2) is lowered unexpectedly by the automatic lowering mechanism. . In such a case, the invention according to claim 1 is that the work machine (2) is moved after the end of the turning operation is determined when the operator has manually raised the non-working position. However, as a configuration in which automatic lowering by the automatic lowering mechanism (5) is not possible, maintenance work and the like can be safely performed.

Next, in the invention described in claim 2, the work machine (2) raised by the automatic raising mechanism (4) cannot be automatically lowered by the automatic lowering mechanism (5) when a set time elapses after being raised. The tractor according to claim 1 is configured.

For example, when the tractor (1) reaches the end of the field in the middle of plowing with the rotary tiller, there is a case where it is desired to perform cleaning and maintenance to remove mud and grass of the rotary tiller. At that time, the invention according to claim 2 is configured such that the work implement is lifted using the automatic work implement lift control device during turning, and the work implement (2) cannot be automatically lowered when a preset time has elapsed. Therefore, automatic lowering does not occur and maintenance work can be performed safely.

Next, in the invention described in claim 3, the work machine (2) lifted by the automatic lifting mechanism (4) is determined to be in a state where the tractor (1) is stopped after the end of the turning operation is determined. The tractor according to claim 1, wherein the automatic lowering mechanism (5) cannot be automatically lowered.

Cleaning and maintenance performed with the work machine (2) raised to the non-working position are usually performed with the tractor stopped, so that the work machine can be moved using the automatic work machine lift control device during turning. If the tractor (1) is stopped after the turning operation is finished in the case of automatic ascent, the automatic lowering mechanism (5) will not work, and cleaning and maintenance work with the work implement held in the raised position Can do.

First, in the invention described in claim 1, when the work implement (2) is normally raised by manual operation or the like, when removing mud and wound grass adhering to the cultivating sword or the cultivating shaft, or There are many cases of maintenance work such as parts replacement. Therefore, the operator moves the tractor (1) to the maintenance place while operating the handle, but when the work implement automatic lifting control device at the time of turning works and returns the handle, the automatic lowering mechanism (5) On the contrary, the work machine (2) is lowered. In such a case, the invention of claim 1 is directed to the work machine (2) when the operator has raised the non-working position to the height of the non-working position by an operation other than the automatic lifting mechanism (4), for example. Even after the end of the turning operation is determined, the configuration in which the automatic lowering by the automatic lowering mechanism (5) is regulated so that it cannot be automatically lowered has an excellent feature that can be safely cleaned and maintained.
In addition, since the operator can cancel the condition that the automatic lowering by the automatic lowering mechanism (5) is prohibited by the touch operation on the screen of the monitor (30), the operation becomes easy.

And invention of Claim 2 is, for example, when the tractor (1) reaches the end of the field while plowing work by the rotary tiller (2), mud and grass of the rotary tiller (2) is removed. You may want to clean or perform maintenance. In such a case, the invention of claim 2 uses the work implement automatic raising / lowering control device at the time of turning to raise the work implement, and when the set time elapses while traveling to the maintenance place while continuing the turning operation, Since the work machine (2) cannot be automatically lowered, the work machine (2) can be kept in the raised position and can be safely cleaned and maintained.

In the invention described in claim 3, when the work implement (2) is automatically raised using the work implement automatic raising / lowering control device during turning in the middle of work, when the turning operation is completed, the tractor (1 If the vehicle is stopped, the operation of the automatic lowering mechanism (5) is restricted, and the work implement (2) can be held in the raised position, so that cleaning and maintenance work can be safely performed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to an embodiment of a work implement automatic raising / lowering control device for turning equipped in an agricultural tractor shown in the drawings.
First, as shown in FIG. 2, the tractor 1 has an engine 7 mounted in a front bonnet 6, a clutch housing that houses a main clutch at the rear of the engine 7, and a transmission case 8 that houses a gear-type transmission. Are integrally connected. The tractor 1 is configured by providing rear axle cases 9 on the left and right sides of the rear portion of the mission case 8 and pivoting wheels 10 and 10 on the ends of the case 9 on both the left and right sides.

Further, a front axle case is provided below the engine 7 so as to be able to roll around a front and rear axis, and left and right front wheels 11 and 11 are provided to be steerable at both side ends.
The cockpit 12 is provided in a cabin 13 mounted on the vehicle body, and has a configuration in which a meter panel 14, a steering handle 15, and other operation levers are concentrated on the front side. The operator sits on the cockpit 12 and the left and right front wheels 11 and 11 are steered by the steering operation of the steering handle 15 so that the course can be changed and the vehicle can turn.

Also, in the vicinity of the levers, a work implement raising / lowering switch 16 (an up / down switch 16a / down switch 16b) and an automatic raising / lowering on / off switch 17 which will be described later (see FIG. 1) are arranged. It is the structure relevant to the working machine automatic raising / lowering control apparatus at the time of a certain turning.

As shown in FIG. 2, the tractor 1 is provided with a cylinder case 18 in which a hydraulic cylinder for raising and lowering the work implement is installed at the rear upper position of the transmission case 8. The lift arm 19 is rotated up and down by expanding and contracting the piston of the hydraulic cylinder in the cylinder case 18, and the rear rotary tiller (the working machine of the present application is connected to the lift arm 19 via a 3P link connected thereto. 2 corresponds to 2). One of the lift arms 19 is provided with a potentiometer type lift arm (angle) sensor 20 for detecting the height of the work implement, and the detection position of the potentiometer at the operation position for raising and lowering the work implement, and the lift arm 19 described above. The switching control valve for raising or lowering the work implement in the hydraulic circuit is switched by a control signal from a controller for raising and lowering control so that the rotation setting position matches.

Next, an embodiment will be described with respect to a work implement automatic lifting control device during turning and a safety function device provided in association therewith.
First, as shown in FIG. 1, the controller 25 has a front wheel break angle sensor 26, a control lever 27, a lift arm sensor 20, and a work implement lift switch 16 (the lift switch 16a and the drop switch 16b already described) on the input side. ), An automatic up / down switch 17 and a vehicle speed sensor 28 are connected to each other, and detection information and operation information are input. Then, the controller 25 is provided with a lift arm raising solenoid 29a (electromagnetic valve) and a lift arm lowering solenoid 29b connected to the output side, and outputs a control signal to supply the hydraulic oil for raising and lowering the work machine. Are switched. The automatic raising mechanism 4 described in claims 1, 2 and 3 refers to the lift arm raising solenoid 29a and the raising device related thereto, and the automatic lowering mechanism 5 refers to the lift arm lowering solenoid 29b and this. Refers to the lowering device associated with.

When the controller 25 continues the operation by the rotary tiller 2 while steering the steering handle 15 as the tractor 1 travels, the front wheel break angle sensor 26 always monitors the cut angles of the front wheels 3 and 3. Although the measured detection value is input, the control function is provided to determine that the tractor 1 has entered a turn when the turning angle becomes approximately 40 degrees or more. Then, the controller 25 outputs a turning start control signal to the lift arm raising solenoid 29a to operate the automatic raising mechanism 4 and raise the rotary tiller 2 to the non-working position while rotating the lift arm 19 upward. It is configured.

The controller 25 determines that the turning operation is finished when the turning angle of the front wheels 3 and 3 is less than about 40 degrees in the process of returning the steering handle 15 after the turning of the tractor 1 is completed, Under a slight time lag, a control signal is output to the lift arm lowering solenoid 29b, the automatic lowering mechanism 5 is actuated to rotate the lift arm 19 downward, and the rotary tiller 2 is automatically moved to a work position close to the field scene. It is configured to descend.

In this way, the controller 25 always causes the front wheel turning angle sensor 26 to monitor and measure the turning angle of the front wheels 3 and 3 that are turned according to the steering operation of the steering handle 15. Based on 40 degrees as a reference, a device for determining whether or not the vehicle is turning and automatically lifting and lowering the work machine 2 is configured.

As shown in FIG. 1, the controller 25 is connected to the monitor 30 and is configured so that the state of the automatic raising / lowering of the rotary tiller 2 can be confirmed on the TV screen, and is automatically lowered by the automatic lowering mechanism 5 described below. This condition is set so that the operator can cancel the condition by a touch operation on the screen of the monitor 30.

Next, each embodiment in which the automatic lowering by the automatic lowering mechanism 5 is prohibited in the automatic working machine lifting control device at the time of turning will be described.
First, in the first embodiment, an operation other than the automatic ascending mechanism 4 by the work implement automatic ascent / descent control device at the time of turning is performed, for example, an operator manually operates the ascent switch 16a in the work implement elevating switch 16. Thus, when the work implement 2 is raised and preparations for maintenance work are performed, the automatic lowering mechanism 5 cannot be automatically lowered even if it is determined that the turning operation is finished.

If it demonstrates with the flowchart shown in FIG. 3, the automatic raising / lowering on / off switch 17 connected to the controller 25 will be turned ON, the working machine automatic raising / lowering control apparatus at the time of turning will be started, and work will be started. When the tractor 1 reaches the turning position in the field and turns the steering handle 15, the controller 25 measures and inputs the turning angle of the front wheels 3 and 3 by the turning angle sensor 26. When the turning angle exceeds 40 degrees, the controller 25 determines that the vehicle is turning and outputs a control signal for switching the lift arm raising solenoid 29a to the ascending side. In the first embodiment, since the rotary tiller 2 has already been lifted by manual operation, the lift control is not performed, and as shown in the flowchart of FIG. 3, auto-down is prohibited and the turning operation is completed. However, the rotary tiller 2 is not automatically lowered and safety is ensured.

In normal tillage work, when the rotary tiller 2 is lifted manually during operation, when removing mud and entangled grass attached to the tillage blade or tiller shaft, or replacing parts such as the tillage blade In many cases, such as maintenance work. Therefore, in the first embodiment, after the operator lifts the rotary tiller 2 manually, the operator automatically operates the steering handle 15 and moves the tractor 1 to the maintenance place. When the apparatus is operated and the handle is returned, the automatic lowering mechanism 5 ensures safety so that the working machine 2 does not descend unexpectedly. As described above, in the first embodiment, the rotary tiller 2 is not automatically raised in relation to turning, for example, when it is raised manually to the height of the non-working position by the raising switch 16a. In this case, even after the end of the turning operation is determined, automatic lowering by the automatic lowering mechanism 5 cannot be performed, so that cleaning and maintenance work can be performed safely.

Next, the second embodiment is configured such that the automatic lowering mechanism 5 cannot be automatically lowered when a set time elapses after the rotary tiller 2 raised by the automatic raising mechanism 4 rises. In the second embodiment, as shown in the flowchart of FIG. 3, auto-down is prohibited as the set time elapses, and safety is ensured.

For example, it may be necessary to perform cleaning and maintenance to remove mud and grass of the tillage device 2 during the tillage work by the rotary tiller 2. In such a case, when the set time elapses during the second embodiment, the work implement is lifted using the automatic work equipment lift control device during turning and travels to the maintenance place while continuing the turning operation. Since the working machine 2 cannot be lowered automatically, the rotary tiller 2 can be kept in the raised position, and cleaning and maintenance work can be performed safely.

Next, in the third embodiment, the rotary tiller 2 raised by the automatic raising mechanism 4 is configured such that the automatic lowering mechanism 5 does not work if the tractor 1 is stopped after the end of the turning operation is determined. It has become. In this case, as already described, the rotation of the rear wheel axle is input from the vehicle speed sensor 28, and the controller 25 determines whether the vehicle is running or stopped based on this input information.

In the third embodiment, as shown in the flowchart of FIG. 3, when the tractor 1 is stopped, the rotary tiller 2 is prohibited from being automatically down, and the safety of the subsequent work is ensured.

Accordingly, in the third embodiment, when the rotary tiller 2 is automatically raised using the automatic working machine lifting control device during turning in the middle of the tilling work, the tractor 1 is stopped when the turning operation is finished. Then, the operation of the automatic lowering mechanism 5 is restricted, and the tilling device 2 can be kept in the raised non-working position, so that it can enter the lower side of the work machine 2 and perform cleaning and maintenance work safely. It became possible.

Normally, cleaning and maintenance work of the rotary tiller 2 is performed after moving to a safe place, and after stopping the tractor 1 and fixing the vehicle body with a vehicle stop or the like, the third embodiment is extremely effective. It can be used for.

Next, as shown in FIG. 2, the tractor 1 is provided with a PTO-off switch 31 at the rear position outside the cabin 13 in the embodiment, so that an auxiliary worker can turn off the PTO from the rear outside the vehicle. It is said. In this case, as shown in FIG. 4, the controller 32 of the embodiment has a configuration in which a PTO switch (inside the cabin) 33 and an engine rotation sensor 34 are connected to the input side in addition to the PTO off switch 31 outside the vehicle. It is said. The controller 32 is configured to connect the PTO solenoid 35 to the output side and electromagnetically operate the PTO clutch on / off based on the output control signal. Then, the controller 32 outputs a control signal based on the operation of the PTO off switch 31 and disengages the PTO clutch by the PTO solenoid 35 to stop the work machine. Thereafter, the engine speed is set to the specified rotational speed (500 rpm in the case of the embodiment). ) Until it falls below, it is configured to keep it off.

In the above embodiment, as shown in the flowchart of FIG. 5, when an auxiliary worker outside the vehicle turns off the transmission of the PTO with the PTO switch 31 and, for example, replaces the cultivating sword of the rotary cultivator 2. Even if the operator in the cabin 13 turns on the PTO switch 33 in the vehicle without noticing the behavior of the auxiliary worker, the output stop of the PTO solenoid 35 is maintained if the engine speed does not drop below 500 rpm. The transmission is interrupted and the maintenance work can be continued safely.

Next, an embodiment of the operating device for the continuously variable transmission will be described with reference to FIGS. 6 and 7.
Conventionally known continuously variable transmissions such as tractors, as shown in the drawings, are configured to perform forward / reverse switching and speed increase / decrease speed adjustment by a continuously variable transmission lever 40. As can be seen from FIG. 7, the forward shift position F can be switched to the forward position F and the backward position R can be switched to the forward position F by moving the shift guide groove 41 to the front side around the neutral position N. Further, the neutral position N is set to 0, and the gear can be shifted to the speed increasing side as the distance from the neutral position N increases. In this known configuration, the forward / backward movement is switched by a single continuously variable transmission lever 40, and the operation stroke becomes longer to adjust the acceleration / deceleration, which places an operational burden on the operator and is difficult to use. There are challenges.

Each embodiment described below provides a device that solves the above-described problems, simplifies a continuously variable transmission operation, and can be operated easily and efficiently.
First, as shown in FIGS. 6 and 7, the continuously variable transmission lever 40 is provided in a transmission guide groove 41 disposed in the front-rear direction on the left side of the cockpit 42 and is operated in the front-rear direction. The shift guide groove 41 is configured such that the front side is the forward position F and the rear side is the reverse position R with the neutral position N as the center, and the higher the distance from the neutral position N, as described above.

In the first embodiment, a forward / reverse switching lever 43 that performs only forward / reverse switching is provided near the left side of the steering handle 15 so that the forward / backward switching operation can be easily performed at a position close to the handle 15. It is said.

In the second embodiment, as shown in FIG. 6, in the forward / reverse switching lever 43, the forward / backward switching position can be switched back and forth between the forward side and the backward side. In FIG. 2, the acceleration / deceleration operation areas are provided above and below, respectively, so that the speed change operation can be performed.

As described above, the speed change operation can be easily switched between forward and backward movements compared with the conventional continuously variable transmission lever 40 in a long range of operation strokes. There are advantages you can do.

Next, the third embodiment is provided with a vehicle speed change switch 45 composed of a speed increasing switch 45a and a speed reducing switch 45b so that the speed change operation of the vehicle speed can be easily performed by the switch operation. The speed can be changed to the vehicle speed. Shifting can be done easily.

The vehicle speed change switch 45 is configured to change the maximum vehicle speed while being operated, and has a feature that a large speed change can be performed at once.
The speed increasing switch 45a and the speed reducing switch 45b are configured so that the speed increasing rate and the speed decreasing rate increase sequentially as the operation time (the time during which the switch is turned on in a continuous state) becomes longer, depending on the operator's intention to shift. It is supposed to be. The speed increase rate and the speed reduction rate corresponding to the continuous operation time of both switches 45a and 45b are set so as to prevent an unexpected overshoot by setting a maximum increase width in order to avoid excessive shifting.

In the fourth embodiment, the vehicle speed in steps is changed between a zone where the vehicle speed is fast and a zone where the vehicle speed is slow. In the embodiment, when the maximum vehicle speed is about 1 km / h, it is about 0.05 km / h, and when it is 10 km / h, it is about 0.5 km / h. As a result, the fourth embodiment provides the necessary vehicle speed resolution in accordance with the work, and fine adjustment during the work is not performed by operating the lever 43 (see the second embodiment). Since it can be adjusted in stages, it has the feature that it is easy to select a vehicle speed suitable for work.

In addition, there is an advantage that a proper resolution can be distributed to some extent depending on the maximum vehicle speed as a configuration in which the increment at the time of the switch operation in the above embodiment is changed at a specified ratio of about 1/20 of the set maximum vehicle speed.

The speed change control device of the continuously variable transmission described above has a specified acceleration in order to prevent sudden acceleration or sudden deceleration when the vehicle speed shift switch 45 is operated continuously, particularly when operated continuously. It is configured to ensure the safety of driving by giving a function to control so as not to exceed. In the embodiment, in order to prevent the adverse effects caused by the acceleration, the acceleration accompanying the traveling at the time of the shift can be finely adjusted, and the stable traveling can be performed at the speed more appropriately shifted.

Next, an example of the check chain 51, 51 connected to the left and right lower links 50, 50 will be described with reference to FIGS.
First, the check chains 51 and 51 are connected to the pistons 52p and 52p of the hydraulic cylinders 52 and 52 by connecting the tip portions to the left and right lower links 50 and 50 of the 3P link. The pistons 52p and 52p that expand and contract in accordance with the operation can swing the distal end side (work machine side) to the left and right with the lower links 50 and 50 serving as fulcrums. In the embodiment, as shown in FIG. 8, the left and right hydraulic cylinders 52, 52 are connected to switching valves 53, 53, respectively, and an operation switch 55 on an operation plate 54 (see FIG. 9) installed in the cabin. , 55 can be switched separately on the left and right.

As shown in FIG. 9, the operation plate 54 has a configuration in which it is separately arranged on the plate separately into an extension switch 55 a and a contraction switch 55 b. The alarm lamp is composed of a left 56L and a right 56R. When an excessive pressure is applied to the hydraulic cylinders 52, 52, the expansion / contraction operation of the cylinder is automatically stopped and an automatic alarm is issued at the same time.

As shown in FIG. 12, the operation plate 54 is configured by adding an alarm buzzer 57 instead of the above-described configuration (see FIG. 9) and further adding left and right offset switches 58L and 58R. And as shown in FIG. 13, the potentiometer 60 is configured to detect the amount of expansion of the pistons 52p, 52p and to be input to a controller (not shown).

The left and right lower links 50, 50 configured as described above are provided with check chains 51, 51 connected to the pistons 52 p, 52 p of the hydraulic cylinders 52, 52 on the outside, and the two embodiments of FIGS. 9 and 12. The operation switch on the operation plate 54 can be operated.

For example, as shown in FIGS. 10 and 11, the lower links 50 and 50 are offset to the right side (FIG. 10⇒FIG. 10) when the offset switch 58R (or 58L) on the operation plate 54 (see FIG. 12) is turned ON. 11) can. As described above, the lower links 50 and 50 of the embodiment switch the rotary tiller as described above while keeping the tractor straight when there is an obstacle (electric pole, etc.) in the field during the tillage work. It is now possible to cultivate in a state where it cannot be plowed in the field by plowing it horizontally by operation.

Block diagram showing the control mechanism Overall side view of tractor Flow chart of control action Block diagram of control mechanism of embodiment The flowchart figure of the control action of an Example Plan view of the tractor of the embodiment Slope view of continuously variable transmission lever Schematic of the operating mechanism of lower link and chain Top view of the operation panel Plan view of the normal position of the lower link Plan view of lower link offset position Plan view of another embodiment of the check chain operation plate The top view of the hydraulic cylinder connected to the check chain.

DESCRIPTION OF SYMBOLS 1 Tractor 2 Working machine 3, 3 Front wheel 4 Automatic raising mechanism 5 Automatic lowering mechanism
25 controllers
30 monitors

Claims (3)

The tractor (1) is provided with a work machine (2) freely moving up and down, and an automatic raising mechanism (4) is provided for raising the work machine (2) when the cutting angle of the front wheel (3) exceeds a set value. When the turning angle of the front wheel (3) becomes less than a set value, the ascending movement is performed manually by the tractor during turning provided with the automatic lowering mechanism (5) for lowering the work implement (2). The broken work machine (2) is configured not to be automatically lowered by the automatic lowering mechanism (5) even after the end of the turning operation is determined .
A controller 25 is provided connected to a monitor (30), and the state of automatic lifting / lowering of the work machine (2) can be confirmed on a television screen,
A tractor characterized in that an operator can cancel a condition in which automatic lowering by the automatic lowering mechanism (5) is prohibited by a touch operation on the screen of the monitor (30) . The tractor according to claim 1, wherein the work implement (2) raised by the automatic raising mechanism (4) cannot be automatically lowered by the automatic lowering mechanism (5) when a set time elapses after being raised. The work implement (2) raised by the automatic raising mechanism (4) cannot be automatically lowered by the automatic lowering mechanism (5) if the tractor (1) is stopped after the end of the turning operation is determined. The tractor according to claim 1, which is configured.

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