Work vehicles

Abstract

To solve the problem that conventionally, there is a possibility that a tractor unintentionally becomes one brake state, and unexpectedly moves according to a situation such as stopping in a slope.SOLUTION: A work vehicle includes: right and left brake devices for braking each of right and left rear wheels 5; right and left brake pedals 12L and 12R for operating each of the right and left brake devices; a pedal connection release operation part 30 capable of releasing connection of the right and left brake pedals 12L and 12R by step-in operation; a release lock lever 34 for inhibiting connection release operation of the pedal connection release operation part 30, and dissolving the inhibition; a parking brake device 40 for fixing and maintaining a state in which one pedal of the right and left brake pedals 12L and 12R is stepped in; and restraining devices 34a and 40a for preventing simultaneous operation of operation for actuating the parking brake device 40 and operation for dissolving the inhibition of the connection release operation of the pedal connection release operation part 30 by the release lock lever 34.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a work vehicle such as a tractor, and particularly to the disconnection of left and right brakes that brake the left and right wheels, and the application and switching of a parking brake. [Background technology]

[0002] A known work vehicle is equipped with left and right braking devices that brake the left and right rear wheels, respectively, left and right brake pedals that operate the left and right braking devices, respectively, and a disconnection pedal that operates a connecting piece that connects the left and right brake pedals to switch between connection and disconnection (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-24293 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0004] According to the configuration of Patent Document 1, when the vehicle is stopped and the parking brake is applied, the coupling is released by stepping on the coupling release pedal that switches between coupling and uncoupling, and only one of the brakes can be released.

[0005] This could result in an unintentional braking state, which could cause the vehicle to suddenly start moving in certain situations, such as when stopped on a slope.

[0006] An object of the present invention is to provide a work vehicle that allows safe operation of the parking brake and single brake. [Means for solving the problem]

[0007] The above-mentioned problems of the present invention are solved by the following means.

[0008] The first aspect of the present invention is Left and right braking devices that brake the left and right rear wheels, respectively; left and right brake pedals for operating the left and right braking devices, respectively; a pedal disconnection operation unit that can disconnect the left and right brake pedals by stepping on it; a release lock lever that can prohibit the pedal release operation unit from releasing the coupling, and can also cancel this prohibition; a parking brake device that keeps one of the left and right brake pedals in a depressed state; a restraining device that prevents an operation to activate the parking brake device and an operation to release the prohibition of the pedal disconnection operation unit by the release lock lever from being performed simultaneously, The restraining device is a first check plate that is interlocked with the operation of the release lock lever; and a second check plate that is interlocked with the operation of the parking brake device, When the release lock lever is operated to release the prohibition of the coupling release operation of the pedal coupling release operation unit, the first check plate abuts against the second check plate to restrict the operation of the parking brake device, This is a work vehicle in which, when an operation to activate the parking brake device is performed, the second restraint plate abuts against the first restraint plate, thereby restricting the operation to release the prohibition on the disconnection operation of the pedal disconnection operating unit by the release lock lever. The second aspect of the present invention is The first check plate has a first recess and a first protrusion, and rotates in conjunction with the operation of the release lock lever. the second check plate has a second recess and a second protrusion, and rotates in conjunction with the operation of the parking brake device; When the release lock lever prohibits the release operation of the pedal release operation unit and the parking brake device is not depressed, the first protrusion of the first check plate does not enter the second recess of the second check plate, and the second protrusion of the second check plate does not enter the first recess of the first check plate, When the prohibition of the coupling release operation of the pedal coupling release operation unit is lifted by the release lock lever, the first convex portion of the first check plate enters the second concave portion of the second check plate, thereby preventing the second check plate from moving and restricting the operation of the parking brake device, This is the first work vehicle of the present invention, in which when the parking brake device is depressed, the second convex portion of the second restraining plate enters the first concave portion of the first restraining plate, thereby preventing the first restraining plate from moving and restricting the release lock lever from lifting the prohibition on the pedal uncoupling operation unit from being uncoupled. The third aspect of the present invention is The release lock lever is composed of an operating part that protrudes rearward and is movable up and down, and a rod part whose tip is bent and extended downward, and the release operation of the pedal connection release operating part can be prohibited or lifted by the vertical movement of the lower end of the rod part in response to the vertical movement of the operating part, The first check plate is rotatably connected to the vehicle body frame, and the tip of the operating part is inserted into a hole formed in the rear end part of the first check plate, and the first check plate rotates in response to the up and down movement of the operating part of the release lock lever. The parking brake pedal of the parking brake device is fixed to a cylindrical member rotatably mounted on a shaft fixed to the vehicle body frame, The second check plate is attached to the cylindrical member and rotates when the parking brake pedal is depressed, In a second aspect of the present invention, there is provided a work vehicle, wherein the first check plate and the second check plate are disposed opposite each other. The fourth aspect of the present invention is the pedal disconnection operating unit has a pedal unit, a base end portion connected to the pedal unit, and a rotation center located at a central position of the base end portion and serving as a rotation center of the pedal disconnection operating unit, An arc-shaped hole having the rotation center as its center is drilled in the base end portion, The lower end of the rod portion is engaged with the hole, The hole restricts the rotation range of the pedal disconnection operating part, In a third work vehicle of the present invention, the position at which the hole can exist changes depending on the vertical position of the lower end, and the rotation range of the pedal release operating part changes depending on this change. First invention related to the present invention teeth, Left and right braking devices that brake the left and right rear wheels, respectively; left and right brake pedals for operating the left and right braking devices, respectively; a pedal disconnection operation unit that can disconnect the left and right brake pedals by stepping on it; a release lock lever that can prohibit the pedal release operation unit from releasing the coupling, and can also cancel this prohibition; a parking brake device that keeps one of the left and right brake pedals in a depressed state; This work vehicle is characterized by being equipped with a restraining device that prevents the operation of activating the parking brake device and the operation of releasing the prohibition on the pedal uncoupling operation unit by the release lock lever from being performed simultaneously.

[0009] Second invention related to the present invention teeth, The restraining device is a first check plate that is interlocked with the operation of the release lock lever; and a second check plate that is interlocked with the operation of the parking brake device, When the release lock lever is operated to release the prohibition of the coupling release operation of the pedal coupling release operation unit, the first check plate abuts against the second check plate to restrict the operation of the parking brake device, When an operation to activate the parking brake device is performed, the second check plate abuts against the first check plate, restricting an operation to release the prohibition of the disconnection operation of the pedal disconnection operation unit by the release lock lever. First invention related to the present invention It is a work vehicle.

[0010] Third invention related to the present invention teeth, The first check plate has a first recess and a first protrusion, and rotates in conjunction with the operation of the release lock lever. the second check plate has a second recess and a second protrusion, and rotates in conjunction with the operation of the parking brake device; When the release lock lever prohibits the release operation of the pedal release operation unit and the parking brake device is not depressed, the first protrusion of the first check plate does not enter the second recess of the second check plate, and the second protrusion of the second check plate does not enter the first recess of the first check plate, When the prohibition of the coupling release operation of the pedal coupling release operation unit is lifted by the release lock lever, the first convex portion of the first check plate enters the second concave portion of the second check plate, thereby preventing the second check plate from moving and restricting the operation of the parking brake device, When the parking brake device is depressed, the second convex portion of the second check plate enters the first concave portion of the first check plate, thereby preventing the first check plate from moving and restricting the release lock lever from lifting the prohibition on the pedal disconnection operation unit. Second invention related to the present invention It is a work vehicle.

[0011] The fourth invention related to the present invention teeth, The release lock lever is composed of an operating part that protrudes rearward and is movable up and down, and a rod part whose tip is bent and extended downward, and the release operation of the pedal connection release operating part can be prohibited or lifted by the vertical movement of the lower end of the rod part in response to the vertical movement of the operating part, The first check plate is rotatably connected to the vehicle body frame, and the tip of the operating part is inserted into a hole formed in the rear end part of the first check plate, and the first check plate rotates in response to the up and down movement of the operating part of the release lock lever. The parking brake pedal of the parking brake device is fixed to a cylindrical member rotatably mounted on a shaft fixed to the vehicle body frame, The second check plate is attached to the cylindrical member and rotates when the parking brake pedal is depressed, The first check plate and the second check plate are disposed opposite each other. Third invention related to the present invention It is a work vehicle.

[0012] Fifth Invention Related to the Present Invention teeth, the pedal disconnection operating unit has a pedal portion, a base end portion connected to the pedal portion, and a rotation center located at a central position of the base end portion and serving as a rotation center of the pedal disconnection operating unit, An arc-shaped hole having the rotation center as its center is drilled in the base end portion, The lower end of the rod portion is engaged with the hole, The hole restricts the rotation range of the pedal disconnection operating part, The position where the hole can be present changes depending on the vertical position of the lower end, and depending on this change, The rotation range of the pedal connection release operation unit is changed. The fourth invention related to the present invention It is a work vehicle. [Effects of the Invention]

[0013] According to the present invention, a safe work vehicle can be provided without the risk of one-sided braking even when parked on a slope or the like. In addition, by simply adjusting the two up and down positions of the release lock lever, the pedal release operation part can be set to one of three different states: stored state (locked state for release), horizontal state in the basic position (unlocked state for release), and tilted state (released state). [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a schematic left side view of a tractor according to an embodiment of the present invention; [Figure 2] A perspective view of the front of the driver's seat of the tractor [Figure 3] FIG. 10 is a side view showing the tractor in a state where the release lock lever is in a downward position and the parking brake pedal is not depressed. [Figure 4] FIG. 10 is a side view showing the tractor in a state where the release lock lever is in a downward position and the parking brake pedal is depressed. [Figure 5] FIG. 10 is a side view showing the tractor in a state where the release lock lever is in an upward position and the coupling can be released, and the parking brake pedal is not depressed. [Figure 6]FIG. 1 is a side view showing the state in which the pedal disconnection operating unit is depressed to disconnect the left and right brake pedals in the tractor when the release lock lever is in the lower position and in the release lock state and the parking brake pedal is not depressed. DETAILED DESCRIPTION OF THE INVENTION

[0015] An embodiment of the present invention will be described with reference to the drawings.

[0016] The tractor 1 as a work vehicle is an agricultural tractor that drives itself and performs work in fields, etc. Note that front and rear are defined based on the direction of travel, and left and right are defined as looking forward from the operator in the driver's seat.

[0017] As shown in Figure 1, an engine E is mounted inside a hood 2 at the front of the vehicle body. Rotational power from the engine E is transmitted to a traveling transmission device inside a transmission case 3, where it is reduced in speed and transmitted to the wheels, i.e., the front wheels 4 and rear wheels 5 of the tractor 1.

[0018] A cockpit 7 is provided in a cabin 6 at the rear of the aircraft. A steering handle 8 for steering the front wheels 4 is provided in front of the cockpit 7. A meter panel 9 is provided in front of the steering handle 8.

[0019] On the other hand, a rotary working machine or the like is connected to the rear of the machine body. Such a working machine is driven by a PTO shaft 13 that protrudes rearward from the transmission case 3.

[0020] In addition, within the cabin 6, around the cockpit 7, there are provided a steering wheel 8, a meter panel 9, various operation pedals such as an accelerator pedal 10, a clutch pedal 11, and a brake pedal 12 (left and right brake pedals 12L, 12R), as well as various operation levers such as a forward / reverse lever 14, a main shift lever 15, and an auxiliary shift lever 16.

[0021] The transmission case 3 houses a forward / reverse switching mechanism, a main transmission mechanism, an auxiliary transmission mechanism (not shown), a transmission mechanism to the rear wheels 5 and the front wheels 4, and left and right brake mechanisms (braking devices, not shown) that brake the left and right axles of the left and right rear wheels 5, respectively.

[0022] <About connecting the left and right pedals> As shown in FIG. 2, the left and right brake pedals 12L, 12R are provided at the lower ends of arms 23, 23 that are fixed to a left base tube 22 and a right base tube 22′ and extend downward, and are rotatably supported on a base shaft extending in the left-right direction.

[0023] The arms 23, 23 are biased by biasing members 24, 24 such as springs in the direction opposite to the direction in which the operator presses the left base cylinder 22 and the right base cylinder 22'. A pedal connecting portion 25 that connects the left and right brake pedals 12L, 12R is provided at a midpoint of the arms 23, 23.

[0024] The pedal connecting portion 25 includes a connecting piece 26 and a receiving portion 27. The connecting piece 26 is attached to an arm 23 on which one of the left and right brake pedals (for example, the left brake pedal 12L) is mounted so as to be rotatable in a direction substantially perpendicular to the extension direction of the arm 23. On the other hand, the receiving portion 27 is provided on the arm 23 on which the other of the left and right brake pedals (for example, the right brake pedal 12R) is mounted.

[0025] The pedal connection portion 25 configured in this manner connects the left and right arms 23, 23 by rotating the connection piece 26 around the pivot axis 26a and fitting the tip of the connection piece 26 into the hook-shaped receiving portion 27.

[0026] In this way, by connecting the left and right arms 23, 23 by the pedal connecting portion 25, the left and right brake pedals 12L, 12R become substantially integrated, and when the operator depresses them, they operate together.

[0027] The operation of connecting the left and right brake pedals 12L, 12R and simultaneously depressing both pedals is generally used when the machine is traveling normally on a road, or when traveling straight ahead in a field, etc.

[0028] On the other hand, the operation of decoupling the left and right brake pedals 12L, 12R and depressing them individually is used when turning the machine in a field or the like. <About unbundling> The connecting piece 26 of the pedal connecting portion 25 is connected to a wire 28, and when the operator depresses the pedal portion 30a of the pedal connection release operation unit 30 (see FIG. 2), it is pulled up by the wire 28, and the connection between the left and right brake pedals 12L, 12R is released. When the operator removes his / her foot from the pedal connection release operation unit 30, the pulling up of the connecting piece 26 by the wire 28 is released, and the connecting piece 26 rotates and fits into the receiving portion 27, connecting the left and right brake pedals 12L, 12R.

[0029] The pedal disconnection operating unit 30 described above is provided at the bottom of the handlebar post (not shown) and protrudes toward the pilot's seat 7. As shown in FIGS. 2 and 3, the pedal disconnection operating unit 30 has a pedal portion 30a at its tip. A base end portion 30b of the pedal disconnection operating unit 30 is provided rotatably about a rotation center 30e and is rotated when the operator steps on it. The pedal disconnection operating unit 30 is biased to rotate counterclockwise by a spring (not shown) or the like, and can be in one of three states: a stowed state (see FIGS. 2, 3, and 4) in which it is rotated all the way up to prevent accidental depression; a horizontal state (see FIG. 5) which is a basic position in which it is maintained approximately horizontal to make it easier to step on; and an inclined state (see FIG. 6) in which it is depressed and rotated downward to release the pedal connection.

[0030] An arc-shaped hole 30d is bored in the plate-like base end 30b, with its center at the pivot point 30e. A push bar 30c extends horizontally from the right side of its lower end. A wire plate 31 is disposed below the push bar 30c. The wire plate 31 is pivotally connected to a shaft 31a fixed to the vehicle body. A release pin 31b extends horizontally from the left side of the front end of the wire plate 30c. The lower end of the wire 28 is connected to the release pin 31b, as shown in FIG. 6.

[0031] Therefore, when releasing the connection, the pedal portion 30a of the pedal release operating unit 30 is stepped on, causing the base end portion 30b to rotate and the push bar 30c to rotate clockwise (on the paper surface of Figure 3), resulting in the push bar 30c abutting against the top of the wire plate 31 and rotating the wire plate 31 counterclockwise (the push bar 30c and the top of the wire plate 31 are positioned in such a positional relationship).

[0032] As a result, the pedal disconnection operating unit 30 is in the inclined state as shown in Figure 6, and the release pin 31b also rotates counterclockwise, the wire 28 is pulled downward, and the connecting piece 26 of the pedal connecting unit 25, which is connected to the wire 28, is pulled upward, thereby releasing the connection between the left and right brake pedals 12L, 12R.

[0033] <About detecting connection status> 2 and 3, a detector (pedal coupling operation detection switch) 37 that detects the coupling operation by the pedal uncoupling operation unit 30 is provided near the pedal uncoupling operation unit 30. Specifically, the pedal coupling operation detection switch 37 is provided above and in front of the base end 30b of the pedal uncoupling operation unit 30. When the pedal uncoupling operation unit 30 rotates and the base end 30b rotates, the first detection protrusion 30b1 rotates accordingly, pressing the sensing unit 37a. This detects the operation status of the pedal uncoupling operation unit 30. When the switch is ON, it indicates that the left and right brake pedals 12L, 12R are coupled, and when the switch is OFF, it indicates that the pedals are uncoupled. The positional relationship between the first detection protrusion 30b1 and the sensing unit 37a is designed to operate in this manner.

[0034] 5, the pedal uncoupling operation unit 30 is in the basic position (horizontal state), and the sensing portion 37a of the pedal coupling operation detection switch 37 is pressed to detect a state in which the left and right brake pedals 12L, 12R are coupled by the pedal coupling portion 25. When the pedal uncoupling operation unit 30 is in a tilted position as shown in FIG. 6, the switch detects a state in which the left and right brake pedals 12L, 12R are uncoupled by the pedal coupling portion 25.

[0035] <About the disconnection lock> 3, a rod-shaped operating part 34d is disposed above the pedal connection release operating part 30 and protrudes toward the operator, with its tip bent downward to form a vertically long rod part 34e that extends downward, and whose lower end 34f is engaged in the arc-shaped hole 30d formed in the base end part 30b. The operating part 34d and rod part 34e are members that constitute the release lock lever 34.

[0036] On the other hand, a V-shaped first check plate 34a is fixed to a cylinder 34b that is rotatably mounted on a shaft fixed to the body frame, and an operating portion 34d of this release lock lever 34 is inserted into a hole 34a3 at the rear end of the cylinder 34b. The role of this first check plate 34a will be described later.

[0037] Furthermore, the operating part 34d of the release lock lever 34 is inserted into a guide groove 34g of a guide plate 34c fixed to the body frame. The guide groove 34g is U-shaped and can guide the operating part 34d in the vertical direction and in the horizontal direction at the top and bottom ends.

[0038] By moving the operating portion 34d of the release lock lever 34 downward along the guide groove 34g and then moving it to the right at the lower end of the guide groove 34g and stabilizing it, the rod portion 34e and the lower end 34f move downward, creating room for rotation in the arc-shaped hole 30d to which the lower end 34f is engaged. This allows the pedal release operating portion 30, which is biased counterclockwise, to rotate counterclockwise and rotate to its uppermost position, thereby rotating to the storage position, which is difficult to press with the foot (see FIG. 3). At the same time, the lower end 34f of the rod portion 34e restricts (prohibits) the release movement of the pedal release operating portion 30 via the hole 30d. In other words, in the storage position, even if the pedal portion 30a is forcibly pressed down with the foot, the base end 30b of the pedal release operating portion 30 cannot rotate clockwise much (restricted by the hole 30d). Therefore, if the lower end 34f is positioned downward, it will not be able to press the wire plate 31. As a result, the uncoupling movement is prevented (prohibited) and uncoupling is locked (state shown in Figure 3).

[0039] In response to this, by moving the operating part 34d of the release lock lever 34 upward along the guide groove 34g and stabilizing it by moving it to the right at the upper end of the guide groove 34g (releasing the connection release lock), the rod part 34e and the lower end 34f are pulled upward, the lower end 34f pulls up the upper end of the hole 30d, and the pedal connection release operating part 30 rotates clockwise to assume a basic position (approximately horizontal position) that is easy to step on with the foot (the horizontal state in Figure 5, in which the connection release lock is released).

[0040] Furthermore, in this state, when the pedal disconnection operating unit 30 is stepped on with the foot, the pedal disconnection operating unit 30 rotates clockwise within the range of the hole 30d, and the push bar 30c abuts against the wire plate 31, rotating it and releasing the connection (state shown in Figure 6).

[0041] In this way, the hole 30d restricts the rotation range of the pedal disconnection operating part 30, and the possible position of the hole 30d changes depending on the vertical position of the lower end 34f, and the rotation range of the pedal disconnection operating part 30 changes depending on this change.

[0042] As a result, by simply adjusting the two upper and lower positions of the release lock lever 34, the pedal release operation unit 30 can be set to one of three different states: a stored state (locked state for release), a horizontal state in the basic position (unlocked state for release), and an inclined state (released state).

[0043] <Detecting unlock> A sensing portion 38a of a lock operation detection switch 38, which detects whether the locked state of the coupling release has been released, is located further above the pedal coupling operation detection switch 37. The lock operation detection switch 38 is provided substantially directly above the base end 30b of the pedal coupling release operating unit 30, and when the base end 30b rotates, the second detection protrusion 30b2 rotates accordingly, pressing the sensing portion 38a. As a result, it can be detected that the coupling release lock has been released when the switch is on, and that the coupling release lock has been released when the switch is off.

[0044] In the example shown in FIG. 3, the pedal release operation unit 30 is in the stored position, the rod portion 34e of the release lock lever 34 is in a downward position, the base end 30b is restricted from rotating clockwise, and the second detection protrusion 30b2 is not in contact with the sensing portion 38a, resulting in an OFF state. In the examples shown in FIGS. 5 and 6, the rod portion 34e of the release lock lever 34 is in an upward position, disengaging the lock. Therefore, the pedal release operation unit 30 is in a horizontal or tilted position, the base end 30b is free to rotate clockwise, and the second detection protrusion 30b2 is in contact with the sensing portion 38a, resulting in an ON state. As a result, the lock operation detection switch 38 detects that the lock has been released. The positional relationship between the second detection protrusion 30b2 and the sensing portion 38a is designed to achieve this operation.

[0045] <About the parking brake> 2 and 3, reference numeral 40 denotes a parking brake pedal, which is disposed on the operator side and is an example of the parking brake device of the present invention. This parking brake pedal 40 is fixed to a tubular member 40e rotatably mounted on a shaft 40b fixed to the vehicle body frame, and a second check plate 40a is attached to the substantially opposite side of the tubular member 40e. The role of this second check plate 40a will be described later. Furthermore, a plate 40d protruding forward is fixed to the tubular member 40e.

[0046] On the other hand, a parking plate 40c having a jagged stepped portion at the bottom is fixed to the left base cylinder 22 near the plate 40d so that it can rotate together with the left base cylinder 22. When the left brake pedal 12L is depressed, the stepped portion of the parking plate 40c moves forward as shown by the dotted line in Figure 3.

[0047] Now, as shown in Figure 4, when the left brake pedal 12L is depressed to apply the left brake, the left base cylinder 22 rotates clockwise (on the paper surface of Figure 4), so the parking plate 40c also rotates and its stepped portion moves forward.

[0048] In this state, when the parking brake pedal 40 is depressed, the plate 40d rotates clockwise and begins to rise, and the tip of the plate 40d comes into contact with the lower part of the stepped portion of the parking plate 40c.

[0049] This prevents the parking plate 40c from returning to its original position, and as a result, prevents the left base cylinder 22 from rotating. In other words, by stepping on the parking brake pedal 40, the left brake pedal 12L remains applied.

[0050] <Roles of the First Check Plate 34a and the Second Check Plate 40a> The roles and relationships of the first and second check plates 34a and 40a described above will now be explained. As shown in FIG. 3, the first check plate 34a is a roughly V-shaped plate, fixed to a cylinder 34b at approximately its center. On the other hand, the second check plate 40a is an arc-shaped plate, fixed to a cylinder member 40e on its inner periphery. The cylinder member 40e and the cylinder 34b are arranged parallel to each other. Note that the first check plate 34a, the second check plate 40a, and other components may be combined into a single unit, and this unit may be installed at the lower left of the dash panel. This allows for space savings.

[0051] 3, a first protrusion 34a1 is formed at the lower left end of the first check plate 34a, and a first recess 34a2 is formed to the right of that. On the other hand, a second protrusion 40a1 is formed at the upper left end of the second check plate 40a, and a second recess 40a2 is formed to the right of that.

[0052] In the state shown in Figure 3, the release lock lever 34 is lowered to the lower side, so that the release lock state is established, which restricts (prohibits) the operation of the pedal release operation unit 30 to release the connection, and the parking brake pedal 40 is not depressed.

[0053] In this state, neither convex portion is under the other's concave portion, and as a result, from this state, the operator can freely choose to either raise the operating portion 34d of the release lock lever 34 to rotate the first check plate 34a and operate the pedal uncoupling operating portion 30 to release the coupling, or depress the parking brake pedal 40 to rotate the second check plate 40a and park the vehicle.

[0054] 4 shows the state in which the parking brake pedal 40 is depressed to park the vehicle from that state. In this case, the second protrusion 40a1 of the second check plate 40a rotates clockwise in response to the depression of the pedal, and moves below the first recess 34a2 of the first check plate 34a.

[0055] As a result, even if an attempt is made to raise the release lock lever 34 in this state to enable uncoupling (to release the prohibition on uncoupling), the first recess 34a2 comes into contact with the second protrusion 40a1, preventing it from being rotated. In other words, when the parking brake pedal 40 is depressed to park the vehicle, it is not possible to enable uncoupling.

[0056] With this structure, simply depressing the parking brake pedal 40 allows parking and simultaneously prohibits the vehicle from entering a state in which it can be uncoupled, so two effects can be achieved with one action, which is convenient and eliminates the worry of forgetting to prevent the vehicle from entering a state in which it can be uncoupled.

[0057] 5 shows a case where, from the freely selectable state in FIG. 3, the release lock lever 34 is raised to pull up the rod portion 34e, thereby rotating the base end portion 30b of the pedal uncoupling operation unit 30 by a certain amount to set it in a state where it can be uncoupled (the base end portion 30b is rotated downward by a certain amount). In this case, the first check plate 34a rotates counterclockwise in response to the rise of the release lock lever 34, so that the first protrusion 34a1 fits onto the second recess 40a2 of the second check plate 40a on the parking brake pedal 40 side.

[0058] Therefore, in such a state where uncoupling is possible (state where uncoupling prohibition has been lifted), even if an attempt is made to further depress the parking brake pedal 40, the first convex portion 34a1 gets in the way, preventing the second restraining plate 40a from rotating clockwise, and parking is therefore prohibited.

[0059] In this structure, simply by moving the release lock lever 34, the connection can be released and at the same time the parking brake pedal 40 can be prevented from being depressed, so two effects can be achieved with one action, which is convenient and eliminates the worry of forgetting to prohibit parking.

[0060] FIG. 6 shows a state in which the left and right brake pedals 12L, 12R are released from the uncoupling state shown in FIG. 5 by stepping down the pedal portion 30a of the pedal uncoupling operation unit 30 and pulling down the wire 28.

[0061] The first and second check plates 34a and 40a are one example of the check device of the present invention, and the shape and positional relationship of the first and second check plates 34a and 40a are not necessarily limited to the example described above. In short, when the release lock lever 34 is in the downward position and in the release lock state, and the parking brake pedal 40 is not depressed, the two check plates need only be positioned so that they do not interfere with each other, and so that if one check plate moves, the other check plate cannot move. For example, crescent-shaped plates could be used.

[0062] The following will explain specific working and non-working states.

[0063] <When driving on the road> Normally, since one-sided braking is dangerous on the road, the left and right brake pedals 12L, 12R are left connected when driving. That is, at the pedal connecting portion 25, the connecting piece 26 rotates around the rotating shaft 26a, and the tip of the connecting piece 26 fits into the hook-shaped receiving portion 27, connecting the left and right arms 23, 23.

[0064] In this state, the left and right brake pedals 12L and 12R are connected to each other, so there is no need to worry about sudden rotation even if you press only one of them.

[0065] Also, since there is no particular need to release the connection and it would be dangerous to do so, the operating portion 34d of the release lock lever 34 is pressed down to prohibit the release operation of the pedal connection release operating portion 30.

[0066] Therefore, as described above, in the state shown in FIG. 3, the parking brake pedal 40 can be depressed and the vehicle can be parked.

[0067] Furthermore, when the vehicle is parked, the second check plate 40a is rotated, so even if you try to move the operating portion 34d of the release lock lever 34 upward to make it possible to uncouple, the movement of the first check plate 34a is restrained by the second check plate 40a, so it cannot move upward and the release lock remains engaged, preventing the uncoupling operation using the pedal uncoupling operating portion 30. As a result, for example, when parking on a slope, a dangerous situation where only the left brake is applied due to uncoupling can be avoided.

[0068] <When driving straight in a field> When going straight, the process is the same as when driving on the road.

[0069] <When turning while traveling in a field> First, the pedal is released from the coupling state in order to turn. That is, the operation part 34d of the release lock lever 34 is moved upward to enable the release of the coupling. At the same time, the first check plate 34a rotates. Then, the pedal is released from the coupling state by the pedal release operation part 30 (see Figure 6).

[0070] In this case, even if you try to depress the parking brake pedal 40, the movement of the second check plate 40a is restrained by the first check plate 34a, and you cannot park in this state. Therefore, there is no need to worry about parking with one brake engaged when turning. [Industrial Applicability]

[0071] The present invention is highly safe and is ideal for tractors because it prevents one-sided braking when parking on a slope, etc. [Explanation of symbols]

[0072] 1 Tractor 2. Bonnet 3 Transmission case 4, 5 Front and rear wheels 7. Cockpit 10. Accelerator pedal 11. Clutch pedal 12 Brake pedal 12L, 12R left and right brake pedals 13 PTO shaft 22 Left base barrel 22' right base barrel 23 Left and right arms 24 biasing member 25 Pedal connection part 26 Connecting piece 27 Receiving part 28 wires 30 Pedal disconnection operation section 30a Pedal section 30b Proximal end 30c Push Bar 30d hole 30e Rotation center 31 Wire Plate 31a axis 31b Release pin 34 Release lock lever 34a First check plate 34a1 First convex part 34a2 First recess 34a3 hole 34b tube 34c Guide Plate 34d operation section 34e Rod section 34f bottom end 34g guide groove 37 Pedal coupling operation detection switch 38 Lock operation detection switch 40 Parking brake pedal 40a Second check plate 40a1 Second convex part 40a2 Second recess 40b axis 40c parking board 40d plate 40e Cylinder member E-Engine

Claims

1. Left and right braking devices for braking the left and right rear wheels, respectively; left and right brake pedals for operating the left and right braking devices, respectively; a pedal disconnection operation unit that can disconnect the left and right brake pedals by stepping on it; a release lock lever that can prohibit the pedal release operation unit from releasing the coupling, and can also cancel this prohibition; a parking brake device that keeps one of the left and right brake pedals in a depressed state; a restraining device that prevents an operation to activate the parking brake device and an operation to release the prohibition of the pedal disconnection operation unit by the release lock lever from being performed simultaneously, The restraining device is a first check plate that is interlocked with the operation of the release lock lever; a second check plate that is interlocked with the operation of the parking brake device, When the release lock lever is operated to release the prohibition of the coupling release operation of the pedal coupling release operation unit, the first check plate abuts against the second check plate to restrict the operation of the parking brake device, When an operation to activate the parking brake device is performed, the second restraining plate abuts against the first restraining plate, thereby restricting the operation of canceling the prohibition on the disconnection operation of the pedal disconnection operating unit by the release lock lever.

2. The first check plate has a first recess and a first protrusion, and rotates in conjunction with the operation of the release lock lever. the second check plate has a second recess and a second protrusion, and rotates in conjunction with the operation of the parking brake device; When the release lock lever prohibits the release operation of the pedal release operation unit and the parking brake device is not depressed, the first protrusion of the first check plate does not enter the second recess of the second check plate, and the second protrusion of the second check plate does not enter the first recess of the first check plate, When the prohibition on the disconnection operation of the pedal disconnection operation unit is lifted by the release lock lever, the first convex portion of the first check plate enters the second concave portion of the second check plate, thereby preventing the second check plate from moving and restricting the operation of the parking brake device.

2. The work vehicle according to claim 1, wherein when the parking brake device is depressed, the second convex portion of the second restraining plate enters the first concave portion of the first restraining plate, thereby preventing the first restraining plate from moving and restricting the release lock lever from lifting the prohibition on the pedal uncoupling operation unit.

3. The release lock lever is composed of an operating part that protrudes rearward and is movable up and down, and a rod part whose tip is bent and extended downward, and the release operation of the pedal connection release operating part can be prohibited or lifted by the vertical movement of the lower end of the rod part in response to the vertical movement of the operating part, The first check plate is rotatably connected to the vehicle body frame, and the tip of the operating part is inserted into a hole formed in the rear end part of the first check plate, and the first check plate rotates in response to the up and down movement of the operating part of the release lock lever. The parking brake pedal of the parking brake device is fixed to a cylindrical member rotatably mounted on a shaft fixed to the vehicle body frame, The second check plate is attached to the cylindrical member and rotates when the parking brake pedal is depressed, The work vehicle according to claim 2 , wherein the first check plate and the second check plate are disposed opposite each other.

4. the pedal disconnection operating unit has a pedal unit, a base end portion connected to the pedal unit, and a rotation center located at a central position of the base end portion and serving as a rotation center of the pedal disconnection operating unit, An arc-shaped hole having the rotation center as its center is drilled in the base end portion, The lower end of the rod portion is engaged with the hole, The hole restricts the rotation range of the pedal disconnection operating part, 4. The work vehicle according to claim 3, wherein the position where the hole can be present varies depending on the vertical position of the lower end, and the range of rotation of the pedal disconnection operating part varies depending on the variation.

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