JP3002332B2 - Work vehicle side brake operation structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an operation structure of a side brake in a working vehicle having a pair of left and right side brakes capable of independently braking left and right rear wheels.

[0002]

2. Description of the Related Art In a work vehicle equipped with a side brake as described above, for example, as disclosed in JP-A-58-463 and JP-A-3-243429, a steering wheel and a steering mechanism are used. When the front wheel is steered to the right or left, the operation of the steering mechanism is electrically detected by a limit switch, and the control device automatically operates the side brake on the turning center side to the braking side, There is a configuration in which an operation of a steering mechanism is taken out by a cam mechanism, a control valve is switched, and a side brake on a turning center side is automatically operated to a braking side by a hydraulic cylinder.

[0003]

In the work vehicle described above, the steering mechanism and the left and right side brakes are electrically linked via a limit switch and a control device, or the hydraulic pressure is controlled by a cam mechanism, a switching valve, and a hydraulic cylinder. Therefore, many devices and mechanisms are interposed between the steering mechanism and the left and right side brakes.

As a result, the structure becomes complicated as a whole, and high-precision assembly of a device and a mechanism between the steering mechanism and the left and right side brakes is required, so that the manufacturing cost tends to be increased as a whole. Therefore, there was room for improvement in terms of simplifying the structure. A lot of mud and soil adhere to agricultural tractors that travel in paddy fields, etc., so contact failure of the limit switch, operation failure of the cam mechanism, oil leakage from the switching valve, etc. are apt to occur, and the reliability of operation is reduced. But there was room for improvement. The present invention is intended to simplify the structure and improve the reliability of operation when a steering mechanism and left and right side brakes are linked in a side brake operation structure of a work vehicle having a pair of left and right side brakes. It is an object of the present invention to suppress unnecessary influence on the side brake pedal and the steering mechanism when the steering mechanism and the left and right side brakes are linked.

[0005]

The feature of the present invention resides in the following structure in the side brake operation structure of a working vehicle as described above. [1] A steering mechanism for steering the front wheels, a pair of left and right side brake pedals, and a pair of left and right side brakes capable of independently braking the left and right rear wheels are provided. And the right or left side brake is operated to the braking side when the right or left side brake pedal is depressed. And the pair of left and right side brakes and the steering mechanism are mechanically interlocked via a second linkage mechanism, so that the side brake on the turning center side is operated to the braking side by the operating force of the steering mechanism. Is configured as
Further, the first linkage mechanism and the second linkage mechanism transmit a braking operation force by the steering mechanism and the left and right side brake pedals from the steering mechanism and the left and right side brake pedals to the left and right side brakes. In addition, there is provided an associated movement preventing means for preventing transmission from the steering mechanism side to the left and right side brake pedal sides, and transmission from the left and right side brake pedal sides to the steering mechanism side.

[2] In the above-mentioned [1], the dragging operation preventing means allows the steering mechanism to depress the right and left side brake pedals within a predetermined range and does not transmit the steering to the steering mechanism. The operation preventing means and the second entraining operation preventing means for permitting the steering operation of the front wheel by the steering mechanism to the right and left side brake pedals within a predetermined range and not transmitting the steering operation to the right and left side brake pedals. It is composed.

[3] In the above configuration [1] or [2], the second linkage mechanism is configured to be freely operable to switch between a linkage state and a linkage release state.

[4] In any one of the above [1], [2] and [3], the front wheel and the rear wheel are driven at substantially the same speed in a standard state, and the front wheel is higher than the rear wheel. A front wheel transmission that can be operated in a speed-up state that is driven at a high speed. The steering mechanism and the front wheel transmission are mechanically interlocked via a third linkage mechanism, and the front wheel is turned right or left by the steering mechanism. When the steering operation is performed, the front wheel transmission is operated from the standard state to the speed-up state by the operating force of the steering mechanism via the third linkage mechanism.

[0009]

[I] According to the features of claims 1 and 2, if the front wheel is steered to the right by the steering mechanism, for example, the right side (turn center side) is operated by the operating force of the steering mechanism via the second linkage mechanism. Is automatically operated to the braking side, and a small turning right can be performed by the braking action on the rear wheel on the right side (the turning center side).

In this case, since the steering mechanism and the left and right side brakes are mechanically linked by the second link mechanism, the operating force of the steering mechanism is applied to the side brakes regardless of the adhesion of mud or dirt. The transmission is reliably performed, and the side brake on the turning center side is reliably operated on the braking side. According to the features of claims 1 and 2, there is no need to intervene many devices and mechanisms (such as limit switches and control devices, cam mechanisms, switching valves and hydraulic cylinders) between the steering mechanism and the left and right side brakes. So
According to the features of claims 1 and 2, the overall structure is simpler than the electric or hydraulic linkage as described in "Prior Art" and "Problems to be Solved by the Invention" As a result, the assembly of the device and the mechanism between the steering mechanism and the left and right side brakes is simplified.

According to the first and second aspects of the present invention, if the driver operates the right or left side brake pedal without operating the front wheel to the right or left by the steering mechanism, the first linkage mechanism can be operated. By the action, the right or left side brake is operated to the braking side. According to the features of the first and second aspects, when the side brake on the turning center side cannot be sufficiently operated to the braking side only by the operating force of the steering mechanism alone, or when the operation of the steering mechanism becomes heavy, By depressing the brake pedal, the depressing operation force of the side brake pedal can be added to the operation force of the steering mechanism, so that the side brake on the turning center side can be lightly and sufficiently operated on the braking side.

[II] According to the features of claims 1 and 2, if the right or left side brake pedal is depressed in a state where the steering operation of the front wheels is not performed by the steering mechanism, the operation of the first linkage mechanism is performed. , The right or left side brake is operated to the braking side, and the depressing operation of the right or left side brake pedal causes the steering mechanism to act on the steering mechanism by the operation of the drag operation preventing means (first drag operation preventing means). Is not transmitted. Thus, the steering mechanism is not operated by depressing the right or left side brake pedal. As described above, even if the right or left side brake pedal is depressed, the steering mechanism is not operated, so that the right or left side brake is braked by depressing the right or left side brake pedal. The operation to the side can be performed lightly without becoming heavy due to the operation resistance of the steering mechanism. In addition, by the action of the dragging operation inhibiting means (second dragging operation inhibiting means),
It is also possible to prevent the side brake pedal from operating when the steering mechanism is operated. Even if the front wheels are steered to the right or left by the steering mechanism, the right and left side brake pedals are not operated. Therefore, the right or left side brakes on the braking side of the front wheels are steered by the steering mechanism. Can be lightened without becoming heavy due to the resistance of the right and left side brake pedals.

[III] According to the second aspect of the present invention, in addition to the operations described in the above [I] and [II], the dragging operation preventing means includes a first dragging operation preventing means and a second dragging operation preventing means. , It is possible to simplify the structure of the individual drag operation preventing means.

[IV] According to the feature of the third aspect, similar to the case of the first or second aspect, the "action" described in the above-mentioned [I] to [III] is provided. It has various “actions”.
As described in the preceding section [I], when a small turning is performed by braking the rear wheel on the turning center side, depending on the state of the ground,
The rear wheel on the turning center side (braking side) may be dragged on the ground, and the ground may be roughened by the rear wheel on the turning center side (braking side).

According to a third aspect of the present invention, if the second linking mechanism is switched to the disengaged state in such a case as described above, even if the front wheel is steered to the right or left by the steering mechanism, the turning center side is attained. Since the side brake is not operated on the braking side, it does not mess with the ground. Furthermore, stable running can be maintained during non-working running or running on the road where it is not necessary to apply braking to the rear wheel on the turning center side.

[V] According to the feature of claim 4, similarly to the case of any one of claims 1, 2, and 3, it has the functions of the above-mentioned [I] to [IV], In addition, it has the following “action”. According to the fourth aspect of the present invention, there is provided a front wheel transmission operable in a standard state in which the front wheels and the rear wheels are driven at substantially the same speed, and in a speed increasing state in which the front wheels are driven at a higher speed than the rear wheels. The steering mechanism and the front wheel transmission are mechanically linked to each other via a third linkage.

Thus, when the front wheel is steered to the right, for example, by the steering mechanism, the steering wheel is operated by the operating force of the steering mechanism via the second linking mechanism to the right (turning center side).
Is automatically operated to the braking side, and the front wheel transmission is automatically operated from the standard state to the speed increasing state by the operating force of the steering mechanism via the third linkage mechanism. Accordingly, a small right turn can be smoothly performed by the braking action on the rear wheel on the right side (the turning center side) and the pulling action of the front wheel in the speed increasing state in the turning direction by the front wheel transmission.

In this case, since the steering mechanism and the front wheel transmission are mechanically interlocked by the third link mechanism, the operating force of the steering mechanism is reliably applied to the front wheel transmission regardless of the adhesion of mud or dirt. And the front wheel transmission is reliably operated from the standard state to the speed increasing state. According to the feature of claim 4, there is no need to intervene many devices and mechanisms (such as limit switches and control devices, cam mechanisms, switching valves and hydraulic cylinders) between the steering mechanism and the front wheel transmission. According to the feature of the item 4, the structure is simplified as a whole, and the assembly of the device and the mechanism between the steering mechanism and the front wheel transmission is simplified.

[0019]

According to the first and second aspects of the present invention, the steering mechanism and the left and right side brakes are mechanically linked to each other by the second link mechanism, regardless of the adhesion of mud or soil. With the operating force of the steering mechanism, the side brake on the turning center side is reliably operated on the braking side, and the operation reliability can be increased. According to the features of claims 1 and 2, the structure can be simplified as a whole as compared with the electric linkage or the hydraulic linkage, and the device between the steering mechanism and the left and right side brakes. In addition, the assembly of the mechanism can be simplified, which is advantageous in terms of manufacturing cost.

According to the first and second aspects of the present invention, apart from the operation of the side brake on the turning center side by the steering mechanism on the braking side, the operation of the right and left side brake pedals on the braking side of the side brake is performed. Since the operation can be performed as before, the operability at the time of turning is good in this point. Furthermore, when the steering mechanism is operating the side brake on the turning center side to the braking side, when the operating force of the steering mechanism alone cannot sufficiently operate the side brake on the turning center side to the braking side, or when the steering mechanism is operated. If the driver becomes heavier, depress the side brake pedal on the turning center side, and then apply the depressing operation force of the side brake pedal to the operating force of the steering mechanism, and lightly and sufficiently operate the turning brake on the turning center side to the braking side. Therefore, the operability at the time of turning can be further improved.

According to the first and second aspects of the present invention, by depressing the right and left side brake pedals from being transmitted to the steering mechanism, the right and left side brake pedals can be depressed by the steering mechanism. No longer interferes with the steering operation of the front wheels due to the above, and the reliability of the operation can be further improved. Further, since the side brake pedal is not operated when the steering mechanism is operated, the operation of the right or left side brake to the braking side by the steering operation of the front wheels by the steering mechanism is not performed on the right and left side brakes. Due to the resistance of the brake pedal, the operation can be performed lightly without becoming heavy, and the operability can be further improved.

According to the second aspect of the present invention, the drag operation preventing means is constituted by a combination of the first drag operation preventing means and the second drag operation preventing means, thereby simplifying the structure of each drag operation preventing means. Therefore, there is an effect that the manufacturing process can be simplified easily.

According to the features of claim 3, claim 1 or 2
"Effects of the Invention" of Claim 1 or 2 as in the case of
In addition to this “effect of the invention”, the following “effect of the invention” is provided. According to the third aspect of the present invention, the second linking mechanism is configured to be freely switchable to the unlinked state, thereby preventing the roughening of the ground due to the drag of the rear wheel on the braking side (the turning center side). As a result, the turning performance of the working vehicle was improved. Further, during non-working running or running on the road where there is no need to apply braking to the rear wheel on the turning center side, stable running can be maintained, and the running performance of the working vehicle can be improved.

According to the feature of claim 4, claim 1, 2, 2,
Claim 1, as in any one of the three cases
There are a few "effects of the invention", and in addition to the "effects of the invention", the following "effects of the invention" are provided. According to the feature of the fourth aspect, when the front wheel is steered to the right or left by the steering mechanism, the right or left (turn center side) side brake is automatically operated to the braking side, and the front wheel shift is performed. Since the device is automatically operated from the standard state to the speed increasing state, the braking action on the right or left side (turn center side) rear wheel, and the pulling action of the front wheel in the turning direction by the front wheel transmission in the speed increasing state. As a result, a small turning to the right or left can be smoothly performed, and the turning performance of the work vehicle can be further improved.

According to a fourth aspect of the present invention, the steering mechanism and the front wheel transmission are mechanically interlocked by the third linking mechanism, so that the steering mechanism can be operated by the operating force of the steering mechanism regardless of the adhesion of mud or soil. The front wheel transmission was reliably operated from the standard state to the speed-up state, and the operation reliability was able to be increased. According to the feature of the fourth aspect, the structure can be simplified as a whole as compared with the electric linkage or the hydraulic linkage, and the device and the mechanism between the steering mechanism and the front wheel transmission can be reduced. Since the assembling can be simplified, it is advantageous in terms of manufacturing cost.

[0026]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 11, an engine 3 is mounted on a front part of a body supported by a front wheel 1 and a rear wheel 2, and a transmission case 4 is mounted on a rear part of the body, so that an agricultural tractor as an example of a four-wheel drive type work vehicle is provided. Make up. As shown in FIG. 1, the power of the engine 3 is transmitted to a transmission (not shown) for traveling of the transmission case 4 to perform a speed change operation, and is transmitted from the rear wheel differential mechanism 5 to the left and right rear wheels 2, The power branched from the wheel differential mechanism 5 is transmitted from the front wheel transmission 7 to the left and right front wheels 1 via the front wheel transmission shaft 8 and the front wheel differential mechanism 6.

Next, the front wheel transmission 7 will be described.
As shown in FIG. 10, the power branched immediately before the rear wheel differential mechanism 5 is transmitted from the transmission gear 16 to the first standard gear 12, and transmitted through the first standard gear 12 and the transmission shaft 11 to the first speed increasing gear 13. Has been transmitted to. A second standard gear 9 and a second speed increasing gear 10 are externally fitted to the front wheel transmission shaft 8 to the front wheel 1 so as to be relatively rotatable, and the first and second standard gears 12, 9 and
And each of the second speed increasing gears 13 and 10 is engaged.

When a shift member 14 slidably attached to the front wheel transmission shaft 8 by a spline structure is engaged with the second standard gear 9, the front wheel 1 is driven at substantially the same speed as the rear wheel 2 to generate power. Is transmitted. Conversely, when the friction member 15 formed between the second speed increasing gear 10 and the front wheel transmission shaft 8 is pressed by the shift member 14 to enter the front wheel 1, the front wheel 1 is driven at a higher speed than the rear wheel 2. Power is transmitted in a speed increasing state.

Next, the structure of the operation system of the shift member 14 of the front wheel transmission 7 will be described. As shown in FIG.
A shift fork 17 of the shift member 14 is externally fitted to an operation shaft 18 slidable in the axial direction via a spring 19 for flexibility, and the shift fork 17 is weakened by a spring 20 having a smaller urging force than the spring 19. It is urged toward the occlusal side (standard state side) with the second standard gear 9. As shown in FIGS. 2 and 1,
A pitman arm 22 for steering operation of the front wheel 1 is supported by a power steering mechanism 21 (corresponding to a steering mechanism), and a cam plate 23 (corresponding to a third linkage mechanism) is fixed to the pitman arm 22 to fix the body. Cam arm 24 (third pivotally supported about the longitudinal axis P1 of the section)
A pin 24 a of the cam plate 23 is engaged with the cam hole 23 a of the cam plate 23. A wire 25 (corresponding to a third linkage mechanism) is connected between the distal end of the cam arm 24 and the operation shaft 18.

With the above structure, when the pitman arm 22 is swung from the straight traveling position to the right or left by a predetermined angle or more by operating the steering handle 26 shown in FIG. When the steering operation is performed to the right or left from the straight traveling position by a set angle or more), the cam arm 24 is swung to the left in the drawing by the cam action of the cam hole 23a and the pin 24a as shown in FIG. The wire 25 is pulled toward the cam arm 24. As a result, the operation shaft 18 and the shift fork 17 in FIG. 10 are slid to the left in the drawing, the shift member 14 presses the friction clutch 15 to perform the on operation, and the front wheel 1 is driven at an increased speed (the front wheel transmission 7). Speed increase state).

As shown in FIG. 1, a pair of left and right side brakes 27 capable of independently braking the left and right rear wheels 2 are provided. Next, the operation structure of the left and right side brakes 27 will be described. As shown in FIG. 1, a pair of brake operating mechanisms 33 is provided for a pair of left and right side brakes 27.
(Corresponding to the first linkage mechanism and the second linkage mechanism). As shown in FIGS. 5 and 6, an L-shaped brake arm 28 is swingably supported around the axis P2 by the brake operation mechanism 33. The lower end of the brake arm 28 in the drawing and the side brake 27 are connected to each other. , Each of which is linked to each other by a link rod 29 (corresponding to a first link mechanism and a second link mechanism).

As shown in FIGS. 1 and 6, a pair of left and right side brake pedals 30 are provided on the right side of the control section of the fuselage. As shown in FIGS. 28 is connected to the link rod 3
1 (corresponding to a first linking mechanism) and a linking pin 32. With the above structure, when the left side brake pedal 30 is depressed, for example, the link rod 31 is pulled upward as shown in FIG. 7, and the brake arm 28 swings counterclockwise in FIG.
9, the left side brake 27 is operated to the braking side.

Next, the left and right side brakes 27 and the front wheels 1
Of the power steering mechanism 21 will be described. As shown in FIG. 5 and FIG.
The operation arm 34 is mounted around the axis P2 of the brake arm 2.
8 is supported independently and swingably, and a link arm 36 is swingably supported around a support pin 35 at the tip of the operation arm 34. As shown in FIG. 6, a spring 37 for urging the linking arm 36 in the clockwise direction on the drawing is attached to the support pin 35, and a vertically long concave portion 36a (a dragging prevention means and 1) is formed. Thereby, the concave portion 36a of the link arm 36 is
, The connection pin 32 of the brake arm 28 enters.

As shown in FIGS. 1, 2, and 4, a right operating arm 39 is swingably supported around a longitudinal axis P3 of a right frame 38 at the front of the body, and a right brake operating mechanism 33 is provided.
The support pin 35 of the operation arm 34 and the right operation arm 39 are linked to each other by a spring 40 and a wire 41 (corresponding to a second linkage mechanism). Vertical axis P of left frame 38
A support shaft 42 is rotatably supported around 4, and a left first operation arm 43 is fixed to the upper end of the support shaft 42, and a left second operation arm 44 is fixed to the lower end. The support pin 35 of the operation arm 34 of the left brake operation mechanism 33 and the left second operation arm 44 are connected to the spring 40 and the wire 41 (second
(Corresponding to a link mechanism). A stopper 46 for stopping the right operation arm 39 and the left second operation arm 44 in the posture shown in FIG. 2 is fixed to the left and right frames 38. As shown in FIGS. 2 and 5, the operation arm 3 is attached to the support pin 35 of the operation arm 34 of the brake operation mechanism 33.
A spring 45 for urging the sheet 4 clockwise is attached.

With the above structure, for example, when the front wheel 1 is steered to the left by a predetermined angle or more, as shown in FIG. 3, the pitman arm 22 swings downward in the drawing, and the cam plate 23 moves to the left first operation position. The arm 43 comes into contact with the arm 43, and the left first and second left operation arms 43 and 44 are pivoted clockwise in the drawing. Thus, the left wire 41 is pulled toward the left first and second left operation arms 43 and 44, and the operation arm 34 of the left brake operation mechanism 33 swings counterclockwise in the drawing.
In this case, as shown in FIG.
Since the connecting pin 32 of the brake arm 28 is inserted into the connecting arm 36, the concave portion 36a and the connecting pin 3
The brake arm 28 is also pivoted counterclockwise by the engagement with the brake pedal 2, and the left side brake 27 is operated to the braking side.

As described above, when one of the side brakes 27 is operated to the braking side by the steering operation of the front wheel 1, the wire 25 is pulled by the action of the cam plate 23 and the cam arm 24 shown in FIG. As described above, the front wheel transmission 7 is operated from the standard state to the speed increasing state. As described above, when the front wheel 1 is steered to the right or left by more than the set angle, the front wheel transmission 7 is operated from the standard state to the speed-up state, and the front wheel 1 is speed-up driven, and the right or left brake operation mechanism is operated. By the operation of 33, the side brake 27 on the turning center side is operated to the braking side.

As shown in FIG. 2, both ends of the outer 41a of the left and right wires 41 are fixed to a fixed bracket 54 by a pair of nuts 47, respectively.
It is configured so that the fixed position of the can be adjusted. As described above, the initial position of the spring 40 is changed and adjusted by adjusting the fixing position of the outer 41a, and the pulling operation force of the wire 41 when the front wheel 1 is steered to the right or left by more than the set angle is changed. , So that the braking force of the side brake 27 can be adjusted.

As shown in FIGS. 5 and 6, a long hole 31a (corresponding to a second movement preventing means) is provided in the linkage rod 31 on the side brake pedal 30, and the connecting pin 32 is inserted into the long hole 31a. ing. As a result, even if the front arm 1 is steered to the right or left by more than the set angle as described above, and the operation arm 34 and the brake arm 28 swing counterclockwise as shown in FIG. By simply moving the connecting pin 32 upward through the hole 31a, the side brake pedal 30
Is not operated.

In the state shown in FIG. 2 (the state in which the wire 41 is not being pulled in the straight traveling state), when the side brake pedal 30 is depressed to move the link rod 31 upward in the drawing, as shown in FIG. When the brake arm 28 swings counterclockwise in the drawing and the connecting pin 32 moves only upward in the drawing in the concave portion 36a of the linking arm 36, the operating arm 34 and the linking arm 36 are shown in FIGS. It does not move in its posture.

Next, when the front wheel 1 is steered to the right or left by a set angle or more, the side brake 27 on the turning center side is automatically operated to the braking side as described above, and is not operated. The structure for switching the state will be described. As shown in FIGS. 8 and 9, around the horizontal axis P5 of the control section of the aircraft,
An L-shaped operation plate 48 in side view is swingably supported, and an operation lever 50 is fixed to the operation plate 48 at the position of the horizontal axis P5. As shown in FIGS. 1, 2, and 8, a pair of wires 51 is connected to each of the link arms 36 of the left and right brake operation mechanisms 33 and the operation plate 48, and the operation plate 48 and the operation lever 50 are connected. , ON shown in FIG.
A toggle spring 52 for holding the position and the OFF position, and a stopper 49 are provided.

The state shown in FIG. 8 is a state in which the operation lever 50 and the operation plate 48 are operated to the ON position. As shown in FIG. 2, the linking arms 36 of the left and right brake operation mechanisms 33 move clockwise in FIG. By the swing operation, the connecting pin 3 on the brake arm 28 side is inserted into the concave portion 36a of the link arm 36.
2 is in the state.

In this state, for example, when the front wheel 1 is steered to the left by a predetermined angle or more, the operation arm 34 of the left brake operation mechanism 33 swings counterclockwise in FIG. The brake arm 28 is pivoted in a counterclockwise direction on the drawing by the engagement between the brake arm 28 and the connecting pin 32, and the left side brake 27 is operated to the braking side (corresponding to a linked state). As shown in FIGS. 8 and 9, a limit switch 53 for detecting a state where the operation lever 50 and the operation plate 48 are operated to the ON position is provided, and a lamp (not shown) which is turned on in accordance with this detection is provided. ) Is provided.
Thus, the driver can recognize that the steering operation of the front wheel 1 to the right or left by more than the set angle automatically brakes the side brake 27 on the turning center side.

When the operating lever 50 and the operating plate 48 are operated to the OFF position, the pair of wires 51 is pulled toward the operating plate 48, and as shown by a two-dot chain line in FIG. 36 is pivoted in the counterclockwise direction on the paper surface, so that the concave portion 36a of the link arm 36 moves away from the connection pin 32 on the brake arm 28 side to the right in the paper surface. In this state, for example, even if the front wheel 1 is steered to the left by a set angle or more, the operation arm 34 of the left brake operation mechanism 33 only swings counterclockwise in the drawing, and the brake arm 28
Is not operated in the counterclockwise direction on the paper surface, and the left side brake 27 is not operated on the braking side (corresponding to the linkage release state).

[Another Embodiment] In the embodiment shown in FIG. 6, the linking arm 36 is supported at the tip of the operating arm 34 and the connecting pin 32 is attached to the tip of the brake arm 28. The connection pin 32 may be attached to the tip of the operation arm 34, and the linkage arm 36 may be supported at the tip of the brake arm 28. In this case, the link rod 31 on the side brake pedal 30 side
Is connected to the brake arm 28 by another connecting pin instead of the connecting pin 32 on the operation arm 34 side. In the above-described embodiment, the power steering mechanism 21 of a hydraulic type or the like is provided for steering operation of the front wheel 1. However, instead of such a power steering type, a normal steering mechanism without a power assist function is provided. May be equipped for steering operation of the vehicle.

Incidentally, reference numerals are written in the claims for convenience of comparison with the drawings, but the present invention is not limited to the configuration of the attached drawings by the entry.

[Brief description of the drawings]

FIG. 1 is a plan view showing a linked state of a front wheel power steering mechanism, a front wheel transmission, and left and right side brakes.

FIG. 2 shows a state in which a front wheel is operated to a straight-ahead position;
Plane and side views showing the linked state of the front wheel power steering mechanism and the left and right brake operation mechanisms

FIG. 3 is a plan view and a side view showing a linked state between a power steering mechanism of the front wheel and left and right brake operating mechanisms when the front wheel is steered to the left by a set angle or more.

4 is a rear view of the vicinity of the power steering mechanism for the front wheels in FIG. 2 as viewed from the right side in FIG. 2;

FIG. 5 is a rear view of the vicinity of the brake operating mechanism in FIG. 2 as viewed from the right side in FIG. 2;

FIG. 6 is a side view showing a linked state of left and right brake operation mechanisms, left and right side brakes, and a side brake pedal.

FIG. 7 is a side view showing a state in which the side brake pedal is depressed from the state shown in FIG. 6;

FIG. 8 is a side view of the vicinity of an operation lever for switching the front wheel power steering mechanism and the left and right brake operation mechanisms to a linkage and a linkage release state.

9 is a view of the vicinity of the operation lever in FIG. 8 as viewed from below the paper surface.

FIG. 10 is a longitudinal sectional side view of the front wheel transmission.

FIG. 11 is an overall side view of the agricultural tractor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Front wheel 2 Rear wheel 7 Front wheel transmission 21 Steering mechanism 23,24,25 Third link mechanism 27 Side brake 30 Side brake pedal 29,31,33 First link mechanism 29,33,41 Second link mechanism 31a Second link Operation blocking means 36a Dragging action blocking means, first dragging action blocking means

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-58-463 (JP, A) JP-A-2-20462 (JP, A) JP-A-1-175579 (JP, A) JP-A-2- 175331 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B62D 11/04-11/08 B60T 7/04

Claims (4)

(57) [Claims] 1. A steering for steering a front wheel (1).
Mechanism (21) and a pair of left and right side brake pedals (3
0) and the right and left rear wheels (2) that can independently brake
A pair of left and right side brakes (27) and a pair of left and right side brakes (27).
Id brake pedal (30) and the first linkage mechanism (2
9), (31) and (33) are linked mechanically
The right or left handbrake pedal (30)
When made, the right or left side brake (27) is on the braking side
The left and right
A pair of side brakes (27) and a steering mechanism (2
1) and the second linkage mechanism (29), (33), (41)
Mechanically interlocked through the steering mechanism (2
With the operation force of 1), the side brake (2
7) is operated to the braking side, and further, the first linkage mechanisms (29), (31), (3)
3) and the second linkage mechanism (29), (33), (41)
Means the steering mechanism (21) and the left and right sides
The braking operation force by the brake pedal (30) is
(21) and left and right side brake pedals (3
0) to the left and right side brakes (27).
Left and right from the steering mechanism (21) side.
Id brake pedal (30) side and left and right side shake
From the brake pedal (30) to the steering mechanism (21)
Movement preventing means (31a, 36) for preventing transmission to
a) A side brake operation structure of a work vehicle provided with a) . 2. A drag operation preventing means (31a, 36a).
Are the right and left supports with respect to the steering mechanism (21).
Perform the depressing operation of the id brake pedal (30) within a predetermined range.
The second is not allowed to be transmitted to the steering mechanism (21).
The one- sided- movement inhibiting means (36a) and the right and left side brake pedals (30)
Of the front wheel (1) by the steering mechanism (21).
The steering operation is permitted within a predetermined range, and the right and left side
Prevents second drag operation not transmitted to rake pedal (30)
2. The side brake operation structure for a work vehicle according to claim 1, wherein the side brake operation structure comprises a means (31a) . 3. The second link mechanism (29), (33), (4).
1) A pair of left and right side brakes (27) and steering
The side brake operation structure for a work vehicle according to claim 1 or 2, wherein the switching mechanism (21) is configured to be freely switchable between a linked state and a disconnected state. 4. Operating in a standard state in which the front wheel (1) and the rear wheel (2) are driven at substantially the same speed, and in a speed-up state in which the front wheel (1) is driven at a higher speed than the rear wheel (2). A free front wheel transmission (7) is provided, and the steering mechanism (21) and the front wheel transmission (7) are connected to a third linkage mechanism (23), (24), (2).
When the front wheel (1) is steered to the right or left by the steering mechanism (21), the third linkage mechanism (23),
2. The system according to claim 1, wherein the front wheel transmission is operated from a standard state to a speed-up state by an operating force of the steering mechanism via the steering wheels. 4. The side brake operation structure for a working vehicle according to any one of the above-mentioned items.