JPH0616059A - Four wheel drive type working vehicle - Google Patents

Abstract

PURPOSE:To enable a smaller sharp turn and enable the operation with ease, in a four-wheel drive type working vehicle composed to operate to convert the front wheel gear change device into a speed increasing condition by a cam mechanism, when the cam mechanism provided on a power steering mechanism for front wheels, and the front wheel gear change device are linked and connected mechanically so as to operate to steer the front wheels at a set angle or more by the power steering mechanism. CONSTITUTION:A pair of the left and the right side brakes 27 to brake the left side and the right side rear wheels 2 independently are provided, and the cam mechanism of a power steering mechanism 21 for front wheels 1, and the left and the right side brakes 27 are linked and connected with the second cooporating mechanisms 29 and 41 respectively. As a result, the system is composed that a front wheel gear change device 7 is operated to convert into a speed increasing condition by the cam mechanism 23, and furthermore, the side brake 27 at the center side of the turning is operated to the braking side, when the front wheels 1 are operated to steer from the straight running position to the right side or the left side at a set angle or more by the power steering mechanism 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a front wheel shifting structure and a rear wheel braking structure when turning in a four-wheel drive type work vehicle.

[0002]

2. Description of the Related Art In a four-wheel drive type work vehicle as described above, as disclosed in, for example, Japanese Utility Model Laid-Open No. 1-107632, a standard state in which front wheels and rear wheels are driven at substantially equal speeds, In some cases, the front wheel transmission is provided in the transmission system to the front wheels, which can be steered, in a speed increasing state in which the front wheels are driven at a higher speed than the rear wheels, and which can be switched by sliding the shift member. As a result, the small wheel turning can be smoothly performed by switching the front wheel transmission to the speed increasing state at the time of turning to drive the front wheels to speed up.

In this case, as shown in FIG. 3 and FIG. 6 of the publication, a cam mechanism (2 in FIG. 3 of the publication) is attached to a pitman arm for the front wheel (19 in FIG. 3 of the publication).
6), the cam mechanism and the shift member of the front wheel transmission (15 in FIG. 6 of the publication) are connected by a wire (24 in FIG. 3 of the publication) (corresponding to the first linkage mechanism). When the front wheels are mechanically interlocked and connected to each other and steered from the straight ahead position to the right or left over a set angle, the front wheel transmission is switched from the standard state to the speed increasing state by the cam mechanism. Further, by equipping the power steering mechanism for the pitman arm, the steering operation of the front wheels and the switching operation of the front wheel transmission can be performed lightly by the steering wheel.

[0004]

In an agricultural tractor, which is an example of a four-wheel drive type working vehicle, a pair of left and right side brakes that can independently brake the left and right rear wheels, and a pair of left and right side brakes for the side brakes. Equipped with a side brake pedal. Therefore, if the front wheels are accelerated by the front wheel transmission during turning and the side brake pedal on the turning center side is stepped on, a small turn can be made with a smaller radius. However, during such a turning operation, the side brake pedal on the turning center side must be depressed simultaneously with the steering operation of the front wheels by the steering handle, so there is room for improvement in terms of simplifying the turning operation. An object of the present invention is to make it possible to easily perform a small turning operation using a front wheel transmission and side brakes for rear wheels, and also to make this structure simple.

[0005]

A feature of the present invention is that the four-wheel drive type working vehicle as described above is configured as follows. That is, a front wheel transmission capable of switching between a standard state in which the front wheels and the rear wheels are driven at substantially equal speeds and a speed-up state in which the front wheels are driven at a higher speed than the rear wheels can be operated by sliding the shift member. It is equipped with a transmission system to the front wheels that can be steered freely, and is equipped with a pair of left and right side brakes that can independently brake the left and right rear wheels.The power steering mechanism for the front wheels is also equipped with a cam mechanism. The shift member of the transmission is mechanically linked by a first linkage mechanism, the cam mechanism and the left and right side brakes are linked by a second linkage mechanism, and the power steering mechanism shifts the front wheels from the straight ahead position to the right or When the steering operation is performed to the left over the set angle, the cam mechanism switches the front wheel transmission from the standard state to the speed increasing state, and the side brake on the turning center side is operated to the braking side. It is the sea urchin configuration.

[0006]

With the configuration of the present invention, it is assumed that the power steering mechanism steers the front wheels from the straight-ahead position to the right, for example, at a set angle or more. In this case, the front wheel transmission is mechanically switched from the standard state to the speed increasing state by the action of the cam mechanism and the first and second linkage mechanisms, and the right side brake is also mechanically operated to the braking side. It As a result, a small turn can be made with a small radius due to the speed-up action of the front wheels and the braking action on the rear wheels on the turning center side. In this case, only by performing the steering operation of the front wheels with the steering wheel, the switching operation of the front wheel transmission to the speed increasing state and the operation of the side brake on the turning center side to the braking side are performed, so that the conventional structure is used. It is not necessary to depress the side brake pedal on the turning center side.

Then, a second linkage mechanism for linking the cam mechanism and the side brakes is simply added to the existing power steering mechanism and cam mechanism (for front wheel transmission). The structure of the present invention can be easily obtained without modification. Further, if a power steering mechanism having a sufficient operating force is provided, even if the power steering mechanism is configured to operate both the front wheel transmission and the side brake as in the present invention, the operation of the steering wheel is heavy. And the operability is not deteriorated.

[0008]

As described above, the operation of switching the front wheel transmission to the speed increasing state and the operation of the side brake on the turning center side to the braking side are automatically performed only by operating the steering wheel. Since it is not necessary to step on the side brake pedal during turning, the turning operation can be simplified and the turning operability can be improved. Further, by using the power steering mechanism having the existing structure for operating both the front wheel transmission and the side brake, the configuration of the present invention can be easily obtained by a slight addition or modification, so that the manufacturing cost is reduced. But it will be an advantage.

[0009]

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 the front of the machine supported by front wheels 1 and rear wheels 2, and a mission case 4 is mounted on the rear of the machine to configure an agricultural tractor that is an example of a four-wheel drive work vehicle. is doing. As shown in FIG. 1, motive power from the engine 3 is transmitted to a traveling transmission (not shown) in 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. In addition, the power branched from the rear 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 from immediately before the rear wheel differential mechanism 5 is transmitted from the transmission gear 16 to the first standard gear 12, and the first standard gear 12 and the transmission shaft 11 are used to drive the first power.
It is transmitted to the speed increasing gear 13. A second standard gear 9 and a second speed increasing gear 10 are fitted to the front wheel transmission shaft 8 to the front wheel 1 so as to be rotatable relative to each other, and the first and second standard gears 12, 9,
Each of the first and second speed increasing gears 13, 10 is in mesh.

A second shift member 14 is slidably attached to the front wheel transmission shaft 8 by a spline structure.
When engaged with the standard gear 9, power is transmitted in a state where the front wheel 1 is driven at substantially the same speed as the rear wheel 2 (standard state). On the contrary, when the friction clutch 15 formed between the second speed increasing gear 10 and the front wheel transmission shaft 8 is pressed and operated by the shift member 14, the front wheel 1 is driven at a higher speed than the rear wheel 2. Power is transmitted (acceleration 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.
The shift fork 17 for the shift member 14 is externally fitted to the operation shaft 18 that is slidable in the axial direction via a spring 19 for accommodation, and the spring 20 having a weaker biasing force than the spring 19 causes the shift fork 17 to move. It is urged toward the side of engagement with the second standard gear 9 (standard state side). On the other hand, as shown in FIGS. 2 and 1, the power steering mechanism 21 supports the pitman arm 22 for steering operation of the front wheels 1, and the cam plate 23 (corresponding to the cam mechanism) is fixed to the pitman arm 22. The pin 24a of the cam arm 24, which is swingably supported around the vertical axis P1 of the machine body fixing portion, is attached to the cam plate 2
3 is engaged with the cam hole 23a. And wire 2
5 (corresponding to the first linkage mechanism) is connected across the tip of the cam arm 24 and the operation shaft 18.

With the above structure, when the steering handle 26 shown in FIG. 11 is operated and the power steering mechanism 21 swings the pitman arm 22 from the straight-ahead position to the right or the left over a set angle, that is, the front wheel 1 When the steering wheel is steered to the right or left from the straight-ahead position over the set angle, the cam arm 24 is swung to the left side of the drawing by the cam action of the cam hole 23a and the pin 24a as shown in FIG.
The wire 25 is pulled to the cam arm 24 side. 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, and the front wheel 1 is accelerated.

As shown in FIG. 1, a pair of left and right side brakes 27 that can independently brake 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 are provided for the pair of left and right side brakes 27. As shown in FIGS. 5 and 6, an L-shaped brake arm 28 is swingably supported around the axis P2 in the brake operating mechanism 33, and the lower end of the brake arm 28 on the paper surface and the side brake 27 are connected to each other. Are linked together by link rods 29 (corresponding to 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 machine body. As shown in FIGS.
0 and one end of the brake arm 28 are interlockingly connected by a connecting rod 31 and a connecting pin 32. With the above structure, for example, when the left side brake pedal 30 is stepped on, the link rod 31 is pulled upward in the drawing as shown in FIG. Thus, the left side brake 27 is operated to the braking side.

Next, the left and right side brakes 27 and the front wheels 1
The cooperation with the power steering mechanism 21 for vehicle will be described. As shown in FIGS. 5 and 6, the brake operating mechanism 3
The operation arm 34 is independently swingably supported with respect to the brake arm 28 around the axis P2 of the third arm 3, and the linkage arm 36 is provided around the support pin 35 at the tip of the operation arm 34.
Is swingably supported. As shown in FIG. 6, a spring 37 for urging the linking arm 36 in the clockwise direction on the paper surface is attached to the support pin 35, and a vertically long concave portion 36a is formed on the left side of the linking arm 36 on the paper surface. As a result, the connecting pin 32 of the brake arm 28 is inserted into the recess 36a of the linking arm 36 by the urging force of the spring 37.

As shown in FIGS. 1, 2, and 4, a right operation arm 39 is swingably supported around a vertical axis P3 of a right frame 38 at the front of the machine body, and a right brake operation mechanism 33 is provided.
The support pin 35 of the operation arm 34 and the right operation arm 39 are interlockingly connected by a spring 40 and a wire 41 (corresponding to a second linkage mechanism). Vertical axis P of the left frame 38
4, a support shaft 42 is rotatably supported, 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. Then, the support pin 3 of the operation arm 34 of the left brake operation mechanism 33
5 and the left second operation arm 44, the spring 40 and the wire 4
1 (corresponding to the second linkage mechanism) is linked.
A stopper 46 for stopping the right operation arm 39 and the left second operation arm 44 in the posture shown in FIG.
It is fixed to. Further, as shown in FIGS. 2 and 5, the support pin 35 of the operation arm 34 of the brake operation mechanism 33 is used.
The spring 4 for urging the operation arm 34 clockwise in the drawing.
5 is attached.

With the above structure, when the front wheel 1 is steered to the left by more than the set angle, the pitman arm 22 swings downward as shown in FIG. 3, and the cam plate 23 moves to the left first operation. The left first and left second operation arms 43, 44 are brought into contact with the arm 43, and the left first and second left operation arms 43, 44 are oscillated in the clockwise direction of the drawing. As a result, the left wire 41 is pulled toward the first left 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 in a, the linkage arm 36 is moved along with the swing of the operation arm 34.
When is pulled up above the paper surface, the brake arm 28 is also swung counterclockwise on the paper surface due to the engagement between the concave portion 36a and the connecting pin 32, and the left side brake 27 is operated toward 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 wheels 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 switched from the standard state to the speed increasing state. As described above, when the front wheels 1 are steered by the set angle or more, the front wheel transmission 7 is switched to the speed increasing state and the front wheels 1 are driven to speed up, and by the action of the right or left brake operating mechanism 33, The side brake 27 of the rear wheel 2 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 the fixed bracket 54 by a pair of nuts 47, respectively, and the outer 41a is fixed.
It is configured so that the fixed position of can be adjusted. In this way, the fixed position of the outer 41a is adjusted to change / adjust the initial tension of the spring 40, and the pulling operation force of the wire 41 when the front wheel 1 is steered over a set angle or more is changed, and the side brakes are changed. The braking force of 27 can be adjusted.

As shown in FIGS. 5 and 6, the link rod 31 on the side brake pedal 30 side is provided with a long hole 31a, and the connecting pin 32 is inserted into the long hole 31a. As a result, even if the front wheel 1 is steered over the set angle as described above and the operation arm 34 and the brake arm 28 swing counterclockwise in the drawing as shown in FIG.
The side brake pedal 30 is not operated, only the connecting pin 32 moves upward in the drawing.

In addition, the state shown in FIG.
1 in a state where the pulling operation is not performed), when the side rod pedal 30 is stepped on and the linking rod 31 is moved upward in the drawing, as shown in FIG.
8 swings counterclockwise in the drawing, the connecting pin 32 only moves upward in the recess 36a of the linking arm 36 in the drawing, and the operating arm 34 and the linking arm 36 are not shown in FIGS.
It does not move in the posture shown in.

Next, when the front wheels 1 are steered over a set angle, the side brakes 2 on the turning center side as described above.
A switching structure between a state where 7 is automatically operated to the braking side and a state where it is not operated will be described. As shown in FIGS. 8 and 9, an operation plate 48 having an L-shape in a side view is swingably supported around a horizontal axis P5 of the control portion of the machine body.
The operation lever 50 is fixed to the position of the horizontal axis P5 in FIG. As shown in FIGS. 1, 2, and 8, a pair of wires 51 are connected across each of the linkage arms 36 of the left and right brake operating mechanisms 33 and the operating plate 48, and the operating plate 4
8 and operating lever 50 to the ON position and OFF shown in FIG.
Toggle spring 52 and stopper 49 held in position
Is 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 linkage arms 36 of the left and right brake operation mechanisms 33 move clockwise in the drawing. This is a state in which the connecting pin 32 on the brake arm 28 side is inserted into the recess 36a of the linking arm 36 by being rocked.

In this state, for example, when the front wheel 1 is steered to the left by more than the set angle, the operating arm 34 of the left brake operating mechanism 33 swings counterclockwise in the drawing as shown in FIG. The brake arm 28 is oscillated counterclockwise in the drawing by the engagement of the connection pin 32 with the connection pin 32, and the left side brake 27 is operated toward the braking side. In this case, as shown in FIGS. 8 and 9, the operation lever 50 and the operation plate 48 are
Is provided with a limit switch 53 for detecting a state of being operated to the ON position, and a lamp (not shown) that is turned on in response to the detection is provided. This allows
The operator can recognize that if the front wheel 1 is steered over the set angle, the side brake 27 on the turning center side is automatically braked.

Then, when the operating lever 50 and the operating plate 48 are operated to the OFF position, the pair of wires 51 are moved to the operating plate 4
8 and the linkage arms 36 of the left and right brake operating mechanisms 33 are oscillated counterclockwise in the drawing as shown by the chain double-dashed line in FIG. 6, so that the recess 36a of the linkage arm 36 moves toward the brake arm 28 side. The connecting pin 32 is moved to the right side of the drawing. 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 operating mechanism 33 only swings counterclockwise on the paper surface, and the brake arm 28 rotates counterclockwise on the paper surface. The left side brake 27 is not operated toward the braking side.

It should be noted that reference numerals are given in the claims for convenience of comparison with the drawings, but the present invention is not limited to the configurations of the accompanying drawings by the entry.

[Brief description of 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] In a state where the front wheels are operated in a straight ahead position,
A plan view and a side view showing a state in which the power steering mechanism for the front wheels and the left and right brake operating mechanisms are linked to each other.

FIG. 3 is a plan view and a side view showing a state in which the power steering mechanism for the front wheels and the left and right brake operating mechanisms are linked to each other when the front wheels are steered to the left over a set angle.

FIG. 4 is a rear view of the vicinity of the front wheel power steering mechanism in FIG. 2 as viewed from the right side of the paper surface of FIG.

5 is a rear view of the vicinity of the brake operation mechanism in FIG. 2 as viewed from the right side of the paper surface of FIG.

FIG. 6 is a side view showing a state in which the left and right brake operation mechanisms are linked with the left and right side brakes and side brake pedals.

7 is a side view showing a state in which the side brake pedal is stepped on from the state shown in FIG.

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 operating mechanisms to a linked state and a linked state.

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

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

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

[Explanation of symbols]

 1 Front Wheel 2 Rear Wheel 7 Front Wheel Transmission 14 Shift Member 21 Power Steering Mechanism 23 Cam Mechanism 25 First Linkage Mechanism 27 Side Brake 29,41 Second Linkage Mechanism

Claims (1)

[Claims] 1. A standard state in which the front wheels (1) and the rear wheels (2) are driven at substantially equal speeds and a speed-up state in which the front wheels (1) are driven at a higher speed than the rear wheels (2), Shift member (1
4) A front wheel transmission (7) that can be switched by sliding operation is provided in the transmission system to the front wheel (1) that can be steered, and the left and right rear wheels (2) can be independently braked independently. Equipped with side brakes (27) and front wheels (1)
Power steering mechanism (21) for the cam mechanism (2
3), the cam mechanism (23) and the shift member (14) of the front wheel transmission (7) are connected to the first linkage mechanism (2).
5) mechanically interlockingly connected by the cam mechanism (23)
And the left and right side brakes (27) between the second linkage mechanism (2
When the front steering wheel (1) is steered by the power steering mechanism (21) from the straight-ahead position to the right or left by a predetermined angle or more, the cam mechanism (23) causes A four-wheel drive work vehicle configured such that the front wheel transmission (7) is switched from a standard state to a speed-up state and the side brake (27) on the turning center side is operated to a braking side.