JPH08116735A - Frame-lifting device in paddy field working machine - Google Patents

Abstract

PURPOSE: To reduce the load of a lifting or lowering operation lever for switching a hydraulic switch valve to lower the costs of interlocking members. CONSTITUTION: When a paddy field work vehicle reaches the end of a paddy field, a swinging member 71 is swung by the operation of a work clutch lever. When a handle 36 is lifted in the state to operate a float 11 in the direction for increasing the sensing of soil pressure, the float 11 interlocks an operation arm 10a to a lifting position through interlocking members 12, 22, 23, 26. A spring 93 for energizing the swinging member 71 in the direction opposite to the movement of an operation arm 10a to a lifting position is connected between the operation arm 10a and the swinging member 71. The swinging member 71 is swung in the direction not causing the change in the energization force of the spring 93 in response to the movement of the operation position of the operation arm 10a on the basis of the operation of the work clutch lever.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paddy field working machine such as a walk-behind rice transplanter, and more particularly to a machine body lifting device for detecting earth pressure from a rice field and controlling the machine body height.

[0002]

2. Description of the Related Art Some conventional airframe lifting devices for walk-behind rice transplanters are provided with a hydraulic lever for switching an operation arm of a hydraulic switching valve. Since this hydraulic lever is disposed at the handle side together with the planting clutch lever and the traveling clutch lever, there is a problem that the operation when turning a paddy field vehicle on a headland is complicated.

Therefore, conventionally, a body lifting device as disclosed in Japanese Utility Model Laid-Open No. 4-133112 has been considered. As shown in FIG. 4, the airframe lifting and lowering device disclosed in this publication includes a planting clutch lever 2 connected to a planting clutch 1 and a traveling clutch lever 5 connected to a traveling clutch 3, and is also rotatable about the vehicle body. Paddy wheels are provided on the supported chain case, this chain case is connected to a hydraulic cylinder for adjusting the height of the machine body, and a hydraulic switching valve 10 communicating with this hydraulic cylinder is connected to the machine body height detection mechanism. The hydraulic pressure switching valve 10 is switched to automatically control the body height, and the body height detection mechanism is a float for detecting earth pressure on the paddy field to detect the body height. , The sensing rod 12 whose left and right boss portions are rotatably supported by a shaft 81 penetrating the mission case 32.
The tips of the protruding portions 12a protruding from the center of the left and right boss portions of 2 are inserted and connected to the connecting plate 82 fixed to the float.

The movement of the float in the vertical direction is transmitted to the sensing rod 12 as a rotation around the shaft 81, and the sensing rod 12 is transmitted to the shaft 81 as a rotation only in the vertical direction due to the support structure at both ends. It
An arm 19 is rotatably supported on the left side end of the body of the shaft 81. Further, the first plate 23 and the first plate 23 are provided between the arm 19 and the left boss portion of the sensing rod 12 supported by the shaft 81. Each second plate 26 is rotatably supported.

Further, one end of a rod 22 that movably penetrates through the elongated hole 21a of the connecting plate 21 is fixed to the first plate 23, and the other end of the rod 22 is the hydraulic switching valve. 10 operation arms 10a are connected. The hydraulic switching valve 10 communicates with the hydraulic cylinder and the hydraulic pump, and the hydraulic switching valve 1 is moved by the turning position of the operation arm 10a.
Switch 0 to raised, lowered and neutral positions.
A return spring 93 is stretched on the operation arm 10a, and the return spring 93 urges the hydraulic pressure switching valve 10 toward the lower position.

The second plate 26 has a long hole 26.
a, a first lug 26b protruding on one side surface, a second lug 26c protruding on the other side surface, and a spring hook portion 26.
d. A bolt 95 having a tightening nut is screwed into the first lug 26b so that the tip of the bolt 95 comes into contact with the side surface of the first plate 23. Then, by rotating the hydraulic pressure switching valve 10 in the raising direction, the first plate 2 regardless of the position of the second plate 26.
3 is allowed to rotate in the clockwise direction. Also, the second
Lug 26c of the second plate 26 is in contact with the sensing rod 12, and a spring 96 is stretched between the spring hooking portion 26d and the bent portion of the sensing rod 12, so that the second plate 26 and the sensing rod 12 have the spring 96. Are interlocked with each other or by contact. The sensing rod 12 and the rod 2
2, the first plate 23 and the second plate 26 form an interlocking member.

Also, on either the left or right side of the aircraft,
The operation part 1a of the planting clutch 1 and the planting clutch lever 2 are arranged, and a planting clutch system connecting means for connecting the operation part 1a and the planting clutch lever 2 is arranged. Further, a traveling clutch system coupling means for disposing the operating portion 3a and the traveling clutch lever 5 of the traveling clutch 3 on either the left or right side of the machine body and coupling the operating portion 3a and the traveling clutch lever 5 together. To place. Then, the hydraulic pressure switching valve 10
In addition, while linking the planting clutch system connecting means via a first interchange mechanism, and linking the traveling clutch system connecting means via a second interchange mechanism, on either the left or right side of the machine body, A lower hydraulic pressure adjusting unit 27 that adjusts the relationship between the planting clutch system connecting means and the first interchange mechanism, and an upward hydraulic pressure adjusting unit 29 that adjusts the relationship between the traveling clutch system connecting unit and the second interchange mechanism. I have set up.

The planting clutch system coupling means couples the first arm 14r to the planting lever rod 13 extending from the planting clutch lever 2, and connects the first arm 14r to the lug 14a formed integrally with the first arm 14r. By operating the planting clutch lever 2 through the rod 15, the planting lever rod 13, the first arm 14r, the second arm 141, the connecting plate 21, the first plate 23 and the rod 22 are used. The hydraulic switching valve 10 is connected to the operating arm 10a to switch the hydraulic switching valve 10.

The running clutch system connecting means fixes the branch plate 17 to the intermediate portion of the rod 16 extending from the running clutch lever 5, and connects the arm 19 to the tip end of the branch plate 17. Arm 19
The rod 20 is connected to the bracket 19a of the rod 16, the rod 25, the pin 25a of the plate 25, and the pin 25a.
Is connected to the operation arm 10a via a second plate 26 having a long hole 26a into which is inserted, a first plate 23, and a rod 22 so that the hydraulic switching valve 10 can be switched.

In the walk-behind rice transplanter thus constructed, when the traveling clutch lever 5 and the working clutch lever 2 are in the on position or the off position, the hydraulic pressure is switched based on the first accommodation mechanism and the second accommodation mechanism. By operating the valve 10 in the vertical direction, the machine body height is automatically controlled based on the machine body height detection mechanism. Further, when the planting clutch lever 2 is further rotated to the disengaged position, in this state, the planting clutch 1 is in the disengaged position via the planting clutch system connecting means, and the first
The flexible range is restricted so that the flexible mechanism is allowed only in the lowering direction of the machine body, and the hydraulic switching valve 10 operates in the lowering direction based on the machine body height detection mechanism. On the other hand, when the traveling clutch lever 5 is further rotated in the disengagement direction, in this state, the traveling clutch is in the disengaged position via the traveling clutch system connecting means, and the amount of accommodation in the downward direction of the second accommodation mechanism is restricted, Further, the hydraulic pressure switching valve 10 is forcibly switched to the raised position. As a result, the cylinder portion of the hydraulic cylinder is raised along with its rod, and the paddy wheel is lowered to raise the machine body.

[0011]

When the walking type rice transplanter is turned, the load of the return spring 93 for returning the operating arm 10a to the lowered position becomes maximum when the traveling clutch lever is operated to be raised. The operation load of the hydraulic pressure switching valve by the operation arm is increased, and thus the operation force of the float and the operation lever is increased. Furthermore, each part of the interlocking member that opposes the load of the return spring 93 must be strong enough to overcome the load, which causes a problem that the weight becomes heavy and the cost increases.

The present invention has been made in order to solve the above problems, and reduces the load of the lifting operation lever for switching the hydraulic switching valve to reduce the cost of the interlocking member. It is an object of the present invention to provide a body lifting device in.

[0013]

In order to achieve the above object, the body lifting device for a paddy field vehicle according to the present invention has a working section and moves up and down relatively to the paddy wheel (7). Airframe (4) and earth pressure sensor (1) suspended by the airframe (4) and moving by sensing earth pressure from the rice field
1), a hydraulic pressure switching valve (10) that is switched to a raised position, a neutral position, and a lowered position in accordance with the movement of the earth pressure sensor (11), and the hydraulic pressure from the hydraulic pressure switching valve (10), Replace the airframe (4) with the paddy wheel (7).
Hydraulic actuator that moves up and down relative to (9)
And the hydraulic switching valve (10) has a flexible mechanism (21a,
22), and a lifting operation lever (2) capable of switching and operating the hydraulic switching valve (10), the hydraulic switching valve (10) comprising:
Has an operation arm (10a) connected to the spool,
This operation arm (10a) is connected to the earth pressure sensor (11) via an interlocking member (12, 22, 23, 26) that interlocks with movement in one of the ascending position and the descending position. A swinging member (7) that is interlocked and is connected to one end of a spring (93) that is biased toward the other side, and the other end of this spring (93) is swingably supported.
1), and the swinging member (71) moves in a direction in which the urging force of the spring (93) does not change according to the operating position of the operating arm (10a) based on the lifting operation lever (2). It is characterized in that the lifting operation lever (2) and the swing member (71) are linked so as to swing.

Preferably, the raising / lowering operation lever is a work clutch lever (2) which is connected to the work clutch (1) and which is operated to interlock the hydraulic pressure switching valve (10) with respect to its upward position direction. By operating the work clutch lever (2), the operation arm (10
a) is moved in the upward position direction, and the swinging member (71) is moved in a direction in which the biasing force of the spring (93) is reduced.

[0015]

According to the above construction, when the paddy field vehicle reaches the end of the field, the operator, for example, the work clutch lever (2)
The rocking member (71) rocks by operating the lifting operation lever such as. In this state, for example, when the handle (36) is lifted and the earth pressure sensor (11) acts in a direction in which the earth pressure sensor increases, the earth pressure sensor (11) is increased.
Operates the operating arm (10a) in either one of the raised position and the lowered position via the interlocking members (12, 22, 23, 26). Further, a spring (93) for urging the operating arm (10a) in the other direction when the operating arm (10a) moves in one direction is provided between the operating arm (10a) and the swing member (71). Connected between
Operation arm (1 based on the operation of the lifting operation lever (2)
The swinging member (71) is swung in a direction in which the biasing force of the spring (93) does not change according to the movement of the operating position of 0a).

The above-mentioned reference numerals in parentheses are for comparing the drawings and do not limit the structure of the present invention.

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings.

1 to 3 are views showing an embodiment of the present invention. In FIG. 1 to FIG. 3, the same or uniform components as in FIG. . As shown in FIG. 2, the walk-behind rice transplanter P has an engine 31, a mission case 32, a frame 33, and the like in the front part of the machine body 4, and a handle 36 is extended in the rear part of the machine body 4. In addition, the seedling stand 37 is slidably supported in the left-right direction. Further, a planting rod 38 is arranged at the lower end portion of the seedling placing table 37. Further, below the frame 33, there is a rear swing fulcrum 11.
Float 11 as earth pressure sensor that can swing freely around a
Is suspended. The float 11 constitutes a body height detection mechanism that detects earth pressure on the rice field and detects the body height. Further, an output shaft 39 is provided so as to penetrate the mission case 32 on both left and right sides thereof, and further, at both ends of the output shaft 39, chain cases 6 and 6 which are swingable about the output shaft 39 are supported, and Paddy wheels 7, 7 are supported at the tips of the chain cases 6, 6.

Between the bracket 41 fixed to the engine 31 and the bumper member 42 fixed to the transmission case 32, a hydraulic cylinder 9 which is a hydraulic actuator for adjusting the height of the machine body is arranged. . The rod 9 a of the hydraulic cylinder 9 has the bracket 41.
And a movable cylinder type that is fixed to the bumper member 42, and is guided by the rod 9a to move the cylinder portion 9b.
Reciprocates up and down. Further, a balance arm 43 is swingably connected to the cylinder portion 9b about a pin 43a, and both ends of the balance arm 43 are connected to the swing chain cases 6 and 6 via rods 45 and 45, respectively. It is connected to the arms 6a, 6a fixed to the base end. In addition, the intermediate portion of the balance arm 43 and the cylinder portion 9
A horizontal control hydraulic cylinder 46 is interposed between the hydraulic cylinder 46 and b, and the cylinder 46 is controlled based on an inclination sensor 47 to move the balance arm 43 to the left and right, thereby causing the left and right paddy wheels 7 and 7 to run counter to each other. Adjust up and down.

As shown in FIG. 2, a work (planting) clutch lever 2 and a traveling clutch lever 5 which serve as a stop operation lever are arranged on a guide plate 50 provided on the handle 36 portion. Also, handle 36
Left and right side clutch levers 52L and 52R, which also serve as stop operation levers, are respectively provided on the left and right grips 36a of the
Is provided. In FIG. 2, reference numeral 53 is a main gear shift lever, and 55 is a reciprocating motion of a screw shaft arranged in the transmission case 32, which is transmitted as a swinging motion via an arm 56, and further via an arm 57. It is an oscillating rotary shaft that transmits as a left-right reciprocating motion of the seedling placing table 37.

The planting clutch lever 2 guided in the right side groove of the guide plate 50 is transmitted via a wire 60b to a right plate 59b which is rotatably supported by a lower portion of the handle 36 via a bracket. There is.
The traveling clutch lever 5 guided by the left side groove of the guide plate 50 is rotatably supported on the lower portion of the handle 36 via a bracket.
To the wire via a wire 60a. The planting lever rod 13 (see FIG. 1) extends from the right plate 59b to the front of the machine body 4 and the left plate 5b.
A rod 16 (see FIG. 3) extends from 9a in front of the machine body 4. Furthermore, the left and right side clutch levers 52L,
Wires 61L and 61R respectively extending from 52R are guided downward through the handle 36 and further forward along the frame 33. Then, while being connected to the work (planting) clutch 1, the hydraulic switching valve 1
The planting clutch lever 2 for switching 0 to the upward position direction, the traveling clutch 3 for transmitting power to the paddy wheels 7, and the traveling clutch lever 5 for switching the hydraulic pressure switching valve 10 to the downward position direction are used to move up and down. Is configured.

As shown in FIG. 1, a connecting shaft 65 extending in the lateral direction of the machine body is rotatably supported in the middle of the front and rear of the machine body 4 via a bracket 62 provided upright on the frame 33. Left and right sides of the connecting shaft 65 are rotatably supported by left and right angle members 66 and 67, respectively, which are U-shaped in a plan view, and both ends of the connecting shaft 65 are contacted with the left and right angle members 66 and 67. A U-shaped actuating link 68 that rotates when contacted is rotatably supported. That is, when the left and right angle members 66, 67 rotate and come into contact with the operation link 68, the operation link 68 pivotally supported by the connecting shaft 65 rotates. Further, one end of a connecting member 69 having a plurality of connecting holes 69a is rotatably supported on the left end of the connecting shaft 65, and one end of a spring 70 is locked in the connecting hole 69a. The other end of 70 is locked in a locking hole 71a in the upper end surface of a swinging member 71 that is rotatably supported. Further, one end of the return spring 93 is locked in the locking hole 71a, and the other end of the return spring 93 is locked in the operation arm 10a of the hydraulic pressure switching valve 10.

Further, the left end of the operating link 68 extends in a direction substantially at right angles to the left end of the operating link 68 and is connected to the connecting arm 7.
8 is fixed, and one end of a connecting rod 79 is locked to the tip of this connecting arm 78. The other end of the connecting rod 79 penetrates and is connected to the locking arm 83 fixed to the lower end of the swinging member 71. That is, the connecting end of the connecting rod 79 penetrating the locking arm 83 is a threaded portion 79a, and the nuts 84, 84 are screwed into the threaded portion 79a with the locking arm 83 sandwiched therebetween. The operation link 68 that rotates via the left and right angle members 66 and 67 or the intermediate angle member 14 by the operation of the stop operation lever, the connecting arm 78, the connecting rod 79, and the locking arm 83 are the connecting members. Make up.

The inner portion 66 of the left angle member 66
A wire 61L extending from a left side clutch lever 52L serving as a stop operating lever is connected to a, and an inner portion 67a of the right angle member 67 extends from a right side clutch lever 52R serving as a stop operating lever. The wire 61R is connected. Further, the connecting shaft 65
The intermediate angle member 14 in which the left arm 14l and the right arm 14r are integrally formed between the left angle member 66 and the right angle member 67 is rotatably supported by the. A planting lever rod 13 extending from the planting clutch lever 2 is connected to the right arm 14r of the intermediate angle member 14. A rod 72 is connected to the outer side portion 67b of the right angle member 67, and the tip of the rod 72 is connected to the operating portion 73 of the right side clutch. A rod 74 is connected to the outer side portion 66b of the left angle member 66, and the tip of the rod 74 is connected to the operating portion 75 of the left side clutch.

A lug 14a is formed integrally with the right arm 14r, and a rod 15 penetrates the lug 14a and a nut 76 screwed to the tip screw portion 15a thereof. The spring 77 is contracted. Further, the left arm 14l has the operating link 6
An operation protrusion 14b is provided so as to abut on 8 and operate this. The tip portion of the rod 15 is connected to one end of the operating portion 1a of the planting clutch 1, and the operating portion 1a
A spring 80 is stretched on the other end of the. A connecting plate 21 is connected to the tip of the left arm 141 by bolts and nuts, and the connecting plate 2
1 has a long hole 21a formed at the tip side of its rotation. The first plate 23 is fixed to the elongated hole 21a by penetrating the other end of the rod 22 connected to one end of the operation arm 10a of the hydraulic pressure switching valve 10.

On the other hand, one end of a rod 22 is fixed to the first plate 23 by penetrating the elongated hole 21a of the connecting plate 21, and the other end of the rod 22 is an operation arm of the hydraulic switching valve 10. It is connected to 10a. Then, one end of the rod 22 is connected to the long hole 2 of the connecting plate 21.
The first accommodation mechanism is configured by moving in 1a.

A pin 25a is planted in the plate 25 extending from the traveling clutch lever 5 through the raising hydraulic pressure adjusting portion 29, and the pin 25a is formed in the second plate 26 to a long length. It is movably fitted along the hole 26a, thereby constituting a second interchange mechanism.

Next, the operation will be described.

To perform planting work with the walk-behind rice transplanter P,
The traveling clutch lever 5 is operated to the on position, and the traveling clutch operating portion 3a is operated through the wire 60a extending to the left side of the machine body, the traveling rod, etc. to bring the traveling clutch into the connected state, and the planting clutch lever 2 The wire 60b extending to the right side of the machine body, the planting lever rod 13, the right arm 1 of the intermediate angle member 14
The operating portion 1a is operated via the 4r and the rod 15 to bring the planting clutch 1 into the connected state. As a result, the walk-behind rice transplanter P runs while the paddy field wheels 7 are driven, and the planting rod 38 rotates to perform planting work. At this time, the pin 2 of the plate 25 that is interlocked with the traveling clutch lever 5
5a is located in the middle of the long hole 26a of the second plate 26, and the rod 2 is provided in the middle of the long hole 21a of the connecting plate 21.
In this state, even if the rod 22 moves based on the urging force from the return spring 93 of the hydraulic pressure switching valve 10, the tip of the rod 2 has a long hole 21.
Only the a and 26a are moved, and the first plate 23 and the second plate 26 are not rotated. Therefore, the vertical movement based on the earth pressure detection of the float 11 is transmitted as the swing of the sensing rod 12, is transmitted to the second plate 26 via the spring 96, and is then transmitted via the first plate 23 and the rod 22. It is transmitted to the operation arm 10a of the hydraulic pressure switching valve 10. As a result, the hydraulic switching valve 10
Is switched to a raised position, a lowered position and a neutral position so that the body 4 has a constant height with respect to the paddy field based on the earth pressure detection of the float 11, and the hydraulic cylinder 9 is operated to move the paddy wheels 7 and 7 up and down. It moves and the height of the aircraft is automatically controlled.

Even if either or both of the traveling clutch lever 5 and the planting clutch lever 2 are operated to the disengaged position, the tip of the rod 22 and the pin 25a are provided with the elongated hole 2.
First plate 2 located in the middle of 1a and 26a
3, the hydraulic switching valve 1 does not hinder the free movement of the second plate 26 and is based on the vertical movement of the float 11 as described above.
0 is automatically controlled.

Next, a case where a walk-behind rice transplanter reaches a headland and turns the headland will be described.

When the walk-behind rice transplanter P reaches the headland, the operator operates the planting clutch lever 2. As a result, the operating arm 10a is rotated via the interchange mechanism including the planting lever rod 13, the right arm 14r, the left arm 141, the long hole 21a, and the rod 22, and the intermediate portion including the right arm 14r and the left arm 14l. The angle member 14 is rotated. Then, the operation link 68 is rotated by the rotation of the intermediate angle member 14, and then the linking member including the linking arm 78, the connecting rod 79 and the locking arm 83 is rotated, and the swinging member 71 is further swung. . In this state, for example, by lifting the handle 36, the float 11 acts in a direction in which the earth pressure sensing increases. This float 11 detects the movement of the float 1
2 and then the sensing rod 12 causes the second plate 26 and the first plate 23 to rotate. The rotation of the first plate 23 acts to move the operation arm 10a of the hydraulic pressure switching valve 10 to the raised position via the rod 22.
a has already been switched to the raised position, and the operation arm 10
Since both a and the swinging member 71 are rotated in the same direction, the return spring 93 does not change its urging force,
The handle 36 can be easily raised and operated.

Then, when the machine body 4 is raised by the above-described raising operation and the turning of the walk-behind rice transplanter P on the headland is completed, the operator returns the lifting operation lever 2. Then, the swinging member 71 returns to the position where the spring 93 has a predetermined biasing force through the linking member, and in this state, the spring 93
Returns the operation arm 10a to the lowered position and the machine body 4 descends until the earth pressure sensor 11 comes into contact with the ground and reaches the proper working position.

In the above embodiment, the swinging member 71 is
Although the rocking member 71 is rocked via the connecting rod 79 and the locking arm 83 of the linking member that is connected to the planting clutch lever 2, the rocking member 71 is provided with the planting clutch lever 2 that constitutes the lifting operation lever. You may connect directly.

In the above embodiment, the hydraulic switching valve 10 is operated by the two levers, the planting clutch lever 2 and the traveling clutch lever 5, to raise and lower the machine body 4.
It is needless to say that the present invention can be similarly applied to a device in which a dedicated hydraulic operating lever is provided and the machine body is moved up and down by the hydraulic operating lever. In this case, one hydraulic operating lever
The operating lever for raising and lowering according to the present invention is provided.

Although the above embodiment has been described with reference to a walk-behind rice transplanter, the present invention is not limited to this, and can be similarly applied to other paddy working machines such as a paddy direct watering machine.

[0037]

As described above, according to the present invention, the spring for urging the operating arm in the other direction with respect to the movement of the operating arm in one of the raised position and the lowered position swings with the operating arm. Since the rocking member is connected to a member, and the rocking member is rocked in a direction in which the biasing force of the spring does not change in accordance with the movement of the operation position of the operation arm based on the operation of the lifting operation lever, the oil pressure is switched. It is possible to reduce the load of the lifting operation lever that switches the valve, and to reduce the weight and cost of the interlocking member that moves forward when operating the lifting operation lever that rotates the operation arm.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing an embodiment of a body lifting device in a paddy field vehicle according to the present invention.

FIG. 2 is a side view showing the whole of a walk-behind rice transplanter to which the body lifting device of the above-described embodiment can be applied.

FIG. 3 is a side view showing a body raising / lowering device in the above-mentioned walk-behind rice transplanter.

FIG. 4 is an exploded perspective view showing an example of a body lifting device in a conventional paddy field vehicle.

[Explanation of symbols]

 4 Airframe 7 Paddy Wheel 9 Hydraulic Actuator (Hydraulic Cylinder) 10 Hydraulic Switching Valve 10a Operation Arm 11 Earth Pressure Sensor (Float) 12 Sensing Rod 21a Long Hole 22 Rod 23 First Plate 26 Second Plate 68 Working Link 71 Shaking Moving member 78 Connection arm 79 Connection rod 83 Locking arm 93 Return spring

Claims (2)

[Claims] 1. A body having a working unit, which moves up and down relatively to a paddy wheel, an earth pressure sensor suspended by the body, which moves by sensing earth pressure from a field surface, and the earth pressure. A hydraulic switching valve that switches between a raised position, a neutral position, and a lowered position according to the movement of the sensing body, and a hydraulic actuator that moves the machine body up and down relative to the paddy wheel based on the hydraulic pressure from the hydraulic switching valve. And a lifting operation lever connected to the hydraulic switching valve via a flexible mechanism and capable of switching the hydraulic switching valve, and a lifting device for a paddy field vehicle, wherein the hydraulic switching valve is a spool. An operation arm connected to the earth pressure sensor via an interlocking member that interlocks with the movement of the operation arm in one of the ascending position and the descending position. And the other end of the spring that is biased toward the other end, and the other end of the spring is connected to a swinging member that is swingably supported, and the operating arm based on the lifting operation lever. The lifting operation lever and the swinging member are linked so that the swinging member swings in a direction in which the urging force of the spring does not change according to the operating position of the paddy field. Aircraft lifting device for work vehicles. 2. The raising / lowering operation lever is a working clutch lever that is connected to a working clutch and that operates to interlock the hydraulic switching valve with respect to its upward position direction, and by operating the working clutch lever, The airframe lifting device for a paddy work vehicle according to claim 1, wherein the operating arm is moved in a rising position direction and the swinging member is moved in a direction in which the biasing force of the spring is reduced.