JPH0455455Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Industrial Application Field] The present invention relates to a lifting control device for rice field working machines such as rice transplanters, fertilizers, and seeding machines. [Problems to be solved by the prior art and the invention] In general, in this type of paddy field working machine, the attitude of the machine body with respect to the rice field is not changed due to changes in the unevenness of the tiller on which the running wheels run. By automatically switching the elevation control valve based on the detection of unevenness of the tiller, the running wheels are moved up and down relative to the machine body, thereby automatically controlling the elevation. By the way, with this machine, it has become possible to maintain the necessary attitude of the aircraft by limiting the automatic switching of the elevation control valve when traveling on the road, turning the aircraft, moving backward, or replenishing seedlings. There is. However, conventionally, the operating tool used to limit the automatic switching of the valve is biased toward the automatic switching position in response to the operating force for automatically switching the elevation control valve. As a result, even if the operating tool is operated to the valve switching regulation position, the operating force for automatic switching will always act to force it to move away from the regulation position, making it unstable. Therefore, the operation tool has the disadvantage that it is easily switched by a slight wave of the hand or a shock such as vibration, which poses a problem. [Means for solving the problem] In view of the above-mentioned circumstances, the present invention was devised for the purpose of providing a lifting control device for a paddy field working machine that can eliminate these drawbacks. In paddy field work switching, which is performed by automatic switching of an elevation control valve that links the vertical movement of the machine body with the vertical movement of a sensing float, operating tool means is operated to limit the automatic switching of the elevation control valve. , the operating position of the operating tool means is changed by swinging the first cam arm connected to the elevation control valve side in a direction opposite to the direction in which the operating force for automatically switching the elevation control valve acts on the first cam arm. By operating the operating tool means to the valve switching restriction position, the locking body provided on one cam arm is applied to the locking receiver provided on the other cam arm with the said operating force. It is characterized in that it is configured to abut and lock in the direction of action of the valve, thereby preventing the operating tool means from coming off from the valve switching restriction position due to the operating force. With this configuration, the present invention makes it possible to reliably prevent the operating tool means from being switched inadvertently due to the actuation force for automatically switching the elevation control valve. It is something. [Example] Next, an example of the present invention will be described based on the drawings. In the drawing, 1 is a walking type rice transplanter, and the rice transplanter 1 is equipped with an engine 2 in the front.
A seedling platform 3 with a lower front and rear height is provided at the rear, and unit planting seedlings are scraped from the seedling platform 3 and planted on the rice field by the planting operation of a planting claw 4 timed with the movement of the aircraft. Everything is the same as before. Reference numeral 5 denotes a running wheel, and the running wheel 5 is supported by a wheel 5a at the tip of a second chain case 6 constituting a bent chain case. The proximal end portion is pivotally supported by the distal end portion of the first chain case 7 so as to be swingable (flexible). The first chain case 7 is pivotably supported on the upper part of the transmission case 8 about a support shaft 7a as a fulcrum. The running wheels 5 are adapted to travel and rotate as a result of the driving force from the engine being transmitted through the transmission case 8, the first chain case 7, and the second chain case 6. Further, it is connected via a link 14a to a telescopic cylinder 14 for lifting and lowering wheels, which will be described later, and a fulcrum 23a accompanying its telescopic operation.
Due to the swinging of the swinging arm 23 using the swinging arm 23 as a fulcrum, both the chain cases 6 and 7 change into a bent swinging shape, and as a result, the running wheels 5 follow a trajectory as shown in FIG. It is designed to move up and down. On the other hand, 9 is a sensing float (center float)
The sensing float 9 has a support shaft 9a at the rear.
The front portion is supported on the body side by a bending link mechanism 10. Furthermore, the lower end of a link rod 12 is connected to the sensing float 9, and the upper end of this link rod 12 is constantly urged downward by the ammunition X to the lower end of the operating link 15. Further, the operating link 15 is provided with a long hole-shaped flexible portion 15a, and a pin 12b that loosely fits through the flexible portion 15a is inserted into the valve shaft 13a of the elevation control valve 13.
It protrudes from an actuating plate 16 that is integrally provided with the actuating plate 16.
When the sensing float 9 swings up and down due to changes in ground pressure from the field surface due to changes in the unevenness of the tiller, the operating link 15 moves up and down together with the link rod 12, causing the operating plate 16 to rise. (When the plowing platform becomes deep and the machine sinks), it is rotated in the direction of arrow C, and when descending (the machine rises), it is rotated in the opposite direction. When the machine rotates in the direction of arrow C, the machine moves upward, and when it rotates in the opposite direction of arrow C, the machine moves downward.This reduces the telescopic cylinder 14 and lowers the traveling wheels 5 relative to the machine. It is now possible to perform vertical movement control. Further, on the actuating plate 16, connecting links 17 and 18 are provided on the upper and lower sides with the valve shaft 13a sandwiched therebetween, and pins 17b and 18 are connected to elongated flexible portions 17a and 18a.
8b. The upper second connecting link 17 is interlocked with the tip of a second hydraulic wire 37, which will be described later, and the lower first connecting link 18 is connected with the tip of a first hydraulic wire 36, which will also be described later. Furthermore, between the pin 18b and the outer receiver 37a side of the second hydraulic wire 37 of the bracket 1a (the bracket 1a is integrally fixed to the main body side) where the outer receivers 36a, 37a of both wires 36, 37 are provided. , actuation plate 1
A bullet Z is interposed to urge the ball 6 in the opposite direction C. On the other hand, 24 is a shift clutch lever, and the shift clutch lever 24 is operated to its corresponding shift position (in the embodiment, two forward gears F1, F2, neutral N, and reverse R positions) to connect the gear. Rod 25
The shifter shaft 26, which is connected to the connecting rod 25 via the link arm 26a, is moved in and out of the transmission case 8, thereby causing the shift clutch mechanism (not shown) to move as described above. This gear shift clutch lever 24 is provided with a protruding pin 24a, and this pin 24a is connected to the driving handle 2 by a pin shaft 27b.
It is opened in the movable plate 27 which is pivotably mounted on the zero side, and the reverse side end thereof passes through an arc-shaped elongated hole 27a which is notched in the shape of a substantially circular arc. When switching between the neutral N position and the forward F1 and F2 positions as shown above,
The pin 24a moves within the range of the elongated hole 27a, and the movable plate 27 does not move, but when operated from the neutral position N to the reverse position R, the pin 24a comes into contact with the end of the elongated hole 27a. The movable body 27 is oscillatedly displaced in the direction of arrow A in FIG.
The connecting rod 28, whose lower end is connected to the connecting rod 28, is pulled and moved in the direction of arrow B. The fulcrum 27b of the movable plate 27 is eccentric with respect to the arcuate fulcrum of the elongated hole 27a, so that when the transmission clutch lever 24 is operated to the reverse position, the pin 24a is placed at the end of the elongated hole. Notch 27b in
When the transmission clutch lever 24 is operated from the reverse R to the neutral N position, the movable plate 27 is swung back to its original position by pressing the engagement portion. Note that 24b is a guide for the speed change clutch lever 24. On the other hand, 29 is an operation case provided at the center of the upper part of the left and right driving handles 20, and the operation case 29
A support shaft 29a provided between the left and right side plates of the left side has a lever that can be switched between ``enter'', ``off'', and ``fix'' by linear operation from the hand side to the front side along the lever guide 29a. The boss portion 30a of the traveling clutch lever 30 can be moved to the right side, and it can be turned into, cut, fixed, and raised by linear operation from the hand side to the front side along the lever guide 29b. A boss portion 31a of a planting clutch lever 31 that can switch levers is rotatably connected. These levers 30 and 31 correspond to the operating tools of the present invention, and their "fixed" position corresponds to the "valve switching restriction position" of the present invention, as will be described later. First cam arms 32, 3 are provided on the outside of 30a, 31a.
3 are each pivotally connected. Also, both levers 3
0 and 31 include connecting arms 30b and 31b, as well as first cam arms 32 and 33 and second cam arm 3, which will be described later.
Lever pins 30c and 31c related to 8 and 39 are provided, respectively. One end of a traveling clutch wire 34 is connected to the distal end of the traveling side connecting arm 30b, and one end of a planting clutch wire 35 is connected to the distal end of the planting side connecting arm 31b. By operating the lever guide 29a from the "off" position to the "on" position (the most forward operating position), the traveling clutch wire 34 is pulled, thereby turning the traveling clutch (not shown) into the ON state. On the other hand, by similarly operating the planting clutch lever 31 from the "off" position to the "on" position in the lever guide 29b, the planting clutch wire 35 is loosened, which causes the planting clutch wire 35 to be loosened. The planting clutch
It is set to be in the ON state. Further, a pin 32c provided at one end of the first cam arm 32 on the traveling side is attached to a bullet Y (the relationship between the biasing forces of the bullet Y and the bullets X and Z described above is X>Z). , and set so that X<Z+Y) is interlocked and connected to the base end of the first hydraulic wire 36 via an interposed buffer mechanism 19, and Pin 33 provided at one end
A base end portion of a second hydraulic wire 37 is interlocked and connected to c, and furthermore, cam surfaces 32a and 33a corresponding to lever pins 30c and 31c are connected to one end portion of the first cam arms 32 and 33, and cam surfaces 32a and 33a on the traveling side first cam arm 3
2 is formed with a cam surface 32d corresponding to a pin 42c of a third cam arm 42, which will be described later, and a pin (corresponding to the locking body of the present invention) is formed at the other end of both first cam arms 32, 33. ) 32b, 33b are provided in a protruding manner. Further, second cam arms 38 and 39 are provided on the left and right side plates of the operation case 29, respectively, and the first cam arms 32 and
33, and is pivotally connected by pin shafts 38a and 39a so as to be freely swingable. This second cam arm 3
8 and 39 are both first fired by the ammunition 40.
As shown in Fig. 4, the second cam arm 38 on the traveling side is biased in the direction of arrow D when the traveling clutch lever 30 is operated to the "off" position and the "fixed" position. , cam surfaces 38b and 38c on which the lever pin 30c abuts and locks, and a cam surface 38 corresponding to a pin 42b of a third cam arm 42, which will be described later.
d, and a cam surface 38e (corresponding to the locking receiver of the present invention) that locks the pin 32b beyond the corner portion 38f, as will be described later. In addition, the second cam arm 39 on the planting side has cam surfaces 39b, 39 on which the lever pin 31c comes into contact and locks when the planting clutch lever 31 is operated to the "cut" position, "fixed" position, and "up" position, respectively.
c, 39d, and a cam surface 39e (also corresponding to the locking receiver of the present invention) that locks when the pin 33b exceeds the corner portion 39f as described later.
is formed. The lever pins 30c, 31c press the cam surfaces and swing the second cam arms 38, 39 against the elastic force 40 to maintain the levers 30, 31 in their corresponding positions. It is accomplished by moving in a state of crossing mountains. Incidentally, when both levers 30 and 31 are operated to the "enter" position, they are held at that position by a fulcrum crossing action. Furthermore, the first cam arm 3
2 and 33, when the levers 30 and 31 are operated to the "off" position, the lever pins 30c and 31c come into contact with the cam surfaces 32a and 33a, and the lever pins 30c and 31c are operated toward the front side of the "off" position. Therefore, it is designed to swing and displace integrally with the lever pins 30c and 31c. Furthermore, due to this lever switching operation, the pins 32b and 33b of the first cam arm are positioned more forward than the corner portions 38f and 39f when the levers 30 and 31 are in the "off" position as described later. , in the "fixed" position,
As mentioned above, the anti-D resistance of the second cam arms 38, 39 against the bullet 40 caused by operating the lever to this position
The corner part 3 is aligned with the timing of the direction swing.
The first cam arms 32, 33 are held in a locked position by abutting against and engaging with cam surfaces 38e, 39e extending beyond 8f, 39f. In addition, 41 is a cam arm 32,
33, 38, and 39 are stoppers protruding from the case body 29 to prevent them from swinging beyond a predetermined position. When both the travel clutch lever 30 and the planting clutch lever 31 are operated between the "off" and "on" positions, the lever pins 30c, 31c are moved to the second cam arms 38, 39 as shown in FIG. The pins 18b and 17b on both the first connecting link 18 and second connecting link 17 sides are brought into contact with the cam surfaces 38b and 39b and then moved away from the cam surfaces 38b and 39b. , 17a, and is in an automatic control state. In this state, when the sensing float 9 moves up and down with respect to the machine body due to the unevenness of the tiller, the actuating plate 16 swings by the vertically moving pin 12b, the machine body sinks, and the actuating plate 16 moves to the fifth position. When the aircraft swings in the direction C in the figure, the elevation control valve 13 is switched to the aircraft lifting side, and when the aircraft lifts and the operating plate 16 swings in the opposite direction C, the elevation control valve 13 is switched to the aircraft lowering side. In this way, it is possible to bring the aircraft into an "automatic control" state in which the aircraft is automatically controlled to maintain a substantially constant posture relative to the rice field. On the other hand, when the planting clutch lever 31 is operated to the "fixed" position, the planting clutch lever 31
In this case, the lever pin 31c comes into contact with the cam surface 39c of the second cam arm 39 and is held in this position, but the movement of the lever pin 31c at this time also causes the first cam arm 33 to swing in the same direction. The second hydraulic wire 37 is pulled by approximately the amount of play between the pin 17b and the front end of the flexible portion 17a, thereby rotating the actuating plate 16 in the opposite direction of arrow C, that is, moving the valve 13 toward the lowering side of the fuselage. This is designed to discourage switching. Therefore, when the traveling clutch lever 30 is in the "on" or "off" position and the planting clutch lever 31 is operated to the "fixed" position, only the lifting operation of the machine body is automatically performed and the lowering operation is fixed. The state is "raised automatically lowered fixed". Furthermore, when the planting clutch lever 31 is operated beyond the above-mentioned "fixed" position to the "up" position, the planting clutch lever 31 is moved to the lever pin 3.
1c is brought into contact with and locked to the cam surface 39d of the second cam arm 39, and is held in this position.
is also oscillated in the same direction, thereby pulling the second hydraulic wire 37 and moving the second connecting link 17 rearward, forcibly rotating the actuating plate 16 in the direction of arrow C to open the valve 13. When the machine is switched to the up side, and the traveling clutch lever 30 is in the "on" and "off" positions and the planting clutch lever 31 is operated to the "up" position,
The aircraft enters the "manual lift" state, where the aircraft rises by manual lever operation. On the other hand, when the travel clutch lever 30 is operated from the "off" position to the "fixed" position, the travel clutch lever 30 is moved so that the lever pin 30c is connected to the second cam arm 3.
The lever pin 30c abuts and locks the first cam arm 38c on the cam surface 38c of the first cam arm 30, and is held in this position.Due to the lever movement at this time, the lever pin 30c displaces the first cam arm 32 in the direction of the arrow E. As a result, the first hydraulic wire 36
is pulled so as to compress the ammunition Y, and the pin 18b comes into contact with the front end of the flexible portion 18a, causing the actuating plate 16 to rotate in the direction of arrow C, that is, the valve 13 moves toward the body-raising side. Switching to is restricted. Therefore, when the planting clutch lever 31 is in the "on" or "off" position and the traveling clutch lever 30 is operated to the "fixed" position, only the lowering operation of the machine body is automatically performed and the raising side is fixed. If both levers 30 and 31 are operated to the "fixed" position, rotation of the operating plate 16 to either side is restrained, and the aircraft In this way, the levers 30 and 31 are in a "fixed" state with no vertical movement.
Control switching is now possible. In this way, a valve switching mechanism for switching the elevation control valve 13 in this embodiment is constructed. Furthermore, when the driving clutch lever 30 is operated to the "fixed" position while the planting clutch lever 31 is operated to the "up" position as described above,
The planting clutch lever 31 is adapted to be automatically displaced to the "fixed" position. In other words, when the planting clutch lever 31 is operated to the "up" position,
As mentioned above, the lever pin 31c is connected to the second cam arm 3.
The pin 33b of the first connecting link 33 is in an unlocked state as it is separated from the cam surface 39e of the second cam arm, and the first connecting link 33 is held in contact with the cam surface 39d of the second cam arm. The side pin 18b is in contact with the front end of the flexible portion 18a. In this state, the traveling clutch lever 30 is operated from the "off" position to the "fixed" position, and the first hydraulic wire 36 is pulled rearward while compressing the ammunition Y.
6 forcibly rotated in the opposite direction of arrow C.
3 to the neutral state, the second hydraulic wire 37
is pulled forward while receiving a buffering effect from the bomb Y, and this forward pulling force causes the first link arm 33 on the planting side to move the lever pin 31c in a direction opposite to the arrow E.
As a result, the lever pin 31c swings the second cam arm 39 against the bullet 40 and crosses over the mountain between the cam surfaces 39d and 39c, and the pin 33b touches the cam surface 39e. The planting clutch lever 31 is automatically displaced to the abutting position, that is, the "fixed" position. Further, the third cam arm 42 is swingably supported on the side plate of the operation case 29 via a support shaft 42a, and one end of the third cam arm 42 is provided with the aforementioned shift clutch lever 24. arrow B when moving backwards.
The upper end of the connecting rod 28 that moves in the direction is the pin 42b.
is further connected by a third cam arm 4.
2, on the traveling clutch lever 30 side, the cam pin 42c is related to the cam surface 32d formed on the one end 32a side of the first cam arm 32, and the cam surface 38d is formed on the upper end of the second cam arm 38. cam pins 42d are formed respectively. Then, when the third cam arm 42 moves in the direction of arrow B due to the movement of the connecting rod 28 in the direction of arrow B due to the operation of the transmission clutch lever 24 to the reverse position, the first cam arm 32 moves to the cam surface 32d of the cam pin 42c. When the travel clutch lever 30 is pressed to the "fixed" position as described above, it swings in the same manner as when the travel clutch lever 30 is operated to the "fixed" position, thereby pulling the first hydraulic wire 36 and moving the valve 13 toward the body-raising side. While the second cam arm 38 is in a state where the switching of the cam pin 4 is checked, the second cam arm 38 is
2d, the lever pin 30c is oscillated in the opposite direction of the arrow D against the bullet 40, and the lever pin 30c is released from the cam surface 38c, and the traveling clutch lever 30 is brought to the "fixed" position. Automatic displacement is now possible. Then, when the planting clutch lever 31 is operated to the "raise" position and the second hydraulic wire 37 is pulled in this switching check state on the aircraft raising side, the first hydraulic wire 36 is stretched due to the compression of the ammunition Y, and the actuating plate is 16 is rotated in the direction of arrow C, and the elevation control valve 13 is switched to the aircraft raising side, and when the aircraft is moving backwards, the valve switching to the aircraft raising side is restrained, and this is only possible when the lever is operated manually. The restraints have been released and the aircraft is now able to raise itself. Furthermore, during this reverse operation, the direction in which the cam pin 42d of the cam surface 38d is pressed is set so as to be applied in the direction of the connecting rod 28 beyond the fulcrum of the support shaft 42a, so that the reverse movement position of the transmission clutch lever 24 is It is designed to be able to maintain positioning. In the embodiment of the present invention constructed as described above, when the traveling clutch lever 30 and the planting clutch lever 31 are operated to the "on" and "off" positions, the elevation control valve 13 is operated so that the actuating plate 16 moves in both directions. It is in an automatic control state that allows it to swing. Therefore, by the vertical movement of the flexible part 15a of the sensing float 9 that detects the unevenness of the tiller, the elevation control valve 13 is switched to the raising side or the lowering side of the machine body, and the machine body is automatically raised and lowered. As a result, the attitude of the machine relative to the rice field can be maintained substantially constant regardless of the unevenness of the tiller. In this way, automatic control of the aircraft attitude is performed by automatic valve switching based on the vertical sensing motion of the sensing float 9.
And, when the planting clutch lever 31 is running on the road, when the aircraft is turning, when replenishing seedlings, or when moving backward, at least one of the levers 30, 31
is operated to the "fixed" position to limit switching of the lift control valve 13. In this case, the sensing float 9 is not locked, so
The sensing float 9 moves up and down based on the unevenness of the tiller, and this causes an actuation force to swing the actuation plate 16, and this actuation force causes the first cam arms 32, 33 to move in the opposite direction. It will be pulled in the direction of arrow E. However, the first cam arms 32 and 33 come into contact and lock with the locking pins 32b and 33b facing the cam surfaces 38e and 39e of the second cam arms 38 and 39 in the same direction as the direction of the operating force. . However, the second cam arms 38 and 39 are always urged in the direction of the arrow D by the ammunition 40, that is, in the direction of the reverse arrow E, and the second cam arms 38 and 39 are urged in the direction of the arrow D, that is, in the direction of the reverse arrow E, and are urged in the direction of the reverse arrow against the ammunition 40 based on the switching of the levers 30 and 31. By swinging in the D direction, the lever 30,
Therefore, the actuation force for the second cam arms 38, 39 to perform the automatic valve switching is the one that controls the lever switching and positions and holds the second cam arms 38, 39. It will work towards this. As a result, the lever 30,
31 is no longer in an unstable state due to the actuation force required for automatic valve switching, and switches to an automatic control state when a slight hand shake or aircraft vibration occurs as in the past. I never get tired. As a result, the levers 30 and 31 are securely held in the "fixed" position, and the levers are no longer held in that position, resulting in an inadvertent lever switching.

[Table] It goes without saying that the present invention is not limited to the above-mentioned embodiments, and the locking body and the locking receiving portion can be provided on the cam arm in a reverse relationship, and the specific structure thereof may be There is no particular limitation on the means as long as one locking body abuts and locks the other locking body in the direction in which the operating force is applied. [Operation and Effect] In summary, since the present invention is constructed as described above, when the operating tool means operated to limit the automatic switching of the elevation control valve is operated to the valve switching restriction position, the second An operating force for automatically switching the elevation control valve is applied to the cam arm via the first cam arm, but the direction of the operating force is determined by the second cam arm, which positions and holds the operating tool means. Match the direction. As a result, the operating force no longer acts on the second cam arm in the direction of releasing the holding of the operating tool means as in the conventional case, but rather acts on the side of positively holding the operating tool means. Therefore, the operating tool means can prevent the valve switching from being accidentally switched due to a light shaking of the hand or the shock of machine vibration, etc., and the valve can be switched simply by switching the operating tool means. Switching can be performed from the regulated position, resulting in superior safety and accurate operation.

[Brief explanation of drawings]

The drawings show an embodiment of the elevating and lowering control device for the working part of the rice paddy work machine according to the present invention, in which Fig. 1 is an overall side view of the walking rice transplanter with the bonnet removed, and Fig. 2 is an overall side view of the walking rice transplanter with the bonnet removed. 3 is a side view of the elevation control cylinder section, FIG. 4 is a plan view of the elevation control cylinder section, FIG. 5 is a side view of the elevation control mechanism, FIG. 6 is an explanatory diagram of the operation of the main transmission clutch lever, and FIG. Figure 7 is a connection diagram of the main transmission clutch lever, Figures 8 J and K are front views and sectional views of the first cam arm on the traveling side, and Figures 9 J and K.
10 is a front view and a sectional view of the second cam arm, and FIGS. 10 J and K are a front view and a sectional view of the first cam arm on the planting side.
Figures 11 J and K are a front view and a cross-sectional view of the second cam arm, Figures 12 J and K are a front view and a cross-sectional view of the third cam arm, and Figure 13 is a front view and a cross-sectional view of the operating handle. 14
The figure is a side view with a part of the front cut away, Figure 15 is a plan sectional view of the main part of the front, Figure 16 is a bottom sectional view of the main part of the front, Figure 17 is a rear view of the rice transplanter, and Figure 18 is The figure is an explanatory diagram showing the movement of the cam arm when the traveling clutch lever is operated, Figure 19 is an explanatory diagram showing the movement of the cam arm when switching to reverse mode, and Figure 20 is the planting clutch lever. FIG. 21 is an explanatory view showing the operation of the cam arm when the cam arm is operated, and FIG. 21 is an explanatory view showing the operation position of the traveling clutch lever and the planting clutch lever. In the figure, 1 is a traveling aircraft body, 5 is a traveling wheel, 9 is a sensing float, 13 is a lift control valve, 16 is an operating plate, 17 and 18 are connecting links, 24 is a main transmission clutch lever, 30 is a traveling clutch lever, 31 32 and 33 are first cam arms, 36 and 37 are hydraulic wires, 38 and 39 are second cam arms, and 42 is a third cam arm.

Claims (1)

[Scope of utility model registration request] In a paddy field working machine in which the vertical movement of the machine body is performed by automatic switching of a lifting control valve linked to the vertical movement of a sensing float, operating tool means operated to limit the automatic switching of the lifting control valve is provided. , the operating position of the operating tool means is changed by swinging the first cam arm connected to the elevation control valve side in a direction opposite to the direction in which the operating force for automatically switching the elevation control valve acts on the first cam arm. By operating the operating tool means to the valve switching restriction position, the locking body provided on one cam arm is applied to the locking receiver provided on the other cam arm with the said operating force. 1. An elevation control device for a paddy field working machine, characterized in that the device is configured to abut and lock in the direction of action of the operating tool to prevent the operating tool means from being removed from the valve switching restriction position due to the operating force.