JPH0714125Y2 - Steering operation structure of work vehicle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a pair of hydraulically operated side clutches for turning on and off power to a pair of left and right traveling devices, and a hydraulic pressure for braking one of the traveling devices. The present invention relates to a steering operation structure for a work vehicle including an operation side brake.

[Conventional technology]

In the combine, which is one of the above-mentioned work vehicles,
An example of the steering operation structure is disclosed in JP-A-63-13866.

In this structure, a pair of left and right crawler type traveling devices are provided with a pair of side gears, and one side gear is slid by a hydraulic cylinder to separate from the transmission side gear, so that transmission to one traveling device is performed. Turn off to make a gentle turn (side clutch disengaged). Then, the side gear is further slid by the hydraulic cylinder, and the multi-plate side brake is pushed and operated by the side gear, so that one traveling device is braked to make a pivotal turn.

[Problems to be solved by the device]

With this structure, the side clutch is maintained in the disengaged state by maintaining the piston of the hydraulic cylinder projecting for about half stroke, and the pressing force by the piston is changed while the piston is projected for almost the full stroke. , The side brake is configured to be changed and operated. As a result, the above-described two operations are performed by one hydraulic cylinder, so that hydraulic control of the hydraulic cylinder is relatively difficult.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a steering operation structure for a work vehicle equipped with a hydraulically operated side clutch and a side brake so that the side clutch can be disengaged and the side brake can be operated to the braking side accurately. I am trying.

[Means for Solving the Problems]

The feature of the present invention resides in the following structure in the steering operation structure of the work vehicle as described above.

Equipped with a pair of hydraulically operated side clutches for turning on and off the power to a pair of left and right traveling devices, and a hydraulically operated side brake for braking one of the traveling devices. A valve, a control valve that changes the operating pressure of the side brake, and an operation lever that is artificially operated. When the operation lever is operated from the neutral stop position to the first setting position, the switching valve is operated. When one of the side clutches is operated to disengage and the operating lever is operated beyond the first set position to the second set position, the operating lever and the switching lever are switched so that the operating stroke of the operating lever is absorbed. Even if the operating lever is operated from the neutral stop position to the first setting position by interlockingly connecting with the valve through the elastic body and the first linking mechanism, the operation stroke of the operating lever is absorbed and the control valve is operated. Is not, the second operating lever beyond the first setting position
The operation lever and the control valve are set so that the control valve is operated to the braking side of the side brake when operated to the set position side. Through a mechanical interchange and a second linkage mechanism that absorbs the operation stroke below. The movable range of the elastic body is set smaller than the operation stroke of the first linkage mechanism.

[Action]

(I) In the conventional structure, both the side clutch and the side brake are controlled by one operating system called a hydraulic cylinder and a control valve for the hydraulic cylinder. Then, the side clutch operating system and the side brake operating system are set separately, such as the side clutch operated by the switching valve and the side brake operated by the control valve toward the braking side. .

As a result, since the side clutch and the side brake are operated independently by the switching valve and the control valve, the side clutch and the side brake are operated more than one operation system (hydraulic cylinder). The control range of each brake is widened, and the hydraulic control of the side clutches and side brakes is facilitated.

(Ii) As described above, when the configuration of the present invention is provided with the switching valve for the side clutch and the control valve for the side brake, the operation lever (39) is operated from the neutral stop position to the first setting position. Then, for example, as shown in FIG. 6, the switching valve (33) is operated via the elastic body (44) and the first linkage mechanism (45), and the one side clutch (25R), (25L). Is turned off. On the other hand, the operation of the operating lever (39) is absorbed by the mechanical interchanges (A ₁ ) and (A ₂ ) and is not transmitted to the control valve (36).
8) remains cut.

In this way, the operating lever (39) is moved within the range (between the neutral stop position and the first set position) until the mechanical interchanges (A ₁ ) and (A ₂ ) with respect to the control valve (36) disappear. By operating, the side clutches (25R) and (25L) can be turned on and off while the side brake (28) remains turned off.

Next, from the state in which the operating lever was operated to the first setting position (the state in which mechanical interchange (A ₁ ) and (A ₂ ) disappeared), further operate the operating lever (39) to the second setting position side. As you go
Since the mechanical accommodations (A ₁ ) and (A ₂ ) have disappeared,
The control valve (36) is operated by the linkage mechanism (53) and the side brake (28) is operated toward the braking side.

When the operation lever (39) is operated from the first setting position to the second setting position in this way, the first linkage mechanism (45) tends to operate the switching valve (33) beyond the operation range. The operating stroke of the operating lever (39) for the elastic body (4
The changeover valve (33) will not be forced to operate beyond the operating range by being absorbed in 4).

(Iii) In the case where the side clutch switching valve and the side brake control valve are separately provided, when the operation lever is started to be operated from the neutral stop position to the first setting position, the side clutch switching valve is first. Must be operated.

However, especially in cold regions and when temperatures drop,
The viscosity of the lubricating grease in the switching valve may decrease, and the spool of the switching valve may become difficult to move. In such a state, the elastic body connecting the operation lever and the switching valve loses the operation resistance of the spool, and even if the operation lever is started from the neutral stop position, the elastic body is displaced and the switching valve is operated. If it is not operated, the side clutch will not be disengaged.

Therefore, as in the present invention, the displaceable range (L ₂ ) of the elastic body (44) is larger than the operation stroke (L ₁ ) of the first linkage mechanism (45).
If is set to a small value, for example, as shown in FIG. 5, if the operating lever is operated until the elastic body (44) reaches the limit of the displaceable range (L ₂ ), the elastic body (44) cannot be displaced any more. On the other hand, the operation lever (first linkage mechanism (45)) is still in a state in which it can be operated further. Therefore, if the operating lever is operated beyond the displaceable range (L ₂ ) of the elastic body (44), the switching valve is forcibly operated via the elastic body (44) that cannot be displaced.

[Effect of device]

As described above, by separately setting the operation system of the side clutch and the operation system of the side brake, the control range of each of the side clutch and the side brake is widened, and the hydraulic control is facilitated. We were able to improve the operating accuracy of the clutch and side brakes.

Further, a structure in which the switching valve and the control valve for the side clutch and the side brake can be operated without trouble by one operating lever through the elastic body and the mechanical interchange can be obtained, and the functionality can be improved. did it.

Further, even if the side clutch switching valve is in a difficult state to move, the switching lever can be forcibly operated by the operating lever to prevent the side clutch from being disengaged. Became.

〔Example〕

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

FIG. 16 shows the structure in the transmission case (8) of the traveling system of the combine, which is one of the work vehicles, in which the power from the engine (not shown) has a belt transmission mechanism (not shown) equipped with a tension clutch. ) Is transmitted to the input pulley (2) of the hydrostatic stepless transmission (1), and the power from the output shaft (3) of the hydrostatic stepless transmission (1) is transferred to the first transmission shaft. It is transmitted from (4) through the one-way clutch (5) and the output pulley (7) to the reaper (6) shown in FIG.

The power from the first transmission shaft (4) is applied to the first gear (9) and the second gear (9).
The second transmission shaft (11) is transmitted through the gear (10) and the second
A first high speed gear (12) and a first low speed gear (13) are fitted onto the transmission shaft (11) so as to be rotatable relative to each other, and a shift gear (14)
Has a spline structure and is slidably fitted on the outside.
On the other hand, the second high speed gear (16) and the second low speed gear (17) fixed to the third transmission shaft (15) are the first high speed gear (12).
And the first low speed gear (13), and the middle speed gear (18) is fixed to the third transmission shaft (15). With the above structure, the shift gear (14) is slid to engage with the first high speed gear (12), the medium speed gear (18) and the first low speed gear (13), whereby the power is divided into three stages of high, medium and low. It is possible to change gears, and this power is the third that meshes with the medium speed gear (18).
It is transmitted to the gear (19).

A right side gear (21R) and a left side gear (21L) are fitted to the support shaft (20) supporting the third gear (19) so as to be rotatable relative to each other, and the input gears of the left and right axles (22R) and (22L) ( twenty three
R) and (23L) are always engaged with the right and left side gears (21R) and (21L). As a result, the right or left side gear (21R), (21L) is slidingly operated with respect to the third gear (19) to engage and separate from each other, and the sprocket (24a) of the crawler type traveling device (24) shown in FIG. ), The power transmission is turned on and off, and the side clutch (25L) is connected between the third gear (19) and the right and left side gears (21R), (21L).
R) and (25L) are configured.

Next, a structure for braking one of the axles (22R) and (22L) will be described. As shown in FIG. 16, the support shaft (20)
A right fourth gear (26R) and a left fourth gear (26L) are rotatably supported relative to each other, and a pair of fifth gears (29) fixed to the fourth transmission shaft (27) is a right fourth gear. (26R) and the left fourth gear (26L) are engaged. Fourth transmission shaft (27)
A multi-plate hydraulically operated side brake (28) is provided at one end of the right side gear (21R) or left side gear (2R).
1L) is separated from the third gear (19) and the right fourth gear (26
R) or the left fourth gear (26L) in an engaged state, the side brake (28) is operated to the braking side to brake one of the axles (22R) and (22L).

Next, a structure for reversing one of the axles (22R) and (22L) will be described. As shown in FIG. 16, the third transmission shaft (1
The sixth gear (62) that meshes with the second high speed gear (16) of 5) is fitted onto the fourth transmission shaft (27) so as to be rotatable relative to the sixth gear (62) and the fourth transmission shaft (27). Hydraulic clutch between and (30)
Is provided. As a result, the right side gear (21R)
Alternatively, the left side gear (21L) is replaced by the right fourth gear (2L) as described above.
6R) or the left fourth gear (26L) is engaged, and the hydraulic clutch (30) is engaged and operated, the second high speed gear (16)
The power from the vehicle is reduced to 1/2 in the reverse direction and the axle (22R),
It is transmitted to (22L).

Next, a hydraulic oil supply structure for the hydraulic cylinders (31R), (31L), the side brakes (28), and the hydraulic clutch (30) for sliding the right and left side gears (21R), (21L) will be described. As shown in FIG. 6, the pump (32)
Is supplied to the hydraulic cylinders (31R), (31L) for the right and left side gears (21R), (21L) via the first switching valve (33) (corresponding to the switching valve), and the hydraulic cylinder ( The oil passages (34) from the side surfaces of 31R) and (31L) are connected to the second brake control valve (35) for the side brake (28) and the hydraulic clutch (30), and the side brake (34) is connected to the oil passage (34). 28) and the variable relief valve (36) (corresponding to a control valve) for the hydraulic clutch (30) are connected. The relief valve (61) keeps the pressure of the entire hydraulic circuit at a safe allowable pressure.

Next, the operation structure of the first switching valve (33), the second switching valve (35) and the variable relief valve (36) will be described. As shown in FIG. 7 and FIG. 8, the front and rear axis (P ₂ ) of the frame (38) swingably supported around the left and right axis (P ₁ ) of the body control section (not shown). The operation lever (39) is swingably supported around the operation lever (39) so that the operation lever (39) can be swung back and forth and left and right. The first arm (40) is fixed to the operation lever (39), and the first arm (40) and the first switching valve (33) are linked.

As shown in FIGS. 1, 7, and 9, the operation plate (43) and the arm (41a) are provided in front of and behind the support shaft (41) which is rotatable around the front-rear axis (P ₃ ) of the mission case (8). Is fixed to the arm (41
a) is connected to the spool (not shown) of the first switching valve (33), and the operation plate (43) is connected to the actuator (42). A long hole (43a) is provided in the operation plate (43), and a push-pull wire (45) (corresponding to a first linkage mechanism) is connected to the first arm (40) of the operation lever (39) to form a push-pull wire. The pin (45a) of (45) is engaged with the long hole (43a). A spiral spring (44) (corresponding to an elastic body) is attached so as to sandwich both the pin (45a) and the pin (43b) of the operation plate (43).

With the above structure, as shown in FIGS. 1, 2, and 7, when the operating lever (39) is operated around the longitudinal axis (P ₂ ) to, for example, the left side clutch disengaged position (corresponding to the first set position), the push lever is pushed. The pull wire (45) is pulled and the helical spring (4
The first switching valve (33) is operated to the left side clutch disengaged side via the 4) and the operation plate (43). As described above, by operating the operation lever (39) to the right or left side clutch disengagement position (corresponding to the first setting position), hydraulic oil is supplied to one of the hydraulic cylinders (31R) and (31L). Piston (31
RP) and (31LP) project downward, and the side gear arm (46
R) and (46L) are rocked to operate the right side gear (21R)
Or the left side gear (21L) is separated from the third gear (19),
It engages with the 4th right gear (26R) or the 4th left gear (26L).
This is a slow turning state in which one of the side clutches (25R) and (25L) is disengaged.

In the state shown in FIG. 2, the spool of the first switching valve (33) reaches the stroke end and cannot move any further. However, as will be described later, even if the push-pull wire (45) is further pulled by operating the operation lever (39) to the left braking position (corresponding to the second set position) and the left reverse rotation position, FIG. Also, as shown in FIG. 4, the spiral spring (44) is opened, and the operation stroke of the operation lever (39) is only absorbed, so that the operation of the operation lever (39) is not hindered.

As shown in FIG. 6, the right and left side gears (21R) and (21L) are moved to the right and left by the sequence valve (47) provided in the oil passage (34) from the hydraulic cylinders (31R) and (31L). The pressure required to completely engage the fourth gears (26R) and (26L) is ensured in the hydraulic cylinders (31R) and (31L). The actuator (42) automatically operates the first switching valve (33) when the machine automatically travels along the planted culm, and is free when operating the operation lever (39) as described above. It is in a state of moving to.

Next, a linkage mechanism of the operation lever (39), the second switching valve (35) and the variable relief valve (36) will be described. As shown in FIGS. 7 and 8, the first swing arm (50) and the second swing arm (50)
The swing arm (51) is swingably supported around the front-rear axis (P ₂ ) independently of the operation lever (39).
The pin (49) fixed to the first arm (40) of the operation lever (39) is inserted between the first and second swing arms (50) and (51) and fixed to the frame body (38). Round bar (64) is also the first
And the second swing arms (50) and (51). The spring (52) causes the first and second swing arms (5
The release wire (53) is installed over 0) and (51).
An inner wire (53a) (corresponding to a second linkage mechanism) is attached to the first swing arm (50), and an outer wire (53b) is attached to the second swing arm (51).

As shown in FIGS. 10, 11, and 12, the second switching valve (35) and the variable relief valve (36) are arranged in parallel, and the spool (35a) of the second switching valve (35) and the variable relief valve (36). ), (36a), the first operation arm (48) is fixed to the inside of the support shaft (54) rotatable about the shaft center (P ₄ ), and the second operation arm is provided outside the support shaft (54). The operation arm (55) is fixed, and the inner wire (53a) of the release wire (53) is connected to the spring (5
It is erected and connected to the second operation arm (55) via 6).

The state shown in FIGS. 10 and 12 is a state in which the operation lever (39) is operated to the neutral stop position (N), and the pin (55a) of the second operation arm (55) and the spring (56) are During
Also, there is a mechanical interchange (A ₁ ) and (A ₂ ) between the pin (53c) of the inner wire (53a) and the spring (56). The second operation arm (55) and the first operation arm (48) are urged clockwise by the spiral spring (63) in FIG. 12 and counterclockwise in FIG.

Move the operating lever (39) shown in FIG. 7 around the front-rear axis (P ₂ ) to, for example, the left side clutch disengaged position (corresponding to the first set position).
When operated to the side, the first swing arm (50) is moved by the pin (49) of the first arm (40) with the second swing arm (51) abutting against the round bar (64) and stopped. Is oscillated rightward on the paper surface, and the inner wire (53a) is pulled.
On the contrary, move the operating lever (39) to the right side clutch disengaged position (1st
If it is operated toward the setting position) side, the first swing arm (5
(2) is stopped by the round bar (64), the second swing arm (51) is swing-operated to the left side of the drawing by the pin (49), and even in this state, the second swing arm (51) moves against the outer wire (53b). The inner wire (53a) is pulled.

However, the right side clutch disengaged position (corresponding to the first set position) and the left side clutch disengaged position (corresponding to the first set position)
Even if the operating lever (39) is operated within the range, the interchanges (A ₁ ) and (A ₂ ) in FIG. 12 disappear (see FIG. 13), and within this range, the first arm (40) ), Only the first switching valve (33) is operated, and only the on / off operation of the right and left side clutches (25R), (25L) as described above is performed.

Next, when the operating lever (39) is operated beyond the right and left side clutch disengaged positions (corresponding to the first setting position) to the right or left braking position (corresponding to the second setting position), the inner Due to the pulling action of the wire (53a), the state shown in FIG.
As shown in the state of FIG. 4, the first operation arm (48) is rocked to move the first contact portion (48a) of the first operation arm (48).
As a result, the spool (36a) of the variable relief valve (36) is pushed toward the throttle opening closing side. In this range, the spool (35a) of the second switching valve (35) is not pushed by the first operating arm (48), and the second switching valve (35) is provided with the detent mechanism (57) and the spring (58). ), It is held on the hydraulic oil supply side to the side brake (28) (the right protruding side of the spool (35a) in FIGS. 10 and 14). Therefore, as shown in FIG. 7, the operation lever (39) is operated from the right and left side clutch disengaged positions (corresponding to the first setting position) to the right or left braking position (corresponding to the second setting position) side. As you go, gradually the side brakes (28)
The braking force of can be increased.

This state is a pivotal turning state in which one traveling device (24) is braked. In this case, the operation plate (43) and the push-pull wire (45) of the first switching valve (33) are shown in FIG. The state is as shown. That is, the push-pull wire (45) can open the spiral spring (44) while the operation plate (43) is stopped at the right or left side clutch disengagement position (first setting position) shown in FIG. Then, it is operated to the right or left braking position (corresponding to the second set position).

Next, when the operating lever (39) is operated from the right or left braking position (corresponding to the second set position) to the right or left reverse position,
The inner wire (53a) is further pulled and the 14th
As shown in the state of FIG. 15 to the state of FIG. 15, the variable relief valve (3) is provided by the first contact portion (48a) of the first operation arm (48).
While pushing the spool (36a) of 6) further,
The spool (35a) of the second switching valve (35) is pushed by the second contact portion (48b) of the operation arm (48), and the second switching valve (35) supplies the hydraulic oil to the hydraulic clutch (30). When one of the traveling devices (24) is decelerated to 1/2, the traveling device (24) is reversely driven.

In this case, the operation plate (43) and the push-pull wire (45) of the first switching valve (33) will be in the state as shown in FIG. That is, with the operation plate (43) stopped at the left side clutch disengaged position (corresponding to the first set position) shown in FIG. 2, the push-pull wire (45) further opens the spiral spring (44). In this way, it is operated to the left reverse position.

Next, the state where the spool of the first switching valve (33) is hard to move will be described. For example, even if the operating lever (39) is operated to the left side clutch disengaged position (corresponding to the first setting position) or the left braking position (corresponding to the second setting position), the first switching valve (3
If the spool in 3) does not move, only the spiral spring (44) opens as shown in FIG. 5, and the operation plate (43) and the first switching valve (33) remain in the neutral stop position (N). It will be in a state like.

In this case, the displaceable range (L ₂ ) in which the spiral spring (44) can be opened is the long hole (43a) as shown in FIG.
The range is equivalent to. On the other hand, the operation stroke (L ₁ ) of the push-pull wire (45) is the helical spring (44).
Since it is larger than the displaceable range (L ₂ ) of the push-pull wire (45), if the operating lever (39) is operated to the left reverse position as shown in FIG.
Contacts the end of the elongated hole (43a), and the operation plate (43) and the first switching valve (33) are forcibly operated to the left side clutch disengaged position (corresponding to the first set position).

As shown in FIGS. 7 and 6, a support shaft (59) for swingably supporting the operation lever (39) and the frame body (38) around the left and right axial center (P ₁ ) and a cutting section (6). ) Is mechanically interlocked with the third switching valve (37) for the hydraulic cylinder (60) for lifting and lowering, and the operating lever (39) is swingably operated around the left and right axis (P ₁ ). Thereby, the reaper (6) can be moved up and down.

As shown in FIGS. 7 and 8, the supporting portion (38) of the frame (38) is
A contact sensor (68) for detecting that the operation lever (39) is operated to the neutral stop position (N) is fixed to a), and the plate material is triangular with the pin (49) of the first arm (40). The contact piece (69) bent over is fixed. This allows
The operating lever (39) is operated during automatic operation by the actuator (42) to move the contact (68) of the contact sensor (68).
When the contact piece (69) separates from a), this is detected by the contact sensor (68) and the operation signal to the actuator (42) is interrupted.

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

[Brief description of drawings]

The drawings show an embodiment of a steering operation structure of a work vehicle according to the present invention. FIG. 1 is a front view of an operation system of a first switching valve and a hydraulic cylinder, and FIG. 2 is an operation lever from a state shown in FIG. Is a front view of the operation plate and the push-pull wire corresponding to the state in which the operation lever is operated to the left side clutch disengagement position. FIG. FIG. 4 is a front view of the push-pull wire, FIG. 4 is a front view of the operation plate and the push-pull wire corresponding to a state in which the operation lever is operated to the left reverse position from the state shown in FIG. 1, and FIG. FIG. 6 is a front view corresponding to a state where the operation lever is operated while the operation plate is difficult to move, and FIG. 6 is a hydraulic circuit diagram showing a connection state of the first, second and third switching valves, the hydraulic cylinder, the variable relief valve, etc. in the combine, Figure 7 shows the operating lever A front view, FIG. 8 is a side view near the operation lever, FIG. 9 is a longitudinal side view showing the operation system of the first switching valve, and FIG. 10 is a second switching valve, a variable relief valve and its operation system. Fig. 7 is a vertical sectional front view corresponding to a state in which the operating lever of Fig. 7 is operated to the neutral stop position, Fig. 11 is a vertical sectional side view showing the operating system of the second switching valve and the variable relief valve, and Fig. 12 is The operation system of the second switching valve and the variable relief valve is shown, and the front view (rear view with respect to FIG. 10) corresponding to the state where the operation lever shown in FIG. 7 is operated to the neutral stop position, FIG. 7 is a front view of the operation system of the second switching valve and the variable relief valve corresponding to the case where the operation lever shown in FIG. 7 is operated to the right or left side clutch disengagement position, and FIG. 14 is the front view of the operation lever shown in FIG. The second switching valve, the variable relief valve and the corresponding one when operated to the left braking position Fig. 15 is a vertical cross-sectional front view of the operation system, Fig. 15 is a vertical cross-sectional front view of the second switching valve, the variable relief valve and the operation system corresponding to when the operation lever shown in Fig. 7 is operated to the right or left reverse rotation position. FIG. 17 is a vertical sectional front view of the mission case of the combine, and FIG. 17 is a side view of the first half of the combine. (24) …… Traveling device, (25R), (25L) …… Side clutch, (28) …… Side brake, (33) …… Switching valve,
(36) …… Control valve, (39) …… Operating lever, (44) ……
Elastic body, (45) …… first linkage mechanism, (53) …… second linkage mechanism, (L ₁ ) …… operation stroke of the first linkage mechanism,
(L ₂ ) …… Displaceable range of elastic body, (N) …… Neutral stop position of operating lever.

Claims (1)

[Scope of utility model registration request] 1. A pair of hydraulically operated side clutches (25R) for turning on and off power to a pair of left and right traveling devices (24),
(25L) and a hydraulically operated side brake (28) for braking one of the traveling devices (24), and a switching valve (33) for switching on / off of the side clutches (25R), (25L). ), A control valve (36) for changing the operating pressure of the side brake (28), and an operation lever (39) that is artificially operated, and the operation lever (39) has a neutral stop position ( When operated from N) to the first set position, the switching valve (33) is operated to disengage one of the side clutches (25R) and (25L), and the operation lever (39) is operated. The operation lever (39) and the switching valve (33) are elastic so that the operation stroke of the operation lever (39) is absorbed when the operation lever is operated beyond the first setting position toward the second setting position. The body (44) and the first linkage mechanism (45) are interlockingly connected to each other, and the operation lever (39) is From standing stop position (N) is operated in the first setting position, the control valve operation stroke is absorbed in the operating lever (39) (36) is not operated,
The operation lever (39) moves beyond the first set position to the second position.
When the control valve (36) is operated to the set position side, the operation lever (39) and the control valve (36) are set to the setting or less so that the control valve (36) is operated to the braking side of the side brake (28). The mechanical strokes (A ₁ ), (A ₂ ) for absorbing the operation stroke, and the second linkage mechanism (53) are interlocked and linked, and the operation stroke (L ₁ ) of the first linkage mechanism (45) is used. Also, the steering operation structure of the work vehicle in which the displaceable range (L ₂ ) of the elastic body (44) is set to be small.