JP2002188713A - Gear shift control device for work vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To minimize a gear shift difference to a new gear shift position and to reduce a gear shift shock by an inexpensive constitution when constituting the device by combining a first gear shift device shifted by an up-down operation of a switch type gear shift operation part and a second gear shift device for shifted by a manual operation of a gear shift lever. SOLUTION: In a working vehicle provided with the first gear shift device for shifting by driving an actuator and an auxiliary gear shift device to be a second gear shift device for shifting by the manual operation of the gear shift lever, the gear shift lever is provided with a switch for raising or lowering a gear shift position of the first gear shift device and a forward/backward clutch is held in a disconnecting state during a pressing operation of the switch. When the gear shift lever is operated to other gear shift positions during the pressing operation of the switch, the first gear shift device is shifted to a speed gear stage with smallest gear shift differences of new auxiliary gear shift positions.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shift control device for a work vehicle, and more particularly to a shift control device for a work vehicle provided with a pair of switch-type operation units for instructing a current shift position of a transmission device to increase or decrease. It is about.

[0002]

2. Description of the Related Art
This type of vehicle including an agricultural tractor has a first transmission that can change a shift position by driving an actuator, a second transmission that can change a shift position by manually operating a shift lever, and power transmission. A pair of switch-type shift operating sections for raising or lowering the shift position of the first transmission, and driving the actuator in accordance with a switch signal of the shift operating section. There is known an arrangement in which the first transmission is formed so as to be switchable.

Accordingly, the gear set of the first transmission and the second
The shift position can be multi-stage by combining with a gear set of the transmission. For example, the first transmission has four shift positions of “first speed” to “fourth speed”, and the second transmission has In the case where there are three shift positions of "low speed", "medium speed", and "high speed", a total of 12 shift positions can be selected. In the conventional configuration, when the shift position of the second transmission is set to, for example, "low speed" by manual operation of the shift lever, the shift position of the first transmission is changed by the up / down operation of the switch-type shift operation unit. Can be changed in four stages from "first speed" to "fourth speed" to change the shift position within a relatively low speed range. When the vehicle speed is changed from the low speed range to the middle speed range or the high speed range, the shift position of the second transmission is changed by manual operation of the shift lever, and the first transmission is manually operated by operating the actuator. Control is performed to automatically change the speed so as to approach the previous vehicle speed.

However, in the work vehicle, the clutch may be turned on and off at an arbitrary timing according to a work state, particularly a work load, at the time of a gear shift operation. In this case, the timing may be changed by depressing a separately provided clutch pedal. Was adjusted. Therefore, particularly when the timing adjustment is required continuously, the operation is troublesome and burdens the operator.

In the case of the working vehicle, when the vehicle is not working, that is, when traveling on a road or the like, it is necessary to change the vehicle speed quickly and significantly. It is required to maintain uniformity.

Therefore, when a first transmission that is shifted by up-down operation of a switch-type shift operation unit and a second transmission that is shifted by manual operation of a shift lever are combined, a new shift position is required. In addition to minimizing the speed change difference to the minimum, the technical problem to be solved in order to reduce the speed change shock with an inexpensive configuration arises.
An object of the present invention is to solve this problem.

[0007]

SUMMARY OF THE INVENTION The present invention has been proposed to achieve the above object, and has first transmissions 41 and 43 which can change the shift position by driving an actuator.
A second transmission 44 capable of changing the shift position by manual operation of the shift lever 18; and a clutch 51 for switching power transmission on and off. The shift lever 18 has a shift position of the first transmission 41, 43. A pair of switch-type shift operation units 34 and 35 for raising or lowering the gears are provided, and the first transmissions 41 and 43 can be switched by driving the actuator according to switch signals of the shift operation units 34 and 35. When the push operation of the shift operation units 34 and 35 is continued for a certain period of time or longer in the work vehicle shift control device, the shift of the work vehicle provided with the control means 30 for holding the clutch 51 in the disengaged state is performed. A control device; and
When the shift lever 18 is changed to another shift position while the push operation of the shift operation sections 34 and 35 is continued, the shift difference between the new shift position and the previous shift position is reduced. A work vehicle provided with a control means 30 for raising or lowering the first transmissions 41, 43 when the shift position of the first transmissions 41, 43 is changed while the shift lever 18 is not changed to another shift position. Transmission control device,
And means 81 for designating a work / non-work state for the vehicle.
Alternatively, a means for detecting a work / non-work state is provided, and when the vehicle is designated to the work state or when the work state is detected, the shift lever 18 is not changed to another shift position. Control means 30 for regulating the up or down width of one transmission 41, 43 to only one step
The present invention provides a shift control device for a work vehicle including:

[0008]

An embodiment of the present invention will be described below in detail with reference to the drawings. FIGS. 1 and 2 show an agricultural tractor 10 as an example of a working vehicle, in which an engine 11 is mounted on a front portion of a vehicle body, and the rotational power of the engine 11 is appropriately changed by various transmissions in a transmission case 12 as described later. After shifting, the two rear wheels 13, 13 or the rear wheels 13,
13 and the four front wheels 14, 14. A working machine 16 such as a rotary is pulled through a link mechanism 15 at the rear of the vehicle body.

On the other hand, on the right side of the driver's seat 17, there are provided a shift lever 18 for changing the shift position of the transmission, a position lever 19 for changing the height of the working machine 16, and sub-con- verters 20, 20 for operating additional equipment. Various operation levers are arranged. In this way, by arranging various operation levers frequently used by the operator on the right side of the driver's seat 17, the operator's attention can be limited to the right side portion, and operability can be improved. .
A handle post 24 is provided in front of the driver's seat 17, and a steering handle 25 is mounted on the handle post 24. The steering handle 25
, The front wheel 14, which is a steered wheel, turns and the vehicle body turns.

A forward / reverse switching lever 26 protrudes from a side surface of the handle post 24. A forward / backward traveling of the vehicle body is selected by operating the forward / backward switching lever 26 to switch a forward / backward traveling clutch 47 to be described later. I do. Further, a meter panel 2 is provided in front of the steering handle 25.
7 and pedals such as a clutch pedal 28 and a left and right brake pedal 29 are provided below the steering handle 25. Reference numeral 30 denotes a controller serving as control means described later, and reference numeral 31 denotes a lift arm angle sensor for detecting the height of the work implement.

As shown in FIGS. 2 and 3, the speed change lever 18 protrudes upward from the inverted h-shaped lever guide 32, and has a "low speed" position inside the vehicle body and a "medium speed" outside the vehicle body. The transmission has a three-stage shift pattern of a position and a "high-speed" position on the outer rear side of the vehicle body. By rotating the shift lever 18 along the lever guide 32, the sub-transmission 44 described below operates the link mechanism. It is configured to manually switch to any of “low speed”, “medium speed”, and “high speed” via As described above, the shift pattern of the shift lever 18 is configured so as not to be shifted to the rear inside the vehicle body, and only the "low speed" position, which is less frequently used, is arranged inside the front of the vehicle body. Even when the various operation levers are arranged in a concentrated manner on the right side of the seat 17, there is no danger that the speed change lever 18 will be too close to the driver's seat 17 and erroneous operation will be performed. Operability does not deteriorate.

An up switch 34, which is a pair of switch-type shift operation sections for instructing a shift position up or down, is provided on a side surface of the grip 33 of the shift lever 18.
And a down switch 35 are provided to increase or decrease the shift pattern of the first transmission, which is a combination of a Hi-Lo transmission 41 and a main transmission 43 described later in cooperation. At a position near the lever guide 32, there is provided a push-button type high / low switch 36 for instructing the Hi-Lo transmission 41 to move up or down to a "high speed" position or a "low speed" position.

As shown in FIGS. 4 to 8, the rotational power of the engine 11 is intermittently operated by a main clutch 40 in a clutch housing, and the Hi-Lo transmission 41 in the transmission case 12 sequentially switches between forward and reverse. The transmission is transmitted to the device 42, the main transmission 43, and the auxiliary transmission 44.

The Hi-Lo transmission 41 is a transmission having a wet multi-plate Hi-Lo clutch 47 for switching between a "high speed" and a "low speed" two gear sets 45 and 46, and a controller as a control means. Hi-Lo by 30
When the clutch valve 48 is switched to the "high speed" position, the Hi-Lo clutch 47 is "engaged" on the Hi side, and power is transmitted at "high speed" via the one gear set 45.
When the Hi-Lo clutch valve 48 is switched to the "low speed" position, the Hi-Lo clutch 47 is turned "on" on the Lo side, and the other gear set 46 having a higher reduction ratio than the one gear set 45. The power is transmitted at "low speed" via the. As described above, the Hi-Lo transmission device 41 has two shift positions, and the rotational power shifted by the Hi-Lo transmission device 41 is transmitted to the forward / reverse switching device 42.

The forward / reverse switching device 42 is a transmission having a wet-type multi-plate forward / reverse clutch 51 for switching between two forward and backward gear sets 49 and 50. Is being operated by
Alternatively, the forward / reverse position sensor 52 detects whether the vehicle is being operated on the reverse side. Then, based on this detection result, a signal is sent from the controller 30 to the forward solenoid or the reverse solenoid of the forward / backward valve 54, and the forward / backward clutch 51 becomes “on” in “forward” or “reverse”, and the gear set 49, The power is transmitted to the main transmission 43 via any one of the transmissions 50. In addition, the forward / reverse switching lever 26
Is in the neutral position, the forward / reverse clutch 51 is "disengaged", the rotational power is cut off, and the rotational power is not transmitted to the main transmission 43.

The main transmission 43 is a synchromesh gear type transmission composed of four gear sets. The main transmission 43 converts the rotational power output from the forward / reverse switching device 42 from the power upper side to the fourth speed gear set 56 and the third speed gear. Set 57, 2nd gear set 58, 1
The power is transmitted to the auxiliary transmission 44 through one of the speed gear sets 59. A shifter ring having a synchromesh mechanism is provided between the drive side gears of the fourth speed gear set 56 and the third speed gear set 57, and the shifter ring is moved forward and backward by expansion and contraction of a first hydraulic cylinder 60 for a main shift as a shift actuator. The second speed gear set 58 is similarly configured to slide.
A shifter ring having a synchromesh mechanism is also provided between the drive side gears of the first gear set 59 and the first speed gear set 59, and the shifter ring is slid forward and backward by the expansion and contraction of a main shift second hydraulic cylinder 61 which is a shift actuator. I have.

The main shift "3-4" from the controller 30
When a signal is sent to the fourth-speed solenoid of the valve 62, the power is transmitted via the fourth-speed gear set 56 by the extension of the first hydraulic cylinder for main transmission 60 to become “fourth-speed” and the main transmission becomes “3-speed”. When a signal is sent to the third-speed solenoid of the “fourth-speed” valve 62, the power is transmitted via the third-speed gear set 57 due to the contraction of the first hydraulic cylinder 60 for main speed change, and “3rd-speed” is transmitted.
Speed. Further, the main transmission “1-
When a signal is sent to the second speed solenoid of the "second speed" valve 63, the power is transmitted through the second speed gear set 58 to extend to the "second speed" due to the extension of the second hydraulic cylinder 61 for main speed change. When a signal is sent to the first-speed solenoid of the “1-2-speed” valve 63, the power is transmitted via the first-speed gear set 59 due to the contraction of the second hydraulic cylinder 61 for main transmission, and the “first-speed” is transmitted. Becomes Thus, the main transmission 43
Have four gear positions from "first speed" to "fourth speed". The aforementioned Hi-Lo transmission 41 and main transmission 43
Thus, a first transmission that can change the shift position by driving the actuator is configured, and the rotational power shifted by the first transmission is transmitted to the auxiliary transmission 44 that is the second transmission.

The auxiliary transmission device 44 is a sliding mesh gear type transmission device which is switched through a link mechanism by manual operation of the transmission lever 18, and is "low speed".
It has three gear positions: a “medium speed” gear set 64, 65 and a “high speed” (directly connected) gear set 66. The rotational power shifted by the main transmission 43 is transmitted to the sub transmission 44
Is further shifted.

The rotational power shifted by the auxiliary transmission 44 is transmitted to the rear wheels 13 via a rear differential 67 and a four-wheel drive switching clutch 68
Is switched to "constant speed" or "increased speed", and transmitted to the front wheels 14 via the front differential device 69. Further, the rotational power of the engine 11 is
PTO take-off shaft 71 which is branched to a PTO system at the front stage of the vehicle, is connected / disconnected by a PTO clutch 70 and protrudes from the rear of the vehicle body.
Is transmitted to

Here, the main transmission 43 includes a main transmission "1-N-2 speed" as a means for detecting a gear combination.
A position sensor 72 and a main shift "3-N-4th speed" position sensor 73 are provided, and a sub-shift "low speed" position sensor 74 is provided in the sub-transmission device 44 as means for detecting a gear combination.
, The sub-shift "medium speed" position sensor 75, and the sub-shift "high speed"
A position sensor 76 is provided. Further, the depression operation of the clutch pedal 28 is performed by the clutch pedal sensor 7.
7, and the depression operation of the left and right brake pedals 29 is detected by a brake pedal sensor 78. Incidentally, 79 is a vehicle speed sensor for detecting the running speed of the vehicle body, 80 is an engine speed sensor, and 81 is a running / work mode switch. The detection signals of the switches 34 to 37, the forward / backward position sensor 52, and the sensors 72 to 80 are sent to the controller 30.

Thus, the Hi-Lo transmission 41 and the main transmission 43 cooperate to obtain the eight-speed transmission pattern of the first transmission. By combining the three speed change patterns, a 24-speed speed change pattern can be obtained. Then, by operating the up switch 34 or the down switch 35 provided on the grip 33 of the shift lever 18 described above, the first shift pattern in which the Hi-Lo shift device 41 and the main shift device 43 are combined in coordination from the current position. It is moved up or down, and the Hi-L
o The transmission 41 is moved up or down to the "high speed" position or the "low speed" position. And the controller 30
Determines the current shift position based on the detection signals of the switches and sensors, and displays the current shift position on the shift position indicator 82 provided on the meter panel 27.

The meter panel 27 is provided with a backup button 83 and a search button 84. When the operator presses the backup button 83, the current traveling system shift position, PTO system shift position, engine speed, etc. Are stored in the controller 30. Then, when the operator presses the search button 84 at a later date, the stored work conditions are displayed on the meter panel 27. In this way, the history of the work conditions is stored, so that the operator does not need to store, for example, the conditions worked in the previous year.

On the other hand, the main pump 8
5 and the sub-pump 86 are driven, and the hydraulic oil discharged from the main pump 85 is sent to the lift cylinder 88 for lifting and lowering the work implement through the sub-con- trol circuit 87 and to the rolling cylinder 89 for horizontal control. Part of the hydraulic oil of the main pump 85 passes through the pressure reducing valve 90 to the four-wheel drive switching clutch 68, the main transmission first hydraulic cylinder 6.
0 and the main transmission second hydraulic cylinder 61, the left and right brake cylinders 91L and 91R, the forward / reverse clutch 51, and the PTO clutch 70. The hydraulic oil discharged from the sub pump 86 is supplied to the power steering device and the main clutch 40.

Here, the grip 3 of the shift lever 18
When the up switch 34 or the down switch 35 provided in 3 is pressed, as described above,
In response to a command signal from the controller 30, the first shift pattern in which the Hi-Lo transmission 41 and the main transmission 43 are combined in cooperation is moved up or down from the current position. For example, when the shift lever 18 is shifted to the low-speed position, the sub-transmission 44 as the second transmission is in the “low-speed” position, and the first shift pattern is switched by operating the up switch 34 or the down switch 35. In other words, the shift speed is changed within a range from “1st speed” to “8th speed”. On the other hand, for example, when the shift lever 18 is shifted to the high-speed position, the sub-transmission 44 is in the “high-speed” position, and the operation of the up switch 34 or the down switch 35 changes the shift speed to “17”. From "24
The speed is changed within the range of "gear".

Next, when the traveling / work mode switch 81 is set to the work mode, or
A control procedure when the shift lever 18 is operated to another shift position while the up switch 34 or the down switch 35 is being pressed when the work state is detected by the detection signal of the sensor. , FIG. 9
This will be described according to the flowchart of FIG. First, the controller 30 monitors the pressing operation of the up switch 34 and the down switch 35 (steps 1 and 2). When the up switch 34 has been pressed for a predetermined time or more, a flag Up is set (step 3), and when the down switch 35 is pressed for a certain time or more, a flag Dn is set (step 4). When either the up switch 34 or the down switch 35 is pressed for a predetermined time or more, the controller 30 outputs a command signal to the forward / reverse valve 54 to
7 is set to a cutting state, that is, a neutral position (step 5).

Subsequently, the operation of the shift lever 18 is monitored (step 6). When the shift lever 18 is operated to increase the speed while the up switch 34 or the down switch 35 is being pressed, the auxiliary transmission 4 as the second transmission is operated.
In this case, the first transmission is shifted to the lowest shift speed at the new sub-shift position (step 8). For example, the Hi-Lo transmission 41 is “high” and the main transmission 4
3 is "3rd speed" and the auxiliary transmission 44 is in the "low speed" state, that is, in the state in which the shift speed is "6th speed",
If the shift lever 18 is operated from the "low speed" position to the "medium speed" position during the push operation of the downshift switch 4 or the down switch 35, the controller 30 switches to the "medium speed" position and at the same time, the controller 30 The Hi-Lo valve 48, the main transmission 3-4 speed valve 62, and the main transmission 1-2 speed valve 63 are controlled to set the Hi-Lo transmission 41 to "low" and the main transmission 43 to "1st". That is, the gear is shifted to "9th" which is the lowest shift speed of the new subtransmission "middle speed". Further, for example, when the shift lever 18 is operated from the "medium speed" position to the "high speed" position in the state where the shift speed is "12th speed", the sub-transmission 44 switches to the "high speed" position, and at the same time, Hi
-Lo transmission 41 is set to "low" and main transmission 43 is set to "1".
"Gear", that is, the gear is shifted to "17th gear" which is the lowest gear of the new auxiliary transmission "high speed".

On the other hand, when the shift lever 18 is operated to the deceleration side during the pushing operation of the up switch 34 or the down switch 35, the first transmission is shifted to the highest shift stage at the new sub shift position ( Step 9). For example, H
The i-Lo transmission 41 is “low” and the main transmission 43 is “3”.
Speed, and the auxiliary transmission 44 is in the "high speed" state, that is, in the state in which the shift speed is "21", the shift lever 18 is moved from the "high speed" position while the up switch 34 or the down switch 35 is being pressed. When operated to the "medium speed" position, the sub-transmission 44 switches to the "medium speed" position, and at the same time, the controller 30 sets the Hi-Lo valve 48, the main shift 3-4 speed valve 62 and the main shift 1-2. By controlling the speed valve 63,
The Hi-Lo transmission 41 is shifted to "high" and the main transmission 43 is shifted to "fourth speed", that is, the gear is shifted to "16th speed" which is the highest speed of the new subtransmission "medium speed". Further, for example, when the shift lever 18 is operated from the "high speed" position to the "low speed" position in a state where the shift speed is "19", the sub-transmission 44 is switched to the "low speed" position, and at the same time, Hi- L
o The transmission 41 is shifted to "high" and the main transmission 43 is shifted to "fourth", that is, the gear is shifted to "8", which is the highest speed of the new auxiliary transmission "low".

On the other hand, when the up switch 34 or the down switch 35 is pressed, the shift lever 1 is pressed.
If the operation No. 8 is not performed, the above-described flag is determined (step 7), and if the flag is Up, the first speed change pattern is increased by one step in the current sub speed change position (step 1)
0). If the flag is Dn, the first shift pattern is reduced by one step in the current auxiliary transmission (step 11). When the pressing operation of the up switch 34 or the down switch 35 is released (step 12), the shift of the first transmission is stopped and the forward / reverse clutch 5 is stopped.
1 to the original state (forward or reverse) (step 1
3).

As described above, when the speed change lever 18 is operated to increase the speed while the up switch 34 or the down switch 35 is being pressed, the speed is shifted to the lowest speed position within the new sub speed change position. The shift difference between the previous shift position and the new shift position is minimized. On the other hand, when the shift lever 18 is operated to the deceleration side during the pressing operation of the up switch 34 or the down switch 35, the gear is shifted to the highest speed position in the new sub-shift position, so that the previous shift position is The shift difference from the new shift position is minimized.
Thus, the shift shock when the clutch is engaged can be suppressed as much as possible. The sub-transmission 44 is a sliding mesh gear type, but the transmission lever 1
By temporarily disengaging the hydraulic multi-plate type forward / reverse clutch 51 in conjunction with the operation 8, it is possible to perform a shift operation with less shift shock while being a non-synchromesh mesh.

As described above, when shifting the first transmission and the second transmission, the Hi-Lo clutch 47 and the forward / reverse clutch 51 are turned on and off.
As shown in (1), the boosting characteristics of the clutch are different between the work mode and the traveling mode. When the traveling / work mode switch 81 is set to the work mode,
As shown in FIG. 7A, the Hi-Lo clutch 47 is used.
, The forward / reverse clutch 51 maintains the full pressure state. This takes into account the influence of the traction load of the work implement 16 and the like, and switches the Hi-Lo clutch 47 while keeping the forward-reverse clutch 51 connected without being disconnected. On the other hand, when the traveling / work mode switch 81 is set to the traveling mode, when the Hi-Lo clutch 47 is switched as shown in FIG.
Once the forward / reverse clutch 51 is disengaged, the pressure is increased relatively slowly after the Hi-Lo clutch 47 is connected. This is because if the Hi-Lo clutch 47 is switched while the forward / reverse clutch 51 is in the full pressure state during traveling, a shift shock occurs and the traveling feeling deteriorates.

The present invention can be variously modified without departing from the spirit of the present invention, and it is natural that the present invention extends to the modified ones.

[0032]

As described in detail in the above embodiment, the present invention according to claim 1 is a shift control in which a shift lever is provided with a switch for instructing the shift position of the first transmission to go up or down. In the device, when the pushing operation of the switch continues for a predetermined time or more, the clutch is kept in the off state. Therefore, the vehicle can be driven with the clutch engaged at an arbitrary timing according to the work state.

Further, according to the present invention, when the shift lever is operated to another shift position while the switch is being pressed, the shift difference between the new shift position and the previous shift position is reduced. Since the shift position of the first transmission is changed so as to be small, in addition to the effect of the invention described in claim 1, during normal operation, the fluctuation range of the vehicle speed is suppressed to prevent sudden acceleration and sudden deceleration. can do.

Further, according to a third aspect of the present invention, the shift lever is moved to another shift position while the switch is being pressed, when the vehicle is designated to be in the working state or when the working state is detected. When the first transmission is not operated, the up or down width of the first transmission is limited to only one step, so that in addition to the effects of the invention described in claim 1 or 2, the shift can be performed at any timing during work. In addition, since the fluctuation of the vehicle speed due to the switch operation is suppressed to one stage, the uniform work is not hindered.

[Brief description of the drawings]

 The figure shows an embodiment of the present invention.

FIG. 1 is a side view of a tractor.

FIG. 2 is a partially cutaway plan view of a driver's seat.

FIG. 3 is a perspective view of a transmission lever.

FIG. 4 is a block diagram of a shift control system.

FIG. 5 is a diagram showing a power transmission path.

FIG. 6 is a list showing shift patterns of the transmission.

FIG. 7 is a front view of the meter panel.

FIG. 8 is a hydraulic circuit diagram.

FIG. 9 is a flowchart illustrating a procedure of a shift control.

FIG. 10 (a) is a timing chart of pressure increase of a clutch in a work mode. (B) A pressure rise timing chart of the clutch in the traveling mode.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Tractor 18 Shift lever 30 Controller 34 Up switch 35 Down switch 41 Hi-Lo transmission device 43 Main transmission device 44 Secondary transmission device 51 Forward / reverse clutch

Continuation of the front page (72) Inventor Hideaki Saeki 1 Tochi-cho, Tobe-cho, Iyo-gun, Ehime Pref.

Claims (3)

[Claims] A first transmission which can change a shift position by driving an actuator;
Transmission 44 capable of changing the shift position by manual operation of
And a clutch 51 for turning on and off the power transmission. The shift lever 18 is provided with a pair of switch-type shift operating sections 34 and 35 for instructing the shift positions of the first transmissions 41 and 43 to increase or decrease. Operation units 34, 35
In the shift control device for a work vehicle in which the actuators are driven in accordance with the switch signal to switch between the first transmissions 41 and 43, the shift operation unit 34,
A shift control device for a work vehicle, comprising: a control unit (30) for holding the clutch (51) in a disengaged state when the pressing operation of (35) is continued for a predetermined time or more. 2. When the shift lever 18 is changed to another shift position while the push operation of the shift operation sections 34 and 35 is continued, the shift difference between the new shift position and the previous shift position is small. Thus, when the shift position of the first transmissions 41 and 43 is changed, and the shift lever 18 is not changed to another shift position, the control means 30 that raises or lowers the first transmissions 41 and 43. The shift control device for a work vehicle according to claim 1, further comprising: 3. The vehicle is provided with a means 81 for designating a working / non-working state or a means for detecting a working / non-working state, and when the vehicle is designated as a working state or when the working state is detected. When the shift lever 18 is not changed to another shift position, the first transmission 41,
The shift control device for a work vehicle according to claim 1 or 2, further comprising a control unit (30) for restricting an up or down width of the (43) to only one step.