JP2009156386A - Traveling motion transmission device of working vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To rather make the effective use of a clutch engaging rotary motion different from clutch engaging and disengaging operations that perform doubly engaging braking by a clutch pedal in operating a clutch button provided on a grip of a sub transmission shift lever. <P>SOLUTION: There is provided the working vehicle which is provided with transmission shift gears which perform multistage shift transmission by means of the engagement and disengagement of a hydraulic clutches 25 to 28 and further enables braking by the double engagement of the transmission shift gears in a stepping operation on a clutch pedal. In the working vehicle, a controller is provided which interlocks a given clutch among the hydraulic clutches 25 to 28 to be disengaged without allowing the transmission shift gears to perform the double engagement when pressing the clutch button provided on the sub-transmission shift lever 74. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a traveling transmission device for a work vehicle such as an agricultural tractor, in which a double-engaged state in which a plurality of speed-changing gears that perform multi-gear gear shifting are simultaneously meshed with each other and traveling by a follow-up transmission when the clutch pedal is disengaged. The present invention relates to a traveling transmission device for a work vehicle that can smoothly perform sub-transmission gear shifting while preventing the shifting.

  In an agricultural tractor, conventionally, when the clutch pedal is operated, the forward / reverse clutch and the high / low speed switching clutch are operated to the “disengagement” side to make the main transmission portion lightly double-engaged so that the engine power is not transmitted to the rear axle. (For example, patent document 1).

In addition, there is a configuration in which a clutch button is provided on the auxiliary transmission lever and the clutch is disengaged when the clutch button is pressed so that a gear shift operation can be performed without operating the clutch pedal (Patent Document 2).
JP 2007-320357 A JP 2002-13561 A

However, when shifting by operating the sub-shift lever, the shift meshing condition of the sub-shift is poor, and it is necessary to perform the meshing operation while lightly connecting the forward / reverse clutch.
According to the present invention, when the clutch button provided in the grip portion of the auxiliary transmission lever is operated, the clutch engagement is effectively used, unlike the clutch engagement / disengagement of the double engagement braking by the clutch pedal.

  The invention according to claim 1 is provided with a transmission gear (6-9) that performs multi-stage shifting by turning on and off of the hydraulic clutch (25-28), and at the time of depressing operation of the clutch pedal (45), the transmission gear (6-9). ) Of the work vehicle configured to be able to be braked by double biting, the double gear of the transmission gear (6-9) is engaged when the clutch button (73) provided on the sub-shift lever (74) is pressed. It is set as the structure of the driving | running | working transmission apparatus of the working vehicle which provided the controller (44) which interlock | cooperates the predetermined clutch among the hydraulic clutches (25-28) without carrying out.

  The traveling transmission of the work vehicle such as a tractor is transmitted by being meshed in series with the parallel transmission gears (6 to 9) and the other transmission gears in the front-rear direction, and the selection is made by connecting hydraulic clutches arranged respectively. However, when the clutch pedal is depressed, the other transmission gear (6-9) other than that engaged is engaged and the hydraulic clutch (25-28) of this transmission gear is engaged and operated. Put it in a state. Since the double-geared transmission gears (6 to 9) are locked and do not rotate, transmission to and after the transmission gears can be stopped to be in a braking state. Further, when the clutch button (73) provided on the grip of the auxiliary transmission lever (74) is operated to disengage the clutch, the predetermined hydraulic clutch is merely interlocked with the disengagement side, not the double engagement state. By allowing the attachment, and effectively utilizing this attachment, the gears are smoothly engaged when the auxiliary transmission gear is switched.

  According to the second aspect of the present invention, when the work vehicle detects a traveling state and shifts the sub-transmission device to the deceleration side, the hydraulic clutch is turned on when the detected speed of the work vehicle is decelerated to a speed near the shift position. It is set as the structure of the driving | running | working transmission apparatus of the working vehicle of Claim 1 which provided the controller (44) interlock | cooperated to an entrance side.

  Accordingly, when the clutch button (73) is released after the clutch button (73) is pressed and the sub-transmission device is operated to the deceleration side, the vehicle speed is detected and the vehicle speed is decelerated to the vehicle speed in the vicinity of the speed change position to be decelerated. If it is determined that the hydraulic clutch has been engaged, the hydraulic clutch is engaged. Therefore, it is possible to prevent the clutch from being engaged immediately after the clutch button (73) is released to enter a sudden deceleration state.

  According to the first aspect of the present invention, it is possible to perform braking by double-engaging the speed change gears (6 to 9) when the vehicle is traveling because it can be performed only when the vehicle speed is in a low speed range below a certain level. The sudden stop of the vehicle body at the time can be eliminated, the shock can be reduced, and safe braking can be performed without difficulty. On the other hand, the clutch button (73) provided on the grip of the auxiliary transmission lever (74) is operated. Thus, when the clutch is disengaged, the auxiliary transmission gear can be smoothly switched by effectively using the attachment.

  According to the second aspect of the present invention, although the auxiliary transmission can be switched in the running state by the clutch button (73), the auxiliary transmission can be smoothly and smoothly reduced with little shock, and the clutch button. As soon as (73) is released, it is possible to prevent the clutch from being engaged and suddenly decelerating.

  Based on the illustrated example, the tractor TR has a front wheel 1 steered by a steering handle 70 and a rear wheel 2, and is installed in a transmission case 71, an axle housing 72, and the like by an engine 3 mounted on the front. It is configured in a riding four-wheel drive traveling form that travels by being transmitted through a transmission mechanism. And the work machine R is connected to the rear part so that raising and lowering is possible.

  The transmission mechanism includes a forward / reverse switching device having forward and reverse gears 4, 5 from the engine 3, and four-speed gears such as a first speed gear 6, a second speed gear 7, a third speed gear 8, and a fourth speed gear 9. The first main transmission device, the second main transmission device having high and low two-stage transmission gears such as the Hi-speed gear 10 and the Lo-speed gear 11, and the three-speed transmissions such as the auxiliary transmission gears 12, 13, 15 and the like. The rear wheel 2 is transmitted in conjunction with the rear differential mechanism 16 through a sub-transmission device having a gear and a neutral gear 14 and switching the sub-shift to high speed H, medium speed M, low speed L, and neutral N.

Further, the auxiliary transmission device transmits the front wheel 1 in conjunction with a four-wheel drive switching device capable of switching between the two-wheel drive / four-wheel drive gear 17 and the double speed four-wheel drive gear 18 and a front differential gear 19.
The engine 3 is configured to transmit a PTO shaft 22 via a PTO transmission clutch 21 through a four-stage PTO transmission 21 via a PTO transmission clutch 20.

  If the arrangement along the transmission direction of the forward / reverse switching device, the first main transmission device, the second main transmission device, the sub-transmission device, and the like is set as the series direction, the forward gear 4 in each of these devices is The reverse gear 5 is configured in a parallel arrangement (see FIG. 5). The forward gear 4 and the reverse gear 5 of this forward / reverse switching device have front and reverse hydraulic clutches 23 and 24 in the form of multiple friction plates, and the front and rear hydraulic clutches 23 and 24 are hydraulic clutches by hydraulic pressure from a hydraulic circuit. By pressing the pack, the forward hydraulic clutch 23 or the reverse hydraulic clutch 24 can be engaged and disconnected to rotate the forward gear 4 or the reverse gear 5. These forward and reverse hydraulic clutches 23 and 24 are selectively operated to switch between forward transmission and reverse transmission.

  The first main transmission has the first-speed hydraulic clutch 25 to the fourth-speed hydraulic clutch 28 of the friction multi-plate type as described above in each of the first-speed gear 6 to the fourth-speed gear 9, and similarly the hydraulic pressure The first-speed hydraulic clutch 25 to the fourth-speed hydraulic clutch 28 are turned on and off by the clutch pack, and the first-speed gear 6, the second-speed gear 7, the third-speed gear 8, or the fourth-speed gear 9 is selected and interlocked. It is configured in an arrangement form. Similarly, the second main transmission also has a Hi hydraulic clutch 30 of the same form in the Hi speed gear 10 and a Lo hydraulic clutch 29 in the Lo speed gear 11 and is turned on and off by a hydraulic clutch pack. It is configured to do.

  Each auxiliary transmission gear 12, 13, 15 of the auxiliary transmission has clutch rings 31, 32 in the form of a dog clutch, and is configured to move forward and backward by a shifter operation.

  In FIG. 3, the hydraulic circuit for operating each device is provided with a tank port T for receiving lubricating oil and a hydraulic pump P, and a first speed of the first main transmission having the power steering hydraulic circuit 35 and the hydraulic clutch pack. A hydraulic clutch 25 to a four-speed hydraulic clutch 28, a Lo hydraulic clutch 29 of a second main transmission, a Hi hydraulic clutch 30, a forward hydraulic clutch 23 of a forward switching device, a reverse hydraulic clutch 24, and the like are provided. , 18 hydraulic clutch packs, PTO clutch 20 hydraulic clutch packs, and the like.

Further, solenoid valves 36 to 42 operated by electromagnetic output from the controller 44 are arranged in the hydraulic circuit of each hydraulic clutch pack.
On the input side of the controller 44, there is provided a clutch pedal switch 45 that is turned on and off by depressing the clutch pedal, and the solenoid valve 40 of the forward / reverse switching circuit is operated to disconnect the front and rear hydraulic clutches 23, 24. In this embodiment, the forward and reverse hydraulic clutches 23 and 24 are also used as the main clutch.

  Further, a clutch pedal stroke sensor 46 for detecting the amount of depression of the clutch pedal 45, an accelerator sensor 47 for detecting the amount of depression of an accelerator pedal (not shown), an oil temperature sensor 48 for detecting the oil temperature of the lubricating oil, etc. Provide.

  In addition, pressure sensors 49 to 54 for detecting the hydraulic pressure of the forward hydraulic clutch 23, the reverse hydraulic clutch 24, and the hydraulic clutch packs of the hydraulic clutches 25 to 30 of the main transmission gears 6 to 11 are provided. Further, the auxiliary transmission position sensor 55 for detecting which of the auxiliary transmission gears 12, 13, 15 has the clutches 31, 32 in the engaged position and the forward / reverse operation lever for switching the forward / reverse clutches 23, 24 are used. ON / OFF forward / backward operation lever switch 56, accelerator memory switch 57 for resetting or setting the accelerator memory, accelerator memory adjusting switch 58 for adjusting the accelerator memory, PTO on / off switch 59 for turning on and off the PTO clutch 20, left and right A brake sensor 62 for detecting that the hydraulic clutch pack 60 of the side brake is operated by the solenoid valve 61 is provided.

  Further, a main shift increasing / decelerating switch 63 for increasing or decreasing the speed of the main transmission is provided in the grip portion of the auxiliary transmission lever. A clutch button is provided on the top of the grip portion of the auxiliary transmission lever, and the front and reverse hydraulic clutches 23 and 24 are disconnected by operating the solenoid valve 40 of the forward / reverse switching circuit by operating the clutch button. It is. In addition, an engine rotation sensor 64 and a vehicle speed sensor 68 for detecting the vehicle speed are provided.

  On the other hand, on the output side of the controller 44, in addition to the solenoid valves 36 to 43, the forward / reverse boost solenoid valve 65 for boosting the hydraulic pressure of the forward / reverse hydraulic clutches 23, 24, the first speed hydraulic clutch 25, A boost solenoid valve 66 for boosting the hydraulic clutch pack of the third speed hydraulic clutch 27, a boost solenoid valve 67 for boosting the hydraulic clutch pack of the second speed hydraulic clutch 26 and the fourth speed hydraulic clutch 28, and the like are provided.

  These boost solenoid valves 65, 66, and 67 can be operated as electromagnetic proportional solenoids by changing the clutch output pressure proportionally by changing and outputting the electromagnetic output.

  Here, the travel transmission control device according to the present invention is provided with a first speed gear 6 to a fourth speed gear 9 which are shifted in multiple stages by turning on and off of the first-speed hydraulic clutch 25 to the fourth-speed hydraulic clutch 28 in the form of a frictional multi-plate. Only in a low vehicle speed range where the speed is below a certain level, the first-speed gear 6 to the fourth-speed gear 9 can be braked by double engagement.

  The traveling transmission of the tractor is transmitted by selecting one transmission gear from the parallel first-speed gear 6 to fourth-speed gear 9 and meshing with other transmission gears in the front-rear direction. When the traveling vehicle speed is in a high vehicle speed range above a certain level, one of the first speed gear 6 to the fourth speed gear 9 other than the mesh transmission cannot be meshed, and the two gears are meshed. It is not possible. However, when the vehicle speed is in a low speed range below a certain level, the other first-speed gear 6 to the fourth-speed gear 9 other than during meshing transmission are engaged with the first-speed clutch 25 to the fourth-speed 28 of this transmission gear. By doing so, a double biting state can be achieved. Since the double-geared first-speed gear 6 to fourth-speed gear 9 are locked and do not rotate, the transmission to and after the transmission gear can be stopped to be in a braking state.

  Further, in the present embodiment, the double engagement braking is made possible when the sub-shift is at the low speed L or the medium speed M. Braking by double meshing of two or more sets of transmission gears within the same first gear 6 to fourth gear 9 is possible only in a low speed range where the vehicle speed is below a certain vehicle speed. Sub-shifting is possible at low speed L or medium speed M when it is likely to occur, and it is difficult to double-engage at high speed H or neutral N of sub-shifting, so that heavy loads on the sudden deceleration and transmission mechanism are heavy The configuration is not allowed.

  Further, the pressure of the first-speed hydraulic clutch 25 to the fourth-speed hydraulic clutch 28 at the time of the double engagement braking can be set to a low pressure so as to be in a half clutch state. The connection pressures of the first-speed gear 6 and the fourth-speed gear 9 to which the double-gear braking is applied and the first-speed hydraulic clutch 25 to the fourth-speed hydraulic clutch 28 are under a low pressure lower than the clutch pressure at the time of normal shifting. This is performed as a half-clutch state. Therefore, the first-speed hydraulic clutch 25 to the fourth-speed hydraulic clutch 28 are gradually connected, and the double-clutch braking of the transmission gear is performed slowly by slipping of the hydraulic clutch, so that the braking shock is reduced.

  Furthermore, the double-engagement braking is performed between the first-speed gear 6 to the fourth-speed gear 9 that are close to each other in vehicle speed. Double-engagement braking is performed by simultaneous meshing of a plurality of transmission gears in the same parallel first-speed gear 6 to fourth-speed gear 9, and these first-speed gear 6 to fourth-speed gear 9 are transmission gears having a close vehicle speed difference. Therefore, the double-gear braking is gradually performed by reducing the rotation difference between the double-gear transmission gears.

  Such a double engagement braking action of the travel transmission control device is performed as shown in the flowchart of FIG. When the vehicle body is running or stopped, the clutch pedal is being depressed, or the forward / reverse lever is being operated to the neutral position N, and the vehicle speed is in a low speed range below a certain vehicle speed (for example, 1 km / h), In addition, under conditions such that the sub-shift is at the medium speed M or low speed L position, any one of the first-speed hydraulic clutches 25 to the fourth-speed hydraulic clutch 28 of the first main transmission is At the same time, it is actuated to enter the double bite braking state. When the clutch pedal is depressed, when the clutch pedal switch 45 is turned on, the clutch pedal solenoid 40 is output and the forward / reverse hydraulic clutches 23 and 24 are turned off. At the same time, the Lo and Hi hydraulic clutches 29 and 30 of the second main transmission are also turned off (see FIGS. 5 and 6). Further, by operating the forward / reverse lever (linear lever) to the neutral position N, the forward and backward hydraulic clutches 23 and 24 can be disconnected.

  When the transmission clutch is thus disengaged, the vehicle speed sensor 68 detects a low vehicle speed range below a certain vehicle speed, and the auxiliary transmission gear 14 (low speed L) or the gear 15 (medium speed M) is on. Alternatively, when the turning operation is performed, the sub-shift position sensor 55 detects this, whereby the double biting action in the first main transmission is performed. At this time, if the output of the main shift is being output, this output is immediately turned OFF and the double biting output is performed.

  The operation timing of the hydraulic clutch when the clutch pedal is operated is as shown in FIG. 5. However, the output timing of the main transmission hydraulic clutch when the vehicle is traveling is as shown in FIG. After both the hydraulic clutches 23 and 24 and the Lo and Hi hydraulic clutches 29 and 30 are turned off (clutch disengagement) and the vehicle speed is reduced due to this traveling, the main gear shift is performed at two locations (for example, the first speed clutch 25 and the second gear). The speed clutch 26) is output.

  Further, as shown in FIG. 7, the output timing of the main transmission clutch when the vehicle body is stopped is two places (for example, the first-speed hydraulic clutch 25 and the second-speed hydraulic clutch 26) after the target shift position is once turned off. Outputs low pressure. This is because the hysteresis effect of the proportional valve appears unless the target shift position is once turned off. When the double bite output condition occurs, the main shift output during the current shift is temporarily turned OFF for a specified time (for example, 100 msec), and then the double bite output is performed. In the double engagement operation, the main shift target position output (main shift clutch) is changed to a low speed, and the main shift clutch output other than the target position is performed at a low pressure.

  This target position switching valve holds the target position until the clutch pedal operating state, which is a double biting output condition, is turned off, or the forward / reverse switching lever is in a neutral state and the vehicle speed is lowered to a low speed range below a certain level. . Such double-engaged main transmission hydraulic clutches such as the first-speed hydraulic clutch 25 and the second-speed hydraulic clutch 26, or the three-speed hydraulic clutch 27 and the fourth-speed hydraulic clutch 28, etc. Let me do it. When the main transmission target position is, for example, the first speed hydraulic clutch 25, the main transmission first speed hydraulic clutch 25 is turned off (disconnected) for the predetermined time of 100 msec due to the occurrence of the double-engagement operating condition of the main transmission hydraulic clutch. Then set the pressure to the set value. At this time, when the proportional valve 43 is controlled to be changed from the high pressure state to the low pressure side, the control pressure is often higher than the command pressure due to the hysteresis of the valve 43. Once it is turned off, it can be controlled from a low pressure like other clutches that are double-engaged. In this case, depending on the load of the auxiliary transmission lever, all the clutches may be turned off before the condition occurs. In addition, when this condition occurs, the double-speed clutch 26 to be double-engaged with respect to the target position is turned on. The target pressure at this time is set to a low pressure by making the axle torque converted values of the double-engaged clutch substantially the same. For example, 2.5 (kgf / cm2) for a 1-speed hydraulic clutch, 2.9 (kgf / cm2) for a 2-speed hydraulic clutch, 2.5 (kgf / cm2) for a 3-speed hydraulic clutch, 3.0 (kgf / cm @ 2).

  Next, the main shift is returned to the target position with full pressure (for example, 20 kgf / cm <2>) as the condition is released. The other valves are operated according to the position of the operation unit. The Lo valve 38 and the Hi valve 39 output to the target shift position.

  Such a double-engagement output is double-engaged by a transmission gear at a vehicle speed difference position close to the first-speed gear 6 to the fourth-speed gear 9 of the first main transmission immediately before the occurrence of the double-engagement output condition. When the speed change gear that is engaged immediately before is the first speed gear 6, the second speed gear 7 is engaged at the same time as the second speed gear 7. Further, when the immediately preceding transmission gear is the second speed gear 7, the second speed gear 7 and the first speed gear 6 are simultaneously meshed. Similarly, when the immediately preceding transmission gear is the third speed gear 8 or the fourth speed gear 9, the third speed gear 8 and the fourth speed gear 9 are simultaneously meshed.

  The double-engagement hydraulic circuit is switched to a low pressure range by boost solenoids 66 and 67. The first-speed hydraulic clutch 25 to the fourth-speed hydraulic clutch 25 of the first-speed gear 6 to the fourth-speed gear 9 that are double-engaged. 28 is put into operation by being pressed into a half-clutch state by a low oil pressure.

  The switching operation of the auxiliary transmission device by the auxiliary transmission lever 74 will be described with reference to the flowchart of FIG. As shown in FIG. 10, when the clutch button 73 provided on the grip portion of the auxiliary transmission lever 74 is pressed (ON), the forward / reverse hydraulic clutches 23 and 24 are operated to the disengagement side. In this state, the lever 74 is operated to a predetermined shift position while holding the auxiliary transmission lever 74.

  Subsequently, when the finger is released from the clutch button 73 and the button is released (ON → OFF), the forward side or the reverse side of the forward / reverse hydraulic clutch is boosted to allow travel at a predetermined sub-speed. Here, when the deceleration side is selected by the lever operation by the auxiliary transmission lever 74, the hydraulic clutch pressure is gradually increased after being held at a low pressure. In other words, after the initial output corresponding to the piston stroke of the clutch is performed at the timing when the clutch button 73 is changed from ON to OFF, the clutch pressure is gradually increased in accordance with the pressure increasing pattern corresponding to the shift position. With this configuration, it is possible to mitigate a shift shock due to the sub-shift.

  In the process of opening the clutch button 73 (ON → OFF) and connecting the hydraulic clutch, when the vehicle is in a traveling state and the subtransmission is operated to the deceleration side, the vehicle speed is changed to the shift position V. The forward or reverse hydraulic clutches 23 and 24 are connected depending on whether or not the speed Va is close to (for example, Va / V = 1.1). When V> Va, the connection of the hydraulic clutches 23 and 24 is limited. It is configured. In this way, sudden deceleration is not caused.

  Alternatively, when the hydraulic clutches 23 and 24 are connected with a prescribed pressure control pattern instead of the above-described restriction of the forward and reverse hydraulic clutches 23 and 24, the speed of the vehicle is not close to the shift position by operating on the deceleration side. In this case, the time t1 for holding at a low pressure is lengthened. If comprised in this way, power transmission will be performed gently. If the hydraulic clutches 23 and 24 are not engaged when the cut operation is performed on the downhill, the vehicle is accelerated and a dangerous state is generated. However, with the above configuration, the reduction ratio of the decelerated shift range gradually approaches and is safe. (FIG. 11B).

  Furthermore, the vehicle acceleration change is monitored, the pressure is gradually increased until an acceleration change greater than the specified value is applied, the pressure at that time is maintained, and then the pressure is increased to the specified pressure. . This configuration also ensures gentle power transmission and secures safety on the downhill (FIG. 12).

  In the above example, the forward and backward hydraulic clutches 23 and 24 are engaged / disengaged by operating the clutch button 73, but this is performed by the Hi hydraulic clutch 30 and the Lo hydraulic clutch 29 of the second main transmission. A configuration may be adopted, and any one of the first to fourth speed shifting hydraulic clutches of the first main transmission may be used. As to which of the first main transmission hydraulic clutches 25 to 28 is adopted, it is preferable that the hydraulic clutch of the currently shifted gear stage is engaged and interlocked.

  In FIG. 4, the work machine R lift cylinder 75 is provided in the upper half of the figure, and a proportional rise valve 76 and a proportional drop valve 77 are provided. In addition, one of the left and right lift arms 78 and 79 is provided with a horizontal cylinder 80 to perform horizontal horizontal control of the work machine R. By the way, a command signal is sent from the control unit to the solenoids 82 and 83 of the horizontal control switching valve 81 based on the detection result of the left and right horizontal sensors. When the horizontal cylinder is operated up to the stroke end, the state is predetermined. It is configured so that the horizontal output is stopped when the time continues. With this configuration, when the relief valve in the horizontal hydraulic circuit is operated, the flow rate to the working machine lifting cylinder 75 cannot be secured and it is difficult to move up and down. However, the configuration as described above ensures that even during the horizontal relief. The work machine can be raised and lowered.

  In addition, when the stroke sensor for detecting the stroke of the horizontal cylinder is abnormal, the working machine is not raised above a certain level by the operation of the lifting cylinder 75. With this configuration, even when the work machine is being tilted during work, the lift cylinder 75 does not raise the work machine to the highest position, so that interference between the machine and the work machine can be prevented.

Transmission mechanism diagram. Double biting control block. The flowchart. Hydraulic circuit diagram. The block diagram of a hydraulic clutch. Time chart of double biting control. Time chart of double biting control. A side view of a tractor. Time chart of clutch button operation. The perspective view of an auxiliary transmission lever part. (A) (B) Hydraulic clutch pressure increase graph. The graph which shows an example of vehicle speed-speed and an acceleration relationship, and an example of pressure | voltage rise of a hydraulic clutch.

Explanation of symbols

4 Forward gear 5 Reverse gear 6 First gear 7 Second gear 8 Third gear 9 Fourth gear 10 Hi gear 11 Lo gear 12 High speed gear 13 Medium speed gear 14 Neutral gear 15 Low speed gear 23 Forward clutch 24 Reverse clutch 25 First speed Clutch 26 Second speed clutch 27 Third speed clutch 28 Fourth speed clutch 29 Lo clutch 30 Hi clutch 66 Boost solenoid valve 67 Boost solenoid valve 73 Clutch button 74 Sub-shift lever

Claims (2)

A transmission gear (6-9) is provided for multi-stage shifting by turning on and off the hydraulic clutch (25-28), and can be braked by double engagement of the transmission gear (6-9) when the clutch pedal (45) is depressed. In the travel transmission device of the constructed work vehicle, when the clutch button (73) provided on the auxiliary transmission lever (74) is pushed, the transmission gear (6-9) is not double-engaged and the hydraulic clutch (25- 28) A traveling transmission device for a work vehicle provided with a controller (44) for interlocking a predetermined clutch of the above-mentioned clutch to the disengagement side. When the work vehicle detects the traveling state and shifts the sub-transmission device to the deceleration side, the controller (44) that interlocks the hydraulic clutch to the entry side when the detected speed of the work vehicle is decelerated to a speed near the shift position. The traveling transmission device for a work vehicle according to claim 1, wherein:

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