JP4260093B2 - Work vehicle speed maintenance structure - Google Patents

Description

  The present invention enables a continuously variable transmission that is held back to a neutral state by the action of the neutral return device, and forward shift operation and reverse shift operation of the continuously variable transmission that resists the action of the neutral return device. And a speed maintaining device that enables the continuously variable transmission to be maintained in a desired forward shift state against the action of the neutral return device, A relay rocking member in which the speed maintaining device is pivoted in the forward speed increasing operation direction from the retracted position of the speed setting lever, and an operation member interlocked with the speed setting lever is linked to the continuously variable transmission. By pressing the button, the continuously variable transmission is moved forward against the action of the neutral return device, and the speed setting lever is operated in the forward speed setting region by the action of the holding mechanism. To hold in position Ri relates speed maintenance structure of the working vehicle is arranged to prevent the return to the neutral state from the forward shifting state of the continuously variable transmission by the action of the neutral return device.

  In the speed maintaining structure of the work vehicle as described above, the swinging region of the relay swinging member linked to the continuously variable transmission is linked to the swinging operation of the speed setting lever to the retracted position. By shifting to a position deviating from the position, the speed setting by the speed maintaining device is released, and the forward shift operation and the reverse shift operation of the continuously variable transmission by the shift pedal are allowed.

Conventionally, when the retracting position of the speed setting lever is operated to the retracted position, the operating member is moved away from the swinging region of the relay swinging member in the swinging direction of the relay swinging member. When the speed setting lever is set to a position far away from the forward speed setting area in the forward deceleration direction (reverse speed increasing direction), or when the speed setting lever is operated to the retracted position, the operating member swings the relay swing member. It has been considered that the position of the speed setting lever is set to a position deviated to the left and right side so as to deviate from the swing area of the relay swing member in a direction orthogonal to the moving direction (for example, Patent Documents). 1 and 2).
JP 2004-211776 A JP 2001-82597 A

  In the above prior art, when the retracting position of the speed setting lever is set at a position far away from the forward speed setting region of the speed setting lever in the forward deceleration direction, the speed setting lever is set on the limited lever guide. As the operation area, not only the forward speed setting area but also a space allowing the swing of the relay swing member linked to the reverse shift operation of the continuously variable transmission by the shift pedal is formed between the relay swing member and the operation member. It is also necessary to secure an area for doing this. Therefore, the forward speed setting area on the lever guide is considerably narrowed, and thereby, when establishing the operation of the speed setting lever, if the operation angle of the speed setting lever is widened to facilitate precise speed setting, Accordingly, the speed setting lever is shortened and requires a large operating force. Conversely, if the length of the speed setting lever is increased in order to reduce the operating force, the operating angle of the speed setting lever becomes narrow accordingly, making it difficult to perform precise speed setting.

  On the other hand, when the retracting position of the speed setting lever is set to a position that deviates to the left or right side from the forward speed setting area of the speed setting lever, the speed setting lever can be swung in the left / right direction. It is necessary to configure in a dynamic manner, which leads to a complicated configuration, and at the time of speed setting operation, the speed setting lever is swung in the left-right direction and swinging in the front-rear direction. Because it is necessary, there is room for improvement in terms of operability.

  An object of the present invention is to provide a speed maintaining structure for a work vehicle that is capable of precise speed setting operation and reduction of operating force without causing complication of the configuration, and that is excellent in operability.

As means for solving the above-mentioned problems, in the invention according to claim 1 of the present invention, the continuously variable transmission that is held back to the neutral state by the action of the neutral return device, and the action of the neutral return device The continuously variable transmission operated against the continuously variable transmission and the continuously variable transmission resisting the action of the neutral return device so that the forward transmission and the reverse transmission can be operated against the A speed maintaining device that enables the device to be maintained in a desired forward shift state, and the speed maintaining lever is operated by swinging from the retracted position of the speed setting lever in the forward speed increasing operation direction. An operation member that is linked to the continuously variable transmission device, by pressing the relay rocking member that is linked to the continuously variable transmission device, thereby operating the continuously variable transmission device forwardly against the action of the neutral return device; and The front of the holding mechanism By holding the speed setting lever at a desired operation position in the forward speed setting region, it is configured to prevent the continuously variable transmission from returning from the forward shift state to the neutral state due to the action of the neutral return device. at a rate maintaining the structure of a working vehicle, said relay swinging member, thereby rotatably supported on the rotation shaft of the speed setting lever, a pre SL relay oscillating member, it can relatively swing the relay swinging member The auxiliary oscillating member is connected to the continuously variable transmission via the auxiliary oscillating member, and the operating member is engaged with the auxiliary oscillating member in conjunction with the operation of the speed setting lever to the forward speed setting region. In addition, the auxiliary oscillating member restricts the oscillating displacement of the relay oscillating member in the reverse speed increasing operation direction with respect to the relay oscillating member, and interlocks with the operation of the speed setting lever to the retracted position. Engage with the swing member Dividing it, it is arranged to release the swing restriction of the reverse speed increasing operation direction with respect to the relay swinging member of the auxiliary swing member.

  According to this configuration, when the speed setting lever is swung in the forward speed setting region, the operation member maintains the engaged state with the auxiliary rocking member in conjunction with the operation. The relay swing member is pressed with an operation amount corresponding to the operation amount of the speed setting lever while restricting the swing displacement from the predetermined swing posture with respect to the relay swing member to the reverse acceleration operation direction (forward deceleration operation direction). Along with this, the continuously variable transmission that is linked to the relay swing member via the auxiliary swing member is shifted to the forward shift state according to the operation position of the speed setting lever, In addition, the shift pedal operated and linked to the continuously variable transmission is oscillated and displaced to the forward shift operation state according to the operation position of the speed setting lever, and the operation of the speed setting lever by the operation of the holding mechanism Forward variable speed of continuously variable transmission And the forward speed change operation states of the shift pedal is maintained.

  In this speed maintaining state, the operation member that is linked to the speed setting lever that is operated and held by the action of the holding mechanism restricts the swing displacement of the auxiliary swing member in the reverse acceleration operation direction (forward deceleration operation direction). On the other hand, since the relay swing member is merely pressed, the speed change operation by the speed change pedal on the forward acceleration side is allowed from the set speed by the speed setting lever.

  On the other hand, when the speed setting lever is swung to the retracted position, the operation member releases the engagement with the auxiliary rocking member in conjunction with the operation, and the auxiliary rocking member regulated by the engagement. Since the oscillating displacement from the predetermined oscillating posture with respect to the relay oscillating member to the reverse acceleration operating direction (forward / decelerating operating direction) is allowed, the continuously variable transmission linked to the auxiliary oscillating member is The neutral return device returns and holds the neutral state, and the forward transmission operation and the reverse transmission operation of the continuously variable transmission are allowed against the operation of the neutral return device by the shift pedal.

  That is, it is possible to switch between the engagement state and the disengagement state of the operation member with respect to the auxiliary swing member in the direction along the region from the forward speed setting region in which the forward speed can be set by the speed setting lever. The position separated by the extremely small operation area can be set to the retracted position of the speed setting lever that releases the setting by the speed setting lever and enables the forward / reverse shift operation by the shift pedal.

  As a result, when the speed setting lever is swung, the vehicle moves forward at the speed set by the speed setting lever. The speed setting lever for setting the swing direction of the speed setting lever when switching the travel state of the vehicle body to the normal driving state and the forward speed in the constant speed forward state by the swing operation of the speed setting lever The operation range required for switching the running state is the forward speed setting region on a limited lever guide, while making it easy to perform a series of operations using the speed setting lever. Between the retracted position of the speed setting lever and the forward speed setting region in the direction along the direction of the As a result, a cross swing type is used as the speed setting lever, and the retracted position of the speed setting lever is moved away from the forward speed setting area of the speed setting lever. Without adopting a configuration such as setting to a certain position, it is possible to secure a wide area as the forward speed setting area of the speed setting lever on the limited lever guide, so the length of the speed setting lever can be increased. While the operation force can be reduced, a wide angle can be secured as the operation angle of the speed setting lever, and it becomes easy to perform precise speed setting by the speed setting lever.

  Therefore, it is possible to set the precise forward speed by the speed setting lever without complicating the configuration, and the operation force required for the setting operation and the switching operation between the normal traveling state and the constant speed forward state is reduced. It is possible to provide a speed maintaining structure for a work vehicle with excellent operability, which can make the operation directions coincide with each other while facilitating the reduction, and can facilitate the series of operations. .

  According to a second aspect of the present invention, in the invention according to the first aspect, the operation member is configured to press the relay rocking member via the auxiliary rocking member. It is.

  According to this configuration, when the speed setting lever is swung in the forward speed setting region, the operating member maintains the engaged state with the auxiliary rocking member in conjunction with the operation, and this auxiliary rocking The auxiliary swing member with an operation amount corresponding to the operation amount of the speed setting lever while restricting the swing displacement of the member from the predetermined swing posture with respect to the relay swing member in the reverse acceleration operation direction (forward deceleration operation direction) The relay rocking member is pressed through this.

  In other words, the engaging portion of the operation member that acts on the auxiliary swing member can be effectively used as an operation unit for pressing the relay swing member, and the operation member directly presses the relay swing member. As in the case of adopting such a configuration, it is not necessary to separately provide the operation member with an engaging portion for the auxiliary swing member and an operation portion for pressing the relay swing member.

  Therefore, it is possible to provide a speed maintaining structure for a work vehicle that is excellent in operability while simplifying and compacting the speed maintaining structure by simplifying the operating member.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the one end portion of the linkage member that links the auxiliary swing member to the continuously variable transmission is connected to the auxiliary portion. The swing member and the operation member are linked to the auxiliary swing member so as to straddle the operation member so as to prevent relative displacement of the swing member and the operation member in the swing axis direction.

  According to this configuration, even if each of the linking portions of the operation member and the auxiliary swing member is formed of a sheet metal having a narrow width, the link between the operation member and the auxiliary swing member due to play due to tolerances or the like is caused. Therefore, the operation member and the auxiliary swing member can be maintained in an appropriate linked state or in a linkable state.

  Therefore, good speed setting operation by the speed setting lever is achieved while reducing the cost by using a narrow metal plate or the like for the linking part of the operating member and the auxiliary swinging member, and simplifying and downsizing the speed maintaining structure. It is possible to provide a work vehicle speed maintaining structure with excellent operability.

  FIG. 1 shows an entire side surface of a tractor which is an example of a work vehicle, and FIG. 2 shows an entire plane of the tractor. In addition, the boarding operation part 5 is formed with the steering wheel 3 and the driver seat 4 in the latter half thereof, and the power from the engine 1 is provided as a main transmission via the main clutch 6. A pair of left and right front wheels 9 and rear wheels are transmitted to the hydraulic continuously variable transmission 7 through the traveling transmission system built in the transmission case 8 for traveling. 10 and the non-transmission power from the hydrostatic continuously variable transmission 7 is used for work through the work transmission system built in the transmission case 8 and is provided at the rear end of the transmission case 8. To transmit to the take-out shaft 11 It is configured.

  The rear part of the transmission case 8 is provided with a pair of left and right lift arms 12 that are driven to swing up and down by hydraulic pressure, and a link mechanism 13 that swings in conjunction with the lift arms 12. The working device, the loading platform, and the like can be connected and installed, and the power extracted from the power take-out shaft 11 can be transmitted to the working device connected to the link mechanism 13.

  Although illustration is omitted, the traveling transmission system is configured to include a gear-type transmission provided as an auxiliary transmission, a rear wheel differential, an auxiliary clutch for the front wheels, and the work transmission system is a work transmission system. It is configured with a clutch and the like.

  As shown in FIGS. 1 to 3, the hydrostatic continuously variable transmission 7 is returned and held in the neutral state by the action of the neutral return device 14 provided on the right side thereof. The neutral return device 14 is provided with a roller 17 provided at the free end of the swing arm 16 in a V-shaped cam recess 15A formed on the cam arm 15 integrally coupled to the trunnion shaft 7a of the hydrostatic continuously variable transmission 7. The hydrostatic continuously variable transmission device 7 is configured to return and hold to the neutral state by engaging and energizing with the action of the tension spring 18.

  The arm portion 15B of the cam arm 15 is operatively linked via a rod 20 to a speed change pedal 19 provided at the right front portion of the boarding operation portion 5, and to a speed maintaining device 21 provided at the right side portion of the mission case 8. The operation is linked through a link member 22 whose length can be adjusted.

  The shift pedal 19 has a balance-like shape that can be swung around a left-right support shaft 23 as a fulcrum. The stepping operation on the front side of the shift pedal 19 resists the action of the neutral return device 14. The forward shift operation of the step transmission 7 can be performed, and the reverse shift operation of the hydrostatic continuously variable transmission 7 that resists the action of the neutral return device 14 can be performed by the stepping operation on the rear side.

  The speed maintaining device 21 is a lever operation type that performs the forward shift operation of the hydrostatic continuously variable transmission 7 against the action of the neutral return device 14 by the swing operation of the speed setting lever 24 in the forward speed setting region. The friction setting mechanism 25 is configured to hold the speed setting lever 24 at a desired operation position in the forward speed setting region against the action of the neutral return device 14 by the action of the friction type holding mechanism 25. By maintaining the friction, the forward shift state of the hydrostatic continuously variable transmission 7 according to the operation position of the speed setting lever 24 in the forward speed setting region is maintained and the constant speed forward state appears.

  As shown in FIGS. 3 to 13, in the speed maintaining device 21, the speed setting lever 24 can be integrally interlocked with a cylindrical rotary shaft 27 via an operation member 26 made of sheet metal formed in a square shape in side view. With this rotating shaft 27 as a fulcrum, the forward / backward swing operation in the forward speed setting region and the forward / backward swing operation over the retracted position and the forward speed setting region set behind this forward speed setting region And done.

  The rotary shaft 27 is supported by plate-like left and right support members 28 and 29 that are bolted to the right side of the mission case 8 so as to be relatively rotatable and relatively slidable. A boss 30A of the relay swing member 30 is supported on the rotary shaft 27 so as to be relatively rotatable, and a left and right fulcrum pin 31 is fixed to the free end of the relay swing member 30. 31 is provided with a boss portion 32B of an auxiliary swing member 32 having a bifurcated sheet metal swing portion 32A, which is relatively rotatable, and a linkage pin is provided at one free end of the swing portion 32A. One end portion 22 </ b> A of the linking member 22 is connected via 33.

  The auxiliary oscillating member 32 is provided with a left and right engaging pin 34 guided by a guide hole 28A formed in the left support member 28 at the other free end of the oscillating portion 32A. The locking pin 34 comes into contact with the upper edge of the guide hole 28A by the action of the torsion spring 35 that is externally fitted to the boss portion 32B of the auxiliary oscillating member 32 in a state of being passed over the relay oscillating member 30. Thus, the relay member is held in a predetermined reference posture with respect to the relay swing member 30.

  The operating member 26 is placed at the rear end of the lower free end thereof at the other free end of the swinging portion 32A of the auxiliary swinging member 32 in accordance with the swinging operation from the retracted position of the speed setting lever 24 to the forward speed setting region. Engagement prevents the auxiliary oscillating member 32 from oscillating displacement relative to the relay oscillating member 30, and the oscillating portion is associated with the oscillating operation of the speed setting lever 24 from the forward speed setting region to the retracted position. An engagement recess 26A is formed that releases the engagement of the other swing end of 32A and allows the swinging displacement of the auxiliary swinging member 32 relative to the relay swinging member 30, and the speed setting lever 24 sets the forward speed. When the swinging operation is performed in the area, the auxiliary swinging member 32 is controlled by the operation amount corresponding to the operation position of the speed setting lever 24 in the forward speed setting region while preventing the swinging displacement of the auxiliary swinging member 32 with respect to the relay swinging member 30. Pressing the moving member 32 to relay The member 30 is swung displaced in forward shift operation area rearward from the reference posture (corresponding pose a neutral state of the hydrostatic continuously variable transmission 7).

  The guide hole 28 </ b> A is rearward from a position corresponding to the reference position of the locking pin 34 in the left support member 28 (position corresponding to the neutral state of the hydrostatic continuously variable transmission 7) with the rotary shaft 27 as a fulcrum. In a state where the arcuate forward shift guide portion 28a formed toward the center and the relay swing member 30 are in the reference posture, the reference of the locking pin 34 in the left support member 28 with the fulcrum pin 31 as a fulcrum. An arcuate reverse shift guide portion 28b formed downward from a position corresponding to the position and an assembly opening portion 28c formed upward from the rear end of the forward shift guide portion 28a are provided. It has been.

  The left support member 28 is provided with a stopper 36 that restricts the speed setting lever 24 from swinging backward from the retracted position in contact with the operation member 26, and the operation member 26 and the left support member 28. A tension spring 37 that swings and urges the speed setting lever 24 toward the stopper 36 is provided.

  The linking member 22 is operated so that one end portion 22A of the linking member 22 prevents relative displacement between the swinging portion 32A of the auxiliary swinging member 32 and the operation member 26 in the left-right direction that is the direction of the swinging axis. In a state of straddling the member 26, it is formed in a U-shape in a plan view linked to the swinging portion 32A of the auxiliary swinging member 32, and at one end portion 22A of the hydrostatic stepless by the shift pedal 19. A long hole 22 </ b> B is formed as a flexible portion that allows relative displacement of the linkage member 22 with respect to the auxiliary rocking member 32 during forward shift operation of the transmission 7.

  The holding mechanism 25 includes a plurality of friction disks 38 and a plurality of fixed members whose rotations are prevented by a fixed shaft 65 extending between the left and right support members 28 and 29 between the operation member 26 and the right support member 29 on the rotation shaft 27. A plurality of oscillating plates 40 that oscillate integrally with the operation member 26 by fitting between the plate 39 and a linking pin 26 </ b> B protruding from the operation member 26 are externally fitted, and the urging mechanism 41 presses the rotary shaft 27. In operation, the speed setting lever 24 is neutralized by a frictional holding force obtained by pressing the operating member 26 fixed to the rotary shaft 27 against the right support member 29 through the disk 38 and the plates 39 and 40. Against the action of the return device 14 and the action of the tension spring 37, the desired operation position in the forward shift operation region is held.

  The urging mechanism 41 slides integrally with the rotating shaft 27 with respect to the left and right support members 28 and 29, and allows the relative rotation of the rotating shaft 27, and swings in the sliding direction. A swing arm 43 that is pin-connected to the left support member 28 so as to be able to be connected, a linkage pin 44 that interlocks and connects the slide member 42 to the swing arm 43, and the swing arm 43 is connected to the right support member 29. And the like, and the sliding member 42 is slid through the linkage pin 44 by the swinging of the swinging arm 43 by the action of the pulling spring 45, thereby rotating the rotating shaft. 27, the operating member 26 is pressed toward the right support member 29.

  In the swing arm 43, the distance L1 from the swing support point P0 to the force point P1 that receives the action of the pulling spring 45 is the distance from the swing support point P0 to the action point P2 that acts on the sliding member 42 and the rotary shaft 27. It is set so as to be larger than L2, and as a result, a higher frictional holding force can be obtained than when the rotary shaft 27 is directly slid by the tension spring 45.

  The swing arm 43 is formed with a long hole 43 </ b> A as an interchangeable portion that allows relative displacement of the linkage pin 44 with respect to the swing arm 43 in conjunction with the swing arm 43 and the sliding member 42.

Holding mechanism 25, in front of the speed-change pedal 19 in the driver's section 5, the operation of depressing the left and right direction of the support shaft 46 rocking operation that the fulcrum left and right that are deployed to allow the brake pedals 47, 48 The brakes 47 and 48 are linked to the left and right brake pedals 47 and 48 via a release linkage mechanism 49 so as to release the friction holding of the speed setting lever 24 at the time of braking deceleration.

  The release linking mechanism 49 is a right-hand swing that integrally swings with the other end portion of the left link 51 that is pin-connected to a left swing arm 50 that swings integrally with the left brake pedal 47 and a right brake pedal 48. A link link 54, a first swing arm 55, a second swing arm 56, a length-adjustable first rod 57, a first rod 57, and the other end portion of the right link 53, one end of which is pin-connected to the moving arm 52. When the left and right brake pedals 47 and 48 are depressed by being linked to the release arm 60 provided on the left support member 28 via the three swing arms 58 and the second rod 59. The left and right links 51 and 53 and the linkage link 54 associated with the operation absorb the operating force at that time, so that the holding state of the speed setting lever 24 by the holding mechanism 25 is maintained. Both shakes When the key pedals 47 and 48 are depressed, the operating force at that time is transmitted to the release arm 60 by the integrated displacement of the left and right links 51 and 53 and the linkage link 54 accompanying the operation, and is released by the operating force. The holding state of the speed setting lever 24 by the holding mechanism 25 is released by swinging the arm 60 and swinging the swing arm 43 in a direction against the action of the pulling spring 45.

  In the swing arm 43, the distance L3 from the swing support point P0 to the force point P3 that receives the action of the release arm 60 is greater than the distance L1 from the swing support point P0 to the force point P1 that receives the action of the pulling spring 45. Thus, the rotational shaft 27 can be slid in a direction against the action of the pulling spring 45 with an operating force smaller than the urging force of the pulling spring 45, and the speed setting lever The frictional holding of 24 can be easily released.

  The linkage link 54 has a long hole 54A as a flexible portion that allows relative swinging of the left and right links 51 and 53 and the linkage link 54 when either one of the left and right brake pedals 47 and 48 is depressed. In addition, the first swing arm 55 is formed with a long hole (not shown) as an interchangeable portion that allows relative interlocking swing between the first swing arm 55 and the second swing arm 56. ) Is formed.

  The left and right brake pedals 47 and 48 are linked to the operation shafts 62A of the corresponding left and right braking devices 62 built in the mission case 8 via the linkage mechanism 63, and either one of the brake pedals 47 and 48 is depressed. By operating the corresponding braking device 62 by operating, the braking turning with the rear wheel 10 braked by the braking device 62 inside the turning can be performed, and the left and right brake pedals 47 and 48 are depressed to operate the left and right By operating both braking devices 62, braking deceleration that brakes the left and right rear wheels 10 with these braking devices 62 can be performed.

With the above configuration, when the speed setting lever 24 is swung from the retracted position to the forward speed setting region provided in the forward speed increasing operation direction with the left and right rotating shaft 27 as a fulcrum, the operating member 26 is operated. The engaging recess 26A engages with the other free end of the auxiliary swinging member 32 to prevent the swinging displacement of the auxiliary swinging member 32 relative to the relay swinging member 30, thereby setting the speed. When the lever 24 is swung in the forward speed setting area, the operation member 26 is relayed via the auxiliary rocking member 32 with an operation amount corresponding to the operation position of the speed setting lever 24 in the forward speed setting area. The oscillating member 30 is pressed and oscillated along the forward shift guide portion 28a of the guide hole 28A, and the operation amount corresponding to the oscillating operation amount of the relay oscillating member 30 at this time is a hydrostatic non-hydraulic type. The step transmission 7 changes forward. Is operated, the forward shifting This state is maintained by the frictional retention of the speed setting lever 24 by the holding mechanism 25, the result, it is possible to run the vehicle at a forward speed corresponding to the operating position of the speed setting lever 24.

  In this constant speed forward state, the shift pedal 19 operatively linked to the hydrostatic continuously variable transmission 7 is moved to the operation position corresponding to the shift state of the hydrostatic continuously variable transmission 7 at this time. As a result, the forward shift operation by the depressing operation on the forward acceleration side from the holding position of the shift pedal 19 becomes possible.

  In addition, when the left and right brake pedals 47 and 48 are depressed in this constant speed forward state, the rear wheel 10 corresponding to the braking force corresponding to the amount of depression at that time is maintained while maintaining the constant speed forward state. The braking turning state to be braked can appear, and when the stepping operation is released, the braking turning state can be returned to the constant speed forward state.

  Furthermore, when the left and right brake pedals 47 and 48 are depressed in this constant speed forward state, the left and right braking devices 62 brake the left and right rear wheels 10, while the operating force is applied via the release linkage mechanism 49. By being transmitted to the holding mechanism 25 and releasing the friction holding of the speed setting lever 24 by the holding mechanism 25, the constant speed forward state is switched to the normal running state, and the speed setting lever 24 is retracted by the action of the tension spring 37. The relay oscillating member 30 is oscillated along the guide portion 28a for the forward shift of the guide hole 28A together with the auxiliary oscillating member 32 by the operation of the neutral return device 14 and returned to the reference posture. As a result, the hydrostatic continuously variable transmission 7 returns to the neutral state, and as a result, the braking deceleration by the left and right braking devices 62 can be satisfactorily performed.

  In this normal running state, the speed setting lever 24 is located at the retracted position, so that the engagement between the engaging recess 26A of the operating member 26 and the other free end of the auxiliary swinging member 32 is released, and relaying is performed. Since the oscillating displacement of the auxiliary oscillating member 32 relative to the oscillating member 30 is allowed, when the reverse shift operation of the hydrostatic continuously variable transmission 7 by the shift pedal 19 is performed, the torsion spring 35 is interlocked with the operation. Against this action, the auxiliary rocking member 32 is rocked and displaced with respect to the relay rocking member 30 along the reverse shift guide portion 28b of the guide hole 28A. The standard posture will be maintained.

  That is, in this normal running state, the engagement between the operation member 26 and the auxiliary swing member 32 is released to allow the swing displacement of the auxiliary swing member 32 relative to the relay swing member 30. Only by securing an extremely short operation area between the forward shift operation area in the lever guide 64 (see FIG. 2) and the retracted position so that an extremely small gap is formed, the shift pedal 19 in the normal traveling state is used. The reverse shift operation of the hydrostatic continuously variable transmission 7 can be performed satisfactorily.

  In addition, this makes it possible to secure a wide area as the forward speed setting area of the speed setting lever 24 on the lever guide 64 having a limited size, and thus the length of the speed setting lever 24 is lengthened to reduce the operating force. However, a wide angle can be secured as the operating angle of the speed setting lever 24, and it becomes easy to set a precise forward speed by the speed setting lever 24.

  On the other hand, during forward shift operation of the hydrostatic continuously variable transmission 7 by the shift pedal 19 in the normal traveling state, the operating force is absorbed by the long hole 22B formed in the one end portion 22A of the linkage member 22, Interlocking rocking of the relay rocking member 30 and the auxiliary rocking member 32 accompanying the operation can be prevented.

[Another embodiment]
Hereinafter, other embodiments of the present invention will be listed.
[1] The work vehicle may be an agricultural work vehicle such as a rice transplanter or a combiner, a construction work vehicle such as a wheel loader, a lawn mower or a transport vehicle.

[2] The holding mechanism 25 may be configured to latch and hold the speed setting lever 24.

[3] The operation member 26 is formed to be engaged with the auxiliary rocking member 32 so as to restrict only the rocking displacement of the auxiliary rocking member 32 in the reverse speed increasing operation direction with respect to the relay rocking member 30. May be. In this case, the opening 28c as exemplified in the above embodiment is not formed in the guide hole 28A, or an opening 28c having a shape different from that of the opening 28c exemplified in the above embodiment is formed. It is desirable to make improvements such as

[4] The operation member 26 may be configured to directly press the relay swing member 30 without using the auxiliary swing member 32.

[5] The one end 22 </ b> A of the linkage member 22 may be linked to the auxiliary swing member 32 without straddling the operation member 26. In this case, a pressing operation of the auxiliary rocking member 32 by the operation member 26 or an operation member 26 by the relative displacement of the auxiliary rocking member 32 and the operation member 26 in the direction of the rocking axis. To improve the engagement with the auxiliary oscillating member 32, any one of the engaging portion and the pressing portion or both engaging portions and the pressing portion are formed to be wide. Is desirable.

[6] The relay rocking member 30 or the auxiliary rocking member 32 or both of them may be rocked in conjunction with the forward shifting operation of the hydrostatic continuously variable transmission 7 by the shift pedal 19. .

Overall side view of tractor Overall view of the tractor Side view of essential parts showing operation system for continuously variable transmission Side view of essential parts showing a state in which the speed change device is not operated by releasing the setting of the speed maintenance device Side view of a portion showing a state in which the speed increasing operation of the speed change pedal is performed by releasing the setting of the speed maintaining device Side view of the main part showing a state in which the speed increasing operation of the speed change pedal is performed reversely by releasing the setting of the speed maintaining device Side view of the main part showing the state where the speed change device is not operated at the zero speed setting of the speed maintaining device Side view of the main part showing the state in which the speed increasing operation of the speed change pedal is performed with the speed maintaining device set to zero speed Side view of the main part showing the state where the speed change device is not operated in the forward setting of the speed maintaining device Exploded perspective view of essential parts of speed maintenance device Vertical side view of the main part showing the configuration of the speed maintenance device Longitudinal rear view of main part showing holding structure of speed maintenance device Cross-sectional plan view of the main part showing the release structure of the speed maintenance device

Explanation of symbols

7 continuously variable transmission 14 neutral return device 19 shift pedal 21 speed maintaining device 22 linkage member 22A one end 24 speed setting lever 25 holding mechanism 26 operation member
27 Rotating shaft 30 Relay swing member 32 Auxiliary swing member

Claims (3)

The continuously variable transmission that is returned and held in the neutral state by the action of the neutral return device, and the continuously variable transmission operation of the continuously variable transmission that resists the action of the neutral return device and the reverse shift operation. A speed change pedal that is operatively linked to the step transmission, and a speed maintenance device that enables the continuously variable transmission to be maintained in a desired forward shift state against the action of the neutral return device;
A relay rocking member in which the speed maintaining device is pivoted in the forward speed increasing operation direction from the retracted position of the speed setting lever, and an operation member interlocked with the speed setting lever is linked to the continuously variable transmission. By pressing the button, the continuously variable transmission is moved forward against the action of the neutral return device, and the speed setting lever is operated in the forward speed setting region by the action of the holding mechanism. A work vehicle speed maintaining structure configured to prevent the continuously variable transmission from returning from a forward shift state to a neutral state by the action of the neutral return device by being held in position,
The relay swinging member, thereby rotatably supported on the rotation shaft of the speed setting lever, a pre SL relay swing member, through an auxiliary swing member equipped to be relatively swing the relay swinging member And linked to the continuously variable transmission,
The operation member engages with the auxiliary rocking member in conjunction with the operation of the speed setting lever to the forward speed setting region, and the reverse rocking operation of the auxiliary rocking member with respect to the relay rocking member is performed. In conjunction with the operation of the speed setting lever to the retracted position, the engagement with the auxiliary swing member is released, and the relay of the auxiliary swing member is controlled. A speed maintaining structure for a work vehicle configured to release a swing restriction in a reverse acceleration operation direction with respect to a swing member.
  The work vehicle speed maintaining structure according to claim 1, wherein the operating member is configured to press the relay rocking member via the auxiliary rocking member.   One end portion of the linkage member that links the auxiliary swing member to the continuously variable transmission so as to prevent relative displacement of the auxiliary swing member and the operation member in the swing axis direction. The work vehicle speed maintaining structure according to claim 1, wherein the speed maintaining structure is linked to the auxiliary swing member across the operation member.

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