JP2010260462A - Utility vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a utility vehicle with an improved safety that can turn stably, smoothly and quickly by regulating sliding of a front wheel speed-increase operating member by a front wheel speed-increase regulating member when an auxiliary transmission is placed in a high speed range. <P>SOLUTION: The utility vehicle includes: an auxiliary transmission shaft 76 for transmitting a rotating motive force from an engine 40 via a primary shaft 51 and primary transmission shaft 61 and for permitting a gear shift by an operation of an auxiliary transmission operating member 8; a front wheel driving output shaft 85 for transmitting the rotating motive force of the auxiliary transmission shaft 76 to front wheels 3; and a front wheel speed-increase drive switching mechanism 88 provided to the front wheel driving output shaft 85 and for increasing a circumferential speed of the front wheels 3 by an operation of a front wheel speed-increase operating member 9 according to steered angles of the front wheels 3 when the vehicle travels in a front-and-rear wheel driving state. The vehicle also includes, between the auxiliary transmission operating member 8 and the front wheel speed-increase operating member 9, a front wheel speed-increase regulating mechanism 93 including a front wheel speed-increase regulating member 95 for regulating sliding of the front wheel speed-increase operating member 9 via a link member 94 linked with the auxiliary transmission operating member 8. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention transmits the rotational power from the engine via the main shaft and the main transmission shaft, and transmits the rotational power of the auxiliary transmission shaft to the front wheels, which enables the transmission to be shifted by operating the auxiliary transmission operation member. By operating the front wheel drive output shaft and the front wheel speed increasing operation member provided on the front wheel drive output shaft, the front wheel peripheral speed is increased according to the steering angle of the front wheel when the vehicle is driven in the front and rear wheel drive state. More specifically, the present invention relates to a work vehicle including a front wheel speed increasing drive switching mechanism, and more specifically, a front wheel speed increasing operation member and a front wheel speed increasing operation member are connected to each other via a link member linked to the sub speed shifting operation member. The present invention relates to a work vehicle including a front wheel speed increasing check mechanism including a front wheel speed increasing check member that restricts sliding of a speed operating member.

  Conventionally, a work vehicle such as a wheel type tractor can be switched between a two-wheel drive state and a four-wheel drive state, and in a four-wheel drive state in which the steering angle of the front wheel exceeds a predetermined value, By operating a front wheel double speed switching lever or the like provided on the front wheel, the peripheral speed of the front wheel is driven at a double speed of the peripheral speed of the rear wheel so that the vehicle can turn quickly and smoothly (for example, Patent Documents 1 and 2). is there. In addition, a shift lock device that is operated by electrical means at the third speed position, which is the high speed region of the sub-shift, is provided on the sub-shift lever, and the four-wheel drive on / off switch is turned on so that the front-wheel double-speed device can be operated. The operation of the shift lock device restricts the sliding of the auxiliary transmission lever to the high speed position, so that the vehicle suddenly enters a high speed running state in the operating state of the front wheel double speed device, and the posture and behavior of the vehicle body are changed. Some have a safety device that prevents instability (Patent Document 3).

Japanese Utility Model Publication No.2-2235 Japanese Utility Model Publication No. 5-5542 JP 2000-309228 A

However, in such a work vehicle, for example, in a four-wheel drive state, when the auxiliary transmission shaft is at a high speed (the auxiliary transmission lever is at a high gear position of 3rd speed or higher), the front wheel double speed lever is slid to the operating (on) side. If the steering wheel is operated in this state and the front wheel is steered beyond a predetermined angle, the front wheel double speed lever is operated to increase the peripheral speed of the front wheel. There is a problem that the vehicle becomes unstable because the state changes rapidly.
In particular, a work vehicle such as Patent Document 3 is provided with a safety device that restricts sliding of the auxiliary transmission lever to the high-speed position by the operation of the shift lock device when the front-wheel double-speed device is enabled. However, since the control means of the auxiliary transmission lever is an electric shift lock device, in a work vehicle in which the vehicle body is susceptible to vibration for use, such a safety device may cause a failure due to vibration.
Accordingly, an object of the present invention is to improve the safety by allowing the front wheel speed increasing control member to regulate the sliding of the front wheel speed increasing operation member when the sub-shift is at a high speed, thereby enabling stable, smooth and quick turning. A work vehicle is provided.

  Therefore, according to the first aspect of the present invention, there is provided a sub-transmission shaft that transmits rotational power from the engine via the main shaft and the main transmission shaft, and is capable of shifting by operation of the sub-transmission operation member, and rotation of the sub-transmission shaft. According to the steering angle of the front wheel when the vehicle is driven in the front-rear wheel drive state by operating the front-wheel drive output shaft that transmits power to the front wheels and the front-wheel acceleration operation member provided on the front-wheel drive output shaft. In a work vehicle comprising a front wheel acceleration drive switching mechanism for increasing the peripheral speed of the front wheel, the auxiliary transmission operation member is linked to the auxiliary transmission operation member between the auxiliary transmission operation member and the front wheel acceleration operation member. A front wheel speed increasing check mechanism including a front wheel speed increasing check member that restricts sliding of the front wheel speed increasing operation member via a link member is provided.

  According to a second aspect of the present invention, in the work vehicle according to the first aspect, the front wheel speed increasing check member is an elastic member that pulls in a direction in which the front wheel speed increasing operation member is moved away from the turning track to the position where the front wheel speed increasing operation member is placed. It is characterized by providing.

  According to a third aspect of the present invention, in the work vehicle according to the first aspect, the front wheel speed increasing check member is rotatably provided by the link member, and is accompanied by a high speed position of the auxiliary transmission operation member. The front wheel speed increasing operation member is brought into contact with the front wheel speed increasing operation member on a rotation trajectory to a position where the front wheel speed increasing operation member is moved to prevent the front wheel speed increasing operation member from rotating.

  According to the first aspect of the present invention, the sub-transmission shaft that transmits the rotational power from the engine via the main shaft and the main transmission shaft and can shift by operating the sub-transmission operation member, and the rotational power of the sub-transmission shaft The front wheel drive output shaft that transmits to the front wheels and the front wheel acceleration operation member provided on the front wheel drive output shaft, the vehicle is driven in the front and rear wheel drive state according to the steering angle of the front wheels. In a work vehicle including a front wheel acceleration drive switching mechanism for increasing the peripheral speed, a front wheel increase is provided between the auxiliary transmission operation member and the front wheel acceleration operation member via a link member linked to the auxiliary transmission operation member. Since the front wheel speed increasing check mechanism including the front wheel speed increasing checking member that restricts the sliding of the speed operating member is provided, the position of the front wheel speed increasing checking member is determined by the rotational speed of the sub transmission shaft corresponding to the gear position of the sub speed operating member. And the sub-shift operating member is in the low speed position. In this case, the front wheel speed increasing operation member can be slid between the on / off positions, and when the auxiliary speed change operating member is positioned at the high speed stage, the auxiliary speed change operating member is operated via the link member. Thus, the front wheel speed increasing check member can be moved to restrict the sliding of the front wheel speed increasing operation member to the ON position. Accordingly, it is possible to provide a work vehicle with improved safety that can be turned stably, smoothly and quickly.

  According to the second aspect of the present invention, the front wheel speed increasing check member is provided with the elastic member that pulls in the direction away from the turning track to the position where the front wheel speed increasing operation member enters, so that the sub-speed change operation member has a low speed. In the step position, sliding of the front wheel speed increasing operation member by the front wheel speed increasing check member is not hindered, and the front wheel speed increasing operation member can be slid between the on / off positions. Therefore, it is possible to provide a work vehicle with improved safety that can be turned stably, smoothly and quickly with a simple configuration.

  According to the third aspect of the present invention, the front wheel speed increasing check member is provided so as to be rotatable by the link member, and the front wheel speed increasing operation member is rotated to the entrance position in accordance with the high speed position of the auxiliary speed change operation member. Since the front wheel acceleration operating member is brought into contact with the front wheel speed increasing operation member on the moving track to prevent the front wheel speed increasing operating member from rotating, the front wheel speed increasing operating member is prevented from rotating by the front wheel speed increasing check member at the auxiliary speed high speed stage. Thus, the front wheel acceleration operating member cannot slide to the on position, the front wheel acceleration drive switching mechanism can be prevented from accelerating the front wheel, and the vehicle can be prevented from changing suddenly during high-speed traveling. it can. Therefore, it is possible to provide a work vehicle with improved safety that can be turned stably, smoothly and quickly with a simple configuration.

It is a left view of a wheel type tractor as an agricultural work vehicle concerning one example of the present invention. It is a cross-sectional development view of a mission case. FIG. 6 is a perspective view of the vicinity of the left side of the driver's seat showing the installation positions of the auxiliary transmission operation member and the front wheel acceleration operation member. It is a whole perspective view of a front wheel speed increase check mechanism. FIG. 5 is a perspective view of the vicinity of a front wheel speed increasing operation member showing a position of a front wheel speed increasing check member at a sub-speed low speed stage. FIG. 6 is a perspective view of the vicinity of a front wheel speed increasing operation member showing a position of a front wheel speed increasing check member at a sub-speed high speed stage.

Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.
FIG. 1 shows a side view of a wheeled tractor as an example of the present invention. The tractor 1 of this example includes a front wheel 3 and a rear wheel 4 before and after a vehicle body frame 2, a bonnet 5 is formed above the front wheel 3, and an engine 40 as a prime mover portion and a clutch at a rear portion of the engine 40 inside A housing 41 is disposed.

  Further, a transmission case 42 is disposed at the rear of the clutch housing 41, and power from the engine 40 is transmitted to the front wheels 3 and the rear wheels 4. And the control part 7 is provided in the rear part of the bonnet 5 continuously.

  In the control unit 7, an operation pedal (not shown) such as an accelerator pedal and a clutch pedal as a vehicle operation unit, a steering handle 8, a driver's seat 11, and the like are provided. Further, below the control unit 7, an elevating step 10 for an operator to get on and off the control unit 7 is attached.

  The power from the engine 40 is transmitted to the PTO shaft 38 protruding from the rear end of the transmission case 42, and the PTO shaft 38 is connected to the rear end of the vehicle via a universal joint, a work implement mounting device 39, etc. (not shown). The illustrated working machine is driven.

  Next, the configuration of power transmission will be described. FIG. 2 is a developed sectional view of the mission case. First, power from the engine 40 is transmitted from the gear 44 of the input shaft 43 in the mission case 42 to the PTO shaft 46 via the gear 47 of the PTO output shaft 45. The PTO output shaft 45 is provided on the same axis as the PTO shaft 46 that extends rearward of the vehicle and drives the work implement s.

  Further, the other from the gear 44 of the input shaft 43 is transmitted to the main transmission shaft 61 via the gear 62 of the main transmission shaft 61. Further, main transmission shifters 73 and 78 linked to a main transmission lever (not shown) in the control unit 27 are spline-fitted to the auxiliary transmission shaft 76 below the main transmission shaft 61 so as to be slidable in the axial direction. The Main transmission shifters 73 and 78 are integrally formed.

  Accordingly, the operator operates the main transmission lever to select the main transmission shifter 78 and the gear 77 provided on the main transmission shaft 61, thereby setting the main transmission to the low speed stage (L). In addition, the main shift can be set to the high speed (H) by selecting the main shift shifter 73 and the gear 62 to be engaged.

  Further, by selecting the main transmission shifter 78 and the gear 79 provided on the main transmission shaft 61, the gear 80 provided on the auxiliary transmission shaft 76 is reversely rotated via the gear 52 of the PTO output shaft 45 ( R). When the main transmission shifters 73 and 78 do not mesh with any gear, the neutral is set.

  Next, the auxiliary transmission shaft 76 is provided with auxiliary transmission shifters 81 and 87 linked to an auxiliary transmission operating member 8 (sub transmission lever), which will be described later, provided in the control unit 27, by spline fitting so as to be slidable in the axial direction. It is done.

  Accordingly, when the operator operates the auxiliary transmission operation member 8 to select the auxiliary transmission shifter 81 and the gear 82 provided on the main transmission shaft 61, the auxiliary transmission 1st speed, the auxiliary transmission shifter 81, By selecting the gear 83 provided on the main transmission shaft 61 to be engaged and selecting the second speed of the auxiliary transmission, the auxiliary transmission shifter 87 and the gear 63 provided on the main transmission shaft 61 are selected and selected, the third speed of the auxiliary transmission ( Sub-shift high-speed stage), and the sub-shift shifter 87 and the gear 84 provided on the sub-transmission shaft 76 are engaged and selected as sub-speed 4 (sub-speed high speed stage). 76 is rotated.

  By selecting the gear meshing by sliding of the auxiliary transmission shifter 78, the rotation of the main transmission shaft 61 is output through three speeds, and the rotational power input to the auxiliary transmission shaft 76 is provided in the auxiliary transmission shaft 76. Is output to the rear wheel drive system by the gear 86 or the like.

  The front wheel drive output shaft 85 is provided with a front wheel acceleration drive switching mechanism 88, and the rotational power input from the auxiliary transmission shaft 76 to the front wheel drive output shaft 85 is passed through the front wheel drive output shaft 85. Then, it is inputted to a differential device (not shown) on the front wheel side which is a front wheel drive system, and the front wheels 3 are driven via an axle or the like in a front axle case (not shown).

  The front wheel acceleration drive switching mechanism 88 includes a dog clutch 88h, a multi-plate clutch 88i, a transmission shaft 88j, and the like. The dog clutch 88h and the multi-plate clutch 88i are front wheel accelerations such as a front wheel acceleration lever described later. The operation member 9 is linked.

  Accordingly, when the front wheel speed increasing operation member 9 is turned to the on (on) position, the dog clutch 88h is turned off and the multi-plate clutch 88i is turned on. Is transmitted to the front wheel 3 from the front wheel drive output shaft 85 by being increased by the transmission shaft 88j to a speed approximately twice that of the rotation of the front wheel drive output shaft 85 and returning to the front portion of the front wheel drive output shaft 85. Is done.

  On the other hand, when the front wheel speed increasing operation member 9 is turned to the off (off) position, the dog clutch 88h is turned on and the multi-plate clutch 88i is turned off. Is transmitted to the front wheel 3 through the front wheel drive output shaft 85 at the same rotational speed. In addition, since these structures are the well-known techniques shown, for example in Unexamined-Japanese-Patent No. 2004-98873, detailed description is abbreviate | omitted.

  Next, the linkage of the auxiliary transmission operation member and the front wheel acceleration operation member by the front wheel acceleration suppression member, which is a feature of the present invention, will be described in detail. 3 is a perspective view of the vicinity of the left side of the driver's seat showing the installation positions of the auxiliary speed change operation member and the front wheel speed increase operation member, FIG. 4 is an overall perspective view of the front wheel speed increase check mechanism, and FIG. FIG. 6 is a perspective view of the front wheel speed increasing operation member and its vicinity showing the position of the front wheel speed increasing operation member showing the position of the speed increasing check member, and FIG.

  First, as shown in FIG. 3, the rotation speed of the auxiliary transmission shaft 76 linked to the auxiliary transmission shifter 78 is changed from the lever guide 14 to the front part of the fender 12 disposed on the left side of the vehicle. A sub-transmission operation member 8 such as a sub-transmission lever for projecting is provided. The auxiliary speed change operation member 8 is not limited to the exemplified lever, and may be a member that can operate a front wheel speed increasing check mechanism 91 described later, such as a switch.

  Next, in front of the driver's seat 11 and at the rear of the floor 6, there is a front wheel speed increase lever such as a front wheel speed increasing lever linked to the front wheel speed increasing drive switching mechanism 88 that turns on / off the front wheel speed increasing operation. A speed operating member 9 is projected. The front wheel speed increasing operation member 9 is not limited to the exemplified lever, and may be any member that can operate a front wheel speed increasing check mechanism 91 described later, such as a switch.

  As shown in FIG. 4, a link mechanism 92 linked to the front wheel acceleration drive switching mechanism 88 is installed in front of the front wheel acceleration operation member 9, and the rear end portion of the link mechanism 92 is connected to the front wheel acceleration drive switching mechanism 88. The speed increasing operation member 9 is connected to a rotating shaft 9a at the lower part. Therefore, the front wheel speed increasing operation on / off operation by the front wheel speed increasing drive switching mechanism 88 'as described above is performed through the link mechanism 92 by the sliding operation of the front wheel speed increasing operating member 9.

  The link mechanism 92 links the front wheel speed increasing operation member 9, the dog clutch 88h of the front wheel speed increasing drive switching mechanism 88 ', and the multi-plate clutch 88i, and this front wheel speed increasing drive switching mechanism 88'. It is comprised from the board | plate member 92a linked | linked to this, the elastic member 92b, etc.

  When the front wheel speed increasing operation member 9 is in the rear off position, the front wheel speed increasing operation member 9 is moved by the locking member 92c provided in the notch in accordance with the biasing of the elastic member 92b. It is locked at the rotational position corresponding to the OFF position. Accordingly, a link member (not shown) linked to the on-board member 92a turns on the dog clutch 88h and turns off the multi-plate clutch 88i.

  When the front wheel speed increasing operation member 9 is rotated to the front ON position, the rear pulling force of the locking member 92c is released, so that the upper panel member 92a rotates about the rotation axis. As a result of the locking member 92c being locked at the notch position corresponding to the on position of the front wheel speed increasing operation member 9, the on-board member 92a is locked at the rotational position corresponding to the on position of the front wheel speed increasing operating member 9. Is done.

  Therefore, a link member (not shown) linked to the on-board member 92a turns off the dog clutch 88h and turns on the multi-plate clutch 88i. In FIG. 4, in order to explain the link mechanism 92 and the front wheel speed increasing check mechanism 93 to be described later, for the sake of convenience, the elevating step 10 provided on the left side of the vehicle body and the covering members in the vicinity of the elevating step 10 are removed. It is shown.

  Next, a front wheel speed increase check mechanism 93 that restricts the sliding of the front wheel speed increase operation member 9 is provided between the auxiliary speed change operation member 8 and the front wheel speed increase operation member 9. The front wheel speed increase check mechanism 93 includes a link member 94 such as a wire, a front wheel speed increase check member 95 as a stopper, and the like.

  A base end member 8 a having a round bar-like member 8 b at the tip is provided at the base end portion of the auxiliary transmission operation member 8. The base end member 8a is provided with a rotation fulcrum at a stay supported by the transmission case, and a lever 96 that rotates in the lateral direction of the vehicle body can be rotated. Parts are connected. The auxiliary transmission operation member 8 is linked to the auxiliary transmission shifter 78 in the mission case 42 and can be rotated to a predetermined position of the gear stage around the rotation shaft 8a below the auxiliary transmission operation member 8. This is a well-known technique.

  Next, on the front wheel acceleration operation side that is the on-position side of the front wheel acceleration operation member 9 (in front of the front wheel acceleration operation member 9), a front wheel acceleration suppression member 95 such as a substantially U-shape in plan view is provided. As shown in FIGS. 5 to 6, the vehicle is installed so as to be rotatable in the vehicle front-rear direction around a rotation shaft 95 b provided in the inner portion 95 a on the vehicle body side.

  Further, a spring or the like is provided between a hole 95d penetrating the center portion 95c of the front wheel speed increasing check member 95 and a stay 97 attached to the transmission case 42 in front of the front wheel speed increasing checking member 95. By interposing the elastic member 98, the front wheel speed increasing check member 95 is always pulled to the front side (vehicle front side) of the front wheel speed increasing operating member 9 by the biasing of the elastic member 98. .

  Further, the other end portion of the link member 94 is connected to an attachment portion 95f extending to the braking portion 95e of the front wheel speed increasing check member 95.

  Here, with regard to front wheel acceleration when the vehicle is turning, the auxiliary transmission shaft 76 is first set to a low speed state (including the 1st to 2nd speeds, the C speed, and the neutral position). When the vehicle is traveling at a low speed, as shown in FIGS. 6 to 7, the auxiliary transmission operation member 8 has a predetermined position in the lever groove at a position away from the transmission case 42. The end member 8a does not come into contact with the lever 96, and the lever 96 is not pressed toward the inner side of the machine body (in the direction of the mission case 42 in the drawing), so the lever 96 is not rotated.

  That is, since there is no traction action of the link member 94, the front wheel speed increasing check member 95 is pulled to the front side of the vehicle around the rotation shaft 95b by the urging of the elastic member 98. Even if 9 is rotated forward, the braking portion 95e of the front wheel acceleration control member 95 does not contact the lever front end portion 9a of the front wheel acceleration operation member 9 and does not hinder the rotation of the front wheel acceleration operation member 9. Since this is the state, the front wheel speed increasing operation member 9 can be turned to the ON position on the vehicle front side.

  Accordingly, at the low speed stage of the sub-shift where the vehicle traveling speed is relatively slow, the operator rotates the front wheel speed increasing operation member 9 to the ON position on the front side of the vehicle as the front wheel 3 is turned by the steering handle. Thus, by operating the front wheel acceleration drive switching mechanism 88 and increasing the peripheral speed of the front wheel 3 to double speed as described above, the vehicle can be turned smoothly and quickly while being stabilized.

  Next, as shown in FIG. 4 and FIG. 6, when the vehicle is running at high speed, which is the high speed state of the auxiliary transmission shaft 76 with the auxiliary transmission operation member 8 in the high speed (third speed or fourth speed) position. Since the auxiliary transmission operation member 8 is slid to a predetermined position in the lever groove near the transmission case 42, the base end member 8a of the auxiliary transmission operation member 8 moves the lever 96 in the direction toward the inner side of the body (the transmission case in the drawing). 42 direction) and rotate.

  Next, as the lever 96 rotates, the link member 94 is pulled (slid) toward the lever 96, so that the link member 94 urges the front wheel speed increasing check member 95 to bias the elastic member 98. Accordingly, the vehicle is rotated to the vehicle rear side (the rotation track side of the front wheel speed increasing operation member 9) around the rotation shaft 95b via the attachment portion 95f.

  At this time, since the braking portion 95e of the front wheel speed increasing check member 95 is positioned on the turning path to the on (on) position of the front wheel speed increasing operating member 9, the front wheel speed increasing operating member 9 is set to the front on position. Even if it is attempted to rotate, the lever front end portion 9a contacts the braking portion 95e, so that the front wheel speed increasing operation member 9 is prevented from rotating, so that the front wheel speed increasing operation member 9 is in front of the vehicle. The front wheel speed increasing operation member 9 is not turned to the speed operation on position, and the front wheel speed increasing operation member 9 is held at the front wheel speed increasing operation off position.

  Therefore, at the high speed stage of the sub-shift where the vehicle traveling speed is relatively fast, an operator may increase the front wheel speed increasing operation member 9 in order to accidentally increase the speed of the front wheel 3 as the front wheel 3 turns by the steering handle. Even if the front wheel speed increasing operation is to be turned to the ON position, the front wheel speed increasing operation member 9 is obstructed by the front wheel speed increasing checking member 95 and the front wheel speed increasing operation member 9 is prevented from rotating. Can do. For this reason, it is possible to prevent the front wheel 3 from being accelerated due to the operation of the front wheel acceleration drive switching mechanism 88, and to prevent a sudden change in the traveling state of the vehicle during high speed traveling.

  Note that when the above-described sub-shift of the vehicle is switched from the high speed stage to the low speed stage, the lever 96 is pulled by the rotation of the lever 96 accompanying the sliding operation of the sub-speed change operation member 8. As a result, the front wheel speed increasing check member 95 is rotated and returned to the front side of the vehicle by the urging of the elastic member 98, so that the front wheel speed increasing operation member 9 is prevented from rotating and the front wheel speed increasing member 9 is increased. The speed operating member 9 can be turned to the on position side of the front wheel speed increasing operation.

  As described above in detail, the work vehicle 1 of this example transmits the rotational power from the engine 40 via the main shaft 51 and the main transmission shaft 61, and allows the sub-transmission shaft to be shifted by operating the sub-transmission operation member 8. 76, the front wheel drive output shaft 85 that transmits the rotational power of the auxiliary transmission shaft 76 to the front wheels 3, and the front wheel speed increasing operation member 9 provided on the front wheel drive output shaft 85 in the front and rear wheel drive state. A front wheel acceleration drive switching mechanism 88 ′ that increases the peripheral speed of the front wheel 3 in accordance with the steering angle of the front wheel 3 during traveling of the vehicle, and the auxiliary transmission operation member 8, the front wheel acceleration operation member 9, A front wheel speed increase check mechanism 93 including a front wheel speed increase check member 95 that restricts sliding of the front wheel speed increase operation member 9 via a link member 94 linked to the auxiliary speed change operation member 8 is provided. .

  In the above-described example, the wheel type tractor has been described as an example of the work vehicle. However, the present invention is not limited to this, and the front wheel acceleration drive switching mechanism such as a construction work vehicle such as a wheel type bull tosa can be used. As long as the vehicle has

8 Sub-transmission operating member 8a Base end member 9 Front wheel speed increasing operating member 9a Lever front end portion 93 Front wheel speed increasing checking mechanism 94 Link member 95 Front wheel speed increasing checking member 95a Inner portion 95b Rotating shaft 95c Central portion 95d Hole portion 95e Braking portion 95f Mounting portion 96 Lever 98 Elastic member

Claims (3)

A sub-transmission shaft that transmits rotational power from the engine via the main shaft and the main transmission shaft, and is capable of shifting by operation of the sub-transmission operation member;
A front wheel drive output shaft for transmitting the rotational power of the auxiliary transmission shaft to the front wheels;
Front wheel acceleration that increases the peripheral speed of the front wheel according to the steering angle of the front wheel when the vehicle is traveling in the front and rear wheel drive state by operating a front wheel acceleration operation member provided on the front wheel drive output shaft A drive switching mechanism;
In a work vehicle comprising:
A front wheel speed increasing check member for restricting sliding of the front wheel speed increasing operation member is provided between the auxiliary speed shifting operation member and the front wheel speed increasing operation member via a link member linked to the sub speed shifting operation member. A work vehicle comprising a front wheel speed increasing check mechanism.   2. The work vehicle according to claim 1, wherein the front wheel speed increasing check member includes an elastic member that pulls in a direction away from a turning track to a position where the front wheel speed increasing operation member is moved.   The front wheel speed increasing check member is provided so as to be rotatable by the link member, and the front wheel speed increasing member is rotated on a rotation path to a position where the front wheel speed increasing operation member is moved in accordance with a high speed position of the auxiliary transmission operation member. The work vehicle according to claim 1, wherein the work vehicle is brought into contact with a speed operating member to prevent the front wheel speed increasing operation member from rotating.

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