JP2012116229A - Front wheel speed increasing device of working vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent operational failure of a speed increase switching motor by muddy water, and to further prevent damaging even if a speed increasing mechanism causes the operational failure by mud, by making it difficult to stick an earth mass and muddy water to the speed increase switching motor for operating the speed increasing mechanism.SOLUTION: This front wheel speed increase device of a working vehicle is characterized in that a front axle housing 60 is supported by belt iron-like right-left side frames 80R and 80L arranged on the right and left, and the speed increase switching motor 82 is arranged on the front side of the front axle housing 60 and on a support base 81 sandwiched by the right-left side frames 80R and 80L, and a speed increase switching shaft 70 for operating the speed increasing mechanism 105 for increasing a speed of right-left front wheels 6 and 6 and an output shaft of the speed increase switching motor 82 are connected by a tension spring 99, and the speed increase switching shaft 70 is switched to a front wheel speed increase by pulling the tension spring 99 by driving of the speed increase switching motor 82 in the speed increase switching shaft 70 energized to and held by a clutch disengaging position.

Description

  The present invention relates to a front wheel speed increasing device for a work vehicle such as a tractor or a lawn mower.

In a work vehicle having a traveling device composed of four wheels, left and right front wheels and left and right rear wheels, a front wheel speed increasing device is provided to make a sharp turn by driving the peripheral speed of the front wheel faster than the peripheral speed of the rear wheel when turning.
For example, in a front wheel speed increasing device for a work vehicle described in Japanese Patent Application Laid-Open No. 2007-45177, a transmission case that constitutes a vehicle body is disposed between a front wheel and a rear wheel, and a front wheel speed increasing device is disposed on a side surface of the transmission case. The front wheel speed increasing rate of the front wheel speed increasing device is changed and controlled by an electric motor.

JP 2007-45177 A

  Since the conventional front wheel speed increasing device of the work vehicle is arranged near the rear wheel, it is easy for dirt, muddy water, etc. to come and adhere from the tilling device mounted on the rear part of the machine body, and the electric motor and speed increasing operation mechanism May malfunction.

  For this reason, in the present invention, it is made difficult for dirt or muddy water to adhere to the speed increasing switching motor that operates the speed increasing mechanism, thereby preventing malfunction of the speed increasing switching motor due to muddy water. It is an object to prevent damage even if it becomes inoperable due to mud.

The problems of the present invention are solved by the following technical means.
According to the first aspect of the present invention, the front axle housing 60 is supported by the left and right side iron-shaped side frames 80L and 80R provided on the left and right sides, and is sandwiched between the left and right side frames 80L and 80R on the front side of the front axle housing 60. The speed increasing switching motor 82 is disposed on the support base 81, and the speed increasing switching shaft 70 for operating the speed increasing mechanism 105 for increasing the speed of the left and right front wheels 6 and 6 and the output shaft of the speed increasing switching motor 82 are pulled. The acceleration switching shaft 70 connected by the spring 99 and biased and held at the clutch disengagement position is driven by the acceleration switching motor 82 so that the tension spring 99 is pulled to switch the acceleration switching shaft 70 to the front wheel acceleration. The feature is a front wheel speed increasing device for a working vehicle.

  With this configuration, muddy water splashing from the rear rear wheel and work machine with respect to the speed increasing switching motor 82 is prevented by the front axle housing 60, and muddy water splashing from the left and right and the bottom is prevented by the left and right side frames 80R and 80L and the support base 81. Since the acceleration of the front wheel 6 is pulled by the rotational driving force of the speed increasing switching motor 82 and the tension spring 99 is pulled to switch the speed increasing switching shaft 70 to speed increasing, the speed increasing switching shaft 70 may be fixed with mud. However, the extension spring 99 is prevented from extending and the speed increasing switching motor 82 and the connecting structure are prevented from being damaged.

  The invention according to claim 2 is characterized in that a motor stop sensor 104 for detecting the operation of the speed increasing switching motor 82 is provided at a connecting portion between the speed increasing switching shaft 70 and the output shaft of the speed increasing switching motor 82. The front wheel speed increasing device for the work vehicle according to Item 1 is provided.

With this configuration, in addition to the operation of the first aspect, the rotation of the acceleration switching shaft 70 is reliably detected by the motor stop sensor 104 provided with the acceleration switching operation near the acceleration switching shaft 70.
According to a third aspect of the present invention, the connecting portion between the speed increasing switching shaft 70 and the speed increasing switching motor 82 is provided close to the swing shaft 11 of the pivot case 62. It was set as the front-wheel speed increase apparatus of the described working vehicle.

  With this configuration, in addition to the operation of the first aspect, even if the front axle housing 60 swings left and right, the relative position change between the acceleration switching shaft 70 and the output shaft of the acceleration switching motor 82 is small, and the acceleration switching is performed. Operates without any problem.

  According to the invention of claim 1 or claim 2 or claim 3, the speed increasing switching motor 82 is prevented from being hit by muddy water scattered from the rear part of the machine body, and the speed increasing switching motor 82 is effectively damaged due to electric leakage. Even if the speed increasing switching shaft 70 or the connecting portion between the speed increasing switching shaft 70 and the speed increasing switching motor 82 is fixed by mud, the speed increasing switching motor 82 is forcibly driven. The tensile force 99 absorbs the driving force to prevent the connecting portion and the speed increasing switching shaft 70 from being damaged.

It is a whole side view of an Example work vehicle (tractor). It is a whole top view of an Example working vehicle. It is side sectional drawing of the mission case of an Example working vehicle. It is a plane sectional view of the speed increasing case. It is a partially expanded side view of a speed increasing case. It is an enlarged plan view of a front axle housing showing a first embodiment of operation of the speed increasing switching shaft. It is a top view of the front axle housing which shows the operation | movement 2nd Example of an acceleration switching shaft. It is a rear view of a front axle housing. It is a side view of a front axle housing. It is a top view of the front axle housing which shows the operation | movement 2nd Example of an acceleration switching shaft. It is a sectional side view which shows a part of interlocking | linkage part of an acceleration switching motor and an acceleration switching shaft. It is an expanded side sectional view of a part in the mid case of the transmission case. It is an expansion side sectional view of an engine side case. It is an expansion perspective view of the guide body attached to the acceleration switching motor. (A), (b), (c) It is a top view which shows the operating state of a guide body. It is a side view which shows the support stand of an acceleration switching motor. It is side sectional drawing which shows the support structure of a radiator. It is a side view which shows attachment of an exhaust muffler. It is a front view which shows attachment of an exhaust muffler. It is a front view which shows the cross section of an exhaust muffler. It is a front view of the Example which provided the mounting support stand of the fuel poly tank. It is a front view of another Example of a mounting support stand.

Embodiments of the present invention will be described below based on the embodiments shown in the drawings.
1 and 2 are general views of a tractor shown as an example of a working vehicle in the present invention. The power of an engine 2 mounted in a bonnet 1 at the front of the airframe is appropriately shifted in a transmission case 3 before A front wheel is driven by a steering handle 8 which is transmitted to the wheel shaft 4 and the rear wheel shaft 5 to drive both the front wheel 6 and the rear wheel 7 or only the rear wheel 7 and an operator sitting on a seat 10 provided on the fuselage stands in the center. Run while steering No. 6. A work machine such as a rotary cultivator is mounted on the hitch 9 protruding rearward of the machine body, and the work machine mounted on the hitch 9 is driven by the rear PTO shaft 11 protruding rearward from the mission case 3. A working machine such as a lawn mower mounted between the front wheel 6 and the rear wheel 7 is driven by a mid PTO shaft 12 protruding forward from the rear part.

  FIG. 3 is a cross-sectional view of the power transmission mechanism. A main output shaft 18 protruding rearward from the engine side case 13 and an input shaft 20 protruding forward from the transmission case 3 are connected by a joint 19, and the upper side is connected by a connecting cover 21. Covering.

  Inside the engine side case 13, the power of the engine 2 is transmitted to the first output shaft 15 so as to be intermittently connected by the main clutch 14, and is slightly decelerated by the first gear 16 and the second gear 17 and transmitted to the main output shaft 18. ing.

  FIG. 13 shows another embodiment of the engine side case 13. An oil jumping gear 142 is pivotally supported next to the second gear 17 of the main output shaft 18, and an oil guide protrusion 140 is provided in the engine side case 13 on the upper side. The oil that is raised by the oil raising gear 142 is guided to the oil hole 16a provided at the center of the first gear 16 and is lubricated by flowing to the second gear 17 through the oil seal 141.

The mission case 3 is configured by integrally connecting three hollow cases of a front case 36, a mid case 37, and a rear case 45 from the front.
In the front case 36, the rotation of the input shaft 20 is transmitted to the first transmission shaft 25 by the third gear 22 and the fourth gear 23.

  In the mid case 37, the rotation of the first transmission shaft 25 is directly transmitted to the PTO transmission shaft 41 by the second joint 40, and further, the first transmission gear 27 and the second transmission gear 29 fixed to the first transmission shaft 25. A fourth transmission gear 26, a fifth transmission gear 28, a sixth transmission gear 30, and a reverse gear 50 (the reverse gear 50 is a gear not shown in the figure and is a first transmission gear) fitted to a travel shaft 24 with which the third transmission gear 31 is engaged. 27 is engaged with the shaft by the key shift clutch 46, and is shifted from the first speed to the third speed and reversely rotated to be transmitted to the traveling shaft 24.

  As shown in FIG. 12, the key shift clutch 46 pivotally supports two shift keys 129 and 130 in a key groove formed on the travel shaft 24, and large and small compression springs 133 and 134 are provided inside the open side of the shift keys 129 and 130. Intervene. The small compression spring 133 has a smaller diameter and is shorter than the large compression spring 134. When the gear key groove is slid, the large compression spring 134 firstly opens the key shift clutch 46 and easily slides, and eventually the small compression spring 133 acts. It does not come off the keyway.

  The rotation of the travel shaft 24 is transmitted to the large gear portion 59 of the gear cylinder 69 loosely fitted to the first transmission shaft 25 by the fourteenth gear 57, and the high and low clutch gear 32 that is spline-fitted to the bevel gear shaft 121 is the fourteenth. By meshing with the gear 57 or meshing with the small gear portion 68 of the gear cylinder 69, the bevel gear shaft 121 is shifted at a high and low speed, and the rotation of the bevel gear shaft 121 is transmitted to the rear wheel shaft 5 by the bevel gear 38 and the axle bevel gear 39. Further, the fifteenth gear 122, the fifth gear 33 and the clutch gear 34 which are spline fitted to the bevel gear shaft 121 are transmitted to the front wheel drive shaft 35, and the rotation of the front wheel drive shaft 35 is shown in FIG. The second front wheel drive shaft 101 is transmitted.

The rotation of the PTO transmission shaft 41 is transmitted to the transmission portions of the rear PTO shaft 11 and the mid PTO shaft 12 provided on the rear side of the rear wheel shaft 5.
The tenth gear 55 is spline-fitted to the PTO transmission shaft 41 and the first counter gear 42 is loosely fitted, and the eleventh gear 48 is spline-fitted to the rear PTO shaft 11 and the first clutch gear 56 is loosely fitted. The PTO clutch gear 43 is loosely fitted to the first clutch gear 56, and the twelfth gear 58 is splined. A constant mesh clutch switching gear 47 that is always meshed with the eleventh gear 48 and meshed appropriately with the first clutch gear 56 and the PTO clutch gear 43 is externally fitted. The second clutch gear 43, the eleventh gear 48, and the clutch switching gear 47 constitute a PTO clutch 150, and the PTO clutch 150 is shifted by a single PTO switching lever 149 provided near the seat 10.

  The first counter gear 42 rotates through the second counter gear 49 of the first counter shaft 50, the third counter gear 44 of the second counter shaft 51, and the fourth counter gear 52 of the third counter shaft 53. The mid PTO shaft 12 is driven by being transmitted to a thirteenth gear 54 formed on the motor 12.

  FIG. 4 is a cross-sectional view of the front axle housing 60. A speed increasing case 61 is attached to the rear side of the front axle housing 60 with a bolt 77, and the front axle housing 60 and the speed increasing case 61 are integrated into a front pivot case 96 and a rear pivot. It is supported by a case 62 so that it can swing left and right. By integrating the front axle housing 60 and the speed increasing case 61, the weight can be reduced and the front / rear balance of the entire tractor is improved.

  The power from the front wheel drive shaft 35 described with reference to FIG. 3 is input to the second front wheel drive shaft 101 that is pivotally supported on the rear pivot case 62 side of the speed increasing case 61. A first speed increasing gear 63 is formed in the speed increasing case 61, and a first clutch 66 that is spline-fitted to the front bevel shaft 78 is engaged with a clutch pawl 63 a formed on the end face of the first speed increasing gear 63 by a clutch spring 67. The second front wheel drive shaft 101 is pressed and engaged to transmit the rotation of the second front wheel drive shaft 101 to the front wheel bevel shaft 78 (constant speed four-wheel drive).

The small front bevel gear 74 of the front wheel bevel shaft 78 and the large front bevel gear 75 in the front axle housing 60 are engaged with each other to rotate the differential gear set 76 to drive the front wheel drive shafts 4R and 4L.
The speed increasing mechanism 105 in the speed increasing case 61 supports the speed increasing shaft 64 in parallel with the front wheel bevel shaft 78, and the second speed increasing gear 65 that meshes with the first speed increasing gear 63 is spline-fitted, and is wet. The clutch 71 is mounted, and the clutch gear 72 of the wet clutch 71 is meshed with a third speed increasing gear 73 that is spline-fitted to the front wheel bevel shaft 78. A clutch pressing ring 102 is fitted to the speed increasing shaft 64 between the second speed increasing gear 65 and the wet clutch 71, and a clutch switching plate 103 for engaging both the clutch pressing ring 102 and the first clutch 66 is provided. An acceleration switching shaft 70 for moving the clutch switching plate 103 is provided. The clutch switching plate 103 is supported by the guide pin 91 so as to be slidable in the axial direction of the speed increasing shaft 64 (FIG. 5). That is, when the acceleration switching shaft 70 rotates, the clutch pressing ring 102 moves in the direction of the wet clutch 71 via the clutch switching plate 103, and the clutch pawl 63a of the first clutch 66 is turned off. Thereafter, the clutch pressing ring 102 comes into contact with the wet clutch 71 to bring the wet clutch 71 into an engaged state. As a result, from the constant-speed four-wheel drive, the speed-up four-wheel drive in which the front wheels are accelerated is changed.

  When the speed increasing switching shaft 70 is rotated by the speed increasing switching motor 82, the speed increasing mechanism 105 disengages the first clutch 66 from the first speed increasing gear 63 and cuts off the rotation transmission of the front bevel shaft 78, and the clutch pressing ring. 102 pushes the wet clutch 71 to transmit the rotation of the speed increasing shaft 64 from the clutch gear 72 to the third speed increasing gear 73 to drive the front wheel bevel shaft 78 at a higher speed, and the front wheels 6 and 6 are driven at a higher speed. .

  The front wheel bevel shaft 78 is provided with a first lubricating hole 97 that passes through the center of the shaft, and the speed increasing shaft 64 is provided with a second lubricating hole 98 that supplies oil to the wet clutch 71, thereby improving the lubricity of the speed increasing mechanism. Cooling is improved.

  As shown in FIG. 6, the speed increasing switching shaft 70 protrudes upward from the speed increasing case 61, and a cam shaft arm 92 is fixed to the shaft end of the protruding speed increasing switching shaft 70, and the speed increasing speed is increased on the cam shaft arm 92. The inner wire of the speed increasing / disconnecting wire 95 connected to the switching motor 82 is connected via a tension spring 99. The outer wire of the speed increasing on / off wire 95 is attached to a wire attaching plate 94 attached to the boss portion 93 of the speed increasing case 61. By pressing the clutch pressing ring 102 against the wet clutch 71 with the tensile force of the tension spring 99, even if the wet clutch 71 is worn, the pressing force continues and is transmitted as a clutch engaged state.

FIG. 7 shows a configuration in which the front axle housing 60 is attached to the tractor body.
A front axle housing 60 is attached to left and right side frames 80L and 80R provided in the front-rear direction of the tractor body, and a plate-like support base 81 is attached between the left and right side frames 80L and 80R on the front upper side of the front axle housing 60. A speed increasing switching motor 82 is mounted on a table 81, and the rotation of the speed increasing switching motor 82 is transmitted to the speed increasing switching shaft 70 through a gear speed reducing mechanism 84, a rod 83 and a tension spring 99, thereby increasing the front wheel speed increasing speed. The clutch can be switched. The speed increasing / disconnecting wire 95 of FIG. 6 described above is configured to connect the speed increasing / disconnecting wire 95 to the gear reduction mechanism 84 instead of the rod 83. 7 to 9 show a configuration in which the speed increasing switching shaft 70 is rotated by the rod 83. FIG.

Next, the interlocking structure of the rod 83 and the acceleration switching shaft 70 will be described in detail.
Since the first plate 84b is fixed to the shaft 84a output from the gear reduction mechanism 84, when the shaft 84a rotates, the first plate 84b also rotates. The first rod 83 is loosely fitted to the first plate 84b, and when the first plate 84b rotates, the first rod 83 moves back and forth. Since these members are below the support base 81, they are indicated by dotted lines in FIG. 7, and the rear side of the first rod 83 extends to the rear of the support base 81 and is indicated by solid lines.

  The rear end of the first rod 83 is loosely fitted to the second plate 110. The second plate 110 is configured to rotate around a rotation fulcrum shaft 111 erected on the front axle housing 60. A second rod 112 is loosely fitted to the second plate 110, and a third plate 113 is loosely fitted to the other end of the second rod 112. A shaft 114 is connected to the third plate 113. The shaft 114 is configured to pass through the front axle housing 60 so as not to interfere with the steering cylinder 160. A fourth plate 115 is connected to the other end of the shaft 114, and a tension spring 99 is provided on the fourth plate 115, and the other end of the tension spring 99 is hung on the fifth plate 117. The speed increasing switching shaft 70 is connected to the fifth plate 117.

  Thereby, when the speed increase switching motor 82 rotates and the first rod 83 moves back and forth, the second plate 110 rotates about the rotation fulcrum shaft 111, and the second rod 112 moves in the left-right direction. The shaft 114 rotates through the third plate 113. When the shaft 114 rotates, the fourth rate 115 moves in the left-right direction, and the acceleration switching shaft 70 rotates through the fifth plate 117 via the tension spring 99.

When the driving of the acceleration switching motor 82 is stopped, the acceleration switching shaft 70 returns to the original position by the tension spring 99.
As shown in FIG. 11, a sensor pin 106 is provided at the tip of the third plate 113, and the movement of the sensor pin 106 contacts the sensor arm 105 of the motor stop sensor 104 to stop the rotation of the acceleration switching motor 82. Since the motor stop sensor 104 is provided near the acceleration switching shaft 70, the rotation of the acceleration switching shaft 70 is accurately detected.

  Although not shown, a wire connected to the governor of the engine 2 is provided on the first plate 84b so that the rotation of the engine 2 is reduced when the first plate 84b rotates, that is, when the front wheel speed increases.

  Note that the speed increasing switching motor 82 may be a motor with a built-in contact, and may stop after detecting two pulses and rotating 1.5 times. In this case, forward rotation is performed with the first two pulses and reverse rotation is performed with the next two pulses, but each is stored in the nonvolatile memory as a forward / reverse rotation signal, and the normality stored when the energization is resumed even if there is a sudden power failure. By reading and rotating the reverse rotation signal, the acceleration switching shaft 70 is normally rotated.

FIG. 10 is a diagram in which the members indicated by the dotted lines are omitted for easy viewing.
In the embodiment of FIG. 14, a guide body 125 provided with a first guide piece 126 and a second guide piece 127 is attached to the output shaft 124 of the speed increasing switching motor 82, and the first arc guide hole 126 a of the first guide piece 126 is attached. The throttle wire 130 connected to the governor of the engine 2 is engaged, and the rod 83 connected to the speed increasing switching motor 82 is engaged in the second arc guide hole 127a of the second guide piece 127. The rotation of the output shaft 124 detects the movement of the pin 128 protruding from the first guide piece 126 with the potentiometer 129.

  14A is a state in which the acceleration switching motor 82 is in the neutral position, FIG. 14B is a state in which the rod 83 is turned counterclockwise to push the rod 83 to increase the front wheel speed, and FIG. In this state, the rotation of the engine 2 is reduced.

  Further, the knuckle arms 86, 86 of the left and right front wheels 6, 6 are connected by a tie rod 87, and the left and right front wheels 6, 6 are steered by the operation of the steering cylinder 160. The front wheel break angle sensor 90 mounted on the support base 81 is rotated by the sensor plate 89 to detect the front wheel break angle.

A box-shaped protective cover 85 that covers the acceleration switching motor 82, the gear reduction mechanism 84, and the front wheel break angle sensor 90 is detachably mounted on the support base 81.
With this configuration, the speed increase switching motor 82, the gear reduction mechanism 84, and the front wheel break angle sensor 90 provided on the support base 81 are surrounded by the support base 81, the left and right side frames 80L and 80R, the front axle housing 60, and the protective cover 85. Therefore, malfunction due to adhesion of muddy water is eliminated.

In the above-described embodiment, the speed increasing mechanism 105 has been described by turning on and off the speed increasing clutch. However, a speed increasing mechanism that changes the rotational speed of the front wheels 6 may be used.
As shown in FIG. 16, the support base 81 is formed in a box shape and fixed with bolts 133 fitted into the first long hole 131 and the second long hole 132 formed in the side frame between the left and right side frames 80R and 80L. When the first long hole 131 on the front side is longer than the second long hole 132 on the rear side and the bolt 133 is loosened, the front cover descends as shown in the figure. When the butterfly bolt 134 is removed, the protective cover 85 can be removed. Maintenance of the internal speed increasing switching motor 82 and the like can be performed.

  FIG. 17 shows a support structure of the radiator 135. A lower portion of the radiator 135 is supported by the left and right side frames 80R and 80L by rubber mounts 137, an upper portion is connected to the engine 2 by a stay 138, and an inner surface of the bonnet 1 is formed on the upper portion of the radiator 135. An elastic heat insulating member 136 bonded to the hood 1 is provided to surround the engine room and to prevent the bonnet 1 from vibrating.

18 to 20 show the attachment configuration of the muffler 144. FIG.
An input pipe 144 a of the muffler 144 is connected to the exhaust manifold 146, and the exhaust pipe 144 b side is supported on the starter bracket 145 by an L-shaped bracket 148. The bracket 148 is provided with a large mounting hole, and is fitted to a bolt on the starter bracket 145 side so that the mounting position on the left, right, top and bottom can be adjusted.

  Further, the input pipe 144a is welded to the first partition plate 147a and the second partition plate 147b in the muffler 144, and the exhaust pipe 144b is welded firmly to the second partition plate 147b and the third partition plate 147c. Yes.

  FIG. 21 shows an embodiment in which a mounting table 153 on which a fuel plastic tank 154 for refueling a fuel tank is placed is provided on the side of the bonnet 1. 152 is attached by being screwed so that the vertical height can be changed and the horizontal rotation is possible.

Further, a cup holder 156 is provided laterally from the mounting table 153 so that the coffee cup 155 and the like can be inserted and held.
FIG. 21 shows a configuration in which the mounting movement table 153b is slidable on the hood 1 with respect to the mounting support table 153a. It is also possible to support the mounting support table 153a with a support column standing on the left and right sides of the bonnet 1 and make the mounting movement table 153b movable on the hood 1 in the entire left and right width.

6 Front Wheel 11 Swing Shaft 60 Front Axle Housing 62 Pivot Case 70 Speed Increase Switching Shaft 79 Motor Sensor 80L Left Side Frame 80R Right Side Frame 81 Support Base 82 Speed Increase Switching Motor 105 Speed Increase Mechanism 116 Tension Spring

Claims (3)

  The front axle housing (60) is supported by left and right band-like left and right side frames (80L) and (80R) provided on the left and right sides, and the left and right side frames (80L) and (80R) on the front side of the front axle housing (60). ) Between the speed change switching motor (82) and the speed change mechanism (105) for speeding up the left and right front wheels (6), (6). (70) and the output shaft of the speed increasing switching motor (82) are connected by a tension spring (99), and the speed increasing switching shaft (70) biased and held at the clutch disengaged position is driven by the speed increasing switching motor (82). A front wheel speed increasing device for a work vehicle characterized in that a tension spring (99) is pulled to switch the speed increasing switching shaft (70) to front wheel speed increasing.   The motor stop sensor (104) for detecting the operation of the speed increasing switching motor (82) is provided at a connecting portion between the speed increasing switching shaft (70) and the output shaft of the speed increasing switching motor (82). 2. A front wheel speed increasing device for a work vehicle according to 1.   The connecting portion between the speed increasing switching shaft (70) and the speed increasing switching motor (82) is provided close to the swing shaft (11) of the pivot case (62). Front wheel speed increasing device for work vehicles.

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