JPH08183465A - Steering system for working vehicle - Google Patents

Abstract

PURPOSE: To improve the reliability of constitution between a steering shaft and a Pitman arm and facilitate assembling/disassembling work so as to improve maintainability and reduce the number of part items in a steering system for a working vehicle. CONSTITUTION: A supporting frame 15 with a supporting part 55 is fixedly provided at a body frame 11, and a steering shaft 50 is insert-supported by the supporting part 5. A driving gear 51 thrust-supported by the upper face of the supporting part 55 is fitted to the steering shaft 50. A rotating shaft 53 thrust-supported by the upper face of the supporting part 55 and provided with a driven gear 52 fixed to the upper end so as to be meshed with the driving gear 51 is rotatably supported by the supporting part 55 and a bracket 65 fitted to the body frame 11. A Pitman arm 48 is fixed to a cylindrical Pitman arm shaft 66 insert-fitted out of relative rotation to the rotating shaft 53 below the bracket 65, and the Pitman arm shaft 66 is held between the bracket 65 and a supporting collar 70 fastened to the lower end of the rotating shaft 53.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a steering shaft having a steering handle attached to the upper end thereof, a drive gear mounted so as to be interlockable with the steering shaft, an axis line substantially parallel to the steering shaft, and a pitman arm. The present invention relates to a steering device for a work vehicle including a rotating shaft that is provided and a driven gear that meshes with the drive gear and is fixed to the rotating shaft.

[0002]

2. Description of the Related Art Conventionally, such a device is, for example,
It is already known from Japanese Patent Publication No. 36789.

[0003]

In such a steering device, it is necessary to reliably prevent the components such as the steering shaft, the rotary shaft, the drive gear and the driven gear from coming off. There is a demand to improve the maintainability and reduce the number of parts while avoiding complicated work. However, the above-mentioned related art does not disclose a configuration that meets such a demand.

The present invention has been made in view of the above circumstances, and enhances the reliability of the configuration between the steering shaft and the pitman arm, facilitates the assembly and disassembly work, improves the maintainability and reduces the number of parts. It is an object of the present invention to provide a steering device for a work vehicle designed to achieve the above.

[0005]

In order to achieve the above object, the invention according to claim 1 is a steering shaft having a steering handle attached to an upper end thereof, a drive gear movably attached to the steering shaft, and A steering device for a working vehicle, comprising: a rotating shaft having an axis substantially parallel to the steering shaft and having a pitman arm continuously provided; and a driven gear that meshes with the drive gear and is fixed to the rotating shaft. A drive frame is fixed to the vehicle body frame, the steering shaft is inserted into and supported by the support portion, and the drive gear is thrust supported on the upper surface of the support portion. The drive gear is attached to the steering shaft and thrust supported on the upper surface of the support portion. The rotating shaft with the driven gear that meshes with the drive gear fixed to the upper end rotates with the support and the bracket attached to the vehicle body frame. A pitman arm is fixedly mounted on a cylindrical pitman arm shaft that is supported in place and is inserted into the rotary shaft below the bracket so that relative rotation is impossible.The pitman arm shaft is attached to the bracket and the lower end of the rotary shaft. It is characterized in that it is sandwiched between a support collar to be fastened.

According to a second aspect of the present invention, in addition to the structure of the first aspect of the invention, the support frame has upper and lower support portions arranged above and below the vehicle body frame with a space therebetween. And a first bush attached to the first bracket having a first flange portion that engages from below with a first bracket detachably attached to the upper support portion, and an upper portion above the upper surface of the lower support portion. The steering shaft is rotatably supported by a second bush mounted on the lower support part and having a second flange part that engages with the drive gear and thrust-supports the drive gear. A plurality of caulking projections that engage with the lower surface of the section are provided at intervals in the circumferential direction,
A third bush that has a third flange portion that engages from above with the upper surface of the lower support portion and that is attached to the lower support portion; and a fourth bush that engages with the second bracket attached to the vehicle body frame from below.
The rotation shaft is rotatably supported by a fourth bush having a flange and mounted on the second bracket, and the driven gear is thrust supported by the upper surface of the third flange.

According to a third aspect of the present invention, in addition to the structure of the first or second aspect of the invention, the support frame includes a pair of side support portions fixed to both side portions of the vehicle body frame, respectively.
A frame body having a substantially U shape having an upper support portion connecting upper ends of the side support portions, and a lower support provided between the vehicle body frame and the upper support portion and between both side support portions. And a lower part of the steering shaft and an upper part of the rotary shaft are rotatably supported by the lower support part.

Further, in addition to the structure of the invention described in claim 1, 2 or 3, the invention described in claim 4 is such that the upper surface of the drive gear extends in the radial direction of the steering shaft and both ends are closed. A fitting groove is provided, and a pin penetrating the steering shaft along its radial direction is fitted into the fitting groove.

[0009]

According to the structure of the invention described in claim 1, the steering shaft is restricted from moving downward in the axial direction by the drive gear mounted on the steering shaft being thrust-supported by the upper surface of the support portion. In this state, it is rotatably supported by the support portion. Further, since the drive gear mounted on the steering shaft and the driven gear fixedly mounted on the rotating shaft are meshed with each other above the supporting portion, both gears do not drop downward, and the steering shaft and the rotating shaft Since the shaft is supported by the supporting portion, the distance between the steering shaft and the turning shaft can be accurately determined. Further, the downward movement of the rotary shaft is restricted by the driven gear fixed to the rotary shaft being thrust supported by the support portion, and the upward movement of the rotary shaft is relative to the rotary shaft. The impossible pitman arm shaft is regulated by being sandwiched between the support portion and the support collar.

Further, according to the structure of the invention described in claim 2, the steering shaft and the rotary shaft can be freely rotated by restricting the axial movement thereof with a simple structure using the first to fourth bushes. Can be supported by.

According to the configuration of the invention described in claim 3,
The upper support portion, the lower support portion and the both side support portions are arranged so as to surround the both gears so as to protect the drive gear and the driven gear from the surroundings.

Further, according to the structure of the invention described in claim 4, the relative rotation of the drive gear with respect to the steering shaft can be prevented and the drive gear can be prevented only by fitting the pin inserted through the steering shaft into the fitting groove. The axial movement of is restricted by the support portion of the support frame and the pin.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a riding lawn mower will be described below with reference to the drawings.

1 to 9 show an embodiment of the present invention. FIG. 1 is a side view of a riding lawn mower, FIG. 2 is a plan view of the riding lawn mower, and FIG. -3 line enlarged sectional view,
4 is an enlarged sectional view taken along line 4-4 of FIG. 3, and FIG. 5 is a sectional view taken along line 5-5 of FIG.
5 is a sectional view taken along line 6-6 of FIG. 5, FIG. 7 is a sectional view taken along line 7-7 of FIG. 5, FIG. 8 is a sectional view taken along line 8-8 of FIG. 5, and FIG. It is a 9-9 line expanded sectional view.

First, in FIGS. 1 and 2, a pair of front wheels W _F , W _F are operably suspended on the front portion of the vehicle body frame 11. On the other hand, a mission case 12 is fixed to the rear portion of the body frame 11, and rear axle housings 13 and 13 fixed to the left and right side surfaces of the mission case 12 allow the rear wheels W _R and W _R to rotate. Supported. Thus, the power input to the input shaft 14 protruding from the upper part of the mission case 12 is
It is transmitted to both rear wheels W _R , W _R via an internal speed change mechanism and a differential mechanism (not shown).

A vertical engine E is mounted on the front portion of the vehicle body frame 11. A support frame 15 is fixed to the vehicle body frame 11 on the rear side of the engine E, and a cover 16 having a column portion 16a that extends upward to cover the support frame 15 covers the vehicle body frame 11 on the upper rear side thereof. It is installed in this way. Thus, the passenger seat 1 is attached to the cover 16 at a position spaced backward from the column portion 16a.
7 are provided. Further, the engine E on the vehicle body frame 11 and the fuel tank 19 arranged on the support frame 15
Etc. are covered with a bonnet 18 connected to the body frame 11 so as to be able to jump forward.

Referring also to FIG. 3, the power from the crankshaft 20 having a substantially vertical axis and extending downward from the engine E is transmitted to the input shaft 14 of the transmission case 12 via the power transmission means 21. To be done. This power transmission means 21
Is a drive pulley 2 that is fixedly installed in the middle of the crankshaft 20.
2, a driven pulley 23 fixed to the input shaft 14, and a rear wheel power transmission endless belt 24 wound around the drive pulley 22 and the driven pulley 23. It is possible to switch between a state in which power is transmitted from the shaft 20 to the input shaft 14 and a state in which the tension state of the endless belt 24 is relaxed and power transmission is interrupted.

Both front wheels W _F , W _F and both rear wheels W _R , W _R
Below the body frame 11 between the cutter housing 2
5 is arranged, and the cutter housing 25 is supported by the vehicle body frame 11 so that it can be moved up and down by a link mechanism 26.

The cutter housing 25 is formed in a dish shape with the lower part open, and a pair of cutters 27 ₁ and 27 ₂ are rotatably accommodated in the cutter housing 25. Further, at both sides of the cutter housing 25, scalp rollers 28, 28 that roll on the ground to define the lowest limit position of the cutter housing 25 are pivotally supported.

The link mechanism 26 includes a pair of front links 29 connecting the front portion of the vehicle body frame 11 and the front portion of the cutter housing 25, and a pair of rear portions connecting the intermediate portion of the vehicle body frame 11 and the rear portion of the cutter housing 25. The passenger seat 1 has a link 30 and constitutes a so-called parallel link, and is connected to one of the two rear links 30 to be connected to the passenger seat 1.
By operating the raising / lowering operation lever 31 disposed on the left side of the cutter 7, the cutter housing 25 can be raised / lowered while keeping its posture with respect to the ground constant.

On the cutter housing 25, driven pulleys 33 ₁ and 3 coaxially connected to both cutters 27 ₁ and 27 ₂ are provided.
3 ₂ are arranged. On the other hand, a drive pulley 34 is fixedly installed on the crankshaft 22 of the engine E, and an endless belt 35 is wound around the drive pulley 34 and both driven pulleys 33 ₁ and 33 ₂ to form a winding transmission system 36. To be done.
Thus, the winding transmission system 36 responds to the rotational movement of the operating shaft 32 arranged vertically in the column portion 16a.
It is possible to switch between a clutch-on state in which the endless belt 35 is strained and a clutch-off state in which the strained state of the endless belt 35 is relaxed, and the operation lever 3 is provided on the upper end of the operation shaft 32.
7 is fixed.

By the way, the engine E is forcibly cooled by air, and the air after the engine E is cooled is the muffler storage chamber 3 formed under the front portion of the vehicle body frame 11.
Introduced in 8. A muffler 39 connected to the engine E is housed in the muffler housing chamber 38, and the air after engine cooling is used to cool the muffler 39. Further, a pair of pipe-shaped bumpers 40, 40 extending in the horizontal direction at intervals in the vertical direction are arranged at the front position of the muffler storage chamber 38.
0 and 40 are fixedly supported on the front end of the body frame 11.

On the rear side of the muffler 39 and below the vehicle body frame 11, a front axle frame 41 having a substantially U-shaped cross-section that opens downward forms a rear wall of the muffler housing chamber 38. Is fixed. A front axle beam 42 is inserted in the front axle frame 41, and the front axle beam 4 is
The central portion of the longitudinal direction 2 of the vehicle is swingable by a support shaft 43 having an axis extending in the longitudinal direction of the vehicle body frame 11, that is, the front-back direction of the riding lawn mower.
It is supported by 1.

At both ends of the front axle beam 42,
Axle 4 supporting the front wheels W _F , W _F and formed in a substantially L shape
5 and 45 are steerably supported respectively, and the axle 4
Knuckle arm 46,46 connected to the upper end of 5,45
The front ends of the tie rods 47, 47 are connected to each other.

With reference to FIGS. 4, 5, 6 and 7, the rear ends of the tie rods 47, 47 are commonly connected to a pitman arm 48 so that an occupant on the passenger seat 17 can handle the steering wheel 49. In response to the operation (see FIGS. 1 and 2), the steering angle operation amount of the steering handle 49 causes the pitman arm 48 to move through the steering shaft 50, the drive gear 51, the driven gear 52, and the turning shaft 53.
Is transmitted to

The body frame 11 is composed of a pair of vertical frame portions 11a, 11a which are parallel to each other and extend in the front-rear direction, and the upper ends thereof are coupled by a coupling portion 11b. The body frame 11 has a coupling portion 11b. The support frame 15 is attached so as to cover the above from above. Thus, the support frame 15
Are both vertical frame portions 11a of the vehicle body frame 11,
A substantially U-shaped frame 54 in which upper ends of a pair of side support parts 54a, 54a fixed to the outer surface of 11a are connected by an upper support part 54b, a connecting part 11b of the body frame 11, and an upper part. Both side support portions 54 are provided between the support portions 54b.
and a lower support part 55 provided between a and 54a.

The steering shaft 50 has an upper support portion 54b.
A first bush 57 that is detachably attached to the upper surface of the first bracket 56 from below, and a lower support portion 55.
The second bush 58 is engaged with the upper surface of the above from above. The upper support portion 54b is provided with a hole 59 through which the steering shaft 50 is inserted, and the first bracket 56 is formed.
Is detachably attached to the upper surface of the upper support portion 54b so as to straddle the portion provided with the hole 59 from above. The first bush 57 is a first bush that extends outward in the radial direction.
It has a flange 57a at the lower end and is formed in a cylindrical shape, and is inserted and attached to the first bracket 56 so as to prevent rotation around the axis, and the first flange 57a is inserted from the bottom to the first. The bracket 56 is engaged. Further, the second bush 58 is formed in a cylindrical shape having a second flange portion 58a protruding outward in the radial direction at the upper end, and as shown in FIG. 8, rotation about the axis is prevented. In this way, the lower support portion 55 is inserted and mounted, and the second collar portion 58a is engaged with the lower support portion 55 from above.

Caulking protrusions 60 ... Engaging with the lower surface of the first flange 57a are provided at a plurality of positions spaced apart in the circumferential direction of the steering shaft 50. The drive gear 51 is the second
The drive gear 51 is thrust-supported by the upper surface of the flange portion 58a, and the drive groove 51 has a surface opposite to the lower support portion 55. The fitting groove 61 extends in the radial direction of the steering shaft 50 and has both ends closed. Is provided, and a pin 62 penetrating the steering shaft 50 along its radial direction is fitted into the fitting groove 61.

The rotating shaft 53 has an axis substantially parallel to the steering shaft 50, and is engaged with the upper surface of the lower support 55 from above by a third bush 63 and a second bracket 65 attached to the vehicle body frame 11. Is inserted into the fourth bush 64 which is engaged from below. The third bush 63 is formed in a cylindrical shape having a third flange portion 63a protruding outward in the radial direction at the upper end, and is provided on the lower support portion 55 so as to prevent rotation about the axis. It is inserted and mounted, and the third flange portion 63a is engaged with the lower support portion 55 from above. Further, the second bracket 65 is connected to the connecting portion 11b of the vehicle body frame 11.
Is attached to the upper surface of the connecting portion 11b so as to fit into the opening 87 provided in
The bush 64 has a fourth flange portion 64 that extends outward in the radial direction.
It is formed into a cylindrical shape having a at the lower end and is inserted and attached to the second bracket 65 so as to prevent rotation around the axis line, and the fourth flange portion 64a is engaged with the second bracket 65 from below. To be done.

The driven gear 52 is a sector gear, is fixed to the upper end of the rotary shaft 53 by welding, and has a third bush 63.
Is thrust-supported on the third collar portion 63a.

Referring also to FIG. 9, the fourth bush 64
Below this, the rotary shaft 53 is coaxially surrounded and bent by a cylindrical pitman arm shaft 66, and the pitman arm 48 is fixed to the pitman arm shaft 66. Moreover, the rotating shaft 53
A groove 67, 68 extending in the axial direction is provided corresponding to each other on the outer surface of and the inner surface of the pitman arm shaft 66, and a key 69 is fitted into these groove 67, 68. Therefore, the pitman arm shaft 66 is inserted into the rotary shaft 53 so that the pitman arm shaft 66 cannot rotate relative to the rotary shaft 53.
A support collar 70 that contacts the lower end of the pitman arm shaft 66 is fastened to the lower end of the rotating shaft 53 with a bolt 71. The pitman arm shaft 66 includes a lower surface of the fourth flange portion 64a and a support flange 70. Will be sandwiched between.

Both side support portions 54a, 54a of the frame 54 of the support frame 15 are extended below the vehicle body frame 11, and these side support portions 54a, 54 are provided.
A stopper 72 for restricting the upper limit position of the cutter housing 25 is fixed to the lower end of a. That is, the stopper 72 is arranged horizontally corresponding to the entire width of the vehicle body frame 11 and a pair of mounting plate portions 72b which are vertically connected to both ends of the regulating plate portion 72a and extend upward.
72b and the mounting plate portions 72b and 72b are overlapped and abutted on the inner surfaces of the side support portions 54a and 54a of the frame body 54 to form a pair of bolts. 73, 73 by the side support portions 54a, 54a
Is combined with Thus, the mounting plate portion 72b is provided with four insertion holes 74 ... Corresponding to each vertex angle position of the right-angled quadrangle, and two insertion holes 74 ... At the diagonal positions of the right-angled quadrangle. The mounting plate portion 7 is fixed by the bolts 73, 73 that are inserted into the
2b is coupled to the side support portions 54a, and by doing so, the stopper 72 is attached to the side support portions 54a, 54a without selecting the left and right of the two mounting plate portions 72b, 72b.

The stopper 72 has a function of restricting the upper limit position of the cutter housing 25 by bringing the upper surface of the cutter housing 25 into contact with the restriction plate portion 72a.
7 and the function of covering the connecting portion of the pitman arm 48 from below.

On both sides of the frame body 54 on the rear side of the stopper 72, both ends of the both side support portions 54a, 54a are supported.
Pedal shaft 75 projecting outward from 4a and 54a
The lower end of a brake lever 76 arranged on the platform 16b integrally provided on the cover 16 on the right side of the column portion 16a is rotatably supported at one end of the pedal shaft 75. A brake pedal 77 is attached to the upper end of the brake lever 76.
Further, the column portion 16a is provided at the other end of the pedal shaft 75.
A lower end of a clutch lever 78 disposed on the platform 16c integrally provided on the cover 16 on the left side of the is pivotally supported, and a clutch pedal 79 is attached to the upper end of the clutch lever 78. Moreover, an interlocking link mechanism 80 arranged in the support frame 15 is provided between the brake lever 76 and the clutch lever 78, and the interlocking link mechanism 80 is provided for the brake lever 76 in response to the depression operation of the brake pedal 77. The rotation causes the clutch lever 78 to interlock and rotate, but the clutch pedal 79
The brake lever 78 is not interlocked with the rotation of the clutch lever 78 in response to the depression operation. Further, return springs 81, 8 are provided between the brake lever 76 and the clever lever 78 and the vehicle body frame 11.
2 are reduced respectively.

By the way, the side support portions 54a, 54a of the frame body 54 of the support frame 15 are provided with support flange portions 83, 83 which are folded back outward, and the support flange portions 8 thereof are provided.
The platform 16 of the cover 16 is provided on 3,83.
floor mount pipes 84, 84 supporting b, 16c
Is concluded. Both floor mount pipes 84, 84
Is fastened to the vehicle body frame 11 together with the second bracket 65, and the number of parts is reduced by sharing the fastening parts of the second bracket 65 and both floor mount pipes 84, 84 to the vehicle body frame 11. Further, in the side support portions 54a, 54a of the frame body 54, the support collar portions 85, 85 folded back outward are provided at positions above the support collar portions 83, 83, and these support collar portions 85 are provided. The cover 16 is directly fastened to the upper part of the cover 85.

To explain the operation of this embodiment, the steering shaft 50, to which the steering handle 49 is attached at the upper end, engages from below with the first bracket 56 detachably attached to the upper surface of the upper support portion 54b. The steering shaft 5 is inserted through the first bush 57 having the first collar portion 57a and the second bush 58 having the second collar portion 58a engaged with the upper surface of the lower support portion 55 from above.
0, the caulking protrusion 6 that engages with the lower surface of the first flange 57a.
0 ... are provided at a plurality of positions spaced in the circumferential direction, and the second
The drive gear 51, which is thrust-supported by the upper surface of the collar portion 58 a, is fixed to the steering shaft 50. Therefore, the upward movement of the steering shaft 50 is restricted by the caulking protrusions 60 ... Engaging with the first flange portion 57a from below, and the downward movement of the steering shaft 50 is caused by the second gear portion 58a. When the steering shaft 50 is regulated by abutting from above, the steering shaft 50 is rotatably supported by the first and second bushes 57 and 58 in a state where the vertical movement of the steering shaft 50 is regulated. Thus, the first bracket 56 is
The steering shaft 50 may be mounted on the support frame 15 from above and then mounted on the upper support portion 54b. Moreover, the rotation of the drive gear 51 relative to the steering shaft 50 is prevented and the shaft of the drive gear 51 is prevented by a very simple operation of fitting the pin 62 penetrating the steering shaft 50 into the fitting groove 61 of the drive gear 51. Second direction movement
The drive gear 51 is regulated by the bush 58 and the pin 62.
Can be substantially fixed to the steering shaft 50.

The rotating shaft 53 having the driven gear 52 fixed to the upper end is attached to the vehicle body frame 11 and the third bush 63 having the third flange portion 63a engaged with the upper surface of the lower support portion 55 from above. The driven gear 52 is thrust-supported on the upper surface of the third flange portion 63a by being inserted into the fourth bush 64 having the fourth flange portion 64a that is engaged with the second bracket 65 from below, and the fourth gear portion 64a A pitman arm shaft 66 is sandwiched between the lower surface and a support collar 70 that is fastened to the lower end of the rotary shaft 53 so that the pitman arm shaft 66 surrounds and rotates the rotary shaft 53 while being prevented from relative rotation. Therefore, the upward movement of the rotary shaft 53 is restricted by the upper end of the pitman arm shaft 66 coming into contact with the fourth flange 64a, and the downward movement of the rotary shaft 53 is caused by the driven gear 52 of the third flange 63a. The rotation shaft 53 is rotatably supported by the third and fourth bushes 63 and 64 in a state in which the vertical movement of the rotation shaft 53 is regulated.

The drive gear 51 and the driven gear 52 are meshed with each other above the lower support portion 55, and the upper support portion 54b, the lower support portion 55 and both side support portions 54a, 54a of the support frame 15 are Both gears 51, 5 are provided so as to protect the drive gear 51 and the driven gear 52 from the surroundings.
Since the gears 51 and 52 are arranged so as to surround the gears 2, it is possible to reliably prevent the gears 51 and 52, which are important parts, from falling down and protect the gears 51 and 52 with the support frame 15.
In addition, the steering shaft 50 to the pitman arm 48
Each component up to can be prepared as an assembly assembled to the support frame 15, and the assembly is assembled.
Assembling is easy because it can be attached to. Further, by disposing the second and third bushes 58, 63 on the lower support portion 55, it is possible to accurately determine the axial distance between the steering shaft 50 and the turning shaft 53.

A stopper 72 having a regulating plate portion 72a is fixed to the lower end of the support frame 15, and the upper limit position of the cutter housing 25 is regulated by the upper surface of the cutter housing 25 contacting the regulating plate portion 72a. To be done.
That is, when the riding lawn mower travels on the ground having steps or unevenness and the cutter housing 25 is pushed upward, the upper limit position is regulated by the regulation plate portion 72a. At that time, Since the regulation plate portion 72a extends horizontally substantially corresponding to the entire width of the vehicle body frame 11, even if the cutter housing 25 is tilted up to the left or right of the cutter housing 25, the regulation plate portion 72a is entirely contacted with the regulation plate portion 72a. The posture of the cutter housing 25 is corrected so that the cutter housing 25 is in contact with the cutter housing 25, and the thrust force is received by the entire surface of the regulation plate portion 72a, so that a large impact force is locally prevented from acting on the cutter housing 25.

Moreover, the stopper 72 is provided so as to connect the lower end portions of the side support portions 54a, 54a in the support frame 15, and can also perform the reinforcing function of the support frame 15, and further the support frame. It is also possible to cover the tie rods 47, 47 and the pitman arm 48 arranged in 15 from below to perform a protective function.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various design changes can be made without departing from the present invention described in the appended claims. It is possible.

[0042]

As described above, according to the first aspect of the invention, the support frame having the support portion is fixed to the vehicle body frame,
The steering shaft is inserted into and supported by the support portion, and the drive gear thrust-supported on the upper surface of the support portion is attached to the steering shaft, and the driven gear thrust-supported on the upper surface of the support portion and meshed with the drive gear is fixed to the upper end. The rotation axis is
A pitman arm is fixedly mounted on a cylindrical pitman arm shaft that is rotatably supported by a support portion and a bracket attached to a vehicle body frame, and is inserted into the rotary shaft below the bracket so that relative rotation is impossible. Since the arm shaft is sandwiched between the bracket and the support brim that is fastened to the lower end of the rotating shaft, it is possible to reliably regulate at least the downward movement of the steering shaft and the vertical movement of the rotating shaft. At the same time, both shafts can be rotatably supported with a simple structure that can be easily assembled and disassembled to improve maintenance workability, and that the number of parts is minimized, and the drive gear and driven gear can be supported. By engaging the gears above each other, it is possible to prevent both gears from falling off, and it is possible to accurately set the axial distance between the steering shaft and the turning shaft. It can be protected I can be the assembly work easier as possible to assemble in a temporarily assembled state the parts from the steering shaft until the pitman arm to the support frame.

According to a second aspect of the present invention, in addition to the configuration of the first aspect of the invention, the support frame has upper and lower support portions which are vertically spaced above the vehicle body frame. And a first bush attached to the first bracket having a first flange portion that engages from below with a first bracket detachably attached to the upper support portion, and an upper portion above the upper surface of the lower support portion. The steering shaft is rotatably supported by a second bush mounted on the lower support part and having a second flange part that engages with the drive gear and thrust-supports the drive gear. A plurality of caulking projections that engage with the lower surface of the section are provided at intervals in the circumferential direction,
A third bush that has a third flange portion that engages from above with the upper surface of the lower support portion and that is attached to the lower support portion; and a fourth bush that engages with the second bracket attached to the vehicle body frame from below.
Since the rotation shaft is rotatably supported by the fourth bush having the flange portion and attached to the second bracket, and the driven gear is thrust supported by the upper surface of the third flange portion, the first to fourth The steering shaft and the rotating shaft can be rotatably supported while restricting their axial movements with a simple and easily assembled structure using a bush.

According to the third aspect of the invention, in addition to the structure of the first or second aspect of the invention, the support frame includes a pair of side portion support portions fixed to both side portions of the vehicle body frame, respectively. A frame body having a substantially U shape having an upper support portion connecting upper ends of the side support portions, and a lower support provided between the vehicle body frame and the upper support portion and between both side support portions. Since the lower end of the steering shaft and the upper end of the rotating shaft are rotatably supported by the lower support, the upper support, the lower support, and both side supports support the drive gear and the driven gear. Can be enclosed to protect it from the environment.

Furthermore, according to the invention of claim 4, in addition to the structure of the invention of claim 1, 2 or 3, the upper surface of the drive gear extends in the radial direction of the steering shaft and has both ends. A closed fitting groove is provided, and a pin penetrating the steering shaft along its radial direction is fitted into the fitting groove, so that the pin inserted into the steering shaft is fitted into the fitting groove. The drive gear can be substantially fixed to the steering shaft.

[Brief description of drawings]

FIG. 1 is a side view of a riding lawn mower.

FIG. 2 is a plan view of a riding lawn mower.

FIG. 3 is an enlarged sectional view taken along line 3-3 of FIG. 1;

FIG. 4 is an enlarged sectional view taken along line 4-4 of FIG. 3;

FIG. 5 is a sectional view taken along line 5-5 in FIG. 4;

6 is a view taken along line 6-6 of FIG.

7 is a sectional view taken along line 7-7 of FIG.

8 is a sectional view taken along line 8-8 of FIG.

9 is an enlarged sectional view taken along line 9-9 of FIG.

[Explanation of symbols]

 11 ... Body frame 15 ... Support frame 48 ... Pitman arm 49 ... Steering handle 50 ... Steering shaft 51 ... Drive gear 52 ... Driven gear 53 ... Rotating shaft 54 ... Frame 54a ... Side support 54b ... Upper support 55 ... Lower support 56 ... First bracket 57 ... First bush 57a ... First flange 58・ ・ ・ Second bush 58a ・ ・ ・ Second flange 60 ・ ・ ・ Caulking protrusion 61 ・ ・ ・ Mating groove 62 ・ ・ ・ Pin 63 ・ ・ ・ Third bush 63a ・ ・ ・ Third flange 64 ・..Fourth bush 64a ... Fourth collar portion 65 ... Second bracket 66 ... Pitman arm shaft 70 ... Support collar

Claims (4)

[Claims] 1. A steering shaft (50) having a steering handle (49) attached to an upper end thereof, and a drive gear (5) movably attached to the steering shaft (50).
1), a rotary shaft (53) having an axis line substantially parallel to the steering shaft (50) and having a pitman arm (48) connected thereto, and a rotary shaft (5) meshing with the drive gear (51). In a steering device for a work vehicle, comprising: a driven gear (52) fixed to a support portion (5).
A support frame (15) having a steering shaft (50) is fixed to the vehicle body frame (11), and
The drive gear (51) which is inserted into and supported by the steering shaft (5) and is thrust-supported by the upper surface of the support portion (55).
Driven gear (52) that is attached to the drive gear (51) and is thrust supported on the upper surface of the support portion (55).
The rotating shaft (53) fixed to the upper end of the
And a bracket (6 attached to the body frame (11)
5) is rotatably supported by the pitman arm (48) on a cylindrical pitman arm shaft (66) which is fitted to the rotary shaft (53) below the bracket (65) so that relative rotation is impossible. Fixed and Pitman Arm Axis (66)
Is sandwiched between a bracket (65) and a support collar (70) that is fastened to the lower end of the rotating shaft (53). 2. The body frame (1) is attached to the support frame (15).
1) upper and lower support portions (54b, 55) arranged at intervals above and below the upper support portion (1b) are provided, and a first bracket (56) detachably attached to the upper support portion (54b) engages from below. The first bush (57), which has a matching first flange portion (57a) and is attached to the first bracket (56), is engaged with the upper surface of the lower support portion (55) from above and the drive gear (51). ) Thrust support second
A steering shaft (50) is rotatably supported by a second bush (58) which has a collar portion (58a) and is attached to a lower support portion (55), and the steering shaft (50) includes:
The caulking protrusion (6) that engages with the lower surface of the first collar (57a)
0) are provided at intervals in the circumferential direction and are engaged with the upper surface of the lower support portion (55) from above by the third flange portion (63).
The third bush (63) having a) and attached to the lower support part (55), and the fourth collar part (64a) engaged with the second bracket (65) attached to the vehicle body frame (11) from below. ), The rotation shaft (53) is rotatably supported by the fourth bush (64) attached to the second bracket (65), and the driven gear (52) includes the third flange portion (63a). The steering apparatus for a work vehicle according to claim 1, wherein the steering apparatus is thrust-supported by the upper surface of the steering wheel. 3. The support frame (15) is a body frame (1).
1) having a pair of side support parts (54a) fixed to both side parts and an upper support part (54b) connecting the upper ends of the side support parts (54a) to each other and having a substantially U shape. The steering shaft (54) and the lower support portion (55) provided between the vehicle body frame (11) and the upper support portion (54b) between both side support portions (54a). The steering device for a work vehicle according to claim 1 or 2, wherein a lower end portion (50) and an upper end portion of the rotating shaft (53) are rotatably supported by a lower support portion (54b). 4. A fitting groove (61) extending along the radial direction of the steering shaft (50) and having both ends closed is provided on the upper surface of the drive gear (51), and the steering shaft (50) has a radius equal to that of the fitting groove (61). Pins piercing along the direction (62)
The steering device for a work vehicle according to claim 1, 2 or 3, characterized in that: is fitted in the fitting groove (61).