JP4219261B2 - Steering structure of passenger rice transplanter - Google Patents

Description

  The present invention relates to a steering structure for a riding rice transplanter in which a seedling planting device is connected to a rear portion of a four-wheel drive type traveling machine body having left and right front wheels that can be steered and rear wheels that cannot be steered.

As the steering structure of the above-mentioned passenger rice transplanter, a structure in which the left and right front wheels are steered by a rack and pinion type steering mechanism in which the rack cage moves linearly by occlusion with a pinion gear interlocked with the steering handle is proposed. (For example, refer to Patent Document 1).
Japanese Patent Laid-Open No. 2003-16 (FIG. 4)

  In the steering structure described above, a known Ackermann type steak rink is constructed in which knuckle arms provided on the left and right front wheels are connected by tie rods, and the steer rink is operated to be displaced by a rack rod of a rack and pinion type steering mechanism. Therefore, since the rack and pinion type steering mechanism needs to be arranged so as not to interfere with the steer link, the steering mechanism is disposed in an oblique posture, and the steering handle and the steering mechanism disposed above the engine are arranged. Due to the relationship of interlocking connection with the pinion operating shaft by the steering operating shaft that bypasses the side of the engine, the steering mechanism has been deployed in a state deviated laterally where the steering operating shaft is deployed. For this reason, the space occupied by the entire front wheel steering structure is large in the front-rear direction.

  By the way, when the planting run of one stroke is finished and the aircraft is turned around by U-turn at the heel and the direction is reversed, the space for changing the direction of the aircraft left along the ridge, so-called headland, It is desirable to form a width with no excess or deficiency for one round planting performed later. For example, in a small rice transplanter with a 4-row planting specification, it is necessary to form a headland with a 4-row planting width. Thus, in order to change the direction of the aircraft while leaving a small headland, the U-turn will be performed with the aircraft sufficiently close to the heel, and the structure of the front of the aircraft to make the aircraft sufficiently close to the heel It is particularly desired to reduce the size of the steering wheel, and it is not preferable to increase the size of the entire steering structure as described above.

  The present invention has been made paying attention to such points, and has as its main object to provide a steering structure that can be effectively used in a riding rice transplanter.

A first invention is a steering structure of a riding rice transplanter in which a seedling planting device is connected to a rear portion of a four-wheel drive type traveling machine body having left and right front wheels that can be steered and rear wheels that cannot be steered. Rotating cases that pivotally support the front wheels are supported on the left and right sides of the transmission case provided at the front of the machine body and equipped with a traveling transmission gearbox, and left and right at the lower front end of the transmission case. In addition, a boss is provided integrally with the transmission case, and through a rack bush of a rack and pinion type steering mechanism through the left and right bosses, via bearing bushes fitted to the outer end portions of the bosses. It said rack rod is supported so as to be horizontally slide, to interior supports the pinion operating shaft having the lower the lap rod meshing with the pinion gear between the left and right boss while standing on the transmission case, before Characterized in that the left and right ends of the rack rod and the left and right of the rotary case are interlockingly connected with linkage rod.

  According to the above configuration, the steering structure of the front wheel can be configured by interlockingly connecting the left and right ends of the rack rod and the knuckle arms extending from the left and right rotating cases with the linkage rod. And the front wheel axle which assembled | attached the rotation case of the front wheel and the whole steering structure to the transmission case can be comprised previously.

  Therefore, according to the first invention, the steering structure having the rack and pinion type steering mechanism can be disposed in the front-rear direction below the front of the fuselage in a compact manner, and the front-rear direction can be reduced in the front-rear direction. As a result, it is possible to turn the U-turn at the heel with the aircraft sufficiently close to the heel, and a headland with a desired width can be easily formed.

  Also, since the front wheel axle can be assembled in advance, compared to the case where a separately mounted rack and pinion type steering mechanism is separately attached to the fuselage and the rack cage and the left and right rotating cases are linked together The assembly workability is excellent.

  In the steering structure of the riding rice transplanter according to the second invention, in the first invention, a large-diameter portion that avoids a tooth portion of the rack rod is formed in a part of the bearing bush in the circumferential direction of the bearing bush. It is characterized by that.

  According to the above configuration, even if the rack rod slides by steering operation, the inner periphery of the bearing bush is not scraped by the tooth portion of the rack rod, and the bearing bush can be used with high durability.

  The steering structure of the riding rice transplanter according to a third aspect of the present invention is the positioning structure for holding the bearing bush in a constant circumferential direction between the inner periphery of the boss and the outer periphery of the bearing bush. An engaging portion is provided.

  According to the above configuration, the bearing bush can be assembled to the boss only in a posture in which the large diameter portion of the inner periphery of the bearing bush faces the tooth portion of the rack rod, and assembly without phase error is possible. The actions and effects of the invention can be exhibited accurately.

A steering structure of a riding rice transplanter according to a fourth aspect of the present invention is the steering structure according to any one of the first to third aspects, wherein the transmission case is configured in a left-right split structure, and the pinion operating shaft is formed on a split surface of the transmission case. It is located and supported by the transmission case.

  According to the above configuration, the pinion operating shaft is supported by sandwiching the pinion operating shaft between the split surfaces of the transmission case and joining the transmission case with the pinion gear meshed with the rack cage inserted through the left and right bosses. As a result, the rack and pinion type steering mechanism can be easily assembled as compared with a structure in which a pinion operating shaft is inserted into a mounting hole formed in the transmission case.

  A steering structure of a riding rice transplanter according to a fifth aspect of the present invention is the steering structure according to any one of the first to fourth aspects, further comprising a pair of side clutches for intermittently transmitting and receiving power to the left and right rear wheels. It has an automatic steering mechanism that automatically disengages the side clutch for the rear wheel on the inside of the turn in conjunction with the steering operation of the wheel to the left or right beyond the set angle from the straight position. It is characterized by.

  According to the above configuration, when the front wheel is steered greatly in the direction change of the body at the shore, the side clutch of the rear wheel which automatically turns inside is disengaged, and the left and right front wheels and the rear wheel outside the turning 3 Make a small turn in wheel drive. In this case, the rear wheel on the inside of the turn with the side clutch disengaged is in an idle state, and is not fixed while being stuck in the field, and rotates without difficulty for dragging accompanying the turning of the body.

  Therefore, according to the fifth aspect of the invention, it is possible to easily and lightly change the direction at the heel, bring about the effects of any one of the first to fourth aspects of the invention, and have excellent maneuverability. Become.

  The whole side surface of the rice transplanter concerning this invention is shown by FIG. 1, and the whole plane is shown by FIG. 2, respectively. This rice transplanter has a parallel quadruple link structure that is driven by a hydraulic cylinder 4 at the rear of a four-wheel drive type traveling machine body 3 having a front wheel 1 that can be steered and a rear wheel 2 that cannot be steered. A seedling planting device 6 is connected via a mechanism 5, and a fertilizer device 8 is provided at a rear portion of a driver seat 7 provided at a rear portion of the traveling machine body 3, and an engine bonnet 9 is disposed at a front portion of the traveling machine body 3. A front panel 10, a steering handle 11, and the like are provided. Further, a reserve seedling base 12 is vertically installed on the left and right sides of the engine bonnet 9.

  The seedling planting device 6 is configured in a four-row planting specification, and seedlings are placed on the seedling stage 15 on which the seedlings are placed and reciprocated horizontally by a fixed stroke. It comprises four sets of rotary planting mechanisms 16 planted on the surface, three leveling floats 17 for leveling the planting location on the surface, and the like.

  The fertilizer applicator 8 feeds the powdered fertilizer stored in the fertilizer hopper 18 by a set amount by a feeding mechanism 19 provided at the lower end portion of the hopper, and supplies the fed fertilizer by four conveying air from the electric blower 20. It is sent out to the hose 21, transported by wind to the four groovers 22 attached to the leveling float 17, and fertilizer is fed into the fertilizer grooves formed on the surface near the side of the planted seedling by the groovers 22. It is configured to be buried.

  A transmission case 25 that supports the front wheel 1 and the rear wheel 2 is disposed at the front of the traveling body 3. The transmission case 25 is configured by joining and connecting left and right divided case portions 25L and 25R. The front wheel 1 is attached to an end portion of a front axle case portion 25a projecting laterally from the front left and right of the transmission case 25. A rotating case 26 that is pivotally supported is provided so as to be steerable around the longitudinal center P. In addition, a pair of left and right swing cases 28 elastically supported by a suspension mechanism 27 are mounted on the rear portion of the transmission case 21 so as to be able to swing independently up and down around a fulcrum a. Each of the wheels 2 is pivotally supported, and an engine 29 accommodated in the engine bonnet 9 is mounted on a front frame 30 protruding forward from the transmission case 25.

  As shown in FIG. 3, the engine 29 is a horizontal shaft type air-cooled gasoline engine with an output shaft 31 protruding leftward, and a cylinder portion 29b connected to the upper portion of the crankcase 29a is rearward. It is configured to be inclined and low in volume, and the front end lower portion of the crankcase 29a and the cylinder portion 29b are mounted on the front frame 30 in a vibration-proof state via a vibration-proof rubber 32.

  In addition, a fuel tank 32 is provided in the upper part of the engine bonnet 9, and an auxiliary lever 33 is used at the front end of the front frame 30 that is used when the driver moves on a slope where the driver descends to the ground and steers. In this way, it is mounted so as to be able to swing back and forth around the lower fulcrum b within a certain range extending from the stowed upright posture and the acting posture swinging forward and swinging over the bag, to the platform of the transport vehicle When the self-propelled vehicle is tilted back and forth as in the case of the unloading, the front lever of the fuselage is prevented from being lifted by the driver who descends to the ground pushing the auxiliary lever 33 swinging out to the action posture.

  FIG. 6 shows an outline of the transmission structure in this rice transplanter.

  A hydraulic continuously variable transmission (HST) 35 is connected to the left side surface of the transmission case 25 as a main transmission, and an output shaft 31 of the engine 29 and an input shaft (pump shaft) of the continuously variable transmission 35. 36 is wound and interlocked via a belt 37, and the shift output taken out from the output shaft (motor shaft) 38 of the continuously variable transmission 27 is transmitted to the input shaft 39 of the transmission case 25. After being transmitted to the two shafts 40, it is branched into a traveling system and a planting system and transmitted as follows.

  [Running transmission system]

  The transmission case 25 is equipped with a differential device 41 for the front wheel 1, and a wheel drive transmission shaft 42 extending from the differential device 41 to the left and right so as to be differentially driven is a front axle case of the transmission case 25. An insertion support is provided at 25a. The input cylinder shaft 43 of the differential device 41 is loosely fitted to one (right side in this example) of the transmission shaft 42, and the input cylinder shaft 43 and the second shaft 40 serve as the auxiliary gear transmission 44 for traveling. By shifting the shift gear 45, which is interlocked and connected to the input cylinder shaft 43, to the left and right, and selectively engaging the large and small gears 45a and 45b with the gears 46a and 46b provided on the second shaft 40, The traveling system power shifted in two stages is transmitted to the input cylinder shaft 43.

  As shown in FIG. 5, a longitudinal transmission shaft 47 is inserted along the longitudinal axis P in the rotation case 26 that is rotatably mounted around the longitudinal axis P at the outer end of the front axle case 25 a. The upper end of the vertical transmission shaft 47 and the transmission shaft 42 are connected to each other via a bevel gear transmission mechanism 48, and the front axle 49 and the vertical transmission shaft 47 supported on the lower portion of the rotating case 26 are supported. The lower end is linked and connected through a bevel gear reduction transmission mechanism 50.

  As shown in FIG. 8, a rear axle case 25b is integrally projected on the left and right of the rear end portion of the transmission case 25, and a pair of left and right wheels disposed concentrically with the fulcrum a of the swing case 28 is provided on the rear axle case 25b. The lateral transmission shaft 51 is inserted and supported in a butted state, the output sprocket 52 fixed to the input cylinder shaft 43 of the differential device 41, and the input sprocket 53 loosely fitted to the butted end portions of the both lateral transmission shafts 51. The chain 54 is wound around the input sprocket 53, and the left and right lateral transmission shafts 51 are linked to each other via the side clutch 55.

  The swing case 28 is loosely fitted in a rear-side cantilever manner so as to be pivotable up and down at the outer end portion of the rear axle case 25b, and the front end portion of the front-rear transmission shaft 56 inserted through the swing case 28 and the lateral transmission shaft 51, Are coupled to each other via a bevel gear transmission mechanism 57, and the rear axle 58 provided at the rear end of the swing case 28 and the rear end of the front-rear transmission shaft 56 are coupled to each other via a bevel gear reduction transmission mechanism 59. Thus, the left and right rear wheels 2 are driven in synchronism with the front wheels 1 and can be moved up and down independently.

  As shown in FIG. 8, the side clutch 55 is configured as a multi-plate friction clutch, and a clutch drum 61 on the drive side is fixed to the left and right side surfaces of the input sprocket 53 and driven by the lateral transmission shaft 51. The clutch boss 62 on the side is splined, and a plurality of friction plates 63 engaged and supported by the clutch drum 61 and a plurality of friction plates 64 engaged and supported by the clutch boss 62 are alternately superposed and arranged. By urging and shifting laterally outwardly by a spring 65 having an internal structure 62, the friction plates 63 and 64 are pressed against each other, thereby bringing about a “clutch engaged” state in which power is transmitted from the clutch drum 61 to the clutch boss 62. Further, the clutch boss 62 is moved backward against the spring 65 to release the pressure contact between the friction plates 63 and 64, whereby the clutch drum 61 Cut off the power transmission "clutch disengaging" state is adapted to be brought to the Luo clutch boss 62.

  The rear axle case 25b is fitted with a clutch operating shaft 66, and the clutch operating shaft 66 is rotated to displace an eccentric pin 66a formed on the inner end thereof in the left-right direction. It is designed to operate.

  A brake 68 acting on the clutch drum 61 in one (left side in this example) side clutch 55 is provided. The brake 68 includes a ring-shaped friction plate 69 that is externally fitted to the clutch drum 61 and engaged with the engagement groove of the side clutch friction plate 63, and a ring that is non-rotatably engaged with the inner surface of the transmission case 25. And an operating arm 71a connected to the brake operating shaft 71 by rotating a brake operating shaft 71 penetratingly attached to the transmission case 25. Thus, the clutch drum 61 and the input sprocket 53 integrated with the clutch drum 61 are braked by pressing the friction plates 69 and 70 together.

  The brake operation shaft 71 is linked to a brake pedal 72 arranged on the right front side of the driving step 13, and the input sprocket 53 is braked by depressing the brake pedal 72. The rear wheel 2 and the left and right front wheels 1 can be braked simultaneously. Although a detailed structure is not shown, a tension type main clutch 73 and a brake pedal 72 acting on a belt 37 that interlocks and connects the engine 29 and the continuously variable transmission 35 are linked to each other, and the brake pedal 72 is depressed. As a result, the airframe stops and the main clutch 73 is disengaged, and the transmission of engine power to the continuously variable transmission 35 is cut off.

  Further, a brake operation lever 74 is integrally fixed to the brake pedal 72 and extends toward the front of the aircraft. When the driver descends to the ground and steers, the brake operation lever 74 is pushed down to depress the brake operation lever 74 from the ground. A stop operation can be performed.

  [Planting transmission system]

  As shown in FIG. 7, a third shaft 81 is loosely fitted concentrically on the input shaft 39 of the transmission case 25, and the third shaft 81 and the second shaft 40 perform a three-stage speed change. The gears 82 are linked together. Then, after the power extracted from the third shaft 81 is converted into power in the front-rear direction via the gear pairs 83 and 84 outside the case and the bevel gear transmission mechanism 85, the PTO shaft is transmitted via the torque limiter 86 and the planting clutch 87. 88 to be transmitted. The PTO shaft 88 is provided so as to protrude rearward from the upper portion of the transmission case 25, and the power of the planting system taken out from the PTO shaft 88 moves up and down via a shaft transmission mechanism 89 that can be expanded and contracted. Is transmitted to the seedling planting device 6.

  In addition, it is possible to change the stocks that can be selected in three stages as a whole by exchanging or exchanging the gear pairs 83 and 84 arranged outside the case.

  Further, as shown in FIG. 8, an intermediate PTO shaft 91 is horizontally supported near the rear portion of the transmission case 25, and a sprocket 92 loosely fitted to the intermediate PTO shaft 91 is provided in the transmission system to the rear wheel 2. It is engaged with an intermediate portion of the chain 54. Further, a clutch boss 93 that can be engaged and disengaged from the side is splined to the intermediate PTO shaft 91 so as to be shiftable. The intermediate PTO shaft 91 is engaged with the sprocket 92 by shifting the clutch boss 93 by a spring 94. The power synchronized with the traveling speed can be taken out from the shaft 91, and the clutch boss 93 can be reversely shifted against the spring 94 and detached from the sprocket 92 so that the power can be taken out. It has become. The case outer end of the intermediate PTO shaft 91 and the feeding mechanism 19 in the fertilizer application 8 are interlocked and connected by a crank type transmission mechanism 95. In this way, by driving the feeding mechanism 19 at a predetermined ratio with respect to the traveling speed, the fertilizer feeding amount per unit traveling distance (unit area) is always set to the set value (the feeding mechanism 19) even if the strain is changed by inter-shaft shifting. Can be maintained). In addition, in the model of the specification which does not have the fertilizer application device 8, it is not necessary to take out power from the intermediate PTO shaft 91.

  Next, a steering structure for steering the front wheel 1 will be described.

  As shown in FIG. 4, a knuckle arm 101 is attached to the left and right rotating cases 26 that pivotally support the front wheel 1, and the left and right knuckle arms 101 are interlocked and connected to a rack and pinion type steering mechanism 102. A front wheel axle is constructed. As shown in FIGS. 5, 9, and 10, the steering mechanism 102 is disposed in a corner portion of the lower front end of the transmission case 25 in parallel with the transmission shaft 42 for driving the front wheels. The rack 杆 103 is pierced and supported so as to be slidable from side to side over the protruding boss 25 c, and the pinion gear 104 is engaged with a tooth portion 103 a formed on the rear surface of the rack 杆 103. Then, both end portions of the rack cage 103 projecting left and right from the transmission case 25 and the left and right knuckle arms 101 are interlocked and connected by a spherical joint 105 and a linkage rod 106.

  The pinion gear 104 is fixed to a lower portion of a pinion operation shaft 108 that is inserted and arranged in a vertical position at the front portion of the transmission case 25, and the upper end of the pinion operation shaft 108 is a hydraulic pressure attached to the upper end of the transmission case 25. The operation shaft 109a connected to the output shaft 109b of the power steering unit 109 and the steering handle 11 provided on the upper surface of the power steering unit 109 are interlocked and connected via the upper and lower universal joints 110 and the steering operation shaft 111. Yes. Therefore, by rotating the steering handle 11, the pinion operating shaft 108 is powerfully rotated via the power steering unit 109, and the rack 103? The rotating case 26 and the front wheel 1 pivotally supported by the rotating case 26 are steered in the steering wheel rotating direction.

  The pinion operating shaft 108 is vertically positioned between the internal transmission mechanism incorporated in the transmission case 25 and the front wall of the case so as to be positioned on the dividing line in the transmission case 25 having a left-right split structure and to be positioned at the center in the left-right direction of the airframe. The lower end protrudes downward from the pinion gear 104 and the protruding shaft portion is supported by the transmission case 25 via a bearing 112 such as a ball bearing. Further, the power steering unit 109 arranged concentrically with the pinion operating shaft 108 is also located on the dividing line in the transmission case 25 of the left and right divided structure, but is bolted and connected only to the upper surface of the right divided case portion 25R, Even if the power steering unit 109 is not removed, only the left divided case portion 25L can be separated for maintenance inside the case.

  Bearing bushes 115 made of an oil-impregnated sintered metal are fitted into the ends of the left and right bosses 25c that pass through and support the rack cage 103, and are prevented from coming off by retaining rings 116. The rack cage 103 is supported across these bearing bushes 115 with a large span. Here, as shown in FIGS. 11 and 12, a large-diameter portion 117a that avoids the teeth 103a of the rack cage 103 is formed in a part of the bearing bush 115 in the circumferential direction of the bearing hole 117, and the inner periphery of the boss 25c. By engaging the positioning engaging portion 118 formed in the recessed portion with the positioning engaging portion 119 protruding from the outer periphery of the bearing bush 115, the bearing bush 115 is assembled and held in a constant circumferential posture. Thus, the inner periphery of the bearing bush 115 is prevented from being scraped by the tooth portion 103a even if the rack cage 103 slides left and right.

  A bellows-like stretchable boot 107 made of a rubber material is mounted across the boss 25c of the transmission case 25 and the end of the linkage rod 106, and the rack cage 103 and the joint 105 are protected from muddy water. At both ends of the stretchable boot 107, cylindrical portions 107a and 107b are formed which are closely fitted in close contact with the boss 25c and the connecting rod 106 in the axial direction, and are formed on the inner circumferences of the cylindrical portions 107a and 107b. An annular protrusion 121 is fitted into annular grooves 122 and 123 formed on the outer periphery of the boss 25c and the connecting rod 106, and a band 124 is wound around the outer periphery of each of the cylindrical portions 107a and 107b. Cylindrical portions 107a and 107b at both ends of the 107 are connected to the boss 25c and the connecting rod 106 in an airtight manner so that they cannot be pulled out in the axial direction.

  Thick flange portions 107c and 107d are connected to the outer end portion of the cylinder portion 107a that is externally fitted to the boss 25c and the inner end portion of the cylinder portion 107b that is externally attached to the linkage rod 106. In addition, the thick and rigid flange portions 107c and 107d make it easy to handle when removing the flexible elastic boot 107.

  The joint 105 includes a receiving portion 125 connected to the end portion of the rack cage 103, a spherical end portion 106a provided at the distal end portion of the linkage rod 106, and a receiving portion that can turn the spherical end portion 106a in a three-dimensional direction. The cap 126 is screwed onto the receiving portion 125 so as to be held against the tip of the 125, and a constricted portion e is formed at the base of the spherical end portion 106a of the linkage rod 106, whereby the joint 105 is bent. A large angle is secured.

  As shown in FIGS. 5 and 11, a sheet metal protective cover 127 that covers the steering mechanism 102 configured as described above from the front is attached to the lower portion of the front end of the transmission case 25. The steering mechanism 102 is prevented from directly colliding with the heel during the conversion. The protective cover 127 has a width that covers the steering mechanism 102 over substantially the entire length when traveling straight, and its upper part is bolted to the transmission case 25 at two left and right sides, and its lower end is transmitted. The case 25 is abutted and supported at the lower end of the case 25. And in order to ensure the intensity | strength with respect to a collision with a ridge etc., the folding rib 127a is formed along the upper end side of a cover, and the several ejection rib 127b which bulges forward in the up-and-down intermediate part is formed. .

  Further, the steering structure and the left and right side clutch 55 for the rear rear wheel 2 are linked to each other, and the automatic steering for automatically disengaging the side clutch 55 of the rear wheel 2 on the inside of the turn in conjunction with the aircraft steering operation. Mechanism A is provided.

  As shown in FIGS. 4 and 13, the automatic steering mechanism A is configured such that the left and right knuckle arms 101 and the operation lever 66 a of the left and right clutch operation shafts 66 are crossed by a linkage rod 113 having a long hole interchange c. As shown in FIG. 13 (a), when the front wheel 1 is in the straight running position, both the left and right side clutches 55 are in the “clutched” state, and straight running with four-wheel drive is possible. Done. When the front wheel 1 is steered less than the set angle (several tens of degrees) from this straight traveling state, the rotational displacement of the knuckle arm 101 is absorbed by the long hole interchange c, and the linkage lock 113 is operated. The left and right side clutches 55 are both maintained in the “clutch engaged” state. In other words, the automatic steering mechanism does not work for the steering that slightly changes the direction of the aircraft. Then, when the front wheel 1 is steered largely, for example, to the left by a set angle (several tens of degrees) or more from a straight traveling state for a U-turn turning at the shore, as shown in FIG. Further, the right knuckle arm 101 is pivotally displaced larger than the long hole interchange c, and only one linkage rod 113 linked to the left clutch operating shaft 66 is pulled forward and displaced, and only the left clutch operating shaft 66 is displaced. Is operated forward. Accordingly, in this case, the side clutch 55 of the left rear wheel 2 on the inner side of the turn automatically enters the “clutch disengaged” state, and the rear wheel 2 on the inner side of the turn enters the idle state, and the left and right wheels steered to the left largely The vehicle turns to the left with a small turning radius by three-wheel drive by the front wheel 1 and the right rear wheel 2 on the outside of the turn.

  The hydraulic power source of the power steering unit 109 and the hydraulic cylinder 4 for raising and lowering the seedling planting device and the hydraulic pump 114 serving as the charge hydraulic power source of the continuously variable transmission 35 are extended from the input shaft 36 of the continuously variable transmission 35. It is driven by the power extracted from the end. The hydraulic pump 114 uses the lubricating oil stored in the transmission case 25 as hydraulic oil, and the oil extracted from the lower front portion of the transmission case 25 passes through the cartridge type filter 120 as shown in FIGS. The filter 120 is sucked by the hydraulic pump 114, and the filter 120 and the hydraulic pump 114 are connected to each other via an in-wall oil passage d formed on a split surface in the transmission case 25.

  [Other Examples]

  (1) The steering structure of the present invention can also be applied to a front wheel axle of a rice transplanter having a specification in which an engine is mounted on the rear part of a traveling machine body.

  (2) The steering structure of the present invention can also be applied to a rice transplanter having a specification in which the front wheel axle is supported so as to be able to roll freely.

Whole side view of rice transplanter Overall plan view of rice transplanter Side view of the front of the aircraft Partially cutaway plan view showing the aircraft's traveling system Front view showing front wheel axle Transmission system diagram A longitudinal rear view showing the internal structure of the transmission case Cross-sectional plan view showing the power branch to the rear wheels Longitudinal side view of the front of the transmission case Longitudinal front view showing part of the steering structure Longitudinal side view of steering structure An exploded perspective view showing a part of the steering structure Schematic plan view showing automatic steering operation

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Front wheel 2 Rear wheel 3 Traveling machine body 6 Seedling planting device 25 Transmission case 25a Boss 26 Rotating case 55 Side clutch 102 Steering mechanism 103 Rack hook 103a Tooth part 104 Pinion gear 105 Joint 106 Link rod 108 Pinion operation shaft 115 Bearing bush 117 Bearing Hole 117a Large diameter part A Automatic steering mechanism

Claims (5)

In the steering structure of a riding rice transplanter in which a seedling planting device is connected to a rear portion of a four-wheel drive type traveling machine body having left and right front wheels which can be steered and rear wheels which cannot be steered,
The rotary case that rotatably supports the front wheel, supported on the left and right of the transmission case you have interiors with a transmission of the deployed and traveling transmission system to the body front, left and right in front subordinate part of the transmission case The transmission case has a boss integrally therewith , and the rack and pinion type steering mechanism rack pierced through the left and right bosses, and through the bearing bushes fitted to the outer ends of the bosses. The rack cage is supported so as to be slidable left and right, and a pinion operating shaft having a pinion gear that engages with the lap cage between the left and right bosses is supported in an upright state in the transmission case, and left and right of the rack cage A steering structure for a riding rice transplanter, characterized in that both ends and the left and right rotating cases are interlocked and connected by a connecting rod.   The steering structure of a riding rice transplanter according to claim 1, wherein a large-diameter portion that avoids a tooth portion of the rack rod is formed in a part of a circumferential direction of the bearing hole in the bearing bush.   3. The riding rice transplanter according to claim 2, wherein a positioning engagement portion is provided between the inner periphery of the boss and the outer periphery of the bearing bush for holding the bearing bush in a constant circumferential posture. Steering structure. The said transmission case is comprised in the right-and-left division | segmentation structure, The said pinion operating shaft is located in the division | segmentation surface of the said transmission case, and is supported by the transmission case. Steering structure of a passenger rice transplanter.   A pair of side clutches for intermittently transmitting and receiving power to the left and right rear wheels are provided, and the inside of the turn is interlocked with the steering of the front wheels to the left or right beyond the set angle from the straight travel position. The steering structure of the riding rice transplanter according to any one of claims 1 to 4, further comprising an automatic steering mechanism that automatically disengages a side clutch for a rear wheel.

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