Embodiments according to the present invention will be described below in detail with reference to the drawings.
An agricultural tractor as a work vehicle performs work on a farm field or the like while self-propelled by power. The agricultural tractor includes front wheels 2L and 2R that can be driven and steered on the front side of the body 1, crawler travel devices 3L and 3R mounted on the rear side of the body 1, an engine 4 as a power source, and a transmission. An internal transmission case 5 is provided. In addition, as a traveling apparatus, it is set as the semi-crawler form by the front wheels 2 and 2 and the crawler traveling apparatuses 3L and 3R.
In addition, a connecting device 7 on which a work machine 6 such as a rotary can be mounted is disposed at the rear of the machine body 1. The connecting device 7 is a three-point link comprising a top link 7a at the center upper portion and lower left and right lower links 7b, 7b, and a lift arm (not shown) is hydraulically rotated to lower the lower link via a lift rod (not shown). It is the structure which rotates the link 7b and raises / lowers the working machine 6.
The tractor 1 is covered with a cabin 8 around the cockpit on the fuselage. Inside the cabin 9, a steering handle is erected from the dashboard in front of the cockpit, and various operation pedals such as a clutch pedal, a brake pedal, an accelerator pedal, a forward / reverse lever, a shift lever, etc. An operation lever is arranged.
The crawler travel devices 3L and 3R will be described. The crawler travel device has a pair of left and right configurations. In each of the reference numerals for explanation, L is used to indicate the left side, R is used to indicate the right side, and the left and right sides are described. , L or R may be used for description.
As shown in FIG. 1, the crawler travel devices 3L and 3R include drive sprockets 10L and 10R interlocked with the drive shafts 9L and 9R, front extension wheels 11L and 11R, rear extension wheels 12L and 12R, A plurality of idler wheels (three left and right in the illustrated example) 13L, 13R..., And these sprockets, front and rear stretched wheels, rubber crawlers 14L and 14R around which the idler wheels are wound, and the drive sprockets 10L and 10R The rubber crawlers 14 </ b> L and 14 </ b> R are moved in a wound state by rotation.
Rear axle cases 15L and 15R are provided extending from the rear portion of the transmission case 5 to the left and right, and final deceleration cases 16L and 16R are integrally formed at respective ends of the rear axle cases 15L and 15R. The drive sprockets 10L and 10R of the crawler travel devices 3L and 3R are mounted on the drive shafts 9L and 9R that are pivotally supported by the final deceleration cases 16L and 16R, respectively. The final reduction case 16 is internally provided with a reduction mechanism with a predetermined reduction ratio that is a combination of a pair of spur gears.
The front and rear tension wheels 11 and 12 and the idler wheel 13 are supported by a track frame 17. The track frame 17 has a swing boss portion 17b that forms a hole portion 17a for passing a swing shaft at the top, a front base 17f for mounting the front tensioning wheel 11, and a rear for mounting the rear tensioning wheel 12. The side pedestal 17r, the lower frame 17c for supporting the idle wheels 13, 13,..., And the upper frame portions 17d, 17e that can hold the swing boss portion 17b.
On the lower surface of the rear part of the transmission case 5, a support shaft frame 19 is provided to be fixed to the left and right. That is, the support frame 19 rigidifies the pair of front and rear plate members 19a and 19b that are long on the left and right sides, and the end plates 19c and 19c and the central plate 19e in a bridging manner with appropriate spacing by means such as welding. In addition, the supporting shaft holding metals 19f, 19f,... Are welded to the right and left end portions as appropriate. Accordingly, shaft support portions 20L and 20R are formed on the left and right portions of the support shaft frame.
Track frames 17L and 17R are pivotally connected to the shaft support portions 20L and 20R by swing shafts 21L and 21R, respectively. That is, the swing boss portion 17b of the track frame 17 can enter between the support shaft holding metals 19f and 19f from below, and the through holes of the support shaft holding metals 19f and 19f and the hole portion 17a of the swing boss portion 17b By making the shaft centers coincide with each other, the swing shaft 21 is inserted simultaneously. The swing shafts 21L and 21R are fixed to the shaft support portions 20L and 20R, and the bearing frames are configured so that the track frames 17L and 17R can swing with respect to the swing shafts 21L and 21R.
The support frame 19 is fixed to the body side such as the transmission case 5 such that the central plate at the left and right center is fixed to the lower surface of the transmission case 5 by bolting, and the left and right end plates 19c and 19c are provided on the left final deceleration case 16L. And fixed to the right final deceleration case 16R. That is, on the final deceleration case 16L, 16R side, bolt fastening screw holes 16a, 16a are formed on the outer side, and bolt fastening screw holes 16b are formed on the inner side, respectively, and the end plate 19c of the spindle frame 19 is formed. The outer connection block 22a and the inner connection block 22b, which are bolted and fixed to the upper surface, can be firmly fixed by bolting using the screw holes 16a and 16b.
As for the connection block, the outer connection block 22a side is wide and includes two bolt insertion holes 22c and 22c for the final deceleration case 16, and two bolt insertion holes 22d and 22d for the end plate 19c. On the other hand, the inner connecting block 22b side has a narrow width (1/2 of the outer connecting block 22a) and a single bolt insertion hole 22e for the final deceleration case 16 and a single bolt insertion hole 22f for the end plate 19c. . Here, for example, when designing the outer connecting block 22a into a shape that allows the inner connecting block 22b to be obtained by dividing the outer connecting block 22a into the left and right parts, one of the connecting blocks 22a is formed by casting, and one of the connecting blocks 22a is cut into the left and right parts. Thus, two connecting blocks 22b and 22b can be obtained. In this embodiment, two outer connecting blocks 22a and two inner connecting blocks 22b are required for fixing the spindle frame 19 to the left and right final deceleration cases 16L and 16R. This can be done by forming three blocks 22a. As described above, by using the connection blocks 22a and 22b having similar shapes, it is possible to reduce the cost of manufacturing materials and reduce assembly errors. In the embodiment, casting production is taken as an example, but the same effect can be obtained by sheet metal forming.
The connecting blocks 22a and 22b form a steeply inclined surface 22x and a gently inclined surface 22y, and can prevent accumulation of scattered mud during running.
The track frames 17L and 17R that are slidably coupled to the support frame 19 have upper frame portions 17d and 17e that contact the plate members 19a and 19b at the shaft support portions 20L and 20R of the support frame 19, respectively. It is configured to be capable of swinging within the applicable range. In this embodiment, the swing range is set by providing notches 19g and 19g at corresponding portions of the front and rear plate members 19a and 19b of the support frame 19.
The support structure of the front and rear extending wheels 11 and 12 and the idler wheel 13 with respect to the track frames 17L and 17R will be described in detail. As described above, the track frame 17 includes the swing boss portion 17b, the front pedestal 17f for attaching the front side extension wheel 11, the rear side pedestal 17r for attaching the rear side extension wheel 12, and the idler wheels 13, 13. Are composed of a lower frame 17c for supporting the upper and lower frame portions 17d, 17e and the like that can hold the swing boss portion 17b. A sub-frame 24 is provided in front of the front pedestal 17f, and a front tensioning wheel 11 is mounted via an urging adjustment means S. In each case, a sub-frame 24 is configured by using a sheet metal material and including an inclined main bracket 24a corresponding to the front pedestal 17f, a lower horizontal base 24b, and a sub bracket 24c parallel to the inclined main bracket 24a.
As for the urging adjustment means S, an inclined cylindrical body 25 having a rectangular cross section by sheet metal molding is integrally formed on the subframe 24 by welding. Further, an inner sliding cylindrical body 26 is provided so as to be slidable on the inclined cylindrical body 25 in an inscribed state.
Here, the inclined cylindrical body 25 is formed into a rectangular tube shape by a main body portion formed by bending a sheet metal material into a U shape and a bottom portion which welds and connects the left and right lower ends of the main body portion, and one end side is formed into the sub-tube. It is integrated with the sub bracket 24c of the frame 24 by welding. On the other hand, the inner sliding body 26 is also formed into a rectangular tube shape with a main portion formed by bending a sheet metal material into a U shape and a bottom portion where the left and right lower ends of the main portion are connected by welding. One end of the inner sliding body 26 is connected to the tensioning wheel bracket 32.
The inner sliding cylinder 26 includes a spring 27, an adjustment shaft 28, and an adjustment bolt 29 that contacts the head of the adjustment shaft 28. One end of the adjustment shaft 28 is fixedly supported by a fixing nut 30 at the base end portion of the tensioning wheel bracket 32, and the inner sliding cylinder 26 is moved with respect to the inclined cylindrical body 25 by the rotation of the adjustment bolt 29. The relative position is changed and set by sliding. Thus, the tension adjusting means S that can adjust the tensioning wheel 11 back and forth in the oblique direction and adjust the tension of the rubber crawler 14 is configured.
In addition, since the spring 27 is interposed between the spring seat plate 31 integral with the adjustment shaft 28 and the base end side of the tensioning wheel bracket 32, a sudden impact acting on the tensioning wheel 11 can be reduced.
The tensioning wheel 11 has a pair of left and right, and the tensioning wheel bracket 32 is interposed at an intermediate portion thereof, and the pair of tensioning wheels 11 and 11 are provided to be rotatable around a tensioning wheel shaft 32a. .
Between the inclined main bracket 24a and the sub bracket 24c, reinforcing members 24d and 24d made of reinforcing sheet metal are provided in a connected state in a vertically parallel state by welding. In addition, trapezoidal or triangular reinforcing members 24e, 24e are connected by welding between the reinforcing member 24d and the lower surface of the inclined cylindrical body 25 and the horizontal base 24b for reinforcement.
The tool is attached to the adjustment bolt 29 by inserting the tool from the right side in FIG. 10A into the tool insertion holes 17g and 24f formed in the front base 17f of the track frame 17 and the inclined main bracket 24a. Thus, the adjusting bolt 29 can be rotated forward and backward. On the other hand, a lock nut 33 that restricts the rotation of the adjusting bolt 29 is provided. A tool that interlocks the rotation of the lock nut 33 is the reinforcing member 24d, 24d that connects the main bracket 24a and the sub bracket 24c. Can be inserted from the open portion formed between the upper and lower sides, and work can be easily performed.
Next, a tensioning wheel bracket 34 that supports the rear tensioning wheel 12 is fixed to the rear base 17r of the track frame 17. Further, three pairs of idle wheels 13, 13... Are mounted by idle wheel brackets 35, 35... Across the lower frame 17c of the track frame 17 and the horizontal base 24b of the sub frame 24, respectively.
Of the idler wheels, the foremost idler wheel 13 f is attached to the sub-frame 24. That is, in the connected state in which the subframe 24 is fastened with the bolts 24g, 24g..., The lower surface of the horizontal base 24b of the subframe 24 is flush with the lower surface of the lower frame 17c of the track frame 17. The idler wheel bracket 35 is fastened with bolts, and the idler wheel bracket 13f is used to provide the foremost idler wheel 13f. Also, two pairs of front and rear idlers 13m and 13r are provided on the lower frame 17c side of the track frame 17 via idler brackets 35 and 35, respectively.
The support structure of the idler wheel 13 with respect to the support shaft 36 of the idler wheel bracket 35 is common. A support shaft 36 is attached to the through hole 35a of the idler wheel bracket 35 via bearings 37, 37, and through holes 13b, 13b are provided in the central boss portions 13a, 13a of the pair of idler wheels 13, 13, respectively. The pair of one and the other idler wheels 13 and 13 are passed through the support shaft 36 from the inside and outside, and the nut 36b is tightened with the outside screw portion 36a. At this time, the inner side of the screw portion 36a is slightly larger in diameter and integrated with the idler wheels 13 and 13 by fitting portions 36c and 36c having an outer spline or serration structure. The center boss portion 13a of the idler wheel 13 is formed with two grease injection through holes 13c and 13d at substantially diagonal positions, that is, symmetrical positions with the axis of the support shaft 36 interposed therebetween. Since the idler wheels 13 are provided on the left and right sides of the idler wheel bracket 35 as described above, the grease injection through holes 13c and 13d are also formed in the left and right idler wheels 13 and 13, respectively. .
Both the grease injection through holes 13b and 13c are configured to be able to supply grease to the bearings 37 and 37 through the inner peripheral side passage 38a of the external overflow prevention seal material 38. Reference numerals 39 and 39 denote detachable plugs for closing the inlets of the grease injection through holes 13b and 13c.
As described above, since the grease injection through-holes 13b and 13c are arranged at the diagonal positions, it is possible to fill without unevenness compared to the case of providing a single through-hole. In addition, there is an effect that it is convenient for venting the air inside and that the grease filling state can be easily grasped by checking the grease overflow from the entrance of one of the through holes 13b or 13c. In addition, in the said Example, although comprised in the idler wheel 13, you may provide in the front and rear tension wheels 11 and 12.
Scrapers 40, 40... For scraping off mud adhering to the outer periphery of the ring body are provided on the front and rear portions of the front and rear stretched wheels 11, 12 and the idler wheel 13, or one of them.
The oscillating shaft 21 is arranged so as to be positioned immediately below the drive shaft 11 and oscillates within a preset oscillating range in accordance with the magnitude of the grounding resistance from the field scene. Is. Further, in the front view or the back view, the inner end of the rubber crawler 14 on the machine body side covers a part of the final deceleration case 16, that is, the outward shift of the upper frame portions 17d and 17e of the track frame 17. Used for small tractors that can be configured in small quantities. By configuring the amount of outward deviation to be small, the constraint on strength can be relaxed, and the cost can be reduced. Since the track frame 17 is configured to be covered with the rubber crawler 14, there is a risk of mud depositing around the rubber crawler 14, but the upper frame portions 17d and 17e are not formed in a flat plate shape but in a U shape in plan view. Therefore, the mud that is about to adhere to the vicinity of the track frame 17 can be discharged well downward from the gap space.
The combination structure of the rear axle case 15 and the final speed reduction case 16 integrated with the rear axle case 15 is made to be the same form on the left and right sides for easy manufacture. That is, the transmission case mounting side shape of the rear axle case 15 and the bolt mounting hole configuration are designed symmetrically with respect to the reference line X0 (FIG. 8), and a straight line connecting the axle center P of the final deceleration case 16 and the drive shaft center Q. Y is designed to have an angle θ with respect to a parallel reference line X existing on a plane including the reference line X0 (FIG. 7). When the left and right sides are removed and installed, the angle between the parallel axis X and the parallel reference line X connecting the axle center P and the drive shaft center Q is −θ.
Therefore, although the left and right replacement mounting does not change the axle position (height) in the rear axle case 15, the height position of the drive shaft 9 of the final deceleration case 16 corresponds to an angle 2θ (= θ − (− θ)). The height of the dimension to be changed can be changed (for example, 40 mm). The change of the vertical height by the left-right transfer mounting can be made to correspond to the difference in specifications so that the high side of the drive shaft 9 is used for a semi-crawler type tractor and the low side is used for a standard wheel (wheel) type tractor. it can.
In addition, this corresponds to the difference in specifications between the semi-crawler type tractor and the foil type tractor, but in the case of the wheel type specification, in addition to the change in the height of the drive shaft 9 as described above, Since it is not necessary to install, it is removed.