JP3401415B2 - Tractor traveling device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a traveling device for a tractor, and more particularly, to a tractor having a rear wheel of a crawler type so that a sufficient traction force can be exerted even in wetlands. , A so-called semi-crawler tractor traveling device. 2. Description of the Related Art A tractor of this type is disclosed in, for example, Japanese Patent Application Laid-Open No. 4-257778.
2. Description of the Related Art There is known a tractor having a crawler traveling mechanism in which a crawler is wound around a rear wheel and an idler wheel disposed behind the rear wheel. The crawler-type traveling device has an advantage that an effective driving force can be easily obtained with a wide ground contact area. However, in the above-mentioned publication, the crawler traveling mechanism has a fixed position. In the case of the semi-crawler type, which has a shorter ground contact length than the full crawler type such as a combine, etc., depending on the unevenness of the ground and the degree of ups and downs, it is predicted that a sufficient ground contact area cannot be obtained due to the fact that most of one crawler floats in the air etc. You. Therefore, it is considered effective to secure the necessary traction force with a sufficient ground contact area to improve the road surface followability by making the crawlers pitchable. In the above tractor, it seems reasonable to use the rear axle also as a pitching fulcrum. However, in order for the crawler to withstand all ground contact loads acting on one location of the rear axle, the rear axle must be used. It is necessary to make the strength stronger than it is now, and after all, a large design change of the rear wheel transmission system, the rear axle case, and the like is forced, which is not very advantageous. An object of the present invention is to support the crawler traveling mechanism in a freely pitchable manner without changing the rear wheel transmission system. [0005] A first aspect of the present invention is a tractor traveling device, wherein a pair of left and right crawlers having a pair of left and right steerable front wheels and a driving sprocket mounted on a rear axle is provided. A track mechanism that rotatably supports a plurality of wheels in the crawler travel mechanism, and a support mechanism that supports the rear axle case so as to be able to pitch around the left and right axes. An arm part extending obliquely upward from the track frame and toward the inside of the drive sprocket, and a boss part integrally attached to the lower surface of the rear axle case are rotatably fitted on the left and right axes. while if, viewed from the rear to provide a reinforcing member for connecting the right and left of the boss portion to each other
To form a vertical loop-shaped support frame . According to the first aspect of the present invention, the track frame is supported in a freely pitchable manner by fitting its arm to a boss mounted on the lower surface of the rear axle case. The rear axle case can be sufficiently supported. The pitching fulcrum of the track frame should be close to the rear axle so that the change in crawler length due to pitching is not as noticeable as possible, so the boss is located inside the drive sprocket and tends to move left and right with the track frame, The boss receives not only an upward load but also a considerable bending moment. Therefore, the lower surface of the rear axle case and the boss are aligned.
A reinforcement member that attaches to the body and connects the left and right bosses
To form a vertical loop support frame in rear view.
So that, enough to withstand supported the bending moment in the vertical direction load
With the holding strength, each boss is attached to the fuselage with a wide span in the left-right direction, and the track frame can be sufficiently supported. For example, in order to have the support strength only by the boss portion, each boss portion needs to be a wide and thick structure and is likely to be heavy. It is possible to [Effect] As a result, the left and right boss portions are connected to each other and attached to the lower surface of the rear axle case, so that the pitching fulcrum of the track frame can be sufficiently supported without a large change in the rear wheel transmission system. It was possible to obtain a compact and lightweight semi-crawler type tractor traveling device while having a small and lightweight construction. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIGS. 1 and 2, a pair of left and right front wheels 19 and a pair of left and right rear wheels 14 which can be steerably operated.
A four-wheel drive agricultural tractor is provided with an engine 1 at the front of the body supported by a dashed line (see a two-dot chain line in FIG. 1) and a cabin 9 at the rear of the body covering the steering section. FIG. 2 shows the inside of the transmission case 8, in which power from the engine 1 is transmitted to the PTO shaft 4 via the transmission shaft 2 and the hydraulic multi-plate PTO clutch 3. The power from the engine 1 is supplied by a hydraulic multi-plate type forward clutch 5.
(Or hydraulic multi-plate reverse clutch 6 and transmission shaft 20),
Cylindrical shaft 7, first main transmission 10, second main transmission 11,
The power is transmitted to the left and right rear wheels 14 via the auxiliary transmission device 12 and the rear wheel differential device 13. The power branched immediately before the rear wheel differential device 13 is transmitted to the left and right front wheels 19 via the transmission shaft 15, the hydraulic clutch type front wheel transmission device 16, the transmission shaft 17, and the front wheel differential device 18. The first main transmission 10 is of a hydraulic clutch type in which four hydraulic multi-plate type first speed clutches 21, second speed clutches 22, third speed clutches 23 and fourth speed clutches 24 are arranged in parallel. The gear can be shifted to 4 speeds, 1st to 4th
By operating one of the speed clutches 21 to 24 to the transmission side, the power from the cylindrical shaft 7 is shifted to four speeds and transmitted to the lower transmission shaft 25. The second main transmission 11 is of a hydraulic clutch type in which two hydraulic multi-plate low-speed clutches 26 and high-speed clutches 27 are arranged in parallel, and one of the low-speed and high-speed clutches 26, 27 is used. By operating on the transmission side, the motive power from the transmission shaft 25 is transmitted to the auxiliary transmission 12 on the lower side by performing a speed change operation in two stages. Auxiliary transmission 12
Is of a synchromesh type that slides the shift member 53 and can be shifted in two stages. Next, a hydraulic clutch type front wheel transmission 1
6 will be described. As shown in FIGS. 3 and 2, a transmission shaft 28 and a transmission shaft 15 connected to the transmission shaft 17 are arranged concentrically, and a first transmission gear 29 fixed to the transmission shaft 28 and a transmission shaft A hydraulic multi-plate type standard clutch 45 is provided between the first clutch 15 and the second clutch 15. An opening 33 is formed in the transmission case 8, a transmission case 34 is connected to the opening 33, and a first bypass transmission shaft 35 is supported by the transmission case 34. A third transmission gear 30 is fitted to the transmission shaft 15 so as to be relatively rotatable, and a hydraulic multi-plate type speed increasing clutch 46 is provided between the transmission shaft 15 and the third transmission gear 30. First speed increasing gear 31 fixed to first bypass transmission shaft 35
The second speed increasing gear 32 is engaged with the first transmission gear 29 and the second transmission gear 30. As shown in FIG. 5, a control valve 37 for supplying and discharging hydraulic oil from a pump 36 to standard and speed increasing clutches 45 and 46 is provided. The standard position 37A where the standard clutch 45 is supplied to operate the transmission side, the speed increasing clutch 46 is drained to be operated to the transmission cutoff side, and the operating oil is supplied to the speed increasing clutch 46 to move the speed increasing clutch 46 to the transmission side. And a neutral position 37N for operating the standard clutch 45 in the oil-discharged state and operating it on the transmission cutoff side, and operating the standard and speed-increasing clutches 45 and 46 in the oil-discharged state and operating it on the transmission cutoff side. The neutral position 37 is set by a spring.
It is energized to N. An angle sensor 38 for detecting a steering angle of the front wheel 19 from the straight traveling position A is provided, and a detection value of the angle sensor 38 is input to a control device 39. With the above structure, the arm 56 is connected to the detection switch 57 attached to the transmission case 34 as described later.
When the steering angle of the front wheel 19 is within the range of the right and left set angles B from the straight-ahead position A in a state in which the contact signal a contacts the ON signal of the detection switch 57 to the control device 39, the control is performed. The control valve 37 is operated to the standard position 37A by the operation signal from the device 39, the standard clutch 45 is operated to the transmission side, and the speed increasing clutch 46 is operated to the transmission cutoff side. Thereby, as shown in FIGS. 2 and 3, the power of the transmission shaft 15 is transmitted to the front wheel 19 via the standard clutch 45, the first transmission gear 29 and the transmission shafts 28 and 17, and the peripheral speed of the front wheel 19 and the rear wheel 14 is a standard state in which the peripheral speed is substantially equal. Next, as in the case of turning on a ridge, for example, the front wheel 19
When the steering angle exceeds the range of the right and left set angles B from the straight traveling position A, the control valve 37 is operated from the standard position 37A to the speed increasing position 37B by the operation signal from the control device 39, and the speed increasing clutch is operated. 46 is operated to the transmission side, and the standard clutch 45 is operated to the transmission interruption side. As a result, FIG.
As shown in FIG. 3, the power of the transmission shaft 15 is transmitted to the front wheel 19 via the speed increasing clutch 46, the second transmission gear 30, the first bypass transmission shaft 35, the first transmission gear 29, and the transmission shafts 28 and 17. , The peripheral speed of the front wheel 19 becomes higher than the peripheral speed of the rear wheel 14. The state shown by the two-dot chain line in FIGS. 2 and 1 is a wheel running state in which the rear wheel 14 is attached to the rear axle 40 of the transmission case 8. In this agricultural tractor, the state shown by the solid line in FIG. Remove the rear wheel 2 from the axle 40, and
The crawler traveling state in which a pair of left and right crawler traveling devices 41 are attached to the vehicle is set to be zero. The crawler traveling device 41 includes a driving sprocket 42,
It is composed of a driven wheel 43, a driven wheel 44, a track frame 47 supporting the driven wheel 43 and the driven wheel 44, a crawler 48, and the like. In the crawler traveling state in which the crawler traveling device 41 is attached to the rear axle 40, the rear axle 4
The track frame 47 is swingable back and forth around a left and right axis P1 of a support frame (not shown) extending to around 0 via a support bracket (an example of an arm) 47a of the track frame 47. , And the drive sprocket 42 is directly mounted on the rear axle 40. In this manner, in the crawler traveling state in which the crawler traveling device 41 is attached to the rear axle 40, the contact position of the rolling wheel 44 is set to be the same as the contact position of the rear wheel 14, and the rear axle 40 is attached to the rear axle 40. And the crawler traveling device 41 is attached, the height of the body is constant. As shown in FIGS. 3 and 2, the second bypass transmission shaft 49 is concentric with the first bypass transmission shaft 35 and the transmission case 34.
The transmission gear 50 of the transmission shaft 15 and the transmission gear 51 of the second bypass transmission shaft 49 are engaged with each other, and the cylindrical connecting member 52 is slidable on the spline portion of the second bypass transmission shaft 49. Fitted outside. A shift fork 55 containing a detent mechanism 55a is externally slidably fitted on a support shaft 54 fixed to the transmission case 34, and the shift fork 55 is engaged with the connecting member 52. As shown in FIGS. 3 and 4, the transmission case 3
The operation shaft 56 is supported so as to penetrate the transmission case 4, and the arm 56 a fixed to the operation shaft 56 inside the transmission case 34 engages with the base of the shift fork 55, and the operation is performed outside the transmission case 34. Arm 56b on shaft 56
Has been fixed. Thus, by operating the arm 56b upward and downward from outside the transmission case 34, the shift fork 55 is slid and the connecting member 5
2 can be slid. With the above structure, when the rear wheel 14 is mounted on the rear axle 40 as shown by the two-dot chain line in FIG. 2 and FIG. 1, the arm 56 as shown by the two-dot chain line in FIG.
b, the connecting member 52 is slid rightward on the paper surface by the shift fork 55 to separate the connecting member 52 from the first bypass transmission shaft 35 as shown in FIGS. When the bolt 58 is
Fix with. As a result, the power of the transmission shaft 15 is transmitted through the standard and speed increasing clutches 45 and 46 of the front wheel transmission 16,
In this state, the arm 56a comes into contact with the detection switch 57 attached to the transmission case 34, and the detection switch 57 is turned off.
The N signal is input to the control device 39. In the state where the ON signal of the detection switch 57 is input to the control device 39, the steering angle of the front wheel 19 is within the range of the right and left set angles B from the straight traveling position A as described above. Then, the control device 37 operates the control valve 37 to the standard position 37A, and the standard clutch 45
Is operated to the transmission side, the speed increasing clutch 46 is operated to the transmission interruption side, and power is transmitted to the front wheels 19 in a standard state where the peripheral speed of the front wheels 19 and the peripheral speed of the rear wheels 14 are substantially equal. When the steering angle of the front wheel 19 exceeds the range of the right and left set angles B from the straight traveling position A in a state where the ON signal of the detection switch 57 is input to the control device 39, the control device 39 is controlled. , The control valve 37 is operated from the standard position 37A to the speed increasing position 37B, the speed increasing clutch 46 is operated to the transmission side, the standard clutch 45 is operated to the transmission shut off side, and the peripheral speed of the front wheel 19 is reduced to the rear wheel 14. Power is transmitted to the front wheels 19 in a speed-up state in which the speed is higher than the peripheral speed of the front wheel 19. Next, as shown by the solid line in FIG.
In the crawler traveling state in which the crawler traveling device 41 is attached to the vehicle, the arm 56b is operated downward as shown by the solid line in FIGS. The member 52 is connected across the first and second bypass transmission shafts 35 and 49 and
The bolts 58 are fixed while b is operated downward. As a result, the power of the transmission shaft 15 is transmitted to the transmission shaft 28 via the second bypass transmission shaft 49 and the first bypass transmission shaft 35. In this state, the arm 56a is separated from the detection switch 57. Therefore, the ON signal of the detection switch 57 is not input to the control device 39. In the state where the ON signal of the detection switch 57 is not input to the control device 39, no operation signal is transmitted from the control device 39 to the control valve 37 in any state. The control valve 37 is always held at the neutral position 37N by the urging force of the spring,
6. Both the standard and speed increasing clutches 45, 46 are operated on the transmission cutoff side. In this case, as shown by a two-dot chain line in FIGS. 5 and 4, the arm 56b is operated upward and the connecting member 52 is slid to the right on the paper by the shift fork 55 so that the arm 56a comes into contact with the detection switch 57. In this state, if the ON signal of the detection switch 57 is not input to the control device 39 due to an abnormality such as disconnection, the control valve 37 is held at the neutral position 37N. As shown in FIG. 1, the outer diameter of the rear wheel 14 is
Since the outer diameter of the drive sprocket 42 of the crawler traveling device 41 is smaller, the crawler traveling device is less than the peripheral speed of the front wheel 19 (the peripheral speed of the rear wheel 14) in the standard state of the front wheel transmission device 16. The peripheral speed of 41 (the speed of the crawler 48) is lower. In this case, the power from the transmission shaft 15 is reduced by the transmission gears 50 and 51 shown in FIGS. 2 and 3 and transmitted to the first bypass transmission shaft 35 and the front wheel 19, and the peripheral speed of the front wheel 19 and the crawler traveling device 41 Is configured to be substantially equal to the peripheral speed (the speed of the crawler 48). Therefore, the first and second main transmissions 10, 1
1. When comparing the traveling speed of the body of the sub-transmission 12 at each shift position, the crawler traveling with the crawler traveling device 41 attached to the rear axle 40 is better than the wheel traveling state where the rear wheel 14 is attached to the rear axle 40. In the state, the traveling speed of the aircraft is generally lower. Next, the support structure of the crawler traveling mechanism 41 will be described. As shown in FIGS. 6 and 7, the support bracket 47 extends upward from the track frame 47 and in an oblique direction toward the inside of the drive sprocket 42.
The shaft member 61a and the boss portion 60 attached to the lower surface of the rear axle case 59 are rotatably fitted at the left and right axis P1, and the reinforcing member 62 connects the left and right boss portions 60, 60 together. Are provided to constitute a support mechanism C for pitching and supporting the track frame 47. Each of the bosses 60 is mounted on a board 63 to be bolted on the lower surface of the rear axle case 59 by two stays 63a, 63a.
3b, and both stays 63a, 63
The reinforcing member 62 is provided in a state of being fixed to 3b. That is, the left and right bosses 60, 60 and the left and right substrates 6
3, 63 and the reinforcing member 62 are mounted on the rear axle case 59 in an integrated state, and together form a vertical loop-shaped support frame f in rear view. With this structure, the boss portion 60 itself is a small part having a narrow left-right width and is a compact fitting portion having a short fitting length with the track frame 47, and has sufficient supporting strength to withstand a vertical load and a bending moment. I have. A regulating mechanism 64 for regulating the pitching range of the track frame 47 is provided in front of the support frame f.
Is provided. Briefly, as shown in FIGS. 6 and 8, a guide member 65 having upper, lower, left and right wall surfaces is supported inside the front portion of the track frame 47.
A regulating mechanism 64 is configured by fixing a bracket 67 provided with a roller member 66 that enters the apparatus 5 to the body side. That is, the contact between the upper wall surface 65a, the bottom wall surface 65b, and the roller member 66 of the guide member 65 causes the crawler traveling mechanism 41 to pitch within a predetermined angle range.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an overall side view of an agricultural tractor in a crawler running state. FIG. 2 is a schematic view showing a transmission system in a transmission case in a wheel running state. FIG. 3 is a crawler running state. FIG. 4 is a longitudinal side view of the vicinity of the front wheel transmission. FIG. 4 is a side view of the outside of the transmission case in the crawler traveling state. FIG. FIG. 7 is a plan view showing the support structure of the frame. FIG. 7 is a rear view of a partially cutaway showing the structure of the support mechanism. FIG. Rear axle 41 Crawler traveling mechanism 42 Drive sprocket 47 Track frame 47a Arm 59 Rear axle case 60 Boss 61 Shaft 62 Reinforcement member C Supporting mechanism P1 Left and right axis

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B62D 55/02 B62D 49/00

Claims (1)

(57) [Claim 1] A pair of left and right steerable front wheels (19),
A pair of left and right crawler traveling mechanisms (41) having a driving sprocket (42) attached to the rear axle (40);
The plurality of wheels (4) in the crawler traveling mechanism (41)
Track frame (47) for rotatably supporting 4)
Mechanism (C) for supporting the rear frame member (59) so as to be pitchable about the left and right axis (P1), and the support mechanism (C) is connected to the track frame (47).
Arm part (47a) extending upwardly and obliquely toward the inside of the driving sprocket (42).
And a boss (60) integrally attached to the lower surface of the rear axle case (40), which is rotatably fitted at the left-right axis (P1). vertical Lou viewed from the rear provided with a reinforcing member that connects (62) the
A traveling device for a tractor having a support frame in the form of a tractor.