JP2007118907A - Crawler type tractor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small sized rear-wheel-drive crawler type tractor at low cost. <P>SOLUTION: The small-sized crawler type tractor is equipped with a crawler type traveling device which has a crawler frame rotatably supporting a driven idler on both ends, and a drive sprocket mounted to a rear axle case, and wherein a crawler is wound between the driven idler and the drive sprocket at the lower part of the upper part vehicle body. In this case, the crawler frame is fixedly provided on the upper part vehicle body by at least two support members, and the fixedly provided place is further at the rear part of the vehicle than the tip end part of the crawler type traveling device. The crawler type traveling device can be fixedly provided on the upper part vehicle body by only support member, total weight can be reduced, and the turning property can be improved. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a crawler tractor, and more particularly, to a crawler tractor that can be easily manufactured using a common part with a wheel tractor.

  FIG. 7 is a perspective view of a conventional small wheel tractor 97. The tractor 97 is a rear-wheel drive four-wheel vehicle. Generally, such a wheel-type tractor includes a hydraulic operation driven cultivation operation attachment, an attachment for culling, an attachment for soil disinfection, an attachment for creating a cultivation floor, and a seed potato. In general, work machines such as planting attachments and multi-work attachments are attached. However, since the wheel-type tractor 97 has a high ground pressure, the traveling performance on soft or rough terrain may not be sufficient, and particularly in the case of a small tractor, the traction force may not be sufficient due to its small size. In such a case, if the wheel-type tractor 97 can be improved to a small crawler tractor, the contact pressure can be reduced, so that it is possible to improve the running performance on soft or rough terrain, and at the same time, the traction force can be increased.

  As such a technique, for example, there is one that improves a new crawler tractor by sharing a steering mechanism of a wheel tractor (Patent Document 1). The patent document 1 describes the difference between the crawler type and the wheel type turning mechanism, that is, when the wheel type tractor is modified to the crawler type, the brake device on one side is operated by depressing either the left or right brake pedal inside the turning. It was made in view of the fact that the turning operability was not good if the driving sprocket on one side was braked and the crawler inside the turning was decelerated to turn the vehicle body. An object of the present invention is to make it possible to turn the body of a crawler tractor and to reduce costs by sharing components using a steering mechanism provided in a wheel tractor.

  A wheeled work vehicle can run if the wheel is in contact with the ground even if the balance is somewhat poor, whereas a crawler type work vehicle may have insufficient traction because the front end of the crawler is lifted. Further, since the crawler tractor is mainly used for wet fields, it is necessary to set the ground clearance high. A technique for adjusting the tractor front-rear balance and ground clearance with a simple and inexpensive configuration has already been disclosed (Patent Document 2). The patent publication 2 discloses a tractor including a left and right crawler type traveling device in which a crawler is mounted between a drive sprocket and a driven idler, and a crawler frame that supports the drive sprocket and the driven idler is provided as a vehicle frame. On the other hand, a crawler tractor is disclosed in which the attachment position can be adjusted in the front-rear direction and / or the vertical direction. The crawler type tractor disclosed in the Patent Publication 2 is presumed that the tractor portion is intended for a medium-sized or large-sized tractor, and the tip of the support member for attaching the crawler frame that supports the drive sprocket and the driven idler to the vehicle The crawler type traveling device is attached to the lower part of the tractor in front of the front end.

  On the other hand, a technique for simplifying the drive system of a small crawler tractor and improving turning performance has been developed particularly for medium and large tractors (Patent Document 3). For example, Patent Document 3 discloses a front-wheel drive crawler tractor in which a hydraulic transmission turning mechanism (turning HST mechanism) for turning the airframe is connected to a drive system behind a forward / reverse switching mechanism for moving the airframe back and forth. A small crawler tractor is disclosed in which the turning HST mechanism is divided into a variable displacement pump and a constant displacement motor, and the constant displacement motor is connected to the input shaft of the planetary gear type differential mechanism. This tractor is connected to the variable displacement pump with the output after the sub-shift of the traveling speed change mechanism, and makes the turning radius constant by making the vehicle speed and the rotation of the steering motor proportional to each other. It can be secured.

In addition, the mission structure and axle case are integrated as a crawler-type tractor with improved work structure that is lightweight, simple, low-cost, and has a good balance between front and back and easy handling even when the overall length is short. There is also disclosed a front-wheel drive crawler tractor in which a transmission case is supported by a front and rear connecting frame that is horizontally mounted between a pair of left and right crawler traveling devices, and an axle case is disposed in front of the connecting frame (patent) Reference 4).
JP 2000-159143 A JP 2002-145134 A JP 2004-17841 A JP 2004-66913 A

  As described above, the crawler-type tractor has a low ground pressure, so that it is suitable for work in a wet field and can increase the traction force of the work machine. However, as shown in Patent Document 1, the driving wheel of the wheel-type tractor is simply used. When using as a drive sprocket, it may not be possible to secure a ground clearance suitable for work in wet fields. In particular, since the crawler tractor is required to adjust the left / right and up / down balance more strongly, it is convenient if such control can be adjusted more easily. In this case, as in Patent Document 2, an attachment hole is made in the crawler frame, and an attachment hole corresponding to the attachment hole is made in the vehicle frame, and these are fixed by shifting in the front-rear and vertical directions. In this method, there are many fixing points and the operation is complicated. In addition, since the crawler tractor is heavier than the wheels, the left and right crawler traveling devices tend to be heavier in total weight, and the need for weight reduction is strongly desired.

  In addition, even in the case of a small crawler tractor, it is preferable to ensure an excellent operation feeling as in the case of a medium or large crawler tractor. However, the hydraulic transmission mechanism for steering that turns the aircraft, the forward / reverse switching mechanism that makes the aircraft move forward and backward, the variable displacement pump of the hydraulic transmission mechanism for turning, etc. that are used to improve the turning feeling are simply small. It is structurally difficult to divert to a crawler tractor. In particular, the crawler tractors described in Patent Document 3 and Patent Document 4 are front wheel drive systems in which a front axle case is provided separately from the transmission in the lower front part of the engine, and the structure of the rear wheel drive system is as follows. Different. Accordingly, it is not easy to manufacture a small rear wheel drive crawler tractor at a low cost by utilizing the basic structure of a small wheel drive tractor.

  Therefore, the present invention utilizes the structure of a small wheel type tractor driven by a rear wheel as much as possible, is excellent in operation feeling, can secure a ground height suitable for a wet field, and can easily adjust the vertical and horizontal balance. A tractor is provided.

  The inventors of the present invention can manufacture a small crawler tractor at a low cost by sharing the basic structure of a small wheel tractor when manufacturing a small crawler tractor, and in this case, a crawler frame that rotatably supports driven idlers at both ends. Has been found to be able to efficiently maintain the strength by fixing it to the upper vehicle body with at least two support members, and the present invention has been completed.

  According to the present invention, since the common part provided in the wheel type tractor is used, the small crawler type tractor can be manufactured at low cost by using the main body of the small type wheel tractor. In addition, compared with a wheel tractor, it has a large force for towing a farm working machine, and is excellent in traveling performance on soft or rough terrain.

  In addition, since the driven idler is rotatably supported at both ends of the crawler frame, the minimum ground clearance of the crawler tractor can be secured.

  In addition, it is possible to secure an excellent weight balance by devising the arrangement of the drive system, so that it can be fixed at two locations behind the tip of the crawler type traveling device, and at the same time the ground pressure of the crawler is lowered. It can be secured.

  Furthermore, since the crawler frame is fixed to the upper vehicle body by at least two support members, the weight can be further reduced, and the crawler type traveling device can be easily attached.

  A first aspect of the present invention includes a crawler frame that rotatably supports a driven idler at both ends, and a drive sprocket attached to a rear axle case, and the crawler is wound between the driven idler and the drive sprocket. In the small crawler type tractor provided with the crawler type traveling device at the lower part of the upper vehicle body, the crawler frame is fixed to the upper vehicle body by at least two support members, and the fixed position is the same as that of the crawler type traveling device. A small crawler tractor characterized by being behind the vehicle from the tip.

  The crawler type truck of the present invention is a crawler type tractor that can be manufactured using the structure of a wheel type tractor as much as possible, and in particular, a rear wheel that can be manufactured by using a small wheel type tractor driven by a rear wheel. It is a drive crawler tractor.

  As shown in FIG. 1, the crawler type tractor according to the present invention has a driven sprocket rotatably supported by both ends of a crawler frame and a drive sprocket mounted on a rear axle case fixed to the crawler frame, This is a so-called rear wheel drive crawler tractor having a crawler type travel device in which a crawler is wound between a sprocket and the drive sprocket at the lower part of the upper vehicle body. Since the driven idlers are arranged at both ends of the flora frame, the driving sprocket is arranged at the upper portion of the driven idler, and a high ground clearance of the driving sprocket can be ensured. The crawler frame is fixedly provided by the upper vehicle body and at least two support members. Because it is fixed with such a small number of members, the left and right crawler type traveling device can be easily attached to the upper vehicle body and separation is easy, and the weight balance can be changed due to an optional device added to the upper vehicle body. Accordingly, it can be easily moved back and forth.

  Since the fixed position between the upper vehicle body and the left and right crawler type traveling devices is determined by the weight balance with the upper vehicle body, when the upper vehicle body is small, a support member is provided on the pair of left and right crawler frames (81L, 81R). The upper vehicle body can be attached simply by mounting and fixing the upper vehicle body (90) via (87R, 87L, 84R, 84L). However, the strength cannot be maintained by fixing the crawler frame to only one place. Therefore, it is fixed by at least two support members. In this case, in the present invention, in addition to the fixing portion between the upper vehicle body and the crawler frame, the upper vehicle body is fixed to the upper vehicle body by a support member at the rear of the vehicle from the front end portion of the crawler type traveling device. Conventionally, as described in, for example, Japanese Patent Application Laid-Open No. 2002-2523, the upper vehicle body is fixed by a support member that extends to the front of the vehicle body rather than the crawler type traveling device. By adjusting the weight balance by devising the arrangement of the drive system and the like, it can be fixed to the upper vehicle body by a support member behind the front end of the crawler type traveling device. Moreover, it has an excellent center of gravity balance.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings. 1 is a side view of a small crawler tractor according to an embodiment of the present invention, FIG. 2 is a perspective view of a traveling portion of the tractor, FIG. 3 is a sectional plan view of the tractor, and FIG. 4 is a drive portion of the tractor. FIG. 5 is a perspective view of the frame structure of the crawler traveling device, FIG. 7 is a perspective view of a conventional wheel type tractor, and FIG. It is a figure explaining ratio of the grounding length (L2) of the said crawler traveling apparatus with respect to the full length (L1) of an upper vehicle body.

(1) Upper Vehicle Body and Crawler Type Traveling Device As shown in FIG. 1, a small crawler type tractor (airframe 1) according to the present invention includes an upper vehicle body 90 located above the airframe 1 and a crawler type traveling located below. A bonnet 2 that covers an engine (not shown) and a driver's seat 4 for maneuvering the fuselage 1 are disposed behind the bonnet 2 in front of the upper vehicle body 90. A steering handle 9 for operating the airframe 1 is disposed in front of the driving cabin 4, a seat 8 is provided at the rear, and the left and right sides of the seat 8 are used for operating the airframe and raising / lowering the work equipment. A main transmission lever (not shown), an auxiliary transmission lever (not shown), a PTO operation lever (not shown), and the like are provided. Further, in order to protect the driver when the fuselage rolls over, four safety frames are formed so as to cover the entire driver seat 4. In addition, a work machine 6 that can be removed according to work can be attached to the rear of the upper body 90. In the agricultural tractor according to the present invention, the front frame 100 is disposed at the lower part of the vehicle.

  As shown in FIG. 2, the crawler traveling device 80 includes two left and right crawler frames 81L and 81R extending in the traveling direction, and two front and rear side frames 82 connecting the crawler frames 81L and 81R. 83, and a driven idler 85 is rotatably supported at the front and rear ends of the crawler frames 81L and 81R, respectively, and a plurality of equalizer wheels 86 are rotatable between the two driven idlers 85R and 85F. It is supported by. A drive sprocket 60 is disposed above the two driven idlers 85R and 85F and the equalizer wheel 86, and the line connecting the two driven idlers 85R and 85F is defined as the base. The crawler belt 95 is wound in a substantially triangular shape to form a crawler type traveling device 80. In the present invention, driven idlers are arranged at both ends of the crawler frame. However, as shown in FIG. 2, a driven idler 85R may be connected to the crawler frame 81L via a connecting member 85 ′. The crawler frame may be curved without being limited to a straight line, or may be bent forward as shown in FIG. 2 and connected to the tip of the driven idler 85F. In the figure, 84 (R, L) and 87 (R, L) are support members that connect the crawler frame 81 and the upper vehicle body 90.

  In the present invention, the left and right crawler frames are fixed to the upper vehicle body 90 by at least two support members, respectively, and the fixed position is behind the vehicle from the tip of the crawler type traveling device 80. For example, as shown in FIG. 6, support members 87R, 87L, 84R, and 84L are arranged from the front and rear of the crawler frame 81L upward, and are fixed to the upper vehicle body 90, respectively. Although there is no limitation on the fixed position of the upper vehicle body 90, for example, the support members 87R and 87L7 can be fixed to the side surface of the clutch housing of the upper vehicle body 90, and the support members 84R and 84L are attached to the rear axle cases 40L and 40R. Can be fixed. The fixing location of the upper vehicle body is not particularly limited, but in the present invention, the fixed location between the support members 87R, 87L, 84R, 84L and the upper vehicle body 90 is from the tip of the crawler type traveling device 80 to the vehicle. Can be fixed to a structure such as a clutch housing disposed at the top of the crawler type traveling device 80 simply through a support member, and a special fixing point is provided at the lower part of the upper vehicle body. There is no need. For this reason, the total weight of the vehicle can be reduced.

  Further, in the present invention, as shown in FIG. 8, the contact length (L2) of the crawler traveling device with respect to the total length (L1) of the upper vehicle body, that is, L2 / L1 is 0.5 or more. Since the total weight of the vehicle is reduced as described above, the contact pressure can be kept low even when the contact length of the crawler traveling device is short, and the turning performance can be improved. Note that the total length (L1) of the upper vehicle body does not include the length of the work implement attached to the front portion or the rear portion.

  In the crawler tractor of the present invention, the crawler frame is fixed to the upper vehicle body by fixing the support members (87R, 87L) to the upper vehicle body with bolts and the support members (84R, 84L) as shown in FIG. The rear axle cases 40L and 40R are preferably fixed with bolts. This is because if the bolt is used, the grounding point can be easily changed according to the change in the weight balance without using a new fixture.

(2) Traveling system The small crawler tractor according to the present invention includes a gear-switching traveling speed change mechanism that shifts the speed by switching gears, and has the body in the drive system behind the forward / reverse switching mechanism that moves the body back and forth. A hydraulic transmission mechanism including a steering HST turning pump and a HST turning motor for turning is coupled. For example, as shown in FIG. 3, the driving force from the engine 3 is shifted by a main auxiliary transmission 39 that is a gear-switching traveling transmission mechanism disposed in the transmission case 23, and then the left and right rear axle cases 40L. , 40R, the axle 89 that drives the drive sprockets 60L, 60R of the crawler type traveling device 80 is rotated.

  At this time, the HST turning pump 72 for turning the airframe 1 to the drive system behind the forward / reverse switching mechanism 7 for moving the airframe 1 forward and backward, and the HST turning motor 73 are respectively connected to the side of the mission case 23 and the mission. It is provided above the differential mechanism 50 </ b> L in the case 23.

(3) Power Transmission Mechanism As shown in FIG. 4, the output from the engine 3 is input from the output shaft 31 to the forward / reverse switching mechanism 7 via the clutch housing 5. In the forward / reverse switching mechanism 7, the gear 33 of the output shaft 31 meshes with the forward gear 32 provided on the main shaft 37 when the vehicle body 1 moves forward, while the output shaft 31 and the reverse gear 34 move when the vehicle body 1 moves backward. Are engaged with each other via the counter gear 36 of the reverse counter shaft 35, so that the machine body 1 is moved forward and backward. The power that has passed through the forward / reverse switching mechanism 7 is transmitted via the main shaft 37 to the main / sub transmission 39 that is arranged further rearward. The main shaft 37 and the main transmission shaft 41 located above the main shaft 37 are connected via four main transmission gears 42 having different numbers of teeth in the case of four main transmissions, for example. The main transmission gear 42 is always meshed with the main shaft gear 37 and rotated together. On the other hand, the main transmission gear 42 is loosely fitted on the main transmission shaft 41, and is selected by selectively fixing one of the four main transmission gears 42 on the main transmission shaft 41 by a main transmission lever (not shown). The main transmission shaft 41 is rotationally driven according to the number of teeth of the main transmission gear 42 that has been made.

  This driving force is transmitted from the two gears 62 located behind the main transmission shaft 41 and fixed on the main transmission shaft 41 to the auxiliary transmission shaft 45 via the auxiliary transmission gear 46. In the case of two sub-speeds, two sub-transmission gears 46 having different numbers of teeth are slidably formed on the sub-transmission shaft 45, and these two gears 46 are sub-shifted by a sub-transmission lever (not shown). By sliding back and forth on the shaft 45 and selectively meshing with any gear 62 on the main transmission shaft 41, power after the sub-shift is obtained.

  The power after the sub-shift is changed from the front-rear direction to the left-right direction via the bevel gear 47 located at the rear end of the sub-transmission shaft 45, and to the differential mechanisms 50L and 50R located at the rear of the mission case 23 described later. Entered. Next, power in the differential mechanisms 50L and 50R is transmitted to drive output shafts 59L and 59R that drive the sprockets 60L and 60R, and the sprockets 60L and 60R fixed to the other ends are rotationally driven.

(4) Differential Mechanism As shown in FIG. 5, the driving force of the auxiliary transmission shaft 45 is applied to a bevel gear 47 fixed to the rear end of the auxiliary transmission shaft 45 and a pinion shaft 22 meshing with the bevel gear 47. The pinion shaft 22 is driven to rotate via the fixed bevel gear 21. Next, the left and right gears 25L, 25R fixed to both ends of the pinion shaft 22 and the gears 27L, 27R fixed to one end of the left and right input shafts 20L, 20R mesh with each other, and the pinion shaft 22 rotates. Distribute to the left and right input shafts 20L, 20R. Further, the rotation of the left and right input shafts 20L and 20R is input to the sun gears 51L and 51R of the left and right planetary gear mechanisms 50L and 50R. The planetary gear mechanisms 50L and 50R include sun gears 51L and 51R fixed to the sun gear input shafts 20L and 20R, and planetary gears 53L and 53R provided around the sun gears 51L and 51R so as to freely revolve. The planetary gears 53L, 53R are supported by the sun gear input shafts 20L, 20R and the axles 59L, 59R. The carriers 55L, 55R are rotatably fitted to the outer periphery of the carriers 55L, 55R. Carrier gears 56L and 56R are formed. The planetary gears 53L and 53R mesh with drive output gears 58L and 58R fixed to the left and right drive output shafts 59L and 59R, and the drive output shafts 59L and 59R are rotated by the rotation of the drive output gears 58L and 58R. The sprockets 60L and 60R fixed to the other end are rotated.

  On the other hand, a movable swash plate is disposed in the HST turning pump 72 and linked to the steering handle 9 via a sub-transmission arm (not shown), and the HST turning pump 72 according to the operation amount of the steering handle 9. The discharge amount from is adjusted. The HST turning pump and the HST turning motor are connected by a pipe (not shown), and the output rotation speed of the HST turning motor 73 is controlled in accordance with the discharge amount from the HST turning pump. The output of the HST turning motor 73 and the output from the main / sub transmission 39 are combined in the differential 50, the drive sprockets 90L and 90R are differentially rotated, and the body 1 is turned.

  Specifically, when the steering handle 9 is turned left and right, the discharge amount of the HST turning pump 72 is changed according to the amount of operation of the steering handle 9, and accordingly, the HST motor of the HST turning motor 73 is changed. The output gear 38 is driven to rotate, and the two right and left reverse gears 52L and 52R meshing with the HST motor output gear 38 are rotated in reverse in accordance with the rotation. The reversing gears 52L and 52R are fixed to one ends of the left and right turning drive shafts 43L and 43R, and are fixed to the other ends of the turning drive shafts 43L and 43R via the turning drive shafts 43L and 43R. The differential gears 44L and 44R are driven to rotate, so that the left and right differential gears 44L and 44R are rotated in reverse.

  The differential gears 44L and 44R mesh with the carrier gears 56L and 56R to rotate the left and right carriers 55L and 55R in reverse. The planetary gears 53L and 53R pivotally supported by the left and right carriers 55L and 55R revolve around the sun gears 51L and 51R, but the left and right drive output shafts 59L and 59R are differentially driven by the difference in revolution speed at this time. It is rotated and the body 1 is turned leftward or rightward.

  When the vehicle is traveling straight, the left and right drive sprockets 60L and 60R have the same rotation speed, and the vehicle body 1 is turned when the left and right drive sprockets 60L and 60R have different rotation speeds.

(5) Hydraulic transmission mechanism The small crawler tractor of the present invention is a steering HST turning pump 72 and an HST turning motor for turning the airframe to a drive system behind the forward / reverse switching mechanism 7 for moving the airframe 1 forward and backward. 73 is connected. The HST turning pump 72 and the HST turning motor 73 are connected by a pipe (not shown), and the output rotation of the HST turning motor 73 further depends on the amount of operating oil discharged from the HST turning pump 72. Number and direction of rotation are controlled.

  In the present invention, the HST turning pump 72 is a variable displacement pump. By using the variable displacement pump, the displacement of the HST turning pump can be varied from the steering handle via a link mechanism (not shown) by the turning operation of the steering handle by the driver. Can be varied steplessly. Particularly in the present invention, since the steering hydraulic transmission mechanism for turning the airframe is connected to the drive system behind the forward / reverse switching mechanism for moving the airframe back and forth, the steering handle does not reversely rotate when the vehicle moves backward. Moreover, since a variable displacement pump is used, a pump discharge amount proportional to the power of the drive system can be obtained. At this time, if a constant displacement motor is connected to the variable displacement pump, the vehicle speed and steering are adjusted by adjusting the discharge amount of the variable displacement pump by introducing the combined power of the main shift and the sub shift to the HST turning pump. The turning radius can be made constant by proportionally rotating the motor.

  On the other hand, in the present invention, a variable capacity motor may be used instead of the constant capacity motor. This is because in addition to the change in the discharge amount due to the use of the variable displacement pump, the discharge amount can be further changed by using the variable displacement motor. When the discharge amount by the variable displacement pump is changed, the rotational driving force of the HST motor output gear 38 of the HST turning motor 73 is changed, and the two left and right reverse gears 52L and 52R meshing with the HST motor output gear 38 accompanying the rotation are changed. The rotation is changed, and finally, the rotational driving force of the differential gears 44L and 44R fixed to the other ends of the turning drive shafts 43L and 43R is changed, and the turning radius is changed even when the vehicle speed is the same. Can be made. For example, when the discharge amount is changed in two stages by the variable displacement pump, the steering angle can be controlled to two types of turning speeds, for example, a spin mode and a soft mode even at the same traveling speed. Correspondingly, the turning radius can be changed.

  That is, by reducing the capacity of the HST turning motor relative to the capacity of the HST turning pump, the turning radius of the airframe can be increased, and the HST turning motor capacity can be increased relative to the capacity of the HST turning pump. By making the capacity large, the turning radius of the airframe can be made small.

  Therefore, when performing a pivot turn on a crawler type tractor, it is possible to reduce or increase the pivot turn start steering angle according to the work situation by changing the turning mode. .

  Although the arrangement of the HST turning pump and the HST turning motor is not limited, it is preferable that the HST turning pump 72 is arranged on the side of the transmission 23 and the HST turning motor is arranged on the upper side of the transmission 23. With this arrangement, as shown in FIG. 4, the rotational power after the sub-shift can be input to the HST turning pump input shaft 63 by driving the belt 65 after passing through the plurality of counter shafts 61. . The method for transmitting the rotational power for driving the HST turning pump from the counter shaft is not limited to the belt as described above, and may be a chain or a gear. As described above, transmission from the counter shaft via a belt or the like makes it possible to arrange the position of the HST turning pump at an arbitrary position. By disposing the pump 72 on the side surface of the mission case 23, the ground minimum height of the airframe 1 can be increased.

  The HST turning motor 73 is disposed above the mission case 23, and oil stored in the mission case 23 flows out of the HST turning motor 73 even when the HST turning motor 73 is repaired. In addition, the HST turning motor can be easily removed and maintained, for example, and the working efficiency is improved. Further, when the HST turning motor 73 is disposed on the upper part of the transmission case 23, particularly on the differential mechanism 50, oil leaking from the HST turning motor 73 can be directly flowed down to the differential mechanism.

(6) Others Deceleration is performed via a plurality of brake plates 29 provided at one end of the pinion shaft 22. When a brake pedal (not shown) is operated by a driver's operation, the brake arm 28 is rotated in conjunction with the brake arm 28, and a brake action is generated on the pinion shaft 22 along with the rotation of the brake arm 28 to decelerate the airframe 1. . In particular, the brake plate 29 is located at the right end of the pinion shaft 22, and a brake case (not shown) that houses the brake plate, brake arm, etc. is replaced with a right rear axle case that houses the right planetary gear mechanism. 40R can be integrated. When the HST turning motor 73 is positioned on the left rear axle case, the brake mechanism arranged in the right rear axle case 40R and the HST turning motor arranged in the left rear axle case 40L. The weight with 73 can be harmonized and the weight balance of the airframe 1 can be maintained.

  The work machine is driven through a PTO output shaft. As shown in FIG. 4, a part of the output of the engine 3 is connected from the forward / reverse switching mechanism 7 to the PTO counter shaft 49 via the PTO transmission gear 48 and transmitted to the PTO output shaft 91 at the rear of the machine body. .

  Since the crawler type tractor of the present invention can be manufactured using the basic structure of a small wheel type tractor, many types of tractors can be manufactured at low cost, which is useful.

It is a side view which shows the small crawler type tractor as an example of the small crawler type tractor of this invention. It is a perspective view showing a perspective view of a run part in a small crawler type tractor of the present invention. It is a section top view of the small crawler type tractor of the present invention. It is a section side view of the drive part in the small crawler type tractor of the present invention. It is a figure which shows the differential structure of the small crawler type tractor of this invention. It is a perspective view of the frame structure of the crawler traveling device of the small crawler type tractor of the present invention. It is a perspective view which shows the conventional wheel type tractor. It is a figure explaining ratio of the grounding length (L2) of the said crawler traveling apparatus with respect to the full length (L1) of an upper vehicle body.

Explanation of symbols

  1 Crawler tractor (vehicle), 2 bonnet, 3 engine, 4 cabin, 5 clutch housing, 6 working machine, 7 forward / reverse switching mechanism, 8 driver's seat, 9 steering handle, 20L, 20R input shaft, 21 bevel gear, 22 pinion Shaft, 23 Transmission case, 31 Output shaft, 37 Main shaft, 38 HST motor output gear, 39 Main auxiliary transmission, 40L, 40R Rear axle case, 41 Main transmission shaft, 42 Main transmission gear, 45 Sub transmission shaft, 49 PTO counter Shaft, 50L, 50R Differential mechanism, 58L, 58R Drive output gear, 59L, 59R Axle (axle), 60L, 60R Drive sprocket (sprocket), 61 Counter shaft, 63 Turning HST pump input shaft, 72 Turning HST pump 73 HST motor for turning, 80 Over La running gear, 81L, 81R crawler frame, 84 support member, 85 a driven idler 87 support member, 91 PTO output shaft, 95 crawler belt, 97-wheel tractor.

Claims (3)

A crawler type traveling device having a crawler frame that rotatably supports a driven idler at both ends and a driving sprocket mounted on a rear axle case, and a crawler wound between the driven idler and the driving sprocket. In the small crawler tractor provided at the bottom of the upper car body,
The crawler frame is fixed to the upper vehicle body by at least two support members, and the fixed portion is located behind the vehicle from the tip of the crawler type traveling device. A crawler type traveling device having a crawler frame that rotatably supports a driven idler at both ends and a driving sprocket mounted on a rear axle case, and a crawler wound between the driven idler and the driving sprocket. In the small crawler tractor provided at the bottom of the upper car body,
The crawler frame is fixed to the upper vehicle body by at least two support members,
A small crawler tractor in which a ground contact length (L2) of the crawler traveling device with respect to a total length (L1) of the upper vehicle body is 0.5 or more.   The small crawler tractor according to claim 1 or 2, wherein the crawler frame is fixed by the upper vehicle body and a bolt.

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