JP2016217453A - Lubricating oil supply structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lubricating oil supply structure that can constantly supply a sufficient amount of lubricating oil to bearings for axles that require high support strength.SOLUTION: A case that houses axles and tapered roller bearings that support the axles is provided with lubricating oil ports for supplying oil discharged from a hydraulic pump as lubricating oil to the bearings. Oil pipes that supply the oil discharged from the hydraulic pump is provided outside the case, and the oil pipes are connected to the lubricating oil ports. Speed reduction mechanisms that consist of planetary gear mechanisms and use the axles as output shafts are housed in the case. Oil reservoirs that communicate with the lubricating oil ports are provided in proximity to the bearings in the case.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a structure for supplying lubricating oil to a bearing that supports an axle applied to a vehicle such as a tractor.

  Conventionally, for example, as shown in Patent Document 1, a tractor having a structure in which a planetary gear mechanism is provided as a reduction gear mechanism between left and right differential output shafts, which are output shafts of a differential mechanism, and left and right axles. Is known. The planetary gear mechanism is considered to be advantageous as a reduction gear mechanism for large and relatively large tractors in that a large reduction ratio can be secured. Here, the planetary gear mechanism shown in Patent Document 1 is arranged near the differential mechanism of the tractor, and has a configuration in which the differential output shaft on the input side is short and the axle on the output side is long. In this case, in the axle having a long shaft length, the inner end portion near the differential mechanism and the outer end portion near the hub at the outer end are supported by bearings in a form like a double-end support. .

  Further, as shown in Patent Document 2, a tractor having a lubricating oil line that supplies oil discharged from a lubricating oil pump driven by a prime mover to various hydraulic devices such as a hydraulic clutch and a hydraulic cylinder is known. Yes. However, axle bearings have not been incorporated in the lubricating oil line that receives the oil discharged from the lubricating oil pump as described above, and the lubricating oil is compensated from the oil reservoir in the transmission case or axle case. Or, as shown in Patent Document 3, the structure is such that the axle is supported by a ball bearing filled with grease, and lubricating oil is not supplemented by oil discharged from the lubricating oil pump. This is due to the timely grease replenishment by the operator.

JP 2000-81057 A JP 2008-202721 A JP 2013-86715 A

  Here, while ensuring the reduction ratio, considering the cost reduction and the appropriate layout, the planetary gear mechanism is located closer to the hub for mounting on the wheel formed on the outer end of the axle, that is, the tractor. Considering shortening the axle by arranging it closer to the left and right outside, the bearings of such a short axle supported by the planetary gear mechanism should have a plurality of bearings in the axial direction (left and right direction) of the axle. Even if it is provided, since the ratio of the protruding portion of the axle from the axle case to the hub is increased, it is shaped like a cantilever and a large stress is applied to the axle. In order to withstand this, it is considered that a ball bearing is weak and a strong structure such as a tapered roller bearing is required.

  However, a bearing such as a tapered roller bearing requires a lot of lubricating oil, and the portion closer to the left and right outer sides of the tractor moves up and down as the tractor tilts left and right. When the part that has been moved moves upward, the lubricating oil is easily removed. On the other hand, the axle bearing is not incorporated in the lubricating oil line that can positively receive the oil discharged from the hydraulic pump as described above. Even if it is a grease filling type, the grease compensation depends on the operator's judgment, so if the judgment of the timing is wrong or accidentally forgotten, unexpected bearing damage will occur there is a possibility.

  An object of the present invention is to provide a lubricating oil supply structure capable of always supplying sufficient lubricating oil without any breaks to the axle bearings arranged and supported in this manner.

  In order to achieve the above object, a lubricating oil supply structure according to the present invention supplies oil discharged from a hydraulic pump as lubricating oil to a bearing to a housing that houses an axle and a bearing that supports the axle. The lubricating oil port is provided.

  An oil pipe for supplying oil discharged from the hydraulic pump is provided outside the casing, and the oil pipe is connected to the lubricating oil port.

  The bearing is a tapered roller bearing.

  Further, a deceleration mechanism having the axle as an output shaft is accommodated in the housing.

  The reduction mechanism is a planetary gear mechanism.

  Also, a lubricating oil reservoir that communicates with the lubricating oil port is provided in the housing in the vicinity of the bearing.

  A plurality of the bearings are provided, and a gap between the plurality of bearings is used as the lubricating oil reservoir.

  In the lubricating oil supply structure according to the present invention, a lubricating oil port for supplying discharged oil from the hydraulic pump as lubricating oil to the bearing is provided in a housing that houses the axle and the bearing that supports the axle. By so doing, as long as the hydraulic pump is driven, the oil discharged from the hydraulic pump is always supplied to the bearings without a break, and there is no shortage of lubricating oil. Therefore, even if the axle is short and the bearings are arranged on the left and right outer portions of the vehicle such as a tractor and are arranged in a portion where the vehicle is frequently moved up and down due to the left and right inclination of the vehicle, It does not cause problems due to lack of lubricating oil.

  Further, an oil pipe for supplying the discharge oil of the hydraulic pump is provided outside the casing, and the oil pipe is connected to the lubricating oil port, thereby forming an oil passage to the bearing in the casing. Lubricating oil can be supplied with a low-cost piping structure to bearings arranged at locations far from the hydraulic pump such as tractors and the like near the left and right outer sides of the vehicle. .

  Further, by using a tapered roller bearing as the bearing, the axle can be reliably supported by the tapered roller bearing even when the axle has a short structure and the bearing is strongly stressed. Even in a tapered roller bearing that requires a large amount of lubricating oil, a sufficient amount of lubricating oil is always supplied to the tapered roller bearing by the structure as described above.

  In addition, in the case where the speed reduction mechanism having the axle as the output shaft is accommodated in the housing, the speed reduction mechanism is brought close to the hub at the outer end of the axle and the axle is shortened, as described above, It is possible to prevent the shortage of lubricating oil. Furthermore, oil from the lubricating oil port can be supplied through the housing as lubricating oil to the speed reduction mechanism.

  Further, by adopting a planetary gear mechanism as the reduction mechanism, the planetary gear mechanism can be used when the vehicle to be applied needs to ensure a large axle support strength or a reduction ratio in the reduction mechanism, such as a large tractor. The configured speed reduction mechanism ensures such axle support strength and speed reduction ratio.

  Also, a lubricating oil reservoir that communicates with the lubricating oil port is provided in the housing in the vicinity of the bearing. As a result, even if the part where the bearing is arranged is a part where the vertical movement is frequent as described above, the lubricating oil reservoir is constantly filled with the oil discharged from the hydraulic pump and is brought close to it. Sufficient lubricating oil can be constantly supplied to the bearing.

  Further, by providing a plurality of the bearings and making the gap between the plurality of bearings the lubricating oil reservoir, one gap between the bearings becomes the adjacent lubricating oil reservoir for the bearings on both sides thereof, and the bearing Even if the number is increased, the number of lubricating oil reservoirs can be kept small, contributing to cost reduction by downsizing the casing and axle and reducing the number of machining points.

It is a side view of tractor 100 provided with transmission 1 concerning the example of the present invention. 2 is a skeleton diagram showing a power system of the tractor 100. FIG. 2 is a hydraulic circuit diagram for driving a hydraulic device in the tractor 100. FIG. 2 is a rear perspective view of the transmission 1. FIG. 1 is a front perspective view of a transmission 1. FIG. 1 is a side view of a transmission 1. FIG. 1 is a plan view of a transmission 1. FIG. 2 is a rear view of the transmission 1. FIG. It is a plane sectional view of transmission 1 by AA arrow in FIG. It is a plane sectional view of transmission 1 by a BB arrow in FIG. It is a rear surface sectional view of transmission 1 by CC arrow in Drawing 6. FIG. 7 is a partial rear cross-sectional view of the transmission 1 as viewed in the direction of arrows DD in FIG. 6.

  As an example of a vehicle to which the present invention is applied, an overall structure of a tractor 100 shown in FIGS. 1 and 2 will be described. 1 and 2, an arrow F indicates the front of the tractor 100, and an arrow F in FIGS. 4 to 7, 9, and 10 described later indicates that the transmission 1 described later is mounted on the tractor 100. The front of the tractor 100 and the transmission 1 is shown. Regarding the position and direction of each member or part mentioned in the following description of the tractor 100 and the transmission 1, it is assumed that the arrow F is directed forward.

  As shown in FIG. 1, the tractor 100 includes a vehicle body frame 101. A front axle drive case 20 is supported at the front portion of the body frame 101, and a pair of left and right front wheels 9 are supported by the front axle drive case 20. A bonnet 102 is mounted above the front portion of the vehicle body frame 101, and the engine 10 shown in FIG. As shown in FIG. 1, a cabin 103 is mounted behind the hood 102 and above the rear part of the vehicle body frame 101. From the rear end of the body frame 101, a top link 115a and a pair of left and right lower links 115b are extended rearward, and a link mechanism 115 for attaching a work implement of a three-point link type is provided by these links 115a and 115b. It is composed.

  As shown in FIG. 1, the transmission 1 is supported on the rear portion of the vehicle body frame 101 below the cabin 103. The transmission 1 supports the axles 28 (the left axle 28L and the right axle 28R; see FIG. 4 and the like) of the pair of left and right rear wheels 8, and outputs front wheel drive power to the front axle drive case 20. A drive shaft 34 (see FIG. 2) is supported. The transmission 1 supports a rear PTO shaft 60 (see FIG. 2, FIG. 4 and the like) at the rear. A work machine such as a rotary cultivator mounted on the tractor 100 is driven by the rear PTO shaft 60 via the link mechanism 115.

  As shown in FIG. 1, a seat 105 is disposed in a cab constituted by a cabin 103, and a steering handle 107 is extended from an upper portion of a front column 106 that stands in front of the cabin. A forward / reverse switching (reverser) lever 108 is disposed in the vicinity of. In the vicinity of the left and right sides of the seat 105, a work machine up / down operation switch, a PTO clutch switch, and the like are provided in addition to the main transmission lever 109, the auxiliary transmission lever 110, the PTO transmission / reverse lever 111. A clutch pedal 112 extends downward from the front column 106, and an accelerator pedal 113, a pair of left and right brake pedals (not shown), and the like are provided on the floor surface that serves as a foot of the front column 106. A differential lock pedal 114 is provided near the seat 105 on the floor. In addition, operation tools such as switches for setting the two-wheel / four-wheel drive mode, front wheel acceleration, etc., and various instruments are also arranged at the top of the front column 106 provided at the front of the cab. Has been.

  The power system of the tractor 100 will be described with reference to FIG. In the tractor 100, as a power system for transmitting the output of the engine 10, a traveling power system PT 1 for transmitting power to the rear wheels 8 and the front wheels 9 and a power system for driving a work machine for transmitting power to the rear PTO shaft 60. PT2 is provided. The transmission 1 has a longitudinally extending input shaft 21 shared by both power systems PT1 and PT2. The input shaft 21 is connected to the output shaft of the engine 10 via the transmission shaft 11 with a universal joint.

  The traveling power system PT1 has a main transmission 12, a reverser clutch 13, and a subtransmission 14 as a common drive system PT1m that transmits power distributed to the front wheels 8 and the rear wheels 9, and is driven by the engine 10. The rotational power of the input shaft 21 is transmitted from the main transmission 12 to the sub transmission 14 via the reverser clutch 13. Further, the traveling power system PT1 is configured as a rear wheel drive system PT1r that distributes the output of the auxiliary transmission 14 of the common drive system PT1m to the axles 28 of the left and right rear wheels 8, as a rear differential mechanism 15, a differential lock mechanism 16, and a pair of left and right mechanisms. A front wheel drive gear mechanism is provided as a front wheel drive system PT1f that includes a brake 17, a first reduction gear mechanism 18, a second reduction gear mechanism 19, and the like, and distributes the output of the auxiliary transmission device 14 to the axle 9a of the left and right front wheels 9. 30, a front wheel drive mode setting clutch 32, a front wheel drive shaft 34, a front differential mechanism 36, a final reduction gear mechanism 37, and the like.

  Of the driving power system PT1, the common drive system PT1m including the main transmission 12, the reverser clutch 13, and the auxiliary transmission 14, all the components of the rear wheel drive system PT1r from the rear differential mechanism 15 to the axle 28, and the front wheel drive The components from the front wheel drive gear mechanism 30 to the front wheel drive shaft 34 in the system PT1f are incorporated in the transmission 1. In the front wheel drive system PT1f, the front differential mechanism 36 is accommodated in the front axle drive case 20, and its input shaft 36a projects rearward from the front axle drive case 20, and is connected to the transmission 1 via the transmission shaft 35. The front wheel drive shaft 34 is supported. A final reduction gear mechanism 37 is interposed between the front axle drive case 20 and the axles 9 a of the left and right front wheels 9, and the output of the front differential mechanism 36 passes through the left and right final reduction gear mechanisms 37 to the left and right. It is assumed that it is transmitted to the front wheel 9.

  The structure of each component of the traveling power system PT1 in the transmission 1 will be described in detail with reference to FIG. First, in the common drive system PT1m, in this embodiment, a hydraulic mechanical continuously variable transmission (hereinafter referred to as “HMT”) is the main transmission 12. The HMT as the main transmission 12 includes an axial piston type hydraulic pump 12P and an axial piston type hydraulic motor 12M that is driven by the supply of hydraulic oil from the hydraulic pump 12M. The HMT has a pump shaft 12a that is disposed on the same axis as the input shaft 21 and is connected to the input shaft 21 so as to be rotatable integrally with the input shaft 21. The hydraulic pump 12P and the hydraulic motor 12M is arranged on the same axis on the pump shaft 12a. The HMT is provided with a pump swash plate 12b that is a movable swash plate that sets the volume of the hydraulic pump 12P and a motor swash plate 12c that is a fixed swash plate that defines the volume of the hydraulic motor 12M. Yes. The output shaft 22 of the main transmission 12 is a cylindrical member that extends in the front-rear direction on the same axis as the input shaft 21, and is arranged around the input shaft 21 so as to be rotatable relative to the input shaft 21. It is installed. The motor swash plate 12 c is disposed on the same axis as the output shaft 22 and is connected to the output shaft 22 so as to rotate integrally with the output shaft 22.

  The pump swash plate 12b can be tilted in the deceleration tilt direction from the position of the tilt angle 0 (a state where the pump swash plate 12a and the input shaft 21 are arranged perpendicularly), and from the position of the tilt angle 0. The tilting direction for speed increase can be tilted in the direction opposite to the tilting direction for deceleration. The motor swash plate 12c and the output shaft 22 rotate in the same direction as the rotation of the input shaft 21 and the pump shaft 12a regardless of the tilt angle and direction of the pump swash plate 12b. When 0, it rotates at the same speed as the input shaft 21 and the pump shaft 12a. As the pump swash plate 12b is tilted in the deceleration tilt direction from the tilt angle 0 position, the rotational speed of the motor swash plate 12c and the output shaft 22 decreases, and when the maximum tilt angle is reached in the deceleration tilt direction, the motor swash plate The rotational speeds of 12c and the output shaft 22 are zero. On the other hand, as the pump swash plate 12b is tilted from the position of the tilt angle 0 in the speed-increasing tilt direction, the rotational speed of the motor swash plate 12c and the output shaft 22 increases, and reaches the maximum tilt angle in the speed-increasing tilt direction. The rotational speeds of the motor swash plate 12c and the output shaft 22 are maximum (for example, twice the rotational speeds of the input shaft 21 and the pump shaft 12a).

  The tilt angle and direction of the pump swash plate 12 b are changed by operating the main transmission lever 109. The main transmission lever 109 can be tilted from the speed 0 position to the maximum speed position. When the main transmission lever 109 is at the speed 0 position, the pump swash plate 12b is tilted to the maximum tilt angle position in the deceleration tilt direction, so that the motor swash plate 12c and the output shaft 22 are not affected by the rotation of the engine 10. The rotation speed is zero. As the main shift lever 109 is tilted from the speed 0 position to the maximum speed position, the pump swash plate 12b decreases the tilt angle from the maximum tilt angle position to the tilt angle 0 position in the deceleration tilt direction, and eventually tilts. When the main transmission lever 109 reaches the maximum speed position by tilting from the position of the angle 0 in the speed-increasing tilt direction to increase the tilt angle, the maximum tilt angle position in the speed-increasing tilt direction is reached.

  The tilt angle and direction of the pump swash plate 12b are also controlled by depressing the accelerator pedal 113. That is, as the amount of depression of the accelerator pedal 113 is increased, the engine speed increases, and the pump swash plate 12b increases from the maximum tilt angle position in the deceleration tilt direction in accordance with the increase in the engine speed. And the speed ratio of the HMT as the main transmission 12, that is, the rotational speed ratio of the output shaft 22 to the input shaft 21 is automatically adjusted so as to correspond to the engine speed. .

  The transmission 1 is provided with a reverser clutch shaft 23, an idle shaft 24, and an auxiliary transmission output shaft 25 extending in the front-rear direction, which are parallel to the input shaft 21 and the output shaft 22 of the main transmission 12. Flat gears 22a and 22b are fixed to the output shaft 22, and the reverser clutch shaft 23 is provided with a reverser clutch 13 having a structure in which a forward clutch 13F and a reverse clutch 13R are integrally combined. Flat gears 13 a and 13 b are attached to the reverser clutch shaft 23 via the reverser clutch 13. The spur gear 13a meshes directly with the spur gear 22a, and the spur gears 22a and 13a constitute a forward gear train. The spur gear 13b meshes with the spur gear 22b via an idle gear 24a supported on the idle shaft 24, and the spur gears 22b, 24a, and 13b constitute a reverse gear train.

  The reverser clutch 13 is operated by operating the reverser lever 108 so that the forward clutch 13F is engaged and the reverse clutch 13R is separated, the forward clutch 13F is separated and the reverse clutch 13R is engaged, and the forward clutch 13F / reverse is operated. The clutch 13R is set to one of three neutral states in which both are separated. When the reverser clutch 13 is set to the forward state, the rotational power of the output shaft 22 of the main transmission 12 is transmitted to the reverser clutch shaft 23 via the forward gear train composed of the spur gears 22a and 13a. 23 rotates in the forward direction. When the reverser clutch 13 is set in the reverse drive state, the rotational power of the output shaft 22 of the main transmission 12 is transmitted to the reverser clutch shaft 23 via the reverse gear train including the spur gears 22b, 24a, and 13b. The clutch shaft 23 rotates in the reverse direction. When the reverser clutch 13 is set to the neutral state, the reverser clutch shaft 23 is not driven regardless of the rotation of the output shaft 22 of the main transmission 12.

  Between the reverser clutch shaft 23 and the sub-transmission output shaft 25, a low-speed gear train, a medium-speed gear train, and a high-speed gear train constituting a gear type stepped transmission as the sub transmission 14 are provided. That is, flat gears 23a, 23b, and 23c are fixed to the reverser clutch shaft 23, and flat gears 25a, 25b, and 25c are attached to the auxiliary transmission output shaft 25 so as to be relatively rotatable. The low speed gear train is configured by direct meshing, the medium gear train is configured by direct meshing of the spur gears 23b and 25b, and the high speed gear train is configured by direct meshing of the spur gears 23c and 25c. On the auxiliary transmission output shaft 25, the clutch slider 14a is slidable along the auxiliary transmission output shaft 25 between the flat gears 25a and 25b, and in the vicinity of the flat gear 25c. The auxiliary transmission output shaft 25 is provided so as not to rotate relative to the auxiliary transmission output shaft 25 (integral rotation is possible). The clutch sliders 14a and 14b are slid by the operation of the auxiliary transmission lever 110, and any one of the flat gears 25a, 25b, and 25c is engaged with the auxiliary transmission output shaft 25 through the clutch sliders 14a or 14b. To do.

  That is, the sub-transmission device 14 meshes the clutch slider 14a with the flat gear 25a, and transmits the power from the reverser clutch shaft 23 to the sub-transmission output shaft 25 via the low-speed gear train composed of the flat gears 23a and 25a. A middle speed stage state in which the clutch slider 14a is engaged with the flat gear 25b and power is transmitted from the reverser clutch shaft 23 to the auxiliary transmission output shaft 25 via a medium speed gear train comprising the flat gears 23b and 25b. And the high speed stage state in which the clutch slider 14b is meshed with the flat gear 25c and the power is transmitted from the reverser clutch shaft 23 to the auxiliary transmission output shaft 25 via the high speed gear train including the flat gears 23c and 25c. One of the speed stages is set. Since the rotation direction of the reverser clutch shaft 23 is set to the forward direction or the reverse direction by switching the reverser clutch 13, the continuously variable transmission of the main transmission 12 and the high, medium and low three-stage transmission of the auxiliary transmission 14 are performed. A wide and fine speed change effect can be obtained at both forward and reverse settings. It is possible to set the auxiliary transmission 14 in a neutral state in which all the spur gears 25a, 25b, and 25c are not engaged with the clutch sliders 14a and 14b.

  A bevel pinion 25 d is fixed (or formed) at the rear end of the auxiliary transmission output shaft 25, and the bevel pinion 25 d meshes with a bevel ring gear 15 a that is an input gear of the rear differential mechanism 15. On the other hand, a spur gear 25e is fixed to the front end portion of the auxiliary transmission output shaft 25. The spur gear 25e and a spur gear 31a fixed to the counter shaft 31 constituting the front wheel drive gear mechanism 30 are provided. Direct meshing. Thus, the rotational power of the auxiliary transmission output shaft 25 is distributed to the rear differential mechanism 15 of the rear wheel drive system PT1r and the forward drive gear mechanism 30 of the front wheel drive system PT1f. Note that the member 25f shown in FIG. 2 as related to the spur gear 25e is a rotation speed detection member, and will be described later based on the rotation speed of the speed change output shaft 25 detected by the rotation speed detection member 25f. It is assumed that on / off control of the front wheel acceleration clutch 32H is performed.

  The rear differential mechanism 15 of the rear wheel drive system PT1r includes the bevel ring gear 15a, a differential case 15b fixed to the left and right sides of the bevel ring gear 15a, a bevel differential pinion 15c and a bevel differential pinion 15c disposed in the differential case 15b. Is provided with a differential pinion shaft 15d that pivotally supports the differential case 15b. The bevel ring gear 15a is one of a pair of left and right differential output shafts 26 (left differential output shaft 26L and right differential output shaft 26R) disposed on the same axis in the left-right direction (this embodiment). The differential case 15b is mounted on the right differential output shaft 26R so as to be rotatable relative to the right differential output shaft 26R), and the differential case 15b has a boss portion 15b1 formed at the left and right ends opposite to the bevel ring gear 15a. 26 (26L, 26R) is mounted on the other (left differential output shaft 26L in this embodiment) so as to be relatively rotatable. The inner ends of the differential output shafts 26 (26L and 26R) are disposed in the differential case 15b, and the bevel differential side gears 26a and 26b are fixed to the inner ends of the differential output shafts 26L and 26R. ing. Each bevel differential pinion 15c meshes with the bevel differential side gears 26a and 26b of the left and right differential output shafts 26L and 26R. Of the pair of bevel differential side gears 26a and 26b, the bevel differential side gear 26a of the differential output shaft 26L to which the boss portion 15b1 of the differential case 15b is attached has a hole for inserting a differential lock pin 16b described later. ing.

  The rear differential mechanism 15 is provided with a differential lock mechanism 16. The differential lock mechanism 16 includes a slide ring 16a that is slidably mounted on the boss portion 15b1 of the differential case 15b in the axial direction, and a differential lock pin 16b that extends in the left-right direction and is fixed to the slide ring 16a. Yes. A hole is provided in the main body portion of the differential case 15b, and the tip of the differential lock pin 16b inserted through the hole is disposed in the main body portion of the differential case 15b. The slide ring 16a is set to either a lock release position away from the main body portion of the differential case 15b or a differential lock position close to the main body portion of the differential case 15b by the sliding. When the slide ring 16a is arranged at the differential lock position, the tip of the differential lock pin 16b extending from the slide ring 16a is connected to the bevel differential side gear 26 through the hole of the bevel differential side gear 26a of the differential output shaft 26L to which the differential case 15b is attached. The differential case 15b is locked to the differential output shaft 26L, and thereby the left and right differential output shafts 26L and 26R are differentially locked (in a state in which the differential cannot be performed). When the slide ring 16a is set to the unlocking position, the tip of the differential lock pin 16b is retracted from the bevel differential side gear 26a, so that the differential output shafts 26L and 26R are in a differential state.

  Although not shown in FIG. 2, as can be seen in FIG. 11, a left and right extended fork shaft 40 extends in the transmission case 2 described later of the transmission 1 and extends from the fork shaft 40. The provided fork 40a is engaged with the annular groove of the slide ring 16a. The fork shaft 40 is slidable in the axial direction (left-right direction), and the slide ring 16a is slid through the fork 40a by the sliding, and is arranged in the differential lock position or the unlock position. The The fork shaft 40 and the fork 40a are urged by a spring 40b wound around the fork shaft 40 in a direction in which the slide ring 16a is disposed at the unlocked position. The fork shaft 40 is slid by the operation of the differential lock pedal 114. When the differential lock pedal 114 is not depressed, the slide ring 16a is in the unlocked position, and when the differential lock pedal 114 is depressed, the slide ring 16a is disposed at the differential lock position.

  2, from left and right differential output shafts 26 (left differential output shaft 26L and right differential output shaft 26R) to left and right axles 28 (left axle 28L and right axle 28R) in the rear wheel drive system PT1r. The configuration of this part will be described. Hereinafter, in the description of the structure of the rear wheel drive system PT1r, in the axial direction (left and right direction) of each differential output shaft 26, the rear differential mechanism 15 side is “inside”, and the opposite side to the rear differential mechanism 15, that is, the axle 28 side. Is referred to as "outside". FIG. 2 shows a portion of the rear wheel drive system PT1r from the rear differential mechanism 15 to the left axle 28 (28L). The outer portion of the right differential output shaft 26R, the right deceleration shaft 27, the right The right first reduction gear mechanism 18 interposed between the outer portion of the differential output shaft 26R and the right reduction shaft 27, the right second reduction gear mechanism 19 and the right axle 28 (28R) are provided. The illustration is omitted.

  Brakes 17 (left brake 17L and right brake 17R (see FIGS. 9, 10, and 11)) are provided on the inner side of each differential output shaft 26. The left and right brakes 17L and 17R are operated separately by stepping on a pair of left and right brake pedals (not shown) provided in the cabin 103 as described above. Note that the left and right brakes 17L and 17R can be operated by automatic brake hydraulic cylinders (hydraulic actuators) 72L and 72R shown in FIG. . This is because when an operation tool such as a switch for automatic brake setting (not shown) provided in the cabin 103 is set to automatic brake, when the steering handle 107 is rotated for turning the vehicle, the brake 17 on the inner side of the turn is set. The hydraulic cylinder 76L or 76R is operated, the brake 17 is applied, the rear wheel 8 inside the turning is braked, and the tractor 100 can be turned slightly. In addition to the automatic brake system that brakes the rear wheel 8 on the inside of the turn as described above, the structure of the tractor 100 for small turns is higher than that of the rear wheel 8 when turning, as will be described later. A front wheel speed increasing system is also provided.

  A flat gear 18 a is fixed (or formed) at the outer end of each differential output shaft 26. A pair of left and right deceleration shafts 27 extending in the left-right direction are arranged in parallel to the outer portions of the pair of left and right differential output shafts 26L and 26R. Each reduction shaft 27 is a gear shaft in which a flat gear 18b having a diameter larger than that of the flat gear 18a is fixed (or formed) on the outer periphery thereof. The flat gear 18b is directly meshed with the flat gear 18a of each differential output shaft 26, and is interposed between each differential output shaft 26 and each reduction shaft 27 by the flat gears 18a and 18b. A first reduction gear mechanism 18 is configured.

  The left and right axles 28 (28L and 28R) are arranged outside the left and right deceleration shafts 27 on the same axis as the deceleration shaft 27. The second axles 28 and 28R are disposed between the deceleration shaft 27 and the axles 28. A reduction gear mechanism 19 is interposed. The first reduction gear mechanism 18 meshes small and large diameter flat gears 18a and 18b, whereas the second reduction gear mechanism 19 includes a sun gear 19a, an internal gear 19b, a planetary gear 19c, and a carrier 19d. It has a planetary gear mechanism. The reduction shaft 27 is also a sun gear shaft of a planetary gear mechanism that is the second reduction gear mechanism 19, and a sun gear 19 a is fixed (or formed) thereto. Around the sun gear 19a, an internal gear 19b fixed to the inner peripheral surface of a post-transmission housing of the transmission 1 is disposed, and a planetary gear 19c is interposed between the sun gear 19a and the internal gear 19b. . The planetary gear 19c is pivotally supported by a carrier 19d, and the carrier 19d is fixed to the inner end of the axle 28. Each planetary gear 19c meshed with the sun gear 19a and the internal gear 19b revolves around the sun gear 19a as the sun gear 19a rotates, and the carrier 19d and the axle 28 rotate due to the revolution of the planetary gear 19c.

  As described above, the rear wheel drive system PT1r in the traveling power system PT1 receives the rotational power of the auxiliary transmission output shaft 25 by the rear differential mechanism 15, and distributes the rotational power to the left and right differential output shafts 26L and 26R. Thus, the rotational power of each differential output shaft 26 is transmitted to the left and right axles 28 via the reduction shaft 27 and the two reduction gear mechanisms 18 and 19, and the rear wheels of such a configuration are used. The drive system PT1r is all incorporated in the transmission 1 as described above.

  In the front wheel drive system PT1f, the structure from the front wheel drive shaft 34 to the axle 9a of the left and right front wheels 9 via the front differential mechanism 36 is as described above. Here, in the front wheel drive system PT1f, the transmission 1 will be described. The spur gears 25e and 31a constitute a reduction gear train that transmits the rotational power of the auxiliary transmission output shaft 25 to the counter shaft 31. Flat gears 31b and 31c are fixed to the counter shaft 31, and a front wheel normal speed driving clutch 32L and a front wheel acceleration driving clutch 32H are provided on a front wheel driving clutch shaft 33 disposed in parallel to the counter shaft 31. A drive mode switching clutch 32 having a combined structure is provided. Spur gears 32 a and 32 b are attached to the front wheel drive clutch shaft 33 via the drive mode switching clutch 32. The spur gear 32a meshes directly with the spur gear 31b, and the spur gears 31b and 32a constitute a front wheel normal speed drive gear train. The spur gear 32b is directly meshed with the spur gear 31c, and the spur gears 31c and 32b constitute a front wheel speed increasing drive gear train. The front wheel speed increasing gear train has a smaller output / input gear diameter ratio than the front wheel normal speed driving gear train.

  The drive mode switching clutch 32 is operated by operating the steering wheel 107 by operating the steering mode 107 (hereinafter referred to as “driving mode operating tool”), which is not shown in the drawing. Both the normal four-wheel drive state in which the front wheel acceleration drive clutch 32H is joined and separated, the front wheel acceleration drive state in which the front wheel normal speed drive clutch 32L is separated and the front wheel acceleration drive clutch 32H is joined, and both the clutches 32L and 32H are both One of the two-wheel drive states that are separated from each other is set. On the other hand, regarding the state of power transmission to the front wheels 9, one of a two-wheel drive mode, a normal four-wheel drive mode, and a front wheel acceleration mode is set by operating the drive mode operation tool.

  When the normal four-wheel drive mode is set, the drive mode switching clutch 32 is set to the normal four-wheel drive state regardless of the operation of the steering handle 107, and the rotational power of the counter shaft 31 is constituted by the spur gears 31b and 32a. The transmission is transmitted to the front wheel drive clutch shaft 33 via the forward normal speed drive gear train, and the front wheel drive clutch shaft 33 rotates at a normal speed. Thereby, the front wheel 9 is rotationally driven at a speed substantially synchronized with the rear wheel 8.

  When the steering wheel 107 is rotated for turning the vehicle in the state where the front wheel acceleration mode is set, the drive mode switching clutch 32 is switched to the front wheel acceleration driving state. At this time, the rotational power of the counter shaft 31 is transmitted to the front wheel drive clutch shaft 33 via the front wheel speed increase drive gear train comprising the spur gears 31c and 32b, and the rotation of the front wheel drive clutch shaft 33 is increased. The Thereby, the rotational speed of the front wheel 8 becomes higher than that of the rear wheel 7, and the tractor 100 can be turned slightly without making the field rough. On the other hand, even when the front wheel acceleration mode is set, as long as the steering handle 107 is placed in the straight traveling position, the drive mode switching clutch 32 is normally set to the four-wheel drive state, and the front wheel 9 is substantially synchronized with the rear wheel 8. To rotate.

  When the two-wheel drive mode is set, the drive mode switching clutch 32 is set to the two-wheel drive state, and the front-wheel drive clutch shaft 33 is not driven regardless of the rotation of the counter shaft 31. Even in the two-wheel drive mode, it may be considered that the front-wheel normal-speed drive clutch 32L is in a half-clutch state so that some power is transmitted to the front-wheel drive clutch shaft 33.

  A flat gear 33 a is fixed (or formed) to the front wheel drive clutch shaft 33, and directly meshed with a flat gear 34 a fixed (or formed) to the front wheel drive shaft 34. These flat gears 33a and 34a constitute a gear train for transmitting power from the front wheel drive clutch shaft 33 to the front wheel drive shaft 34.

  This completes the description of the structure of the traveling power system PT1 shown in FIG. Next, the structure of the PTO drive power system PT2 shown in FIG. 2 will be described. Gears 51 a and 51 b are fixed to a cylindrical PTO drive shaft 50. The gear 51 a meshes with a gear 21 a fixed to the input shaft 21, and the gear 51 b meshes with a gear 51 c fixed to the pump drive shaft 52. Thus, the rotational power of the input shaft 21 is transmitted to the pump drive shaft 52 via the pump drive gear train 51 including the gears 21a, 51a, 51b, and 51c. A tandem hydraulic pump set 62 is connected to the pump drive shaft 52. In this way, as long as the power of the engine 10 is transmitted to the input shaft 21 of the transmission 1, the first and second hydraulic pumps 62 a and 62 b described later are driven by the power of the engine 10. ing.

  The cylindrical PTO drive shaft 50 is rotatably provided around the PTO clutch shaft 54, and a hydraulic PTO clutch 53 is interposed between the PTO drive shaft 50 and the PTO clutch shaft 54. Yes. Regardless of whether the PTO clutch 53 is turned on or off, the rotational power of the input shaft 21 is transmitted to the pump drive shaft 52 via a pump drive gear train 51 (gears 21a, 51a, 51b, 51c). The rotational power of the input shaft 21 transmitted to the PTO drive shaft 50 via 21a and 51a is transmitted to the PTO clutch shaft 54 only when the PTO clutch 53 is engaged.

  The rotational power of the input shaft 21 transmitted to the PTO clutch shaft 54 via the PTO clutch 53 is transmitted to the rear PTO shaft 60 via the PTO transmission / reverse gear mechanism 55, the PTO transmission shaft 59, and the gears 59a and 60a. Is done. The PTO speed change / reverse gear mechanism 55 includes a PTO speed change drive shaft 56 connected to the PTO clutch shaft 54 so as to be integrally rotatable on the same axis, a PTO speed change drive shaft 57 parallel to the PTO speed change drive shaft 56, and The idle shaft 58 includes a plurality of PTO transmission gear trains and PTO reverse gear trains interposed between the PTO transmission drive shaft 56 and the PTO transmission driven shaft 57.

  That is, in the PTO speed change / reverse gear mechanism 55, the PTO speed change drive shaft 56 is fixed (or formed) with a low speed drive gear 56a, a medium speed drive gear 56b, a high speed drive gear 56c, and a reverse drive gear 56d which are flat gears. On the PTO speed change driven shaft 57, a low speed driven gear 57a, a medium speed driven gear 57b, a high speed driven gear 57c, and a reverse driven gear 57d, which are flat gears, are mounted so as to be relatively rotatable. The low-speed drive gear 56a and the low-speed driven gear 57a are directly meshed to form a PTO low-speed gear train, and the medium-speed drive gear 56b and the medium-speed driven gear 57b are directly meshed to form a PTO medium-speed gear train. The high-speed driving gear 56c and the high-speed driven gear 57c are directly meshed to form a PTO high-speed gear train, and these three gear trains are used for the PTO transmission / reverse gear mechanism 55 in the forward 3-speed PTO. A transmission gear train is configured. On the other hand, the reverse drive gear 56d and the reverse driven gear 57d are meshed with each other via an idle gear 58a on the idle shaft 58, and the PTO reverse gear in the PTO speed change / reverse gear mechanism 55 is engaged by these gears 56d, 58a and 57d. Constitutes a column.

  Further, the PTO speed change / reverse gear mechanism 55 is connected to the PTO speed change driven shaft 55 by driving a gear train selected from the PTO low speed gear train, the PTO medium speed gear train, the PTO high speed gear train, and the PTO reverse gear train. Clutch sliders 55a, 55b, and 55c. That is, the clutch slider 55a is located between the low-speed / medium-speed driven gears 57a and 57b, the clutch slider 55b in the vicinity of the high-speed driven gear 57c, and the clutch slider 55c in the vicinity of the reverse driven gear 57d are relatively non-rotatable. The PTO speed change driven shaft 57 is slidably mounted in the center direction. When any one of the clutch sliders 55a, 55b, and 55c meshes with one of the driven gears 57a, 57b, 57c, and 57d, the rotational power of the PTO speed change drive shaft 56 via the corresponding gear train. Is transmitted to the PTO speed change driven shaft 57.

  The PTO transmission driven shaft 57 is connected to a PTO transmission shaft 59 on the same axis so as to be rotatable integrally with the PTO transmission driven shaft 57. The rear PTO shaft 60 extends in parallel to the PTO transmission shaft 59, and a gear 58a fixed to the PTO transmission shaft 58 and a gear 60a fixed to the rear PTO shaft 60 mesh with each other to engage the PTO transmission shaft. A gear train for transmitting power from 58 to the rear PTO shaft 60 is formed. In this embodiment, the gear 60a has a larger diameter than the gear 59a, and the gear train composed of the gears 59a and 60a is a reduction gear train. However, the gears 59a and 60a may have the same diameter, It is conceivable that the diameter of 59a is larger than that of the gear 60a.

  As described above, the PTO drive power system PT2 having the PTO clutch 53 and the PTO speed change / reverse mechanism 55 and transmitting power from the input shaft 21 to the rear PTO shaft 60 is incorporated in the transmission 1. .

  As described above, a PTO clutch switch and a PTO speed change / reverse lever 111 (not shown) are provided in the cabin 103 of the tractor 100, and the PTO clutch 53 of the PTO clutch 53 is operated based on the ON / OFF operation of the PTO clutch switch by the operator. On / off control is performed, and the position of the clutch sliders 55 a, 55 b, and 55 c of the PTO transmission / reverse rotation mechanism 55 is controlled based on the operator's operation of the PTO transmission / reverse rotation lever 111. Thus, with respect to the rear PTO shaft 60, by operating the PTO clutch switch and the PTO shift / reverse lever 111, selection of the driving state / non-driving state, selection of the rotation direction of normal rotation or reverse rotation, and speed during normal rotation It is possible to select the stage (low speed, medium speed, high speed).

  The tractor 100 is connected to and disconnected from the hydraulic pump 12P and the hydraulic motor 12M, the reverser clutch 13, the power steering cylinder 65 for steering the front wheels 9, and the PTO shaft 60 in the HMT that is the main transmission 12 described above. Various hydraulic pressures such as a hydraulic PTO clutch 53, a posture control cylinder 89 for controlling the posture of the work implement attached to the link mechanism 115, a lift cylinder 91 for raising and lowering the work implement attached to the link mechanism 115, etc. Equipment (hydraulic actuator) is equipped. Hereinafter, the configuration of the hydraulic system for driving these hydraulic devices will be described with reference to a hydraulic circuit diagram of the tractor 100 shown in FIG. 3 and an overall view of the transmission 1 shown in FIGS.

  The tractor 100 includes a tandem pump unit 62 including a first hydraulic pump 62a and a second hydraulic pump 62b as a supply source of hydraulic oil and lubricating oil to these hydraulic devices. The tandem pump unit 62 is provided in the transmission 1 as shown in FIGS. 4 to 7, and both pumps 62 a and 62 b are connected to the engine 10 via the input shaft 21 of the transmission 1 and the pump drive gear train 51. Driven by the power of.

  As can be seen from the hydraulic circuit diagram of FIG. 3, the total amount of oil discharged from the first hydraulic pump 21 a is disposed via the pressure oil pipe 63 as shown in FIGS. 4 to 7. To the inlet port 64a. The power steering valve set 64 is provided with power steering hydraulic oil supply / discharge ports 64c and 64d, and these ports 64c and 64d are connected to a power steering cylinder 65 through piping as shown in FIG. Is done. The valves in the power steering valve set 64 are controlled based on the operation of the steering handle 107, whereby the supply and discharge control of the hydraulic oil introduced into the power steering valve set 64 from the inlet port 64a is performed. Done.

  The oil supplied to the power steering valve set 64 and the power steering cylinder 65 is discharged from the outlet port 64b of the power steering valve set 64 and passes through the pressure oil pipe 66, the line filter 67, and the pressure oil pipe 68 as shown in FIG. As shown in FIG. 8, the fuel is supplied to the inlet port 70 a of the traveling valve set 70 provided in the transmission 1.

  As shown in FIG. 3, the travel valve set 70 includes a forward clutch 13F and a reverse clutch 13R of the reverser clutch 13, a front wheel normal speed drive clutch 32L and a front wheel acceleration drive clutch 32H of the drive mode switching clutch 32, and an automatic brake. A hydraulic oil supply / discharge control valve group for the hydraulic cylinders 76L and 76R is incorporated. Each valve included in the hydraulic oil supply / discharge control valve group will be described.

  A reverser clutch direction control valve 71 is provided for hydraulic oil supply / discharge control of the reverser clutch 13 with respect to the forward clutches 13F and 13R. The direction control valve 71 supplies oil to the forward clutch 13F and discharges oil from the reverse clutch 13R, a neutral position for discharging oil from the forward clutch 13F and the reverse clutch 13R, and discharges oil from the forward clutch 13F. Thus, it is possible to switch between three reverse positions for supplying oil to the reverse clutch 13R. Further, the directional control valve 71 is a hydraulic pilot valve, the forward switching valve 72F for applying a pilot pressure for setting the directional control valve 71 to the forward position, and the directional control valve 74 to the reverse position. A reverse switching valve 72R for applying a pilot pressure for setting is provided. The forward switching valve 72F and the reverse switching valve 72R are electromagnetic switching valves controlled by a controller (not shown) based on the operation of the reverser lever 108. Regardless of the position of the directional control valve 71, the clutch valve 73 for releasing oil from the forward clutch 13F and the reverse clutch 13R and separating the clutches 13F and 13R by depressing the clutch pedal 112. Is provided.

  A front-wheel normal-speed drive switching valve 74L is provided for supplying / discharging hydraulic oil to / from the front-wheel normal-speed drive clutch 32L of the drive mode switching clutch 32, and front-wheel acceleration driving is used for supplying / exhausting hydraulic oil to the front-wheel acceleration drive clutch 32H. A switching valve 74H is provided. These switching valves 74L and 74H are electromagnetic switching valves controlled by a controller based on the operation of the drive mode operation tool. Further, a left automatic brake switching valve 75L is provided for supplying and discharging hydraulic oil to and from an automatic brake hydraulic cylinder 76L for operating the brake 17L on the left differential output shaft 26L, and the brake on the right differential output shaft 26R. A right automatic brake switching valve 75R is provided for supplying and discharging hydraulic oil to and from an automatic brake hydraulic cylinder 76R for operating 17R. These switching valves 75L and 75R are electromagnetic switching valves that are controlled by the controller based on the turning operation of the steering handle 107 when the automatic brake setting operation tool is set to automatic brake.

  A relief valve 69 is incorporated in the traveling valve set 70 having the hydraulic oil supply / discharge control valve group as described above, and the relief oil of the relief valve 69 is a charge valve mechanism in the HMT that is the main transmission 12. It is used for supplementing hydraulic fluid in a closed circuit between the hydraulic pump 12P and the hydraulic motor 12M via 12d or 12e. Part of the oil from the inlet port 70a that flows without passing through the relief valve 69 is diverted from the travel valve set 70 to the HMT as the main transmission 12, and is used for controlling the pump swash plate 12b of the HMT. Are supplied to the directional control valve 17e and the hydraulic cylinder 17f constituting the servo mechanism, and the remainder is supplied to the hydraulic oil supply / discharge control valve group in the travel valve set 70.

  The oil used for supplying and discharging the hydraulic oil in the hydraulic oil supply / discharge control valve group of the traveling valve set 70 is supplied to the PTO clutch control valve set 77, and is supplied to the PTO clutch control valve set 77. It is supplied as hydraulic fluid for the PTO clutch 53 via the incorporated valve.

  The oil discharged from the second hydraulic pump 62b is supplied via a pressure oil pipe 82 to an oil passage block 83 for a working machine provided in the transmission 1 as shown in FIGS. The oil in the oil passage block 83 is a working oil pressure control valve set 87 having an external take-out port for hydraulic pressure control (float control or the like) of the working machine, and a hydraulic oil supply / discharge valve set for the attitude control cylinder 89. 88 and the valve set 90 for supplying / discharging hydraulic oil to / from the lift cylinder 91. In FIG. 3, one lift cylinder 91 is shown, but in actuality, a pair of left and right lift cylinders 91 are provided in the transmission 1 as shown in FIGS. 4, 5, 7, 8 and the like. The pair of left and right lift arms 7 is interposed between the boss portion 7c and the pair of left and right lower links 115b. The attitude control cylinder 89 is interposed between the bracket 7b at the tip of one of the left and right lift arms 7 and the lower link 115b on the other side, and the bracket 7b of the other left and right lift arms and the side thereof. A link rod is interposed between the lower link 115b.

  Further, as shown in FIGS. 3 to 7, oil is supplied from the oil passage block 83 of the transmission 1 to the oil cooler 85 disposed in the front portion of the tractor 100 via the oil pipe 84. The oil cooled in step 1 is returned to the pipe joining member 78 provided in the transmission 1 through the oil pipe 86. The pipe joining member 78 is connected to the lubricating oil path to the PTO clutch 53 and the lubricating oil path to the reverser clutch 13 in the transmission 1, and as will be described in detail later, The left and right axles 28L and 28R in the transmission 1 are connected to a pair of left and right lubricating oil pipes 81 (left lubricating oil pipe 81L and right lubricating oil pipe 81R) via a pipe branching member 80. Lubricating oil is supplied to the tapered roller bearings 46 and 47 that support each of them.

  Next, with reference to FIGS. 4 to 12, the arrangement and configuration of each mechanism and member in the transmission 1 will be described, and in particular, from the differential mechanism 15 constituting the rear wheel drive system to the left and right axles 28L and 28R. The support structure of the rear wheel drive system PT1r will be described in detail.

  As shown in FIGS. 4 to 8 and the like, the transmission 1 includes a transmission case 2, an HMT case 3, a rear cover 4, a pair of left and right differential output shaft cases 5 (5L and 5R), and a pair of left and right axle cases 6. (6L · 6R) is combined.

  A block that constitutes the travel valve set 70 is fixed to the left and right outer surfaces (right side in this embodiment) of the front half of the mission case 2 (facing the front chamber 2F described later). The oil passage block 83 and the working machine control hydraulic valve set 87 are mounted on the upper surface of the transmission case 2, and a pair of left and right lift arms 7 are mounted on the rear upper end of the transmission case 2. Yes. The base end portion of each lift arm 7 is pivotally supported by the mission case 2 via a pivot fulcrum shaft 7a extending in the left-right direction, so that the pair of left and right lift arms 7 can pivot in the front-rear direction. It is assumed that it is supported on the case 2.

  A bracket 7b is formed at the tip of each lift arm 7. As described above, one of the lift arms 7 is connected to the lower link 115 on one side of the bracket 7b of the left and right lift arms 7. Further, a posture control cylinder 89 shown in FIG. 3 is connected to the bracket 7b of the other left and right lift arms 7, and a lift (not shown) is connected so as to connect the other lift arm 7 to the lower link 115 on that side. The rod is connected. Further, a boss portion 7c is provided in the middle portion between the base end portion and the distal end portion of each lift arm 7, and the boss portions 7c of the left and right lift arms 7 are provided with the lift arms 7 as described above. 3 is coupled to the left and right lower links 115.

  An HMT case 3 that houses an HMT (not shown in FIGS. 4 to 12) serving as the main transmission 12 is fixed to the front end of the transmission case 2 so as to extend forward. As shown in FIG. 5 and the like, the HMT case 3 supports an input shaft 21 extending in the front-rear direction. The input shaft 21 protrudes forward from the HMT case 3 so as to be connected to the output shaft of the engine 10 via the transmission shaft 11 with a universal joint as described above.

  The mission case 2 is divided into a front chamber 2F and a rear chamber 2R by a vertical partition wall 2a extending in the left-right direction, as can be seen in FIGS. In the front chamber 2F, a reverser clutch 13 and an auxiliary transmission device 14 which are not shown here are accommodated. The sub-transmission output shaft 25 of the sub-transmission device 14 extends in the front-rear direction, and its rear portion is pivotally supported by the partition wall 2 a via the bearing 39. Further, the rear end portion of the auxiliary transmission output shaft 25 is inserted into the rear chamber 2R via the partition wall 2a, and a bevel pinion 25d is formed (or fixed) at the rear end portion. A rear differential mechanism 15 is accommodated in the rear chamber 2R, and a bevel pinion 25d provided at the rear end of the auxiliary transmission output shaft 25 meshes with a bevel ring gear 15a of the rear differential mechanism 15 as shown in FIG. ing.

  As shown in FIGS. 9 to 11, the left and right outer walls of the mission case 2 are provided with a left opening 2d and a right opening 2e so as to define the left and right ends of the rear chamber 2R. Inner end portions (end portions on the mission case 2 side) 5a of the left and right differential output shaft cases 5 are open end portions and bulge in a flange shape. Inner ends 5 a of the left and right differential output shaft cases 5 are joined to the left and right outer walls of the mission case 2 so as to close the openings 2 d and 2 e of the mission case 2. Each brake 17 is fitted in the inner end portion 5 a of each differential output shaft case 5, and is disposed along each of the left and right openings 2 d and 2 e of the mission case 2. That is, the left outer wall around the left opening 2d of the mission case 2 is joined to the inner end 5a, which is the right end of the left differential output shaft case 5L, and the left brake 17L is connected to the left opening 2d of the mission case 2. On the other hand, the right outer wall around the right opening 2e of the mission case 2 is joined to the inner end 5a, which is the left end of the right differential output shaft case 5R, so that the right brake 17R is connected to the mission case 2. Along the right opening 2e.

  As can be seen from FIG. 10, a brake cam shaft 17 b extending in the left-right direction is pivotally supported at the front end portion of the inner end portion 5 a of each differential output shaft case 5. A cam is formed at the inner end of the brake cam shaft 17b, and is linked to the pushing member of each brake 17 in the differential output shaft case 5. The outer end of the brake cam shaft 17 protrudes to the outside of the differential output shaft case 5, and a brake arm 17a is fixed to the protruding outer end. Thus, the brake arms 17a are supported in front of the left and right differential output shaft cases 5L and 5R on both the left and right sides of the transmission 1 so that the brake arms 17a can be pivoted back and forth. In addition, the automatic brake hydraulic cylinders 76L and 76R are linked to each other.

  In the rear chamber 2R, a vertical support wall 2b extends rearward from a substantially central portion on the left and right sides of the partition wall 2a. The rear differential mechanism 15 is arranged on one side of the support wall 2b, that is, between the support wall 2b and one of the left and right openings 2d and 2e. In this embodiment, it is disposed on the right side of the support wall 2b, that is, between the support wall 2b and the right opening 2e. Therefore, the auxiliary transmission output shaft 25 is also pivotally supported via the bearing 39 in the partition 2a on the right side of the support wall 2b. Hereinafter, the arrangement configuration of each member in the rear chamber 2R will be described on the assumption that the rear differential mechanism 15 is thus arranged in the right portion of the rear chamber 2R. However, the arrangement of the rear differential mechanism 15 is not limited to the right-side arrangement as described above, and it is between the support wall 2b and the left opening 2d in the left portion of the rear chamber 2R, or the support wall 2b is eliminated. It is also possible to arrange the rear chamber 2R at the center of the left and right, and the arrangement of other related members (for example, the auxiliary transmission output shaft 25) is appropriately arranged in accordance with the arrangement of the rear differential mechanism 15. Is.

  A support member 15e is fitted into the opening 2e disposed on the right side of the rear differential mechanism 15, and is fixed to the transmission case 2. The right side portion of the rear differential mechanism 15 and the right side difference are located at the center of the support member 15e. A right bearing 41R such as a ball bearing for bearing the dynamic output shaft 26R is fitted. On the other hand, a left bearing 41L such as a ball bearing for supporting the left side portion of the rear differential mechanism 15 and the left differential output shaft 26L is fitted in the support wall 2b disposed on the left side of the rear differential mechanism 15. Yes.

  As shown in FIGS. 10 and 11, the bevel ring gear 15a of the rear differential mechanism 15 is arranged adjacent to the left side of the support member 15e, and is fitted to the right bearing 41R fitted in the center hole of the support member 15e to the right. A central boss portion 15a1 formed on the bevel ring gear 15a in an extending shape is fitted. A bevel pinion 25d at the rear end of the auxiliary transmission output shaft 25 is disposed on the left side of the front end of the bevel ring gear 15a, and meshes with the front end of the bevel ring gear 15a. Behind the bevel pinion 25d, a differential case 15b extends leftward from the bevel ring gear 15a and is fixed to the bevel ring gear 15a with a bolt or the like. A boss portion 15b1 is formed at the left end portion of the differential case 15b so as to extend to the left from the main body portion of the differential case 15b, and the boss portion 15b1 is fitted into the left bearing 41L in the partition wall 15b. .

  The right differential output shaft case 5R supports a right differential output shaft 26R extending in the left-right direction. The right brake 17R is provided around the right differential output shaft 26R. When the inner end 5a (left end) of the right differential output shaft case 5R is joined to the right outer wall of the transmission case 2 as described above, 17R is disposed adjacent to the right side of the support member 15e fitted in the right opening 2e. The inner end portion (left end portion) of the right differential output shaft 26R extends further inward (leftward) than the right brake 17R, and is inserted into the central boss portion 15a1 of the bevel ring gear 15a in the right bearing 41R. The tip portion is disposed in the right portion of the main body portion of the differential case 15b. A right bevel diff side gear 26b is fixed to the inner end (left end) of the right differential output shaft 26R.

  The left differential output shaft case 5L supports a left differential output shaft 26L extending in the left-right direction. The left brake 17L is provided around the left differential output shaft 26L. As described above, when the inner end 5a (right end) of the left differential output shaft case 5L is joined to the left outer wall of the transmission case 2, the left brake 17L 17L is disposed adjacent to the left side of the left opening 2d. The inner end portion (right end portion) of the left differential output shaft 26L extends further inward (rightward) than the left brake 17L, and is inserted into the boss portion 15b1 of the differential case 15b in the left bearing 41R. The part is disposed in the left part of the main body of the differential case 15b. A left bevel differential side gear 26a is fixed to the inner end (right end) of the left differential output shaft 26L.

  A differential pinion shaft 15d is disposed in the main body of the differential case 15b so as to rotate integrally with the differential case 15b, and the bevel differential pinion 15c pivotally supported by the differential pinion shaft 15d is connected to the left and right bevel differential side gears 26a and 26b. Meshed. In the present embodiment, the differential pinion shaft 15d is configured in a cross shape, and the four bevel differential pinions 15c are arranged on the vertical plane in the front-rear direction at equal intervals, and each bevel differential pinion 15c has both left and right bevel differential side gears. Although it is in a state of meshing with 26a and 26b, the arrangement and number of the bevel differential pinions 15c are not limited.

  The slide ring 16a of the differential lock mechanism 16 is mounted on the boss portion 15b1 of the differential case 15b between the support wall 2b and the differential case 15b so as to be slidable in the left-right direction along the boss portion 15b1. The differential lock pin 16b extends rightward from the slide ring 16a, and is fitted into the main body portion of the differential case 15b through a hole formed in the left end portion of the main body portion of the differential case 15b. The differential lock pin 16b slides integrally with the slide ring 16a. When the slide ring 16a is disposed at the differential lock position, the tip (right end) of the differential lock pin 16b is formed on the left differential side gear 26a. The left differential output shaft 26L inserted into the pin hole and fixed to the left differential side gear 26a is locked to the differential case 15b. The fork shaft 40 is supported in a left-right extended shape at the upper part of the rear chamber 2R, and a fork 40a extending from the fork shaft 40 is fitted in an annular groove of the slide ring 16a.

  In the rear chamber 2R, a vertical support wall 2c extending in the left-right direction is formed at the rear end of the support wall 2b. Note that the support wall 2c extends from the rear end of the support wall 2b to the left side opposite to the rear differential mechanism 15 in the left-right direction, thereby removing the rear cover 4 and opening the rear end of the transmission case 2 described later. When the portion 2g is opened, the right side of the support wall 2c formed in the left portion of the rear chamber 2R is open, and the rear differential mechanism 15 disposed in the right portion of the rear chamber 2R is accessible.

  As shown in FIGS. 9 and 10, the rear cover 4 is joined to the rear end of the mission case 2 so as to close the rear end opening 2 g of the mission case 2. A rear PTO shaft 60 extending in the front-rear direction is supported on the rear cover 4 via a bearing 60c such as a ball bearing. In the rear chamber 2R, the front end portion of the rear PTO shaft 60 is pivotally supported on the support wall 2c via a bearing 60b such as a ball bearing. The rear end portion of the rear PTO shaft 60 protrudes rearward from the rear cover 4 and is connected to the input shaft of the work implement connected to the tractor 100 via the work implement mounting link mechanism 115 via a transmission shaft with a universal joint or the like. Thus, the rear end portion of the rear PTO shaft 60 is connected.

  Note that a gear 60 a as shown in FIG. 2 is provided on the rear PTO shaft 60 in the rear portion of the rear wall 2 c of the rear case 2 R of the mission case 2 or in the rear cover 4. PTO transmission shafts 59 and the like that are linked and linked via 59a and 60a are disposed, but these are not shown in FIGS.

  Thus, as shown in FIG. 11, the axial center height of the rear PTO shaft 60 supported by the transmission 1 is substantially the same as the axial center height of the differential output shaft 26 (26L / 26R). As shown in FIGS. 9 and 10, in the state where the transmission 1 is disposed on the left differential output shaft 26 </ b> L immediately on the left side of the rear differential mechanism 15 and the transmission 1 is provided on the tractor 100. It will be arrange | positioned in the left-right approximate center.

  On both the left and right sides of the rear PTO shaft 60, the left and right lift cylinders 91 and lower links 115b in the working machine mounting link mechanism 115 are arranged in the left and right directions from the mission case 2. The extended left and right differential output shaft case 5 (5L and 5R) is disposed close to the rear end. Here, it is assumed that the reduction gear mechanism interposed between the differential output shaft 26 and the axle 28 is disposed in a portion near the inner end of the differential output shaft case 5 in the vicinity of the brake 17. Furthermore, when the reduction gear mechanism is a planetary gear mechanism interposed between the differential output shaft 26 and the axle 28 arranged on the same axis, the reduction gear in the differential output shaft case 5 is used. The housing portion of the gear mechanism swells rearward, which may cause interference with the above-described member in the work machine mounting link mechanism 115 disposed immediately thereafter.

  However, as will be apparent from the following description of the transmission configuration from the differential output shaft 26 to the axle 28, in the present embodiment, the first and second reduction gear mechanisms 18 and 19 are disposed near the hub 28a of the axle 28. Since the differential output shaft case 5 is housed in the portion near the outer end portion and the outer axle case 6, the differential output shaft case 5 is disposed immediately before the lift cylinder 91, the lower link 115 b, and the like in the work machine mounting link mechanism 115. Since the portion near the inner end of the differential output shaft case 5 does not accommodate such a reduction gear mechanism, it is a portion that accommodates only the differential output shaft 26 having a relatively small diameter. Backward bulging is also suppressed. Further, although the planetary gear mechanism is used as the second reduction gear mechanism 19 accommodated in the outer end portion of the differential output shaft case 5, the differential output shaft 26 and the second reduction gear mechanism 19 are interposed between them. The first reduction gear mechanism 18 composed of a flat gear train is configured to be interposed, and this brings about the effect of arranging the second reduction gear mechanism 19 and the axle 28 forward, and the differential output shaft case 5 Not only the portion near the inner end, but also the portion closer to the outer end, and further the axle case 6 arranged on the outer side, can be prevented from bulging backward. For this reason, interference with the work machine mounting link mechanism 115 behind the differential output shaft case 5 and the axle case 6 is avoided.

  The transmission mechanism including the differential output shaft 26, the reduction shaft 27, the axle 28, and the first and second gear mechanisms 18 and 19 on both the left and right sides of the transmission 1 is configured to be symmetrical. 9 to 11, only the transmission mechanism on the right side of the transmission 1 from the right differential output shaft 26R to the right axle 28 is illustrated, but this is shown as representative of the left and right side portions. Hereinafter, the support structure of the transmission mechanism on the left and right sides of the transmission 1 will be described with reference to these drawings.

  The outer ends 5b of the left and right differential output shaft cases 5 (5L and 5R) and the inner ends 6b of the left and right axle cases 6 are joined, and the outer ends of the left and right axle cases 6 (6L and 6R). An oil seal cover 6a is fixed to the left and right axles 28 (28L and 28R) projecting from the left and right outer sides of each oil seal cover 6a, and fixed to each rear wheel 8 at the outer end thereof. A hub 28a is formed.

  As shown in FIGS. 9 to 11, a bearing wall 5 c is formed inside a portion of each differential output shaft case 5 near the outer end portion 5 b. In each differential output shaft case 5, a support member 49 is disposed between the outer end 5b and the bearing wall 5c. The outer end 5b of the differential output shaft case 5 and the inner end 6b of the axle case 6 are open ends, and by joining them, the outer end 5b of the differential output shaft case 5 A continuous opening is formed in the inner end 6 b of the axle case 6, and the outer peripheral edge of the internal gear 19 b of the planetary gear mechanism as the second reduction gear mechanism 19 is fitted into this opening. . The support member 49 and the internal gear 19b are fastened together with the axle case 6 with bolts, whereby the support member 49 and the internal gear 19b are fixed to the differential output shaft case 5 and the axle case 6. .

  In the differential output shaft case 5, a ball bearing 42 is fitted in the bearing wall 5 c, and a ball bearing 43 is fitted in the support member 49. The differential output shaft 26 is inserted into a ball bearing 42 in the bearing wall 5 c, and the outer end thereof is pivotally supported by a ball bearing 43 in the support member 49. A flat gear 18 a is provided on the differential output shaft 26 between the bearing wall 5 c and the support member 49. In this embodiment, the spur gear 18a is formed on the differential output shaft 26. However, the spur gear 18a is a member different from the differential output shaft 26, and the differential output shaft 26 is connected by spline fitting or the like. It is good also as what fixes to an outer peripheral surface. In this way, the outer end of the differential output shaft 26 and the flat gear 18a provided here are supported by the bearing wall 5c and the support member 49 of the differential output shaft case 5 via the left and right ball bearings 42 and 43. ing.

  A portion of the differential output shaft case 5 extending from the bearing wall 5c to the outer end portion 5b in the left-right direction is bulged forward from a portion supporting the differential output shaft 26. Such differential output Corresponding to the shape of the shaft case 5, the support member 49 also bulges forward from the portion where the ball bearing 43 is provided. A ball bearing 44 is fitted to a portion of the bearing wall 5c that bulges forward from the ball bearing 42, while a portion of the support member 49 that bulges forward from the ball bearing 43 is A ball bearing 45 is fitted.

  In front of the spur gear 18a, a spur gear 18b having a diameter larger than that of the spur gear 18a is disposed between the bearing wall 5b and the support member 49, and the central boss portion of the spur gear 18b extends to the left and right sides. It is inserted into the left and right bearings 44 and 45. The flat gear 18a and the flat gear 18b are directly meshed with each other. The support member 49 is inserted with a reduction shaft 27 having a left-right axial center. The reduction shaft 27 is disposed in front of the differential output shaft 26 and parallel to the differential output shaft 26. Yes. The inner part of the reduction shaft 27 (on the side closer to the transmission case 2) is inserted into the boss hole of the flat gear 18b as a gear shaft and fixed to the flat gear 18b by spline fitting. In this way, the inner end portion of the reduction shaft 27 and the flat gear 18b provided here are supported by the bearing wall 5c and the support member 49 of the differential output shaft case 5 via the left and right ball bearings 44 and 45. .

  As described above, by engaging the spur gear 18a provided on the outer end of the differential output shaft 26 and the spur gear 18b provided on the inner end of the reduction shaft 27, the differential output shaft 26 A first reduction gear mechanism 18 that transmits power to the reduction shaft 27 is configured. The first reduction gear mechanism 18 is disposed inside the first differential output shaft case 5 near the outer end portion 5b. In the left-right direction, the left and right outer portions of the transmission case 2 and the hub of the axle 28 are provided. It is arranged at a position approximately in the middle of 28a. This position is located behind the lower link 115b of the working machine mounting link mechanism 115 and the lift cylinder 91, etc., as described above. However, as described above, the speed reduction shaft 27 is located in front of the differential output shaft 26. The portion of the differential output shaft case 5 that is disposed and accommodates the first reduction gear mechanism 18 is also formed so as to bulge forward from the portion that the differential output shaft 26 supports. The portion of the case 5 does not bulge backward to accommodate the first reduction gear mechanism 18, thereby preventing interference between the differential output shaft case 5 and these members for mounting the work implement. It is to be avoided.

  The outer side (the side closer to the axle 28) of the speed reduction shaft 27 protrudes outward from the support member 49, and as described above, the outer end 5b of the differential output shaft case 5 and the inner end 6b of the axle case 6. Are arranged in openings formed in the interior thereof, and a sun gear 19a is formed on the outer portion of the reduction shaft 27. Further, in this opening, a carrier 19d is disposed around the sun gear 19a, and the internal gear 19b is disposed around the carrier 19d. A planetary gear 19c is pivotally supported on the carrier 19d by a pivot shaft 19e extending in the left-right direction parallel to the differential output shaft 26 and the reduction shaft 27. Note that a plurality of planetary gears 19c are preferably provided on one carrier 19d. The planetary gear 19c meshes with the sun gear 19a at its inner peripheral edge and meshes with the internal gear 19b at its outer peripheral edge. Thus, the planetary gear mechanism as the second reduction gear mechanism 19 is configured with the outer portion of the reduction shaft 27 as the sun gear shaft.

  A boss portion 6d is formed at an outer end portion of the axle case 6, and right and left inner and outer tapered roller bearings 46 and 47 are fitted into the boss portion 6d. On the other hand, a boss portion 19d1 is formed at the outer end portion of the carrier 19d, extends outward, and is fitted into the left and right tapered roller bearings 46. The outer portions of the left and right outer tapered roller bearings 47 are covered with the oil seal cover 6a, and an oil seal ring 48 is interposed between the oil seal cover 6a and the tapered roller bearing 47. . The axle 28 is inserted into the oil seal ring 48 fitted in the oil seal cover 6a and the tapered roller bearings 46 and 47 fitted in the boss portion 6d of the axle case 6 as described above, and the inner end portion thereof is inserted. The boss 19d1 of the carrier 19d is fitted by spline fitting.

  In this way, the axle 28 fixed to the carrier 19d is disposed on the same axis as the reduction shaft 27 on the left and right outer sides of the reduction shaft 27 as the sun gear shaft of the second reduction gear mechanism 19. The outer end of the speed reduction shaft 27 and the inner end of the axle 28 are close to each other, and a shim 29 as a thrust bearing is interposed in the gap between them, so that the speed reduction shaft 27 and the axle 28 interfere with each other's rotation. I try not to.

  The second reduction gear mechanism 19 which is a planetary gear mechanism occupies a considerably large space in the radial direction of the reduction shaft 27 as the sun gear shaft. However, since the reduction shaft 27 is disposed in front of the differential output shaft 26 as described above, the second reduction gear mechanism 19 is also eccentrically disposed in front of the differential output shaft 26. Therefore, the outer end portion 5b of the differential output shaft case 5 that houses the second reduction gear mechanism 19 is formed so as to bulge forward from a portion that supports the differential output shaft 26, and The axle case 6 having the inner end 6b joined to the end 5b also supports the axle 28 arranged on the same axis with respect to the speed reduction shaft 27. As viewed from the front, it is deflected to the front. Therefore, the rear end portion of the outer end portion 5b of the differential output shaft case 5 that accommodates the second reduction gear mechanism 19 and the entire axle case 6 also swells rearward as viewed from the axial center position of the differential output shaft 26. Interference with the lower link 115b for mounting the work implement, the lift cylinder 91, and the like, which are not taken out and may come close to the rear, is avoided.

  Here, the power transmission configuration including the differential output shaft 26, the reduction shaft 27, the axle 28, and the first and second reduction gear mechanisms 18 and 19 described above is particularly suitable for the tractor 100 as an application target of the transmission 1. The point that is considered to be of the medium class will be explained.

  As for the speed reduction mechanism, a planetary gear mechanism is used as the second speed reduction gear mechanism 19 that supports the axle 28 in consideration of the support strength required for the axle 28 as the axle of the medium class tractor 100. Since the axial center length of the axle 28 is short, a part of the second reduction gear mechanism 19 is accommodated in the axle case 6 and is located at a position very close to the hub 28a in the left-right direction, that is, away from the transmission case 2. Placed in a different position.

  In order to ensure the reduction ratio required between the differential output shaft 26 and the axle 28 in the medium class tractor 100, the second reduction gear mechanism 19 as the planetary gear mechanism is not sufficient, Since most of the necessary reduction ratio is ensured by the two reduction gear mechanism 19, the reduction ratio to be supplemented by the reduction gear mechanism provided in addition to the second reduction gear mechanism 19 can be small. In addition, the second reduction gear mechanism 19 that is a planetary gear mechanism supports an axle 28 that requires high support strength, and this additional reduction gear mechanism has a differential output shaft 26 that requires less support strength. It only has to be supported. Therefore, in this embodiment, the first reduction gear mechanism 18 which is the additional reduction gear mechanism is formed by inserting flat gears 18a and 18b between the parallel differential output shaft 26 and the reduction shaft 27. Since a flat gear train structure is used and the reduction ratio can be small, the distance between the differential output shaft 26 and the reduction shaft 27 can be reduced, and the first reduction gear mechanism 18 can be made compact. It is said. And, in the case of providing such two reduction gear mechanisms to ensure the reduction ratio, if two planetary gear mechanisms are provided, the cost will increase, but in this embodiment, the first reduction gear mechanism is used. Since the gear mechanism 18 has a flat gear train structure, the cost can be reduced and the gear mechanism 18 can be made suitable for the medium-sized tractor 100.

  Further, the first reduction gear mechanism 18 having this flat gear train structure is provided with a second reduction gear mechanism in order to shorten the axial length of the reduction shaft 27 that also serves as the sun gear shaft of the second reduction gear mechanism 19 that is a planetary gear mechanism. 19 is accommodated in a portion near the outer end 5 b of the differential output shaft case 5 so as to be close to 19. Accordingly, the differential output shaft 26 is considerably long in the axial direction, and the portion of the differential output shaft case 5 that covers the differential output shaft 26 between the inner end 5a and the bearing wall 5c. However, the differential output shaft 26 is longer in the left-right direction due to the longer axial center length. Since this portion only needs to cover the differential output shaft 26, the size of the differential output shaft 26 in the radial direction is narrowed, and thus a compact and simple configuration is obtained. Cost can also be reduced.

  In this way, since the axial length of the differential output shaft 26 is ensured to be large, the radially small portion of the differential output shaft case 5 that accommodates it is configured to be long in the left-right direction. As described above, this contributes to avoiding interference between the differential output shaft case 5 and the work implement mounting member disposed behind the differential output shaft case 5.

  Furthermore, if the first reduction gear mechanism 18 has a flat gear train structure, interference between the housing portion that houses the second reduction gear mechanism 19 that is a planetary gear mechanism and a member for mounting the work implement is prevented. It contributes to securing the structure to avoid. The planetary gear mechanism needs to arrange the sun gear shaft and the output shaft fixed to the carrier on the same axis. If such a planetary gear mechanism is configured using the differential output shaft 26 as the sun gear shaft without the speed reduction shaft 27, the differential output shaft 26 and the axle 28 are arranged on the same axis, and this planetary gear mechanism. The rear end of the housing portion that accommodates the housing also bulges rearward as viewed from the axial center of the differential output shaft 26, and interference with the work implement mounting member should be a problem. The gear mechanism 18 has a reduction shaft 27 disposed in front of the differential output shaft 26 as its output shaft. The second reduction gear mechanism 19 that is a planetary gear mechanism uses the reduction shaft 27 as a sun gear shaft. Therefore, as described above, the second reduction gear mechanism 19 is also deflected forward when viewed from the axial center of the differential output shaft 26, and is outside the differential output shaft case 5 that houses the second reduction gear mechanism 19. The end portion 5b and the rear end portion of the axle case 6 also do not bulge rearward, Is the interference with members for work machine attachment has become what is avoided.

  Next, the bearing support structure of the differential output shaft 26, the reduction shaft 27, and the axle 28 constituting the first reduction gear mechanism 18 and the second reduction gear mechanism 19 and the lubricating oil supply structure for the bearing of the axle 28 will be described. To do. As described above, the ball bearings 42, 43, 44, and 45 are used as bearings that support the flat gears 18a and 18b, the differential output shaft 26, and the reduction shaft 27 that constitute the first reduction gear mechanism 18. . Since the first reduction gear mechanism 18 has a small gear diameter of the flat gears 18a and 18b, and the stress received by the engagement of the flat gears 18a and 18b can be small, a large support strength is not required, and the bearing 42. 43, 44 and 45 can be as simple and inexpensive as ball bearings.

  On the other hand, since the axle 28 is thick in the radial direction and has a short axial center length, it has a shape like a cantilever support, and the stress received from the rear wheel 8 fixed to the hub 28a is also strong, and this is supported by the bearing. Since sufficient strength is required, the tapered roller bearings 46 and 47 are used as described above.

  Since the stress applied to the taper roller bearings 46 and 47 is large, a lot of lubricating oil is required accordingly. On the other hand, in the present embodiment, the positions of the tapered roller bearings 46 and 47 are close to the hub 28a fixed to the wheel, and are greatly separated in the left-right direction from the mission case 2 disposed in the left-right center portion of the tractor 100. Therefore, as the tractor 100 tilts in the left-right direction, the axle case 6 in which the tapered roller bearings 46 and 47 are arranged moves greatly up and down, and from the tapered roller bearings 46 and 47 as the upward movement occurs. There is a high possibility that the lubricating oil will come off. Therefore, a positive lubricating oil supply structure for the tapered roller bearings 46 and 47 is desired.

  Therefore, in this embodiment, as can be seen in FIG. 12 and the like, in the space inside the boss portion 6d of the axle case 6, a distance in the left-right direction is taken between the left and right tapered roller bearings 46, 47, and both bearings 46. Between 47, the clearance space as the lubricating oil reservoir 6e is ensured. As described above, in the transmission 1, the left and right lubricating oil pipes 81 (81 </ b> L and 81 </ b> R) branched from the pipe branching member 80 are extended, and the end portions of the lubricating oil pipes 81 are provided at the upper ends of the axle cases 6. It is connected to the lubricating oil port 6c. The lubricating oil port 6 c communicates with the lubricating oil reservoir 6 e in the axle case 6. Thus, the oil discharged from the second hydraulic pump 62b is supplied to the lubricating oil reservoir 6e via the left and right lubricating oil pipes 81 and the like. More specifically, as described above, the pipe branching member 80 is supplied with oil from the pipe joining member 78 via the lubricating oil pipe 79. In the pipe joining member 78, the oil cooler via the oil pipe 86 is supplied. Since the lubricating oil to the PTO clutch 53 and the lubricating oil to the reverser clutch 13 join together with the oil flow from 85, a sufficient amount of lubricating oil is supplied to the lubricating oil pipes 81L and 81R. Thus, regardless of the swinging of the tractor 100, the lubricating oil reservoir 6e is always supplemented with sufficient lubricating oil, and the tapered roller bearings 46 and 47 are always lubricated with this lubricating oil.

  The oil from the lubricating oil port 6c can be supplied to the second reduction gear mechanism 19 that is a planetary gear mechanism. This may be supplied through the lubricating oil reservoir 6e and the tapered roller bearings 46 and 47, or an oil passage from the lubricating oil port 6c to the second reduction gear mechanism 19 is formed in the axle case 6 for lubrication. It is good also as what supplies oil.

1 Transmission 2 Transmission Case 5 Differential Output Shaft Case 6 Axle Case 6c Lubricating Oil Port 6e Lubricating Oil Pool 15 Rear Differential Mechanism (Differential Mechanism)
18 First reduction gear mechanism 19 Second reduction gear mechanism (planetary gear mechanism)
26 Differential output shaft 28 Axle 28a Hub 46/47 Tapered roller bearing 62 Tandem hydraulic pump set 62a First hydraulic pump 62b Second hydraulic pump 81 (81L / 81R) Lubricating oil pipe

Claims (7)

  A lubricating oil supply structure, wherein a lubricating oil port for supplying oil discharged from a hydraulic pump as lubricating oil to a bearing is provided in a housing that houses an axle and a bearing that supports the axle.   The lubricating oil supply structure according to claim 1, wherein an oil pipe for supplying oil discharged from the hydraulic pump is provided outside the casing, and the oil pipe is connected to the lubricating oil port.   The lubricating oil supply structure according to claim 1, wherein the bearing is a tapered roller bearing.   The lubricating oil supply structure according to any one of claims 1 to 3, wherein a deceleration mechanism having the axle as an output shaft is accommodated in the casing.   The lubricating oil supply structure according to claim 4, wherein the speed reduction mechanism is a planetary gear mechanism.   The lubricating oil supply structure according to any one of claims 1 to 5, wherein a lubricating oil reservoir communicating with the lubricating oil port is provided in the casing in the vicinity of the bearing. The lubricating oil supply structure according to claim 6, wherein a plurality of the bearings are provided, and a gap between the plurality of bearings is used as the lubricating oil reservoir.

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