JP6519872B2 - Tractor body frame - Google Patents

Description

  The present invention relates to a vehicle body frame of a tractor.

  Conventionally, as disclosed in, for example, Patent Document 1, in a tractor used as an agricultural tractor or the like, the left frame and the right frame extended in the front-rear direction and the front ends of the left frame and the right frame are connected A vehicle body frame configured in a letter of "U" in plan view is provided, which comprises a front end frame member extended in the left-right direction. The left side frame and the right side frame are respectively made of a front side frame member and a rear side frame member, and are configured by connecting a rear end portion of the front side frame member and a front end portion of the rear side frame member. That is, the front part of the vehicle body frame is configured by the left and right front side frame members, and the rear part of the vehicle body frame is configured by the left and right rear side frame members. An engine is supported by left and right front side frame members, and the engine is installed in a bonnet mounted on the left and right front side frame members. Further, the left and right front side frame members support a front axle case (front axle drive device) disposed below the front of the engine.

  On the other hand, the rear part of the vehicle body frame supports the floor material of the driving part disposed above and supports the front and rear center portions of the tractor, and the transmission front part to be disposed below the floor material Between the left and right rear frame members. The rear end portion of each rear side frame member is fastened to the left and right side portions of the transmission case of the transmission via left and right fastening pins. Thus, the vehicle body frame and the transmission are integrally connected, and the vehicle body frame supports the components (bonnet, engine, front axle case, driving unit (cabin), etc.) of the front and back and front of the tractor. The transmission supports components of the rear of the tractor (rear axle, work implement coupling device, etc.).

  With regard to the fastening structure of the vehicle body frame to the transmission case, as shown in Patent Document 1, a cylindrical boss member for inserting the fastening pin is provided at the rear end portion of the rear side frame member. A round (that is, having a constant radius of curvature all around the axis of the fastening pin) flange is formed at the outer end of the member, and the outer periphery of the flange is welded to the outer surface of the rear frame member. Was. In addition, a pair of upper and lower boss members are provided on each rear side frame member, and fastening pins inserted into the upper and lower boss members are fitted into the upper and lower portions of the left and right side portions of the transmission case. So, we are trying to stabilize the support of the transmission case by the body frame.

JP, 2010-173602, A

  As described above, the transmission supports the working machine connecting device, and a working machine such as a rotary cultivator is attached thereto. Recently, there is a demand for enlargement of the working machine. However, when the size of the working machine is increased, a high stress is applied to the transmission case, particularly at the portion where the fastening pin is inserted, due to the load of the coupled working machine, and the stress also extends to the boss member through which the fastening pin is inserted. In particular, in the upper and lower boss members of the pair of upper and lower boss members in each rear side frame material, twisting stress tends to be concentrated on the lower front portion thereof, and stress is concentrated on the upper front portion of the lower boss member The welds on the outer periphery of the circular flange present at these locations tend to peel off easily. In order to avoid this, it is conceivable to enlarge the diameter of the fastening pin and the fastening portion of the transmission case to the fastening pin or to make a complicated structure, but this increases the complexity of the processing process of the mission case, etc. It leads to the cost. Therefore, there has been a limit to increasing the specs of a tractor that enables mounting of a large work machine.

  Therefore, in the present application, a vehicle body frame structure capable of coping with the stress concentration on the boss member as described above at low cost is provided without complex processing of the fastening portion of the transmission case that causes high cost. It is an object of the present invention to be able to provide a low-cost tractor with high specifications that can also be fitted with a large work machine.

As means for solving the above-mentioned problems, a vehicle body frame of a tractor according to the present invention is provided.
According to the first aspect of the present invention, the vehicle body frame has a left side frame and a right side frame extended in the longitudinal direction of the tractor, wherein the left side frame and the right side frame are respectively made of a front side frame member and a rear side frame member The rear end portion of the front side frame member and the front end portion of the rear side frame member are connected, and the engine is supported by the front side frame member of the left side frame and the right side frame; And a pair of upper and lower boss members are fixed at the rear end portion of the rear side frame member of each of the right side frame, and the rear end of the rear side frame member via a fastening pin inserted in the boss member Part is fastened to the transmission case, and a pair of upper and lower reinforcing frame members are bridged between the rear side frame member of the left side frame and the rear side frame member of the right side frame, Of the pair of upper and lower reinforcement frames, the left and right ends of the upper reinforcement frame are It is a portion near the front of the upper boss member and is connected to a portion of the upper boss member having substantially the same height as that of the upper boss member, and the left and right ends of the lower reinforcing frame are A portion in the vicinity of the front of the lower boss member at the same height as that of the lower boss member, and a flange is formed on each of the boss members; The outer peripheral surface of the flange is welded and fixed to the outer surface of the rear side frame member, and the shape of the outer peripheral edge concentrically surrounds the fastening pin with a constant radius of curvature centering on the axial center of the fastening pin And an extending portion which is longer than the radius of curvature of the arc-like portion in the radial direction centering on the axial center of the fastening pin and is extended so as to project from the arc-like portion. An upper boss member of the pair of upper and lower boss members The extended portion of the outer peripheral edge of the flange extends forward and downward from the axial center of the fastening pin, and the extended portion of the outer peripheral edge of the flange of the lower boss member is forwardly upward from the axial center of the fastening pin It is stretched to

In the second aspect of the present invention, the outer peripheral shape of the flange is an egg shape having an arc-shaped portion smaller in diameter than the arc-shaped portion at the tip of the extension portion opposite to the arc-shaped portion. .

In Claim 3, the bridge-like frame material is constructed between the rear side frame material of the left side frame and the rear side frame material of the right side frame, and the bridge-like frame material is the left side frame and the above It is disposed immediately behind an engine supported by the front side frame member of the right side frame .

  In the vehicle body frame of the tractor according to the present invention, a pair of upper and lower reinforcing frame members are constructed between the rear side frame member of the left side frame and the rear side frame member of the right side frame, and connection of the left and right ends to the rear side frame member By arranging the portions near the front of each boss member at substantially the same height as the boss member, the supporting force of the rear frame member by the reinforcing frame member effectively extends to the boss member, and the fastening pin from the transmission case side It is possible to provide the boss member with a support strength that resists the bending stress applied to the boss member, and to increase the feasibility of the high specsification of the tractor at low cost as described above.

  In addition to the arc-shaped portion having a constant radius of curvature centered on the axial center of the conventional fastening pin, the outer peripheral edge of the flange of the boss member as described above, as in the stretched portion as described above. With such a shape, if the direction of the extended portion is set in consideration of the stress concentration direction to the boss member, it is possible to avoid the stress concentration on the welding portion of the flange outer peripheral edge to the rear side frame material. Therefore, the support strength of the fastening portion of the vehicle body frame to the transmission case can be secured by the low-cost technical means of changing the shape of the flange of the boss member as described above. The feasibility of specification can be further enhanced.

  As described above, the flange outer peripheral edge of the extended portion is formed by setting the extending direction of the extended portion of the outer peripheral edge of the flange to the front lower side in the upper boss member and the front upper side in the lower boss member. It will be arrange | positioned avoiding the stress concentration site | part to a boss member, and the effect of the above-mentioned invention can be implement | achieved.

  In addition, by forming the flange outer peripheral edge having the extension portion as described above into a simple egg shape, the shape processing can be simplified and the processing cost can be suppressed.

  Further, by bridging the above-mentioned bridge-like frame members between the left and right side frame members, the support strength of the engine in the vehicle body frame can be increased, while the support effect can be exerted on the boss members, The strength of supporting the transmission case by the body frame can be further enhanced.

It is a side view of tractor 100 provided with transmission 1 concerning an example of the present invention. FIG. 2 is a skeleton diagram showing a power system of a tractor 100. FIG. 3 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. 2 is a side view of the transmission 1; FIG. 2 is a plan view of the transmission 1; FIG. 2 is a rear view of the transmission 1; FIG. 7 is a plan cross-sectional view of the transmission 1 taken along line AA in FIG. It is plane | planar sectional drawing of the transmission 1 by the BB arrow in FIG. It is back surface sectional drawing of the transmission 1 by CC arrow in FIG. FIG. 7 is a partial rear sectional view of the transmission 1 as viewed in the direction of arrows DD in FIG. FIG. 2 is a perspective view of a vehicle body frame 101. FIG. 3 is a perspective view of the vehicle body frame 101 in a state in which the engine 10 and the front axle drive case 20 are supported and connected to the transmission case 2 (hereinafter referred to as “engine support state”). 15 (a) is a left side view of the vehicle body frame 101, and FIG. 15 (b) is a left side view of the vehicle body frame 101 in a supported state such as an engine. 16 (a) is a right side view of the vehicle body frame 101, and FIG. 16 (b) is a right side view of the vehicle body frame 101 in a supported state such as an engine. FIG. 17 (a) is a front view of the vehicle body frame 101, and FIG. 17 (b) is a front view of the vehicle body frame 101 in a supported state such as an engine. FIG. 18A is a rear view of the vehicle body frame 101, and FIG. 18B is a rear side view of the vehicle body frame 101 in a supported state such as an engine. 19 (a) is a plan view of the vehicle body frame 101, and FIG. 19 (b) is a plan view of the vehicle body frame 101 in a supported state such as an engine. FIG. 20 (a) is a bottom view of the vehicle body frame 101, and FIG. 20 (b) is a bottom view of the vehicle body frame 101 in a supported state such as an engine. It is side surface sectional drawing of the vehicle body frame 101 by EE arrow in Fig.19 (a). FIG. 10 is an enlarged side view of a portion of the vehicle body frame 101 on which a fastening boss member is attached to the transmission case 2; FIG. 16 is an enlarged rear sectional view of the fastening portion of the vehicle body frame 101 to the transmission case 2 as viewed from the arrow G-G in FIG.

  The entire structure of a tractor 100 shown in FIGS. 1 and 2 will be described as an embodiment of a vehicle to which the present invention is applied. In FIG. 1 and FIG. 2, the arrow F indicates the front of the tractor 100, and the arrow F in FIGS. 4 to 7, 9, and 10, which will be described later, 8 shows the front of the tractor 100 and the transmission 1 in the case of FIG. The positions and directions of the respective members and portions mentioned in the following description of the tractor 100 and the transmission 1 assume that the arrow F is directed forward.

  As shown in FIG. 1, the tractor 100 is provided with a vehicle body frame 101. A front axle drive case 20 is supported at the front of the vehicle body frame 101, and the left and right front wheels 9 are supported by the front axle drive case 20. A bonnet 102 is mounted above the front of the vehicle body frame 101, and an engine 10 shown in FIG. 2 is disposed in the bonnet 102. As shown in FIG. 1, a cabin 103 is mounted on the rear upper side of the vehicle body frame 101 at the rear of the bonnet 102.

  As shown in FIG. 1, the rear end portion of the vehicle body frame 101 is connected to the transmission case 2 of the transmission 1 below the cabin 103. The transmission 1 supports the axles 28 (left axle 28L and right axle 28R, see FIG. 4 etc.) of the left and right pair of rear wheels 8 and also outputs front wheel drive power to the front axle drive case 20. The drive shaft 34 (see FIG. 2) is supported. The transmission 1 supports a rear PTO shaft 60 (see FIGS. 2 and 4 and the like) at the rear. The rear PTO shaft 60 drives a working machine such as a rotary cultivator mounted on the tractor 100 through the link mechanism 115. A top link 115a and a pair of left and right lower links 115b extend rearward from the rear end of the transmission case 2 of the transmission 1. A three-point link type work machine mounting link is formed by these links 115a and 115b. The mechanism 115 is configured.

  As shown in FIG. 1, a seat 105 is disposed in a driver's cabin constituted by a cabin 103, and a steering handle 107 extends from an upper portion of a front column 106 erected in front of the seat. In the vicinity of, the forward / reverse switching (reverser) lever 108 is disposed. In the vicinity of the left and right sides of the seat 105, in addition to the main shift lever 109, the sub shift lever 110, and the PTO shift / reverse lever 111, a work implement lifting operation switch, a PTO clutch switch and the like are provided. A clutch pedal 112 extends downward from the front column 106, and an accelerator pedal 113 and a pair of left and right brake pedals (not shown) are provided on a floor surface of the front column 106. Further, a diff lock pedal 114 is provided on a portion of the floor surface closer to the seat 105. In addition, on the top of the front column 106 provided in the front of the cab, there are disposed various operation instruments such as switches for setting the two-wheel / four-wheel drive mode, front wheel acceleration setting, etc. It is done.

  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 PT1 for transmitting power to the rear wheel 8 and the front wheel 9 and a power system for driving a working 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 a transmission shaft 11 with a universal joint.

  The driving power system PT1 has a main transmission 12, a reverser clutch 13 and an auxiliary transmission 14 as a common drive system PT1m for transmitting power distributed to the front wheels 8 and 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. Furthermore, the driving power system PT1 serves as a rear differential drive mechanism 15, a differential lock mechanism 16, and a pair of left and right 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. A front wheel drive gear mechanism is provided as a front wheel drive system PT1 f that includes the brake 17, the first reduction gear mechanism 18, the second reduction gear mechanism 19 and the like, and distributes the output of the auxiliary transmission 14 to the axles 9a of the left and right front wheels 9. 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 are provided.

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

  The structure of each component of the driving power system PT1 in the transmission 1 will be described in detail with reference to FIG. First, in the common drive system PT1m, in the present embodiment, the hydraulic mechanical continuously variable transmission (hereinafter, "HMT") is used as the main transmission 12. The HMT as the main transmission 12 has an axial piston hydraulic pump 12P, and an axial piston hydraulic motor 12M driven by receiving the supply of hydraulic fluid from the hydraulic pump 12M. The HMT has a pump shaft 12a disposed coaxially with the input shaft 21 and rotatably coupled to the input shaft 21 integrally with the input shaft 21. The hydraulic pump 12P and the hydraulic motor 12M are arranged on the same axis on the pump shaft 12a. Further, the HMT is provided with a pump swash plate 12b which is a movable swash plate for setting the volume of the hydraulic pump 12P, and a motor swash plate 12c which is a fixed swash plate which defines the volume of the hydraulic motor 12M. There is. The output shaft 22 of the main transmission 12 is a cylindrical member extending in the front-rear direction coaxially with the input shaft 21, and is disposed around the input shaft 21 so as to be rotatable relative to the input shaft 21. It is set up. The motor swash plate 12 c is coaxially disposed on 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 decelerating 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 It is possible to tilt in the speed increasing tilt direction opposite to the speed reducing tilt direction. 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, and the tilt angle of the pump swash plate 12b is When it is 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 from the position of the tilt angle 0 in the decelerating tilt direction, 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 decelerating tilt direction The rotational speed of 12 c and the output shaft 22 is zero. On the other hand, when the pump swash plate 12b is tilted from the position of the tilt angle 0 in the acceleration tilt direction, the rotational speeds of the motor swash plate 12c and the output shaft 22 increase and reach the maximum tilt angle in the acceleration tilt direction. The rotational speeds of the motor swash plate 12c and the output shaft 22 become maximum (for example, twice the rotational speed 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 the operation of the main shift lever 109. The main shift lever 109 can be tilted from the zero speed position to the maximum speed position. When the main shift lever 109 is in the zero speed position, the pump swash plate 12b is tilted to the maximum tilt angle position in the deceleration tilt direction, and the motor swash plate 12c and the output shaft 22 are rotated regardless of the rotation of the engine 10. The rotational speed is 0. As the main shift lever 109 is tilted from the zero speed position to the maximum speed position, the pump swash plate 12b decreases the tilting angle from the maximum tilting angle position to the tilting angle 0 position in the deceleration tilting direction, and eventually tilts. When the main shift lever 109 reaches the maximum speed position, it reaches the maximum tilt angle position in the acceleration tilt direction when the main shift lever 109 reaches the maximum velocity position.

  The depression angle and direction of the pump swash plate 12b are also controlled by depressing the accelerator pedal 113. That is, as the depression amount of the accelerator pedal 113 is increased, the engine rotational speed is increased, while the pump swash plate 12b is accelerated from the maximum inclination angle position for deceleration in accordance with the increase in the engine rotational 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 to correspond to the engine rotational speed .

  The transmission 1 is provided with a reverser clutch shaft 23 extending in the front-rear direction parallel to the input shaft 21 and the output shaft 22 of the main transmission 12, an idle shaft 24 and an auxiliary transmission output shaft 25. 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 mounted on the reverser clutch shaft 23 via the reverser clutch 13. The flat gear 13a is in direct mesh with the flat gear 22a, and the flat gears 22a and 13a constitute a forward gear train. The flat gear 13b meshes with the flat gear 22b through an idle gear 24a supported on an idle shaft 24, and the flat gears 22b, 24a, and 13b constitute a reverse gear train.

  The reverser clutch 13 engages the forward clutch 13F and separates the reverse clutch 13R by operation of the reverser lever 108, reverses the forward clutch 13F and separates the forward clutch 13F, and forward clutch 13F and reverse. The clutch 13R is set to one of three states in a neutral state in which the clutches 13R are separated from each other. When the reverser clutch 13 is set in the forward state, the rotational power of the output shaft 22 of the main transmission 12 is transmitted to the reverser clutch shaft 23 through the forward gear train composed of the flat gears 22a and 13a, and the reverser clutch shaft 23 rotates in the forward direction. When the reverser clutch 13 is set to the reverse state, the rotational power of the output shaft 22 of the main transmission 12 is transmitted to the reverser clutch shaft 23 through the reverse gear train composed of the flat 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.

  A low speed gear train, a medium speed gear train, and a high speed gear train, which constitute a gear type stepped transmission as the auxiliary transmission 14, are interposed between the reverser clutch shaft 23 and the auxiliary transmission output shaft 25. That is, flat gears 23a, 23b and 23c are fixed to the reverser clutch shaft 23, flat gears 25a, 25b and 25c are mounted on the auxiliary transmission output shaft 25 so as to be relatively rotatable, and the flat gears 23a and 25a are The low gear train is directly meshed to form a low speed gear train, and the spur gears 23b and 25b are directly meshed to form a medium speed gear train, and the spur gears 23c and 25c are directly meshed to form a high speed gear train. On the auxiliary transmission output shaft 25, the clutch slider 14a is slidable between the spur gears 25a and 25b, and the clutch slider 14b is slidable along the auxiliary transmission output shaft 25 in the vicinity of the spur gear 25c. The auxiliary transmission output shaft 25 is provided so as to be incapable of relative rotation (integrally rotatable). The clutch sliders 14a and 14b are slide operated by the operation of the auxiliary transmission lever 110, and any one of the spur gears 25a, 25b and 25c meshes with the auxiliary transmission output shaft 25 via the clutch slider 14a or 14b. Do.

  That is, the auxiliary transmission 14 engages the clutch slider 14a with the spur gear 25a to transmit power from the reverser clutch shaft 23 to the auxiliary transmission output shaft 25 via the low speed gear train composed of the spur gears 23a and 25a. In the intermediate gear state, the clutch slider 14a is engaged with the spur gear 25b, and power is transmitted from the reverser clutch shaft 23 to the auxiliary transmission output shaft 25 via the medium gear train consisting of the spur gears 23b and 25b. And a high speed gear state in which the clutch slider 14b is engaged with the flat gear 25c and power is transmitted from the reverser clutch shaft 23 to the auxiliary transmission output shaft 25 via the high speed gear train composed of the flat gears 23c and 25c. It is set to one of the speed stages. Since the rotation direction of the reverser clutch shaft 23 is set to the forward direction or the reverse direction by switching of the reverser clutch 13, the stepless transmission of the main transmission 12 and the high, middle, and low three-speed transmissions of the auxiliary transmission 14 A wide and detailed shift effect can be obtained both at the forward setting and at the reverse setting. It is also possible to set the auxiliary transmission 14 in a neutral state in which all the spur gears 25a, 25b, 25c are not engaged with the clutch sliders 14a, 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 which is an input gear of the rear differential mechanism 15. On the other hand, a flat gear 25e is fixed at the front end portion of the auxiliary transmission output shaft 25, and the flat gear 25e is formed by a flat gear 31a fixed to the counter shaft 31 constituting the front wheel drive gear mechanism 30. It is directly meshed. 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. Incidentally, a member 25f illustrated to be related to the flat gear 25e in FIG. 2 is a rotational speed detection member, and based on the rotational speed of the transmission output shaft 25 detected by the rotational speed detection member 25f, The on / off control and the like of the front wheel speed increasing clutch 32H are performed.

  The rear differential mechanism 15 of the rear wheel drive system PT1r includes the bevel ring gear 15a, a differential case 15b fixed on one side of the bevel ring gear 15a, a bevel differential pinion 15c disposed in the differential case 15b, and a bevel differential pinion 15c. And 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 axial center in the left and right direction (this embodiment) In this case, the differential case 15b is mounted on the right differential output shaft 26R so as to be relatively rotatable, and the differential case 15b has boss portions 15b1 formed on the left and right ends opposite to the bevel ring gear 15a. 26 (26L, 26R) is rotatably mounted on the other (the left differential output shaft 26L in this embodiment). The inner ends of both differential output shafts 26 (26L, 26R) are disposed in the differential case 15b, and the bevel differential side gears 26a, 26b are fixed to the inner ends of the differential output shafts 26L, 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. In the bevel differential side gear 26a of the differential output shaft 26L of the pair of bevel differential side gears 26a and 26b to which the boss portion 15b1 of the differential case 15b is attached, a hole for inserting a differential lock pin 16b described later is formed. ing.

  The rear differential mechanism 15 is provided with a differential lock mechanism 16. The differential lock mechanism 16 has a slide ring 16a slidably mounted on the boss 15b1 of the differential case 15b in the axial direction, and a laterally extending differential lock pin 16b fixed to the slide ring 16a. There is. The main body of the differential case 15b is provided with a hole, and the tip of the differential lock pin 16b inserted through the hole is disposed in the main portion of the differential case 15b. The slide ring 16 a is set to either the unlocked position away from the main body of the differential case 15 b or the differential lock position close to the main body of the differential case 15 b by the sliding thereof. When the slide ring 16a is disposed at the differential lock position, the distal end of the differential lock pin 16b extended from the slide ring 16a passes through the hole of the bevel differential side gear 26a of the differential output shaft 26L on which the differential case 15b is mounted. The differential case 15b is locked to the differential output shaft 26L, whereby the left and right differential output shafts 26L and 26R are differentially locked (in a non-differential state). When the slide ring 16a is in the unlocked position, the end of the differential lock pin 16b is retracted from the bevel differential side gear 26a, and the differential output shafts 26L and 26R are made differentialable.

  Although it is omitted in FIG. 2, as can be seen in FIG. 11, the left and right extending fork shaft 40 is extended in the transmission case 2 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 and right direction), and the slide ring 16 a slides through the fork 40 a by the slide and is disposed at the diff lock position or the lock release position. Ru. Further, the fork shaft 40 and the fork 40a are biased by the spring 40b wound around the fork shaft 40 in the direction to arrange the slide ring 16a in the unlocked position. The fork shaft 40 is slid by the operation of the differential lock pedal 114. When the diff lock pedal 114 is not depressed, the slide ring 16a is in the unlocked position, and when the diff lock pedal 114 is depressed, the slide ring 16a is disposed in the diff lock position.

  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) based on FIG. 2 The configuration of the part of will be described. Hereinafter, in the description of the structure of the rear wheel drive system PT1r, the rear differential mechanism 15 side is “inside” in the axial center direction (left and right direction) of each differential output shaft 26, and the opposite side to the rear differential mechanism 15; Is referred to as the "outside". In FIG. 2, the portion from the rear differential mechanism 15 to the left axle 28 (28 L) of the rear wheel drive system PT 1 r is illustrated, and the outside portion of the right differential output shaft 26 R, the reduction shaft 27 on the right, and the right The first right reduction gear mechanism 18 interposed between the outer portion of the differential output shaft 26R and the right reduction shaft 27, the second right reduction gear mechanism 19 and the right axle 28 (28R) It is omitted.

  Brakes 17 (left brake 17L and right brake 17R (see FIGS. 9, 10, and 11)) are provided on inward portions of the differential output shafts 26. The left and right brakes 17L and 17R are operated separately by stepping on the pair of left and right brake pedals (not shown) provided in the cabin 103 as described above. The left and right brakes 17L and 17R can also be operated by the automatic brake hydraulic cylinders (hydraulic actuators) 72L and 72R shown in FIG. 3 as described later, in addition to the depression operation of the brake pedal by such an operator. . This is because when the steering handle 107 is turned for turning the vehicle when an operation tool such as an automatic brake setting switch (not shown) provided in the cabin 103 is set to the automatic brake setting, the brake 17 inside the turn is turned on. The hydraulic cylinder 76L or 76R is operated to apply the brake 17 and to brake the rear inner wheel 8 on the inside of the turn so that the tractor 100 can make a small turn. As a structure for small turning of the tractor 100, the speed of the front wheel 9 is higher than that of the rear wheel 8 at the time of turning, as described later, other than the automatic brake system for braking the rear wheel 8 inside the turning in this way. Front wheel acceleration system is also provided.

  At the outer end of each differential output shaft 26, a spur gear 18a is fixed (or formed). A pair of left and right decelerating shafts 27 which extend in the left and right direction are disposed in parallel with the outside 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 18 b having a diameter larger than that of the flat gear 18 a is fixed (or formed) on the outer periphery thereof. The spur gear 18b is directly meshed with the spur gear 18a of each differential output shaft 26, and is interposed between each differential output shaft 26 and each reduction shaft 27 by the spur gears 18a and 18b. The first reduction gear mechanism 18 is configured.

  The left and right axles 28 (28L and 28R) are disposed on the outer sides of the left and right decelerating shafts 27 coaxially with the decelerating shafts 27, respectively, and between the decelerating shafts 27 and the axles 28, a second A reduction gear mechanism 19 is interposed. While the first reduction gear mechanism 18 is formed by meshing the small and large diameter flat gears 18a and 18b, 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 which is the second reduction gear mechanism 19, and a sun gear 19 a is fixed (or formed) thereon. Around the sun gear 19a, an internal gear 19b fixed to the inner circumferential surface of the after-mentioned 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 planet gear 19c is pivotally supported by a carrier 19d, which is fixed to the inner end of the axle 28. The planet gears 19c meshing with the sun gear 19a and the internal gear 19b revolve around the sun gear 19a as the sun gear 19a rotates, and the carrier 19d and the axle 28 rotate by the revolution of the planet 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. The rotary 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 wheel of such a configuration The drive system PT1 r is all incorporated in the transmission 1 as described above.

  The structure of the portion of the front wheel drive system PT1f from the front wheel drive shaft 34 through the front differential mechanism 36 to the axles 9a of the left and right front wheels 9 is as described above. Here, the transmission of the front wheel drive system PT1f The configuration of the part incorporated in 1 will be described. The spur gears 25e and 31a constitute a reduction gear train for transmitting the rotational power of the auxiliary transmission output shaft 25 to the counter shaft 31. The front gear drive clutch shaft 33 has flat gears 31b and 31c fixed to the counter shaft 31 and is disposed parallel to the counter shaft 31. The front wheel normal speed drive clutch 32L and the front wheel acceleration drive clutch 32H A drive mode switching clutch 32 of an integrated structure is provided. The spur gears 32 a and 32 b are mounted on the front wheel drive clutch shaft 33 via the drive mode switching clutch 32. The flat gear 32a is directly meshed with the flat gear 31b, and the flat gears 31b and 32a constitute a front-wheel normal speed drive gear train. The flat gear 32b is in direct mesh with the flat gear 31c, and the flat gears 31c and 32b constitute a front wheel acceleration drive gear train. The front wheel acceleration drive gear train has a smaller output / input gear diameter ratio than the front wheel normal speed drive gear train.

  The drive mode switching clutch 32 operates the front wheel normal speed drive clutch 32L by the operation of the drive mode / front wheel acceleration setting operation tool (hereinafter referred to as "drive mode operation tool" not shown) and the steering handle 107. The normal four-wheel drive state in which the front wheel acceleration drive clutch 32H is separated and 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 connected and both clutches 32L and 32H It is set to any one of the two-wheel drive state which is separated. On the other hand, regarding the power transmission state to the front wheels 9, one of the two-wheel drive mode, the normal four-wheel drive mode, and the front wheel acceleration mode is set by the operation of 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 wheel 107, and the rotational power of the counter shaft 31 is formed by the flat gears 31b and 32a. It 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 the normal speed. Thereby, the front wheel 9 is rotationally driven at a speed substantially synchronized with the rear wheel 8.

  In the state where the front wheel acceleration mode is set, when the steering handle 107 is turned for turning the vehicle, 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 through the front wheel acceleration drive gear train consisting of the flat gears 31c and 32b, and the rotation of the front wheel drive clutch shaft 33 is accelerated. Ru. As a result, the rotational speed of the front wheel 8 is higher than that of the rear wheel 7, and the tractor 100 can make a small turn without damaging the field. On the other hand, even when the front wheel acceleration mode is set, the drive mode switching clutch 32 is normally set to the four-wheel drive state and the front wheel 9 substantially synchronizes with the rear wheel 8 as long as the steering wheel 107 is in the straight ahead position. Drive by rotation.

  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 is also conceivable to transmit some power to the front wheel drive clutch shaft 33 by setting the front wheel normal speed drive clutch 32L to a half clutch state.

  A flat gear 33a is fixed (or formed) to the front wheel drive clutch shaft 33, and is directly meshed with the flat gear 34a fixed (or formed) to the front wheel drive shaft 34. The spur 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.

  The description of the structure of the traveling power system PT1 shown in FIG. 2 is as described above. Next, the structure of the PTO drive power system PT2 shown in FIG. 2 will be described. The gears 51a and 51b are fixed to the 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 through the pump drive gear train 51 composed of the gears 21a, 51a, 51b and 51c. A tandem hydraulic pump set 62 is connected to the pump drive shaft 52. Thus, 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 62a and 62b of the tandem hydraulic pump set 62 are configured to be driven by the power of the engine 10. ing.

  The cylindrical PTO drive shaft 50 is provided so as to be rotatable relative to the PTO clutch shaft 54. A hydraulic PTO clutch 53 is interposed between the PTO drive shaft 50 and the PTO clutch shaft 54. There is. The rotational power of the input shaft 21 is transmitted to the pump drive shaft 52 via the pump drive gear train 51 (gears 21a, 51a, 51b, 51c) regardless of the engagement and disengagement of the PTO clutch 53, while the gear The rotational power of the input shaft 21 transmitted to the PTO drive shaft 50 via the 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. Be done. The PTO gear shift / reverse gear mechanism 55 includes a PTO gear shift drive shaft 56 connected integrally rotatably on the same axis to the PTO clutch shaft 54, a PTO gear shift driven shaft 57 parallel to the PTO gear shift drive shaft 56, and The idle shaft 58 is composed of a plurality of PTO transmission gear trains and a PTO reverse gear train which are interposed between the PTO transmission drive shaft 56 and the PTO transmission driven shaft 57.

  That is, in the PTO gear shift / reverse gear mechanism 55, the PTO gear shift drive shaft 56 is fixedly formed (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). In the PTO transmission 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 relatively rotatably mounted. 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 drive gear 56c and the high-speed driven gear 57c are directly meshed to form a PTO high-speed gear train. With these three gear trains, the PTO gear shift / reverse gear mechanism 55 has three forward rotation PTOs. A transmission gear train is configured. On the other hand, the reverse rotation drive gear 56d and the reverse rotation driven gear 57d are meshed via the idle gear 58a on the idle shaft 58, and the PTO reverse gear in the PTO gear shift / reverse gear mechanism 55 is formed by these gears 56d, 58a and 57d. The columns are organized.

  Further, the PTO gear shift / reverse gear mechanism 55 links the drive 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 to the PTO transmission driven shaft 55. Clutch sliders 55a, 55b, and 55c. That is, the clutch slider 55a is between the low-speed and medium-speed driven gears 57a and 57b, the clutch slider 55b is near the high-speed driven gear 57c, and the clutch slider 55c is non-rotatable relatively near the reverse rotation driven gear 57d. The PTO transmission driven shaft 57 is mounted slidably in the center direction. When any one of the clutch sliders 55a, 55b, 55c engages with one of the driven gears 57a, 57b, 57c, 57d, the rotational power of the PTO transmission drive shaft 56 via the corresponding gear train. Is transmitted to the PTO transmission driven shaft 57.

  A PTO transmission shaft 59 coaxial with the PTO transmission driven shaft 57 is connected to the PTO transmission driven shaft 57 so as to be integrally rotatable with the PTO transmission driven shaft 57. The rear PTO shaft 60 extends parallel to the PTO transmission shaft 59, and the gear 58a fixed to the PTO transmission shaft 58 and the gear 60a fixed to the rear PTO shaft 60 are engaged with each other to make the PTO transmission shaft A gear train for transmitting power from the rear PTO shaft 58 to the rear PTO shaft 60 is configured. In this embodiment, the gear 60a has a diameter larger than that of 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 have the same diameter, or It is also conceivable to make 59a larger in diameter than the gear 60a.

  As described above, the PTO drive power system PT2 configured to transmit power from the input shaft 21 to the rear PTO shaft 60 including the PTO clutch 53 and the PTO shift / reverse mechanism 55 is incorporated in the transmission 1 .

  As described above, the PTO clutch switch and the PTO gear shift / reverse lever 111 (not shown) are provided in the cabin 103 of the tractor 100, and the PTO clutch 53 is provided based on the ON / OFF operation of the PTO clutch switch of the operator. The on / off control is performed, and the position control of the clutch sliders 55a, 55b, 55c of the PTO shift / reverse mechanism 55 is performed based on the operation of the PTO shift / reverse lever 111 by the operator. Thus, with regard to the rear PTO shaft 60, selection of the drive state / non-drive state, selection of the rotational direction of forward rotation or reverse rotation, and speed at normal rotation by operation of the PTO clutch switch and the PTO shift / reverse lever 111 It is possible to select the stage (low speed, medium speed, high speed).

  The tractor 100 performs disconnection and connection of power transmission to the hydraulic pump 12P and the hydraulic motor 12M, the reverser clutch 13 and the power steering cylinder 65 for steering the front wheel 9 and the PTO shaft 60 in the HMT which is the above-mentioned main transmission 12 Various hydraulics such as a hydraulic PTO clutch 53, a posture control cylinder 89 for controlling the posture of the working machine mounted on the link mechanism 115, and a lift cylinder 91 for lifting and lowering the working machine mounted on the link mechanism 115 Equipment (hydraulic actuator) is equipped. The configuration of the hydraulic system for driving these hydraulic devices will be described below based on the hydraulic circuit diagram of the tractor 100 shown in FIG. 3 and the general view of the transmission 1 shown in FIGS. 4 to 8.

  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 the hydraulic devices. The tandem pump unit 62 is provided in the transmission 1 as shown in FIGS. 4 to 7, and both the pumps 62a and 62b are connected to the engine 10 through the input shaft 21 of the transmission 1 and the pump drive gear train 51. The engine is driven by receiving the power of the vehicle, and sucks the oil from the oil tank constituted by the oil reservoir of the transmission case 2 and an oil reservoir provided separately via the line filter 61.

  As can be seen from the hydraulic circuit diagram of FIG. 3, the entire discharge oil of the first hydraulic pump 62 a is disposed through the pressure oil pipe 63 as shown in FIGS. 4 to 7. Supply port 64a. The power steering valve set 64 is provided with power steering hydraulic oil supply and discharge ports 64c and 64d, and these ports 64c and 64d are connected to the power steering cylinder 65 through piping as shown in FIG. Be done. The valves in the power steering valve set 64 are controlled based on the operation of the steering handle 107, whereby supply / discharge control of the hydraulic oil introduced to the power steering valve set 64 from the inlet port 64a to the power steering cylinder 65 is performed. To be 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 the pressure oil pipe 66, the line filter 67, and the pressure oil pipe 68 are used. As shown in FIG. 8, it is supplied to the inlet port 70 a of the travel valve set 70 provided in the transmission 1.

  In the travel valve set 70, as shown in FIG. 3, 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 speed increase drive clutch 32H of the drive mode switching clutch 32, for automatic braking A group of valves for supplying and discharging hydraulic oil to hydraulic cylinders 76L and 76R is incorporated. The respective valves included in the hydraulic fluid supply and discharge control valve group will be described.

  A reverser clutch directional control valve 71 is provided to control the hydraulic oil supply and discharge to the forward clutches 13F and 13R of the reverser clutch 13. The directional control valve 71 supplies oil to the forward clutch 13F and discharges oil from the reverse clutch 13R, neutral position discharges oil from the forward clutch 13F and reverse clutch 13R, and discharges oil from the forward clutch 13F. It can be switched to three positions of the reverse drive position for supplying oil to the reverse clutch 13R. The directional control valve 71 is a hydraulic pilot valve, and the forward switching valve 72F for applying a pilot pressure for setting the directional control valve 71 in the forward position, and the directional control valve 74 in 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. Further, regardless of the position of the directional control valve 71, the clutch valve 112 is used to discharge oil from the forward clutch 13F and the reverse clutch 13R by pressing on the clutch pedal 112 to separate the two clutches 13F and 13R. Is provided.

  A front wheel normal speed drive switching valve 74L is provided for hydraulic fluid supply and discharge to the front wheel normal speed drive clutch 32L of the drive mode switching clutch 32, and front wheel acceleration drive is provided for hydraulic oil supply and discharge to the front wheel acceleration drive clutch 32H. A switching valve 74H is provided. The switching valves 74L and 74H are electromagnetic switching valves controlled by the controller based on the operation of the drive mode operation tool. Also, a left automatic brake switching valve 75L is provided for supplying and discharging hydraulic oil to the 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 the automatic brake hydraulic cylinder 76R for operating the 17R. The switching valves 75L and 75R are electromagnetic switching valves controlled by the controller based on the turning operation of the steering handle 107 when the automatic brake setting operation tool is set to the automatic brake setting.

  The relief valve 69 is incorporated in the travel valve set 70 provided with the above-described hydraulic oil supply / discharge control valve group, and the relief oil of the relief valve 69 is the charge valve mechanism in the HMT that is the main transmission 12 It is used for replenishment of the hydraulic fluid of the closed circuit between hydraulic pump 12P and hydraulic motor 12M via 12d or 12e. A portion of the oil from the inlet port 70a which does not flow through the relief valve 69 is diverted from the travel valve set 70 to the HMT as the main transmission 12, and the pump swash plate 12b of the HMT is controlled. Are supplied to the direction control valve 17e and the hydraulic cylinder 17f constituting the servo mechanism of the above, and the rest are 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 and discharge control valve group of the travel 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 through the incorporated valve.

  The discharge oil of the second hydraulic pump 62b is supplied via the 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 valve set 87 for working oil pressure control for working machine oil pressure having an external outlet port for oil pressure control (float control etc.) of the working machine, and a valve set for supplying and discharging hydraulic oil to the attitude control cylinder 89 And 88 and a valve set 90 for supplying and discharging hydraulic oil to the lift cylinder 91. Although one lift cylinder 91 is shown in FIG. 3, in actuality, a pair of left and right lift cylinders 91 are provided in the transmission 1 as shown in FIG. 4, FIG. 5, FIG. 7, FIG. It is interposed between the bosses 7c of the pair of left and right lift arms 7 and the pair of lower links 115b. The posture control cylinder 89 is interposed between the bracket 7b at the end of either the left or right lift arm 7 and the lower link 115b on that side, and the bracket 7b on the other left or right lift arm and its side A link rod is interposed between the lower link 115b and the lower link 115b.

  Further, as shown in FIG. 3 to FIG. 7, oil is supplied from the oil passage block 83 of the transmission 1 to the oil cooler 85 disposed at the front of the tractor 100 via the oil pipe 84. The cooled oil is returned to the pipe joining member 78 provided in the transmission 1 via 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 later, the lubricating oil pipe 79 and The left and right lubricating oil pipes 81 (left and right lubricating oil pipes 81L and 81R) are connected via the pipe branch member 80, and the left and right axles 28L and 28R in the transmission 1 are connected via the left and right lubricating oil pipes 81L and 81R. Lubricating oil is supplied to the tapered roller bearings 46 and 47 for supporting each of them.

  Next, an arrangement configuration of each mechanism, members, etc. in the transmission 1 will be described with reference to FIGS. 4 to 12, 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 FIG. 4 to FIG. 8 etc., the casing of 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, 5R), and a pair of left and right axle cases 6. It combines (6L and 6R).

  A block constituting the travel valve set 70 is fixedly provided on one left and right outer side surfaces (right side surface in the present embodiment) of the front half portion (facing the front room 2F described later) of the transmission case 2. Also, the oil passage block 83 and the hydraulic control valve set 87 for work machine control 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 There is. The base end of each lift arm 7 is pivotally supported by the transmission case 2 via a horizontally extending pivot shaft 7a, whereby the pair of left and right lift arms 7 can be pivoted in the longitudinal direction. It is assumed that the case 2 is supported.

  A bracket 7 b is formed at the tip of each lift arm 7, and as described above, one bracket 7 b of the left and right lift arms 7 is connected to the lower link 115 of that side. 3 is connected to the posture control cylinder 89 illustrated in FIG. 3, and the bracket 7 b of the other left and right lift arms 7 is not illustrated so as to connect the other lift arm 7 to the lower link 115 on that side. The rods are connected. Further, a boss 7c is provided in the middle of each lift arm 7 between the base end and the tip, and each boss 7c of each of the left and right lift arms 7 has each lift arm 7 as described above. The lift cylinder 91 illustrated in FIG. 3 is connected to connect the lower link 115 to the left and right lower links 115.

  At the front end of the transmission case 2, an HMT case 3 for accommodating an HMT (not shown in FIGS. 4 to 12) as the main transmission 12 is fixed in a forwardly extending manner. The HMT case 3 supports an input shaft 21 extending in the front-rear direction, as shown in FIG. The input shaft 21 projects forward from the HMT case 3 so as to be connected to the output shaft of the engine 10 via the universal joint-equipped transmission shaft 11 as described above.

  The interior of the transmission case 2 is divided into a front chamber 2F and a rear chamber 2R by vertical partition walls 2a extending in the left-right direction, as seen in FIGS. In the front chamber 2F, a reverser clutch 13 and an auxiliary transmission 14 which are not shown here are accommodated. The auxiliary transmission output shaft 25 of the auxiliary transmission 14 extends in the front-rear direction, and the rear portion thereof is supported by the partition wall 2 a via a bearing 39. Further, the rear end portion of the auxiliary transmission output shaft 25 is plunged into the rear chamber 2R through 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 as shown in FIG. 9 and the like, a bevel pinion 25d provided at the rear end of the auxiliary transmission output shaft 25 meshes with the bevel ring gear 15a of the rear differential mechanism 15. ing.

  As shown in FIGS. 9 to 11, left and right openings 2d and 2e are provided on the left and right outer walls of the transmission case 2 so as to define the left and right ends of the rear chamber 2R. The inner end (end on the transmission case 2 side) 5a of each of the left and right differential output shaft cases 5 is an open end and is bulged like a flange. The inner end portions 5 a of the left and right differential output shaft cases 5 are joined to the left and right outer walls of the transmission case 2 so as to close the openings 2 d and 2 e of the transmission case 2. The brakes 17 are fitted in the inner end 5 a of each differential output shaft case 5 and are disposed along the left and right openings 2 d and 2 e of the transmission case 2. That is, the inner end 5a which is the right end of the left differential output shaft case 5L is joined to the left outer wall around the left opening 2d of the transmission case 2 so that the left brake 17L is attached to the left opening 2d of the transmission case 2 The right brake 17R is attached to the right outer wall around the right opening 2e of the transmission case 2 by joining the inner end 5a which is the left end of the right differential output shaft case 5R. It is installed along the right opening 2e of.

  As can be seen in FIG. 10, a brake camshaft 17b extending in the left-right direction is pivotally supported by the front end of the inner end 5a of each differential output shaft case 5. A cam is formed at the inner end of the brake camshaft 17 b and is linked with the pressing member of each brake 17 in the differential output shaft case 5. The outer end portion of the brake camshaft 17 projects to the outer side of the differential output shaft case 5, and a brake arm 17a is fixed to the projecting outer end. Thus, the brake arm 17a is supported on the left and right sides of the transmission 1 in front of the left and right differential output shaft cases 5L and 5R so that the brake arms 17a can be used as the left and right brake pedals. Also, they are linked to the aforementioned automatic brake hydraulic cylinders 76L and 76R.

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

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

  As shown in FIGS. 10 and 11, the bevel ring gear 15a of the rear differential mechanism 15 is disposed adjacent to the left side of the support member 15e, and the right bearing 41R fitted in the center hole of the support member 15e is A central boss portion 15a1 formed in the bevel ring gear 15a is inserted in an extended manner. 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 is engaged 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 15b1 is formed at the left end of the differential case 15b so as to extend leftward from the main body of the differential case 15b, and the boss 15b1 is fitted into the left bearing 41L in the partition 15b. .

  The right differential output shaft 26R is supported by the right differential output shaft case 5R so as to extend 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, the right brake 17R is disposed adjacent to the right side of the support member 15e fitted in the right opening 2e. The inner end (left end) of the right differential output shaft 26R extends further inward (left) than the right brake 17R and is inserted through the central boss 15a1 of the bevel ring gear 15a in the right bearing 41R. The front end portion is disposed in the right portion of the main body of the differential case 15b. A right bevel differential gear 26b is fixed at an inner end (left end) of the right differential output shaft 26R.

  The left differential output shaft 26L is supported by the left differential output shaft case 5L so as to extend in the left-right direction. The left brake 17L is provided around the left differential output shaft 26L, and 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 as described above, the left brake 17L is disposed adjacent to the left side of the left opening 2d. The inner end (right end) of the left differential output shaft 26L extends further inward (right) than the left brake 17L, and is inserted into the boss 15b1 of the differential case 15b in the left bearing 41R. A portion is disposed within the left portion of the main body of the differential case 15b. A left bevel differential gear 26a is fixed to an 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 includes left and right bevel differential side gears 26a and 26b. I am engaged. In this embodiment, the differential pinion shaft 15d is formed in a cross shape, and the four bevel differential pinions 15c are arranged at equal intervals on the vertical surface in the front-rear direction, and each bevel differential pinion 15c is a left and right bevel differential gear 26a and 26b are engaged, but the arrangement and the number of bevel differential pinions 15c are not limited.

  The slide ring 16a of the differential lock mechanism 16 is mounted on the boss 15b1 of the differential case 15b so as to be slidable in the left-right direction along the boss 15b1 between the support wall 2b and the main body of the differential case 15b. The differential lock pin 16b extends rightward from the slide ring 16a, and is fitted into the main body of the differential case 15b through a hole formed at the left end of the main body of the differential case 15b. The differential lock pin 16b slides integrally with the slide ring 16a, and 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 which is 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 to extend in the left-right direction at the upper part of the rear chamber 2R, and a fork 40a extended from the fork shaft 40 is fitted in the 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. 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 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 accessible to the rear differential mechanism 15 disposed in the right portion of the rear chamber 2R.

  As shown in FIGS. 9 and 10, the rear cover 4 is joined to the rear end of the transmission case 2 so as to close the rear end opening 2g of the transmission case 2. A rear PTO shaft 60 extending in the front-rear direction is supported by the rear cover 4 via a bearing 60 c 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 working machine connected to the tractor 100 via the working machine mounting link mechanism 115 via a transmission shaft with a universal joint etc. The rear end of the rear PTO shaft 60 is connected.

  A gear 60a as shown in FIG. 2 is provided on the rear PTO shaft 60 in a portion behind the support wall 2c of the rear chamber 2R of the transmission case 2 or in the rear cover 4 and the rear PTO shaft 60 and the gear Although the PTO transmission shaft 59 etc. interlocked and linked via 59a * 60a are arrange | positioned, FIG. 9 thru | or 11 abbreviate | omits these in figure.

  The axial center height of the rear PTO shaft 60 supported by the transmission 1 in this way is substantially the same as the axial center height of the differential output shaft 26 (26L, 26R) as shown in FIG. 9 and 10, the tractor 100 is disposed immediately on the left side of the rear differential mechanism 15, at a position overlapping the left differential output shaft 26L, and in a state where the transmission 1 is provided to the tractor 100. It will be arranged in the approximate center of the left and right.

  On the left and right sides of the rear PTO shaft 60, lift cylinders 91 and lower links 115b on the left and right sides of the work machine mounting link mechanism 115 described above are disposed. The rear end portions of the left and right differential output shaft cases 5 (5L and 5R) to be extended are disposed close to each other. Here, temporarily, a reduction gear mechanism interposed between the differential output shaft 26 and the axle shaft 28 is disposed in a portion near the inner end portion of the differential output shaft case 5 in the vicinity of the brake 17. Further, if the reduction gear mechanism is a planetary gear mechanism interposed between the differential output shaft 26 and the axle 28 disposed on the same axis, the reduction gear mechanism 5 in the differential output shaft case 5 The housing portion of the gear mechanism bulges rearward, which may cause interference with the above-described members in the work implement mounting link mechanism 115 disposed immediately after that.

  However, as will become apparent from the description of the transmission configuration from the differential output shaft 26 to the axle 28 below, in this embodiment, the first and second reduction gear mechanisms 18 and 19 are located near the hub 28a of the axle 28. Since the differential output shaft case 5 is accommodated in the portion near the outer end portion of the differential output shaft case 5 and in the axle case 6 outside the differential output shaft case 5, it is disposed immediately before the lift cylinder 91 or the lower link 115b in the work machine mounting link The portion near the inner end of the differential output shaft case 5 does not accommodate such a reduction gear mechanism and is a portion that accommodates only the differential output shaft 26 with a relatively small diameter, Swelling to the rear is also suppressed. Furthermore, although a planetary gear mechanism is used as the second reduction gear mechanism 19 housed in the outer end portion of the differential output shaft case 5, between the differential output shaft 26 and the second reduction gear mechanism 19 The first reduction gear mechanism 18 consisting of a spur gear train is configured to be interposed, and this has an effect of arranging the second reduction gear mechanism 19 and the axle shaft 28 forward, and the differential output shaft case 5 Not only the portion close to the inner end but also the portion close to the outer end thereof and further the axle case 6 disposed on the outer side can suppress the rearward expansion. Because of this, interference with the work implement mounting link mechanism 115 at the rear of the differential output shaft case 5 and the axle case 6 is avoided.

  The transmission mechanism consisting of the differential output shaft 26, the reduction shaft 27, the axle 28, and the first and second gear mechanisms 18 and 19 in the left and right sides of the transmission 1 is constructed symmetrically. Although only the transmission mechanism from the right differential output shaft 26R to the right axle 28 at the right side of the transmission 1 is shown in FIGS. Hereinafter, based on these drawings, the support structure of the transmission mechanism of each of the left and right sides of the transmission 1 will be described.

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

  As shown in FIGS. 9 to 11, a bearing wall 5 c is formed inside the portion near each outer end 5 b of each differential output shaft case 5. 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 the outer end 5b of the differential output shaft case 5 is joined by joining them. A continuous opening is formed in the inner end 6b of the axle case 6, and the outer peripheral edge of the internal gear 19b of the planetary gear mechanism as the second reduction gear mechanism 19 is fitted to this opening. . The support member 49 and the internal gear 19b are fastened together to the axle case 6 by 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 5c, and a ball bearing 43 is fitted in the support member 49. The differential output shaft 26 is inserted into the ball bearing 42 in the bearing wall 5 c, and the outer end thereof is axially supported by the 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. Although the flat gear 18a is formed on the differential output shaft 26 in the present embodiment, the flat gear 18a is a member different from the differential output shaft 26, and the differential output shaft 26 is formed by spline fitting or the like. It may be fixed on the outer peripheral surface. Thus, the outer end of the differential output shaft 26 and the spur gear 18a provided thereon are supported by the bearing wall 5c of the differential output shaft case 5 and the support member 49 via the left and right ball bearings 42 and 43. ing.

  The portion of the differential output shaft case 5 from the bearing wall 5c to the outer end 5b in the left-right direction is bulged forward of the portion supporting the differential output shaft 26, and 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. The ball bearing 44 is fitted in a portion of the bearing wall 5c that protrudes forward relative to the ball bearing 42. On the other hand, in the portion of the support member 49 that protrudes forward than the ball bearing 43, A ball bearing 45 is fitted.

  A flat gear 18b having a diameter larger than that of the flat gear 18a is disposed in front of the flat gear 18a between the bearing wall 5b and the support member 49, and a central boss of the flat gear 18b extends to both left and right sides. It is inserted into the left and right bearings 44, 45. The flat gear 18a and the flat gear 18b are in direct mesh with each other. A decelerating shaft 27 having an axial center in the left-right direction is inserted into the support member 49, and the decelerating shaft 27 is disposed in parallel to the differential output shaft 26 in front of the differential output shaft 26. There is. The inner side (closer to the transmission case 2) of the reduction shaft 27 is inserted into the boss hole of the flat gear 18b as a gear shaft, and is fixed to the flat gear 18b by spline fitting. Thus, the inner end of the reduction shaft 27 and the spur gear 18b provided thereon are supported by the bearing wall 5c of the differential output shaft case 5 and the support member 49 via the left and right ball bearings 44 and 45. .

  As described above, by meshing the flat gear 18 a provided on the outer end of the differential output shaft 26 with the flat gear 18 b provided on the inner end of the reduction shaft 27, the differential output shaft 26 is 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 portion of the first differential output shaft case 5 near the outer end 5b, and in the left-right direction, the left and right outer portions of the transmission case 2 and the hub of the axle 28 It is disposed at an intermediate position between 28a and 28a. This position is where the lower link 115b of the work machine mounting link mechanism 115 as described above, the lift cylinder 91, etc. are in proximity to the rear thereof, but as described above, the reduction shaft 27 is in front of the differential output shaft 26. The portion of the differential output shaft case 5 which is disposed and which accommodates the first reduction gear mechanism 18 is also formed to bulge forward from the portion supported by the differential output shaft 26, so that the differential output shaft This portion of the case 5 does not bulge backward for housing the first reduction gear mechanism 18, whereby interference between the differential output shaft case 5 and these members for mounting the work machine is prevented. It is supposed to be avoided.

  The outer side (closer to the axle) of the reduction shaft 27 projects outward from the support member 49, and the outer end 5b of the differential output shaft case 5 and the inner end 6b of the axle case 6 as described above. And are disposed in openings formed in the inside thereof, and a sun gear 19a is formed on the outer portion of the reduction shaft 27. In the 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 horizontally extending pivot shaft 19e parallel to the differential output shaft 26 and the reduction shaft 27. Preferably, a plurality of planet gears 19c are provided on one carrier 19d. The planet 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, a planetary gear mechanism as the second reduction gear mechanism 19 is configured with the outer portion of the reduction shaft 27 as a sun gear shaft.

  A boss 6 d is formed at the outer end of the axle case 6, and left and right inner and outer tapered roller bearings 46 and 47 are fitted in the boss 6 d. On the other hand, a boss 19d1 is formed at the outer end of the carrier 19d, extends outward, and is fitted into the left and right inner tapered roller bearings 46. 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 bearings 47. . The axle 28 is inserted through the oil seal ring 48 thus fitted in the oil seal cover 6a and the tapered roller bearings 46 and 47 fitted in the boss 6d of the axle case 6, and the inner end thereof is The boss 19d1 of the carrier 19d is fitted by spline fitting.

  In this manner, the axles 28 fixed to the carrier 19 d are disposed coaxially with the reduction shaft 27 on the left and right outside of the reduction shaft 27 as the sun gear shaft of the second reduction gear mechanism 19. The outer end of the reduction shaft 27 and the inner end of the axle 28 are in close proximity, and a shim 29 as a thrust bearing is interposed in the gap between them, and the 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 its sun gear shaft. However, as described above, since the reduction shaft 27 is disposed in front of the differential output shaft 26, the second reduction gear mechanism 19 is also eccentrically disposed in front of the differential output shaft 26. Therefore, the outer end 5b of the differential output shaft case 5 accommodating the second reduction gear mechanism 19 is formed to project forward than the portion supporting the differential output shaft 26, and the outer end The axle case 6 in which the inner end 6b is joined to the end 5b also supports the axle 28, which is disposed on the same axial center with respect to the reduction shaft 27, so the axial center position of the differential output shaft 26 If it sees from the front, it will be deflected and arranged. Therefore, the rear end of the outer end 5 b of the differential output shaft case 5 accommodating the second reduction gear mechanism 19 and the entire axle case 6 also bulges rearward when viewed from the axial center position of the differential output shaft 26. Interference with the lower link 115b for installation of the working machine, the lift cylinder 91, and the like which is not released and may approach behind at 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, in particular, a tractor 100 to which the transmission 1 is applied. The point that it is considered that it is a thing of middle class is explained.

  Regarding the reduction gear mechanism, a planetary gear mechanism is used as the second reduction gear mechanism 19 that supports the axle 28 in consideration of the support strength required for the axle 28 as the axle shaft of the tractor 100 of the middle class. Then, since the axial center length of the axle 28 is short, the second reduction gear mechanism 19 is partially accommodated in the axle case 6 and in a position very close to the hub 28 a in the left-right direction, that is, away from the transmission case 2 Placed in the

  Although the second reduction gear mechanism 19 as this planetary gear mechanism is not sufficient to secure the required reduction ratio between the differential output shaft 26 and the axle 28 in the middle class tractor 100, Since most of the necessary reduction ratio is secured in the second reduction gear mechanism 19, the reduction ratio to be supplemented by the reduction gear mechanism additionally provided to the second reduction gear mechanism 19 can be small. Moreover, the second reduction gear mechanism 19 which is a planetary gear mechanism supports the axle 28 for which a large support strength is required, and the additional reduction gear mechanism can reduce the differential output shaft 26 which can be reduced in support strength. You should support it. Therefore, in the present embodiment, the first reduction gear mechanism 18, which is the additional reduction gear mechanism, is provided with flat gears 18a and 18b between the parallel differential output shaft 26 and the reduction shaft 27. The flat gear train structure is adopted, and since the reduction ratio can be small, the distance between the differential output shaft 26 and the reduction shaft 27 can be small, and the first reduction gear mechanism 18 can be made compact. And In the case where two such reduction gear mechanisms are provided to secure the reduction ratio, if two planetary gear mechanisms are provided, the cost will increase. However, in the present embodiment, the first reduction By making the gear mechanism 18 into a flat gear train structure, the cost can be reduced, and the middle class tractor 100 can be matched.

  Further, the first reduction gear mechanism 18 of this flat gear train structure has a second reduction gear mechanism for shortening the axial length of the reduction shaft 27 which also serves as the sun gear shaft of the second reduction gear mechanism 19 which is a planetary gear mechanism. The differential output shaft case 5 is accommodated in a portion close to the outer end 5 b so as to be close to 19. Therefore, the differential output shaft 26 is considerably long in the axial direction, and a portion of the differential output shaft case 5 that covers the differential output shaft 26 between the inner end 5 a and the bearing wall 5 c. Also, as the axial center length of the differential output shaft 26 is longer, it is longer in the left-right direction. Since this portion only needs to cover the differential output shaft 26, the radial size of the differential output shaft 26 is narrowed, and the configuration is compact and simple, and the differential output shaft case 5 itself is manufactured. The cost can also be reduced.

  In this way, by ensuring the axial length of the differential output shaft 26 to be large, the small portion in the radial direction 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 the interference between the differential output shaft case 5 and a member for mounting a working machine disposed behind the case 5.

  Furthermore, to make the first reduction gear mechanism 18 a flat gear train structure causes interference between the housing portion that accommodates the second reduction gear mechanism 19 that is a planetary gear mechanism and the member for mounting the work machine. It contributes to securing the structure to avoid. The planetary gear mechanism needs to arrange its sun gear shaft and the output shaft fixed to the carrier on the same axis. If such a planetary gear mechanism is configured with the differential output shaft 26 as a sun gear shaft without the reduction shaft 27, the differential output shaft 26 and the axle 28 are disposed on the same axial center, and this planetary gear mechanism The rear end of the housing part that accommodates the fulcrum also bulges backward largely when viewed from the axial center of the differential output shaft 26, and interference with the work implement mounting member should be a problem, but the first deceleration The gear mechanism 18 has, as its output shaft, a reduction shaft 27 disposed in front of the differential output shaft 26, and the second reduction gear mechanism 19 which is a planetary gear mechanism is a sun gear shaft of this reduction shaft 27. Therefore, as described above, the second reduction gear mechanism 19 is also biased forward as viewed from the axial center of the differential output shaft 26, and the outer side of the differential output shaft case 5 that accommodates the second reduction gear mechanism 19. The end 5 b and the rear end of the axle case 6 do not bulge backward, 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. Do. As described above, ball bearings 42, 43, 44, 45 are used as bearings for supporting the spur gears 18a, 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 spur gears 18a and 18b and can receive small stresses due to the engagement between the spur gears 18a and 18b, a large support strength is not required either. The 43, 44 and 45 are also simple and inexpensive like ball bearings.

  On the other hand, the axle 28 is thick in the radial direction and short in axial center length, so it has a cantilevered shape, and the stress received from the rear wheel 8 fixed to the hub 28a is also strong. As described above, the tapered roller bearings 46 and 47 are used because the required strength is required.

  Since the stress applied to the tapered roller bearings 46 and 47 is large, a large amount of lubricating oil is also required. 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 largely separated from the transmission case 2 disposed at the left and right center of the tractor 100 in the left and right direction. Therefore, with the inclination of the tractor 100 in the left and right direction, the axle case 6 in which the tapered roller bearings 46 and 47 are disposed moves largely up and down, and from the tapered roller bearings 46 and 47 with the upward movement. There is a high possibility that the lubricating oil will escape. Therefore, a positive lubricating oil supply structure for the tapered roller bearings 46 and 47 is desired.

  Therefore, in the present embodiment, as seen in FIG. 12 and the like, in the space in the boss portion 6d of the axle case 6, the distance between the left and right tapered roller bearings 46 and 47 is taken in the left-right direction. A clearance space as lubricating oil reservoir 6e is secured between 47. As described above, in the transmission 1, left and right lubricating oil pipes 81 (81 L and 81 R) branched from the pipe branch member 80 are extended, and the end of each lubricating oil pipe 81 is provided at the upper end of each axle case 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 discharge oil of 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. Furthermore, as described above, the pipe branch member 80 is supplied with oil from the pipe joining member 78 via the lubricating oil pipe 79, and the pipe joining member 78 is an oil cooler via the oil pipe 86. Since the lubricating oil to the PTO clutch 53 and the lubricating oil to the reverser clutch 13 also join the flow of oil from 85, a sufficient amount of lubricating oil is supplied to the lubricating oil pipes 81L and 81R. Thus, regardless of the swing 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 also be supplied to the second reduction gear mechanism 19 or the like which is a planetary gear mechanism. This may be supplied through the lubricating oil reservoir 6e or the tapered roller bearings 46 and 47, or by forming an oil path from the lubricating oil port 6c to the second reduction gear mechanism 19 in the axle case 6 for lubrication An oil may be supplied.

  Next, the structure of the vehicle body frame 101 and the connection structure of the engine 10, the front axle drive device 20, and the transmission case 2 of the transmission to the vehicle body frame 101 will be described with reference to FIGS. The vehicle body frame 101 has a left side frame 120L and a right side frame 120R extended in the front-rear direction of the tractor 100, and each of the left side frame 120L and the right side frame 120R is a vertical flat front side frame member 121 and a vertical flat plate. The rear side frame member 122 is formed by connecting the rear end portion of the front side frame member 121 and the front end portion of the rear side frame member 122.

  The connection between the front side frame member 121 and the rear side frame member 122 will be described in detail. The rear end joint portion 121a of the front side frame member 121 and the front end joint portion 122a of the rear side frame member 122 overlap in a side view. Spacers 123 are disposed between the rear end joint portion 121 a of the front side frame member 121 and the front end joint portion 122 a of the rear side frame member 122. The front frame member is fastened by fastening the rear end joint portion 121a of the front side frame member 121, the front seat plate member 123, and the front end joint portion 122a of the rear side frame member 122 stacked in this manner with the bolt 141 inserted in the left and right direction. The rear side frame members 122 are integrally formed, and are configured as the side frames 120L and 120R.

  Furthermore, a vertical flat plate-like front end frame member 124 is extended in the left-right direction of the tractor 100, and the left end portion of the front end frame member 124 is fastened to the front end of the front side frame member 121 of the left side frame 120L with a bolt 142. The front ends of the left frame 120L and the right frame 120R are connected by the front end frame member 124 by fastening the right end portion of the member 124 to the front end of the front side frame member 121 of the right side frame 120R with a bolt 142. Thus, the vehicle body frame 101 is configured in a U-shape in plan view by the left side frame 120L, the right side frame 120R, and the front end frame member 124.

  The bonnet 102 constituting the front of the vehicle of the tractor 100 is mounted on the left and right front side frame members 121, 121 of the vehicle body frame 101, and the front end frame member 124 is a front formed at the front end of the bonnet 102. It is placed directly below the grille.

  At the rear of the front end frame member 124, a front axle support frame member 125 for supporting the front axle drive device 20 disposed below the vehicle body frame 101 is bridged between the left and right front side frame members 121 and 121. There is. The front axle support frame member 125 is formed in a horizontal plate shape so as to cover the upper side of the left and right center of the front axle drive device 20 disposed below the front axle support frame member 125, and the left and right end portions are formed in a vertical plate shape The vertical plate-shaped left and right end portions are fastened to the left and right front side frame members 121 by bolts 143 in the left-right direction. A plurality of bolt bosses 125a extend downward from the horizontal plate-like portion of the front axle support frame member 125, and a bolt stopper formed on the case of the front axle drive 20 is fitted to the lower end of the bolt boss 125a. And fixing the case of the front axle drive unit 20 to the front axle support frame member 125 by bolting the case to the bolt boss 125a, thus supporting the front axle drive unit 20 by the vehicle body frame 101. And

  A protective plate 126 is disposed immediately behind the front axle support frame 125, and the left and right end portions thereof are fastened to the left and right front side frames 121 and 121 with bolts 144, thereby the left and right front frame A protective plate 126 is bridged between 121 and 121. The protective plate 126 is a plate that inclines substantially forward and upward, and is disposed below a fan belt or the like disposed at the front end of the engine 10. Behind the protective plate 126, a space S1 is provided between the left and right front side frame members 121 and 121 up to the rear end portion 121a. In this space S1, the lower portion of the engine 10 (oil pan, crank case, etc.) Is supposed to be placed.

  When the engine 10 is mounted on the vehicle body frame 101, the engine support stays 150 are fixed to the left and right outer side surfaces of the left and right front side frame members 121 at positions above the protective plate 126. The left and right engine support stays 150 are provided with anti-vibration rubber, and the engine 10 is supported on the vehicle body frame 101 via the anti-vibration rubber.

  As described above, the rear end joint portion 121a of each front side frame member 121 is joined to the front end joint portion 122a of each rear side frame member 122 by fastening with the bolt 141, and the rear side of the left and right front side frame members 121 and 121 The rear end of the end joint 121a roughly defines the rear end of the space S1 for disposing the lower portion of the engine 10 as described above. A bridge-like frame member 127 is bridged between the right and left rear side frame members 122 and 122 immediately behind the rear end of the rear end joint portion 121a of the left and right front side frame members 121 and 121, that is, immediately after the space S1. It is done. The left and right end portions of the bridge-like frame member 127 are formed in a wide flange shape in the upper and lower back and forth, and the left and right end portions of these flanges are fastened to the left and right rear frame members 122 with bolts 145 in the left and right direction. . The portion extending between the left and right ends and extending in the left-right direction includes the lower rear end portion of the engine 10 to be disposed immediately before that, the steering hydraulic valve set 64 to be disposed immediately thereafter, and the like. In order to secure the arrangement space of hydraulic equipment and piping etc., it becomes thinner vertically and horizontally compared with the left and right end of the flange shape, but it has a certain width in the front and back direction and its cross sectional shape The support strength is secured by forming an elliptical shape having a major axis (see FIG. 21).

  The cabin support stay 128 is projected to the left and right from the respective rear side frame members 122 directly above the joint portions of the left and right rear side frame members 122 with the rear portions of the flange-like left and right ends of the bridge-like frame members 125 It is set up. The left and right front end portions of the bottom portion of the cabin 103 are mounted on the cabin support stay 128, and fixing pins protruding upward from the horizontal plate surface 128a are inserted into the bottom portion of the cabin 103, whereby the front and rear center of the vehicle body of the tractor 100 is achieved. It supports the front of the cabin 103 which is a part.

  A space S2 is secured between the left rear side frame member 122 and the right rear side frame member 122 at the rear of the bridge-like frame member 127. The second half of the space S2 is a space for arranging the front portion of the transmission case 2 of the transmission 1. The first half of the space S2 is between the engine 10 and the input shaft 2 of the transmission 1 Of hydraulic equipment such as the transmission shaft 11 interposed, the pump set 62 disposed forward of the transmission case 2, the hydraulic valve set 64 for power steering, the line filter 67, and pressure oil pipes 63 and 66 connected thereto. It is considered as a placement space.

  In the rear half of the space S2 between the left and right rear frame members 122, 122, the front part of the transmission case 2 constituting the front chamber 2F is disposed. The rear ends of the frame members 122 are connected by bolt fastening. The rear half of the transmission case 2 thus supported by the vehicle body frame 101 extends rearward from the rear end of the vehicle body frame 101, and the rear differential of the left and right differential output shafts behind the rear ends of the left and right rear frame members 122. Left and right open end portions 2d and 2e which are attachment end portions of the cases 5L and 5R are disposed.

The fastening structure of the left and right rear side frame members 122 to the transmission case 2 will be described in detail. As can be seen with reference to FIG. 23, boss holes 122b are formed in the upper and lower portions of the rear end portion of the rear side frame member 122, respectively, and each cylindrical boss hole 122b has a pin hole 135a in the left-right direction. The boss member 135 is inserted. The left and right (axial center) inward end portions of each boss member 135 project leftward and rightward from the inner side surface of each rear frame member 122 (that is, into the space S2 between the left and right rear frame members 122 and 122) The left and right inner ends of the transmission case 2 abut on the left and right outer surfaces of the transmission case 2 disposed between the left and right rear frame members 122. A cylindrical fastening pin 132 having a bolt hole 132a coaxial with the pin hole 135a is inserted through the pin hole 135a. The fastening pins 132 project leftward and rightward from the boss member 132 and are fitted into cylindrical recesses 2 h formed on the left and right sides of the transmission case 2. A bolt 134 having an axial center in the left-right direction is inserted into the bolt hole 132a of the fastening pin 132, and a screw ridge portion formed at the left and right inner end is further inside the left and right inner ends of the fastening pin 132 in the recess 2h. It projects toward the side and is screwed into a female screw hole formed in the transmission case 2.

Thus, the fastening pins 132 inserted through the boss members 135 provided on the upper and lower end portions of the rear end portions of the left and right rear side frame members 122 are inserted into the concave portions 2h formed on the upper and lower sides of the left and right side portions of the transmission case 2 Further, the transmission case 2 is fastened to the left side frame 120L and the right side frame 120R of the vehicle body frame 101 by screwing the pair of upper and lower bolts 134 inserted through the fastening pins 132 into the back of each recess 2h of the transmission case 2 It has stopped.

  On the other hand, flanges 136 are formed on the left and right (axial center) direction outer ends of each boss member 135, and the flanges 136 are in contact with the outer surface of each rear side frame member 122. It is fixed by welding to the outer surface of the rear side frame member 122. In addition, W of FIG. 23 shows the weld bead given for this welding. The left and right outer ends of the fastening pin 132 inserted into the pin hole 135 a of the boss member 135 are covered with a disc-like spacer plate 133 added to the outer surface of the flange 136. The head end of the bolt 134 inserted into the bolt hole 132a of the fastening pin 132 is disposed on the left and right outside of the spacer plate 133, and the head of the bolt 134 is screwed into the transmission case 2 as described above. The part clamps the spacer plate 133 to the outer surface of the flange 136, thereby preventing the fastening pin 132 from coming out of the boss member 135 to the left and right.

  The outer peripheral edge of the flange 136 of each boss member 135 is seen in the axial direction (left and right direction) of the pin hole 135a which is the insertion direction of the fastening pin 132 and the bolt 134 described later (hereinafter referred to as "side view" It has become non-circular (oval). That is, as shown in FIG. 22, in the side view, the outer peripheral edge of the flange 136 is a bolt hole 122b, a cylindrical portion of the boss member 135 inserted through the bolt hole 122b, and a fastening pin 132 inserted through the pin hole 135a. The pin hole 135a, the fastening pin 132, and the axial center of the bolt 134 (hereinafter referred to as an axial center X) are formed concentrically to surround the bolt 134 inserted into the fastening pin 132. It has an arc-shaped portion 136a whose radius of curvature is R1 and an extending portion 136b extended in a radial direction centering on the axis X with a diameter R2 longer than the radius of curvature R1 of the arc-shaped portion 136a. It has a shape.

  Furthermore, in the present embodiment, the tip end portion of the extension portion 136b opposite to the arc-shaped portion 136a is another arc-shaped portion 136c having a smaller diameter than the arc-shaped portion 136a, and the flange in a side view The overall shape of the outer peripheral edge 136 is egg-shaped. That is, the length R2 defining the length of the extended portion 136b is the length L of a line connecting the axis X, which is the center of curvature of the arc-shaped portion 136a, and the center of curvature Y of the arc-shaped portion 136c. The length is the sum of the radius of curvature R3 from the center of curvature of the arcuate portion 136c, and the radius of curvature R3 of the arcuate portion 136c is shorter than the radius of curvature R1 of the arcuate portion 136a. The width 136 b is formed so as to be gradually narrowed from the arc-shaped portion 136 a toward the arc-shaped portion 136 c.

  Regardless of the shape of the outer peripheral edge of the flange 136 in a side view, for example, the radius of curvature R3 of the arc-shaped portion 136c is the same as the radius of curvature R1 of the arc-shaped portion 136a. The shape of the outer peripheral edge may be oval or elliptical.

  In each rear side frame member 122, a pair of boss members 135 are provided up and down, and the fastening pins 132 and bolts 134 inserted through these boss members 135 are used for upper and lower end portions of the left and right side portions of the transmission case 2 The transmission case 2 having an upper and lower width substantially equal to the upper and lower width of the rear end of the rear side frame member 122 is supported by the upper end and the lower end. Support strength of Mission Case 2 in Japan.

  Then, the extension direction of the extension portion 136b of the outer peripheral edge of the flange 136 is set in consideration of the concentrated portion of the winding stress applied to each of the fastening pins 132 and the boss member 135. That is, conventionally, the outer peripheral edge of the flange provided in such a boss member has a radius of curvature R1 of the arc-shaped portion 136a in the present embodiment concentrically surrounding the axial center X in a side view. As shown in FIG. 22, the boss member 135 has a portion Z where the rolling stress is concentrated. FIG. 22 shows the flange 136 of the upper boss member 135 of the pair of upper and lower boss members 135, and the stress concentration point Z is the lower front portion of the cylindrical portion of the boss member 135. Although not shown, in the lower boss member 135, the stress concentration point Z is the front upper portion of the cylindrical portion of the boss member 135.

  The extended portion 136 b of the outer peripheral edge of the flange 136 is arranged to avoid this stress concentration point Z. That is, for example, in the case of the outer peripheral edge of the egg-shaped flange 136 as in the present embodiment, the pair of extending portions 136b are up and down so as to connect the large diameter arc shaped portion 136a and the small diameter arc shaped portion 136b. It is stretched, and a stress concentration point Z is present between the two stretched portions 136b and 136b. In this manner, the extended portions 136b and 136b of the outer peripheral edge of the flange 136 are disposed to avoid the stress concentration point Z, thereby avoiding stress concentration on the outer peripheral edge which is a welded portion of the flange 136. The structure is such that the weld is less likely to come off.

  Then, as described above, among the upper and lower boss members 135 of each rear frame member 122, stress concentrates on the upper lower portion of the upper boss member 135, and the lower boss member 135 on the upper upper portion thereof. Since the stress concentrates, the extended portion 136b of the outer peripheral edge of the flange 136 of the upper boss member 135 extends in a downwardly inclined manner from the arc-shaped portion 136a so as to bypass such a stress concentration portion, On the other hand, the extended portion 136b of the outer peripheral edge of the flange 136 of the lower boss member 135 extends from the arc-shaped portion 136a in a front upper inclined shape, for example, as shown in FIG. 15 (a) or 16 (a). As can be seen, the outer peripheral shape of the flange 136 in a side view of the pair of upper and lower boss members 135 is axisymmetrical through a horizontal imaginary straight line.

  Furthermore, a pair of upper and lower reinforcing frame members 129 and 130 is provided between the left and right rear side frame members 122 and 122. The upper reinforcing member 129 is provided in front of the pair of upper and lower boss members 135, the fastening pin 132 and the bolt 134 at the rear end of the rear frame members 122, 122 at the upper end thereof. It arranges at the position of approximately the same height, and has fastened the left and right side end parts 129a formed in the flange shape to the left and right rear side frame members 122 with bolts 146. The lower reinforcing member 130 is provided in front of the pair of lower left and right boss members 135, fastening pins 132, and bolts 134 at the rear end portions of both rear side frame members 122, 122, these lower fastening members 135, The flanges 132 and 134 are disposed at substantially the same height, and the left and right end portions 130 a formed in the flange shape are fastened to the left and right rear frame members 122 by bolts 147.

  The flange-like left and right ends of the reinforcing frame members 129 and 130 installed between the two rear side frame members 122 and 122 are respectively disposed near the front of the boss members 135. Since the bolt is tightened, the supporting force of each reinforcing frame member 129 and 130 can be immediately transmitted to each boss member 135 via the rear side frame member 122, and the fastening pin 132 can be firmly supported without bending. is there.

1 Transmission 2 Transmission Case 10 Engine 101 Body Frame 120L Left Frame 120R Right Frame 121 Front Frame Material 121a Rear End Joint 122 (For Front Frame Material) Rear Frame Material 122a Front Frame Joint 124 Front Frame (For Rear Frame Material) 124 Front Frame Material 127 Bridged frame material 129 Reinforcing frame material 129a Left and right end parts 130 (Reinforcing frame material) 130 Reinforcing frame material 130a Left and right end part 132 (Reinforcing frame material) 132 Fastening pin 132a Bolt hole 133 Space board material 134 Bolt 135 Boss member 135a Pin hole 136 flange 136a (large diameter) arc-shaped part 136b extension part 136c (small diameter) arc-shaped part

Claims (3)

A vehicle body frame having a left side frame and a right side frame extending in the longitudinal direction of the tractor,
The left side frame and the right side frame are respectively made of a front side frame member and a rear side frame member, and are configured by connecting a rear end portion of the front side frame member and a front end portion of the rear side frame member.
The engine is supported by the front side frame members of the left side frame and the right side frame,
A pair of upper and lower boss members are fixedly provided at the rear end of the rear side frame member of each of the left side frame and the right side frame, and the rear side frame member is made through the fastening pins inserted into the boss members. The rear end portion is fastened to the mission case,
A pair of upper and lower reinforcing frame members are bridged between the rear side frame member of the left side frame and the rear side frame member of the right side frame,
The left and right ends of the upper reinforcing frame member of the pair of upper and lower reinforcing frame members are portions near the front of the upper boss member in the left and right rear frame members, and The left and right ends of the lower reinforcement frame member are connected to portions of substantially the same height, which are portions near the front of the lower boss member in the left and right rear frame members, the lower boss member When connected substantially to a portion of the same height,
A flange is formed on each of the boss members, and the outer peripheral edge of the flange is fixed by welding to the outer surface of the rear frame member,
The shape of the outer peripheral edge of the flange is an arc-shaped portion concentrically surrounding the fastening pin with a constant radius of curvature centered on the axial center of the fastening pin, and the axial center of the fastening pin It has a shape having a stretched portion which is longer than the radius of curvature of the arc-shaped portion and which is extended so as to project from the arc-shaped portion in the radial direction as the center,
Of the pair of upper and lower boss members, the extended portion of the outer peripheral edge of the flange of the upper boss member extends forward and downward from the axial center of the fastening pin, and the outer peripheral edge of the flange of the lower boss member The extended portion of the vehicle is extended forward and upward from the axial center of the fastening pin . The outer peripheral shape of the flange is an egg shape having an arc-shaped portion having a diameter smaller than that of the arc-shaped portion at a tip end portion of the extended portion opposite to the arc-shaped portion. The body frame of the described tractor. A bridge-like frame material is bridged between the rear side frame material of the left side frame and the rear side frame material of the right side frame, and the bridge-like frame material is the front side frame of the left side frame and the right side frame The vehicle body frame of a tractor according to claim 1 or 2 , which is disposed immediately behind an engine supported by a material .

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