JP4361409B2 - Tractor - Google Patents

Description

  The present invention relates to a tractor.

  Conventionally, as one form of the tractor, a hydraulic case is connected to the upper part of the transmission case, and a lift arm support shaft with an axis line in the left-right direction is passed through the hydraulic case, and the left and right end portions of the lift arm support shaft The lift cylinder is attached to the base end of the pair of left and right lift arms, and is attached to the base end of the working arm in the middle of the lift arm spindle, and is arranged in a horizontal manner in the hydraulic case at the tip of the working arm In other words, the lift arm is moved up and down in conjunction with the expansion / contraction operation of the lifting hydraulic cylinder (see, for example, Patent Document 1).

In addition, a hydraulic circuit is formed in the hydraulic case, and the lubricating oil in the transmission case is used as hydraulic oil and is pumped through the hydraulic circuit to the lift cylinder so as to be extended.
JP 2002-283661 A

  However, in the tractor described above, the lubricating oil in the transmission case is pumped to the lift cylinder as hydraulic oil and the cylinder is operated, so wear pieces that are constantly generated by the meshing of the gear in the transmission case, etc. When the hydraulic filter is clogged with dust, dust may flow into the hydraulic control valve provided in the middle of the hydraulic circuit through the bypass circuit, causing the hydraulic control valve to malfunction.

  For this reason, a structure has been adopted in which a partition plate is interposed between the hydraulic case and the transmission case to separate the hydraulic oil in the hydraulic case and the lubricating oil in the transmission case.

  However, such a separation structure has the following problems.

  (1) When performing performance and function inspections of hydraulic control valves, it is necessary to install the hydraulic case on the transmission case so that hydraulic fluid does not leak. It is difficult by itself, and there is a complexity that a transportation auxiliary device is required.

  (2) There is a need to prevent oil leakage on both sides of the partition plate, and high flatness is required for both sides of the partition plate.

  (3) Since the partition plate is interposed between the hydraulic case and the transmission case, the ground clearance of the hydraulic case is increased by the thickness of the partition plate, and the driver's seat is arranged immediately above the hydraulic case. The degree of freedom in designing the mounting height is reduced.

Therefore, in the present invention, a lift arm is attached to the upper part of the transmission case via a lift arm support, and the lift arm is controlled by a hydraulic control valve via a hydraulic circuit body detachably attached to the lift arm support. The valve cover body is attached to the above hydraulic circuit body, the hydraulic control valve is accommodated in the valve cover body, and the drain of the hydraulic control valve is passed through the drain receiving space formed in the valve cover body. The hydraulic circuit body can be discharged through a drain circuit formed in the hydraulic circuit body, and the hydraulic circuit body is detachably attached to the transmission case via a lift arm support body, and an upper opening box type valve cover body is provided below the hydraulic circuit body. Attach the top edge of the valve in a sealed state and A tractor disposed in a case, wherein the lift arm support is attached to a ring-shaped attachment piece to be attached to a peripheral portion of an opening formed in a ceiling portion of a differential case, and a front portion of the attachment piece And a pair of left and right pivot pieces that rise upward at the rear part of the mounting piece and pivotally support the lift arm spindle. Then, the base end portion of the pair of left and right lift arms is attached to the lift arm support shaft, and a lift cylinder extending and contracting in the vertical direction is interposed between the middle portion of each lift arm and the lower portion of the differential case, The present invention provides a tractor characterized in that a lift arm can be moved up and down by both lift cylinders .

(1) In the first aspect of the present invention, a lift arm is attached to the upper part of the transmission case via a lift arm support, and the lift arm is provided with a hydraulic circuit body that is detachably attached to the lift arm support. The hydraulic control valve can be used to control the hydraulic pressure, the valve cover body is attached to the hydraulic circuit body, the hydraulic control valve is accommodated in the valve cover body, and the drain of the hydraulic control valve is formed in the valve cover body. It is possible to discharge through the drain circuit formed in the hydraulic circuit body through the drain receiving space, and the hydraulic circuit body is detachably attached to the transmission case through the lift arm support, and the top surface is opened at the bottom of the hydraulic circuit body Attach the top edge of the box-shaped valve cover body in a sealed state and place it under the valve cover body. In the transmission case, wherein the lift arm support is attached to a ring-shaped attachment piece that fits to the periphery of the opening formed in the ceiling of the differential case, and the attachment piece A cylindrical hydraulic circuit body support piece that rises upward at the front portion and supports the hydraulic circuit body, and a pair of left and right pivot pieces that rise upward at the rear portion of the mounting piece and pivotally support the lift arm spindle. A pair of left and right lift arms is attached to the lift arm spindle, and lift cylinders that extend in the vertical direction are interposed between the middle part of each lift arm and the lower part of the differential case. Thus, the lift arm can be moved up and down by both lift cylinders .

  Thus, since the valve cover body is attached to the hydraulic circuit body that is detachably attached to the lift arm support body, and the hydraulic control valve is accommodated in the valve cover body, before these are attached to the lift arm support body, In addition, the performance and function of hydraulic control valves can be checked.

  As a result, it is possible to facilitate performance / function inspection, downsizing of the inspection apparatus, and easy handling by human power.

The hydraulic circuit body is detachably attached to the transmission case via the lift arm support, and the upper edge of the upper-opening box-type valve cover body is attached to the lower portion of the hydraulic circuit body in a sealed state. The lower part of the cover body is arranged in the mission case.

  In this way, since the hydraulic circuit body is attached to the transmission case via the lift arm support, the seal on the mounting surface of the lift arm support to the transmission case is used in one place, and the conventional seal method is adopted. can do.

  In addition, since the lower part of the valve cover body is arranged in the transmission case, the ground height of the hydraulic circuit body can be set low, and the installation height of the driver's seat arranged immediately above the hydraulic circuit body can be reduced. A large degree of design freedom can be secured.

  A shown in FIG. 1 is a tractor according to the present invention. The tractor A is provided with a prime mover unit 2 on an airframe frame 1 and a transmission unit 4 is connected to the prime mover unit via a clutch unit 3 in an interlocking manner. A driving unit 5 is disposed on the transmission unit 4, and a PTO transmission unit 6 is detachably linked to a rear portion of the transmission unit 4 so that a front axle case (not shown) is provided below the body frame 1. A pair of left and right front wheels 7 and 7 are interlocked and connected to each other via a transmission, while a pair of left and right rear wheels 9 and 9 are interlocked and connected to the transmission unit 4 via rear axle cases 8 and 8 (see FIG. 12). . 10 is a front guard frame, 11 is a rear guard frame, 12 is a top link for connecting a work machine such as a rotary tiller, 13 is a lower link for connecting a work machine, and 14 is a work machine connecting piece such as a trailer.

  In the following, each configuration of the above-mentioned [motor unit 2], [clutch unit 3], [mission unit 4], [driving unit 5] and [PTO transmission unit 6] will be specifically described in this order. .

[Motor part 2]
As shown in FIG. 1, the prime mover unit 2 includes an engine 15 and the like mounted on the machine body frame 1, and the engine 15 and the like are covered with a hood 16 so as to be freely opened and closed.

[Clutch part 3]
As shown in FIGS. 2 to 4 and 6, the clutch unit 3 rotatably supports an inner / outer double drive shaft 18 extending in the front / rear direction in the clutch housing 17. The heavy drive shaft 18 is formed of an inner drive shaft 19 extending in the front-rear direction and a cylindrical outer drive shaft 20 that is rotatably fitted to the outer periphery of the inner drive shaft 19.

  A base end portion (front end portion) of one inner drive shaft 19 is linked to the engine 15 via a travel clutch 21, and a front end portion (rear end portion) of the inner drive shaft 19 is described later. And the base end portion (front end portion) of the other outer drive shaft 20 is linked to the engine 15 via the PTO clutch 22 and is connected to the outer drive shaft 20. The front end portion (rear end portion) is linked to a PTO transmission mechanism 52 described later.

  Here, a rear end edge portion of the clutch housing 17 is detachably connected to a front end edge portion of a main transmission case 53 of the transmission section 4 to be described later, and the inner and outer double drive shaft bodies 18 are connected to the front end portion. Is pivotally supported by a bearing 24 disposed at the front portion in the clutch housing 17, and a rear end portion is pivotally supported by a bearing 25 disposed at the front portion in the main transmission case 53.

  Moreover, a rear wall 27 having an opening 26 in the center is formed at the inner peripheral edge of the rear end of the clutch housing 17, and a cylindrical support 28 extending in the front-rear direction is formed in the opening 26 in the rear wall 27. It is inserted and attached, and the outer peripheral surface of the middle part of the inner and outer double drive shafts 18 is supported by the cylindrical support 28.

  The cylindrical support body 28 has a front portion 28a located in the clutch housing 17 formed in a reduced diameter, while a rear portion 28b located in the main transmission case 53 is formed in a larger diameter shape. An attachment flange 28c is formed on the outer peripheral surface, and the attachment flange 28c is brought into contact with the rear surface of the rear wall 27 of the clutch housing 17 from the rear and is attached by an attachment bolt 29.

(Inner drive shaft 19)
The inner drive shaft 19 is formed by being divided into a front divided drive shaft piece 30 and a rear divided drive shaft piece 31, and the two divided drive shaft pieces 30, 31 are linked together in the outer drive shaft 20. The division position (interlocking connection position) between the front divided drive shaft piece 30 and the rear divided drive shaft piece 31 is set in the vicinity of the connection portion between the clutch housing 17 and the main transmission case 53, that is, in the cylindrical support body 28. It arrange | positions in the rear part 28b.

  In addition, the distal end portion of the front divided drive shaft piece 30 and the proximal end portion of the rear divided drive shaft piece 31 are interlocked and detachably interlocked.

  In other words, the front end face of the front divided drive shaft piece 30 is provided with a fitting protrusion 30a protruding rearward, while the proximal end face of the rear divided drive shaft piece 31 is formed with a proximal end fitting recess 31a. In addition, the above-mentioned fitting protrusion 30a is stamped and fitted into the proximal-side fitting recess 31a, and the spline groove 30b formed on the outer peripheral surface of the front end of the front divided drive shaft piece 30 and the rear divided drive shaft piece A cylindrical connector 32 having an axial line in the front-rear direction is spline-fitted to a spline groove 31b formed on the outer peripheral surface of the base end portion of 31.

[Outside drive shaft 20]
The outer drive shaft 20 has a front portion 20a having a small diameter along the outer peripheral surface of the inner drive shaft 19, while a rear portion 20b having a large diameter along the outer peripheral surface of the cylindrical coupling body 32. Bearings 33 and 34 are interposed between the outer peripheral surface of the rear portion 20b and the inner peripheral surface of the rear portion 28b of the cylindrical support 28.

  Moreover, the front end portion of the outer drive shaft 20 extends rearward from the rear end of the cylindrical support 28, and the PTO drive gear 20c is integrally formed on the outer peripheral surface. Reference numeral 35 denotes a PTO drive gear support bearing.

  In this way, the inner drive shaft 19 is divided into the front divided drive shaft piece 30 and the rear divided drive shaft piece 31, and the two divided drive shaft pieces 30, 31 are linked in the outer drive shaft 20. Because it is connected, the distal end of the inner drive shaft extends to a position behind the distal end of the outer drive shaft and is brought into butt contact with the proximal end of the PTO input shaft via a cylindrical shaft coupling. The clutch housing 17 and the main transmission case 53 are connected in the front-rear direction compared to the conventional technology that is interlocked and connected on the same axis, and the inside and outside double drive is provided in the clutch housing 17 and the main transmission case 53. Even when the shaft body 18 is inserted, the problem that the main transmission case 53 becomes long in the front-rear direction can be solved.

  Moreover, assembly work when the clutch housing 17 and the main transmission case 53 are connected as an assembly, maintenance work performed after the connection is released, and the like are facilitated.

  Furthermore, since the dividing position of the front divided drive shaft piece 30 and the rear divided drive shaft piece 31 of the inner drive shaft 19 is disposed in the vicinity of the coupling portion between the clutch housing 17 and the main transmission case 53, The transmission case 53 can be shortened in the front-rear direction to reduce the size of the fuselage, and the assembly unit of the main transmission case 53 can be shortened in the front-rear direction to reduce the logistics cost of the assembly unit. As a result, it is possible to carry in a large number of units at once from subcontracting.

  At this time, the fitting protrusion 30a formed at the distal end portion of the front divided drive shaft piece 30 is fitted into the proximal end fitting recess 31a formed at the proximal end portion of the rear divided drive shaft piece 31. Therefore, the front divided drive shaft piece 30 and the rear divided drive shaft piece 31 formed separately can be assembled and linked with high accuracy.

  In addition, a traveling cylindrical operating body 36 is slidably fitted back and forth over the outer peripheral surface of the outer drive shaft 20 and the outer peripheral surface of the cylindrical support body 28, and the traveling cylindrical operating body 36 is connected to the rear portion of the traveling driving actuator 36. While the base end portion of the clutch operating lever 37 is interlocked and connected, a clutch operating piece 36a is provided at the front end edge of the traveling tubular operating body 36, and the clutch operating piece 36a is connected to the passive arm 21a of the traveling clutch 21. They are placed close to each other. 38 is a lever spindle.

  In this way, when the travel clutch operating lever 37 is rotated, the travel cylindrical operating body 36 is slid forward, the clutch operating piece 36a presses the passive arm 21a, and the passive arm 21a rotates. The traveling clutch 21 is operated to be powered off.

  Further, a PTO cylindrical operating body 39 is fitted to the outer peripheral surface of the traveling cylindrical operating body 36 so as to be slidable back and forth, and a base end of the PTO clutch operating lever 40 is disposed at the rear of the PTO cylindrical operating body 39. The clutch operating piece 39a is provided at the front end edge of the PTO cylindrical operating body 39, and the clutch operating piece 39a is disposed in close proximity to the passive arm 22a of the PTO clutch 22. Yes. 41 is a lever spindle.

  In this way, when the PTO clutch operating lever 40 is rotated, the PTO cylindrical operating body 39 is slid forward, the clutch operating piece 39a presses the passive arm 22a, and the passive arm 22a rotates. Thus, the PTO clutch 22 is powered off.

[Mission part 4]
As shown in FIGS. 2 to 4, the mission unit 4 includes a main transmission mechanism 46, a sub-transmission mechanism 47, and a differential mechanism 48 in order from the front to the rear in a transmission case 45 that is extended in the front-rear direction and formed into a cylindrical shape. Is provided to form a traveling transmission mechanism 51 that can perform a main transmission and a sub-transmission, and a PTO transmission mechanism 52 is interposed between the outer drive shaft 20 and a PTO transmission portion 6 described later. Has been established.

  The transmission case 45 is divided into a main transmission case 53 containing the main transmission mechanism 46, a sub transmission case 54 containing the sub transmission mechanism 47, and a differential case 55 containing the differential mechanism 48. The front end edge of the main transmission case 53 is detachably connected to the rear end edge of the clutch housing 17 by a connecting bolt 56a, and the front end edge of the auxiliary transmission case 54 is connected to the rear end edge of the main transmission case 53. Are connected detachably by a connecting bolt 56b, and a front end edge of the differential case 55 is detachably connected to a rear end edge of the auxiliary transmission case 54 by a connecting bolt 56c.

  Hereinafter, each configuration of the above-mentioned (main transmission case 53), (main transmission mechanism 46), (sub transmission case 54), (sub transmission mechanism 47), (differential case 55), and (differential mechanism 48), This will be described in this order.

[Main transmission case 53]
As shown in FIGS. 7 and 8, the main transmission case 53 is formed in a cylindrical shape extending in the front-rear direction, and an internal support wall 57 is integrally formed on the front inner peripheral surface, and the upper, lower, left and right sides of the rear inner peripheral surface are formed. Wall receiving seats 49, 49, 49, 49 are formed on the side portions so as to bulge inwardly, and shaft support wall forming bodies 50 are connected to the rear surfaces of these wall receiving seats 49, 49, 49, 49 by connecting bolts 56d. , 56d, 56d, and 56d so that the rear end surface of the main transmission case 53 is brought into surface contact with the front end surface of the auxiliary transmission case 54 without using the coaxial support wall forming body 50, and the connection bolt 56b can be attached and detached. It is connected. 56e is a positioning protrusion.

  Here, the shaft support wall forming body 50 forms an outer peripheral edge portion along the shape of the inner peripheral surface of the rear end portion of the main transmission case 53, and is inward of the inner peripheral edge portion of the rear end portion of the main transmission case 53. The rear end surface of the main transmission case 53 can be brought into surface contact with the front end surface of the auxiliary transmission case 54.

  A main speed change mechanism 46 is interposed between the inner support wall 57 and the shaft support wall forming body 50, and the main speed change mechanism 46 performs a forward shift operation in multiple stages (five stages in this embodiment) and a reverse drive. Switching operation can be performed.

  Thus, since the shaft support wall forming body 50 is detachably attached to the inner peripheral edge of the rear end portion of the main transmission case 53, when assembling the transmission case 45, the auxiliary transmission case 54 will be described later in advance. And a differential mechanism 48, which will be described later, are incorporated in the differential case 55, while a main transmission mechanism 46 is incorporated in the main transmission case 53 via the shaft support wall forming body 50, and then the auxiliary transmission is performed. By connecting the rear end surface of the main transmission case 53 to the front end surface of the case 54 in surface contact without the shaft support wall forming body 50, the transmission case 45 can be assembled easily and reliably. 45 assembly operations can be performed efficiently.

  At this time, since it is easy to ensure the sealing performance between the end faces of the auxiliary transmission case 54 and the main transmission case 53, oil leakage can be easily prevented.

[Main transmission mechanism 46]
As shown in FIGS. 7 and 10, the main transmission mechanism 46 supports the front end portion (rear end portion) of the rear divided drive shaft piece 31 via the bearing 25 at the center portion of the internal support wall 57. A fifth speed gear 31c is integrally formed on the outer peripheral surface of the front end portion of the rear divided drive shaft piece 31 located behind 25, and a front end side fitting recess 31d is formed on the rear end surface of the rear divided drive shaft piece 31. The fitting protrusion 58a formed by projecting forward from the base end surface (front end surface) of the main transmission main shaft 58 extending in the front-rear direction is fitted in the front-end-side fitting recess 31d so as to be rotatable about its axis. On the other hand, the front end portion (rear end portion) of the main transmission main shaft 58 is supported on the center portion of the shaft support wall forming body 50 via a bearing 59 so as to be rotatable about its axis.

  The main transmission main shaft 58 is provided with fourth, third, second, and first speed gears 60, 61, 62, 63 and a reverse switching gear 64 in order from the base end side to the front end side. It is attached coaxially with an interval in the direction and rotatably around the outer peripheral surface of the main transmission main shaft 58.

  The main transmission main shaft 58 includes a third transmission body 65 disposed between the fifth speed gear 31c and the fourth speed gear 60, and a third speed gear 61 disposed between the third speed gear 61 and the second speed gear 62. A two-transmission body 66 and a first transmission body 67 disposed between the first speed gear 63 and the reverse switching gear 64 are attached.

  Here, each of the transmissions 65, 66, and 67 is connected to the main transmission main shaft 58 by the shaft-side interlocking connection pieces 65a, 66a, and 67a, and the front and rear gear-side interlocking connections that are interlocked to the front and rear adjacent gears. In the axial direction between the piece 65b, 65c, 66b, 66c, 67b, 67c, and each shaft side interlocking connection piece 65a, 66a, 67a and each gear side interlocking connection piece 65b, 65c, 66b, 66c, 67b, 67c And slide connecting pieces 65d, 66d, 67d that are slidably spline-fitted.

  Each slide connecting piece 65d, 66d, 67d is in a neutral position located on each shaft side interlocking connecting piece 65a, 66a, 67a, and each shaft side interlocking connecting piece 65a, 66a, 67a is connected to the front gear side interlocking connection. The front slide speed change position in which the two are slid between the pieces 65b, 66b, 67b and interlocked with each other, and the shaft-side interlocking connecting pieces 65a, 66a, 67a and the rear gear-side interlocking connecting pieces 65c, 66c, 67c A sliding operation is possible at any one of the rear slide speed changing positions where the both are slid in between and linked together.

  Further, between the inner support wall 57 and the shaft support wall forming body 50, a main transmission countershaft 70 extending in the front-rear direction is supported via front and rear bearings 68, 69. First, second, and third transmission gear bodies 71, 72, and 73 are coaxially and rotatably attached to the outer peripheral surface of the shaft.

  Moreover, the front gear 71a and the rear gear 71b integrally formed with the first transmission gear body 71 are engaged with the fifth speed gear 31c and the second speed gear 62, respectively, and are integrally formed with the second transmission gear body 72. The front gear 72a and the rear gear 72b are engaged with the third speed gear 61 and the second speed gear 62, respectively, and the front gear 73a formed integrally with the third transmission gear body 73 is connected to the first speed gear 63. On the other hand, the rear gear 73b integrally formed with the third transmission gear body 73 is engaged with the reverse switching gear 64 via the counter gear 74 that is pivotally supported by the shaft support wall forming body 50. 75 is a counter gear support shaft, and 76 is a shaft support provided in the main transmission case 53.

  Furthermore, between the internal support wall 57 and the shaft support wall forming body 50, as shown in FIGS. 4, 5, and 7 to 10, a slide body support shaft 80 extending in the front-rear direction is provided. A lever interlocking shaft 81 as an interlocking shaft extending in the front-rear direction is installed at a position directly above the main transmission main shaft 58, and is parallel to the right side position of the slide body support shaft 80 so as to slide back and forth. The tip of the engaging piece 82 that is movably installed and protrudes to the left from the front part of the lever interlocking shaft 81 is engaged with the engaged piece 83 provided at the front part of the slide body support shaft 80. On the other hand, an action receiving piece 84 is provided at the rear end of the lever interlocking shaft 81 extending into the auxiliary transmission case 54, and a lever interlocking mechanism 300 is provided between the action receiving piece 84 and the main speed change lever 85. Yes.

  Note that the configurations of the main transmission lever 85 and the lever interlocking mechanism 300 will be described in the explanation of the sub-transmission mechanism 47 described later for convenience.

  Further, as shown in FIG. 10, a slide restricting body 91 having a side opening 90 and formed in a C shape in the back view is fitted in the middle portion of the slide body supporting shaft 80, and the slide body supporting shaft 80 is fitted. A slide action piece 92 is projected from the shaft 80 through the side opening 90 in the radial direction.

  Moreover, the first, second, and third slide bodies 95, 94, and 93 are sequentially attached to the slide body support shaft 80 from the rear to the front so as to be slidable in the axial direction. The first and second slide bodies 95 and 94 are disposed rearward of the slide restricting body 91 while being disposed forward of the body 91.

  Furthermore, each slide body 95, 94, 93 is extended downward from the left and right sides of each boss 95a, 94a, 93a and boss 95a, 94a, 93a slidably fitted to the slide body support shaft 80. The formed shift forks 95b, 94b, 93b and slide action receiving pieces 95c, 94c, 93c formed by extending from the boss portions 95a, 94a, 93a toward the slide restricting body 91 are provided.

  The shift forks 95b, 94b, 93b of the first, second, third slide bodies 95, 94, 93 are respectively connected to the slide connecting pieces 67d of the first, second, third transmission bodies 67, 66, 65. , 66d, 65d.

  In addition, the slide action receiving pieces 95c, 94c, 93c of the first, second, and third slide bodies 95, 94, 93 rotate the slide body support shaft 80 around the axis line and the slide action piece 92 and the slide restriction. By rotating the body 91 in the required direction, the slide action piece 92 is engaged with the required one slide action receiving piece, and the slide action piece 92 is interlocked with the longitudinal sliding of the slide body support shaft 80. The slide action receiving pieces are engaged with at least one of the restriction pieces 91a and 91b projecting from the slide restriction body 91 with the other two slide action receiving pieces. It is possible to regulate the sliding operation in conjunction with the back-and-forth sliding. Reference numeral 96 denotes a restricting protrusion that is suspended from the ceiling portion 54c of the auxiliary transmission case 54 in order to restrict the movement of the slide restricting body 91 in the axial direction.

  The main transmission mechanism 46 is configured as described above, and the shift operation (first to fifth shift operation and reverse switching operation) of the main transmission mechanism 46 will be described below.

(First shift operation)
The main transmission lever 85 is pivoted backward in a state where the main transmission lever 85 is raised substantially vertically, and the operation piece 85a formed on the lower end portion of the main transmission lever 85 → the action receiving piece 84 → the lever interlocking shaft 81 → engagement piece 82 → engaged piece 83 → slide body support shaft 80, and slide body support shaft 80 is slid forward.

  Then, the sliding force in the forward direction of the slide body support shaft 80 is transmitted from the slide action piece 92 to the slide action receiving piece 95c of the first slide body 95 → the boss portion 95a → the shift fork 95b, and is transmitted to the shift fork 95b. The slide connection piece 67d of the first transmission body 67 that is interlocked and connected is slid from the neutral position to the forward slide speed change position, and the shaft side interlocking connection piece 67a and the front gear side interlocking connection piece 67b are interlocked and connected.

  As a result, the power transmitted from the engine 15 to the inner drive shaft 19 is divided into the front divided drive shaft piece 30 → the rear divided drive shaft piece 31 → the fifth speed gear 31 c → the front gear 71 a of the first transmission gear body 71 → Main transmission subshaft 70 → front gear 73a of third transmission gear body 73 → first speed gear 63 → front gear side interlocking connecting piece 67b of first transmission body 67 → slide connecting piece 67d → shaft side interlocking connecting piece 67a → The first transmission is transmitted to the main transmission main shaft 58.

  At this time, the slide action piece 92 is engaged with the slide action receiving piece 95c of the first slide body 95, and the restriction pieces 91a and 91b of the slide restriction body 91 are engaged with the second and third slide bodies 94 and 93, respectively. Engaged with the slide action receiving pieces 94c, 93c, the movement of both slide bodies 94, 93 is restricted.

(Second speed change operation)
The main speed change lever 85 is turned to the right, and the action piece 85a formed at the lower end of the main speed change lever 85 is turned to the left with the swing support piece 87 as a fulcrum, and the turning force is applied to the action receiving piece. 84 → Lever interlocking shaft 81 → engaging piece 82 → engaged piece 83 → sliding body supporting shaft 80, and the sliding body supporting shaft 80 is rotated clockwise in the rear view of FIG. The slide restricting body 91 is also rotated clockwise through the slide action piece 92.

  Subsequently, the main speed change lever 85 that is turned rightward is further turned forward to slide the slide body support shaft 80 backward.

  Then, the backward sliding force of the slide body support shaft 80 is transmitted from the slide action piece 92 → the slide action receiving piece 94c of the second slide body 94 → the boss portion 94a → the shift fork 94b, and is transmitted to the shift fork 94b. The slide connection piece 66d of the second transmission body 66 that is interlocked and connected is slid from the neutral position to the rear slide speed change position, and the shaft side interlocking connection piece 66a and the rear gear side interlocking connection piece 66c are interlocked and connected.

  As a result, the power transmitted from the engine 15 to the inner drive shaft 19 is divided into the front divided drive shaft piece 30 → the rear divided drive shaft piece 31 → the fifth speed gear 31 c → the front gear 71 a of the first transmission gear body 71 → Main transmission countershaft 70 → second gear 72b of second transmission gear body 72 → second speed gear 62 → second gear 66 rear gear side interlocking connecting piece 66c → slide connecting piece 66d → shaft side interlocking connecting piece 66a → main The transmission is transmitted to the transmission main shaft 58, and the second transmission is performed.

  At this time, the slide action piece 92 is engaged with the slide action receiving piece 94c of the second slide body 94, and the restriction piece 91b of the slide restriction body 91 is slidable by the first and third slide bodies 95 and 93. Engaged with the receiving pieces 95c, 93c, the movement of both slide bodies 95, 93 is restricted.

(Third speed change operation)
The main speed change lever 85 is turned rightward and turned rearward to slide the slide body support shaft 80 forward.

  Then, the sliding force in the forward direction of the slide body support shaft 80 is transmitted from the slide action piece 92 to the slide action receiving piece 94c of the second slide body 94 → the boss portion 94a → the shift fork 94b, and is transmitted to the shift fork 94b. The slide connection piece 66d of the second transmission body 66 that is interlocked and connected is slid from the neutral position to the forward slide speed change position, and the shaft side interlocking connection piece 66a and the front gear side interlocking connection piece 66b are interlocked and connected.

  As a result, the power transmitted from the engine 15 to the inner drive shaft 19 is divided into the front divided drive shaft piece 30 → the rear divided drive shaft piece 31 → the fifth speed gear 31 c → the front gear 71 a of the first transmission gear body 71 → Main transmission countershaft 70 → front gear 72a of second transmission gear body 72 → third speed gear 61 → front gear side interlocking connecting piece 66b → sliding connecting piece 66d → shaft side interlocking connecting piece 66a → The third transmission is performed by being transmitted to the main transmission main shaft 58.

  At this time, the slide action piece 92 is engaged with the slide action receiving piece 94c of the second slide body 94, and the defining piece 91b of the slide restriction body 91 is slid on the first and third slide bodies 95 and 93. Engaged with the action receiving pieces 95c, 93c, the movement of the slide bodies 95, 93 is restricted.

(4th shifting operation)
The main speed change lever 85 is turned to the left side, the action piece 85a formed at the lower end of the main speed change lever 85 is turned to the right side with the swing support piece 87 as a fulcrum, and the turning force is applied to the action piece. 84 → Lever interlocking shaft 81 → engaging piece 82 → engaged piece 83 → sliding body supporting shaft 80 is transmitted, and the sliding body supporting shaft 80 is rotated counterclockwise in the rear view of FIG. At the same time, the slide restricting body 91 is also rotated counterclockwise via the slide action piece 92.

  Subsequently, the main speed change lever 85 that is turned rightward is further turned forward to slide the slide body support shaft 80 backward.

  Then, the sliding force in the backward direction of the slide body support shaft 80 is transmitted from the slide action piece 92 to the slide action receiving piece 93c of the third slide body 93 → the boss portion 93a → the shift fork 93b to the shift fork 93b. The slide connection piece 65d of the third transmission body 65 that is interlocked and connected is slid from the neutral position to the rear slide speed change position, and the shaft side interlocking connection piece 65a and the rear gear side interlocking connection piece 65c are interlocked and connected.

  As a result, the power transmitted from the engine 15 to the inner drive shaft 19 is divided into the front divided drive shaft piece 30 → the rear divided drive shaft piece 31 → the fifth speed gear 31 c → the rear gear 71 b → the first transmission gear body 71. The fourth gear is transmitted from the fourth speed gear 60 to the rear gear side interlocking connecting piece 65c → the slide connecting piece 65d → the shaft side interlocking connecting piece 65a → the main transmission main shaft 58 for the fourth speed change.

  At this time, the slide action piece 92 is engaged with the slide action receiving piece 93c of the third slide body 93, and the restriction piece 91a of the slide restriction body 91 is slid on the first and second slide bodies 95 and 94. Engaged with the receiving pieces 95c, 94c, the movement of both slide bodies 95, 94 is restricted.

(Fifth shift operation)
The main speed change lever 85 is turned leftward and turned backward to slide the slide body support shaft 80 in the forward direction.

  Then, the sliding force in the forward direction of the slide body support shaft 80 is transmitted from the slide action piece 92 to the slide action receiving piece 95c of the first slide body 95 → the boss portion 95a → the shift fork 95b, and is transmitted to the shift fork 95b. The slide connection piece 65d of the third transmission body 65 that is interlocked and connected is slid from the neutral position to the forward slide speed change position, and the shaft-side interlocking connection piece 65a and the front gear-side interlocking connection piece 65b are interlocked and connected.

  As a result, the power transmitted from the engine 15 to the inner drive shaft 19 is changed to the front divided drive shaft piece 30 → the rear divided drive shaft piece 31 → the fifth speed gear 31c → the front gear side interlocking connecting piece of the third transmission 65. 65b → slide connecting piece 65d → shaft side interlocking connecting piece 65a → the main transmission main shaft 58 is transmitted, and the fifth speed change is made.

  At this time, the slide action piece 92 is engaged with the slide action receiving piece 93c of the third slide body 93, and the restriction piece 91a of the slide restriction body 91 is slid on the first and second slide bodies 95 and 94. Engaged with the receiving pieces 95c, 94c, the movement of both slide bodies 95, 94 is restricted.

(Reverse switching operation)
The main transmission lever 85 is operated to rotate forward in a state where the main transmission lever 85 is raised substantially vertically, and the operation piece 85a formed on the lower end portion of the main transmission lever 85 → the operation receiving piece 84 → the lever interlocking shaft 81 → engagement piece 82 → engaged piece 83 → slide body support shaft 80, and slide body support shaft 80 is slid backward.

  Then, the backward sliding force of the slide body support shaft 80 is transmitted from the slide action piece 92 to the slide action receiving piece 95c of the first slide body 95 → the boss portion 95a → the shift fork 95b, and is transmitted to the shift fork 95b. The slide connecting piece 65d of the third transmission body 65 that is interlocked and connected is slid from the neutral position to the rear slide speed changing position, and the shaft side interlocking connecting piece 67a and the rear gear side interlocking connecting piece 67c are interlocked and connected.

  As a result, the power transmitted from the engine 15 to the inner drive shaft 19 is divided into the front divided drive shaft piece 30 → the rear divided drive shaft piece 31 → the fifth speed gear 31 c → the front gear 71 a of the first transmission gear body 71 → Main transmission countershaft 70 → Rear gear 73b of third transmission gear body 73 → Counter gear 74 → Reverse switching gear 64 → Rear gear side interlocking connection piece 67c of first transmission body 67 → Slide connection piece 67d → Axis side interlocking connection piece 67a.fwdarw.main transmission main shaft 58, the main transmission main shaft 58 is reversely rotated, and reverse switching is performed.

  At this time, the slide action piece 92 is engaged with the slide action receiving piece 95c of the first slide body 95, and the restriction pieces 91a and 91b of the slide restriction body 91 are engaged with the second and third slide bodies 94 and 93, respectively. Engaged with the slide action receiving pieces 94c, 93c, the movement of both slide bodies 94, 93 is restricted.

[Sub-shift case 54]
As shown in FIGS. 2 to 5, 9, and 10, the auxiliary transmission case 54 is formed in a cylindrical shape that extends in the front-rear direction, and a shaft support wall 118 is formed in the middle of the inner peripheral surface. In the auxiliary transmission case 54, an auxiliary transmission mechanism 47 is disposed at a position in front of the shaft support wall 118.

  As shown in FIGS. 9 and 10, an opening 101 is formed in the upper part 54 b of the auxiliary transmission case 54, and the opening 101 is closed by a lever base cover body 301.

  That is, as shown in FIGS. 2 to 5, 9, and 10, the lever base cover body 301 includes a cover main body 302 that is formed in a lid shape and closes the opening 101, and a right side of the cover main body 302. A cylindrical laterally extending cover forming body 303 formed by extending outwardly and a cylindrical longitudinally extending cover forming body 304 formed by extending upward from the tip of the laterally extending cover forming body 303. A connecting flange portion 353 formed on the peripheral edge of the cover main body 302 is detachably attached to the upper portion of the auxiliary transmission case 54 by a connecting bolt 354.

  Then, the base of the sub-transmission lever 142 is attached to the cover body 302, and the base of the main transmission lever 85 is attached to the longitudinal extension cover forming body 304, which is in the vicinity of the sub-transmission lever 142. The base is assembled integrally with the lever base cover body 301 in proximity.

  In addition, as shown in FIG. 5, the main / sub transmission levers 85 and 142 integrally attached to the lever base cover body 301 are either on the left or right side with respect to the left / right virtual center line C1 of the mission case 45 in the aircraft traveling direction. On the other hand, in the present embodiment, they are concentrated on the right side, that is, on the right side of a driver seat 283, which will be described later, arranged at a position directly above the mission case 45.

  Here, the lever base cover body 301 includes a cover body 302, a cylindrical laterally extending cover forming body 303 formed by extending outward from the cover body 302 to the left side, and a distal end portion of the laterally extending cover forming body 303. By preparing another form formed from a cylindrical longitudinally extending cover forming body 304 formed by extending further upward, it is on the right side with respect to the left and right virtual center line C1 of the mission case 45 in the aircraft traveling direction In other words, the main and auxiliary transmission levers 85 and 142 are integrally disposed at the right side position of the driver's seat 283 as in the present embodiment. It is also possible to change to a form in which they are centrally arranged in one direction.

  Since the main transmission lever 85 is arranged in the vicinity of the auxiliary transmission lever 142 in this way, the operator holds the steering wheel 282 as a handle described later with one hand and the main transmission lever 85 with the other hand. Alternatively, the auxiliary transmission lever 142 can be operated as appropriate.

  In addition, since the main and sub transmission levers 85 and 142 are concentrated and arranged close to each other, the transition from one transmission lever operation to the other transmission lever operation can be performed quickly and reliably, and the operability can be improved. .

  Furthermore, the main transmission lever 85 and the auxiliary transmission lever 142 can be assembled integrally with their bases close to the lever base cover body 301, and then the lever base cover body 301 can be attached to the mission case 45. Therefore, both shift levers 85 and 142 can be easily interlocked and connected to the transmission case 45. As a result, the installation work efficiency of the main / sub transmission levers 85 and 142 can be improved.

  In addition, the main and sub transmission levers 85 and 142 can be integrated and concentrated at either the left side position or the right side position of the driver's seat 283 disposed immediately above the mission case 45, so that the operator's preference By arranging the main / sub transmission levers 85, 142 in either the left or right position according to the working conditions or the like, the operability of the main / sub transmission levers 85, 142 and the work efficiency can be improved.

  Hereinafter, the attachment structure of the auxiliary transmission lever 142 and the attachment structure of the auxiliary transmission mechanism 47 and the main transmission lever 85 will be described in more detail with reference to FIGS. 5, 9, and 10.

(Mounting structure of sub-transmission lever 142)
The sub-transmission lever 142 is linked to a sub-transmission mechanism 47, which will be described later, via a sub-transmission lever support shaft 141. The sub-transmission lever support shaft 141 is connected to the left and right side walls of the cover main body 302 of the lever base cover body 301. In the meantime, it is horizontally mounted with the axis line in the left-right direction, the right end 336 projects outward from the right wall, and the base end of the auxiliary transmission lever 142 is attached to the right end 336, while the auxiliary transmission lever A shift fork support shaft 135 having an axial line directed in the front-rear direction is arranged at a position directly below the support shaft 141, and a base end portion 137 of the shift fork 136 is attached to the shift fork support shaft 135 so as to be slidable back and forth. A distal end portion of an interlocking arm 143 having a base end portion connected to the auxiliary transmission lever support shaft 335 is interlocked to the end portion 137.

(Sub-transmission mechanism 47)
As shown in FIGS. 4, 7, and 9, the auxiliary transmission mechanism 47 is configured by interlockingly connecting an auxiliary transmission shaft 116 to the front end (rear end) of the main transmission main shaft 58 via a planetary gear mechanism 115. The front end of the main transmission main shaft 58 extends rearward to form a sun gear 117 that forms part of the planetary gear mechanism 115, while the auxiliary transmission shaft 116 is disposed on the same axis as the main transmission main shaft 58. In addition, the intermediate portion is supported by a shaft support 118 provided in the auxiliary transmission case 54 via a bearing 119, and the front end portion (rear end portion) is provided on a shaft support wall 100 provided in a differential case 55 described later. It is supported via a bearing 120.

  The planetary gear mechanism 115 is attached to the shaft support wall forming body 50 with a pair of front and rear inner gear supports 121 and 122 formed in a ring shape and disposed on the outer periphery of the sun gear 117 with mounting bolts 123 having an axis line in the front-rear direction. The inner gear 124 is supported between both inner gear supports 121 and 122, and a plurality of planetary gears 125 are arranged at intervals in the circumferential direction of the inner gear 124, and each planetary gear 125 is connected to the inner gear 124. And the sun gear 117, and a carrier 128 is attached between the inner peripheral edges of the pair of front and rear inner gear supports 121, and a plurality of planetary gears 125 are integrally linked to the carrier 128. .

  Moreover, the carrier 128 has a rear end edge extending rearward to form a cylindrical gear forming piece 129, and an inner tooth 130 is formed on the inner peripheral surface of the gear forming piece 129.

  Furthermore, a cylindrical shift gear support 132 is spline-fitted between the outer peripheral surface of the sun gear 117 and the outer peripheral surface of the base end portion (front end portion) 114 of the auxiliary transmission shaft 116 so as to be freely shiftable in the axial direction. Yes.

  The shift gear support 132 is engaged with the tip 138 of the shift fork 136 described above.

  In this way, by rotating the auxiliary transmission lever 142 in the front-rear direction, the shift gear support 132 is shifted in the front-rear direction so that the auxiliary transmission operation can be performed.

  That is, when the auxiliary transmission lever 142 is rotated rearward, the interlocking arm 143 is rotated forward via the auxiliary transmission lever support shaft 141, and the shift fork 136 connected to the tip of the interlocking arm 143 slides forward. As a result, the shift gear support 132 engaged with the shift fork 136 is shifted forward.

  At this time, the shift gear support 132 is shifted to a state where the shift gear support 132 is stretched between the outer peripheral surface of the sun gear 117 and the outer peripheral surface of the base end portion (front end portion) 114 of the auxiliary transmission shaft 116. Thus, the sun gear 117 and the sub-transmission shaft 116 are interlocked and connected (a state where the main transmission main shaft 58 and the sub-transmission shaft 116 are directly coupled).

  Therefore, at such a shift position, power is transmitted from the sun gear 117 integrally formed with the main transmission main shaft 58 to the sub transmission shaft 116 via the shift gear support 132.

  Further, when the auxiliary transmission lever 142 is rotated forward, the interlocking arm 143 is rotated backward via the auxiliary transmission lever support shaft 141, and the shift fork 136 connected to the tip of the interlocking arm 143 slides backward. As a result, the shift gear support 132 engaged with the shift fork 136 is shifted rearward.

  Then, the shift gear support 132 is detached from the outer peripheral surface of the sun gear 117 and is shifted onto the outer peripheral surface of the base end portion (front end portion) 114 of the auxiliary transmission shaft 116, and the front shift gear 133 is shifted to the gear forming piece 129. Is meshed with the internal teeth 130 formed on the inner peripheral surface.

  Therefore, in such a shift position, the rotational force of the sun gear 117 integrally formed with the main transmission main shaft 58 is changed from the planetary gear 125 meshed with the sun gear 117 to the carrier 128 → the gear forming piece 129 integrally formed with the carrier 128. The teeth 130 are transmitted to the front shift gear 133 of the shift gear support 132 → the shift gear support 132 → the base end portion 114 of the auxiliary transmission shaft 116.

  At this time, the decelerated power is transmitted from the main transmission main shaft 58 to the sub transmission shaft 116 via the planetary gear mechanism 115 to perform the sub transmission.

(Main shift lever 85 mounting structure)
As shown in FIGS. 5, 9, and 10, the main transmission lever 85 is interlocked to the lever interlocking shaft 81 via the lever interlocking mechanism 300, and the lever interlocking mechanism 300 is connected to the lever base cover body. It is arranged in 301.

  That is, the lever interlocking mechanism 300 is configured such that the interlocking rod 305 extending in the left-right direction is slidable in the left-right direction between the left side wall of the cover main body 302 and the right side wall of the longitudinally extending cover forming body 304 and is rotated about its axis. The interlocking shaft side action piece 306 protrudes downward from the left side portion of the interlocking rod 305 located in the cover main body 302, and the lower end portion of the interlocking shaft side action piece 306 is linked to the lever. While engaging with the upper end of the interlocking shaft side action receiving piece 84 provided at the rear end of the shaft 81, the lever side action receiving piece 307 is provided at the right end of the interlocking rod 305 located in the longitudinally extending cover forming body 304. The lever-side action receiving piece 307 is engaged with the lower end portion of the lever-side action piece 85a.

  A cylindrical swing receiving portion 308 is connected to the upper end portion of the longitudinally extending cover forming body 304, and a substantially spherical swing support body 309 is placed in the swing receiving portion 308 in any direction, front, rear, left, and right. A through hole 310 that penetrates in the vertical direction is formed in the center of the swing support 309, and the lever side action piece 85a is inserted into the through hole 310, and the lever The middle part of the side action piece 85a is connected to the swing support 309 via a support shaft 311 that passes through the swinging support 309 in the left-right direction with the axis line extending. 312 is a swing support pressing spring interposed between the swing receiver 308 and the swing support 309, and 313 is a flexible cover that covers the lever side action piece 85a.

  Further, the main transmission lever 85 is connected to the upper end portion of the lever side action piece 85a with the lower end portion and is connected via the connecting pin 332.

  In this way, by grasping the upper end portion of the main transmission lever 85 and rotating the main transmission lever 85 in the front-rear and left-right directions, the lower end portion of the lever-side action piece 85a via the swing support 309. Can be swung back and forth and left and right.

  Then, by swinging the lever side action piece 85a in the front-rear direction, the lever interlocking shaft 81 is moved via the lever side action receiving piece 307 → the interlocking rod 305 → the interlocking shaft side action piece 306 → the interlocking shaft side action receiving piece 84. It can be slid back and forth.

  Further, by swinging the lever side action piece 85a in the horizontal direction, the lever interlocking shaft 81 is moved via the lever side action receiving piece 307 → the interlocking rod 305 → the interlocking shaft side action piece 306 → the interlocking shaft side action receiving piece 84. It can be rotated around its axis.

  Therefore, the main shift lever 85 can easily perform the five-stage shift operation described above.

  Here, between the cover main body 302 and the left end portion of the interlocking rod 305, as shown in FIGS. 5 and 10, the shifting operation in the left-right direction of the main transmission lever 85 is changed to the shifting operation direction branch position in the neutral position. A branch position temporary fixing portion 314 for temporarily fixing is provided.

  That is, as shown in FIG. 10, the branch position temporary fixing portion 314 is formed in the left side portion of the ceiling portion 315 of the cover body 302 by penetrating a ball containing vertical hole 316 extending in the vertical direction. The lower end of the temporary fixing ball 319 protrudes from the lower end opening 317 of the hole 316 via the pressing spring 318, while the left engaging groove 320, the central engaging groove 321 and the right side are formed on the outer peripheral surface of the left end of the interlocking rod 305. The engaging groove 322 is formed adjacent to the left and right direction, and the lower end portion of the temporary fixing ball 319 is engaged in any of the engaging grooves. A spring holder 436 holds the pressing spring 318 from above, and is fixed to the ball housing vertical hole 316.

  Thus, when the main transmission lever 85 is operated to the neutral position, the interlocking rod 305 slides, and the lower end portion of the temporary fixing ball 319 is engaged with the central engagement groove 321. When the lever is rotated to the left (right) side, the interlocking rod 305 slides to the right (left) side, and the lower end of the temporary fixing ball 319 is moved to the left (right) side engaging groove 320 (322). To engage.

  Accordingly, the operator can feel as a response that the main transmission lever 85 has been shifted to the transition operation position even in the neutral position. As a result, the operability of the main transmission lever 85 can be improved.

  Further, as shown in FIG. 7, the shift operation of the main transmission lever 85 in the front-rear direction is performed between the upper portion of the inner support wall 57 of the main transmission case 53 and the front end of the slide body support shaft 80 at each shift position. A shift position temporary fixing portion 323 for temporarily fixing is provided.

  That is, an insertion support hole 324 for inserting and supporting the front end portion of the slide body support shaft 80 is formed in the upper part of the inner support wall 57 of the main transmission case 53, and the inner support wall 57 is inserted into the inner support wall 57 from the upper peripheral surface of the insertion support hole 324. A ball receiving vertical hole 325 is formed upward, and the lower end of the temporary fixing ball 328 protrudes from the lower end opening 326 of the ball receiving vertical hole 325 via the pressing spring 327, while the slide body support shaft 80 A front engagement groove 329, a central engagement groove 330, and a rear engagement groove 331 are formed adjacent to each other in the front-rear direction on the outer peripheral surface of the front end portion, and the lower end of the temporary fixing ball 328 is located in any of the engagement grooves The parts are engaged.

  Thus, when the main speed change lever 85 is operated to the neutral position, the slide body support shaft 80 slides, and the lower end portion of the temporary fixing ball 328 is engaged with the central engagement groove 330, and the main speed change is made from the same state. When the lever 85 is rotated forward (rear), the slide body support shaft 80 slides forward (rear), and the lower end of the temporary fixing ball 328 is inserted into the rear (front) engagement groove 331 (329). The parts are engaged.

  Therefore, the operator can feel as a response that the gear is being shifted to each shift position. As a result, the operability of the main transmission lever 85 can be improved.

  Further, an opening 102 is formed in the bottom 54d of the auxiliary transmission case 54, and a front wheel drive power take-out portion 103, which will be described later, is attached through the opening 102, and the front wheel drive power take-out portion 103 is attached. Are linked to the sub-transmission mechanism 47, respectively.

[Differential case 55]
As shown in FIGS. 11 and 12, the differential case 55 is formed in a box shape having an opening on the upper surface, and openings 104 and 104 are formed in the left and right side walls 55a and 55b, respectively, and the rear axle case is formed through the openings 104 and 104. 8, 8 are connected to each other, and rear axles 105, 105 extending in the left-right direction are inserted into the rear axle cases 8, 8 and supported rotatably. The rear axles 105, 105 are linked to the differential mechanism 48. ing.

  The differential case 55 forms a front wall with the shaft support wall 100, and supports the rear end portion of the auxiliary transmission shaft 116 and the middle portion of the third divided transmission shaft 247 with the coaxial support wall 100.

  In addition, as shown in FIGS. 11 and 12, the differential case 55 is formed with a maintenance opening 106 in the ceiling, and a lift arm support 339 is detachably attached to the peripheral edge of the opening 106. The hydraulic circuit body 341 is detachably attached to a hydraulic circuit body support piece 340 formed by extending the lift arm support body 339 forward, and the hydraulic control valve 342 is attached to the hydraulic circuit body 341.

  Thus, since the hydraulic circuit body 341 and the hydraulic control valve 342 are formed separately from the lift arm support 339, even when a burrow is formed in the lift arm support 339 formed by casting, Since pressure oil is not passed through the lift arm support 339, there is no need to worry about adverse effects due to burrows such as oil leakage.

  Moreover, when forming the lift arm support 339, it is easy to take measures against the formation of burrows, and the yield of the lift arm support 339 can be improved, and the manufacturing cost can be reduced.

  Furthermore, the lift arm support 339 itself can be made as small as possible, facilitating the handling in manufacturing and processing, and reducing the manufacturing cost.

  Since the hydraulic circuit body 341 and the hydraulic control valve 342 can be attached and detached without removing the lift arm support 339, which is a relatively heavy object, from the transmission case 45, the maintainability is improved.

  In addition, since the hydraulic circuit body 341 is mounted and fixed on the hydraulic circuit body support piece 340 formed by extending the lift arm support body 339 forward, the lift arm support body 339 is attached to the transmission case 45 in advance. The hydraulic circuit body 341 can be fixed to the hydraulic circuit body support piece 340 in a state where the hydraulic circuit body 341 is fixed to the hydraulic circuit body support piece 340 in advance. It can also be attached to, and assembly work can be performed efficiently according to work conditions and the like.

  Since the hydraulic control valve 342 is attached to the hydraulic circuit body 341, the hydraulic control valve 342 and the hydraulic circuit body 341 can be arranged in a compact and concentrated manner, and they can be integrated with the lift arm support 339. Or it can fix to the hydraulic circuit body support piece 340, and can improve these assembly performance.

  In addition, the hydraulic circuit body 341 that is separated from the lift arm support 339 can be provided with a centralized arrangement of valves and can be made compact.

  Next, the configuration of the lift arm support 339, the hydraulic circuit body 341, and the hydraulic control valve 342 will be specifically described with reference to FIGS.

(Lift arm support 339)
As shown in FIGS. 13 to 16, the lift arm support 339 includes a ring-shaped attachment piece 343 for attaching to the peripheral portion of the opening 106 formed in the ceiling portion of the differential case 55, and the attachment piece A cylindrical hydraulic circuit body support piece 340 that rises upward at the front of 343 and supports the hydraulic circuit body 341, and a pair of left and right that rises upward at the rear of the mounting piece 343 and pivotally supports the lift arm spindle 344 And pivot pieces 345, 345.

  The mounting piece 343 is provided with mounting bolts as a plurality (ten in this embodiment) of mounting holes positioned between the left and right sides of the pair of left and right pivot support pieces 345, 345 and both pivot support pieces 345, 345. A hole 346 is formed, and a mounting bolt hole 346 between both pivot pieces 345 and 345 is disposed close to a lift arm spindle 344 pivotally supported by the pivot pieces 345 and 345.

  That is, as shown in FIGS. 14 and 16, one mounting bolt hole 346 is formed at the front end portion of the mounting piece 343, and the left and right virtual center line C2 extending in the front-rear direction through the center of the mounting bolt hole 346. Four mounting bolt holes 346 are formed at left and right symmetrical positions at regular intervals in the front-rear direction, and one mounting bolt hole 346 is formed at the rear of the mounting piece 343 located on the left and right virtual center line C2. The rear mounting bolt hole 346 has a concave portion 347 in which an upper portion and a rear portion are opened in a portion of the mounting piece 343 located between the pair of left and right pivot support pieces 345 and 345 and immediately below the lift arm support shaft 344. And is formed in the concave portion 347.

  Thus, sufficient strength can be ensured by the wall shape of the pivot pieces 345, 345, so that it is not necessary to form walls on the mounting pieces 343 other than the pivot pieces 345, 345.

  A mounting bolt hole 346 formed between the pair of left and right pivot pieces 345, 345 formed in the mounting piece 343 is located between the pair of left and right pivot pieces 345, 345 and directly below the lift arm spindle 344. The mounting bolt hole 346 formed between the pivot pieces 345 and 345 is disposed close to the lift arm spindle 344 pivotally supported by the pivot pieces 345 and 345 in order to form the recess 347 formed in the portion 343. Even when a tensile load is applied to the lift arm spindle 344, no bending moment acts on the rear part of the mounting piece 343, so the mounting piece 343 is made thinner and lighter. Can be achieved.

  Moreover, the mounting bolt holes 346 can be formed in the mounting piece 343 in a balanced manner in the front-rear and left-right positions, and the mounting strength of the mounting piece 343 can be ensured.

  Furthermore, all the mounting bolt holes 346 can be formed in the mounting piece 343 from above, and the processing can be facilitated.

  Since the attachment work of the attachment piece 343 can be performed with one type of tool, the attachment work of the attachment piece 343 can be simplified.

  Further, the lift arm support shaft 344 can be manufactured at low cost because it can be formed with only a compact upper and lower mold without requiring a core and without extending the attachment piece 343 rearward. .

  As shown in FIG. 15, support shaft insertion holes 348 and 348 that open in the left and right directions are formed in the upper portions of the pair of left and right pivot support pieces 345 and 345, respectively. The arm support shaft 344 is inserted in a penetrating state and mounted horizontally, and the base ends of the lift arms 350 and 350 are attached to the left and right end portions 349 and 349 of the lift arm support shaft 344, respectively, as shown in FIGS. In addition, lift cylinders 351 and 351 that extend in the vertical direction are interposed between the middle part of each lift arm 350 and 350 and the lower part of the differential case, respectively, and the lift arms 350 and 350 can be vertically rotated by both lift cylinders 351 and 351. .

  The lift cylinders 351 and 351 for vertically moving the lift arms 350 and 350 are hydraulically controlled by a hydraulic control valve 342 via a hydraulic circuit body 341.

  The lift cylinder 351 employs a single-acting cylinder, is extended by supplying pressure oil, rotates the lift arm 350 upward, and discharges the pressure oil to lift the lift arm 350. The lift arm 350 is rotated downward by a shortening operation due to its own weight of a work machine (not shown) connected to.

  Further, grease nipples 352 and 252 as lubricating oil supply portions for supplying lubricating oil to the lift arm supporting shaft 344 are provided at the upper end portions of the respective pivot support pieces 345 and 345.

  In this way, grease or the like as lubricating oil is applied to the outer peripheral surface of the lift arm spindle 344 supported by each pivot piece 345 from the grease nipples 352 and 352 provided at the upper ends of the pivot pieces 345 and 345. By supplying (lubricating), it is possible to satisfactorily ensure the rotation performance of the lift arm support shaft 344 that is horizontally mounted between the two pivot support pieces 345 and 345.

  Moreover, the lift arm support 339 can secure sufficient strength due to the wall shape of the pivot support pieces 345 and 345. As a result, no walls are required except for the portions of the pivot support pieces 345 and 345 that support the lift arm support shaft 344. Therefore, the weight can be reduced.

(Hydraulic circuit body 341)
As shown in FIGS. 13 and 16 to 18, the hydraulic circuit body 341 is formed of a block-shaped circuit body main body 355 and a connecting flange portion 356 integrally formed at the lower peripheral edge of the circuit body main body 355. ing.

  As shown in FIG. 16 (b), the circuit body 355 is formed with an upper oil passage forming surface portion 357 at the upper portion and a lower oil passage forming surface portion 358 at the lower portion as shown in FIG. 16 (a). One of the upper oil passage connecting vertical oil passages 359 is formed in the center of the left side and extends in the vertical direction, and the upper end of the upper oil passage connecting vertical oil passage 359 is connected to the upper oil passage forming surface portion 357. The lower oil passage connecting vertical oil passage 360 extending in the vertical direction at the rear center is formed, and the upper end portion of the lower oil passage connecting vertical oil passage 360 is connected to the lower oil passage forming surface portion 358. The lower ends of the oil passages 359 and 360 are connected to a hydraulic control valve 342 described later.

  Next, for convenience of explanation, first, the lower layer oil passage forming surface portion 358 will be described, then the upper layer oil passage forming surface portion 357 will be described, and then the connection between them will be described.

  That is, the lower layer oil passage forming surface portion 358 forms an oil passage extending in the front-rear direction or the left-right direction on the same horizontal plane at the lower part of the circuit body main body 355, as shown in FIG. 16 (a). The rear extension oil passage 361 formed by extending rearward from the front center portion of the lower part of the circuit body 355, and the front left and right extension extending in the left-right direction perpendicular to the rear end portion of the rear extension oil passage 361 An oil passage 362, a rear left extension oil passage 363 formed by extending from the rear right end portion to the left side in parallel with the front left and right extension oil passages 362, and a left end of the rear left extension oil passage 363. After the rear center part front extension oil passage 364 is formed to extend forward from the rear center part perpendicular to the part, and after being formed to extend forward from the rear left side part in parallel with the rear center part front extension oil passage 364 A left front forward extending oil passage 365 is formed.

  The front end portion of the rear center forward extension oil passage 364 is connected to the upper end portion of the lower oil passage connecting vertical oil passage 360, while the front end portion of the rear left portion front extension oil passage 365 is connected to the upper oil passage connecting vertical passage. It is connected to the middle part of the oil passage 359.

  In addition, a pump connection portion 366 that connects to a gear pump (not shown) is provided at the front end portion of the rear extension oil passage 361, and a relief valve 367 is provided at the left end portion of the front left and right extension oil passages 362. A feed valve connecting portion 368 connected to a sub-control valve (not shown) is provided at the right end of the left and right extending oil passage 362. A return side valve connecting portion 369 that connects to the sub-control valve is provided at the right end of the rear left side extending oil passage 363. A single-acting pressure oil external connection connecting portion 370 is provided in communication with the rear portion of the rear left front forward extending oil passage 365.

  As shown in FIG. 16 (b), the upper layer oil passage forming surface portion 357 forms an oil passage extending in the front-rear direction or the left-right direction on the same horizontal plane in the upper part of the circuit body main body 355. The first, second, third, and fourth rearward extending oil passages 371, 372, 373, and 374 extending backward from the front end of the upper portion of the body body 355 are formed at intervals in the left-right direction. First, second, and third left side extending oil that forms a right side extending oil passage 375 extending toward the right side from the left side end and that extends toward the left side from the upper right end of the circuit body main body 355. Roads 376, 377, and 378 are formed, and a rear left and right through oil passage 379 that penetrates in the left and right direction is formed in the rear part of the circuit body main body 355.

  The first rear extending oil passage 371 has a front portion orthogonal to the left side portion of the right extending oil passage 375 and a rear end portion connected to the upper end portion of the upper oil passage connecting vertical oil passage 359.

  The second rear extension oil passage 372 has a rear end portion connected to the center of the rear left and right through oil passage 379, and a flow rate adjustment valve 380 is provided at the front portion. The middle portion is connected to the left end of the second left extension oil passage 377, and the rear portion is connected to the left end of the third left extension oil passage 378. 3 A safety valve 382 is provided on the left extension oil passage 378.

  The third rear extension oil passage 373 has a rear end connected to the right end of the right extension oil passage 375 and a midway portion connected to the left end of the first left extension oil passage 376. Is provided with a check valve 383.

  The fourth rear extension oil passage 374 has a midway portion orthogonal to the first left extension oil passage 376 and a rear end portion connected to the right side of the second left extension oil passage 377.

  Also, lift cylinder connecting portions 384 and 384 are provided at the left and right ends of the rear left and right through oil passages 379, respectively, and the lift cylinder connecting portions 384 and 384 and the lift cylinders 351 and 351 are connected via hydraulic pipes (not shown). Connected.

  As shown in FIGS. 17 and 18, a tank side return vertical oil passage 385 as a drain circuit penetrating in the vertical direction is formed at the left rear portion of the circuit body main body 355, and the tank side return vertical oil passage 385 is formed. A tank connecting part 386 is provided at the upper end of the tank, and a hydraulic tank (not shown) is connected to the tank connecting part 386 via a hydraulic pipe, while the lower end of the tank-side return vertical oil passage 385 will be described later. The valve cover body 387 is opened. Reference numeral 388 denotes a relief drain oil passage. The relief drain oil passage 388 has an upper end connected to a rear end of the rear extending oil passage 361 and a lower end opened in a valve cover body 387 described later.

  In this way, the pressure oil pumped from the gear pump to the pump connection portion 366 is rearward extension oil passage 361 → front left / right extension oil passage 362 → feed valve connection portion 368 → sub control valve (not shown) → return. Side valve connecting part 369 → rear left side extending oil passage 363 → rear center front extending oil passage 364 → lower oil passage connecting vertical oil passage 360 → hydraulic control valve 342 → upper oil passage connecting vertical oil passage 359 → first Rear extension oil passage 371 → Right extension oil passage 375 → Third rear extension oil passage 373 → Check valve 383 → First left extension oil passage 376 → Fourth rear extension oil passage 374 → Second left extension oil passage 377 → Flow rate adjustment The valve 380 → the second rear extending oil passage 372 → the rear left and right through oil passages 379 → the lift cylinder connecting portions 384 and 384 → the lift cylinders 351 and 351 are pressure-fed so that the lift cylinders 351 and 351 can be extended.

  Further, the pressure oil in each lift cylinder 351, 351 is the lift cylinder connecting portion 384,384 → the rear left and right through oil passage 379 → the second rear extension oil passage 372 → the flow rate adjusting valve 380 → the right extension oil passage 375 → the first rear extension oil. Road 371 → Upper oil passage vertical oil passage 359 → Hydraulic control valve 342 → Valve cover body 387 to be described later → Tank side return vertical oil passage 385 → Tank connection portion 386 → Hydraulic pipe → Return to the hydraulic tank I am doing so.

  At this time, supply of pressure oil to the lift cylinders 351 and 351 and discharge of the pressure oil can be performed by a switching operation of a hydraulic control valve 342 described later.

  As described above, the upper body oil passage forming surface portion 357 and the lower layer oil passage forming surface portion 358 are formed in the upper and lower layers in the circuit body main body 355, and the oil passage forming surface portions 357 and 358 have the front and rear direction and the left and right directions. An oil passage extending in the direction and connecting the required oil passages orthogonally to each other, and further, an oil passage extending in the vertical direction is formed in the circuit body 355 to form an upper oil passage forming surface portion 357. Since one of the oil passages formed on the lower oil passage formation surface portion 358 and a hydraulic control valve 342, which will be described later, are connected in an orthogonal state, the formation of the hydraulic circuit in the circuit body 355 is simple and reliable. It can be carried out.

  Here, the oil passage is not limited to the front-rear direction and the left-right direction as long as it is in the same plane, and can be formed by being adapted to the extension direction of the hydraulic pipe to be connected and extending in a required direction. As a result, hydraulic pipe connection work and piping work can be facilitated.

  Further, the connecting flange portion 356 of the hydraulic circuit body 341 is formed so that the upper surface of the hydraulic circuit body support piece 340 formed on the lift arm support body 339 can be closed, as shown in FIGS. A plurality of bolt insertion holes 390 are formed at the peripheral edge.

  A plurality of bolt screw holes 391 that coincide with the bolt insertion holes 390 are formed on the upper end surface of the hydraulic circuit body support piece 340, and the bolt insertion holes 356 of the connecting flange portion 356 are inserted into the bolt screw holes 391. The hydraulic circuit body 341 is detachably connected to the hydraulic circuit body support piece 340 by matching the holes 390 and screwing the connecting bolts 392 into the holes 390 and 391.

(Hydraulic control valve 342)
As shown in FIGS. 17 and 18, the hydraulic control valve 342 includes a valve main body 395 and a spool 396 interlocked with the valve main body 395. A spacer 397 is provided on the lower surface of the hydraulic circuit body 341. A valve body 395 is attached in a suspended state, and a spool 396 projects backward from the valve body 395.

  Then, a valve cover body 387 is attached to the lower surface of the hydraulic circuit body 341, the hydraulic control valve 342 is accommodated in the valve cover body 387, and a drain of the hydraulic control valve 342 is formed in the valve cover body 387. Through the drain receiving space S, it is possible to discharge through the tank side return vertical oil passage 385 as a drain circuit.

  Moreover, the drain discharged through the valves provided in the hydraulic circuit body 341 is collected in the drain receiving space S.

  Here, the valve cover body 387 is formed in a top-opening box shape, and an upper edge 389 is attached to the lower surface of the hydraulic circuit body 341 in a sealed state by a mounting bolt 398 and sealed to the rear wall of the valve cover body 387. A spool projection hole 400 is formed through the piece 399, and the tip end portion of the spool 396 projects from the spool projection hole 400 so as to be slidable back and forth.

  The spool 396 is elastically biased in the protruding direction by the pressing spring 401.

  In this manner, the valve cover body 387 is attached to the hydraulic circuit body 341 that is detachably attached to the lift arm support body 339, and the hydraulic control valve 342 is accommodated in the valve cover body 387. Before being incorporated into the arm support 339, the performance and function of the hydraulic control valve 342 can be inspected alone.

  As a result, it is possible to facilitate performance / function inspection, downsizing of the inspection apparatus, and easy handling by human power.

  Further, as shown in FIGS. 13, 17 and 18, the valve cover body 387 is mounted in a state where the hydraulic circuit body 341 is attached to the hydraulic circuit body support piece 340 and is suspended from the hydraulic circuit body 341. A lower part 402 of the valve cover body 387 is disposed in the mission case 45.

  In this way, since the hydraulic circuit body 341 is attached to the differential case 55 via the lift arm support 339, the seal of the mounting surface of the lift arm support 339 to the differential case 55 is at one place, The sealing method can be adopted.

  Moreover, since the lower portion 402 of the valve cover body 387 is disposed in the differential case 55, the ground height of the hydraulic circuit body 341 can be set low, and the driver's seat is disposed immediately above the hydraulic circuit body 341. A large degree of freedom in designing the mounting height of 283 can be secured.

  The spool 396 of the hydraulic control valve 342 described above can be operated by a lift lever 404 (see FIG. 15) via a spool operating piece 403 provided at the rear of the hydraulic circuit body support piece 340, and a feedback link mechanism 405. As a result, the lift is stopped.

  That is, as shown in FIGS. 13, 15, and 16, a rod-shaped spool operating piece 403 is slid forward and backward in an operating piece insertion hole 406 formed in the rear portion of the hydraulic circuit body supporting piece 340. The spool actuating piece 403 is movably inserted and is disposed opposite to the spool 396 of the hydraulic control valve 342 in the front-rear direction on the same axis.

  In addition, the rear portion of the spool operating piece 403 is supported by the mounting piece 343 via the operating piece support 407, and the central portion of the swinging piece 408 extending in the left-right direction is vertically moved to the rear end portion of the spool operating piece 403. The left and right engagement pins 410 and 411 protrude upward at the left and right ends of the swing piece 408, respectively, and are fed back to the left engagement pin 410. The left engagement pin 412 of the mechanism 405 is engaged from behind, while the right engagement pin 413 interlocked with the lifting lever 404 is engaged with the right engagement pin 411 from behind.

  The feedback link mechanism 405 is provided with a left boss portion 414 extending in the left-right direction on the rear left side of the mounting piece 343, and the left interlocking shaft 415 is inserted into the left boss portion 414. The base end of the interlocking arm 416 is attached to the end, the tip of the connecting rod 417 is connected to the tip of the interlocking arm 416 so that the connecting position can be adjusted, and the rear end of the connecting rod 417 is connected to the lift arm support. The shaft 109 is connected to the tip of an interlocking piece 418 that protrudes upward from the left end of the shaft 109. Reference numerals 419 and 420 denote connecting pins, and 421 denotes a fixing bolt.

  On the other hand, a left interlocking projecting piece 422 is projected downward from the right end of the left interlocking shaft 415, and the left engaging pin 412 projects from the lower end of the left interlocking projecting piece 422 to the right. Has been established.

  Further, a right boss portion 423 extending in the left-right direction is provided on the rear right side portion of the mounting piece 343, the right interlocking shaft 424 is inserted into the right boss portion 423, and the lifting lever is attached to the right end portion of the right interlocking shaft 424. While the base end portion of 404 is interlocked and connected, a right interlocking projecting piece 425 is protruded downward from the left end portion of the right interlocking shaft 424 and the above-mentioned rightward interlocking projecting piece 425 is directed leftward from the lower end portion thereof. A right engaging pin 413 is projected.

  Here, the lifting lever 404 is centrally arranged on the right side of the driver's seat 283 in the same manner as the main / sub transmission levers 85 and 142 described above, and the operability of the levers 85, 142 and 404 is ensured satisfactorily.

  In this way, when the raising / lowering lever 404 is rotated backward to perform the raising operation, the right engagement pin 413 engages with the right engagement pin 411 from the rear, and via the right engagement pin 411 The right end of the swing piece 408 is pressed forward.

  At this time, since the left end portion of the swing piece 408 is fixed by the left engagement action pin 412 via the left engagement pin 410, the center part of the swing piece 408 is provided via the pivot pin 409. The coupled spool operating piece 403 is slid forward, and the spool 396 is slid forward against the elastic biasing force of the pressing spring 401.

As a result, the valve body 395 is opened upward, pressure oil is pumped to the lift cylinders 351, 351, both lift cylinders 351, 351 are extended, and lift arms 350 , 350 linked to the lift cylinders 351, 351 are lifted. Move.

Then, the feedback link mechanism 405 is interlocked with the upward rotation of the lift arms 350 , 350 , and the left engagement action pin 412 of the feedback link mechanism 405 is rotated rearward, so that the swing piece 408 via the left engagement pin 410 is rotated. As a result, the spool 396 slides backward by the elastic urging force of the pressing spring 401 and returns to the neutral position. Stop the flow of pressurized oil.

  Further, when the elevating lever 404 is rotated forward to perform the lowering operation, the right engaging pin 413 is separated from the right engaging pin 411.

As a result, the spool 396 is slid rearward by the elastic biasing force of the pressing spring 401, the valve body 395 is opened to the lower side, and the pressure oil pumped to the lift cylinders 351 and 351 is discharged, and both lifts The cylinders 351 and 351 are shortened, and the lift arms 350 and 350 linked to the lift cylinders 351 and 351 are rotated downward.

  At this time, since the left end portion of the swing piece 408 is fixed by the left engagement action pin 412 via the left engagement pin 410, the center part of the swing piece 408 is provided via the pivot pin 409. The coupled spool operating piece 403 is slid rearward, and the right end of the swinging piece 408 is moved rearward via the right engaging pin 411.

Then, the feedback link mechanism 405 is interlocked with the downward rotation of the lift arms 350 , 350 , and the left engagement pin 412 of the feedback link mechanism 405 is rotated forward, and the swing piece 408 via the left engagement pin 410 is rotated. As a result, the spool 396 is slid forward against the elastic urging force of the pressing spring 401, and when the valve 395 returns to the neutral position, the valve body 395 is closed and lift cylinders 351, 351 Stop the flow of pressure oil to

  Here, the feedback link mechanism 405 can adjust the neutral position of the spool 396 by adjusting the coupling position between the distal end portion of the interlocking arm 416 and the distal end portion of the coupling rod 417.

  Also, as shown in FIG. 11, an opening 111 is formed at the rear end of the differential case 55, and a PTO transmission 6 is attached to the opening 111. The configuration of the PTO transmission 6 will be described later. .

[Differential mechanism 48]
As shown in FIGS. 11 and 12, the differential mechanism 48 is interposed between the auxiliary transmission shaft 116 and the pair of left and right rear axles 105, 105. The differential mechanism 48 extends rearward from the shaft support wall 100. An output bevel gear 180 is integrally formed at the front end portion (rear end portion) of the transmission shaft 116, and the rear axle input gears 181 and 181 are attached to the base end portions of the rear axles 105 and 105 so that the output bevel gear 180 is a differential mechanism. 48, the rear axle input gears 181 and 181 are linked to each other.

  That is, the differential mechanism 48 has a large reduction gear 183 that meshes with the output bevel gear 180 attached to the outer peripheral surface of the differential case 182, while the differential case 182 has a small differential gear support shaft 184 that extends in the front-rear direction. A pair of front and rear small differential gears 185 and 185 are rotatably mounted, and a pair of left and right large differential gears 187 and 187 are mounted via a pair of left and right large differential gear support shafts 186 and 186. 187 and 187 are meshed with both small differential gears 185 and 185.

  The cylindrical communication connecting pieces 188, 188 integrally formed on the left and right side portions of the differential case 182 are detachably fitted with a pair of left and right cylindrical shaft supports 189, 189 with their axis lines in the left-right direction so that they can be connected and connected. The large differential gear support shafts 186, 186 are inserted into and supported by the cylindrical shaft support members 189, 189 through the respective cylindrical communication connecting pieces 188, 188, and the cylindrical shaft supports of the large differential gear support shafts 186, 186 are supported. Transmission gears 190 and 190 that mesh with the rear axle input gears 181 and 181 are attached to the portions that protrude from the bodies 189 and 189, respectively, and the front ends of the large differential gear support shafts 186 and 186 are brakes for traveling 192 and 192 of brake portions 191 and 191 described later, respectively. Is detachably connected.

  In this way, the rotational force transmitted to the auxiliary transmission shaft 116 is the output bevel gear 180 integrally formed at the front end (rear end) of the auxiliary transmission shaft 116 → the large reduction gear 183 → the differential case 182 → the small Differential gear support shaft 184 → Small differential gear 185,185 → Each large differential gear 187,187 → Each large differential gear support shaft 186,186 → Each transmission gear 190,190 → Each rear axle input gear 181,181 → Each rear axle 105,105 → Each rear wheel 9 and 9 are transmitted.

  The pair of left and right cylindrical shaft supports 189 and 189 are fitted from the outside into mounting openings 194 and 194 formed on the left and right side walls 55a and 55b of the auxiliary transmission case 54, and are detachably attached by mounting bolts 195 and 195. The differential case 182 is detachably mounted between the two cylindrical shaft supports 189 and 189.

  The cylindrical shaft supports 189 and 189 can be removed from the auxiliary transmission case 54 by pulling outward from the mounting openings 194 and 194 after the mounting bolts 195 and 195 are removed. The support shafts 186 and 186 can also be removed by being pulled out of the differential case 182 integrally with the cylindrical shaft supports 189 and 189.

  Therefore, the differential case 182 that is detachably mounted between the cylindrical shaft supports 189 and 189 has a maintenance opening formed in the ceiling of the auxiliary transmission case 54 after the cylindrical shaft supports 189 and 189 are removed. 106 can be taken out.

  In addition, the brake unit 191 has a traveling brake 192 disposed in the brake case 196 so that the traveling brake 192 can be braked and released by the brake operating lever 198 via the brake action piece 197. ing. Reference numeral 199 denotes a brake lever support shaft pivotally supported on the brake case 196.

  The brake case 196 is detachably attached in a state of being spanned between the side wall of the auxiliary transmission case 54 and the outer peripheral surface base portion of the rear axle case 8, and the brake case 196 is removed from the brake case 196, thereby The traveling brake 192 can be detached from the tip of the large differential gear support shaft 186 integrally with the case 196.

  Next, the front wheel driving power take-out unit 103 will be described with reference to FIGS.

[Front wheel drive power extractor 103]
As shown in FIGS. 4 and 9, the front wheel drive power take-out part 103 is attached to the opening part 102 formed in the bottom part of the auxiliary transmission case 54, and a pair of front and rear parts are mounted in the take-out part case 160. The front wheel drive shaft 164 with its axis line oriented in the front-rear direction via the bearings 162 and 163 is installed, and the input gear 165 is attached to the middle portion of the front wheel drive shaft 164, and the rear portion of the input gear 165 and the auxiliary transmission shaft 116 The first and second intermediate gears 167 and 168 are interposed between the output gear 166 and the output gear 166 attached thereto.

  Here, the first intermediate gear 167 is rotatably attached to a PTO transmission shaft 169, which will be described later, via a bearing 170, and the second intermediate gear 168 is a pair of front and rear formed by protruding into the auxiliary transmission case 54. A gear support shaft 173 is installed on the gear support pieces 171 and 172, and is rotatably attached to the gear support shaft 173 via a bearing 174.

  The output gear 166, the first intermediate gear 167, the second intermediate gear 168, and the input gear 165 are interlocked and connected in series.

  Further, the front wheel drive shaft 164 projects the front end portion 175 forward from the extraction portion case 160, and the front end portion 175 is linked to an input shaft (not shown) provided in the front axle case via a transmission shaft or the like. It is connected.

  In this way, the rotational power of the auxiliary transmission shaft 116 is output gear 166 attached to the auxiliary transmission shaft 116 → first intermediate gear 167 → second intermediate gear 168 → input gear 165 → front wheel drive shaft 164 → transmission shaft. Etc. → Input shaft → Front axle → Front wheels 7 and 7 so that four-wheel drive traveling can be performed.

  Further, in this embodiment, the input gear 165 is spline-fitted to the middle part of the front wheel drive shaft 164, and can be shifted to a position engaged with the second intermediate gear 168 and a position disengaged. The shift operation of the input gear 165 can be performed from the outside of the extraction unit case 160 by a shift operation mechanism (not shown).

  Thus, when the shift operation for meshing the input gear 165 with the second intermediate gear 168 is performed, the four-wheel drive traveling can be performed as described above, while the shift operation for releasing the meshing of the input gear 165 from the second intermediate gear 168. When this is done, two-wheel drive traveling with only the rear wheel drive can be performed, and switching operation between four-wheel drive traveling and two-wheel drive traveling is appropriately performed according to work conditions so that the work can be performed efficiently.

[Operating part 5]
As shown in FIG. 1, the driving unit 5 has a steering column 280 provided upright at a position behind the prime mover unit 2 and above the clutch unit 3, and an upper end portion of the steering column 280 via a wheel support shaft 281. A steering wheel 282 is attached, a driver's seat 283 is disposed at a rear position of the steering wheel 282, and the main transmission lever 85 and the auxiliary transmission lever 142 are concentratedly disposed at a side position of the driver's seat 283.

[PTO transmission 6]
As shown in FIG. 11, the PTO transmission unit 6 detachably attaches the PTO case 200 to the opening 111 formed at the rear end of the differential case 55 of the transmission case 45, and the PTO transmission unit 200 has a PTO transmission in the PTO case 200. A mechanism 201 is provided.

  Hereinafter, the configurations of the [PTO case 200] and the [PTO speed change mechanism 201] will be described in this order with reference to FIG.

[PTO case 200]
As shown in FIG. 11, the PTO case 200 is divided into a front case forming body 202, an intermediate case forming body 203, and a rear case forming body 204 so that the case forming bodies 202, 203, and 204 are detachable from each other. The front case forming body 202 and the intermediate case forming body 203 are disposed in the differential case 55 so as to be accommodated in the differential case 55, and the rear case forming body 204 is disposed so as to bulge rearward from the differential case 55. ing.

  Then, a hook-shaped attachment piece 205 is integrally formed on the peripheral edge of the front end of the rear case forming body 204, and the attachment piece 205 is brought into contact with the rear end edge portion of the differential case 55 from the rear, and the axis is set in the front-rear direction. It is attached with the mounting bolt 206 directed.

  In this way, since the PTO case 200 is detachably attached to the opening 111 formed at the rear end of the differential case 55, the PTO case 200 is removed from the differential case 55 of the mission case 45. Assembly work and maintenance work of the PTO transmission mechanism 201 accommodated in the PTO case 200 can be easily performed.

  Moreover, since the PTO case 200 is mounted with the front case forming body 202 and the intermediate case forming body 203 accommodated in the differential case 55 of the mission case 45, the mission case 45 can be made smaller (compact). Can be planned.

  The front case forming body 202 is formed with an input shaft protruding opening 207 for receiving the input shaft 230 that is opened in the front-rear direction, and the transmission shaft front receiving portion 208 is positioned above the input shaft protruding opening 207. Is forming.

  A bearing piece 209 for receiving the front end portion of the PTO shaft 232 is provided in the intermediate case forming body 203. The coaxial receiving piece 209 forms a PTO shaft front portion receiving portion 212 that opens in the front-rear direction in the middle portion. ing.

  In this way, since the bearing piece 209 is disposed on the front end face 210 side of the intermediate case forming body 203, the structure of the mold for forming the intermediate case forming body 203 can be simplified, and the same type The cost of the frame can be reduced.

  Moreover, since the front end surface 210 of the intermediate case forming body 203 and the front end surface 211 of the bearing piece 209 are formed flush with each other, the intermediate case forming body 203 can be formed and processed easily and reliably.

  The rear case forming body 204 is formed by opening a PTO shaft protruding opening portion 214 in the front-rear direction, and a transmission shaft rear receiving portion 215 is formed above the PTO shaft protruding opening portion 214.

  An input shaft protrusion 207 formed in the front case forming body 202, a PTO shaft front receiving portion 212 formed in the intermediate case forming body 203, and a PTO shaft protruding opening formed in the rear case forming body 204 214 is formed to communicate with each other on the same axis extending in the front-rear direction.

  Further, the transmission shaft front receiving portion 208 formed on the front case forming body 202 and the transmission shaft rear receiving portion 215 formed on the rear case forming body 204 are arranged to face each other in the front-rear direction.

  Here, a top link bracket 216 for pivotally connecting and connecting the front end portion of the top link 12 is attached to the pivot pieces 345, 345 of the lift arm support 339 described above. From a plate-shaped mounting seat 217 that is attached to the rear surface of the support pieces 345, 345 by mounting bolts 220, and a pair of left and right plate-shaped pivot support / connection pieces 218, 218 that protrudes rearward from the rear surface of the mounting seat 217. Forming. In FIG. 15, reference numeral 219 denotes a connection hole through which the mounting bolt 220 is inserted.

  Further, lift cylinder support shafts 221 and 221 as a lift cylinder mounting portion protrude outwardly on the left and right side walls of the rear case forming body 204, and the lift cylinder support shafts 221 and 221 and the middle portions of the lift arms 350 and 350 are provided. Between the cylinders, lift cylinders 351 and 351 that extend and contract in the vertical direction are interposed. 223 is a lift cylinder connecting pin, and 224 is a lift cylinder pivot connecting piece.

  In this way, a pair of left and right lift cylinders 351 and 351 that extend and contract in the vertical direction are disposed at the left and right side positions of the rear case forming body 204, and the lower ends of the lift cylinders 351 and 351 are connected to the lift cylinder support shafts 221 and 221 through the lift cylinder support shafts 221 and 221, respectively. Since it is supported by the rear case forming body 204, it is easy to make the lift cylinders 351, 351 vertically or substantially vertically arranged, the stroke of each lift cylinder 351, 351 can be reduced, and each lift cylinder 351, 351 can be reduced. The power loss can be reduced.

  In addition, since the lower end portions of the lift cylinders 351 and 351 are supported by the rear case forming body 204 via the lift cylinder support shafts 221 and 221, the lift cylinders 351 and 351 can be firmly supported.

[PTO speed change mechanism 201]
As shown in FIG. 11, the PTO transmission mechanism 201 is provided with an input shaft 230, a transmission shaft 231, and a PTO shaft 232 each having an axis line in the front-rear direction in the PTO case 200.

  That is, the input shaft 230 is rotatably supported via the bearings 233 and 234 at the input shaft protruding opening 207 formed in the front case forming body 202 of the PTO case 200, and the input shaft 230 While projecting forward, an output gear 236 is provided at the rear end.

  Then, the transmission shaft 231 is rotated via the bearings 237 and 238 between the transmission shaft front receiving portion 208 formed on the front case forming body 202 and the transmission shaft rear receiving portion 215 formed on the rear case forming body 204. A large-diameter input gear 239, a second transmission gear 240, and a first transmission gear 241 are coaxially integrally formed on the same transmission shaft 231 sequentially from the front to the rear so that a large-diameter input is achieved. A gear 239 is meshed with an output gear 236 provided on the input shaft 230.

  In addition, the PTO shaft 232 is rotated between the PTO shaft front receiving portion 212 formed on the intermediate case forming body 203 and the PTO shaft projecting opening 214 formed on the rear case forming body 204 via bearings 242 and 243. It is supported freely.

  In addition, the shift gear body 244 is spline-fitted to the PTO shaft 232 so as to be slidably shifted in the axial direction, and the input gear 267 is rotatably mounted. The shift gear body 244 is provided with a large-diameter shift gear 268 and a small-diameter shift gear 269. On the other hand, an insertion meshing gear 270 is formed on the front surface of the input gear 267 to be engaged with the small-diameter shift gear 269.

  Further, the shift gear body 244 is operated by the PTO speed change operation mechanism 272, the second PTO speed change operation for engaging the large diameter shift gear 268 with the second speed change gear 240, and the first PTO speed change operation for engaging and engaging the small diameter shift gear 269 with the engagement mesh gear 270. Operation.

  The PTO shaft 232 has a distal end portion (rear end portion) 273 projecting rearward from a PTO shaft projecting opening 214 formed in the rear case forming body 204.

  Thus, in the present embodiment, the front case forming body 202 supports the input shaft 230, and the transmission shaft 231 is supported between the front case forming body 202 and the rear case forming body 204, and the intermediate portion Since the PTO shaft 232 is supported between the case forming body 203 and the rear case forming body 204, the degree of freedom of the arrangement of these shafts 230, 231 and 232 is increased, and the shafts can be arranged compactly. The gears 230, 231 and 232 can be engaged and connected easily and reliably.

  Further, since the PTO case 200 is divided into three parts, ie, the front case forming body 202, the intermediate case forming body 203, and the rear case forming body 204, the large diameter input gear 239, the second transmission gear 240, and the first The transmission gear 241 can be easily assembled between the front case forming body 202 and the rear case forming body 204 via the transmission shaft 231, and the transmission shaft 231 and the gears 239, 240, 241 can be easily and reliably arranged. Therefore, the assembly work efficiency of the PTO transmission mechanism 201 can be improved.

  A clutch mechanism 275 is provided on the PTO shaft 232, and the clutch mechanism 275 is connected / disconnected by the clutch operating mechanism 276.

  Further, as shown in FIG. 4, the tip end portion 235 of the input shaft 230 is linked to the outer drive shaft 20 via a PTO transmission shaft 169 to form a PTO transmission mechanism 52, and the PTO transmission The shaft 169 is disposed in the mission case 45 with its axis line in the front-rear direction from the front to the rear.

(PTO transmission shaft 169)
As shown in FIG. 4, the PTO transmission shaft 169 is formed by connecting the first to fourth divided transmission shafts 245, 246, 247, 248 in the front-rear direction.

  As shown in FIGS. 4 and 6, the first split transmission shaft 245 is rotatably mounted between the rear wall 27 of the clutch housing 17 and the internal support wall 57 via bearings 249 and 250. An input gear 244 is provided in the middle of the first split transmission shaft 245, and the input gear 244 is meshed with the PTO drive gear 20c.

  Further, as shown in FIG. 4, the second split transmission shaft 246 supports the shaft support wall forming body 50 through a bearing 251 so as to be able to rotate the midway portion, and the front end portion is the first split transmission shaft. The rear end portion of 245 is connected via a first cylindrical connecting body 252.

  As shown in FIGS. 4 and 9, the third split transmission shaft 247 is supported by a shaft support 118 via a bearing 253 so as to be able to rotate the middle portion, and the front end portion of the second split transmission shaft 246 is supported. The rear end portion is connected via a second cylindrical connecting body 254.

  As shown in FIGS. 4 and 11, the fourth split transmission shaft 248 has a front end connected to the rear end of the third split transmission shaft 247 via a one-way clutch 255, and a rear end connected to the input shaft. The tip end portion 235 of 230 is connected via a third cylindrical connecting body 256.

  Here, the one-way clutch 255 is formed of a front clutch forming body 257 attached to the rear end portion of the third split transmission shaft 247 and a rear clutch forming body 258 attached to the front end portion of the fourth split transmission shaft 248. The meshing piece 259 projecting on the rear surface of the front clutch forming body 257 and the meshing piece 260 projecting on the front surface of the rear clutch forming body 258 are meshed in the front-rear facing state, and both meshing pieces are used in the forward rotation. The third and fourth divided transmission shafts 247 and 248 are integrally rotated in the forward rotation direction while the 259 and 260 are engaged with each other, while the meshing pieces 259 and 260 are not engaged in the reverse rotation.

  In this way, the power transmitted from the engine 15 to the outer drive shaft 20 is the PTO drive gear 20c integrally formed on the outer drive shaft 20, the input gear 244, the first divided transmission shaft 245, and the first cylindrical connecting body. 252 → second divided transmission shaft 246 → second cylindrical connecting body 254 → third divided transmission shaft 247 → one-way clutch 255 → fourth divided transmission shaft 248 → third cylindrical connecting body 256 → input shaft 230 I am doing so.

  When the first PTO speed change mechanism 201 is operated, the power transmitted to the input shaft 230 is output gear 236 → large diameter input gear 239 → speed change shaft 231 → first speed change gear 240 → shift gear body. The 244 large-diameter shift gear 268 is transmitted to the PTO shaft 232, and power can be extracted from the PTO shaft 232 to drive various working machines.

  Further, when the PTO transmission mechanism 201 is operated for the second PTO transmission, the power transmitted to the input shaft 230 is output gear 236 → large diameter input gear 239 → transmission shaft 231 → second transmission gear 241 → input gear. 267 → insertion meshing gear 270 of the input gear 267 → small-diameter shift gear 269 of the shift gear body 244 → transmission to the PTO shaft 232, and power can be taken out from the PTO shaft 232 to drive various working machines. .

  At this time, even if the PTO shaft 232 is reversely rotated in response to loads from various work machines and the power is transmitted from the input shaft 230 to the third cylindrical connecting body 256 to the fourth divided transmission shaft 248, Since the one-way clutch 255 is interposed between the four-divided transmission shaft 248 and the third divided transmission shaft 247, no power is transmitted from the fourth divided transmission shaft 248 to the third divided transmission shaft 247.

  Therefore, the power is transmitted from the PTO shaft 232 back to the traveling system transmission mechanism 51 including the main transmission mechanism 46 to prevent the traveling system transmission mechanism 51 from being damaged. Can do.

  19 and 20 show lift arms 350 and 350 as other embodiments. The lift arms 350 and 350 are integrally formed with a base end portion via a rotation boss portion 430, and the rotation boss portion is the same. 430 is fitted between the pair of left and right pivot pieces 345 and 345 in the center of the lift arm support shaft 344, and the pair of left and right lift arms 350 and 350 are rotated about the lift arm support shaft 344 via the rotating boss portion 430. It is made to rotate integrally.

  In this way, since the pair of left and right lift arms 350, 350 are integrally formed via the rotating boss portion 430, the mounting work of both lift arms 350, 350 can be performed easily.

  FIG. 21 shows a branch position temporary fixing portion 314 as another embodiment, and the branch position temporary fixing portion 314 is provided with an adjustment male screw body 431 as a temporary fixing strength adjusting portion.

  That is, the adjustment male screw body 431 is formed in a bar shape by extending in the vertical direction, and has a male screw portion 432 on the outer peripheral surface, and is formed on the left side of the ceiling portion 315 of the cover body 302 in the vertical direction. The ball receiving vertical hole 316 is formed so as to pass through, and a female screw part 433 is formed on the upper inner peripheral surface of the ball receiving vertical hole 316, and the adjusting male screw body 431 is screwed into the female screw part 433. A pressing spring 318 is interposed between the lower end of the adjusting male screw body 431 and the temporary fixing ball 319.

  The adjustment male screw body 431 is formed so as to protrude from the cover main body 302 in substantially the same axial direction as the main / sub transmission levers 85 and 142, and an adjustment rubbing piece 434 is provided at the tip (upper end). Reference numeral 435 denotes a fixing nut.

  In this way, the pressing force applied to the temporary fixing ball 319 of the pressing spring 318 is appropriately adjusted by holding the adjustment rubbing piece 434 and turning the adjustment male screw body 431, and temporarily fixed by the temporary fixing ball 319. The strength can be adjusted.

  Therefore, the operator can feel the response according to his / her preference, and the operability of the main speed change lever 85 can be improved.

  At this time, unlike the shift position temporary fixing portion 323, the branch position temporary fixing portion 314 does not serve to prevent gear disengagement during power transmission, so there is no need to maintain the temporary fixing force above a certain level. The temporary fixing strength can be adjusted freely so that a response according to the user's preference can be obtained.

  In addition, since the adjustment squeeze piece 434 is formed so as to protrude in substantially the same axial direction as the main and sub transmission levers 85 and 142, the operator can easily squeeze the adjustment squeeze piece 434 from above and the same. The temporary fixing adjustment by the adjustment rubbing piece 434 can be performed smoothly and reliably.

The side view of the tractor concerning the present invention. The side view of a clutch part and a mission part. The top view of a clutch part and a mission part. Sectional side explanatory drawing of the clutch part and a mission part. A partially cutaway rear view of the mission section. Sectional side explanatory drawing of the clutch part. Sectional side explanatory drawing of a main transmission part. The rear view of a main transmission part. Cross-sectional side explanatory drawing of a subtransmission part. The expanded cross-section back explanatory drawing of the upper part of the subtransmission part. Cross-sectional side explanatory drawing of a differential mechanism and a PTO transmission part. Sectional back surface explanatory drawing of a differential mechanism. The partially cutaway side view of the lift arm support. The top view of the lift arm support body. The partially cutaway rear view of the lift arm support body. Cross-sectional plan explanatory drawing of a hydraulic circuit body. The center part cross section side view of the hydraulic circuit body. The left part cross-section side view of the hydraulic circuit body. The top view of the lift arm support body as other embodiment. The partially cutaway rear view of the lift arm support body. The expanded sectional side view of the branch position temporary fix | stop part as other embodiment.

Explanation of symbols

A Tractor 1 Airframe frame 2 Motor part 3 Clutch part 4 Mission part 5 Driving part 6 PTO transmission part
45 mission case
46 Main transmission mechanism
47 Sub-transmission mechanism
53 Main transmission case
54 Sub-shift case
73b shift fork
81 Lever interlocking shaft
85 Main transmission lever
142 Sub-shift lever
301 Lever base cover body
314 Temporary stop at branch position
339 Lift arm support
340 Hydraulic circuit body support piece
341 Hydraulic circuit body
342 Hydraulic control valve
344 Lift arm spindle
350 Lift arm
351 lift cylinder
352 Grease nipple
385 Tank side return vertical oil passage
387 Valve cover body
431 Male screw body for adjustment S Drain receiving space

Claims (1)

A lift arm (350, 350) is attached to the upper part of the transmission case (45) via a lift arm support (339), and the lift arm (350, 350) is a hydraulic pressure detachably attached to the lift arm support (339). Hydraulic control is possible with hydraulic control valve (342) via circuit body (341),
The valve cover body (387) is attached to the hydraulic circuit body (341), the hydraulic control valve (342) is accommodated in the valve cover body (387), and the drain of the hydraulic control valve (342) is connected to the valve cover. It is possible to discharge through the drain circuit formed in the hydraulic circuit body (341) through the drain receiving space (S) formed in the body (387) ,
The hydraulic circuit body (341) is detachably attached to the transmission case (45) via the lift arm support body (339), and the upper surface opening box type valve cover body (387) is provided below the hydraulic circuit body (341). A tractor (A) in which the upper end edge of the valve cover (387) is attached in a sealed state and the lower part of the valve cover body (387) is disposed in the transmission case (45),
The lift arm support (339) includes a ring-shaped attachment piece (343) for attaching to the periphery of the opening (106) formed in the ceiling portion of the differential case (55), and the attachment piece ( 343) is raised upward at the front of the cylindrical hydraulic circuit body support piece (340) for supporting the hydraulic circuit body (341), and is lifted up at the rear of the attachment piece (343) to support the lift arm. A pair of left and right pivot pieces (345, 345) pivotally supporting the shaft (344),
Attach the base end of the pair of left and right lift arms (350, 350) to the lift arm spindle (344), and expand and contract vertically between the middle of each lift arm (350, 350) and the lower part of the differential case (55). The lift arm (350, 350) can be moved up and down by both lift cylinders (351, 351) through a lift cylinder (351, 351) .

Images