JP4242755B2 - Tractor - Google Patents

Description

  The present invention relates to a tractor.

Conventionally, as one form of the tractor, an engine is provided at the front part of the body frame, a driving part is provided at a rear position of the engine, a transmission case is provided at a position below a driver's seat provided in the driving part, and the transmission case is provided. There is a PTO transmission mechanism provided therein, and a PTO shaft interlockingly connected to the PTO transmission mechanism is protruded rearward from the rear wall of the transmission case (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 7-232570

  However, in the tractor described above, since the PTO transmission mechanism is provided in the transmission case, assembly work and maintenance work of the PTO transmission mechanism must be performed in the transmission case, which requires time and effort. In addition to the problems, the mission case itself is lengthened backwards.

Therefore, in the present invention, a PTO case having a built-in PTO transmission mechanism is detachably attached in the transmission case so that at least the front part is accommodated, and the PTO case includes a front case forming body and an intermediate case. A tractor formed in three parts on a forming body and a rear case forming body, wherein the input shaft is supported by the front case forming body, and the transmission shaft is supported by the front case forming body and the rear case forming body. The present invention provides a tractor characterized in that the PTO shaft is supported by the forming body and the rear case forming body, and the gear stage specifications can be changed by changing the intermediate case forming body and the transmission shaft .

In the present invention, a PTO case having a built-in PTO speed change mechanism is detachably attached in a transmission case so that at least the front part is accommodated, and the PTO case includes a front case forming body and an intermediate case forming body. The rear case forming body is divided into three parts.

  In this way, since the PTO case incorporating the PTO transmission mechanism is detachably attached to the rear part of the transmission case, the PTO transmission mechanism incorporated in the PTO case is removed with the PTO case removed from the transmission case. Assembly work and maintenance work can be easily performed.

  In addition, since the PTO case is attached with at least the front portion accommodated in the mission case, the mission case can be reduced in size (compact).

  Furthermore, since the PTO case is divided into three parts, a front case forming body, an intermediate case forming body, and a rear case forming body, a PTO transmission mechanism is assembled by disposing a shaft and gears in the PTO case. Work can be done easily.

  For example, since a single shaft and a plurality of gears can be integrally formed and assembled between required case forming bodies, such gears can be easily and reliably disposed, and the PTO transmission mechanism Assembly work efficiency can be improved.

In the present invention, the input shaft is supported by the front case forming body, the transmission shaft is supported by the front case forming body and the rear case forming body, and the PTO shaft is supported by the intermediate case forming body and the rear case forming body. Is supported.

  In this way, since the shaft is arranged between each case-formed body or the case-formed bodies divided into three, the degree of freedom of the arrangement of the shaft is increased, and it can be arranged compactly, The gears provided on each shaft can be easily and reliably engaged and connected.

In addition, in the present invention, the gear stage specification can be changed by changing the intermediate case forming body and the transmission shaft.

  In this way, the gear stage specification can be changed simply by changing the intermediate case forming body, and thus the gear stage specification can be changed easily and reliably in a short time.

  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. 9). . 10 is a front guard frame, 11 is a rear guard frame, 12 is a top link for connecting work machines, 13 is a lower link for connecting work machines, and 14 is a work machine connecting piece.

  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.

  As shown in FIGS. 2 to 4, 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 body 18 is formed of an inner drive shaft 19 that extends 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.

  The inner drive shaft 19 is 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, a cylindrical support body. 28 is disposed in the rear portion 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.

  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 of the connection, the prior art, that is, the distal end portion of the inner drive shaft is extended to the rear position from the distal end portion of the outer drive shaft, and the base end of the PTO input shaft is connected through a cylindrical shaft joint. The clutch housing 17 and the main transmission case 53 are connected in the front-rear direction compared to the conventional technology in which the two are connected to each other on the same axis and in the clutch housing 17 and the main transmission case 53. Even when the inner and outer double drive shafts 18 are 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.

  As shown in FIGS. 2 and 3, 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. The creep transmission unit 49 is detachably attached to the transmission case 45, and the creep transmission mechanism 50 provided in the creep transmission unit 49 is interlocked with the auxiliary transmission mechanism 47 so that the main transmission, A traveling transmission mechanism 51 that can perform sub-shifting and further creep shifting is formed, and a PTO transmission mechanism 52 is interposed between the outer drive shaft 20 and a PTO transmission 6 described later.

  The transmission case 45 is divided into a main transmission case 53 containing the main transmission mechanism 46 and a case main body 54 containing the auxiliary transmission mechanism 47 and the differential mechanism 48. The main transmission case 53 is The front end edge of the clutch housing 17 is detachably connected to the rear end edge of the clutch housing 17 by a connecting bolt 56a, and the case main body 54 is connected to the rear end edge of the main transmission case 53 via the support wall forming body 55. The edges are detachably connected by a connecting bolt 56b.

  Therefore, for convenience of explanation, the configuration of the PTO transmission unit 6 according to the present invention will be described first, and then the PTO transmission shaft 169, the main transmission case 53, the main transmission mechanism 46, the case main body 54, the auxiliary transmission mechanism. Each configuration of 47 and the differential mechanism 48 will be described in this order.

  That is, as shown in FIG. 8, the PTO transmission unit 6 detachably attaches the PTO case 200 to the opening 111 formed at the rear end of the case body 54 of the mission case 45, and the PTO case 200 is placed in the PTO case 200. A PTO transmission mechanism 201 is provided.

  Hereinafter, the components of the PTO case 200 and the PTO transmission mechanism 201 will be described in this order with reference to FIGS. 8 and 12 to 16.

[PTO case]
As shown in FIGS. 8 and 12 to 15, the PTO case 200 is divided into three parts, a front case forming body 202, an intermediate case forming body 203, and a rear case forming body 204, and the case forming bodies 202, 203, 204 are connected to each other. The front case forming body 202 and the intermediate case forming body 203 are disposed in the housing state in the case main body 54, and the rear case forming body 204 is moved rearward from the case main body 54. Arranged in a bulging state. 225 is a front / intermediate positioning knock for determining the connection position between the front case forming body 202 and the intermediate case forming body 203, and 226 is a connection between the intermediate case forming body 203 and the rear case forming body 204. An intermediate / rear positioning knock 227 for determining the connecting position is an intermediate / rear connecting bolt for connecting the intermediate case forming body 203 and the rear case forming body 204.

  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 of the case main body 54 from the rear, and the axis in the front-rear direction is provided. It is attached with the mounting bolt 206 directed.

  In this manner, since the PTO case 200 is detachably attached to the opening 111 formed at the rear end of the case main body 54, the PTO case 200 is removed with the PTO case 200 removed from the transmission case 45. Assembling work and maintenance work of the PTO transmission mechanism 201 accommodated in the housing 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 case body 54 of the mission case 45, the mission case 45 can be reduced in size (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, and the coaxial receiving piece 209 is disposed on the front end face 210 side of the intermediate case forming body 203, and the front side The end surface 210 and the front end surface 211 of the bearing piece 209 are formed flush with each other, and a PTO shaft front receiving portion 212 that opens in the front-rear direction is formed in the middle portion. Reference numeral 213 denotes a virtual coplanar surface.

  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 between the rear portion of the lift arm support 108 and the upper portion of the rear end edge portion of the case body 54. The top link bracket 216 includes a plate-shaped mounting seat 217 that is attached to the rear portion of the lift arm support 108 and the upper portion of the rear end edge portion of the case main body 54 by a mounting bolt 220, and the rear surface of the mounting seat 217. It is formed from a pair of left and right plate-like pivot / connecting pieces 218 and 218 that project more rearward. Reference numeral 219 denotes a connecting hole.

  Then, the lower part of the mounting seat 217 is brought into contact with the mounting piece 205 of the rear case forming body 204 from the rear to be in a superposed state, and is fastened together with the mounting bolt 206 and attached to the rear edge of the case main body 54. Yes.

  Further, lift cylinder support shafts 221 and 221 as a lift cylinder mounting portion project outward from 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 120 and 120 are provided. There are interposed lift cylinders 222 and 222 that extend and contract in the vertical direction. 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 222, 222 that extend and contract in the vertical direction are arranged at the left and right side positions of the rear case forming body 204, and the lower ends of the lift cylinders 222, 222 are arranged via the lift cylinder support shafts 221, 221. Since it is supported by the rear case forming body 204, it is easy to make the lift cylinders 222, 222 vertically or substantially vertically arranged, the stroke of each lift cylinder 222, 222 can be reduced, and each lift cylinder 222, 222 can be reduced. The power loss can be reduced.

  Moreover, since the lower end portions of the lift cylinders 222 and 222 are supported by the rear case forming body 204 via the lift cylinder support shafts 221 and 221, the lift cylinders 222 and 222 can be firmly supported.

  Further, for example, the left and right width of the rear case forming body 204 is reduced, and the pair of left and right lift cylinders 222, 222 are disposed at the left and right lateral positions of the rear case forming body 204 and are disposed within the left and right width of the case main body 54. As a result, the degree of freedom of the attachment position of the elevating link mechanism to the case body 54 can be increased.

[PTO transmission mechanism]
Next, the PTO speed change mechanism 201 will be described. The PTO speed change mechanism 201 includes an input shaft 230 having an axis line in the front-rear direction in the PTO case 200, as shown in FIGS. A transmission shaft 231 and a PTO shaft 232 are disposed.

  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 first transmission gear 240, and a second 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 shiftable in the axial direction, and the input gear 267 is rotatably mounted via the bearings 265 and 266. While the small-diameter shift gear 269 is provided, a fitting mesh gear 270 is formed on the front surface of the input gear 267 so that the small-diameter shift gear 269 is fitted and meshed therewith.

  Further, a first PTO speed change operation in which the shift gear body 244 is engaged with the first speed change gear 240 by the PTO speed change operation mechanism 272, and a second PTO speed change operation in which the small diameter shift gear 269 is engaged and engaged 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.

  Furthermore, 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 first transmission gear 240, and the second The transmission gear 241 and the transmission shaft 231 are integrally formed, and the transmission shaft 231 can be easily assembled between the front case forming body 202 and the rear case forming body 204. 239, 240, 241 can be easily and reliably arranged, and the assembly work efficiency of the PTO transmission mechanism 201 can be improved.

  Further, the PTO transmission unit 6 shown in FIG. 12 is a two-speed transmission specification, and the PTO transmission unit 6 shown in FIG. 16 is a one-speed transmission specification, which can be simplified by replacing the intermediate case forming body 203 and the transmission shaft 231. The gear specifications can be changed.

  That is, the transmission shaft 231 of the one-speed transmission specification is formed by integrally forming the large-diameter input gear 239 and the transmission gear 274 on the transmission shaft 231 and shortening the front-rear length of the transmission shaft 231. The case forming body 203 is shortened in the front-rear width by adapting to the front-rear width of the shortened transmission shaft 231.

  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. Reference numeral 277 denotes a meshing gear provided in the clutch mechanism 275.

  In this way, the gear stage specification can be changed simply by replacing the intermediate case forming body 203 and the transmission shaft 231. Therefore, the change of the gear stage specification can be performed easily and reliably in a short time.

  Further, as shown in FIG. 3, 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 constitute a PTO transmission mechanism 52. 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]
That is, 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 FIG.

  As shown in FIGS. 3 and 5, 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 FIGS. 3 and 5, the second split transmission shaft 246 is supported by the support wall forming body 55 via a bearing 251 so as to be able to turn the midway portion, and the front end portion is the first split portion. The rear end portion of the transmission shaft 245 is connected via a first cylindrical connecting body 252.

  As shown in FIGS. 3 and 8, the third split transmission shaft 247 is supported by a shaft support 118 via a bearing 253 so as to be able to turn the midway 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. 3 and 8, the fourth split transmission shaft 248 has a front end connected to a 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.

[Main transmission case]
As shown in FIGS. 5 and 6, the main transmission case 53 is formed in a cylindrical shape extending in the front-rear direction, and an internal support wall 57 is formed on the front inner peripheral surface, and the internal support wall 57 and the support wall A main speed change mechanism 46 is interposed between the formed body 55 and the main speed change mechanism 46 can perform a plurality of steps (five steps in this embodiment) of forward shift operation and reverse switching operation.

[Main transmission mechanism]
As shown in FIGS. 5 and 6, 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 support wall forming body 55 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 a gap 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.

  A main transmission countershaft 70 extending in the front-rear direction is supported between the inner support wall 57 and the support wall forming body 55 via front and rear bearings 68 and 69, and the main transmission subshaft is supported. First, second, and third transmission gear bodies 71, 72, and 73 are coaxially and rotatably attached to the outer peripheral surface of 70.

  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 60, 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 formed integrally with the third transmission gear body 73 is meshed with the reverse switching gear 64 via a counter gear 74 pivotally supported by the support wall forming body 55. 75 is a counter gear support shaft, and 76 is a shaft support provided in the main transmission case 53.

  Further, as shown in FIGS. 5 to 7, a slide body support shaft 80 extending in the front-rear direction is provided between the internal support wall 57 and the support wall forming body 55, just above the main transmission main shaft 58. The lever interlocking shaft 81 extending in the front-rear direction and extending in the front-rear direction is installed parallel to the right side position of the slide body support shaft 80 so as to be slidable back and forth. The front end of the engaging piece 82 projecting leftward from the front part is engaged with the engaged piece 83 provided at the front part of the slide body support shaft 80, while the lever is extended into the case main body 54. An action receiving piece 84 is provided at the rear end of the interlocking shaft 81, and an action piece 85a formed at the lower end of the main transmission lever 85 is engaged with the action receiving piece 84. 97 is an action receiving piece mounting pin.

  As shown in FIG. 2, a swing support body 86 is provided on the ceiling portion 54c of the case body 54, and as shown in FIG. 6, a swing support piece 87 provided on the swing support body 86 is arranged in the vertical direction. The lower part of the extending main transmission lever 85 is pivotally supported so that the main transmission lever 85 can be swung freely in the front-rear and left-right directions. The lower end of the operating piece 85a formed at the lower end of the main transmission lever 85 is It is inserted into the lever insertion hole 88 formed in the portion 54c and engaged with the action receiving piece 84. 89 is a lever neutral return spring.

  Further, as shown in FIGS. 5 and 7, 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, A slide action piece 92 is projected from the slide body support 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 receiving piece 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 case main body 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 third transmission gear body 71 → Main transmission subshaft 70 → front gear 73a of first 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 formation pieces 91a and 91b of the slide restricting body 91 are formed on 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 → engagement piece 82 → engaged piece 83 → slide body support shaft 80, and the slide body support 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 third 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 formation piece 91b of the slide restricting body 91 is the slide action of 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 to rotate the sliding body supporting shaft 80 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 third transmission gear body 71. The transmission is transmitted from the fourth speed gear 62 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 of the third transmission body 65, and the fourth speed change is performed.

  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 defining piece 91a of the slide restriction body 91 is slid on the first and second slide bodies 95 and 94. Engagement with the action receiving pieces 95c, 94c restricts the movement of both slide bodies 95, 94.

(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 third slide body 95 → the boss portion 95a → the shift fork 95b, and is transmitted to the shift fork 95b. The slide connecting piece 67d of the third transmission body 67 that is interlocked and connected is slid from the neutral position to the forward slide speed changing position, and the shaft side interlocking connecting piece 67a and the front gear side interlocking connecting piece 67b 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 31 c → the front gear side interlocking connection piece of the third transmission 67. 65b → slide connecting piece 67d → 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 defining piece 91a of the slide restriction body 91 is slid on the first and second slide bodies 95 and 94. Engagement with the action receiving pieces 95c, 94c restricts the movement of both slide bodies 95, 94.

(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 connection piece 67d of the third transmission body 67 that is interlocked and connected is slid from the neutral position to the rear slide speed change position, so that the shaft side interlocking connection piece 67a and the rear gear side interlocking connection 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 third transmission gear body 71 → Main transmission subshaft 70 → rear gear 73b of first transmission gear body 73 → counter gear 74 → reverse switching gear 64 → rear gear side interlocking connection piece 67c of third transmission body 67 → slide connection piece 67d → shaft 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 formation pieces 91a and 91b of the slide restricting body 91 are formed on 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.

[Case body]
As shown in FIGS. 2, 8, and 11, the case main body 54 is formed in a cylindrical shape extending in the front-rear direction, and the shaft support wall 100 is formed in the middle of the inner peripheral surface. The sub-transmission mechanism 47 is disposed at the front position of the shaft support wall 100, and the differential mechanism 48 is disposed at the rear position of the coaxial support wall 100.

  And, in the case main body 54 located in front of the shaft support wall 100, an opening 101 is formed in the right side wall 54b, and a creep transmission unit 49 described later is detachably attached through the opening 101, An opening 102 is formed in the bottom 54d, and a front wheel drive power take-out portion 103, which will be described later, is attached through the opening 102. The creep transmission portion 49 and the front wheel drive power take-out portion 103 are respectively connected to the sub-wheel drive power take-out portion 103. The transmission mechanism 47 is interlocked and connected.

  Further, as shown in FIG. 9, openings 104 and 104 are formed in the left and right side walls 54a and 54b, respectively, in the case main body 54 located behind the shaft support wall 100, and the rear axle case 8 is passed through the openings 104 and 104. , 8 are connected to each other, and the 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 connected to the differential mechanism 48 in an interlocking manner. Yes.

  In addition, as shown in FIG. 8, the case body 54 located behind the shaft support wall 100 is formed with a maintenance opening 106 in the ceiling, and the opening 106 can be attached to and detached from the lid 107. The lift arm support 108 is formed to bulge upward at the rear part of the cover 107, and the lift arm support with the axis line directed in the left-right direction on the upper part of the lift arm support 108. The shaft 109 is inserted and supported so as to be rotatable, and the base ends of a pair of left and right lift arms 110 and 110 are attached to the left and right ends of the lift arm support shaft 109.

  Furthermore, as shown in FIG. 8, the PTO transmission 6 is attached to the opening 111 formed at the rear end of the case main body 54.

  Further, as shown in FIGS. 2 and 8, lower link connecting pins 112, 112 project outward from the rear lower portions of the left and right side walls of the case body 54, and the front ends of the pair of left and right lower links 13, 13 are provided. The case body 54 is rotatably supported by the lower link connecting pins 112, 112.

[Sub-transmission mechanism]
As shown in FIG. 8, the sub-transmission mechanism 47 is constructed by interlockingly connecting a sub-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 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 and has a midway portion. A shaft support 118 provided in the case main body 54 is supported via a bearing 119, and a front end portion (rear end portion) is supported by the shaft support wall 100 via a bearing 120.

  The planetary gear mechanism 115 is formed by attaching 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 to the support wall forming body 55 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. While meshing with both of the sun gears 117, a carrier 128 is attached via a pair of front and rear bearings 126 and 127 between the inner peripheral edges of a pair of front and rear inner gear supports 121 and 122, and a plurality of planetary gears 125 are integrally linked to the carrier 128. Concatenated.

  In addition, the carrier 128 has a rear end edge extending rearward from the rear bearing 127 to form a cylindrical gear forming piece 129, and the inner teeth 130 are formed on the inner peripheral surface of the gear forming piece 129. And external teeth 131 as creep drive gears are formed on the outer 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. The front shift gear 133 is integrally formed on the front outer peripheral surface of the shift gear support 132, and the rear shift gear 134 is integrally formed on the rear outer peripheral surface.

  As shown in FIGS. 10 and 11, a fork support shaft 135 having an axial line in the front-rear direction is disposed on the right side in the case main body 54, and the base of the shift fork 136 is disposed on the fork support shaft 135. The end 137 is attached so as to be slidable back and forth, and the front end 138 of the shift fork 136 is engaged with the shift gear support 132.

  In addition, a boss portion 140 having an axis line in the left-right direction is formed on a lid body 139 that constitutes a part of a creep transmission portion 49, which will be described later, and a lever support shaft 141 is inserted into the boss portion 140 so as to support the lever support. The base end of the auxiliary transmission lever 142 is attached to the outer end of the shaft 141, the base end of the interlocking arm 143 is attached to the inner end of the lever support shaft 141, and the top 144 is attached to the tip of the interlocking arm 143. The base end portion 137 of the shift fork 136 is connected via the via.

  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 lever support shaft 141, and the shift fork 136 connected to the tip of the interlocking arm 143 via the top 144 is provided. The shift gear support 132 that is slid forward and 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 lever support shaft 141, and the shift fork 136 connected to the tip of the interlocking arm 143 via the top 144 is provided. The shift gear support 132 that is slid rearward and 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.

  Further, in this embodiment, when the auxiliary transmission lever 142 is further rotated forward, the creep transmission unit 49 performs a creep transmission (ultra-low speed transmission).

  Here, the creep transmission unit 49 will be described. As shown in FIGS. 8, 10 and 11, the creep transmission unit 49 has a lid 139 in an opening 101 formed in the right side wall of the case body 54. As shown in FIG. The lid 139 is detachably attached by a mounting bolt 145, and the creep transmission mechanism 146 is detachably attached to the inner surface of the lid 139.

  The creep transmission mechanism 146 detachably mounts a gear support shaft 149 having an axial line in the front-rear direction between a pair of front and rear shaft support pieces 147, 148 protruding from the inner surface of the lid 139. A creep transmission gear body 151 is rotatably attached via a bearing 150, and a large-diameter input gear 152 and a small-diameter output gear 153 are integrally formed at the front and rear portions of the creep transmission gear body 151. .

  In addition, the input gear 152 is detachably engaged with an external tooth 131 as a creep drive gear formed on the outer peripheral surface of the gear forming piece 129, and the output gear 153 is rotatable on the auxiliary transmission shaft 116 via a bearing 154. The creep transmission gear 155 attached to the detachable gear is detachably engaged, and the front shift gear 155 is fitted with the rear shift gear 134 integrally formed on the outer peripheral surface of the rear portion of the shift gear support 132 so as to be engaged. 156 is formed.

  In this way, when the auxiliary transmission lever 142 is rotated forward as much as possible, the interlocking arm 143 is rotated backward via the lever support shaft 141, and the tip of the interlocking arm 143 is connected via the top 144. The connected shift fork 136 is slid rearward, and the shift gear support 132 engaged with the shift fork 136 is shifted rearward as much as possible.

  The shift gear support 132 is detached from the outer peripheral surface of the sun gear 117 and shifted onto the outer peripheral surface of the base end portion (front end portion) 114 of the auxiliary transmission shaft 116, and the rear shift gear 134 is connected to the creep transmission gear 155. It is engaged with an engagement mesh gear 156 formed on the front 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. Tooth 131 → Input gear 152 of creep transmission gear body 151 → Output gear 153 of creep transmission gear body 151 → Creep transmission gear 155 → Fitting gear 156 → Rear shift gear 134 integrally molded on the rear outer peripheral surface of shift gear support 132 → Shift gear It is transmitted from the support body 132 to the base end portion 114 of the auxiliary transmission shaft 116.

  At this time, the power that has been decelerated to ultra-low speed is transmitted from the main speed change main shaft 58 to the sub speed change shaft 116 via the planetary gear mechanism 115 and the creep speed change mechanism 146, and the creep speed change is performed.

  Here, since the input gear 152 of the creep transmission gear body 151 is detachably engaged with the external teeth 131 of the gear forming piece 129 integrally formed as a creep drive gear with the carrier 128, the creep transmission mechanism 146 is replaced with the planetary gear mechanism. The peripheral portion of 115 can be arranged in a compact manner, and an increase in the length of the mission unit 4 can be avoided.

  In addition, since the creep shift operation can be performed linearly in the axial direction of the planetary gear mechanism 115, the shift operation mechanism can be simplified.

  Further, the creep transmission mechanism 146 is attached to the lid body 139 to form the creep transmission section 49, and the creep transmission section 49 is detachably attached to the opening 101 formed in the case body 54 and closed. Since the cover is covered, the assemblability of the creep transmission unit 49 can be improved.

  If the creep specification is not required, the creep transmission mechanism 146 is removed from the lid body 139, and the lid body 139 is attached to the opening 101 of the case body 54, so that the creep condition is applied. Specification can be easily changed to none.

  If creep specifications are required, the creep transmission mechanism 146 may be attached to the lid body 139, and the specification setting with and without creep can be easily performed.

  As shown in FIGS. 2 and 8, the front wheel drive power take-out portion 103 is attached to the opening portion 102 formed in the bottom portion of the case main body 54 with the attaching bolt 161 by the mounting bolt 161. A front wheel drive shaft 164 whose axis is directed in the front-rear direction via a pair of front and rear bearings 162, 163 is installed, and an input gear 165 is attached to the middle portion of the front wheel drive shaft 164. First and second intermediate gears 167 and 168 are interposed between an output gear 166 attached to the rear portion of 116.

  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 gears formed to protrude into the case body 54. A gear support shaft 173 is installed on the 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 shaft 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.

[Differential mechanism]
As shown in FIGS. 8 and 9, 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 is provided with a large reduction gear 183 that meshes with the output bevel gear 180 on the outer peripheral surface of the differential case 182 and a small differential gear support shaft 184 that extends in the front-rear direction in the differential case 182. A pair of front and rear small differential gears 185 and 185 are rotatably attached, and a pair of left and right large differential gear shafts 186 and 186 are attached to the left and right pair of large differential gears 187 and 187, respectively. The moving gears 187 and 187 are meshed with the small differential gears 185 and 185, respectively.

  The cylindrical communication connecting pieces 188, 188 integrally formed on the left and right side portions of the differential case 182 can be connected to each other by detachably fitting a pair of left and right cylindrical shaft supports 189, 189 with the axis line in the left-right direction. None, the large differential gear support shafts 186, 186 are inserted into and supported by the respective cylindrical shaft support members 189, 189 through the respective cylindrical communication connecting pieces 188, 188, and the cylindrical shafts of the respective 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 portions that protrude from the support bodies 189 and 189, respectively, and the front ends of the large differential gear support shafts 186 and 186 are brakes for running brake units 191 and 191 described later, respectively. Removably connected to 192,192.

  In this way, the rotational force transmitted to the auxiliary transmission shaft 116 is output from 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 → Small differential gear support shaft 184 → Each 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 It is transmitted to the wheels 9,9.

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

  The cylindrical shaft supports 189 and 189 can be detached from the case body 54 by removing the mounting bolts 195 and 195 and then pulling them outward from the mounting openings 194 and 194. At this time, each large differential gear support is supported. The shafts 186 and 186 can also be removed from the differential case 182 integrally with the cylindrical shaft supports 189 and 189.

  Accordingly, 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 case body 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 removably attached between the side wall of the case main body 54 and the outer peripheral surface base portion of the rear axle case 8 so that the brake case 196 is detached from these brake cases. The traveling brake 192 can be detached from the tip of the large differential gear support shaft 186 integrally with the 196.

  In this way, the differential mechanism 48 has a configuration in which the large reduction gear 183 is engaged with the output bevel gear 180 from the right side, as shown in FIG. 9A, and as shown in FIG. 9B, A configuration in which the differential mechanism 48 is turned upside down and the left and right are changed over and the large reduction gear 183 is attached to the output bevel gear 180 from the left side can be selectively employed.

  Therefore, the forward direction (main work direction) of the tractor A can be easily changed by selecting the attachment form of the differential mechanism 48 in accordance with the work machine connected to the tractor A and the work form.

The side view of the tractor concerning the present invention. The side view of a clutch part and a mission part. Sectional side explanatory drawing of the clutch part and a mission part. Sectional side explanatory drawing of the clutch part. Sectional side explanatory drawing of a main transmission part. Sectional back surface explanatory drawing of the main transmission part. The expanded cross-section back explanatory drawing of the upper part of the main transmission part. Sectional side explanatory drawing of a subtransmission part and a PTO transmission part. Cross-sectional plane explanatory drawing of a differential mechanism. The rear view of a PTO transmission part. The partially cutaway rear view of the PTO transmission unit. Sectional side view of the PTO transmission unit. The cross-sectional top view of the PTO transmission part. The front view of a front case formation body. The front view of an intermediate part case formation body. FIG. 4 is a cross-sectional side view of a PTO transmission unit with a one-speed transmission specification.

Explanation of symbols

A Tractor 1 Airframe frame 2 Motor part 3 Clutch part 4 Mission part 5 Driving part 6 PTO transmission part

Claims (1)

A PTO case having a built-in PTO transmission mechanism is detachably attached in the transmission case so that at least the front part is accommodated, and the PTO case is formed with a front case formation body, an intermediate case formation body, and a rear case formation. A tractor formed in three parts on the body ,
The front case forming body supports the input shaft, the front case forming body and the rear case forming body support the transmission shaft, the intermediate case forming body and the rear case forming body support the PTO shaft,
A tractor characterized in that the gear stage specifications can be changed by changing the intermediate case forming body and the transmission shaft .

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