JP2016214184A - transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmission that has a structure capable of mounting a lifting actuator without widening the full width thereof even when a transmission housing with a wide width is used therefor.SOLUTION: The transmission 3 includes: the transmission housing 7; a lift arm 82 projected rearward from the transmission housing 7; brackets 83, 84 attached at a rear face of the transmission housing 7; and the lifting actuator 81 having an upper end mounted to the lift arm 82, and a lower end mounted to the brackets 83, 84.SELECTED DRAWING: Figure 9

Description

  The present invention relates to a transmission, and more particularly to a transmission provided with a link mechanism for connecting work machines.

  2. Description of the Related Art Conventionally, work vehicles capable of connecting work machines (for example, rotary machines) such as tractors are known. Such a work vehicle includes a PTO shaft that protrudes outward from the transmission housing. And the driving force of an engine is transmitted to a working machine by connecting a working machine to a PTO axis | shaft (refer patent document 1).

  And there are three-point link methods such as standard three-point link or special three-point link for attaching work implements to the tractor, a lower link suspended by a left and right lift arm and lift rod (lift link), The work implement is supported by a total of three links with one top link located at the top (see Patent Document 2).

JP 2007-190967 A JP 2004-225 A

  In such a link mechanism, lifting actuators (for example, hydraulic cylinders) are attached to the left and right lift arms, respectively. The lifting actuator has an upper end attached to the lift arm and a lower end attached to the left and right side surfaces of the transmission housing.

  By the way, the form which shortened front-back length as a form of a transmission housing is desired. In this case, since the width of the transmission housing is widened, it is difficult to dispose the lifting actuator on the left and right side surfaces of the transmission housing in a transmission having a full width.

  An object of the present invention is to provide a transmission having a structure in which an elevating actuator can be attached without widening the entire width even when a wide transmission housing is used.

  The transmission of the present invention includes a transmission housing, a lift arm protruding rearward from the transmission housing, a bracket attached to the rear surface of the transmission housing, an upper end attached to the lift arm, and a lower end attached to the bracket. And a lifting / lowering actuator.

  The transmission may include a knock pin that fixes the bracket to the transmission housing.

  Further, in the above transmission, the bracket includes a mounting seat surface that contacts a rear surface of the transmission housing, and a support portion that protrudes rearward from the mounting seat surface and has a hole for mounting a lower end of the lifting actuator. It is good also as a structure.

  According to the transmission of the present invention, the bracket that supports the lifting actuator is attached to the rear surface of the transmission housing. Thus, even when a wide transmission housing is used, the lifting actuator can be attached without widening the entire width.

  According to the transmission of the present invention, a part of the bolt that fixes the bracket to the transmission housing is replaced with a knock pin. Thereby, since it becomes a structure which receives the load concerning a bracket with a knock pin, the load to a volt | bolt is small and it can suppress the looseness of a volt | bolt. Moreover, the edge part for attaching a volt | bolt from a bracket can be reduced, and a bracket can be reduced in size. Moreover, the accuracy of the bracket mounting position can be increased by using a knock pin instead of the bolt.

  Further, according to the transmission of the present invention, the bracket has the mounting seat surface in contact with the rear surface of the transmission housing, so that the knock pin can be arranged on the mounting seat surface. Further, the bracket projects rearward from the mounting seat surface and includes a support portion having a hole for attaching the lower end of the lifting actuator, so that the lower end of the lifting actuator can be supported behind the transmission housing.

It is an external appearance perspective view of a tractor. It is a figure which shows the power transmission system of a tractor. It is a figure which shows a transmission. It is a figure which shows the structure of a transmission. It is the figure seen from the arrow F of FIG. It is the figure seen from the arrow R of FIG. It is the figure seen from the arrow L of FIG. It is a figure which shows the structure of a transmission housing. It is a figure which shows the principal part structure of the rear surface side of a transmission. It is a rear surface side perspective view of a bracket and a fixing member. It is a front side perspective view of a bracket and a fixing member. It is a rear surface side perspective view of a main block and a rear cover. It is a figure which shows the link mechanism of a tractor. It is a figure which shows the height automatic control of a rotary. It is a figure which shows the height automatic control of a rotary. It is a figure which shows the inclination automatic control of a rotary. It is a figure which shows the inclination automatic control of a rotary.

  The technical idea of the present invention can be applied to all work vehicles such as farm work machines such as tractors, rice transplanters, and combine machines, and special work vehicles such as wheel loaders. Below, it demonstrates using the tractor which is a typical work vehicle.

  First, the tractor 100 will be briefly described.

  FIG. 1 shows a tractor 100. In the figure, the front-rear direction, left-right direction, and up-down direction of the tractor 100 are shown.

  The tractor 100 mainly includes a frame 1, an engine 2, a transmission 3, a front axle 4, and a rear axle 5. Further, the tractor 100 includes a cabin 6. The cabin 6 has a cockpit inside, and a driver's seat, an accelerator pedal, a shift lever, and the like are arranged.

  The frame 1 forms a skeleton at the front portion of the tractor 100. The frame 1 constitutes a chassis of the tractor 100 together with the transmission 3 and the rear axle 5. The engine 2 described below is supported by the frame 1.

  The engine 2 converts thermal energy obtained by burning fuel into kinetic energy. That is, the engine 2 generates rotational power by burning fuel. The engine 2 is connected to an engine control device (not shown). When the operator operates an accelerator pedal or the like, the engine control device changes the operating state of the engine 2 according to the operation. Further, the engine 2 is provided with an exhaust purification device 2E. The exhaust purification device 2E oxidizes particulates, carbon monoxide, hydrocarbons, etc. contained in the exhaust.

  The transmission 3 transmits the rotational power of the engine 2 to the front axle 4 and the rear axle 5. The rotational power of the engine 2 is input to the transmission 3 via a coupling clutch. The transmission 3 is provided with a speed change mechanism 3S (see FIG. 2). When the operator operates a shift lever or the like, the speed change mechanism 3S changes the traveling speed of the tractor 100 according to the operation. The transmission 3 is provided with a front wheel drive mechanism 3F and a work machine drive mechanism 3P (see FIG. 2). When the operator operates the select switch, the front wheel drive mechanism 3F changes the drive mode of the front tire 41 according to the operation. When the operator operates a power switch or the like, the work machine drive mechanism 3P changes the operation mode of the work machine (not shown: for example, a rotary) according to the operation.

  The front axle 4 transmits the rotational power of the engine 2 to the front tire 41. The rotational power of the engine 2 is input to the front axle 4 via the transmission 3. The front axle 4 is provided with a steering device (not shown). When the operator operates the steering wheel, the steering device changes the steering angle of the front tire 41 according to the operation.

  The rear axle 5 transmits the rotational power of the engine 2 to the rear tire 51. The rotational power of the engine 2 is input to the rear axle 5 via the transmission 3. The rear axle 5 is provided with a braking mechanism 5B (see FIG. 2). When the operator operates the brake pedal, the braking mechanism 5B reduces or stops the rotational speed of the rear tire 51 according to the operation. In addition, when the operator operates the handle, the braking mechanism 5B can also reduce or stop the rotational speed of one rear tire 51 according to the operation (this function is referred to as an “auto brake function”).

  Next, the power transmission system of the tractor 100 will be described.

  The power transmission system of the tractor 100 mainly includes a transmission 3, a front axle 4, and a rear axle 5. Here, a description will be given focusing on the structure of the transmission 3.

  FIG. 2 shows a power transmission system of the tractor 100. FIG. 3 shows the transmission 3. FIG. 4 shows the structure of the transmission 3. 5 is a view seen from the arrow F in FIG. 4, and FIG. 6 is a view seen from the arrow R in FIG. 7 is a view seen from the arrow L in FIG.

  The transmission 3 includes a hydraulic unit that is operated by hydraulic oil. For example, the forward clutch 321 and the reverse clutch 322 constituting the forward / reverse switching device 32, the constant speed clutch 341 and the speed increasing clutch 342 constituting the front wheel drive switching device 34, the PTO clutch 351 constituting the work machine drive switching device 35, and the like. is there.

  The main transmission 31 can change the ratio of the rotational speeds of the input shaft 312 and the output shaft 313 steplessly. The continuously variable transmission 311 is connected to an input shaft 312 and an output shaft 313. The input shaft 312 is connected to a plunger block 314 that is rotatably supported. The plunger block 314 delivers high-pressure hydraulic oil and functions as a hydraulic pump 31P. The output shaft 313 is connected to a motor case 315 that is rotatably supported. The motor case 315 rotates by receiving high-pressure hydraulic oil and functions as the hydraulic motor 31M. A forward drive gear 316 and a reverse drive gear 317 are attached to the output shaft 313. The forward drive gear 316 and the reverse drive gear 317 transmit rotational power to the forward / reverse switching device 32.

  The forward / reverse switching device 32 can transmit rotational power via either the forward clutch 321 or the reverse clutch 322. The forward clutch 321 has a forward driven gear 323 that meshes with the forward drive gear 316. The forward clutch 321 operates to transmit the rotational power of the output shaft 313 to the center shaft 325. The reverse clutch 322 has a reverse driven gear 324 that meshes with the reverse drive gear 317 via a reverse gear. The reverse clutch 322 is operated to transmit the rotational power of the output shaft 313 to the center shaft 325. An ultra-low speed drive gear 326, a first speed drive gear 327, and a second speed drive gear 328 are attached to the center shaft 325. The ultra-low speed drive gear 326, the first speed drive gear 327, and the second speed drive gear 328 transmit rotational power to the auxiliary transmission device 33.

  The auxiliary transmission 33 can change the ratio of the rotational speeds of the center shaft 325 and the center shaft 337 to a plurality of stages. The ultra-low speed dog unit 331 is adjacent to the ultra-low speed driven gear 334 that meshes with the ultra-low speed drive gear 326. The ultra-low speed dog unit 331 is operated to transmit the rotational power of the center shaft 325 to the center shaft 337. First-speed dog unit 332 is adjacent to first-speed driven gear 335 that meshes with first-speed drive gear 327. The first speed dog unit 332 operates to transmit the rotational power of the center shaft 325 to the center shaft 337. Second speed dog unit 333 is adjacent to second speed driven gear 336 that meshes with second speed drive gear 328. The second speed dog unit 333 is operated to transmit the rotational power of the center shaft 325 to the center shaft 337. A front drive gear 338 and a rear pinion gear 339 are attached to the center shaft 337. The front drive gear 338 transmits rotational power to the front wheel drive switching device 34 via a counter shaft 33D having a front driven gear 33A, a constant speed drive gear 33B, and an increased speed drive gear 33C. The rear pinion gear 339 transmits rotational power to the rear axle 5 via the differential gear unit 33E.

  The front wheel drive switching device 34 can transmit rotational power via either the constant speed clutch 341 or the speed increasing clutch 342. The constant speed clutch 341 has a constant speed driven gear 343 that meshes with the constant speed drive gear 33B. The constant speed clutch 341 is operated to transmit the rotational power of the counter shaft 33D to the center shaft 345. The speed increasing clutch 342 has a speed increasing driven gear 344 that meshes with the speed increasing drive gear 33C. The speed increasing clutch 342 operates to transmit the rotational power of the counter shaft 33D to the center shaft 345. A propeller shaft 346 is attached to the center shaft 345. A front pinion gear 347 is attached to the propeller shaft 346. The front pinion gear 347 transmits rotational power to the front axle 4.

  With such a structure, the transmission 3 can change the traveling speed of the tractor 100 (the traveling speed including the stop). Further, the transmission 3 can change the traveling direction (forward or reverse) of the tractor 100. Further, the transmission 3 can change the driving mode of the front tire 41 (constant speed four-wheel drive, speed-up four-wheel drive or non-drive).

  The work machine drive switching device 35 can transmit rotational power via the PTO clutch 351. The PTO clutch 351 has a driven gear 352 that meshes with the drive gear 318. The PTO clutch 351 transmits the rotational power of the input shaft 312 to the center shaft 353 by operating. The center shaft 353 is provided with a first speed drive gear 354, a second speed drive gear 355, a third speed drive gear 356, a fourth speed drive gear 357, and a reverse drive gear 358. The first speed drive gear 354, the second speed drive gear 355, the third speed drive gear 356, the fourth speed drive gear 357, and the reverse drive gear 358 transmit rotational power to the work machine transmission 36.

  The work machine transmission 36 can change the ratio of the rotational speeds of the center shaft 353 and the center shaft 369 to a plurality of stages. The first dog unit 361 is disposed between the first speed driven gear 364 and the second speed driven gear 365. The first dog unit 361 transmits the rotational power of the center shaft 353 to the center shaft 369 via the first-speed drive gear 354 and the first-speed driven gear 364 as the sleeve slides in one direction. Further, the first dog unit 361 transmits the rotational power of the center shaft 353 to the center shaft 369 via the second-speed drive gear 355 and the second-speed driven gear 365 as the sleeve slides to the other side. Second dog unit 362 is adjacent to third-speed driven gear 366. The second dog unit 362 transmits the rotational power of the center shaft 353 to the center shaft 369 via the third-speed drive gear 356 and the third-speed driven gear 366 as the sleeve slides in one direction. The third dog unit 363 is disposed between the fourth speed driven gear 367 and the reverse driven gear 368. The third dog unit 363 transmits the rotational power of the center shaft 353 to the center shaft 369 via the four-speed drive gear 357 and the four-speed driven gear 367 as the sleeve slides in one direction. Further, the third dog unit 363 transmits the rotational power of the center shaft 353 to the center shaft 369 via the reverse drive gear 358, the reverse gear, and the reverse drive gear 368 as the sleeve slides to the other side. A drive shaft 36A is attached to the center shaft 369. A PTO drive gear 36B is attached to the drive shaft 36A. The PTO drive gear 36B transmits rotational power to the work machine via a PTO shaft 36D having a PTO driven gear 36C.

  With such a structure, the transmission 3 can freely change the operating speed of the work machine (the operating speed including the stop). Moreover, the transmission 3 can change the working direction (forward rotation or reverse rotation) of the work machine.

  Next, the transmission housing 7 will be described.

  FIG. 8 shows the configuration of the transmission housing 7. In the figure, the front-rear direction, the left-right direction, and the up-down direction of the tractor 100 are shown.

  The transmission housing 7 mainly includes a main block 71, a center block 72, a front cover 73, and a rear cover 74.

  The main block 71 is a main structure of the transmission housing 7. The main block 71 is a cast product made of gray cast iron (for example, FC250). The main block 71 has a plurality of bearing holes inside thereof.

  The center block 72 is fixed to the front end surface of the main block 71. The center block 72 is a cast product made of an aluminum alloy (for example, ADC 12). The center block 72 is provided with a plurality of bearing holes inside thereof. The center block 72 is fixed to the main block 71 via a gasket 76. The gasket 76 has a hole for passing a bolt.

  The front cover 73 is fixed to the front end surface of the center block 72. The front cover 73 is a cast product made of an aluminum alloy (for example, ADC12). The front cover 73 is provided with a plurality of bearing holes. The front cover 73 is fixed to the center block 72 via a gasket 77. The gasket 77 has holes for passing bolts.

  The rear cover 74 is fixed to the rear end surface of the main block 71. The rear cover 74 is a cast product made of an aluminum alloy (for example, ADC12). The rear cover 74 is provided with a plurality of bearing holes. The rear cover 74 is fixed to the main block 71 via a gasket 78. The gasket 78 has a hole for passing a bolt.

  In addition, a lifting actuator (for example, a hydraulic cylinder) included in a three-point link type link mechanism is attached to the transmission housing 7. Below, the attachment structure of the raising / lowering actuator is demonstrated.

  FIG. 9 is a diagram illustrating a main configuration of the rear side of the transmission 3. The left and right lifting actuators 81 that are components of the link mechanism 8, the left and right lift arms 82 that are lifted and lowered by the lifting actuator 81, and the lifting and lowering are supported at the rear portion of the transmission housing 7. Left and right brackets 83 and 84 that support the lower end of the actuator 81 are provided.

  The lift actuator 81 has an upper end attached to the lower center of the lift arm 82 and a lower end attached to the brackets 83 and 84. The lifting / lowering actuator 81 is rotatably connected around the pin by inserting the pin with the pin hole of the clevis attached to the cylinder and the pin hole of the lift arm 82 being overlapped. Further, the lifting actuator 81 is rotatably connected around the pin when the pin is inserted in a state where the pin hole of the clevis attached to the piston rod and the pin hole of the brackets 83 and 84 are overlapped. Has been.

  The lift arm 82 is attached to the upper part of the transmission housing 7 and protrudes rearward from the transmission housing 7. The lift arm 82 is rotatably connected around the pin by inserting a pin in a state where the pin hole provided at the base end portion overlaps the pin hole of the transmission housing 7. The lift arm 82 has a clevis formed at the tip, and a universal joint (not shown) is attached to the clevis.

  The brackets 83 and 84 are attached to the rear surface of the transmission housing 7. More specifically, it is attached to the left and right lower ends of the rear surface of the main block 71. The structure of the brackets 83 and 84 will be described in detail below.

  10 is a rear perspective view of the brackets 83 and 84 and the fixing member, FIG. 11 is a front perspective view of the brackets 83 and 84 and the fixing member, and FIG. 12 is a rear perspective view of the main block 71 and the rear cover 74.

  The left bracket 83 is a cast product such as an aluminum alloy and has a substantially L-shape when viewed from the left. The bracket 83 includes a flat mounting seat surface 83a that is in contact with the rear surface of the transmission housing 7, and a support portion 83b that protrudes rearward from the lower portion of the mounting seat surface 83a. A cylindrical pin hole 83c penetrating in the left-right direction is formed at the rear end of the support portion 83b. The lower end of the lifting / lowering actuator 81 is attached to the pin hole 83c. Specifically, the pin is inserted in a state where the pin hole of the clevis attached to the piston rod of the lifting / lowering actuator 81 and the pin hole 83c of the bracket 83 are overlapped, so that the pin can be rotated about the pin. Connected.

  Two bolt holes 83d penetrating in the front-rear direction for passing two bolts 831 are formed in the upper part of the bracket 83 side by side. In addition, two pin holes 83e that do not pass through to fit the two knock pins 832 are formed side by side at the bottom of the mounting seat surface 83a. The bracket 83 is fixed to the rear surface of the transmission housing 7 by a fixing member constituted by these bolts 831 and knock pins 832.

  The right bracket 84 is a cast product such as an aluminum alloy, and has a substantially L-shape when viewed from the left. The bracket 84 has a flat mounting seat surface 84a that contacts the rear surface of the transmission housing 7, and a support portion 84b that protrudes rearward from the lower portion of the mounting seat surface 84a. A cylindrical pin hole 84c penetrating in the left-right direction is formed at the rear end of the support portion 84b. The lower end of the lifting / lowering actuator 81 is attached to the pin hole 84c. Specifically, the pin is inserted in a state where the pin hole of the clevis attached to the piston rod of the lifting / lowering actuator 81 and the pin hole 84c of the bracket 84 are overlapped, so that the pin can be rotated about the pin. Connected.

  In the upper part of the bracket 84, two bolt holes 84d penetrating in the front-rear direction for passing two bolts 841 are formed side by side. In addition, two pin holes 84e that do not pass through to fit the two knock pins 842 are formed side by side at the lower portion of the mounting seat surface 84a. The bracket 84 is fixed to the rear surface of the transmission housing 7 by a fixing member constituted by these bolts 841 and knock pins 842.

  As shown in FIG. 12, flat mounting seat surfaces 71 a and 71 b for mounting brackets 83 and 84 are formed on the rear surface of the transmission housing 7, specifically, on the left and right lower ends of the rear surface of the main block 71. . Two bolt holes 71c for fixing the two bolts 831 and two pin holes 71d for fitting the two knock pins 832 are formed in the mounting seat surface 71a. On the other hand, two bolt holes 71e for fixing the two bolts 841 and two pin holes 71f for fitting the two knock pins 842 are formed in the mounting seat surface 71b.

  The space for forming the mounting seat surfaces 71 a and 71 b is limited to a space that is the left and right lower ends of the rear surface of the main block 71 and is not covered by the rear cover 74. In the present embodiment, since the rear cover 74 has a left-right asymmetric shape, the left and right mounting seat surfaces 71a, 71b also have a left-right asymmetric shape. Therefore, if the space of the secured mounting seat surfaces 71a and 71b is to be utilized to the maximum extent, the left and right brackets 83 and 84 are also asymmetric in the left and right direction. When the bolt holes and pin holes are optimally arranged in accordance with the shapes of the brackets 83 and 84, as described above, the bracket 83 has two bolt holes 83d arranged side by side, and the bracket 84 has two bolts. The holes 84d are arranged side by side.

  In this way, by attaching the brackets 83 and 84 that support the lifting actuator 81 to the rear surface of the transmission housing 7, the brackets 83 and 84 do not protrude to the left and right of the transmission housing 7. Even when used, the lifting / lowering actuator 81 can be attached without widening the entire width. The shapes of the brackets 83 and 84 are not particularly limited as long as they can be attached to the rear surface of the transmission housing 7.

  Conventionally, four bolts are used as the fixing members, but the brackets 83 and 84 use two bolts and two knock pins as the fixing members. Thus, by replacing part of the bolts fixed to the transmission housing 7 with knock pins, the load applied to the brackets 83 and 84 is received by the knock pins 832 and 842, so the load on the bolts 831 and 841 is small. The looseness of the bolts 831 and 841 can be suppressed. Note that the number of bolts and knock pins is not particularly limited as long as the brackets 83 and 84 can be fixed stably.

  Moreover, in order to arrange | position a volt | bolt to a bracket, the area | region for forming a bolt hole in an edge part is needed, and a bracket enlarges. However, in the brackets 83 and 84, a part of the bolts arranged at the edge portions is eliminated, and one knock pin is located at a position facing the support portions 83b and 84b on the mounting seat surfaces 83a and 84a of the brackets 83 and 84 in the horizontal direction. 832 is arranged. Thereby, the edge part for arrange | positioning one knock pin 832 is unnecessary, and the edge part can be eliminated. Therefore, the edge part for attaching a bolt from bracket 83,84 can be reduced, and bracket 83,84 can be reduced in size.

  Moreover, the accuracy of the mounting position of the brackets 83 and 84 can be improved by using the knock pin 832 instead of the bolt.

  Further, the brackets 83, 84 have the mounting seat surfaces 83 a, 84 a in contact with the rear surface of the transmission housing 7, so that the knock pin 832 can be disposed on the mounting seat surfaces 83 a, 84 a. Further, the brackets 83 and 84 protrude rearward from the mounting seat surfaces 83a and 84a, and are provided with support portions 83b and 84b having pin holes 83c and 84c for attaching a lower end of the lifting and lowering actuator 81. The lower end of the actuator 81 can be supported behind the transmission housing 7.

  By the way, in addition to the structure shown in FIG. 9, the link mechanism 8 includes, as shown in FIG. 13, a top link 86 for connecting work machines, and a top bracket 85 for rotatably supporting the top link 86. The left and right lower links 87 for connecting the work machines, the left and right lower brackets 88 that rotatably support the lower link 87, the lift link 89 that connects one lift arm 82 and the lower link 87, and the other lift A tilting actuator 8A that connects the arm 82 and the lower link 87 is provided.

  The top bracket 85 has a hinge portion in which two plates that are parallel to each other are welded. The hinge part is provided with a pin hole penetrating the two plates in the horizontal direction.

  The top link 86 is attached to the hinge portion of the top bracket 85. The top link 86 is rotatably connected around the pin P1 when the pin P1 is inserted in a state where the pin hole of the clevis attached to the base end portion and the pin hole of the top bracket 85 are overlapped. ing. Further, the top link 86 is rotatable around the pin by inserting a pin (not shown) in a state where the pin hole of the clevis attached to the tip and the pin hole of the working machine are overlapped. It is connected to.

  The lower bracket 88 is attached to the lower portion of the rear axle 5. The lower bracket 88 has a hinge portion in which two plates that are parallel to each other are welded. The hinge part is provided with a pin hole penetrating the two plates in the horizontal direction.

  The lower link 87 is attached to the hinge portion of the lower bracket 88. The lower link 87 is rotatably connected around the pin P2 by inserting the pin P2 in a state where the pin hole provided at the base end and the pin hole of the lower bracket 88 are overlapped. Further, the lower link 87 is rotatably connected around the rod by hooking a hook attached to the tip of the lower link 87 on a rod (not shown) of the work machine.

  The lift arm 82 has a clevis formed at the tip, and a universal joint 8B is attached to the clevis.

  The lifting / lowering actuator 81 is attached to the center of the lift arm 82. The lift actuator 81 is rotatably connected around the pin P4 by inserting the pin P4 in a state where the pin hole of the clevis attached to the cylinder and the pin hole of the lift arm 82 are overlapped. Yes.

  The lift link 89 is attached to the left lift arm 82 and the lower link 87. The lift link 89 is rotatably connected around the pin P6 by inserting the pin P6 in a state where the pin hole of the clevis attached to the base end portion and the pin hole of the universal joint 8B are overlapped. ing. Further, the lift link 89 is rotatably connected around the pin P7 by inserting the pin P7 in a state where the pin hole of the clevis attached to the tip and the pin hole of the lower link 87 are overlapped. ing.

  The tilting actuator 8A is attached to the right lift arm 82 and the lower link 87. The tilting actuator 8A is rotatably connected around the pin P8 by inserting the pin P8 with the pin hole of the clevis attached to the cylinder and the pin hole of the universal joint 8B being overlapped. Yes. In addition, the tilting actuator 8A is rotatably connected around the pin P9 by inserting the pin P9 with the pin hole of the clevis attached to the piston rod and the pin hole of the lower link 87 being overlapped. Has been.

  With such a structure, when the piston rod of the lifting / lowering actuator 81 is slid and pushed out (when the lifting / lowering actuator 81 is extended), the lift arm 82 is rotated upward. Then, since the lift arm 82 pulls up the left and right lower links 87 via the lift link 89 and the tilting actuator 8A, the height of the rotary 10 (an example of a working machine) increases (see arrow Ra in FIG. 14). Therefore, if this operation is realized in a situation where the rotary 10 is depressed, the tilling depth is maintained in a constant state. It is also possible to raise the rotary 10 before the tractor 100 turns.

  On the contrary, when the piston rod of the lifting / lowering actuator 81 slides and is pulled in (when the lifting / lowering actuator 81 contracts), the lift arm 82 rotates downward. Then, since the lift arm 82 pushes down the left and right lower links 87 via the lift link 89 and the tilting actuator 8A, the height of the rotary 10 is lowered (see arrow Rb in FIG. 15). Therefore, if this operation is realized in a situation where the rotary 10 is lifted, the tilling depth is maintained in a constant state. In addition, the rotary 10 can be lowered after the tractor 100 turns.

  In addition, when the piston rod of the tilting actuator 8A slides and is pushed out (when the tilting actuator 8A is extended), only the lower link 87 on the right side to which the tilting actuator 8A is attached rotates downward. Become. Then, while the left lower link 87 is maintained as it is, the right lower link 87 is pushed down, so that the rotary 10 is inclined downward (see arrow Rc in FIG. 16). Therefore, if such an operation is realized while the tractor 100 is tilted to the left, the rotary 10 is maintained in a horizontal state.

  Conversely, when the piston rod of the tilting actuator 8A is slid and pulled (when the tilting actuator 8A contracts), only the right lower link 87 to which the tilting actuator 8A is attached rotates upward. Become. Then, while the left lower link 87 is maintained as it is, the right lower link 87 is pulled up, so that the rotary 10 is tilted upward (see arrow Rd in FIG. 17). Therefore, if this operation is realized while the tractor 100 is tilted to the right, the rotary 10 is maintained in a horizontal state.

DESCRIPTION OF SYMBOLS 3 Transmission 7 Transmission housing 81 Lifting actuator 82 Lift arm 83 Bracket 83a Mounting seat surface 83b Support part 83c Pin hole (hole)
832 Dowel pin 84 Bracket 84a Mounting seat surface 84b Support part 84c Pin hole (hole)
842 dowel pin

Claims (3)

A transmission housing;
A lift arm protruding rearward from the transmission housing;
A bracket attached to a rear surface of the transmission housing;
A transmission comprising an elevating actuator having an upper end attached to the lift arm and a lower end attached to the bracket.   The transmission according to claim 1, further comprising a knock pin for fixing the bracket to the transmission housing. The bracket is
A mounting seat surface in contact with the rear surface of the transmission housing;
The transmission according to claim 1, further comprising a support portion that protrudes rearward from the mounting seat surface and has a hole for mounting a lower end of the lifting actuator.

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