JP2019006209A - Transmission for work vehicle and work vehicle equipped with the same - Google Patents

Abstract

To achieve easy component management concerning each multiple-disc clutch, easy creation of each control program required for control of each multiple-disc clutch in a transmission for a work vehicle comprising plural transmission changeover devices which is so configured as to be a multiple-disc clutch type.SOLUTION: A transmission for a work vehicle comprises plural transmission changeover devices 31, 32, 81, 82 which are so configured as to be a multiple-disc type such that a transmission state is changed by intermittent operations of multiple-disc clutches 45, 46, 60 to 63, 66, 67, 84, 86. In the plural transmission changeover devices 31, 32, 44, 81, 82, sizes of the multiple-disc clutches 45, 46, 60 to 63, 66, 67, 84, 86 in a radial direction, which are provided on all of the transmission changeover devices, are so set as to be same.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a work vehicle transmission including a plurality of transmission switching devices configured in a multi-plate clutch type in which a transmission state is switched by intermittent operation of a multi-plate clutch, and a work vehicle including the same.

  In the work vehicle transmission as described above, as a plurality of transmission switching devices configured in a multi-plate clutch type, a main shift that can be shifted to 1st to 4th speeds by intermittent operation of four multi-plate clutches (hydraulic clutches). Device, two sub-plate clutches (hydraulic clutches) can be switched between high speed and low speed by intermittent operation, and two multi-plate clutches (hydraulic clutch) can be switched between forward and reverse operation Some are equipped with possible shuttle transmissions. In each of these transmission switching devices, the number of clutch plates (friction plates), the contact area (diameter in the radial direction), etc., designed in consideration of different load conditions depending on the configuration and arrangement thereof, etc. However, it is considered to provide a dedicated multi-plate clutch having different (see, for example, Patent Document 1).

JP 2001-105912 A (paragraph numbers 0015 and 0035, FIGS. 3 to 5)

  In the configuration described in Patent Document 1, the radial size of the multi-plate clutch in each transmission switching device is different, so that when performing maintenance such as replacement of a worn clutch plate, the radial size is different. Since it is necessary to prepare a plurality of types of clutch plates corresponding to each multi-plate clutch, there is room for improvement in terms of component management.

  Further, in controlling the on / off operation of each multi-plate clutch in each transmission switching device by electrohydraulic control, the size of the piston and the like in the radial direction differs depending on the multi-plate clutch, so that the clutch meet in each multi-plate clutch. In order to make these timings the same, it is necessary to change the initial pressure for each multi-plate clutch in accordance with the radial size of the pistons and the like. As a result, it becomes difficult to create each control program necessary for appropriately controlling the intermittent operation of each multi-plate clutch by electrohydraulic control.

  In other words, in a work vehicle transmission equipped with a plurality of transmission switching devices configured in a multi-plate clutch type, it is easy to manage parts for each multi-plate clutch and create each control program required for controlling each multi-plate clutch. It is desired to make it easier to achieve this.

As means for solving the above problems,
A work vehicle transmission according to the present invention includes a plurality of transmission switching devices configured in a multi-plate clutch type in which a transmission state is switched by an intermittent operation of the multi-plate clutch,
In the plurality of transmission switching devices, the radial sizes of the multi-plate clutch provided in all of them are set to the same size.

  According to this means, the clutch plates (drive plates and driven plates), pressure plates, pistons, etc. used for the respective multi-plate clutches of the transmission switching devices are all in the radial direction. It can be a common part common in the plate clutch.

  In controlling the on / off operation of each multi-plate clutch by electrohydraulic control, since the pistons and the like are common parts, the initial pressure for each multi-plate clutch is made the same, so that the clutch meat of each multi-plate clutch can be controlled. The timing can be the same. As a result, it becomes easy to create each control program necessary for appropriately controlling the intermittent operation of each multi-plate clutch by electrohydraulic control.

As one of the means for making the present invention more suitable,
The plurality of transmission switching devices are set to have the same size in the radial direction of the multi-plate clutch provided in all of them, which is suitable for the multi-plate clutch in which the load conditions are most severe. .

  According to this means, in a multi-plate clutch having a margin in terms of load conditions, the number of clutch plates installed in them can be reduced, and the length in the axial direction can be reduced. And in each transmission switching device having a multi-plate clutch capable of shortening the length in the axial direction, the length in the axial direction can be reduced, and the transmission for a work vehicle equipped with them can be reduced. The length in the axial direction can be shortened. As a result, it is possible to reduce the size of the work vehicle transmission.

As one of the means for making the present invention more suitable,
As the plurality of transmission switching devices, forward / reverse switching devices having two multi-plate clutches for forward and reverse, four multi-plate clutches for four-speed shifting, and two multi-plates for two-speed shifting And an 8-speed main transmission having a clutch.

  According to this means, the clutch plate, the pressure plate, and the piston, which are used for a total of eight multi-plate clutches for the forward / reverse switching device and the main transmission, can be used for each multi-plate clutch. Can be a part.

  In controlling the intermittent operation of each multi-plate clutch in the forward / reverse switching device and the main transmission by electrohydraulic control, the initial pressure for each multi-plate clutch is made the same because the pistons and the like are common parts. Thus, the timing of clutch meet in each multi-plate clutch can be made the same. As a result, it becomes easy to create each control program necessary for appropriately controlling the on / off operation of each multi-plate clutch in the forward / reverse switching device and the main transmission by electrohydraulic control.

As one of the means for making the present invention more suitable,
As the plurality of transmission switching devices, a forward / reverse switching device having two forward and backward multi-plate clutches and a working power switching device having working multi-plate clutches are provided.

  According to this means, a clutch plate, a pressure plate, and a piston, which are used for a total of three multi-plate clutches for the forward / reverse switching device and the working power switching device, can be used for each multi-plate clutch. Can be a common part.

  In controlling the intermittent operation of each multi-plate clutch in the forward / reverse switching device and the work power switching device by electrohydraulic control, the initial pressure for each multi-plate clutch is made the same because these pistons are common parts. By doing so, the timing of the clutch meet in each multi-plate clutch can be made the same. As a result, it becomes easy to create each control program necessary for appropriately controlling the intermittent operation of each multi-plate clutch in the forward / reverse switching device and the work power switching device by electrohydraulic control.

As one of the means for making the present invention more suitable,
As the transmission switching device, a drive switching device for driving front wheels having a multi-plate clutch for constant speed transmission is provided.

  According to this means, the clutch plate, the pressure plate, the piston, etc. used for each multi-plate clutch, including the constant-speed transmission multi-plate clutch included in the drive switching device for driving the front wheels, are connected to each other. It can be a common part that can be used for the plate clutch. As a result, it is possible to further facilitate the management of parts in the work vehicle transmission.

As one of the means for making the present invention more suitable,
As the transmission switching device, there is provided a front wheel speed increasing drive switching device having a multi-plate clutch for speed increasing transmission.

  According to this means, the clutch plate, the pressure plate, the piston, etc. used for each multi-plate clutch, including the multi-plate clutch for speed increase transmission possessed by the drive switching device for speed increasing the front wheels, are mutually connected. It can be a common part that can be used for multi-plate clutches. As a result, it is possible to further facilitate the management of parts in the work vehicle transmission.

As one of the means for making the present invention more suitable,
The drive switching device for driving the front wheels and the drive switching device for increasing the front wheels are individually unitized.

  According to this means, it is possible to dispose a gear set for transmitting power via any one of the front wheel drive switching device and the front wheel speed increasing drive switching device. As a result, the two gear sets for transmitting the power via the drive switching device for driving the front wheels and the drive switching device for increasing the front wheels are integrated as a unit as a drive switching unit. There is no need to dispose the drive switching unit far away from both ends.

  That is, the distance between the two gear sets described above can be shortened, and power can be transmitted via these gear sets via the drive switching device for driving the front wheels or the drive switching device for increasing the front wheels. The length of the shaft can be shortened. As a result, it is possible to reduce the weight of the work vehicle transmission including this transmission shaft.

As one of the means for making the present invention more suitable,
The front wheel speed increasing drive switching device is detachable.

  According to this means, the work vehicle transmission can be switched between a two-wheel drive state and a four-wheel drive state by providing only a front-wheel drive drive switching device, a front-wheel drive drive switching device and a front-wheel drive increase. By including the drive switching device for high speed, the specification can be easily changed to the front wheel acceleration specification capable of switching to the two-wheel drive state, the four-wheel drive state, and the front wheel acceleration state. As a result, the versatility of the work vehicle transmission can be enhanced.

As one of the means for making the present invention more suitable,
An output shaft for the front wheels that can be used in each of a mounting specification in which the front wheel speed increasing drive switching device is mounted and a non-mounting specification in which the driving switching device is not mounted is provided.

  According to this means, when the specification of the work vehicle transmission is changed between the above-mentioned specification and the non-attachment specification, it is not necessary to replace the output shaft for the front wheels in accordance with the specification change. As a result, it is possible to easily change the specifications of the work vehicle transmission.

As one of the means for making the present invention more suitable,
In the plurality of transmission switching devices, each of the clutch hub and the clutch housing has a length that allows extension of the clutch plate.

  According to this means, without causing an increase in the size of the work vehicle transmission, each transmission switching device provided in the work vehicle transmission is replaced with, for example, another tractor in which the load condition becomes severe due to the mounting of an engine having a large horsepower. Can be easily accommodated by adding clutch plates. That is, this work vehicle transmission can be made highly versatile and can be used in other work vehicles having different specifications.

As means for solving the above problems,
A work vehicle according to the present invention includes the work vehicle transmission.

  According to this means, by providing the work vehicle transmission described above, it is possible to facilitate parts management in the work vehicle.

It is a left view of a tractor. It is the schematic of the transmission for work vehicles etc. which shows the transmission system of a tractor. It is a cross-sectional top view of the transmission for work vehicles which shows the transmission system of a tractor. FIG. 6 is a cross-sectional plan view of a main part showing a configuration of a first transmission mechanism in the main transmission. It is a cross-sectional top view of the principal part which shows the structure of the 2nd transmission mechanism of a main transmission, and a creep transmission. It is a vertical left side view of the principal part showing the configuration on the first transmission shaft side in the auxiliary transmission. FIG. 6 is a longitudinal left side view of the main part showing the configuration of the second transmission shaft side in the auxiliary transmission. It is a vertical front view of the transmission for work vehicles which shows arrangement | positioning etc. of a transmission shaft. It is a vertical front view of the transmission for work vehicles which shows the shape of a valve unit attachment part, a storage chamber, etc. It is a perspective view of the valve unit attachment part in the transmission for work vehicles. It is XII-XII sectional drawing in FIG. 9 (vertical left side view of a valve unit attachment part). It is a right view of a valve unit. It is a vertical left side view of the principal part which shows the state which divided | segmented the transmission case into front and back in the arrangement | positioning location of a creep transmission. It is the vertical left side view of the principal part which shows the state which divided | segmented the transmission case provided with the creep transmission of another embodiment front and back in the arrangement | positioning location of a creep transmission.

Hereinafter, as an example of an embodiment for carrying out the present invention, an embodiment in which a work vehicle transmission according to the present invention is applied to a tractor which is an example of a work vehicle will be described with reference to the drawings.
The direction indicated by the arrow F in FIGS. 1 and 11 is the front side of the tractor, and the direction indicated by the arrow U is the upper side of the tractor.

  As shown in FIG. 1, the tractor illustrated in the present embodiment includes a driving unit 1 disposed in the front half of the vehicle body, a riding-type driving unit 2 disposed in the rear half of the vehicle body, and a work vehicle transmission (hereinafter referred to as a vehicle vehicle transmission) 3. The fuel tank 4 disposed adjacent to the left side of the transmission 3, the left and right front wheels 5 disposed so as to be able to be driven and steered to the left and right of the prime mover 1, and to be driven to the left and right of the transmission 3 The left and right rear wheels 6 arranged, and the link mechanism 7 for connecting the working device attached to the rear end portion of the transmission 3 so as to be able to swing up and down are provided.

  The prime mover 1 includes a front frame 8 disposed on the front side of the vehicle body, an engine 9 supported on the rear side of the front frame 8, a swingable bonnet 10 that covers the engine 9 and the like. I have. The engine 9 has an output shaft 9 </ b> A (see FIG. 2) that protrudes rearward toward the rear transmission 3.

  The driving unit 2 includes a cabin 11 supported by the transmission 3 in an anti-vibration manner, a steering wheel 12 for a priori steering disposed on the front side inside the cabin 11, and a driving seat disposed on the rear side inside the cabin 11. 13, etc.

  As shown in FIGS. 1 to 3, the transmission 3 includes a transmission case (hereinafter referred to as a T / M case) 14 that serves as a rear frame of the vehicle body and an oil tank, an input shaft 15 to which power from the engine 9 is input, First output shaft 16 for front wheels that outputs power for driving front wheels, second output shafts 17 for left and right rear wheels that output power for driving rear wheels, PTO shaft 18 that outputs power for work, input A traveling transmission system 19 that transmits power input to the shaft 15 to the first output shaft 16 and the left and right second output shafts 17; and a work transmission system 20 that transmits power input to the input shaft 15 to the PTO shaft 18. Etc. As for the 1st output shaft 16 and the PTO shaft 18, those axial center directions are set to the front-back direction of the vehicle body. The left and right second output shafts 17 have their axial directions set to the left-right direction of the vehicle body.

  The T / M case 14 is bolted to the rear end of the first case 21 that is bolted to the rear end of the engine 9, the second case 22 that is bolted to the rear end of the first case 21, and the rear end of the second case 22. The third case 23, the fourth case 24 bolted to the rear end of the third case 23, the fifth case 25 bolted to the lower end of the second case 22, and the left and right ends of the fourth case 24 The left and right sixth cases 26 are connected with bolts. That is, the T / M case 14 is configured in a seven-divided structure that can be divided into seven cases 21 to 26. The second case 22 includes a front cover 27 that is bolted to the inner flange 22 </ b> A, a first support wall 28 that is bolted to the rear end of the second case 22, and the like. The second case 22 is integrally formed with a partition wall 22B that divides the internal space into a front space and a rear space. The third case 23 includes a second support wall 29 and the like that are bolt-connected to the inner connecting portion 23A. A partition wall 23 </ b> B that partitions the internal space and the internal space of the fourth case 24 is integrally formed at the rear end of the third case 23. The fourth case 24 includes a rear cover 30 that is bolted to the rear end thereof.

  As shown in FIGS. 2 to 9, the travel transmission system 19 includes an electro-hydraulic control type forward / reverse switching device 31 that switches power input to the input shaft 15 between power for forward travel and power for reverse travel. Electrohydraulic control type main transmission 32 that shifts the driving power from the forward shift device 31 to eight stages, creep transmission 33 that shifts the driving power from the main transmission 32 to two stages, and creep transmission A sub-transmission device 34 that shifts the driving power from 33 in three stages, a distribution shaft 35 that distributes the driving power from the sub-transmission device 34 back and forth, and the driving power distributed by the distribution shaft 35 to the front wheels A reduction gear set 36 that decelerates for driving, an electrohydraulic control type drive switching unit 37 that switches a transmission state from the reduction gear set 36 to the first output shaft 16, and a distribution shaft while allowing the differential of the left and right rear wheels 6 From 35 A rear wheel differential device 38 that distributes the driving power to the left and right rear wheels 6, and left and right planetary gear speed reducers 39 that decelerate the driving power from the rear wheel differential device 38 to drive the rear wheels, In addition, left and right side brakes 40 that act on the left and right differential shafts 38A of the rear wheel differential device 38 are provided.

  The rear wheel differential device 38 includes a hydraulic differential switching mechanism 38B that switches its operating state between a differential allowable state and a differential stop state. The left and right planetary gear speed reducers 39 transmit the power after deceleration by them to the left and right rear wheels 6 via the left and right second output shafts 17.

  As shown in FIG. 1, the power for driving the front wheels from the first output shaft 16 is externally transmitted while allowing the differential between the external transmission shaft 41 rotating integrally with the first output shaft 16 and the left and right front wheels 5. Power for driving the front wheels from the shaft 41 is transmitted to the left and right front wheels 5 via a front wheel differential (not shown) that distributes the power to the left and right front wheels 5. The front wheel differential device includes a hydraulic differential switching mechanism that switches its operating state between a differential allowable state and a differential stop state.

  As shown in FIGS. 2 to 3 and 8, the work transmission system 20 includes an upper relay shaft 42 for transmitting work power and disposed on the same axis as the input shaft 15 in a state of rotating integrally with the input shaft 15. A lower relay shaft 43, a work power switching device 44 for switching the transmission state from the lower relay shaft 43 to the PTO shaft 18, and the like are provided.

  As shown in FIGS. 2 to 3 and 9, the forward / reverse switching device 31 is input below the forward multi-plate clutch 45, the reverse multi-plate clutch 46 and the input shaft 15 arranged on the input shaft 15. A reverse rotation shaft 47 arranged in parallel with the shaft 15, a forward output gear 48 that outputs the power transmitted through the forward multi-plate clutch 45 as forward power, and a reverse multi-plate clutch 46. A reverse gear set 49 for transmitting the generated power to the reverse rotation shaft 47, a reverse output gear 50 for outputting the reverse rotation power of the reverse rotation shaft 47 as reverse power, and the like are provided. That is, the forward / reverse switching device 31 employs a multi-plate clutch type transmission switching device in which the transmission state is switched by the intermittent operation of the two multi-plate clutches 45 and 46 for the front wheels and the reverse drive.

  In the forward / reverse switching device 31, the front end side of the input shaft 15 and the front end portion of the reverse rotation shaft 47 are supported by the front cover 27, and the rear end portion of the input shaft 15 and the rear end portion of the reverse rotation shaft 47 are second. By being supported by the partition wall 22 </ b> B of the case 22, it is disposed in the front space inside the second case 22.

  2 to 5 and 8 to 9, the main transmission 32 includes an input first transmission shaft 51, a relay second transmission shaft 52, an output third transmission shaft 53, and a first transmission. An eight-speed transmission having a first transmission mechanism 54 that shifts the power input to the shaft 51 in four stages, a second transmission mechanism 55 that shifts the power after the shift by the first transmission mechanism 54 into two stages of high and low, and the like. It is structured in an equation. The first transmission mechanism 54 intermittently transmits power to the four transmission gear sets 56 to 59 and the corresponding transmission gear sets 56 to 59 that are transmitted from the first transmission shaft 51 to the second transmission shaft 52 at different transmission ratios. 4 shift multi-plate clutches 60 to 63, and the like. The second speed change mechanism 55 intermittently transfers power from the two reduction gear sets 64 and 65 and the corresponding reduction gear sets 64 and 65 that are transmitted from the second transmission shaft 52 to the third transmission shaft 53 at different speed ratios. Two deceleration multi-plate clutches 66, 67, and the like. That is, the main transmission 32 includes a multi-plate clutch type transmission switching device in which the transmission state is switched by the intermittent operation of the four shift multi-plate clutches 60 to 63 and the two deceleration multi-plate clutches 66 and 67. It has been adopted.

  In the main transmission 32, the front end portions of the transmission shafts 51 to 53 are supported by the partition wall 22B of the second case 22, and the rear end portions of the transmission shafts 51 to 53 are supported by the first support wall 28. Due to this, it is arranged in the rear space inside the second case 22.

  In the main transmission 32, the three transmission shafts 51 to 53 are arranged in parallel in a state in which their axial directions are set in the longitudinal direction of the vehicle body. The second transmission shaft 52 employs a cylindrical shaft that is externally fitted to the upper relay shaft 42 of the work transmission system 20 so as to be relatively rotatable. The third transmission shaft 53 is arranged adjacent to the front and rear on the same axis as the first transmission shaft 68 for input in the auxiliary transmission 34.

  As shown in FIGS. 2 to 3 and 5, the creep transmission device 33 includes a third transmission shaft 53 of the main transmission device 32 serving as an upper transmission shaft for the creep transmission device 33 and a first transmission of the auxiliary transmission device 34. The shaft 68 is disposed between the third transmission shaft 53 of the main transmission 32 and the first transmission shaft 68 of the auxiliary transmission 34 so that the lower transmission shaft with respect to the creep transmission 33 is provided.

  The creep transmission device 33 is a reduction mechanism 69 that decelerates the power from the third transmission shaft 53 of the main transmission device 32, and the third transmission shaft 53 of the main transmission device 32 to the first transmission shaft 68 of the auxiliary transmission device 34. A synchromesh type switching mechanism 70 for switching the transmission state between a constant speed state in which the power from the third transmission shaft 53 is directly transmitted to the first transmission shaft 68 and a deceleration state in which the power is transmitted via the speed reduction mechanism 69. Have. That is, the creep transmission device 33 employs a synchromesh transmission switching device in which the transmission state is switched by a switching operation of the synchromesh switching mechanism 70.

  The speed reduction mechanism 69 employs a creep speed change mechanism that reduces power from the third transmission shaft 53 of the main transmission 32 to an ultra-low speed through two speed reduction gear sets 71 and 72 having a large speed ratio. Yes.

  As shown in FIGS. 2 to 3 and FIGS. 6 to 7, the auxiliary transmission 34 has the first transmission shaft 68, the second transmission shaft 73 arranged in parallel with the first transmission shaft 68, and the first transmission shaft 68 with different transmission ratios. Three transmission gear sets 74 to 76 that transmit power from the first transmission shaft 68 to the second transmission shaft 73, and a synchromesh first switching mechanism that intermittently transmits power from the first transmission shaft 68 to the reduction gear set 72 for high speed. 77, a synchromesh-type second switching mechanism 78 for intermittently transmitting power from the medium-speed and low-speed transmission gear sets 75, 76 to the second transmission shaft 73, and the transmission transmitted to the second transmission shaft 73. An output gear set 79 that outputs the subsequent power to the distribution shaft 35 is provided. That is, the subtransmission 34 employs a synchromesh transmission switching device in which the transmission state is switched by a switching operation of the two synchromesh switching mechanisms 70.

  The auxiliary transmission 34 has a front end portion of the first transmission shaft 68 and a front end portion of the second transmission shaft 73 supported by the second support wall 29, and a rear end portion of the first transmission shaft 68 and the second transmission shaft 73. The rear end portion is supported by the partition wall 23 </ b> B of the third case 23, so that it is disposed in the internal space of the third case 23.

  As shown in FIGS. 2 and 8 to 9, the drive switching unit 37 includes a front wheel transmission shaft 80 disposed in parallel with the first output shaft 16 directly above the first output shaft 16, and a first front wheel drive first shaft. A drive switching device 81, a second drive switching device 82 for front wheel speed increase, and the like are included. In the drive switching unit 37, the front end of the front wheel transmission shaft 80 is supported by the partition wall 22B of the second case 22, the rear end of the front wheel transmission shaft 80 is supported by the first support wall 28, and the first output. Since the shaft 16 is supported by the fifth case 25, the shaft 16 is disposed across the rear space inside the second case 22 and the internal space of the fifth case 25.

  The first drive switching device 81 includes a reduction gear set 83 that decelerates the power for driving the front wheels from the reduction gear set 36 for constant speed drive, and a multiplicity for constant speed transmission that intermittently transmits to the reduction gear set 83. A plate clutch 84, and the like. The reduction gear set 83 decelerates the power for driving the front wheels so that the left and right front wheels 5 are driven at the same peripheral speed as the left and right rear wheels 6 and transmits the power from the front wheel transmission shaft 80 to the first output shaft 16. The multi-plate clutch 84 for constant speed transmission includes a transmission state in which the left and right front wheels 5 are driven at the same peripheral speed as the left and right rear wheels 6, and a cut-off state in which the left and right front wheels 5 are driven by the propulsive force of the left and right rear wheels 6. And switch to That is, the first drive switching device 81 employs a multi-plate clutch type transmission switching device in which the transmission state is switched by intermittent operation of the multi-plate clutch 84 for constant speed transmission.

  The second drive switching device 82 includes a speed increasing gear set 85 for increasing the power for driving the front wheels from the speed reducing gear set 36 for speed increasing driving, and a speed increasing transmission for intermittently transmitting power to the speed increasing gear set 85. For example, a multi-plate clutch 86. The speed increasing gear set 85 increases the power for driving the front wheels so that the left and right front wheels 5 are driven at a peripheral speed about twice that of the left and right rear wheels 6 to increase the power output from the front wheel transmission shaft 80 to the first output shaft. Tell 16 The multi-plate clutch 84 for speed-up transmission is driven by a driving state in which the left and right front wheels 5 are driven at a circumferential speed approximately twice that of the left and right rear wheels 6, and the left and right front wheels 5 are driven by the propulsive force of the left and right rear wheels 6. Switch to the shut-off state. That is, the second drive switching device 82 employs a multi-plate clutch type transmission switching device in which the transmission state is switched by the intermittent operation of the multi-plate clutch 84 for speed increasing transmission.

  In the drive switching unit 37, the multi-plate clutch 84 for constant speed transmission and the multi-plate clutch 86 for speed increase transmission are supported by the front side of the front wheel transmission shaft 80. Further, the multi-plate clutch 86 for speed increasing transmission is arranged side by side on the front wheel transmission shaft 80 in a state where it is supported on the rear side of the front wheel transmission shaft 80.

  As shown in FIGS. 2 to 3, the working power switching device 44 is a hydraulic PTO clutch 87 that intermittently supplies working power from the lower relay shaft 43, and the power transmitted through the PTO clutch 87 is high or low. There are a constant mesh type first transmission mechanism 88 that shifts to a stage, a constant mesh type second transmission mechanism 89 that shifts power after shifting by the first transmission mechanism 88 to two stages of high and low, and the like. A multi-plate clutch is employed as the PTO clutch 87. In other words, the work power switching device 44 has a multi-plate whose transmission state is switched by the intermittent operation of the multi-plate clutch (PTO clutch) 87 for work and the switching operation of the two constant mesh transmission mechanisms 88 and 89. A clutch-type and constant-mesh type transmission switching device is employed. The work power switching device 44 is disposed in the internal space of the fourth case 24 by being supported by the rear cover 30 or the like.

  With the above-described configuration, the transmission 3 includes a forward / reverse switching device 31 having four multi-plate clutches 45 and 46 for front wheels and a reverse drive as a plurality of transmission switching devices configured in a multi-plate clutch type. Main transmission 32 having shift multi-plate clutches 60-63 and two deceleration multi-plate clutches 66, 67, first drive switching device 81 having multi-plate clutch 84 for constant speed transmission, for speed increase transmission The second drive switching device 82 having the multi-plate clutch 84 and the working power switching device 44 having the working multi-plate clutch 87 are provided.

  As shown in FIGS. 2 to 5 and 8, in the main transmission 32, the four transmission multi-plate clutches 60 to 63 are superior in the transmission direction among the three transmission shafts 51 to 53 arranged in parallel. It arrange | positions along with the front-back direction on the axis | shaft of the 1st transmission shaft 51 arrange | positioned at the side. Thus, the first transmission shaft 51 functions as a transmission shaft that supports the four transmission multi-plate clutches 60 to 63. The two deceleration multi-plate clutches 66 and 67 are arranged in the front-rear direction on the axis of the third transmission shaft 53 disposed on the lower side in the transmission direction among the three transmission shafts 51 to 53 disposed in parallel. Has been placed. Thus, the third transmission shaft 53 functions as a speed reducing shaft that supports the two speed reducing multi-plate clutches 66 and 67. In the main transmission 32, four shift multi-plate clutches 60 to 63 and two deceleration multi-plate clutches 66 and 67 are arranged in parallel so as to be adjacent in the radial direction. .

  That is, in the main transmission 32, the four speed change multi-plate clutches 60 to 63 and the two speed reduction multi-plate clutches 66 and 67 are arranged at the same position in the longitudinal direction of the vehicle body. Thereby, for example, compared with a case where the four shift multi-plate clutches 60 to 63 and the two deceleration multi-plate clutches 66 and 67 are arranged at different positions in the longitudinal direction of the vehicle body. Thus, the front-rear length of the main transmission 32 can be shortened, and the front-rear length of the transmission 3 including the main transmission 32 can be shortened. As a result, it is possible to prevent an increase in the size of the tractor in which the entire length of the tractor is increased due to an increase in the longitudinal length of the transmission 3.

  As shown in FIGS. 2 and 8, in the main transmission 32, the second transmission shaft 52 of the three transmission shafts 51 to 53 arranged in parallel is a first transmission shaft (transmission shaft) as an intermediate shaft. 51 and a third transmission shaft (deceleration shaft) 53.

  As a result, the four transmission gear sets 56 to 59 that transmit power from the first transmission shaft 51 to the second transmission shaft 52 are respectively connected to the first transmission gears 56A to 59A arranged on the shaft of the first transmission shaft 51. The second transmission gears 56 </ b> B to 59 </ b> B can be configured on the second transmission shaft 52. Further, two sets of reduction gear sets 64 and 65 that are transmitted from the second transmission shaft 52 to the third transmission shaft 53 are first reduction gears 64A and 65A arranged on the axis of the second transmission shaft 52, respectively. It can be configured by second reduction gears 64B and 65B arranged on the axis of the third transmission shaft 53.

  That is, each of the four sets of transmission gear sets 56 to 59 and the two sets of reduction gear sets 64 and 65 can be configured with a minimum gear quantity (two). As a result, the main transmission 32 can be made compact and the configuration can be simplified by reducing the number of parts.

  In the main transmission 32, the second transmission gear 56B of the second speed gear set 57 of the four sets of transmission gear sets 56 to 59 is used for the high speed of the two sets of reduction gear sets 64 and 65. The first reduction gear 65A of the reduction gear set 65 is also used. As a result, it is possible to further reduce the size of the main transmission 32 and simplify the configuration by reducing the number of parts.

  As shown in FIG. 8, in the main transmission 32, the three transmission shafts 51 to 53 arranged in parallel are substantially the second transmission shaft (intermediate shaft) 52 as an upper vertex in the longitudinal direction of the vehicle body. They are arranged to form an isosceles triangle.

  Thereby, in the main transmission 32, the first transmission shaft 51 which becomes heavy when the four multiplate clutches 60 to 63 for shifting or the two multiplate clutches 66 and 67 for deceleration are arranged on the shaft. The third transmission shaft 53 is arranged side by side at the lower part of the main transmission 32. In addition, the second transmission shaft 52 that is lightened when the transmission multi-plate clutches 60 to 63 and the deceleration multi-plate clutches 66 and 67 are not disposed on the shaft is intermediate between the first transmission shaft 51 and the third transmission shaft 53. And, it is arranged at a position above the first transmission shaft 51 and the third transmission shaft 53.

  That is, the main transmission 32 can be arranged in the internal space of the second case 22 in a state where the left and right balance is improved with a low center of gravity. As a result, the stability of the tractor including the transmission 3 including the main transmission 32 can be improved.

  As shown in FIG. 8, in the main transmission 32, the three transmission shafts 51 to 53 arranged in parallel include the transmission multi-plate clutches 60 to 63 and the deceleration multi-plate clutches 66 and 67. A second transmission shaft (intermediate shaft) 52 not disposed on the shaft is a pair of upper and lower spaces 90 having a substantially triangular shape formed between the multi-plate clutches 60 to 63 for speed change and the multi-plate clutches 66 and 67 for reduction. 91 is in the upper space 90.

  As a result, the vertical length of the main transmission 32 can be shortened, and the vertical length of the transmission 3 including the main transmission 32 can be shortened. As a result, the height position of the driving unit 2 disposed above the transmission 3 can be lowered, and the vehicle height of the tractor can be lowered.

  Further, as described above, the second transmission shaft 52 is a cylindrical shaft that is externally fitted to the upper relay shaft 42 of the work transmission system 20 so as to be relatively rotatable. The upper space 90 formed between the plate clutches 60 to 63 and the deceleration multi-plate clutches 66 and 67 enters. Thereby, the upper relay shaft 42 can be arranged in the internal space of the second case 22 without securing a dedicated arrangement space for passing the upper relay shaft 42.

  As shown in FIG. 8, among the three transmission shafts 51 to 53, the first transmission shaft 51 and the second transmission shaft 52 have at least the shaft centers of the front wheel transmission shaft 80 and the first output shaft 16. They are arranged so as to be laterally distributed so as to have a substantially laterally symmetrical positional relationship with respect to a line connecting any one of the axial centers and the axial center of the second transmission shaft 52.

  As shown in FIG. 8, in the drive switching unit 37, the multi-plate clutch 84 for constant speed transmission and the multi-plate clutch 86 for speed increase transmission are arranged on the upper side thereof with the speed change multi-plate clutches 60 to 63 and the speed reducing transmission. It is arranged below the main transmission 32 in a state where it enters a lower space 91 formed between the multi-plate clutches 66 and 67.

  Thereby, the vertical length of the 2nd case 22 with which the main transmission 32 and the drive switching unit 37 are arrange | positioned in internal space can be shortened, and the vertical length of the transmission 3 provided with them can be shortened. it can. As a result, the height position of the driving unit 2 disposed above the T / M case 14 can be lowered, and the vehicle height of the tractor can be lowered.

  Further, the multi-plate clutch 84 for constant speed transmission and the multi-plate clutch 86 for speed increase transmission are arranged below the main transmission 32, so that these multi-plate clutches 84, 86 are connected to the main transmission 32. The center of gravity of the transmission 3 including the main transmission 32 and the drive switching unit 37 can be lowered as compared with the case where it is disposed above. As a result, the stability of the tractor including the transmission 3 can be improved.

  As shown in FIGS. 2 to 5 and 8, among the five transmission switching devices 31, 32, 44, 81, 82 described above, the forward / reverse switching device 31 and the main transmission device 32 provided in the traveling transmission system 19. The first drive switching device 81 and the second drive switching device 82 are disposed in the internal space of the second case 22 as a transmission switching device for traveling. The work power switching device 44 provided in the work transmission system 20 is disposed in the internal space of the fourth case 24 as a work transmission switching device.

  That is, in this transmission 3, each transmission switching device 31, 32, 81, 82 for traveling having multi-plate clutches 45, 46, 60 to 63, 66, 67, 84, 86 that are intermittently operated by electrohydraulic control. Are arranged together in the internal space of the second case 22, the hydraulic operation system for the transmission transmission switching devices 31, 32, 81, 82 for traveling is easily configured in a state of being collected in the second case 22. can do.

  The forward / reverse switching device 31, the main transmission 32, the first drive switching device 81, and the second drive switching device 82 provided as a transmission transmission switching device include a multi-plate clutch 45, The sizes in the radial direction of 46, 60 to 63, 66, 67, 84, 86 are set to the same size.

  Accordingly, the clutch plates (drive plate and driven plate) 92, the pressure plate 93, the piston 94, etc. used for each of the multi-plate clutches 45, 46, 60 to 63, 66, 67, 84, 86 are Can be a common component common to all the multi-plate clutches 45, 46, 60 to 63, 66, 67, 84, 86. As a result, parts management can be facilitated.

  Further, in controlling the intermittent operation of each of the multi-plate clutches 45, 46, 60 to 63, 66, 67, 84, 86 by electrohydraulic control, the piston 94 and the like are common parts, so that each multi-plate clutch The initial pressure for 45, 46, 60 to 63, 66, 67, 84, 86 is made the same so that the timing of clutch meet in each of the multi-plate clutches 45, 46, 60 to 63, 66, 67, 84, 86 can be adjusted. Can be the same. As a result, it becomes easy to create each control program necessary for appropriately controlling the intermittent operation of each multi-plate clutch 45, 46, 60 to 63, 66, 67, 84, 86 by electrohydraulic control.

  In the traveling transmission system 19, the low-speed deceleration multi-plate clutch 66 provided in the second transmission mechanism 55 of the main transmission 32 is decelerated by the reduction gear set 64 for low speed in the main transmission 32, and Since driving power with a large torque before being branched into front wheel driving and rear wheel driving is interrupted, the forward / reverse switching device 31, the main transmission 32, the first drive switching device 81, and the second drive switching. The load conditions are stricter than those of the other multi-plate clutches 45, 46, 60 to 63, 67, 84, 86 provided in each of the devices 82.

  The forward / reverse switching device 31, the main transmission 32, the first drive switching device 81, and the second drive switching device 82 are multi-plate clutches 45, 46, 60 to 63, 66, 67, all of which are provided. The radial sizes of 84 and 86 are set to the same size with a large size suitable for the low-speed deceleration multi-plate clutch 66 at which the load conditions are most severe.

  As a result, in the other multi-plate clutches 45, 46, 60 to 63, 67, 84, and 86 that have more margin in terms of load conditions than the low-speed deceleration multi-plate clutch 66, the clutch plate 92 is provided in them. The number of sheets can be reduced, and the length in the axial direction (the longitudinal direction of the vehicle body) can be shortened. And the forward / reverse switching device 31, the main transmission 32, the first drive switching device 81 having the multi-plate clutches 45, 46, 60 to 63, 67, 84, 86 capable of shortening the axial length. And in the 2nd drive switching device 82, the length of those vehicle body front-back directions can be shortened, and the front-back length of the transmission 3 provided with them can be shortened. As a result, it is possible to prevent an increase in the size of the tractor in which the entire length of the tractor is increased due to an increase in the longitudinal length of the transmission 3.

  In the above configuration, the multi-plate clutches 45, 46, 60 to 63, 66, 67, 84, 86 are increased in size in the radial direction, so that the multi-plate clutches 60 to 63 for shifting and the multi-plate clutches for deceleration are increased. A pair of upper and lower spaces 90 and 91 having a substantially triangular shape formed between the plate clutches 66 and 67 are also enlarged. As a result, the second transmission shaft 52 and the upper relay shaft 42 that enter the upper space 90 as described above can enter the upper space 90 more deeply. Further, as described above, the upper side of the multi-plate clutch 84 for constant speed transmission and the multi-plate clutch 86 for speed increase transmission that enter the lower space 91 can enter the lower space 91 more deeply. .

  As a result, the radial size of each of the multi-plate clutches 45, 46, 60 to 63, 66, 67, 84, 86 is large enough to be suitable for the low-speed deceleration multi-plate clutch 66 where the load conditions are most severe. While setting the same size, it is possible to suppress the occurrence of a problem that the vertical length of the transmission 3 including them becomes long.

  By the way, in the main transmission 32, the low-speed deceleration multi-plate clutch 66 and the high-speed deceleration multi-plate clutch 67 have a torque after deceleration by the low-speed reduction gear set 64 or the high-speed reduction gear set 65. Since the large driving power is interrupted, the load condition becomes stricter than that of each of the shift multi-plate clutches 60 to 63 that interrupts the driving power with a small torque before deceleration. Therefore, if the radial sizes of the multi-plate clutches 60 to 63, 66, and 67 provided in the main transmission 32 are set to the same size as described above, each deceleration multi-plate clutch 66 is The number of clutch plates 92 is greater than that of the multi-plate clutches 60 to 63 for shifting, and the length in the axial direction (vehicle body longitudinal direction) is increased.

  In consideration of this point, in the main transmission 32, four shift multi-plate clutches 60 to 63 whose axial length is shortened are adjacent to the first transmission shaft 51 in the front-rear direction. Has been placed. Two deceleration multi-plate clutches 66 and 67 whose length in the axial direction is longer are arranged adjacent to each other in the front-rear direction on the third transmission shaft 53.

  Thereby, for example, two of the four shift multi-plate clutches 60 to 63 whose length in the axial direction is shortened are arranged adjacent to each other on the axis of the first transmission shaft 51 in the front-rear direction, and Compared to the case where the remaining two are arranged adjacent to each other in the front-rear direction on the axis of the third transmission shaft 53 together with the two deceleration multi-plate clutches 66, 67 whose length in the axial direction is increased. The front and rear length of the main transmission 32 can be shortened. As a result, the front-rear length of the transmission 3 including the main transmission 32 can be shortened, and the tractor including the transmission 3 can prevent the tractor from increasing in length.

  As shown in FIGS. 4 to 5, in each of the multi-plate clutches 45, 46, 60 to 63, 66, 67, 84, 86 in which the diameter is increased as described above, the piston 94 has a large diameter as a whole. Instead, only the pressing portion 94A that presses the clutch plate 92 is formed in a stepped shape having an enlarged diameter.

  Thereby, when the diameter of the entire piston 94 is increased, it is possible to prevent a decrease in the response of the piston 94 caused by an increase in the volume of the piston 94. Further, it is possible to prevent the centrifugal force generated when the piston 94 is rotated due to the increase in the volume of the piston 94 from being increased, and thereby a return requiring a spring force to overcome the centrifugal force is achieved. As the spring 95, a small diameter having a weak spring force can be adopted.

  As shown in FIGS. 2 to 5, in the forward / reverse switching device 31, the forward multi-plate clutch 45 and the reverse multi-plate clutch 46 that are adjacent to each other share a single clutch housing 96. In the main transmission 32, the first-speed multi-plate clutch 60 and the second-speed multi-plate clutch 61 that are adjacent to each other among the four shift multi-plate clutches 60 to 63 share a single clutch housing 97. In addition, the three-speed multi-plate clutch 62 and the four-speed multi-plate clutch 63 adjacent to each other in the front and rear share a single clutch housing 98. Further, two deceleration multi-plate clutches 66 and 67 adjacent to the front and rear share a single clutch housing 99.

  Thus, the front and rear multi-plate clutches 45, 46, 60 to 63, 66, and 67 share the clutch housings 97 to 99, thereby making the forward / reverse switching device 31 and the main transmission 32 compact in the longitudinal direction. In addition, it is possible to improve the assemblability by reducing the number of parts.

  In the forward / reverse switching device 31, the main transmission 32, the first drive switching device 81, and the second drive switching device 82, the clutch housings 96 to 99 and the clutch hubs 100 to 103 each have an additional clutch plate 92. It has a length that allows

  Accordingly, each of the forward / reverse switching device 31, the main transmission 32, the first drive switching device 81, and the second drive switching device 82 provided in the transmission 3 can be used without increasing the size of the transmission 3. By mounting the engine 9 having a large horsepower, it is possible to easily cope with other tractors and the like whose load conditions become severe by adding the clutch plate 92. That is, the transmission 3 can be made highly versatile, which can be used for other tractors with different specifications.

  As shown in FIG. 2, in the drive switching unit 37, the first drive switching device 81 includes a first reduction gear 83 </ b> A of the reduction gear set 83 disposed on the shaft of the front wheel transmission shaft 80, and a constant speed transmission. The multi-plate clutch 84 and the like are unitized with the front wheel transmission shaft 80. In the second drive switching device 82, the first speed increasing gear 85A of the speed increasing gear set 85 disposed on the front wheel transmission shaft 80, the multi-plate clutch 84 for speed increasing transmission, and the like are unitized. ing.

  That is, in the drive switching unit 37, the first drive switching device 81 and the second drive switching device 82 are increased in speed with the second reduction gear 83 </ b> B of the reduction gear set 83 disposed on the axis of the first output shaft 16. The gear sets 85 are individually unitized except for the second speed-up gear 85B.

  Thereby, in the drive switching unit 37, the speed increasing gear set 85 can be disposed between the first drive switching device 81 and the second drive switching device 82, and the first drive switching device 81 and the second drive are arranged. There is no need to dispose the speed increasing gear set 85 behind the second drive switching device 82 as in the case where the switching device 82 is integrated into a unit.

  As a result, the separation distance between the speed increasing gear set 85 and the speed reduction gear set 83 disposed on the front side of the vehicle body relative to the first drive switching device 81 can be shortened, and the second speed reduction gear of the speed reduction gear set 83 can be reduced. The longitudinal length of the first output shaft 16 on which 83B and the second speed increasing gear 85B of the speed increasing gear set 85 are disposed on the shaft, and the longitudinal length of the fifth case 25 that supports the first output shaft 16 The length can be shortened. Thereby, weight reduction of the transmission 3 provided with them can be achieved.

  As shown in FIG. 2, the drive switching unit 37 includes the second drive switching device 82 that is unitized as described above so as to be detachable from the front wheel transmission shaft 80.

  Thus, by performing a simple operation of attaching / detaching the unitized second drive switching device 82 to / from the front wheel transmission shaft 80, the drive switching unit 37 is provided with only the first drive switching device 81, so that the two wheels By switching to a standard specification that can be switched between a driving state and a four-wheel driving state, and a first drive switching device 81 and a second drive switching device 82, the two-wheel driving state, the four-wheel driving state, and the front wheel acceleration state are switched. The specification can be easily changed to the possible front wheel acceleration specification. As a result, the versatility of the transmission 3 can be improved.

  As shown in FIG. 2, the first output shaft 16 is disposed on the shaft in a state where the second reduction gear 83 </ b> B and the second speed increase gear 85 </ b> B rotate integrally, so that the second drive switching device 82 can be operated. It is configured to be usable in each of a standard specification that is not mounted (non-mounted specification) and a front wheel acceleration specification (mounted specification) in which the second drive switching device 82 is mounted.

  Thereby, when the specification of the drive switching unit 37 is changed between the standard specification and the front wheel acceleration specification, it is not necessary to replace the first output shaft 16 in accordance with the specification change. As a result, the specification change of the drive switching unit 37 can be facilitated.

  Although not shown in the drawings, this tractor is based on the operation of a forward / reverse switching lever, a main transmission lever, a front wheel drive selection switch, a differential lock pedal, and the like provided in the driving unit 2, and a forward / reverse switching command, a shift command And an electronic control unit that outputs various control commands such as a front wheel drive switching command.

  As shown in FIGS. 2-3 and 8, in this tractor, the forward / reverse switching device 31, the main transmission 32, the drive switching unit 37, the rear wheel differential device 38, the front wheel differential device, etc. This is a hydraulic device that is electronically hydraulically controlled by the control operation of the electronic control unit. Among these hydraulic devices, a forward / reverse switching device 31, a main transmission 32, a drive switching unit 37, a rear wheel differential device 38, and the like are provided inside the T / M case 14.

  As shown in FIGS. 2 and 3, the transmission 3 includes a pump unit 104 that pumps oil stored in the T / M case 14 toward each hydraulic device such as the forward / reverse switching device 31, and A valve unit 105 that controls the flow of oil to each hydraulic device such as the forward / reverse switching device 31 is provided.

  When the pump unit 104 and the valve unit 105 are disposed at the upper end of the T / M case 14, the pump unit 104 and the valve unit 105 may come into contact with the cabin 11 supported by the transmission 3 in an anti-vibration manner due to vibration during traveling. Therefore, in order to avoid this contact, it is disposed on the right side of the T / M case 14. Since the right side portion of the T / M case 14 is a lateral side portion that is open to the outside where the fuel tank 4 is not adjacent, maintenance of the pump unit 104 and the valve unit 105 is facilitated.

  As shown in FIGS. 2 to 3 and 9 to 10, the T / M case 14 includes a pump unit mounting portion 106 to which the pump unit 104 is mounted from the right outer side and a valve unit 105 from the right outer side of the T / M case 14. And a valve unit attaching portion 107 to which the is attached. The pump unit mounting portion 106 bulges outward from the right side of the third case 23 in the T / M case 14. The valve unit mounting portion 107 is formed on the right side portion of the second case 22 in the T / M case 14.

  As shown in FIGS. 2 to 3, the pump unit 104 includes a dual first hydraulic pump 104 </ b> A attached to the front end of the pump unit attaching portion 106 and a second attached to the rear end of the pump unit attaching portion 106. And a hydraulic pump 104B. The first hydraulic pump 104A and the second hydraulic pump 104B are driven by the power transmitted from the work transmission system 20 through the gear set 108 for driving the pump. The gear set 108 for driving the pump includes a first gear 108A that also serves as a coupling for interlockingly connecting the upper relay shaft 42 and the lower relay shaft 43 to the work transmission system 20, a second gear 108B for relay, and an output. A third gear 108C for use.

  As shown in FIGS. 3, 9, and 11 to 12, the valve unit 105 includes a base plate 110 attached to the valve unit attaching portion 107, and a first valve block 111 and a second valve block 112 having a plurality of electromagnetic valves. , Etc.

  As a plurality of electromagnetic valves, the first valve block 111 is a forward electromagnetic on / off valve 113 that switches the oil flow to the forward multi-plate clutch 45, and a reverse electromagnetic on / off switch that switches the oil flow to the reverse multi-plate clutch 46. 1-speed electromagnetic on / off valve 115 for switching the oil flow to the valve 114 and the 1-speed multi-plate clutch 60 2-speed electromagnetic on-off valve 116 for switching the oil flow to the 2-speed multi-plate clutch 61 A 3-speed electromagnetic on / off valve 117 for switching the oil flow to the multi-plate clutch 62, a 4-speed electromagnetic on / off valve 118 for switching the oil flow to the 4-speed multi-plate clutch 63, and a multi-plate clutch 84 for constant speed transmission. Electromagnetic on / off bar for constant speed transmission 119, an electromagnetic on / off valve 120 for speed increasing transmission for switching the oil flow to the multi-plate clutch 86 for speed increasing transmission, and a rear wheel difference for switching the oil flow to the differential switching mechanism 38B of the differential device 38 for the rear wheel. A dynamic electromagnetic on / off valve 121 and a front wheel differential electromagnetic on / off valve 122 for switching the flow of oil to the differential switching mechanism of the front wheel differential device are provided.

  The second valve block 112, as a plurality of electromagnetic valves, is a forward / backward electromagnetic proportional valve 123 that continuously controls the flow of oil to the forward multiplate clutch 45 and the reverse multiplate clutch 46, and two deceleration multiplates. The low-speed electromagnetic proportional valve 124 for continuously controlling the flow of oil to the low-speed deceleration multi-plate clutch 66 of the clutches 66 and 67, and the high-speed side of the two deceleration multi-plate clutches 66 and 67 The high-speed electromagnetic proportional valve 125 for continuously controlling the flow of oil to the deceleration multi-plate clutch 67 is provided.

  Although not shown, the base plate 110, the first valve block 111, and the second valve block 112 include a plurality of electrohydraulic controls such as the forward / reverse switching device 31, the main transmission 32, and the drive switching unit 37. An internal oil passage is formed.

  As shown in FIGS. 9 to 11, the valve unit mounting portion 107 is formed with a recess 107 </ b> A that partitions the first valve block storage chamber 126 with the base plate 110. The first valve block 111 is assembled to a storage chamber forming surface 110 </ b> A that forms a storage chamber 126 between the base plate 110 and the recess 107 </ b> A of the valve unit mounting portion 107. The second valve block 112 is assembled to the outer surface 110B of the base plate 110 opposite to the storage chamber forming surface 110A.

  As a result, when the valve unit 105 is attached to the valve unit attachment portion 107 of the T / M case 14, the first valve block 111 having the ten electromagnetic on / off valves 113 to 122 is attached to the T / M case 14. The right side portion is configured to be stored in a storage chamber 126 formed separately from the internal space of the T / M case 14. Further, the second valve block 112 having three electromagnetic proportional valves 123 to 125 is configured to be disposed at a position laterally outside the storage chamber 126 in the right side portion of the T / M case 14.

  With the above configuration, iron powder or the like contained in the oil stored in the T / M case 14 is applied to the valve unit 105 by excitation of the electromagnetic on / off valves 113 to 122 and the electromagnetic proportional valves 123 to 125. It can prevent being sucked toward. As a result, due to the suction, iron powder or the like contained in the oil inside the T / M case 14 enters the valve unit 105, and the electromagnetic on / off valves 113 to 122 and the electromagnetic proportional valves The possibility of biting into any of 123 to 125 can be avoided.

  Further, as in the case where the first valve block 111 is disposed in the internal space of the T / M case 14, an opening for allowing the first valve block 111 to enter the internal space of the T / M case 14 is provided in the valve unit mounting portion 107. Therefore, it is possible to prevent a decrease in strength in the T / M case 14 due to the formation of the opening.

  Then, the first valve block 111 having the electromagnetic on / off valves 113 to 122 having a high possibility of oil leakage is housed in the storage chamber 126, and the second valve block 112 having the electromagnetic proportional valves 123 to 125 having a low possibility of oil leakage. Is disposed outside the T / M case 14, and the recess 107A for the storage chamber formed in the T / M case 14 can be narrowed while preventing the oil from leaking to the outside. The internal space of the case 14 can be widened. As a result, it becomes easy to set and assemble the traveling transmission system 19 and the working transmission system 20 arranged in the internal space of the T / M case 14.

  When the valve unit 105 is attached to the valve unit attachment portion 107 of the T / M case 14, at least the upper end portion of the first valve block 111 is the oil surface of the oil stored in the T / M case 14. The mounting height position is set so as to be positioned higher than the height position.

  As shown in FIGS. 3 and 9 to 11, the valve unit mounting portion 107 is configured so that the excess oil from the first valve block 111 is placed in the T / M case 14 at a position above the first valve block 111 in the recess 107 </ b> A. Seven return oil passages 107B are formed to return to the inside.

  As a result, oil leaking from the electromagnetic on / off valves 113 to 122 of the first valve block 111 can be stored as lubricating oil up to a position above the first valve block 111 in the storage chamber 126 in the vehicle body. When the oil surface of the lubricating oil reaches the return oil passage forming portion of the storage chamber 126, the lubricating oil that has reached the return oil passage forming portion is used as surplus oil from each return oil passage 107B to the T / M case 14. Can be returned to the inside. Further, the oil stored in the T / M case 14 flows into the storage chamber 126 from each return oil passage 107 </ b> B together with the iron powder contained in the oil due to a large inclination of the tractor. It is possible to make it difficult for problems to occur.

  As shown in FIGS. 9 to 11, in the valve unit mounting portion 107, seven return oil passages 107B are formed in two upper and lower stages. Thereby, compared with the case where all the return oil passages 107B are formed at the same height position, the oil stored in the T / M case 14 together with the iron powder etc. contained in this oil The problem of flowing into the storage chamber 126 from the return oil passage 107B can be made difficult to occur.

  In the upper and lower two-stage return oil passages 107B, three return oil passages 107B are formed in the upper stage, and four return oil paths 107B are formed in the lower stage, so that the opening area by the upper return oil path 107B is lower. It is formed so as to be narrower than the opening area by the oil passage 107B.

  This is because when the return oil passage 107B is formed in two upper and lower stages, most of the excess oil returns from the lower return oil passage 107B to the inside of the T / M case 14, and the upper return oil passage 107B is used in an auxiliary manner when the amount of oil leaking from each of the electromagnetic on / off valves 113 to 122 is large. Thus, the upper return oil passage 107B is used as an auxiliary. A decrease in strength in the T / M case 14 caused by unnecessarily widening the opening area can be prevented.

  As shown in FIGS. 3, 9, and 11, each return oil passage 107 </ b> B is provided with an oil filter 127. As a result, even if the oil stored in the T / M case 14 flows into the storage chamber 126 from each return oil passage 107 </ b> B, iron powder or the like contained in this oil is stored in the storage chamber 126. Inflow can be prevented. As described above, when the seven return oil passages 107B are formed in two upper and lower stages, when clogging occurs in the oil filter 127 provided in the lower return oil passage 107B, Excess oil in the storage chamber 126 can be returned to the inside of the T / M case 14 from the upper return oil passage 107B.

  As shown in FIGS. 9 to 11, in the valve unit mounting portion 107, the recess 107 </ b> A has a T / M case 14 via a lower recessed portion 107 a in which the first valve block 111 is accommodated and each return oil passage 107 </ b> B. And an upper recessed portion 107b communicating with the inside of the housing. The upper recessed portion 107b is formed to be shallower than the lower recessed portion 107a and narrower than the lower recessed portion 107a.

  Thereby, for example, compared with the case where the upper recessed portion 107b in which the first valve block 111 is not accommodated is formed to have the same recessed depth and the same width as the lower recessed portion 107a, T / The internal space of the M case 14 can be widened. As a result, it becomes easy to set and assemble the traveling transmission system 19 and the working transmission system 20 arranged in the internal space of the T / M case 14.

  Although not shown, the input shaft 15 of the transmission 3 is supported by the front cover 27 and the forward oil passage extending between the front portion of the input shaft 15 supported by the front cover 27 and the forward multi-plate clutch 45. Further, a reverse oil passage extending between the front portion of the input shaft 15 and the reverse multi-plate clutch 46 is formed. The front wheel transmission shaft 80 of the drive switching unit 37 includes a constant speed oil passage extending between the rear end portion of the front wheel transmission shaft 80 supported by the first support wall 28 and the multi-plate clutch 84 for constant speed transmission, and A speed increasing oil passage that extends between the rear end portion of the front wheel transmission shaft 80 supported by the first support wall 28 and the multi-plate clutch 84 for speed increasing transmission is formed.

  As shown in FIGS. 4 to 5 and FIGS. 8 to 11, in the main transmission 32, the three transmission shafts 51 to 53 are configured such that the lower end of the second transmission shaft (intermediate shaft) 52 is the first transmission shaft (transmission shaft). The upper end of the first transmission shaft 51 is positioned below the upper end of the third transmission shaft 53 so that the upper end of the first transmission shaft 53 is positioned above the upper end of the third transmission shaft 53. Are arranged as follows. The first transmission shaft 51 includes a first speed oil passage 51 </ b> A extending between the front end portion of the first transmission shaft 51 supported by the partition wall 22 </ b> B of the second case 22 and the first speed multi-plate clutch 60, and the partition wall of the second case 22. A second-speed oil passage 51B extending between the front end portion of the first transmission shaft 51 supported by 22B and the second-speed multi-plate clutch 61, and a front end portion of the first transmission shaft 51 supported by the partition wall 22B of the second case 22. 3rd speed oil passage 51C extending to the 3rd speed multi-plate clutch 62 and 4th speed extending to the front end portion of the first transmission shaft 51 supported by the partition wall 22B of the second case 22 and the 4th speed multi-plate clutch 63 An oil passage 51D and the like are formed. The third transmission shaft (deceleration shaft) 53 includes a low-speed oil passage 53A extending between the front end of the third transmission shaft 53 supported by the partition wall 22B of the second case 22 and the low-speed-side deceleration multi-plate clutch 66, and A high-speed oil passage 53B extending between the front end of the third transmission shaft 53 supported by the partition wall 22B of the second case 22 and the high-speed-side deceleration multi-plate clutch 67 is formed.

  The valve unit mounting portion 107 is formed at a predetermined position in the longitudinal direction of the vehicle body where the partition wall 22B is formed in the second case 22 of the T / M case 14. The partition wall 22B includes a first-speed internal oil passage 22C extending between the first-speed connection port 105A formed in the valve unit 105 and the first-speed oil passage 51A formed in the first transmission shaft 51, and the valve unit 105. A second speed internal oil passage 22D extending between the formed second speed connection port 105B and the second speed oil passage 51B formed in the first transmission shaft 51, and a third speed connection port formed in the valve unit 105. 3rd speed internal oil passage 22E extending between 105C and 3rd speed oil passage 51C formed in the first transmission shaft 51, 4th speed connection port 105D formed in the valve unit 105 and 1st transmission shaft 51 are formed. A four-speed internal oil passage 22F across the four-speed oil passage 51D, a low-speed connection port 105E formed in the valve unit 105, and a low-speed oil passage 53A formed in the third transmission shaft 53. A low-speed internal oil passage 22G, a high-speed internal oil passage 22H extending between the high-speed connection port 105F formed in the valve unit 105 and the high-speed oil passage 53B formed in the third transmission shaft 53, etc. Is formed.

  As a result, in forming the six hydraulic paths for the main transmission extending between the valve unit 105 and the multi-plate clutches 60 to 63, 66, 67 of the main transmission 32, the hydraulic pressure is provided inside the T / M case 14. Eliminates the need to assemble pipes. Further, the internal oil passages 22C to 22H of the partition wall 22B extending between the valve unit 105 and the first transmission shaft 51 or the third transmission shaft 53 can be formed in the shortest length with a simple linear shape. As a result, it is possible to reduce the number of work steps required to form each hydraulic path for main transmission.

  Further, the internal oil passages 22C to 22H of the partition wall 22B are formed in the shortest length with a simple linear shape, so that the main speed change over the valve unit 105 and the multi-plate clutches 60 to 63, 66, and 67 of the main speed change device 32 is achieved. Therefore, each of the six hydraulic paths can be formed in the shortest shape with a simple shape. As a result, the responsiveness of each of the multi-plate clutches 60 to 63, 66, 67 in the main transmission 32 is improved.

  As shown in FIGS. 3 and 9, the valve unit mounting portion 107 has four shift multi-plate clutches 60 to 63 rather than the third transmission shaft 53 that supports the two deceleration multi-plate clutches 66 and 67. It is arrange | positioned near the 1st transmission shaft 51 which supports these.

  Thereby, compared with the case where the valve unit mounting portion 107 is disposed closer to the third transmission shaft 53 than the first transmission shaft 51, the quantity of the long internal oil passages 22G and 22H formed in the partition wall 22B is reduced. Can be reduced. As a result, it is possible to prevent the strength of the partition wall 22B from being reduced due to an increase in the number of long internal oil passages 22G and 22H formed in the partition wall 22B.

  As shown in FIGS. 2 to 3, 5, and 13, in the creep transmission device 33, the speed reduction mechanism 69 is parallel to the third transmission shaft 53 of the main transmission device 32 and the first transmission shaft 68 of the auxiliary transmission device 34. A shaft of the reduction shaft 130 in a state of rotating integrally with the first reduction gear 71A and the reduction shaft 130 arranged on the shaft of the third transmission shaft 53 in a state of rotating integrally with the arranged reduction shaft 130 and the third transmission shaft 53. The second reduction gear 71B and the third reduction gear 72A arranged on the upper side, the fourth reduction gear 72B arranged on the axis of the first transmission shaft 68 in a state of rotating relative to the first transmission shaft 68, etc. Have. Then, the first reduction gear 71A and the second reduction gear 71B are used to reduce the transmission from the third transmission shaft 53 to the reduction shaft 130 at a large speed ratio among the two reduction gear sets 71 and 72 described above. The reduction gear set 71 is configured. Further, the lower side of the transmission direction in which the third reduction gear 72A and the fourth reduction gear 72B reduce the transmission from the reduction shaft 130 to the first transmission shaft 68 at a large transmission ratio of the two reduction gear sets 71 and 72 described above. The reduction gear set 72 is configured.

  In the reduction mechanism 69, the first reduction gear 71 </ b> A is assembled to the third transmission shaft 53, and the fourth reduction gear 72 </ b> B is assembled to the first transmission shaft 68.

  The switching mechanism 70 is a first meshed arrangement arranged on the shaft of the third transmission shaft 53 so as to rotate integrally with the third transmission shaft 53 in a state in which movement in the axial direction with respect to the third transmission shaft 53 is allowed. The rotating body 131, the second meshed rotating body 132 disposed on the first transmission shaft 68 so as to rotate relative to the first transmission shaft 68 in a state of rotating integrally with the fourth reduction gear 72B, and the first The first speed change is performed so as to rotate integrally with the first speed change shaft 68 in a state in which movement in the axial direction is allowed across the constant speed position meshing with the meshed rotating body 131 and the deceleration position meshing with the second meshed rotating body 132. It has the meshing rotating body 133 etc. which are arrange | positioned on the axis | shaft of the axis | shaft 68, etc., and is assembled | attached to the 1st transmission shaft 68 (refer FIG. 13).

  As a result, by assembling the switching mechanism 70 to the first transmission shaft 68, the meshing rotating body 133 is forced over the constant speed position where the meshing rotating body 133 meshes with the first meshed rotating body 131 and the deceleration position where the meshing rotating body 132 meshes. It is possible to confirm the operation whether or not it moves normally. If a problem occurs in this operation check, the problem can be solved by performing fine adjustment of each of the rotating bodies 131 to 133 assembled to the first transmission shaft 68. As a result, assembly including operation confirmation of the switching mechanism 70 can be facilitated.

  In this creep transmission 33, the first reduction gear 71A of the reduction mechanism 69 and the first meshed rotating body 131 of the switching mechanism 70 are formed independently of each other. Is applied to the first meshed rotating body 131. As a result, it is possible to avoid the possibility that the durability of the first meshed rotating body 131 is reduced due to the load applied to the first reduction gear 71A reaching the first meshed rotating body 131.

  As shown in FIG. 13, the switching mechanism 70 is unitized with the fourth reduction gear 72B. Accordingly, the fourth reduction gear 72B and the switching mechanism 70 can be easily attached to and detached from the first transmission shaft 68.

  As shown in FIGS. 2 to 3, 5, and 13, the T / M case 14 includes a first case 22 and a first case 22 on the upper side in the transmission direction including the third transmission shaft 53 at the location where the creep transmission device 33 is disposed. The division positions of the second case 22 and the third case 23 are set so as to be divided into the third case 23 on the lower side in the transmission direction including the transmission shaft 68. In the speed reduction mechanism 69, only the first speed reduction gear 71A is assembled to the second case 22 together with the third transmission shaft 53, and substantially the entire speed reduction mechanism 69 excluding the first speed reduction gear 71A is switched to the first speed change shaft 68. Together with the mechanism 70, the third case 23 is assembled.

  Thus, when the creep transmission device 33 is assembled to the T / M case 14, the first reduction gear 71 </ b> A of the reduction mechanism 69 is moved from the split end side of the second case 22 with the third case 23 to the third transmission shaft 53. It can assemble | attach to the 2nd case 22 with these. Further, the entire reduction mechanism 69 excluding the first reduction gear 71 </ b> A and the switching mechanism 70 are connected to the third case 23 together with the first transmission shaft 68 and the like from the split end side of the third case 23 with the second case 22. Can be assembled. The first meshed rotating body 131 assembled to the third case 23 is arranged on the axis of the third transmission shaft 53 assembled to the second case 22, and the second assembled to the third case 23. By connecting the second case 22 and the third case 23 so that the reduction gear 71B meshes with the first reduction gear 71A assembled to the second case 22, the creep transmission 33 is connected to the third transmission shaft 53. It can be assembled to the T / M case 14 in a state extending over the first transmission shaft 68. That is, the assembly of the creep transmission device 33 to the T / M case 14 can be simplified.

  When removing the creep transmission device 33 from the T / M case 14, the connection between the second case 22 and the third case 23 is released to separate the second case 22 and the third case 23. The transmission 33 is divided into the first reduction gear 71A assembled to the second case 22, the entire reduction mechanism 69 assembled to the third case 23 except the first reduction gear 71A, and the switching mechanism 70. be able to. By this division, the first reduction gear 71A can be detached from the second case 22 together with the third transmission shaft 53 and the like from the divided end side of the second case 22 with the third case 23. Further, the entire reduction mechanism 69 excluding the first reduction gear 71A and the switching mechanism 70 are separated from the third case 23 together with the first transmission shaft 68 and the like from the split end side of the third case 23 with the second case 22. Can be removed. That is, it is possible to easily remove the creep transmission device 33 from the T / M case 14, thereby facilitating maintenance of the creep transmission device 33.

  As shown in FIGS. 2, 5, and 13, in the creep transmission device 33, the speed reducing shaft 130 has a front end portion supported by the first support wall 28 and a rear end portion at the front end portion of the distribution shaft 35. It is supported. The first reduction gear 71 </ b> A is spline-fitted to the rear portion of the third transmission shaft 53 and is prevented from coming off by a retaining ring 134. The second reduction gear 71B is splined to the front end side of the reduction shaft 130. The third reduction gear 72A is integrally formed with the rear end portion of the reduction shaft 130. The first meshed rotating body 131 is splined to the rear end portion of the third transmission shaft 53 in a state where the first meshed rotating body 131 is supported by the rotating body 135 that is spline fitted to the front end portion of the first transmission shaft 68 so as to be relatively rotatable. ing. The second meshed rotating body 132 is engaged and connected to the fourth reduction gear 72B so as to rotate integrally with the fourth reduction gear 72B. The meshing rotating body 133 is splined to the outer periphery of the rotating body 135. That is, in the creep transmission device 33, the reduction shaft 130, the second reduction gear 71B, and the third reduction gear 72A are detachably attached to the third case 23 in a unitized state as the first unit 33A. . Further, the third case 23 is in a state where the fourth reduction gear 72B, the first meshed rotating body 131, the second meshed rotating body 132, the meshing rotating body 133, the rotating body 135, and the like are unitized as the second unit 33B. Is detachably provided.

  FIG. 14 shows another embodiment of the creep transmission device 33 that is different from the above-described creep transmission device 33 in the configuration relating to the first reduction gear 71A of the reduction mechanism 69 and the first meshed rotating body 131 of the switching mechanism 70. Yes.

  In the creep transmission device 33 shown in FIG. 14, the first reduction gear 71 </ b> A of the reduction mechanism 69 is configured to rotate integrally with the third transmission shaft 53 while being allowed to move in the axial direction with respect to the third transmission shaft 53. Is disposed on the third transmission shaft 53. The first reduction gear 71A of the reduction mechanism 69 and the first meshed rotating body 131 of the switching mechanism 70 are integrally formed.

  Thereby, compared with the case where the 1st reduction gear 71A and the 1st to-be-engaged rotary body 131 are formed independently, simplification of the structure by reduction of a number of parts, etc. can be achieved.

  In the creep transmission device 33 shown in FIG. 14, the speed reduction mechanism 69 and the switching mechanism 70 are configured such that the first speed reduction gear 71 </ b> A and the first meshed rotating body 131 are connected with the connection between the second case 22 and the third case 23. The first reduction gear 71 </ b> A and the first meshed rotating body 131 are arranged on the shaft of the third transmission shaft 53, and the first reduction gear 71 </ b> A and the first meshed rotating body 131 are connected to the third transmission shaft 53 as the second case 22 and the third case 23 are disconnected. The entire reduction mechanism 69 and the entire switching mechanism 70 are assembled to the third case 23 together with the first transmission shaft 68 so as to be removed from the shaft.

  Accordingly, when the creep transmission device 33 is assembled to the T / M case 14, the speed reduction mechanism 69 and the switching mechanism 70 are moved together with the first transmission shaft 68 from the split end side of the third case 23 with the second case 22. It can be assembled to the third case 23. Then, after this assembly, the second case 22 and the third case 23 are connected so that the first reduction gear 71A and the first meshed rotating body 131 are arranged on the third transmission shaft 53. The speed reduction mechanism 69 and the switching mechanism 70 can be assembled to the T / M case 14 in a state that spans the third transmission shaft 53 and the first transmission shaft 68. That is, the creep transmission device 33 can be easily assembled in a state extending between the third transmission shaft 53 and the first transmission shaft 68 inside the T / M case 14.

  Further, when removing the creep transmission device 33 from the T / M case 14, the second case 22 and the third case 23 are separated by releasing the connection between the second case 22 and the third case 23. The first reduction gear 71A and the first meshed rotating body 131 can be removed from the axis of the third transmission shaft 53, and the entire reduction mechanism 69 and the entire switching mechanism 70 are moved together with the first transmission shaft 68 and the like. Three cases 23 can be left. Then, the speed reduction mechanism 69 and the switching mechanism 70 remaining in the third case 23 can be detached from the third case 23 together with the first transmission shaft 68 and the like from the split end side of the third case 23 with the second case 22. . That is, it is possible to easily remove the creep transmission device 33 from the T / M case 14, thereby facilitating maintenance of the creep transmission device 33.

  In the creep transmission device 33, like the above-described creep transmission device 33, the reduction shaft 130, the second reduction gear 71B, and the third reduction gear 72A are unitized as a first unit 33A. Three cases 23 are detachably provided (see FIGS. 2 and 7). On the other hand, in the creep transmission device 33, unlike the above-described creep transmission device 33, the first reduction gear 71A, the fourth reduction gear 72B, the first meshed rotating body 131, and the second meshed rotating body 132 are meshed and rotated. The body 133, the rotating body 135, and the like are detachably attached to the third case 23 in a unitized state as the second unit 33B.

  As shown in FIGS. 2 to 3 and FIGS. 6 to 7, the main transmission 32 and the auxiliary transmission 34 are arranged in the T / M case 14 so that the main transmission 32 is arranged on the upper side in the transmission direction. 34 is arranged on the lower side in the transmission direction. When the T / M case 14 is divided into a second case 22 on the upper side in the transmission direction provided with the main transmission 32 and a third case 23 on the lower side in the transmission direction provided with the auxiliary transmission 34, the third case 22 An opening 136 is formed at the front end of the third case 23, which is a split end with the second case 22. In the auxiliary transmission 34, the output gear set 79 described above is replaceably disposed at the foremost position of the auxiliary transmission 34 close to the opening 136 of the third case 23.

  As a result, in this tractor, the output gear set 79 is replaced with another output gear set 79 having a different gear ratio, so that the maximum vehicle speed of the tractor can be easily changed to a vehicle speed suitable for the work mode performed by the user. can do. Then, the output gear set 79 is easily exchanged from the opening 136 of the third case 23 exposed when the T / M case 14 is divided into the second case 22 and the third case 23 for the exchange. be able to. In other words, the maximum vehicle speed of the tractor can be easily changed to a vehicle speed suitable for the work mode performed by the user by a simple replacement operation of the output gear set 79 performed from the opening 136 of the third case 23.

  By the way, as described above, the T / M case 14 is configured to be divided into the second case 22 on the upper side in the transmission direction and the third case 23 on the lower side in the transmission direction at the location where the creep transmission device 33 is disposed. Has been. The creep transmission device 33 is assembled at a position on the opening side in the third case 23 that is located adjacent to the output gear set 79 with the second support wall 29 interposed therebetween. The creep transmission device 33 is detachably attached to the third case 23 in a state where substantially the whole or the whole is unitized into the first unit 33A and the second unit 33B.

  Thereby, when the output gear set 79 is replaced, first, the connection between the second case 22 and the third case 23 in the T / M case 14 is released, and the second case 22 and the third case 23 are separated. . Next, the first unit 33A and the second unit 33B of the creep transmission device 33 arranged on the opening side of the third case 23 are removed from the opening 136 of the third case 23 exposed by this separation, and then the first 2 By removing the support wall 29, it is possible to exchange the output gear set 79 from the opening 136 of the third case 23. Then, by changing the output gear set 79 from the opening 136 of the third case 23, the maximum vehicle speed of the tractor can be easily changed to a vehicle speed suitable for the work mode performed by the user.

  In other words, while the creep transmission 33 is arranged at the T / M case 14 where the second case 22 and the third case 23 are divided, the output gear set 79 is exchanged from the opening 136 of the third case 23. The maximum vehicle speed of the tractor can be easily changed to a vehicle speed suitable for the work mode performed by the user.

[Another embodiment]
The present invention is not limited to the configuration exemplified in the above-described embodiment, and typical other embodiments relating to the present invention will be exemplified below.

[1] The work vehicle transmission includes a work multi-plate clutch (PTO clutch) 87 provided in the work power switching device (transmission switching device) 44, and each transmission switching device 31, 32, 44, 81, All the multi-plate clutches 45, 46, 60 to 63, 66, 67, 84, 86, 87 provided in 82 may have the same radial size.

[2] Each transmission switching device 31, 32, 44, 81, 82 has a radial size of each of the multi-plate clutches 45, 46, 60 to 63, 66, 67, 84, 86, 87, and the load condition is The same size may be set with a size smaller than the size suitable for the most severe multi-plate clutch 66.

[3] The configuration of the main transmission 32 can be variously changed. For example, the main transmission 32 may be configured as a 12-speed transmission having six multi-plate clutches for six-speed transmission and two multi-plate clutches 66 and 67 for two-speed transmission. Alternatively, an 18-speed transmission type having six multi-plate clutches for six-speed shifting and three multi-plate clutches for three-speed shifting may be used.

[4] The work power switching device (transmission switching device) 44 may be configured to have a multi-plate clutch for shifting the work power.

[5] The drive switching device 81 for driving the front wheels and the drive switching device 82 for increasing the front wheels may be integrated into a unit.

  The present invention relates to a transmission for a work vehicle including a plurality of transmission switching devices configured in a multi-plate clutch type in which a transmission state is switched by an intermittent operation of the multi-plate clutch, a tractor including the transmission for the work vehicle, and a mowing machine. It can be applied to work vehicles such as machines, combine harvesters, rice transplanters, and transport work vehicles.

3 Work vehicle transmission 16 Output shaft (for front wheels)
31 Transmission switching device (forward / reverse switching device)
32 Transmission switching device (main transmission)
44 Transmission switching device (work power switching device)
45 Multi-plate clutch (For advance)
46 Multi-plate clutch (for reverse)
60 Multi-plate clutch (for 1-speed)
61 Multi-plate clutch (for 2nd gear)
62 Multi-plate clutch (for 3rd speed)
63 Multi-plate clutch (for 4-speed)
66 Multi-plate clutch (for low speed)
67 Multi-plate clutch (for high speed)
81 Transmission switching device (drive switching device for front wheel drive)
82 Transmission switching device (drive switching device for front wheel speed increase)
84 Multi-plate clutch (for constant speed)
86 Multi-plate clutch (for speed increase)
87 Multi-plate clutch (PTO)
92 Clutch plate 96 Clutch housing (for FR)
97 Clutch housing (1st speed, 2nd speed)
98 Clutch housing (for 3rd speed and 4th speed)
99 Clutch housing (for height)
100 Clutch hub (for FR)
101 Clutch hub (for 1st and 2nd gear)
102 Clutch hub (for 3rd and 4th gear)
103 Clutch hub (for height)

Claims (11)

A plurality of transmission switching devices configured in a multi-plate clutch type in which the transmission state is switched by the intermittent operation of the multi-plate clutch,
The plurality of transmission switching devices are work vehicle transmissions in which the multi-plate clutch provided in all of them is set to have the same radial size.   The plurality of transmission switching devices are set to have the same size in the radial direction of the multi-plate clutch provided in all of them, which is suitable for the multi-plate clutch in which the load conditions are most severe. The work vehicle transmission according to claim 1.   As the plurality of transmission switching devices, forward / reverse switching devices having two multi-plate clutches for forward and reverse, four multi-plate clutches for four-speed shifting, and two multi-plates for two-speed shifting The work vehicle transmission according to claim 1, further comprising an eight-speed main transmission having a clutch.   3. The forward / reverse switching device having two forward and backward multi-plate clutches and the working power switching device having a working multi-plate clutch as the plurality of transmission switching devices. A transmission for a work vehicle as described in 1.   The work vehicle transmission according to claim 3 or 4, further comprising a drive switching device for driving front wheels having a multi-plate clutch for constant speed transmission as the transmission switching device.   6. The work vehicle transmission according to claim 5, further comprising a front wheel speed increasing drive switching device having a multi-plate clutch for speed increasing power transmission as the power transmission switching device.   7. The work vehicle transmission according to claim 6, wherein the front wheel drive switching device and the front wheel speed increasing drive switching device are individually unitized.   The work vehicle transmission according to claim 6 or 7, wherein the front wheel speed increasing drive switching device is detachable.   9. The work vehicle transmission according to claim 8, further comprising a front wheel output shaft that can be used in each of a mounting specification in which the front wheel speed increasing drive switching device is mounted and a non-mounting specification in which the driving switching device is not mounted.   The transmission for a work vehicle according to any one of claims 1 to 9, wherein each of the plurality of transmission switching devices has a length in which each of the clutch hub and the clutch housing allows the extension of the clutch plate. .   A work vehicle comprising the work vehicle transmission according to any one of claims 1 to 10.

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