JP2005306180A - Transmission of working vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transmission for a working vehicle equipped with a compactly structured auxiliary speed change mechanism. <P>SOLUTION: The transmission of the working vehicle is equipped with a running drive shaft 16 to output a running driving force and a rotary drive shaft 17 to output rotary driving force, and structured so that an auxiliary speed change shaft 36 to bear gears 43 and 44 for auxiliary transmission of the running driving force and an operating tool 62 to change over the auxiliary transmission on the axis of the auxiliary speed change shaft 36 are installed in a transmission case 1 in which a running speed change mechanism to make main speed change of the running driving force and a rotary speed change mechanism to make speed change of the rotary driving force are housed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a transmission for a work vehicle having a transmission case in which a travel drive shaft that outputs travel drive force and a rotary drive shaft that outputs rotary drive force protrude.

Conventionally, a transmission case for a tiller in which a traveling drive shaft that outputs a traveling drive force and a rotary drive shaft that outputs a rotary drive force protrude is known (see, for example, Patent Document 1, particularly FIG. 7).
Japanese Patent No. 2660324

  The transmission case houses a traveling speed change mechanism that changes the main driving force and a rotary speed change mechanism that changes the rotary driving force. For this reason, there is little empty space in the mission case, and it is not easy to provide a subtransmission mechanism in the mission case, and it is necessary to prepare another mission case for a tiller that requires the subtransmission mechanism. There was a drawback.

  In order to solve the above problems, a transmission for a work vehicle according to the present invention includes a traveling drive force in a transmission case 16 including a travel drive shaft 16 that outputs a travel drive force and a rotary drive shaft 17 that outputs a rotary drive force. A sub-transmission shaft for supporting sub-shift gears 43 and 44 for driving driving force in a transmission case 1 in a transmission housing a traveling transmission mechanism for main shifting and a rotary transmission mechanism for shifting rotary driving force. 36 and an operation tool 62 for performing a sub-shift switching operation on the axis of the sub-transmission shaft 36 are provided, and the sub-transmission mechanism is integrally configured in the transmission case 1.

  According to the structure of the present invention configured as described above, the auxiliary transmission operating tool is provided on the axis of the auxiliary transmission shaft, so that the auxiliary transmission mechanism can be made compact. As a result, a transmission transmission case that does not have a conventional auxiliary transmission mechanism can be easily installed in a transmission case that has a small internal space and has a traveling drive transmission system and a rotary drive transmission system. Can be used as a transmission case for a transmission with an auxiliary transmission mechanism, and there is an effect that it is not necessary to increase the number of types of transmission cases.

  1 and 2 are a side view and a plan view of a walking type tiller employing the present invention. The mission case 1 constitutes a part of the body frame, and the engine 3 is attached via a bracket 2 attached to the mission case 1. In the mission case 1, a traveling wheel 4 is supported on the front side, and a rotary 6 is supported on the rear side.

  In the transmission case 1, a travel transmission mechanism that shifts the travel drive force for the travel wheels 4, a sub-transmission mechanism that sub-shifts the travel drive force, and a rotary transmission mechanism that shifts the rotary drive force for the rotary 6 are provided. A transmission equipped with is configured. The driving force from the engine 3 is transmitted to the transmission by the main clutch so that it can be turned on and off, the traveling wheels 4 are driven to shift by the traveling transmission mechanism and the auxiliary transmission mechanism, and the rotary 6 is driven to shift by the rotary transmission mechanism.

  A handle 8 is attached to the mission case 1 rearward via a bracket 7. The handle 8 is provided with a clutch operation lever 9 for operating the main clutch on and off so as to be swingable back and forth. The driving of the traveling wheel 4 and the rotary 6 can be turned on and off by the clutch operating lever 9.

  From the mission case 1, a main operation lever for operating the main speed change of the running speed and the drive speed change of the rotary is projected from the rear. The main operation lever 11 protrudes rearward through a lever guide 12 shown in FIG. The main operation lever 11 can be swung back and forth and left and right along the lever guide 12.

  By moving the main operation lever 11 to the left and right, the traveling wheel 4 can be main-shifted in two forward speeds and one reverse speed. By rotating the main operation lever 11 back and forth, the rotary 6 can be shifted in two stages of high speed and low speed. The speed change operation of the rotary 6 can be performed only at the neutral position between the first forward speed and the reverse speed and the first forward speed by the restriction of the lever guide 12.

  The rotary 6 can be driven when the main cultivator is driven at the first main speed. Note that the engine 3 of the walking type tiller can be started only at a neutral position between the first forward speed and the second forward speed of the main control lever.

  On the other hand, on the side of the clutch operation lever 9, a sub transmission lever 13 for operating the sub transmission mechanism is provided. The auxiliary transmission lever 13 and the clutch operation lever 9 are inserted through the same lever guide 14 shown in FIG. 4, and both the levers 9 and 13 can swing back and forth. The traveling wheel 4 can be sub-shifted in two steps by swinging the sub-transmission lever 13 back and forth.

  With the structure shown above, the operator holds the handle 8, engages and operates the main clutch with the clutch operating lever 9, and swings the main operating lever 11 to the left and right to move the main speed at the first speed, the second speed, and the reverse. This walking type tiller can be driven. At this time, the traveling speed can be further sub-shifted in two stages by the forward / backward swing operation of the sub-transmission lever 13.

  Then, the main operating lever 11 is swung up and down from neutral to drive the rotary 6 at high speed or low speed, and to swing at the main speed 1st speed, thereby causing the walking type tiller to run at the main speed 1st speed. However, the rotary 6 can be driven at a high speed or a low speed to perform the tilling work in the field.

  As shown in FIG. 5, the mission case 1 is divided into two forks on the lower side in a side view. An axle 16 protrudes from the front side of the fork and a rotary drive shaft 17 protrudes from the rear side to the left and right. The traveling wheel 4 is supported on the left and right axles 16, and the rotary 6 is supported on the left and right rotary drive shafts 17.

  From the transmission case 1, a travel shifter shaft 18 for shifting the travel (axle 16) and a rotary shifter shaft 19 for shifting the rotary drive shaft 17 protrude. The travel shifter shaft 18 and the rotary shifter shaft 19 are connected to the main operation lever 11. The travel shifter shaft 18 and the rotary shifter shaft 19 are slid by the left / right and forward / backward swing operation of the main operation lever 11, the drive speeds of the axle 16 and the rotary drive shaft 17 are changed, and the main shift of the drive and the shift of the rotary 6 are changed. Is done.

  As shown in FIGS. 6 and 7, the transmission case 1 is supported by an input shaft 21 to which a driving force from the engine 3 is input. An input pulley 20 for driving force is attached to the input shaft 21 outside the mission case 1. A belt tension clutch is provided as the main clutch between the input pulley 20 and the pulley on the engine side. The belt tension clutch is operated by the clutch operating lever 9.

  In the transmission case 1, a rotary speed change gear in which a small-diameter low-speed gear 22 and a large-diameter high-speed gear 23 are integrally formed and a traveling main speed change gear 24 are integrally rotated in the transmission case 1. It is pivotally supported.

  In the transmission case 1, a relay shaft 26 that relays the output from each gear 22, 23, 24 provided on the input shaft 21 is pivotally supported. In the transmission case 26, a reverse transmission gear 27 that transmits the driving force from the gear 24 while reversing the rotation direction is supported in the transmission case 1 so as to rotate integrally with the relay shaft 26. A relay transmission gear 28 is integrally formed with the reverse transmission gear 27. A travel relay output gear 29 is pivotally supported at the end of the relay shaft 26 so as to rotate integrally with the relay shaft 26.

  In the transmission case 1, the relay shaft 26 includes a high-speed relay gear 31 that can mesh with the high-speed gear 23, a low-speed relay gear 32 that can mesh with the low-speed gear 22, and a rotary relay output gear. 33 is pivotally supported so as to be freely rotatable. The high-speed relay gear 31, the low-speed relay gear 32, and the rotary relay output gear 33 are integrally formed, and a needle bearing 34 is provided between the relay shaft 26.

  The transmission case 1 is supported by an auxiliary transmission shaft 36 and an auxiliary transmission output shaft 37 that constitute an auxiliary transmission mechanism. The auxiliary transmission shaft 36 is a stepped shaft composed of a small-diameter solid shaft and a large-diameter hollow shaft. The end of the large diameter shaft 35 (hollow shaft) is open. In the transmission case 1, an input gear 39 is provided at a step portion between the large-diameter shaft 35 and the small-diameter shaft 38 (solid shaft) so that the input gear 39 rotates integrally with the small-diameter shaft 38. The input gear 39 meshes with the travel relay output gear 29 and can mesh with the gear 24 described above.

  In the transmission case 1, a gear in which a large-diameter relay input gear 41 and a small-diameter relay output gear 42 are integrated is freely rotated at an end portion of the large-diameter shaft 35 on the stepped portion side with the small-diameter shaft 38. It is supported freely. The relay output gear 42 meshes with the relay transmission gear 28 of the relay shaft 26 described above. The relay input gear 41 can be engaged with the gear 24 described above.

  Two auxiliary transmission gears 43 and 44 on the low speed side and the high speed side are pivotally supported on the large diameter shaft 35. Both the sub-transmission gears 43 and 44 are switched by a switching mechanism, which will be described later, so that either one selectively rotates integrally with the large-diameter shaft 35.

  Gears 46 and 47 that mesh with the auxiliary transmission gears 43 and 44 are pivotally supported on the auxiliary transmission output shaft 37 so as to rotate integrally. A sprocket 48 that rotates integrally with the auxiliary transmission output shaft 37 is supported between the gears 46 and 47 of the auxiliary transmission output shaft 37. The sprocket 48 transmits driving force to the axle 16 via a chain 49.

  The aforementioned gear 24 can mesh with the reverse transmission gear 27, the input gear 39, or the relay input gear 41 by sliding. For this reason, a main shift of two forward speeds and one reverse speed is performed by meshing with any of the gears 27, 39, and 41. The sub-transmission mechanism can perform a two-stage sub-transmission by outputting a driving force from one of the two sub-transmission gears 43 and 44.

  As described above, the transmission can perform a shift of 4 forward speeds (2 main shift speeds × 2 sub shift speeds) and 2 reverse speeds (1 main shift speed × 2 sub shift speeds). The first forward speed is driven by the auxiliary transmission output shaft 37 in the order of gear 24 → relay input gear 41 → relay output gear 42 → relay transmission gear 28 → running relay output gear 29 → input gear 39 → sub transmission gear 43 → gear 46. Transmit power.

  The second forward speed is driven by the auxiliary transmission output shaft 37 in the order of gear 24 → relay input gear 41 → relay output gear 42 → relay transmission gear 28 → running relay output gear 29 → input gear 39 → sub transmission gear 44 → gear 47. Transmit power.

  In the third forward speed, the driving force is transmitted to the sub-transmission output shaft 37 in the order of gear 24 → input gear 39 → sub-transmission gear 43 → gear 46. The fourth forward speed transmits the driving force to the sub-transmission output shaft 37 in the order of gear 24 → input gear 39 → sub-transmission gear 44 → gear 47.

  In the first reverse speed, the driving force is transmitted to the sub-transmission output shaft 37 in the order of gear 24 → reverse transmission gear 27 → travel relay output gear 29 → input gear 39 → sub-transmission gear 43 → gear 46. In the second reverse speed, the driving force is transmitted to the auxiliary transmission output shaft 37 in the order of the gear 24 → the reverse transmission gear 27 → the traveling relay output gear 29 → the input gear 39 → the auxiliary transmission gear 44 → the gear 47.

  On the other hand, a rotary output shaft 40 is supported in the mission case 1. A gear 45 is pivotally supported on the rotary output shaft 40 so as to rotate integrally. The gear 45 meshes with the rotary relay output gear 33 described above. A sprocket 50 that rotates integrally is pivotally supported on the rotary output shaft 40. The sprocket 50 transmits a driving force to the rotary drive shaft 17 via the chain 60.

  The high speed driving of the rotary 6 transmits a driving force to 40 in the order of the high speed gear 23 → the high speed relay gear 31 → the rotary relay output gear 33 → the gear 45. The low speed driving of the rotary 6 transmits the driving force to 40 in the order of the low speed gear 22 → the low speed relay gear 32 → the rotary relay output gear 33 → the gear 45.

  A switching mechanism in the auxiliary transmission mechanism will be described. As shown in FIG. 8, the switching mechanism includes a compression spring 51, a switching shaft 52, a switching ball 53, an operation shaft 54, and a retaining ball 56 that are accommodated in the large-diameter shaft 35 of the auxiliary transmission shaft 36. The switching shaft 52 is a stepped shaft with both ends having a large diameter and an intermediate portion having a small diameter.

  The large diameter portion and the small diameter portion of the switching shaft 52 are smoothly connected by a tapered surface. The switching shaft 52 has a recess formed by a small diameter portion and a large diameter portion, and slides in the large diameter shaft 35 in the axial direction concentrically with the axis of the auxiliary transmission shaft 36.

  As shown in FIG. 9A, the large-diameter shaft 35 is provided with a plurality of ball holes 57 in the circumferential direction through which the switching balls 53 can be inserted in portions facing the both sub-transmission gears 43 and 44. . Each ball hole 57 is connected to the inside of the hollow and is opened on the peripheral surface of the large-diameter shaft 35. The switching shaft 52 is disposed at a position corresponding to each ball hole 57.

  The switching ball 53 is inserted into each ball hole 57. The switching ball 53 is in contact with the peripheral surface of the switching shaft 52. In a state where the switching ball 57 is in contact with the concave portion (small diameter portion) of the switching shaft 52, the switching ball 53 does not protrude from the peripheral surface of the large diameter shaft 35. When the switching ball 53 comes into contact with the large diameter portion of the switching shaft 52, the switching ball 53 protrudes from the peripheral surface of the large diameter shaft 35.

  As shown in FIG. 9B, each sub-transmission gear 43 and 44 is provided with an engagement recess 58 for each switching ball 57 into which a switching ball 53 protruding from the peripheral surface of the large-diameter shaft 35 is fitted. ing. The auxiliary transmission gears 43, 44 rotate integrally with the large-diameter shaft 35 (sub-transmission shaft 36) when the switching ball 53 protrudes from the peripheral surface of the large-diameter shaft 35 and the switching ball 53 fits into the engaging recess 58.

  The switching shaft 52 slides on the axis of the auxiliary transmission shaft 36, thereby causing the switching ball 53 to protrude from the peripheral surface of the large-diameter shaft 35 with respect to any one of the auxiliary transmission gears 43 or 44. The auxiliary transmission gear 43 or 44 on the side from which the gear is protruded is rotated integrally with the auxiliary transmission shaft 36.

  The switching mechanism is configured to selectively rotate one of the auxiliary transmission gears 43 or 44 integrally with the auxiliary transmission shaft 36 by sliding the switching shaft 52 as described above. For this reason, a compression spring 51 is provided between the switching shaft 52 and the end surface of the hollow portion to urge the switching shaft 52 toward the opening side of the hollow portion and to contact the end surface of the switching shaft 52 opposite to the compression spring 51. The operation shaft 54 is inserted into the hollow portion, and the switching shaft 52 is positioned by the operation shaft 54.

  In the initial state, the switching ball 53 on the low speed side sub-transmission gear 43 is in contact with the large-diameter portion of the switching shaft 52, and the switching ball 57 is fitted in the engagement recess 58 of the low-speed side sub transmission gear 43. A low speed of sub-transmission where the transmission gear 43 rotates integrally with the sub-transmission shaft 36 is set.

  When the operating shaft 54 is pushed in from the initial state, the switching shaft 52 is pushed against the urging force of the compression spring 51, and the switching ball 53 engaged with the low-speed auxiliary transmission gear 43 side is turned on. The engagement between the low-speed side auxiliary transmission gear 43 and the switching ball 53 is released.

  Then, the switching ball 53 on the high-speed side sub-transmission gear 44 side contacts the large-diameter portion of the switching shaft 52, and the switching ball 53 is fitted in the engagement recess 58 of the high-speed side sub-transmission gear 44. Rotates integrally with the auxiliary transmission shaft 36, and the auxiliary transmission is switched to the high speed side.

  The switching mechanism is configured as described above, and the sub-transmission mechanism is switched to the low speed side in the initial state, and switched to the high speed side by pushing the operating shaft 54. When the pushing of the operating shaft 54 is released, the initial state is restored by the urging force of the compression spring 51 and the operation shaft 54 is switched to the low speed side. The operation shaft 54 is operated by the auxiliary transmission lever 13 through an operation mechanism as will be described later.

  Similar to the switching shaft 52, the operating shaft 54 is a stepped shaft having a large diameter at both ends and a small diameter at the middle portion. The large diameter portion and the small diameter portion of the operation shaft 54 are smoothly connected by a tapered surface. The operation shaft 54 has a recess 55 formed by a large diameter portion and a small diameter portion.

  As shown in FIG. 9C, the large-diameter shaft 35 of the auxiliary transmission shaft 36 is provided with a ball hole 59 into which a retaining ball 56 can be inserted at a position corresponding to the operation shaft 54. The ball hole 59 is connected to the hollow interior and is open on the peripheral surface of the large-diameter shaft 35. The retaining ball 56 does not protrude from the peripheral surface of the operation shaft 54 when in contact with the recess 55 (small diameter portion) of the operation shaft 54.

  The retaining ball 56 protrudes from the peripheral surface of the operation shaft 54 when it comes into contact with the large diameter portion of the operation shaft 54. However, a collar 61 is fitted on the operation shaft 54 so as to close the opening of the ball hole 59. For this reason, the collar 61 restricts the retaining ball 56 from protruding from the peripheral surface of the operation shaft 54, and the operation shaft 54, the switching shaft 52, the switching ball 57, and the compression spring 51 are prevented from coming off from the auxiliary transmission shaft 36. The

  That is, the retaining ball 56 and the recess 55 of the operation shaft 54 can easily constitute a retaining mechanism for the switching mechanism including the operation shaft 54 and the switching shaft 52. As a result, the operating shaft 54 can slide within the range of the length of the concave portion 55, and the auxiliary transmission mechanism of the auxiliary transmission mechanism is slid by sliding along the axis of the auxiliary transmission shaft 36 of the operating shaft 54 and the switching shaft 52 within this range. Switching operation is easily performed.

  Since the retaining mechanism is composed of the balls as described above, the operation shaft 54 is smoothly slid by the retaining balls 56. The collar 61 is fixed in position by a bearing 63 that supports the auxiliary transmission shaft 36 (large diameter shaft 35), and the assembling property of the retaining mechanism is high.

  The sub-transmission mechanism and the switching mechanism are configured as described above. In particular, since the switching mechanism is configured in the sub-transmission shaft 36 and on the axis of the sub-transmission shaft 36, the sub-transmission mechanism becomes compact, and the sub-transmission mechanism The auxiliary transmission shaft 36 and the auxiliary transmission output shaft 37 are sufficient for the shaft space in the transmission case 1. As a result, as described above, the sub-transmission mechanism can be easily provided in the mission case 1 having a small internal space including the travel drive transmission system and the rotary drive transmission system.

  For this reason, in addition to being able to easily add a subtransmission mechanism to a transmission that does not have a conventional subtransmission mechanism, a transmission mission case that does not have a conventional subtransmission mechanism can be used as a transmission mission with a subtransmission mechanism. It can be shared as a case, and there is no need to increase the types of mission cases for walking type tillers.

  In particular, the switching shaft 52 and the operation shaft 54 having the same axis as the auxiliary transmission shaft 36 constitute an operation tool 62 for performing an operation for changing the auxiliary transmission, and the switching mechanism is arranged on the axis of the auxiliary transmission shaft 36. Since the shift switching operation is performed, the configuration of the switching mechanism is compact, and there is no need to separately support the auxiliary shift switching shaft in the transmission case 1.

  The operating tool 62 is divided into a switching shaft 52 for performing a shift operation and an operating shaft 54 for operating the switching shaft 52. The switching shaft 52 and the operating shaft 54 have large diameter shafts 35 at the large diameter portions at both ends. Since the slide portion slides in contact with the hollow portion, the slide portion slides in a both-side supported state, and the slide is smooth and the play of the switching shaft 52 and the operation shaft 54 is reduced. At this time, the shaft and the hole are processed and fitted to each other with relatively high accuracy, so that the sliding operation of the switching shaft 52 and the operation shaft 54 is accurate and stable, and the sub-shift switching is performed accurately.

  The operation mechanism for sub-shift switching will be described. As shown in FIGS. 10 and 11, the operation shaft is located between the input pulley 20 and the transmission case 1 at a position corresponding to the end of the large-diameter shaft 35 of the auxiliary transmission shaft 36 of the transmission case 1. A switching link mechanism 71 for performing a pushing operation of 54 is provided. The switching link mechanism 71 has a structure in which a link arm 72 composed of two plates is pivotally supported by a plate 73 bolted to the transmission case 1 via a fulcrum shaft 74.

  The link arm 72 and the above-described auxiliary transmission lever 13 are connected via a wire 76. A pin 77 is inserted into the operation shaft 54. The pin 77 is inserted into a long hole 78 provided in the link arm 72. As the link arm 72 swings, the operation shaft 54 is pushed in and released.

  The link arm 72 is driven to swing through the wire 76 in response to the swing operation of the auxiliary transmission lever 13. When the wire 76 is pulled, the operation shaft 54 is pushed by the link arm 72 and the sub-shift is switched to the high speed side. When the wire 76 is loosened, the push of the operation shaft 54 by the link arm 72 is released, and the urging force of the compression spring 51 As a result, the sub-transmission returns to the low speed side.

  The operation of the wire 76 is performed by the auxiliary transmission lever 13, and the auxiliary transmission is switched as described above. The sub-transmission switching operation mechanism is configured simply as described above, and the operation mechanism can be configured in a small space between the input pulley 20 and the transmission case 1.

  Further, when the pin 77 and the link arm 72 are engaged through the long hole 78, the operation shaft 54 is prevented from rotating, and the shafts 52 and 54 are divided and not integrated. Even when the auxiliary transmission gear 43 or 44 is rotated, the operation shaft 54 is prevented from being rotated, the movement on the switching shaft 52 side is not transmitted to the operation shaft 54 side, and the auxiliary transmission lever via the operation shaft 54 is prevented. 13 can be performed smoothly and stably.

  On the other hand, when the number of gears and the gear meshing structure are different, a gear 64 can be provided at the position of the collar 61 via a needle bearing 65 instead of the collar 61 as shown in FIG. In this case, it is not necessary to dispose the gear 64 at another position of the auxiliary transmission shaft 36, the gear 64 can be disposed in a small space, and the gear 64 and the needle bearing 65 are also used as a retaining mechanism for the operation shaft 54. can do.

  The needle bearing 65 prevents the gear 64 from being rotated. Further, a structure in which another rotating body or the like is pivotally supported instead of the gear 64 can be provided, and in this case, the same effect as described above can be obtained.

  As shown in FIG. 13, one operation switching shaft 66 in which the switching shaft 52 and the operation shaft 54 are integrated is inserted into the hollow portion of the large-diameter shaft 35, and the sub-shift is switched by the operation switching shaft 66. You may comprise. In this case, instead of the recess 55 of the operation shaft 54, a groove 67 may be provided in a part of the peripheral surface, and the retaining ball 56 may be positioned in the groove 67.

  As a result, the operation switching shaft 66 is prevented from coming off by the groove 67 and the retaining ball 56, and the rotation of the operation switching shaft 66 is restricted by the groove 67 and the retaining ball 56. The rotation with 43 or 44 is prevented. And the number of parts can be reduced.

It is a side view of a walking type tiller. It is a top view of a walking type tiller. It is a top view of the lever guide of a main operation lever. It is a top view of the lever guide of a sub transmission lever and a clutch operation lever. It is a side view of a mission case. FIG. 2 is a developed cross-sectional view of a transmission case mainly showing a shift structure of a traveling system. FIG. 3 is a developed cross-sectional view of a transmission case mainly showing a rotary transmission structure. It is principal part sectional drawing of a mission case. (A) is sectional drawing of the ball hole part of the switching ball of a large diameter shaft, (b) is sectional drawing of an auxiliary transmission gear, (c) is sectional drawing of the ball hole part of the retaining ball of a large diameter shaft. It is a side view of the operation mechanism of subshift switching. It is a top view of the operation mechanism of subshift switching. It is sectional drawing of the auxiliary transmission shaft which supported the gear instead of the collar. It is sectional drawing of the auxiliary transmission shaft which uses the operation switching shaft.

Explanation of symbols

1 Mission case 16 Axle (travel drive shaft)
17 Rotary drive shaft 36 Sub transmission shaft 43 Sub transmission gear (gear)
44 Sub-transmission gear (gear)
62 Operation tool

Claims (1)

In a transmission case (1) having a travel drive shaft (16) for outputting travel drive force and a rotary drive shaft (17) for outputting rotary drive force, a travel transmission mechanism for main shifting the travel drive force, and a rotary In a transmission housing a rotary speed change mechanism for shifting a driving force, a sub-transmission shaft (36) for supporting sub-shift gears (43), (44) for traveling driving force in a transmission case (1) A transmission for a work vehicle in which a sub-transmission mechanism is integrally formed in the transmission case (1) by providing an operation tool (62) for performing a sub-transmission switching operation on the axis of the sub-transmission shaft (36).

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