JP2002144901A - Transmission for tractor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize a transmission for a tractor equipped with a rear PTO shaft and a mid PTO shaft. SOLUTION: The transmission for a tractor comprises a transmission mechanism 43 for taking an input of engine power and changing speed, a front-wheel drive output shaft 19 for outputting power outputted from the transmission mechanism 43 to front wheels, a differential gear 56 for output to a right and a left rear wheel, and the mid PTO shaft 25. A space defined between the differential gear 56 and the mechanism 43 accommodates, in juxtaposition, a first drive train 115 between a clutch mechanism 83 for engaging/disengaging power to the mid PTO shaft 25 and the mid PTO shaft 25, and a second drive train 112 from the transmission mechanism 43 to the front-wheel drive output shaft 19.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tractor transmission.

[0002]

2. Description of the Related Art Conventionally, two PTO shafts, namely, a rear PT
The construction of a tractor transmission having an O-axis and a mid-PTO axis is known. This transmission shifts the power from the engine and transmits the power to the rear axle and the front axle, and also transmits the power from the engine to the two PTO shafts. It is configured to be able to drive a working machine supported on the abdomen of the vehicle body.

[0003]

In such a transmission, it is necessary to arrange the layout of the drive system for the rear axle and the front axle and the layout of the drive system for the two PTO shafts so as not to interfere with each other. It was difficult to make the transmission more compact. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a layout of each drive system that can make a transmission compact.

[0004]

The problems to be solved by the present invention are as described above. Next, means for solving the problems will be described.

That is, in the first aspect, a speed change mechanism for inputting engine power to change the speed, a front wheel drive output shaft for outputting the power output from the speed change mechanism to the front wheels, and a differential for outputting the power to the left and right rear wheels. In a transmission of a tractor including a transmission and a mid-PTO shaft, the mid-PTO is inserted into a space between the differential and the transmission mechanism.
From the clutch mechanism for connecting and disconnecting power to the shaft,
A first drive train leading to the O-axis and a second drive train leading from the speed change mechanism to the front wheel drive take-out shaft are juxtaposed.

According to a second aspect of the present invention, a rear PTO shaft is further provided, and power is supplied to the rear PTO shaft at a rear side of the clutch mechanism.
A PTO power switching mechanism capable of switching between a state where power is transmitted to the TO shaft and a state where power is transmitted to the mid PTO shaft is interposed.

According to a third aspect of the present invention, a clutch mechanism for connecting / disconnecting engine power to / from the shaft is disposed on one side of a shaft constituting an output side of the clutch mechanism. A brake device for applying a braking force to the shaft when the braking is performed is arranged on the other side.

According to a fourth aspect of the present invention, a shaft constituting the transmission mechanism supports some of the gears constituting the first and second drive trains.

[0009]

Next, embodiments of the present invention will be described. FIG. 1 is an overall side view of a tractor provided with the transmission of the present invention. 2 is a side sectional development view of the transmission, FIG. 3 is a plan sectional view of the transmission, and FIG. 4 is a sectional view taken along the line XX in FIG. FIG.
FIG. 3 is a hydraulic circuit diagram of the tractor. FIG. 6 is an enlarged sectional view showing a state in which the brake housing is inserted into the recess of the partition wall and assembled.

[Structure of Tractor] In the agricultural tractor 1 shown in FIG. 1, the left and right vehicle frames 3 along the front-rear direction are arranged, and the front of the transmission case 29 of the transmission 14 is attached to the rear end of the vehicle frame 3. The rear axle case 15 is disposed on the rear left and right side surfaces of the transmission case 29. Reference numeral 2 denotes a transmission cover. A working machine can be connected to the rear of the tractor 1, and a rear PTO shaft 23 for driving the working machine projects from the rear end of the transmission case 29 and is supported. When a work machine such as a mower is supported on the abdomen of the vehicle body, a mid-PTO shaft 25 for driving the work machine is supported by a cover 25a attached to the bottom surface of the transmission case 29 and projects forward. Is done.

A front axle case 12 is supported below the front of the vehicle frame 3, and front wheels 4 are suspended at left and right ends of the front axle case 12. Also,
The rear axle case 15 has a pair of left and right rear axles 15.
a and 15a, and rear wheels 5.5 are attached to outer ends of the rear axles 15a. A lift arm 21 for lifting and lowering the work equipment is provided on the upper rear surface of the transmission case 29.
Is provided.

Steps 6 are provided on both left and right sides of the vehicle frame 3.
・ 6 is arranged almost horizontally. A seat 7 is provided above the transmission 14, and a dashboard 8 is provided upright in the middle of the vehicle frame 3. An instrument panel 11 is provided on the upper surface of the dashboard 8 and a steering handle 9 for steering the front wheels 4.
Is protruding.

A shift lever 41 projects laterally from one of the left and right sides of the dashboard 8 and is supported so as to be able to rotate back and forth while pointing its grip portion substantially in the left-right direction of the body. The link mechanism is linked to a control arm 14d of the transmission 14 described later. A travel stop pedal 47 is pivotally supported on the step 6 on the left side of the machine body, and is linked so that the vehicle can be stopped in a neutral state of the transmission 14 by depressing the travel stop pedal 47. Further, when a PTO clutch mechanism 69 described later is connected, the PTO clutch mechanism 69 is interlocked with the PTO clutch mechanism 69 so as to be disconnected.

In the transmission 14, an auxiliary transmission mechanism and a differential mechanism for driving the left and right rear axles 15a, 15a are disposed, and the auxiliary transmission mechanism is disposed on a side portion of the seat 7 above. The shift can be switched by the shift lever 24. Also, the rear PTO shaft 23 and the mid PTO shaft 2
A mechanism for connecting and disconnecting power to the transmission 5 is also disposed in the transmission 14. The configuration of the transmission 14 will be described later.

With this configuration, the driving force of the engine 26 is input to the transmission 14 and drives the left and right rear wheels 5.5 via a pair of left and right rear axles 15a in the rear axle case 15. Further, a rotation synchronized with the rear axles 15a and 15a is obtained on the front wheel drive take-out shaft 19 supported at the front of the transmission 14, and the rotation of the front wheel drive take-out shaft 19 is transmitted through the propeller shaft 13 and the universal joint to the front. It is transmitted to the axle case 12 and drives the left and right front wheels 4. Also, the rear PTO shaft 23 / mid P supported by the transmission 14
The power of the engine 26 is also transmitted to the TO shaft 25, so that the working machine attached to the vehicle body can be driven.

An engine 26 is supported on the vehicle frame 3 by vibration isolation. A group of devices such as a radiator, a battery, an air cleaner, and a muffler are arranged around the engine 26 (not shown), and these devices are surrounded by a front cover 17, side covers 18, 18 and a hood, as shown in FIG. Covered with 10. The crankshaft of the engine 26 projects rearward and has a flywheel 48 attached thereto. The flywheel 48 is connected via a rubber damper (not shown), two universal joints 50 and 52, and a transmission shaft 51 inclined downward. , And the input shaft 14 b of the transmission 14.

[Configuration of Transmission] Next, the configuration of the transmission of the present invention will be described. As shown in FIGS. 2 and 3, the transmission 14 includes a split transmission case 29 having front and rear case halves 29a and 29b.
A hydrostatic stepless transmission (hereinafter, referred to as "HST") 14a as a main transmission mechanism is provided on a front surface thereof, and an input shaft 14b of the HST 14a projects forward from a housing 14c of the HST 14a. Under the HST 14a, the front wheel drive take-out shaft 19 is
Are projected and supported, and the rear PTO shaft 23 is supported at the rear end of the transmission case 29.

The case half 29a has a wall 90 at the front end and an open rear end. The case half portion 29b has a wall portion 91 at the rear end and an opening at the front end, and has a partition wall 108 at a midway between the front and rear, and has an upper surface of the case half portion 29b behind the partition wall 108 opened. The rear edge of the case half 29a and the front edge of the case half 29b are joined to form a first chamber 131 in front of the partition wall 108 and a second chamber 132 in the rear. I do. Further, a cover 110 is attached to the rear wall 91 of the case half 29b, and the rear wall 91 and the cover 110
And a third chamber 133 is formed. Then, in the first chamber 131, between the front wall 90 of the case half 29a and the partition wall 108 of the case half 29b,
A traveling output shaft 42, a traveling counter shaft 45, a front wheel drive take-out shaft 19, which will be described later in detail, are parallel to each other along the front-rear direction.
The PTO drive main shaft 68 and the first rear PTO transmission shaft 82 are supported by bearings. A second rear PTO transmission shaft 92 and a rear PTO shaft 2, which are parallel to each other along the front-rear direction and are described later, are provided between the rear wall 91 and the cover 110 of the case half 29 b.
3 is supported by bearings.

The inside of the transmission case 29 is filled with a certain amount of oil, which naturally lubricates shafts, gears and the like arranged in a drive system to be described later, and also serves as a working oil for the HST 14a. As shown in FIGS. 3 and 4, two hydraulic pumps 65 and 66 are provided on one side of the transmission case 29.
As shown in FIG. 5, the oil in the transmission case 29 is supplied to the HST 1 by a first hydraulic pump 65.
4a is fed as pressure oil to the hydraulic oil circulation oil passages 20 and 20 and a PTO clutch mechanism 69 described later.
Also, oil is supplied to the power steering device 27 for reducing the operation force of the steering handle 9, and is used as hydraulic oil for both devices 69 and 27. Also, a work implement lifting lever 28 provided at an appropriate position of the vehicle is provided.
The oil in the transmission case 29 is pumped by a second hydraulic pump 66 to a hydraulic lift device 22 that drives the lift arm 21 for lifting and lowering the work implement in accordance with the operation of the work machine, and is used as hydraulic oil. .

[Traveling drive system] The transmission 1
4 will be described. This traveling drive system is
The HST 14a, an auxiliary transmission mechanism 43 for further shifting the output of the HST 14a, a rear wheel drive train 111 for transmitting the rotation shifted by the auxiliary transmission mechanism 43 to a rear axle via a differential device 56, A front wheel drive train 112 for transmitting the rotation shifted by the subtransmission mechanism 43 to the front wheel drive take-out shaft 19.

First, the HST 14a as a main transmission mechanism will be described. A flat center section 30 is mounted upright on a substantially upper half of the front surface of the transmission case 29, and a pump mounting surface is provided on the upper front surface of the center section 30 and a motor mounting surface is provided on the lower front surface thereof. .
The center section 30 includes a hydraulic pump 31 described later.
And an HST housing 14c for housing the hydraulic motor 32.

A hydraulic pump 31 having the following structure is mounted on the pump mounting surface. That is, the input shaft 14b, which is also used as a pump shaft, is supported at the center of the pump attachment surface, and the cylinder block 33 is fitted to the input shaft 14b so as to be relatively non-rotatable. It is installed to be rotatable and slidable on the attachment surface. A plurality of cylinder holes are formed in the cylinder block 33, and a piston 34 is fitted in each of the cylinder holes via an urging spring so as to be slidable reciprocally. The head of the piston group 34 is a movable swash plate 35.
By changing the tilt angle of the movable swash plate 35, the stroke of the piston 34 is changed, and the discharge volume can be changed steplessly. The movable swash plate 35
Is configured as a trunnion type, and the trunnion shaft extends out of the housing 14c to form a control arm 14d.
Is attached (FIG. 3), and the control arm 14d is attached.
Is linked to the shift lever 41 via a link mechanism (not shown).

Also, inside the center section 30,
Hydraulic oil circulation passages 20, 20 are provided for feeding hydraulic oil discharged by the hydraulic pump 31 to a hydraulic motor 32 described below (FIG. 3). Hydraulic motor 32
Will be described. That is, a motor shaft 36 arranged in parallel below the input shaft 14b is supported at the center of the motor mounting surface, and a cylinder block 37 is fitted to the motor shaft 36 so as to be relatively non-rotatable. Is mounted so as to be rotatable and slidable with respect to the motor mounting surface of the center section 30. A plurality of cylinder holes are formed in the cylinder block 37, and a piston 38 is fitted in each of the cylinder holes via an urging spring so as to be reciprocally movable. The head of the pistons 38 is a fixed swash plate 39
The rotation of the motor shaft 36 can be obtained at a speed corresponding to the discharge volume of the hydraulic pump 31.

The motor shaft 36 is connected to the center section 30.
, And protrudes into the rear case half 29a, and the traveling output gear 40 is fixed to the rear end. In the front half of the traveling output shaft 42 and traveling counter shaft 45 in the transmission case 29, a constant mesh type two-stage speed change type auxiliary transmission mechanism 43 is provided.

The structure of the subtransmission mechanism 43 will be described with reference to FIG. A first input gear 44 is loosely fitted on the traveling output shaft 42, and the first input gear 44 is meshed with the traveling output gear 40 on the motor shaft 36. Further, a first counter gear 46 is fixed on the traveling counter shaft 45, and the first input gear 44 is also meshed with the first counter gear 46. A second counter gear 49 having a smaller number of teeth than the first counter gear 46 is formed on the travel counter shaft 45, and the second counter gear 49 is loosely fitted on the travel output shaft 42. The input gear 53 is engaged. Then, at a position sandwiched between the first input gear 44 and the second input gear 53, the travel output shaft 42
A clutch slider 54 is fitted thereon via a clutch hub. The clutch slider 54 is not rotatable relative to the traveling output shaft 42 and is slidable in the axial direction. The clutch slider 54 is linked to the sub shift lever 24. The first input gear 44 and the second input gear 53 are both formed with teeth that can be engaged with a clutch slider 54. The clutch lever 54 is pivoted by operating the sub-transmission lever 24. By sliding in the direction, the high-speed rotation from the first input gear 44 or the reduced rotation of the second input gear 53 can be alternatively obtained on the traveling output shaft 42. It is also possible to set a neutral state in which any rotation is not transmitted.

The rotation input to the travel output shaft 42 is transmitted to the rear wheels 5.5 via the rear wheel drive train 111.
To the front wheels 4.4 via the front wheel side drive train 112,
Each is transmitted.

The rear drive train will be described.
That is, a bevel gear 55 is formed at the rear end of the traveling output shaft 42, and the bevel gear 55 is engaged with an input bevel gear 57 of the differential device 56. The power input to the differential 56 is distributed to the left and right differential output shafts 16 and 16 in torque.
The gears are transmitted to rear axles 15a in the rear axle case 15 via gears to drive the rear wheels 5.5.

The front wheel drive train 112 will be described. A position sandwiched between the auxiliary transmission mechanism 43 and the differential device 56 in the front-rear direction, and a PTO power switching mechanism 8 described later.
3, a front wheel output gear 58 is fixed on the traveling output shaft 42 on the opposite side of the clutch slider 54 from the second input gear 53, and the front wheel output gear 58 An intermediate gear 59 loosely fitted on the counter shaft 45 is engaged. A front wheel transmission gear 60 is provided on the front wheel drive take-out shaft 19 supported below the transmission case 29.
The front wheel transmission gear 60 is meshed with the intermediate gear 59. Further, a clutch device 101 for engaging and disengaging the front wheel drive gear 60 with respect to the front wheel drive take-out shaft 19 is provided on the front wheel drive take-out shaft 19. The clutch device 101 has a spline engraved on the front wheel drive take-out shaft 19, a clutch slider 102 is arranged on the spline so as to be slidable in the axial direction and relatively unrotatable. A tooth portion that can be engaged with the clutch slider 102 is formed and configured. The clutch slider 10
2 is linked to a drive mode switching lever provided at an appropriate position on the vehicle seat of the tractor, and by operating the drive mode switching lever, a rear wheel drive mode in which the power of the engine is transmitted only to the rear wheels 5; The four-wheel drive mode transmitted to the front wheels 4 as well as the wheels 5 can be switched. With this configuration, by setting the drive mode switching lever to the four-wheel drive mode, rotation synchronized with the traveling output shaft 42 is transmitted to the front wheel drive take-out shaft 19, and the front wheels 4 can be driven.

[Hydraulic Pump Drive System] Next, the hydraulic pump 6
The pump drive drive train 113 for driving the motor 5.66 will be described. That is, as shown in FIG. 3, the input shaft 14b penetrates the center section 30 and has an output gear 61 at its rear end. The counter shaft 62 is cantilevered on the front wall 90 of the case half 29a in close proximity to the output gear 61, and the hydraulic pump driving gear 63 is rotatably supported on the counter shaft 62. Are engaged. The hydraulic pump driving gear 63 is further meshed with a transmission gear 64a supported in a pump mounting case 64 fixed to one side wall of the case half 29a.
a is fixed to a common input shaft 67 of two hydraulic pumps 65 and 66 connected to the rear surface of the pump mounting case 64. Therefore, the two hydraulic pumps 65 and 66 are driven by the power of the input shaft 14b, and the oil in the transmission case 29 is pumped to the power steering device 27, the hydraulic lift device 22, and the like.

[PTO drive system] Next, the above-mentioned rear PTO
A drive system for driving the shaft 23 and the mid PTO shaft 25 will be described. As shown in FIG. 3 and FIG.
The PTO drive main shaft 68 is rotatably supported at a position substantially opposite to the hydraulic pump drive gear 63 with the. The P
The TO drive main shaft 68 is disposed at a position offset with respect to the input shaft 14b. On the PTO drive main shaft 68, a hydraulic multi-plate wet type PTO clutch mechanism 6 is provided on one of the front and rear sides.
9 and a hydraulic multi-plate wet type anti-rotation brake device 97 is installed at the other end of the shaft. in this way,
PTO clutch mechanism 69 and anti-rotation brake device 9
By arranging 7 and 7 on one PTO drive spindle 68, the mechanism can be made compact.

The structure of the PTO clutch mechanism 69 will be described. An input gear 70 is rotatably supported on the PTO drive main shaft 68 to mesh with the output gear 61, and a clutch housing 71 having an annular concave portion
It is fixed on the TO drive main shaft 68 so as not to rotate relatively. A piston 72 is provided in the annular concave portion so as to be hydraulically movable.
And one side surface of the input gear 70 is cylindrically extended toward the annular recess to form a boss portion, and a plurality of friction plates attached to an outer periphery of the boss portion and the clutch housing. A friction plate group 81 is configured by alternately laminating a plurality of friction plates attached to 71. The piston 72 presses the friction plate group 81 to frictionally engage the input gear 70 with the clutch housing 71, or releases the pressure contact of the friction plate group 81 to
It is configured so that the frictional engagement of 71 can be released. P
An oil supply / drain passage 73 is formed in the TO drive main shaft 68 in the axial direction, and communicates with an annular concave portion of the clutch housing 71. This is performed by supplying and discharging pressure oil through the supply and discharge oil passage 73.

The structure of the anti-rotation brake device 97 will be described. One end of the PTO drive main shaft 68 faces the inside of the cup-shaped brake housing 103, and is supported via a bearing 109. This brake housing 103
Is inserted in the recess 116 formed on the side face of the partition wall 108 of the case half portion 29b facing the first chamber 131 in the axial direction as shown in FIG. 6 without bolting. , The bearing 10
9. The PTO drive main shaft 68 is supported by the partition wall 108 via the brake housing 103. At least one projection 103a is integrally formed on the outer peripheral surface of the brake housing 103, and an engagement groove 116a that fits with the projection 103a by inserting the brake housing 103 is formed in the recess 116.
The brake housing 103 is fixed to the partition wall 108 in a non-rotatable manner without the need for fastening bolts. A piston 104 is oil-tightly fitted to the end of the PTO drive spindle 68 inserted into the brake housing 103, and a friction plate attached to the brake housing 103 and a friction plate attached to the PTO drive spindle 68 Are alternately laminated to form a friction plate group 106.
And its position is regulated by a retaining ring 117 that is engaged with the brake housing 103. The piston 10
4 presses the friction plate group 106 to frictionally engage the friction plate group 106 to apply a braking force to the PTO drive main shaft 68.

Here, a disc spring 105 is further disposed between the piston 104 and the brake housing 103 to apply an urging force for pressing the friction plate group 106 to the piston 10.
4 given. The oil supply / discharge passage 73 bored in the PTO drive main shaft 68 extends and opens between the end surface of the PTO drive main shaft 68 and the piston 104. Accordingly, when pressure oil is supplied to the oil supply / discharge passage 73, the piston 104 is opposed to the disc spring 105 by the friction plate group 10.
6 is retracted in the direction of releasing the pressure contact of the PTO drive spindle 6.
8 is released, while the pressure oil in the oil supply / drain passage 73 is drained, so that the piston 104
5, the friction plate group 106 frictionally engages with the retaining ring 117 to apply a braking force to the PTO drive main shaft 68.

The configuration of the hydraulic circuit for driving the PTO clutch mechanism 69 and the brake device 97 thus configured will be described mainly with reference to FIG. That is, the strainer 74 is installed at the bottom of the second chamber 132 of the transmission case 29, and the oil filtered by the strainer 74 is supplied to the oil passage 75 formed in the thick wall of the side wall of the case half 29b, the case half, and the like. It is guided to the suction port of the hydraulic pump 65 disposed on one side of the transmission case 29 via a pipe joint 76 attached to the outer wall of the portion 29b. The oil discharged from the discharge port of the hydraulic pump 65 is supplied to the valve unit 9 attached to the other side wall of the case half 29a.
6 is introduced from the pipe joint 77 into the pressure reducing valve 78 which regulates the charge pressure for compensating for the oil leakage of the HST 14a. The oil drained by the pressure reducing valve 78 is sent to a solenoid type PTO on / off valve 79. The PTO on / off valve 79
Is connected to the PTO clutch mechanism 69 and the brake device 97 from the oil passage 80 formed in the front wall 90 of the case half 29a through the supply / discharge oil passage 73 formed in the PTO drive main shaft 68. You. The PTO on / off valve 79 is of an electromagnetic type, and can be artificially switched by an ON / OFF operation of a PTO connection / disconnection switch provided around the driver's seat.

The operation of the above configuration will be described. That is, when the PTO connection / disconnection switch is operated to the “PTO drive” position, the PTO on / off valve 79 supplies pressure oil to the supply / discharge oil passage 73, and the piston 72 of the PTO clutch mechanism 69 presses the friction plate group 81 against the friction plate group 81. At the same time, the piston 104 of the brake device 97 enters a “clutch engagement / brake release” state in which the pressing state of the friction plate group 106 is released, and the power from the engine 26 is supplied to the rear PTO shaft 2 via a PTO switching mechanism described later.
Transmitted to the 3 or mid PTO shaft 25, or both,
Drive the work machine. On the other hand, when the PTO connection / disconnection switch is operated to the “PTO stop” position, the PTO on / off valve 79 drains the pressure oil from the supply / discharge oil passage 73, and the piston 72 of the PTO clutch mechanism 69 presses the friction plate group 81. At the same time, the piston 104 of the brake device 97 enters a “clutch disconnection / brake operation” state in which the friction plate group 106 is pressed, and the power from the engine 26 to the rear PTO shaft 23 and the mid PTO shaft 25 is cut off. Immediately the braking action works to brake the inertial rotation, and the rear PTO
The rotation of the shaft 23 and the mid PTO shaft 25 is prevented.

The HST closed circuit connected from the pressure reducing valve 78 to the hydraulic oil circulation passages 20 of the HST 14a includes a check valve 121 for preventing backflow, a throttle 122 for expanding a neutral range, Relief valve 123 that regulates the operating oil pressure of HST and check valve 1 to prevent freewheel
24 and the like are connected and arranged. The hydraulic oil circulation oil passage 20
The oil drained from the PTO drive main shaft 68 through a lubricating oil passage 89, the friction plate groups 81 and 106 on the PTO drive main shaft 68 and output gears 84 and 8 described below.
After lubricating 6 etc., it is returned to the mission case 29 as an oil reservoir.

Next, the rear P
Rear PTO drive train 114 to TO shaft 23
Will be described. A rear PTO transmission shaft 82 is arranged behind the input shaft 14b of the HST 14a so that the axis thereof coincides with the input shaft 14b. One end of the rear PTO transmission shaft 82 is inserted into a center hole provided in the output gear 61 of the input shaft 14b, and is supported via a needle bearing.

A PTO power switching mechanism 83 as a clutch mechanism for connecting and disconnecting power to and from the mid PTO shaft 25 is provided on the PTO drive main shaft 68. The PTO power switching mechanism 83 is arranged as shown in FIG. , Two output gears rotatably arranged on the PTO drive main shaft 68, ie, the rear PTO
The output gear 84 and the mid-PTO output gear 86, and the PTO drive spindle 68 at a position between the two output gears 84 and 86.
And a clutch slider 85 mounted on the spline hub 88 so as to be relatively non-rotatable and slidable in the axial direction. The clutch slider 85 is linked to a PTO switching lever provided at an appropriate position on the vehicle seat. The two output gears 84
Each of the gears 86 has a tooth portion that can be engaged with the clutch slider 85, and is engaged with one or both of the two output gears 84 and 86 by sliding the clutch slider 85 in the axial direction. I am getting it. Thus, the rotation of the PTO drive main shaft 68 is controlled by the output gear 8.
It will be output to either one or both of 4.86.

As shown in FIG. 3, a rear PTO transmission gear 87 is fixed to the first rear PTO transmission shaft 82, and the rear PTO transmission gear 87 is connected to the PTO power switching mechanism 83.
Of the rear PTO output gear 84. A second rear PTO transmission shaft 92 is disposed concentrically behind the partition wall 108 of the first rear PTO transmission shaft 82, and is integrally connected to the first rear PTO transmission shaft 82 via a coupling 93. As shown in FIG. 4, the second rear PTO transmission shaft 92 extends to the third chamber 133, and is interlocked to the rear PTO shaft 23 by gears 94 and 95.

Next, the mid-PTO drive train 1 from the PTO drive main shaft 68 to the mid-PTO shaft 25
15 will be described. As shown in FIG. 2, the auxiliary transmission mechanism 43 and the differential gear 56 in the first chamber 131 are provided.
A mid-PTO transmission gear 98 is loosely fitted on the traveling output shaft 42 at a position sandwiched between the front and rear and at a position adjacent to the PTO power switching mechanism 83, and the mid-PTO output of the PTO power switching mechanism 83 is The gear 84 is engaged. The mid-PTO output gear 84 is meshed with a first counter gear 99 loosely fitted on the traveling counter shaft 45, and the first counter gear 99 is loosely fitted on the front wheel drive take-out shaft 19. 100 meshed. Then, as shown in FIG. 4, an opening 118 is formed in the bottom of the case half 29b.
The cover 25a is detachably attached to the bottom outer surface so as to cover the opening 118. The cover 2
A mid-PTO shaft 25 is supported on both sides of the front and rear walls of 5a, and the opening 118 is provided to the mid-PTO drive gear 107 fixed on the mid-PTO shaft 25 in the cover 25a.
The transmission gear 100, part of which protrudes into the cover 25a, is meshed. The mid PTO shaft 25
Is unnecessary, the cover 25a provided with the
The second counter gears 99 and 100, the mid-PTO transmission gear 98, the mid-PTO output gear 86, and the PTO power switching mechanism 83 are removed, and the rear PTO output gear 8 is removed.
4 is mounted so that it cannot rotate relative to the PTO drive spindle 68, and a lid is attached to the bottom outer surface of the case half 29b to open the opening 1
What is necessary is just to close 18.

This mid-PTO drive train 115
The relationship between the drive train 112 and the above-described front wheel drive train 112 will be described in detail. That is, as shown in FIG. 2, among the group of gears constituting the mid-PTO drive train 115, the mid-PTO transmission gear 98, the first counter gear 9
9. The three gears of the second counter gear 100 each have a front wheel side drive train 1 according to the corresponding position.
12, the shafts 42, 45, which support the front wheel output gear 58, the intermediate gear 59, and the front wheel transmission gear 60.
19, they are mounted side by side on the same axis. For example, the mid-PTO transmission gear 98 is the front wheel output gear 5
8 is attached to the traveling output shaft 42 side by side.

Therefore, the mid-PTO drive train 1
It can be said that the front wheel drive train 15 and the front wheel side drive train 112 are arranged side by side in the space between the auxiliary transmission mechanism 43 and the differential device 56 described above. Focusing on the direction of power transmission, the mid-PTO drive train 1
15 is transmitted from the mid-PTO transmission gear 98 → the first counter gear 99 → the second counter gear 100, the direction of the power flow is the front wheel drive train 112.
It can also be said that the direction in which the power is transmitted when the upper power is transmitted from the front wheel output gear 58 to the intermediate gear 59 to the front wheel transmission gear 60 is parallel to each other in the space. With this configuration, the two drive trains 115 and 112 can be accommodated in a narrow space without interfering with each other, and can contribute to downsizing of the transmission 14.

Although the embodiments of the present invention have been described above, the technical scope of the present invention is not limited to the above-described embodiments, and the present invention will be apparent from the matters described in the present specification and the drawings. It covers a whole range of technical ideas that are truly intended.

[0044]

The present invention is configured as described above.
The following effects are obtained.

That is, as set forth in claim 1, a transmission mechanism for inputting engine power to change the speed, a front wheel drive output shaft for outputting the power output from the transmission mechanism to the front wheels, and a difference for outputting the power to the left and right rear wheels. In a transmission of a tractor including a moving device and a mid PTO shaft, the mid PTO is inserted into a space between the differential device and the transmission mechanism.
From the clutch mechanism for connecting and disconnecting power to the shaft,
Since the first drive train leading to the O-axis and the second drive train leading from the transmission mechanism to the front wheel drive take-out shaft are juxtaposed, the first and second two drive trains are connected to the differential device or It can be arranged without interfering with the transmission mechanism and the clutch mechanism, and by arranging two drive trains, the space occupied by both drive trains can be made compact. Therefore, it is possible to contribute to downsizing of the transmission.

According to a second aspect of the present invention, a rear PTO shaft is further provided, and power is supplied to the rear side of the clutch mechanism at the rear stage.
Since a PTO power switching mechanism capable of switching between a state where power is transmitted to the TO shaft and a state where power is transmitted to the mid PTO shaft is interposed, the power transmission destination is the rear PTO in addition to the effects shown in claim 1. Alternatively, since the function of switching to the mid-PTO can be performed by the clutch mechanism, a special mechanism for performing the switching is not required, which can also contribute to downsizing of the transmission.

According to a third aspect of the present invention, a clutch mechanism for connecting / disconnecting the engine power to / from the shaft is disposed on one side of a shaft constituting the output side of the clutch mechanism. Since the brake device for applying the braking force to the shaft is arranged on the other side when the clutch mechanism is turned off, in addition to the effect shown in claim 1, the brake device is braked when the clutch mechanism is turned off. Since it is configured to perform the action, when the power to the rear PTO shaft or the mid PTO shaft is cut off, the braking action is immediately generated, and the co-rotation can be effectively prevented. Further, since the second clutch mechanism and the brake device can be conveniently arranged in a compact space on one shaft, it is possible to contribute to downsizing of the transmission. Further, since the distance between the second clutch mechanism and the brake device can be reduced, the configuration for interlocking the second clutch mechanism and the brake device as described above can be simplified.

According to a fourth aspect of the present invention, some of the gears constituting the first and second drive trains are supported on a shaft constituting the speed change mechanism. Since the first and second drive trains can be further downsized, it can contribute to downsizing of the entire transmission.

[Brief description of the drawings]

FIG. 1 is an overall side view of a tractor provided with a transmission of the present invention.

FIG. 2 is a side sectional development view of the transmission.

FIG. 3 is a plan sectional view of a transmission.

FIG. 4 is a sectional view taken along the line XX in FIG. 2;

FIG. 5 is a hydraulic circuit diagram of the tractor.

FIG. 6 is an enlarged sectional view showing a state in which the brake housing is inserted into a recess of a partition wall and assembled.

[Explanation of symbols]

14 Transmission 19 Front Wheel Drive Extraction Shaft 25 Mid PTO Shaft 43 Secondary Transmission Mechanism (Transmission Mechanism) 56 Differential Device 68 PTO Drive Main Shaft (Axis Constituting Input Side of Clutch Mechanism) 69 PTO Clutch Mechanism (Second Clutch Mechanism) 83 PTO power switching mechanism (clutch mechanism for connecting / disconnecting power to / from the mid PTO shaft) 97 Brake device 112 Front wheel side drive train (second drive train) 115 Mid PTO drive train (first drive train)

 ──────────────────────────────────────────────────続 き Continued on front page F-term (reference)

Claims (4)

[Claims] A transmission mechanism for inputting engine power to change the speed, a front wheel drive output shaft for outputting power output from the transmission mechanism to front wheels, and a differential device for outputting power to left and right rear wheels;
A transmission for a tractor including a mid-PTO shaft, wherein a space between the differential device and the transmission mechanism is provided with a first mechanism extending from a clutch mechanism for connecting / disconnecting power to / from the mid-PTO shaft to the mid-PTO shaft. Drive train,
A tractor transmission, wherein a second drive train extending from the speed change mechanism to the front wheel drive take-off shaft is arranged side by side. A rear PTO shaft, and a rear stage of the clutch mechanism for transmitting power to the rear PTO shaft; and a power transmission to the mid PTO shaft.
2. The tractor transmission according to claim 1, wherein a switchable PTO power switching mechanism is interposed. 3. A clutch mechanism for connecting / disconnecting engine power to / from the shaft which constitutes an output side of the clutch mechanism is disposed on one side of the shaft. The transmission of a tractor according to claim 1, wherein a brake device for applying a braking force to the shaft is disposed on the other side. 4. The tractor transmission according to claim 1, wherein a shaft constituting the transmission mechanism supports some of the gears constituting the first and second drive trains.