JP2000185564A - Transmission unit for agricultural vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a compact driving transmission for an agricultural vehicle by linking the center gear through a steering clutch to the driving unit drive gear, and by operating the steering clutch with hydraulic pistons. SOLUTION: A shaft 28 of a center gear 26 is linked so that it rotates as an integrated unit with the center gear 26. A steering clutch 30a is configured by clutch bodies 31, 32. The clutch body 31 is provided in the shaft portion, positioned at the opposite side of the center gear 26 with respect to the driving unit drive gear 12a of the shaft 28. The clutch body 32a is provided at the end part of a transmission gear body 32 which envelops and slides freely with respect to the shaft 28 while engaged with the driving unit drive gear 12a. A hydraulic piston Pa, which is positioned on the opposite side of the center gear 26 with respect to the driving unit drive gear 12a, is slidably operated, thereby a transmission gear body 32 is engaged and disengaged by the steering clutch 30a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive gear for driving a vehicle, which is located on the lateral side of a center gear that can be driven to rotate, and a transmission that meshes with the drive gear for a drive and that is slidably fitted on the support shaft of the center gear. Body, and a steering clutch attached to the transmission so as to perform body steering by turning on and off the rotational power from the center gear to a traveling device, and a hydraulic piston connects the transmission to the traveling device drive gear. A traveling transmission device for an agricultural work vehicle configured to perform a sliding operation while being engaged so that a steering state in which the steering clutch is engaged and a steering state in which the steering clutch is disengaged appear. About.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 13, a clutch claw C2 attached to a boss portion 26a of a center gear 26 and a clutch provided at an end of a transmission 32 on a side gear side, as shown in FIG. In some cases, the steering clutch 30 is configured by the claw C1, and a hydraulic piston Pa is provided in a piston chamber 20c provided in a transmission case portion 20a located on the opposite side of the center gear 26 with respect to the traveling device drive gear 12a. That is, the piston chamber 20
When the hydraulic piston Pa is slid toward the center gear 26 by supplying pressure oil to the transmission gear 3c, the hydraulic piston Pa
The transmission body 32 is slid toward the center gear 26 by pressing the second operation portion 32b. Then, the clutch pawl C1 of the transmission 32 is disengaged from the clutch pawl C2 of the center gear 26 to the inward side of the boss portion 26a, and the steering clutch 30 is disengaged to transmit the rotational power from the center gear 26 to the traveling device drive gear 12a. Expires. From this state, the hydraulic oil is discharged from the piston chamber 20c, and the transmission element 32 and the hydraulic piston Pa are slid toward the piston chamber 20c by the restoring force of the return spring 34 acting on the transmission element 32. Then, the clutch claw C1 of the transmission 32 moves outward from the boss portion 26a from a position disengaged from the clutch claw C2 of the center gear 26, meshes with the clutch claw C2 of the center gear 26, and the steering clutch 30
And the rotational power of the center gear 26 is transmitted to the traveling device drive gear 12a. Then, the hydraulic piston Pa is connected to the traveling device drive gear 12 of the support shaft 28 of the center gear 26.
a, an oil chamber is formed between the support shaft 28 and the center gear 26, and an operation oil passage is provided inside the center gear support shaft 28. Compared to providing a rotary joint between the cases 20 and operating the hydraulic piston Pa, the hydraulic piston can be driven by a hydraulic circuit with a simple structure such that an oil passage in the support shaft and a rotary joint are not required.

[0003]

In the case of the conventional traveling transmission, it is necessary to secure a space for disposing the steering clutch between the center gear and the traveling device drive gear. The distance D from the center gear 26 to the traveling device drive gear 12a shown in FIG. Because of this and the fact that the center gear and the traveling device drive gear are arranged inside the bottom portion of the transmission case in this type of traveling transmission, the length of the bottom portion of the transmission case in the lateral direction of the machine body, so-called, The width was large. As a result, when working in a wet field, when the bottom of the mission case enters the mud portion of the field, the running load is increased due to the resistance applied by the mud to the mission case. SUMMARY OF THE INVENTION An object of the present invention is to provide a traveling power transmission for an agricultural work vehicle in which a hydraulic circuit for a hydraulic piston can be obtained with a simple structure, and a lateral width of a transmission case portion including a center gear and a traveling device driving gear can be reduced as much as possible. It is in.

[0004]

The constitution, operation and effect of the invention according to claim 1 are as follows.

[Structure] A traveling device drive gear located on the lateral side of a drive-rotatable center gear, a transmission that meshes with the travel device drive gear and is slidably fitted to the support shaft of the center gear, Each of the steering clutches is provided on the transmission so as to perform the body steering by turning on and off the rotational power to the traveling device, and the hydraulic piston slides while keeping the transmission engaged with the traveling device drive gear. In the traveling transmission device for an agricultural work vehicle, the driving shaft is configured to display a steering state in which the steering clutch is engaged and a steering state in which the steering clutch is disengaged. And the center gear is rotatably connected to the center gear, and the steering clutch is provided on a support shaft portion of the support shaft, which is located on a side opposite to the center gear with respect to the traveling device drive gear. And is provided between the said transmission member, wherein the said center gear hydraulic piston relative to the traveling device driving gear is disposed on the opposite side.

[Operation] The hydraulic piston is disposed on the opposite side of the center gear with respect to the traveling device drive gear, and an oil chamber for the hydraulic piston is formed in a fixed portion such as a transmission case portion to operate the hydraulic piston. Enable. When the hydraulic piston is operated, the transmission element is slid to operate the steering clutch so that the steering clutch is engaged and disengaged. The engaged steering clutch engages with the support shaft that rotates integrally with the center gear and the transmission gear that meshes with the traveling device drive gear. The steering clutch, which is linked to the body and is disconnected, disconnects the connection between the support shaft and the transmission. This eliminates the need to provide the internal oil passage of the center gear support shaft and the rotary joint as described above in the operation oil passage of the hydraulic piston, and provides a steering clutch between the support shaft portion and the transmission. The steering clutch can be operated by operating the transmission by the hydraulic piston while arranging the device drive gear as close as possible to the center gear. With this clutch operation, the rotational power of the center gear can be transmitted to the traveling device or from the center gear to the traveling device. The steering operation of the aircraft can be performed by turning off the rotation power transmission.

[Effect] Although the steering clutch can be operated by operating the hydraulic piston by a simple hydraulic circuit which does not require the internal oil passage of the support shaft and the rotary joint, the driving device is driven as compared with the prior art. By shifting the gear closer to the center gear, the width of the transmission case part that houses the drive gear and the center gear is narrowed, and even if this transmission case part gets into the mud, it can run advantageously while minimizing the resistance due to this. .

The structure, operation and effect of the invention according to claim 2 are as follows.

In the structure according to the first aspect of the present invention, the body is steered by applying a braking force to the traveling device by pressing a brake disk which is integrally and slidably engaged with the transmission. A steering brake is provided, and the hydraulic piston slides the brake disc, the steering clutch is engaged, and the steering brake is off. It is configured such that a slow turning steering state in which the steering is turned off and a sharp turning steering state in which the steering clutch is released and the steering brake is turned on appear.

[Operation] When the hydraulic piston is operated, the steering clutch is operated by the hydraulic piston and the steering brake is operated. The turning state can be changed to change the running direction with a large turning radius, or the sharp turning steering state can be changed to change the running direction with a small turning radius.

[Effect] In a wet field, a vehicle that travels along the steering direction with as little accuracy as possible due to the low running resistance received by the transmission case, can easily travel straight, large radius, and small radius by simply operating the hydraulic piston. You will be in a state where you can steer as you go.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, a self-propelled body which is self-propelled by a pair of left and right crawler traveling devices 10a and 10b and has a boarding type driving section and a driving section located below a driver's seat 1 is shown. At the front, a cutting pre-processing device 2 is connected by a lift cylinder 3 so as to swing up and down, and a threshing device 4 located behind the pre-cutting device 2, and a threshing device 4 located at a side of the threshing device 4. A grain tank 5 is provided on the self-propelled body to form a combine. That is, the pre-cutting treatment device 2 causes the planted grain culm of rice, wheat or the like to be raised and raised by the device 2a, and also performs the cutting process by the clipper-type cutting device 2b. It is conveyed to the rear side of the machine in the vertical position by the transfer device 2c composed of the stock-side pinching transfer device that acts on the base side and the tip-side locking transfer device that acts on the tip side, and the transfer end portion is set to the side-down position. The posture is changed and the feed is supplied to the start end of the threshing feed chain 4a of the threshing device 4. The threshing device 4 includes a threshing feed chain 4
a, the spike tip side of the harvested grain culm is supplied to the handling chamber, threshing is performed by a handling cylinder that rotates around an axis in a direction along the machine longitudinal direction, and threshing grains are transported to the grain tank 5 and supplied. Go.

An engine 6 is provided in the prime mover, and the rotational output of the engine 6 is transmitted to the traveling devices 10a and 10b by a traveling transmission shown in FIGS. That is, the rotational power of the output shaft 6 a of the engine 6 is transmitted to the input shaft 21 of the transmission case 20 via the belt tension clutch 7. Inside the transmission case 20, a rotating power of the input shaft 21 is transmitted to an input shaft 23 a of a first auxiliary transmission 23 via a gear mechanism 22, and the cylinder is fitted around the input shaft 21 so as to be relatively rotatable. The turning power of the output shaft 23b of the first subtransmission 23 formed of a shaft is transmitted to the second subtransmission 24 having two transmission clutches 24a and 24b, and the rotation of the output shaft 24c of the second subtransmission 24 is transmitted. Power is supplied to four transmission clutches 25a to 25d.
To the main transmission 25 having the
The output gears 25g and 25h, which are rotatably supported by the pair of output shafts 25e and 25f, respectively, mesh with one center gear 26 to transmit rotational power. The crawler drive shaft 11a of the left traveling device 10a of the pair of traveling devices 10a and 10b is rotatably provided integrally with the rotating power of the center gear 26, and the left traveling device located near the side of the center gear 26. The crawler drive shaft 11b of the right traveling device 10b of the pair of traveling devices 10a and 10b transmits the rotational power of the center gear 26 to the driving gear 12a via the left steering clutch 30a so as to be integrally rotatable. And a right steering clutch 30b is attached to the right traveling device drive gear 12b located near the side of the center gear 26.
To communicate through. That is, the rotational power from the main transmission 25 is branched and transmitted to the left traveling device 10a and the right traveling device 10b by the center gear 26.

The first auxiliary transmission 23 is provided with the input shaft 23a.
And a shift gear body 23c which is integrally rotatably and slidably supported for meshing with the spline. The shift gear body 23c is slid by manual operation of a shift lever (not shown) interlocked with the shift gear body 23c, so that the output gear 23d and the shift gear 23e are also used as the shift gear supported by the output shaft 23b so as to be rotatable integrally. , The first subtransmission 23 shifts in two stages, high speed and low speed. That is, when one of a pair of gears provided in the shift gear body 23c meshes with the output gear 23d, the state is set to a low speed state so that the rotational power of the input shaft 23a is transmitted to the output gear 23d via the shift gear body 23c. .
The other gear of the shift gear body 23c is the transmission gear 23e.
, The rotational power of the input shaft 23a is
3c, the transmission gear 23e, and the high-speed state are transmitted to the output gear 23f via the output shaft 23b.

One of the two transmission clutches 24a and 24b of the second auxiliary transmission 24 is a low-speed clutch, and is relatively engaged with the output gear 23f of the first auxiliary transmission 23 and relatively to the output shaft 24c. The rotatable low-speed transmission gear 24d is connected to the output shaft 24c so as to rotate integrally with the output shaft 24c, or the connection is released. The other 24b of the two transmission clutches 24a and 24b is
A high-speed clutch, and a high-speed transmission gear 24e rotatably supported on the output shaft 24c in a state in which it meshes with the output gear 23d of the first auxiliary transmission 23; Or disconnect this connection. As a result, the two transmission clutches 24a, 24b
Is operated such that one is turned on and the other is turned off, whereby the second subtransmission 24 shifts in two stages, high speed and low speed. That is, by turning on the low-speed clutch 24a and turning off the high-speed clutch 24b, the rotational power of the output gear 23f of the first auxiliary transmission 23 is transmitted to the low-speed transmission gear 24.
(d) The vehicle enters the low speed state so as to be transmitted to the output shaft 24c via the low speed clutch 24a. By disengaging the low-speed clutch 24a and turning on the high-speed clutch 24b, the first
The high speed state is established so that the rotational power of the output gear 23d of the subtransmission 23 is transmitted to the output shaft 24c via the high speed transmission gear 24e and the high speed clutch 24b.

The four transmission clutches 25 of the main transmission 25
The clutch 25a among the output gears 24f and 24g is a first speed clutch, and is connected to one output gear 24f of a pair of output gears 24f and 24g supported by the output shaft 24c of the second auxiliary transmission 24 so as to be integrally rotatable. The output shaft 25 is engaged with the output shaft 25.
The transmission gear 25j rotatably supported by e is connected to the output shaft 25e so as to rotate integrally with the output gear 25e, and this connection is released. Four shift clutches 25a to 25d
The clutch 25b is a second-speed clutch, and a transmission gear 25k rotatably supported by the output shaft 25f while meshing with the output gear 24g of the second auxiliary transmission 24 is connected to the output shaft 25f. The connection is made so as to rotate together, or this connection is released. The clutch 25c of the four transmission clutches 25a to 25d is a third speed clutch, and the output gear 24 of the second auxiliary transmission 24 is used.
The transmission gear 25m rotatably supported on the output shaft 25e while meshing with the g is connected to the output shaft 25e so as to rotate integrally with the output shaft 25e, or this connection is released.
Clutch 2 of four shift clutches 25a to 25d
Reference numeral 5d denotes a reverse clutch, which integrally rotates the transmission gear 25n, which is rotatably supported by the output shaft 25f, with the output shaft 25f in a state in which the output shaft 25e is engaged with the transmission gear 25j, which is rotatably supported. And disconnect the connection. The output gear 25g supported by the output shaft 25e so as to rotate integrally with the output gear 25g supported by the output shaft 25f so as to rotate integrally.
5h also meshes with the center gear 26. By operating the four speed change clutches 25a to 25d so that one of them is engaged and the other three are disengaged, the main transmission 25 shifts to a total of four stages of three forward speeds and one reverse speed. . That is, by turning on the first speed clutch 25a and disengaging the other clutches 25b to 25d, the turning power of the output gear 24f of the second auxiliary transmission 24 is transmitted to the transmission gear 25j, the first speed clutch 25a, and the output shaft. 25e,
The first forward speed is set so as to be transmitted to the center gear 26 via the output gear 25g. By turning on the second speed clutch 25b and turning off the other clutches 25a, 25c, 25d, the rotational power of the output gear 24c of the second auxiliary transmission 24 is transmitted to the transmission gear 25k, the second speed clutch 25b, and the output shaft. 2
5f, the second forward speed is established so as to be transmitted to the center gear 26 via the output gear 25h. By engaging the third speed clutch 25c and disengaging the other clutches 25a, 25b, 25d, the output gear 24c of the second subtransmission 24 is operated.
Is transmitted to the center gear 26 via the transmission gear 25m, the third speed clutch 25c, the output shaft 25e, and the output gear 25g. Reverse clutch 25d
, And the other clutches 25a to 25c are turned off to transmit the rotational power of the output gear 24f of the second auxiliary transmission 24 to the transmission gear 25j, the transmission gear 25n, the reverse clutch 25d, the output shaft 25f, and the output gear 25h. To the center gear 26 through the reverse gear.

Each of the two transmission clutches 24a, 24b of the second auxiliary transmission 24 and the four transmission clutches 25a to 25d of the main transmission 25 is connected to a hydraulic piston PL, PH, P1 located inside a clutch body. ~ P
3, the hydraulic clutch is configured to perform the on / off operation by PR. The six hydraulic pistons PL, PH,
One shift valve 41 for operating P1 to P3 and PR, and one shift lever 42 provided in the driving section so as to swing freely in the longitudinal direction of the machine in conjunction with the shift valve 41
The speed change operation device 40 having the above configuration is configured as shown in FIG.

That is, the transmission valve 41 has a neutral position N, six forward positions F1 to F6, two reverse positions RL,
It is configured as a rotary valve with RH. An input side of the shift valve 41 is connected to a pressure reducing valve 43 for setting a clutch pressure.
Is connected to a hydraulic pump 45 so as to be supplied with pressure oil through an oil supply passage 44 having an accumulator 4.
6 is connected to a delay circuit 47 having
Are connected to the six shift clutches 24a, 24b,
25a to 25d each of the hydraulic pistons PL, P
H, P1 to P3, operating oil passage 4 in piston chamber provided with PR
The operation oil is supplied and discharged via 8 to 53. In addition, the lubricating oil passage 54 shown in FIG. 5 is configured to transfer the oil discharged from the hydraulic circuit that operates the lift cylinder 3 to the second auxiliary transmission 24 and the transmission clutches 24 a of the main transmission 25.
24b, 25a to 25d are supplied for lubrication.

That is, when the shift valve 42 is operated to swing to the neutral position N by swinging the shift lever 42 in the longitudinal direction of the machine, the shift valve 41 is moved to the two shift clutches 24a and 24b of the second auxiliary transmission 24, respectively. Hydraulic piston P
L and PH are also the four transmission clutches 25 of the main transmission 25.
The hydraulic pistons P1 to P3, PR of the respective a to 25d are also operated to the clutch disengagement positions. As a result, both the second auxiliary transmission device 24 and the main transmission device 25 enter a neutral state so as to stop the transmission, and the traveling of the aircraft stops. When the shift lever 42 is further pivotally operated forward to move the shift valve 41 to the forward position F1, the shift valve 41 shifts the hydraulic piston PL of the low-speed clutch 24a of the second auxiliary transmission 24 to the high-speed clutch at the engaged position. The hydraulic piston PH of the first transmission clutch 25a of the main transmission 25 is engaged with the hydraulic piston PH of the other transmission clutches 25b to 25d and the hydraulic pistons P2 to P3 of the other transmission clutches 25b to 25d are clutched. Operate to the cutting position. As a result, the second sub-transmission 24 is at a low speed, the main transmission 25 is at the first forward speed, and the vehicle travels at the first forward speed. When the shift lever 42 is further operated to the front side of the fuselage to operate the shift valve 41 to the forward position F2, the shift valve 4
1 operates the hydraulic piston PL of the low speed clutch 24a of the second auxiliary transmission 24 to the clutch engaged position and the hydraulic piston PH of the high speed clutch 24b to the clutch disengaged position, and the hydraulic piston P2 of the second speed clutch 25b of the main transmission 25. With the other shift clutches 25a, 25
The hydraulic pistons P1, P3, PR of c, 25d are respectively operated to the clutch disengagement position. As a result, the second subtransmission 24 is at a low speed and the main transmission 25 is at the second forward speed,
The aircraft runs at the second forward speed. When the shift lever 42 is further swung forward to move the shift valve 41 to the forward position F3, the shift valve 41 shifts the hydraulic piston PL of the low-speed clutch 24a of the second auxiliary transmission 24 to the high-speed clutch 24b at the clutch engaged position. Is operated to the clutch disengagement position, and the third speed clutch 25 of the main transmission 25 is operated.
The hydraulic pistons P1, P2, and PR of the other shift clutches 25a, 25b, and 25d are operated to the clutch disengaged positions, respectively, with the hydraulic piston P3 of c being in the clutch engaged position.
As a result, the second sub-transmission 24 is driven at low speed and the main transmission 2
5 is the third forward speed, and the aircraft runs at the third forward speed. When the shift lever 42 is further swung to the front side of the fuselage to operate the shift valve 41 to the forward position F4, the shift valve 41
Operates the hydraulic piston PL of the low-speed clutch 24a of the second auxiliary transmission 24 at the clutch disengaged position and the hydraulic piston PH of the high-speed clutch 24b to the clutch engaged position, and changes the hydraulic piston P1 of the first speed clutch 25a of the main transmission 25. Other shift clutches 25b to 25d at the clutch engaged position
Each hydraulic piston P2, P3, PR is operated to the clutch disengagement position. As a result, the second sub-transmission 24 is at a high speed, the main transmission 25 is at the first forward speed, and the vehicle travels at the fourth forward speed. When the shift lever 42 is further swung to the front side of the fuselage to operate the shift valve 41 to the forward position F5, the shift valve 41 shifts the hydraulic piston PL of the low speed clutch 24a of the second auxiliary transmission 24 to the high speed clutch at the clutch disengaged position. The hydraulic piston PH of the second speed clutch 25b of the main transmission 25 is moved to the clutch engaged position, and the hydraulic pistons P of the other shift clutches 25a, 25c, 25d are moved to the clutch engaged position.
1, P3, PR are operated to the clutch disengagement position. As a result, the second auxiliary transmission 24 is at a high speed, the main transmission 25 is at the second forward speed, and the vehicle travels at the fifth forward speed. The shift lever 42 is further swung forward to the front of the fuselage to shift the shift valve 4.
1 is moved to the forward position F6, the transmission valve 41
Hydraulic piston P of low-speed clutch 24a of auxiliary transmission 24
L is set to the clutch disengaged position, and the hydraulic piston PH of the high speed clutch 24b is operated to the engaged position.
When the hydraulic piston P3 of the third speed clutch 25c is engaged, the other speed change clutches 25a, 25b, 25
d Operate the respective hydraulic pistons P1, P2, PR to the clutch disengagement position. Thereby, the second auxiliary transmission 24
At a high speed, the main transmission 25 becomes the third forward speed, and the aircraft travels at the sixth forward speed. When the shift lever 42 is swung from the neutral position to the rear side of the machine to operate the shift valve 41 to the reverse position RL, the shift valve 41 moves the hydraulic piston PL of the low-speed clutch 24a of the second auxiliary transmission 24 to the clutch engaged position. By operating the hydraulic piston PH of the high speed clutch 24b to the clutch disengaged position, the reverse clutch 25 of the main transmission 25 is operated.
The hydraulic piston PR of each of the other shift clutches 25a to 25c is set at the clutch engagement position.
To P3 to the clutch disengagement position. As a result, the second auxiliary transmission 24 is at a low speed and the main transmission 25 is in a reverse state, and the vehicle travels at the first reverse speed. When the shift lever 42 is further swung to the rear side of the fuselage to operate the shift valve 41 to the reverse position RH, the shift valve 41 shifts the hydraulic piston PL of the low speed clutch 24a of the second auxiliary transmission 24 to the high speed clutch at the clutch disengaged position. The hydraulic piston PH of the main transmission 25 is operated to the clutch engaged position, the hydraulic piston PR of the reverse clutch 25d of the main transmission 25 is operated to the clutch engaged position, and the hydraulic pistons P1 to P3 of the other shift clutches 25a to 25c are operated to the clutch disengaged position. I do. As a result, the second auxiliary transmission 24 is at a high speed and the main transmission 25 is in a reverse state, and the vehicle travels at the second reverse speed. Even when the shift lever 42 is operated to the forward or reverse operation position for traveling, the hydraulic piston PL of the shift clutches 25a, 25b in the second auxiliary transmission 24 is operated by the pressure accumulation by the accumulator 46 of the delay circuit 47. , PH after the hydraulic pressure acting on the transmission reaches a predetermined transmission pressure.
5, the hydraulic pressure acting on the hydraulic pistons P1 to P3 and PR of the transmission clutches 25a to 25d rises to a predetermined transmission pressure. As a result, the transmission clutches 25a to 25d of the main transmission 25 reach the transmission clutch pressure after the transmission clutches 24a and 24b of the second auxiliary transmission 24 reach the transmission clutch pressure.

As shown in FIG. 4, a left steering brake 60a is provided between the left traveling device drive gear 12a and the left steering clutch 30a so as to act on the left traveling device 10a. A right steering brake 60b is provided between the right traveling device drive gear 12b and the right steering clutch 30a so as to act on the right traveling device 10b.

Left steering clutch 30a and right steering clutch 3
Each of the reference numerals 0b penetrates the boss of the center gear 26 to support the center gear 26, and is supported at both ends by a portion 20a of the transmission case 20 via a ball bearing 27 so as to be relatively rotatable. Of the traveling device drive gear 12 of the rotary support shaft 28
a, a drive-side clutch body 31 externally fitted to a spindle portion located on the opposite side of the center gear 26 with respect to the center gear 26, and a cylindrical transmission externally fitted to the rotary support shaft 27 so as to be relatively rotatable and slidable. And a passive clutch body 32a comprising a clutch claw provided at an end of the body 32. Support shaft 28
Is engaged with the spline portion on the inner peripheral surface side of the boss portion of the center gear 26 at the intermediate portion, so that the center gear 26
, And are connected so as to rotate integrally therewith. The clutch body 31 rotates integrally with the rotation support shaft 28 by engaging with the spline portion on the outer peripheral surface side of the rotation support shaft 28. The transmission 32 meshes with the gear portion G provided on the outer peripheral surface side thereof so as to transmit rotational power to the traveling device drive gears 12a and 12b, and the support shaft 28 is maintained while maintaining the meshing. And the driven side clutch body 32a is engaged with the clutch claw 31a of the drive side clutch body 31 and the driven side clutch body 32a is disengaged from the clutch claw 31a of the drive side latch body 31. It is configured to switch to the off state. As a result, the left steering clutch 30a is
b, the transmission body 32 is slid and the clutch body 32a on the passive side is shifted to the clutch pawl 31a of the clutch body 31 on the drive side.
When the clutch body 32a is engaged with the clutch body 31a, the clutch body 32a on the passive side is disengaged from the clutch claw 31a of the clutch body 31 on the drive side, so that the clutch body 32a is in the off state. Then, in the engaged state, the rotation shaft 28 that rotates integrally with the center gear 26 and the transmission 32 that meshes with the traveling device drive gears 12a and 12b are connected so as to rotate integrally with each other. Is transmitted to the traveling device drive gears 12a and 12b. In the disengaged state, the transmission from the center gear 26 to the traveling device drive gears 12a and 12b is cut off by releasing the connection between the rotation support shaft 28 and the transmission 32 so that the two rotate relative to each other.

The left steering brake 60a and the right steering brake 6
Each of 0b includes a plurality of brake disks 61 that rotate integrally with the transmission body 32 when the inner circumference engages with the gear portion G of the transmission body 32, and the inner circumference enters between the brake disks 61. In this state, a multi-plate type friction brake body composed of a plurality of friction discs 62 that are non-rotatably supported by the transmission case 20 by engaging the outer peripheral side with the locking portions 20b of the transmission case 20. A brake operation plate 63 as a brake operation member slidably supported by the locking portion 20b on the side opposite to the traveling device drive gears 12a and 12b.
Is configured to be switched between an on state and an off state by operating. That is, the brake operation plate 63 is pressed toward the traveling device drive gears 12a and 12b, and the brake disc 61 and the friction disc 6 are moved.
2 is a receiving portion 64 which is a part of the transmission case 20.
, The brake body is moved to the traveling device drive gear 12.
By applying a friction braking force to the transmission 32 meshing with the transmission members a and 12b, the traveling devices 10a and 10b are brought into a state of entering into a braking operation. Then, when the pressing of the brake disc 61 and the friction disc 62 against the receiving portion 64 by the brake operation plate 63 is released, the brake body releases the application of the frictional braking force to the transmission 32, thereby braking the traveling devices 10a and 10b. The cutting state is set to cancel the action.

One left hydraulic piston P for operating both the left steering clutch 30a and the left steering brake 60a.
a, the right steering clutch 30b and the right steering brake 60b
And one steering valve 7 for operating two hydraulic pistons Pa and Pb.
1, one variable relief valve 72 for adjusting the hydraulic pressure acting on the two hydraulic pistons Pa and Pb, and the variable relief valve 72 and the steering valve 71 interlocked with each other via an interlocking mechanism 79 so that the operating unit can move the machine sideways. The steering operation device 70 including one steering lever 73 provided so as to be freely swingable in the direction is configured as follows.

That is, as shown in FIG. 4, the left hydraulic piston Pa is disposed on the side opposite to the center gear 26 with respect to the left traveling device drive gear 12a, and the transmission case portion 2
0a, the right hydraulic piston Pb is disposed on the opposite side of the center gear 26 with respect to the right traveling device drive gear 12b, and attached to the inner surface of the transmission case portion 20a. Hydraulic piston P
b also includes the steering clutches 30a and 30b and the steering brake 60.
a and 60b are operated as follows. That is, when operation oil is supplied to a piston chamber 20c formed in the transmission case portion 20a so as to slidably support the hydraulic pistons Pa and Pb, the hydraulic oil projects the hydraulic pistons Pa and Pb from the piston chamber 20c. Sliding operation to the side to be performed. Then, the hydraulic pistons Pa, Pb become the hydraulic pistons Pa, Pb.
By pressing the operating portion 32b of the transmission 32 formed of a plate for smoothing the relative rotation between the Pb and the transmission 32, first, only the transmission 32 is slid toward the center gear 26, and the passive clutch 32a is disengaged. The drive side clutch body 31 is disengaged from the clutch pawl 31a. Thereafter, the operation unit 32
b is in contact with the brake operation plate 63,
The hydraulic pistons Pa and Pb push the brake operation plate 63 toward the center gear 26 via the operation portion 32b of the transmission 32, and the brake operation plate 63 presses the brake disk 61 and the friction disk 62 against the receiving portion 64. Press until From this state, the piston chamber 20
When c is operated to drain the oil, the return springs 34 provided inside the transmission 32 so as to slidably urge the transmission 32 toward the drive-side clutch body 31 cause the hydraulic pistons Pa and Pb to return.
Is slid to the side to be retired to the piston chamber 20c. Then, the hydraulic pistons Pa and Pb move to the brake operation plate 6.
3 is released and the brake operation plate 6 is released.
3 is released from the pressing of the brake disk 61 and the friction disk 62 against the receiving portion 64. Thereafter, the hydraulic pistons Pa and Pb further slide toward the retreating side into the piston chamber 20c, and the transmission body 32 is slid toward the driving side clutch body 31 by the return spring 34 so that the passive side clutch body 32a is driven. Clutch claws 31a of the clutch body 31
To be engaged. Thus, the steering clutches 30a, 30b are provided by one hydraulic piston Pa, Pb on both the left traveling device 10a side and the right traveling device 10b side.
b and the steering brakes 60a and 60b can be operated, and the steering clutches 30a and 30b are engaged and the steering brakes 60a and 60b are off. An operation can be performed so that a gentle turning state in which the turning of the steering clutch 30a, 30b is turned on and the steering brakes 60a, 60b are in the turned-on state can be alternatively displayed.

As shown in FIG. 5, the steering valve 71 is moved to a neutral position N where the left and right hydraulic pistons Pa and Pb are drained by sliding a spool (not shown), and a left hydraulic piston Pa. The transmission case 20 has a three-position switching valve that switches between three operation positions: a left steering position L for supplying pressure oil and a right steering position R for supplying pressure oil to the right hydraulic piston Pb. It is attached to the outer side of the rear side wall. The input side of the steering valve 71 is connected to the hydraulic pump 45 so as to be supplied with pressurized oil through an oil supply passage 75 provided with a pressure control valve 74 for setting a piston operation pressure. Is connected to the piston chamber 20c having the left hydraulic piston Pa so as to supply and discharge the operating oil via the operating oil passage 76, and the piston chamber 20 having the right hydraulic piston Pb is connected to the piston chamber 20c.
c is connected to supply and discharge operation oil via an operation oil passage 77.

The variable relief valve 72 is mounted on the outer surface of the rear side wall of the transmission case 20 side by side with the steering valve 71 in the lateral direction of the fuselage, and supplies operating oil from both the pair of left and right piston chambers 20c. The flow resistance of the oil in the oil discharge passage 78 discharged to the tank is changed to act on the oil discharge passage 78 so as to adjust the operation stroke of the hydraulic pistons Pa and Pb. That is, when the variable relief valve 72 is operated to a low relief pressure state set for gentle turning, the steering valve 71 is operated to the left steering position L to drive the hydraulic piston Pa, or to the right steering position. Even if the hydraulic piston Pb is driven by operating to R,
The flow resistance of the oil drain passage 78 becomes small, and the hydraulic piston Pa,
The working stroke of Pb becomes small, and the hydraulic pistons Pa,
Pb is applied to the steering clutches 30a and 30b and the steering brake 6
It is possible to maintain a state in which both of 0a and 60b are turned off. When the variable relief valve 72 is operated to a high relief pressure state set for rapid turning, the steering valve 7 is operated.
1 is operated to the left steering position L to drive the hydraulic piston Pa.
Is driven, the flow resistance of the oil drain passage 78 increases, and the operating stroke of the hydraulic pistons Pa and Pb increases, and the hydraulic pistons Pa and Pb move the steering clutches 30a and 3b.
It is possible to drive the steering brakes 60a and 60b so that the steering brakes 60a and 60b are turned on by turning off the switch 0b.

The interlocking mechanism 79 includes a variable relief valve 72
The operation of the relief valve interlocking mechanism 79a for interlocking the operation section of the steering valve 73 with the operation section of the relief valve 72 of the relief valve interlocking mechanism 79a. Terminal interlocking unit 79 for transmitting to
b, when the steering lever 73 switches to the straight traveling position S, the steering valve 71 switches to the neutral position N, and when the steering lever 73 switches to the first left turning position L1, the variable relief valve 72 When switching to the low-pressure side relief pressure state for gentle turning, the steering valve 71 switches to the left steering position L, and the steering lever 73 switches to the first right turning position R1, the variable relief valve 72 switches. It switches to the low pressure side relief pressure state for gentle turning, and the steering valve 71
Is switched to the right steering position R. The terminal interlocking portion 79b is provided with an elastic interlocking portion (not shown) made of an elastically deformable interlocking member, and the steering lever 73 is switched from the first left turning position L1 to the second left turning position L2. In this case, since the steering valve 71 has been switched to the left steering position L first and the operation portion has reached the stroke end, the elastic interlocking portion is elastically deformed, and the steering valve 7
While maintaining 1 at the left steering position L, the variable relief valve 72 switches to the high-pressure side relief pressure state for rapid turning.
When the steering lever 73 is switched from the first right turning position R1 to the second right turning position R2, the steering valve 71 has been switched to the right steering position R first, and the operating portion thereof is operated. Has reached the stroke end, the elastic interlocking portion is elastically deformed, and the variable relief valve 72 switches to the high-pressure-side lily pressure state for rapid turning while maintaining the steering valve 71 at the right steering position L. It is configured as follows.

That is, the steering operation of the fuselage is performed by swinging the steering lever 73. That is, the steering lever 7
3 is operated to the straight traveling position S, the steering valve 71 is set to the neutral position N, and the left hydraulic piston Pa is also shifted to the right hydraulic piston Pb.
Is also operated with the clutch in the bouquet-off operating position. As a result, both the left traveling device 10a and the right traveling device 10b receive the steering clutches 30a, 30b, and the steering brakes 60a,
60b is in a straight-ahead steering state, and the aircraft goes straight. When the steering lever 73 is swung from the straight-ahead position S to the left side of the fuselage to the first left turning position L1, the steering valve 7 is moved.
1 moves to the left steering position L to supply oil to the left hydraulic piston Pa, and operates the right hydraulic piston Pb to the drain side, so that the variable relief valve 72 enters a relief pressure state for gentle turning, and the left hydraulic piston Pa The working stroke is adjusted to the small stroke. As a result, the left traveling device 10a is in a gentle turning steering state in which both the left steering clutch 30a and the left steering brake 60a are off, and the right traveling device 10b is in the right steering clutch 30b.
, The right steering brake 60b is turned to the straight forward steering state, and the aircraft changes its direction to the left with a large turning radius and travels. When the steering lever 73 is further pivoted from the first left turning position L1 to the left side of the fuselage to the second left turning position L2, the steering valve 71 is set to the left steering position L, and the left hydraulic piston Pa is refueled. At the same time, the right hydraulic piston Pb is operated to the oil drain side, and the variable relief valve 72 enters a relief pressure state for rapid turning, thereby adjusting the operating stroke of the left hydraulic piston Pa to the large stroke. As a result, the left traveling device 10a enters a sharp turning steering state in which the left steering clutch 30a is disengaged and the left steering brake 60a is engaged.
b indicates that the right steering clutch 30b is engaged and the right steering brake 60
The vehicle moves in a straight-ahead steering state with b turned, and the aircraft changes its direction to the left with a small turning radius and travels. The steering lever 73 is pivoted from the straight traveling position S to the right side of the aircraft to move to the first right turning position R.
When the steering valve 71 is operated to 1, the steering valve 71 is set to the right steering position R to supply oil to the right hydraulic piston Pb and to operate the left hydraulic piston Pa to the drain side, so that the variable relief valve 72 is in a relief pressure state for gentle turning. Then, the operating stroke of the right hydraulic piston Pb is adjusted to the small stroke. As a result, the left traveling device 10a enters a straight steering state in which the left steering clutch 30a is engaged and the left steering brake 60a is disengaged, and the right traveling device 10b disengages both the right steering clutch 30b and the right steering brake 60b. The vehicle enters the turning steering state, and the aircraft changes its direction to the right with a large turning radius and travels. Steering lever 7
3 is further pivoted from the first right turning position R1 to the right side of the fuselage to be operated to the second right turning position R2.
Moves to the right steering position R to supply oil to the right hydraulic piston Pb and to operate the left hydraulic piston Pa to the drain side, so that the variable relief valve 72 enters a relief pressure state for rapid turning, and the right hydraulic piston Pa operates. Adjust the stroke to the large stroke. As a result, the left traveling device 10a is in a straight-ahead steering state in which the left steering clutch 30a is engaged and the left steering brake 60a is off, and the right traveling device 10b is in the right steering clutch 30a.
The vehicle turns into a sharp turning state in which the right steering brake 60b is turned on when b is turned off, and the aircraft changes its direction to the right with a small turning radius and travels.

As shown in FIGS. 4 and 6, the brake operation plate 63 of the right steering brake 60b is slid in the sliding direction of the transmission 32 separately from the transmission 32 with respect to the transmission case 20. And is supported by the transmission case 20 so as to rotate about the axis of the support shaft 28. An interlocking mechanism is provided between a brake operation shaft 81 rotatably supported by the transmission case portion 20a and an operation lever 82 having an end portion of the brake operation shaft 81 protruding outside the transmission case rotatably provided integrally. The hydraulic piston Pb is controlled by an operation unit including a brake pedal 84 and a brake cylinder 85 interlocked by 83 and a cam mechanism 86 provided between the brake operation plate 63 and the transmission case portion 20a. The brake operating means 80 for operating the right steering brake 60b by operating the brake operating plate 63 without operating the brake operating plate 63 is configured. That is, the brake pedal 8
4 or the brake cylinder 85
By performing the oil draining operation, the brake cylinder 85 is
Is operated to the shortened side, the operating lever 82 is operated to swing from the off position to the on position by the operating force of the brake pedal 84 or the brake cylinder 85 transmitted by the interlocking mechanism 83, and the brake operating shaft 81 is operated by the operating lever. The turning operation is performed in the same turning direction as the swing direction of 82. Then, a half-moon-shaped operation cam portion 8 provided integrally rotatably at an end of the brake operation shaft 81 inside the transmission case.
1a presses against a cam follower formed by an inner wall surface of a groove 63a formed so that the tip end side of the operation cam portion 81a enters into a side surface of the brake operation plate 63, and moves the brake operation plate 63 against the transmission case 20. The rotation operation is performed in the rotation direction A. Then, as shown in FIGS. 7 and 8, the cam mechanism 86 includes a plurality of protrusions 63 b distributed on the side surface of the brake operation plate 63 in the circumferential direction of the plate and a brake on the end surface of the transmission case portion 20 a. A plurality of plate pushing cams 20d dispersed and projected in the circumferential direction of the operating plate 63, and each of the plurality of projecting portions 63b of the brake operating plate 63 is connected to the plate pushing cam 20d of the transmission case portion 20a. When the vehicle rides, the brake operation plate 63 is pushed out toward the center gear 26 by the pushing action due to the inclination of the cam surface of the plate pushing cam 20d. For this reason, the brake operation plate 63 presses the brake disc 61 and the friction disc 62 against the receiving portion 64 while the transmission 33 is positioned on the entry side of the steering clutch 30b, and engages the right steering brake 60b. It is configured to operate. In this state, the brake pedal 84 is operated to the cut position by the restoring force of the return spring, and when the brake oil is supplied to the brake cylinder 85 and the brake cylinder 85 is operated to the extension side, the operation lever 82 returns to the cut position OFF and The projection 63b of the brake operation plate 63 rotates to the side descending from the inclined cam surface of the plate pushing cam 20d of the transmission case portion 20a due to the pressing reaction force of the receiving portion 64, and the brake disk 61 Further, the pressing operation of the friction disk 62 on the receiving portion 64 is released, and the right steering brake 60b is configured to return to the off state. That is, when the vehicle is parked, the right steering brake 60b is switched to the on state, and both the left steering clutch 30a and the right steering clutch 30b are operated to the on state. Acts on both the left traveling device 10a and the right traveling device 10b, and the right steering brake 6
0b can be used for parking while parking. Also,
When the vehicle is traveling straight, depressing the brake pedal 84 causes the operation cable connected to the brake cylinder 85 to bend even when the brake cylinder 85 is in the extended state. The right steering brake 60b is operated to enter and the left and right traveling devices 10a and 10b can be braked.

[Other Embodiments] FIGS. 9 to 11 show a steering operation device 70 having another embodiment. A steering valve 71 of the steering operation device 70 rotates an operation portion 71a. Causes the spool to rotate to the neutral position N
And left steering position L for supplying pressure oil to left hydraulic piston Pa
And a right steering position R for supplying pressure oil to the right hydraulic piston Pb.

A rotary operating shaft 9 rotatably supported by a boss 90a of a valve case 90 in a state where one end of the steering valve 71 is integrally rotatably connected to the operating portion 71a.
1. An operation arm 92 having a base end integrally rotatably connected to an end of the rotation operation shaft 91 protruding outside the valve case to rotate the rotation operation shaft 91, and a steering lever for operating the operation arm 92. The steering valve 71 and the variable valve are controlled by an operation cable 93 connected to the valve 73 and an operation cam 94 for operating a relief valve integrally rotatably connected to a portion of the rotary operation shaft 91 located inside the valve case 90. An interlocking mechanism 70 for interlocking the relief valve 72 with the steering lever 73 is formed, and a return spring 95 supported by the valve case 90 with an intermediate ring portion externally fitted to the boss 90a of the valve case 90. The steering valve 71 is biased to the neutral position N and the operation cam 94 is biased to the neutral position. It is to enable the switching operation of the variable relief valve 72.

That is, as shown in FIG. 11, slidable spring receiving members are provided at both ends of the operation cam 94 for receiving and supporting the relief pressure setting spring 72a of the variable relief valve 72 on the side opposite to the poppet side. An operation cam portion 94a acting on the simple operation portion 72b is provided. As clearly shown in FIG. 12A, one linear end 95a of the return spring 95 and the other linear end 95b are
2, a bent end portion 92a at the base end and a valve case 90.
And a stopper portion 90b composed of the projections.

When the steering lever 73 is swung from the straight-ahead position S to the left side of the fuselage to the first left turning position L1, the inner cable of the operation cable 93 is pulled and the operation arm 92 is moved to the position shown in FIG. (B) from the neutral position n shown in FIG. 12 to the first operation position a shown in FIG.
By rotating the first operation unit 71a, the steering valve 71 is switched from the neutral position N to the left steering position L. At this time, the rotation operation shaft 91 rotates the operation cam 94. Then, the pair of operation cam portions 94a, 94a of the operation cam 94 are formed.
One of the operation cam portions 94a is a variable relief valve 72.
Of the pair of end surfaces 72c, 72c of the operation portion 72b, the operation portion 72b is pushed in by pressing the one end surface 72c, and the variable relief valve 72 is switched to a relief pressure state for gentle turning.

When the steering lever 73 is further pivoted from the first left turning position L1 to the left side of the fuselage to the second left turning position L2, the inner cable of the operation cable 93 is further pulled to operate the operation arm 92. The swing operation is performed to the second operation position b shown in FIG. 12C, and the rotation operation shaft 91 rotates together with the operation arm 92 to rotate the operation unit 7 of the steering valve 71.
1a is further rotated. Even if the operation arm 92 swings from the first operation position a to the second operation position b to increase the stroke in which the spool of the steering valve 71 is rotated, the shape of the oil passage provided in the spool may increase the operation arm 92. , Steering valve 7
1 maintains the same pressure oil supply state as the state in which pressure oil is supplied to the left hydraulic piston Pa when the steering lever 73 is operated to the first left turning position L1. That is, the steering lever 73 is
The steering valve 71 maintains the left steering position L even when operated to the left turning position L2. At this time, the rotation operation shaft 91 further rotates the operation cam 94. Then, this operation cam 9
4. The one operation cam portion 94a of FIG.
The operation part 72b is further pushed in by pressing the one end face 72c of the above, and the variable relief valve 72 is switched to the relief pressure state for rapid turning.

When the steering lever 73 is pivoted from the straight traveling position S to the right side of the fuselage to the first right turning position R1, the inner cable of the operation cable 93 is pushed and the operation arm 92 is moved as shown in FIG. 12) from the neutral position n shown in FIG.
(D), the swing operation is performed to the third operation position c, the rotation operation shaft 91 rotates together with the operation arm 92 to rotate the operation portion 71a of the steering valve 71, and the steering valve 71 is moved from the neutral position N. The position is switched to the right steering position R. At this time, the rotation operation shaft 91 rotates the operation cam 94. Then, the other operation cam portion 94a of the pair of operation cam portions 94a, 94a of the operation cam 94 is connected to the other end surface 72c of the pair of end surfaces 72c, 72c of the operation portion 72b of the variable relief valve 72. The variable relief valve 72 switches to a relief pressure state for gentle turning.

When the steering lever 73 is further pivoted from the second right turning position R1 to the right side of the fuselage to the second right turning position R2, the inner cable of the operation cable 93 is further pushed to operate the operation arm. 12 (e), the rotation operation shaft 91 rotates together with the operation arm 92, and the operation portion 71a of the steering valve 71 is rotated.
Is further rotated. Even if the operation arm 92 swings from the third operation position c to the fourth operation position d to increase the stroke of the rotation of the spool of the steering valve 71, the shape of the oil path provided in the spool may increase. The steering valve 71 maintains the same pressure oil supply state as the state in which pressure oil is supplied to the right hydraulic piston Pb when the steering lever 73 is operated to the second right turning position R1. That is, even if the steering lever 73 is operated to the second right turning position R2, the steering valve 71 maintains the right steering position R. At this time, the rotation operation shaft 91 is
4 is further rotated. Then, the other operation cam portion 94a of the operation cam 94 presses the other end surface 72c of the variable relief valve 72 to further push the operation portion 72b, and the variable relief valve 72 is set to the relief pressure for sudden turning. Switch to state.

When the steering lever 73 is operated to the first left turning position L1 and the second left turning position L2, FIG.
As shown in FIG. 12B, the stopper portion 90b of the valve case 90 acts as a stopper on one end 95a of the return spring 95, and the bent end 92a of the operation arm 92.
Presses against and moves the other end 95b of the return spring 95, the return spring 95 is elastically deformed, and urges the operation arm 92 to swing to the neutral position n. When the steering lever 73 is in the first right turning position R1 and the second right turning position R2
12 (d), the stopper 90b of the valve case 90 acts as a stopper on the other end 95b of the return spring 95, as shown in FIGS. 92a is a return spring 95
The return spring 95 is elastically deformed to move the operating arm 92 by pressing against the other end 95a of the operating arm 92.
To the neutral position n. As a result, the steering lever 73 is moved to the first left turning position L1, the second left turning position L2,
Regardless of which of the right turning position R1 and the second right turning position R2 is operated, the return spring 95 urges the operation cam 94 and the steering valve 71 to the neutral position, and moves the steering lever 73 to the straight traveling position S. , The variable relief valve 72 is reliably returned to the open position, and the steering valve 71 is reliably returned to the neutral position N and positioned.

Instead of the crawler traveling devices 10a and 10b,
The present invention is also applicable to a case in which a wheel-type traveling device in which a plurality of wheels are arranged in the longitudinal direction of the fuselage is employed. Therefore, these crawler traveling devices and wheel type traveling devices are collectively referred to as traveling devices.

The present invention can be applied to various working vehicles such as agricultural tractors in addition to combine harvesters. Therefore, these vehicles are collectively referred to as agricultural work vehicles.

[Brief description of the drawings]

FIG. 1 is a side view of the entire combine.

FIG. 2 is a schematic view of a traveling transmission device.

FIG. 3 is an explanatory view of an arrangement of a transmission shaft and a transmission gear of the traveling transmission device.

FIG. 4 is a sectional view of an arrangement portion of a steering clutch and a steering brake.

FIG. 5 is a schematic diagram of a shift operation device and a steering operation device.

FIG. 6 is a schematic diagram of a brake operation structure.

FIG. 7 is a side view of the cam mechanism.

FIG. 8 is a perspective view of a cam mechanism.

FIG. 9 is an explanatory diagram of a steering operation device including another embodiment.

FIG. 10 is a cross-sectional view of an operation unit of a steering valve in a steering operation device according to another embodiment.

FIG. 11 is a perspective view of an operation portion of a steering valve in a steering operation device according to another embodiment.

FIG. 12 is a diagram illustrating the operation of a return spring according to another embodiment.

FIG. 13 is a sectional view of a conventional traveling transmission.

[Explanation of symbols]

 10a, 10b Traveling device 12a, 12b Traveling device drive gear 26 Center gear 28 Support shaft 30a, 30b Steering clutch 32 Transmission body 60a, 60b Steering brake 61 Brake disc Pa, Pb Hydraulic piston

Claims (2)

[Claims] 1. A drive gear for driving a driving device, which is located on a lateral side of a rotatable center gear, a transmission that meshes with the driving device driving gear and is slidably fitted to a support shaft of the center gear, and runs from the center gear. Each of the steering clutches attached to the transmission body to turn on and off the rotational power transmission to the device to perform the body steering is provided, and a hydraulic piston slides while the transmission body is meshed with the traveling device drive gear. The traveling transmission for an agricultural work vehicle configured to operate so that a steering state in which the steering clutch is engaged and a steering state in which the steering clutch is disengaged appear. A shaft is rotatably connected to the center gear, and the steering clutch is connected to a support shaft portion of the support shaft which is located on the opposite side of the center gear with respect to the traveling device drive gear. Is provided between the transmission member, the traveling transmission apparatus agricultural vehicle is disposed on the opposite side to the center gear of the hydraulic piston relative to the traveling device driving gear. A steering brake for applying a braking force to a traveling device by pressing a brake disc integrally and slidably engaged with the transmission body to steer the vehicle body, and the hydraulic piston Sliding operation of the brake disk, the steering clutch is engaged and the steering brake is off, and the steering is in a straight running state; the steering clutch and the steering brake are off in a gentle turning steering state; 2. The traveling transmission device for an agricultural work vehicle according to claim 1, wherein the steering clutch is disengaged so that a sharp turning steering state in which the steering brake is engaged is displayed.