JPH09109916A - Steering turning control of combine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To select the turning mode necessary according to the condition of the steering turning, and to improve the working efficiency, by providing a change-over switch to convert the operation of a turning clutch in the transmission of various sorts of turning modes, at the inner side position inner than a projection end edge, at the upper side of a change-over lever guide. SOLUTION: A turning change-over lever 3 to convert a gear transmission to a slow turning mode to turn by reduction driving a crawler at the steering side than a crawler at the outer side, or to a spin turn mode to turn by reverse rotation driving the crawler at the steering side to the crawler at the outer side; and its change-over lever guide 4; are projected at one side near an operating seat. At the upper side of the change-over lever guide 4, and at the inner side position inner than the projection end edge 4b, a turning change-over switch 5 to convert the operation of a turning clutch in the transmission of the slow turning mode and the spin turning mode is provided. Consequently, a turning mode necessary according to the condition of the steering turning can be selected, and the working efficiency can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering control system for a combine, including a swing switching lever for switching gear transmission between a slow swing mode and a spin swing mode, and a swing switching switch for switching a swing clutch in the both swing modes. It can be used for those provided with.

[0002]

2. Description of the Related Art When performing a steering turn in a headland or the like at the end of a field during the operation of a combine, there is a brake turning mode for performing a normal turn by brake braking on the steering side, A slow-turning mode in which a slow-turning drive on the steering side makes a gentle large-turn turn, and a spin-turning mode in which a sharp small-turn turn is made by a reverse rotation drive on the steering side are switched appropriately according to field conditions. Is already known.

Conventionally, when each of the turning modes is switched to the slow turning mode or the spin turning mode, conventionally, the gear transmission of the traveling mission case is switched by operating the turning switching lever, and the turning switching lever is switched. When engaging the operation and automatically turning on the slow swing switch or the spin swing switch and also switching the electric circuit of the swing clutch at the same time, the tilt angle when operating the power steering lever reaches a certain tilt angle when braking. With a position that automatically performs a gentle turn or a spin turn at a set position, the power steering is performed regardless of the state of the steering turn when performing work or field conditions, such as turning and split cutting in addition to reciprocating cutting. When braking by lever operation, it automatically switches to gentle turning or spin turning,
It became an improper turning, which also hindered work efficiency.

In view of this, the present invention is to provide a turning guide switch for stopping the execution of turning in the slow turning mode or the spin turning mode in the lever guide of the turning switching lever.

[0005]

SUMMARY OF THE INVENTION According to the present invention, a brake turning mode A in which a steering brake 2 is applied to a steering side crawler 1 to make a turn, and a steering side crawler 1 is placed on an outer crawler. In the combine that can be switched to a slow swivel mode B in which the vehicle is decelerated more than 1 to turn, and a spin swirl mode C in which the steering side crawler 1 is swiveled in the reverse direction to the outer crawler 1 to swivel A swivel switching lever 3 and a switching lever guide 4 for switching the gear transmission to the swivel mode B or the spin swivel mode C are provided in a protruding manner on one side in the vicinity of the operation seat 18, and a projecting end is formed on the upper surface 4a of the switching lever guide 4. Edge 4b
The steering turning control device is provided with a turning changeover switch 5 for switching the action of the turning clutch 43 in the transmission of the turning modes B and C at an inner position.

[0006]

With the above-described structure, when the steering turn is performed on the headland of the field at the time of the combine operation, the brake turn mode A is used to turn the brake turn to a certain inclination angle by operating the power steering lever. When the power steering lever reaches a certain tilt angle and the turning changeover switch 5 is ON, the turning clutch 43 is engaged, and when the turning changeover lever 3 is changed over to the gentle turning mode B side, it is automatically turned on. A gentle turn is performed, and when the turn switching lever 3 is switched to the spin turn mode C side, the spin turn is automatically performed. When it is necessary to stop the execution of the turning at the time of the slow turning or the spin turning, for example, a triangular switching for guiding the operation of the turning switching lever 3 to a position on the left side wall near the operation seat 18 where it is easy to operate. By turning off the turning changeover switch 5 provided on one side of the inclined upper surface 4a of the lever guide 4,
When the turning clutch 43 is disengaged, the brake turning can be resumed.

As described above, when the power steering lever reaches a certain tilt angle during the steering turning in the brake turning mode A, the turning changeover switch 5 is turned on to change the turning to the slow turning mode B or the spin turning mode C. Since it can be executed or stopped by an OFF operation, it is possible to select the required turning mode according to the state of the steering turning at that time, and it is possible to improve work efficiency by appropriate turning. . In addition, by mounting the swivel changeover switch 5 at a position where it does not protrude from the outer protruding edge 4b (when viewed from the front) of the inclined switch lever guide 4 upper surface 4a, erroneous operation due to contact with the operator's knee or thigh is avoided. can do. Further, by inclining the upper surface 4a of the switching lever guide 4, it is possible to suppress the overhang of the protruding edge 4b, which is an obstacle to the operator, as short as possible.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. A traveling device 7 having a pair of left and right crawlers 1 for traveling on the soil surface is disposed below the undercarriage 6 of the combine, and threshed grain culm supplied to the undercarriage 6 by being sandwiched by a feed chain 8. Then, a threshing apparatus 10 having a grain tank 9 for selectively collecting the threshed grains and temporarily storing the threshed grains is mounted. At the front side of the threshing device 10, a weeding body 11 for weeding the raised culm from the front end position, a raising part 12 for causing the weeded culm, and a cutting blade part 1 for cutting the caused cereal culm.
3 and transport the harvested culm backwards to
A mowing device 15 having a grain culm transporting part 14 for delivery to the dochen 8 is suspended and supported on the front end of the chassis 6 by a mowing suspension part 16 so as to be vertically rotatable and can be raised and lowered with respect to the soil surface. An operating device 17 for controlling the operation of the combine and an operating seat 18 for this operation are provided on one side of the reaping device 15, and an engine 19 is mounted below the operating seat 18 to the rear of these. The grain tank 9 is arranged, the traveling device 7, the threshing device 10, and the cutting device 1 are arranged.
5, the operating device 17, the engine 19 and the like constitute a combine vehicle body 20.

A traveling mission case 21 is mounted on the front end side of the chassis 6, and a gear transmission mechanism is provided inside the mission case 21. This gear transmission mechanism is
As shown in FIGS. 3 and 4, a shift gear groove 23a into which a shift shifter 25 that is slidable left and right by a shifter stay 24 is fitted is provided in a double shift gear 23 that rotates about an input shaft 22 as a first shaft. By the action of the shift shifter 25, the shift gear 23 and the counter shaft 26 as the second shaft
A high-speed gear 27 and a low-speed gear 28, which are axially locked to each other, are interlocked and interlocked with each other, and a transmission gear 29 is horizontally and axially fixed to the counter shaft 26, and a steering shaft 30 as a third shaft.
A sub gear shift is constituted by interlocking two steering center gears 31 that are axially locked with each other so as to transmit the shift power between the high speed side (running speed) and the low speed side (working speed) by the counter shaft 26.

Clutch pawls 31b for meshing are provided on both side surfaces of the steering center gear 31, respectively. Clutch pawls 32b meshed with and connected to the clutch pawls 31b on the side surface of the gear portion 32a are arranged close to the left and right clutch pawls 31b. The left and right steering clutches 32 each having a left and right steering shafts 32 are respectively supported by the steering shafts 30, and the left and right steering clutches 32 are respectively provided on the opposite extension parts of the clutch pawls 32b. 2 is engaged and provided, and the return spring 50 of the steering clutch 32 is internally provided in this extension portion.
A shifter groove 32c into which the left and right steering shifters 33 for sliding the steering clutch 32 to the left and right are respectively inserted is provided between the 2a and the extended portion.
3a of the clutch claws 31b and 3b
The steering clutch 32 is disengaged, and the steering clutch 32 is disengaged, and the steering brake 2 is braked at the same time by disengaging the clutch claws 31b and 32b from the side where the steering clutch 32 is engaged. It is configured to act on the side.

One of the small diameter gears 31a of the two steering center gears 31, a slowly rotating gear 35 which is idled by a rotating shaft 34 as a sixth shaft, and a idle bearing by a reduction shaft 36 as a fourth shaft. The two small diameter gears 37a of the two spin intermediate gears 37 are meshed and interlocked with each other, and the other large diameter gear 37b of the spin intermediate gear 37 and the rotating shaft 34
The spin swivel gear 38, which is supported on the free swivel shaft, is meshed and interlocked, and between the slow swivel gear 35 and the spin swivel gear 38,
A switching clutch 39 having clutch pawls 39a on both sides is arranged, and a switching shifter 40 for sliding the clutch 39 left and right is fitted into the switching clutch 39.
b is provided, and by the action of the switching shifter 40, one of the clutch claws 39a and one of the clutch claws 35a and 38a provided on each side surface of the two swivel gears 35 and 38 is provided.
It is configured to be engaged and connected separately.

Each gear portion 3 of the left and right steering clutches 32
2a and two left and right steering power transmission gears 41 which are idled by the reduction shaft 36 are meshed with each other, and left and right swivel transmission gears 42 are idled by the swivel shaft 34, respectively. The left and right turning clutches 43 for axially rotating the transmission gear 42 are axially stopped, and the left and right turning transmission gears 42 are rotated.
And the left and right two turning intermediate gears 45, which are idler bearings on the turning intermediate shaft 44 as the seventh shaft, are engaged with each other, and one small diameter gear 45 of the left and right turning intermediate gears 45 is engaged.
a and the left and right steering transmission gears 41 are in mesh with each other.

One small diameter gear 41a of the two left and right steering transmission gears 41 and the left and right wheel shafts 46 as a fifth shaft.
The left and right wheel gears 47 fixed to one end of the left and right wheels mesh with each other in interlock with each other, and the left and right driving wheels 48 for driving the left and right crawlers 1 are respectively fixed to the other ends of the left and right wheel shafts 46. Configure. A power steering lever 51 for performing left-right steering and turning in the traveling direction of the vehicle body 20, and a connecting rod 52 connected to the lower portion of the power steering lever 51 as shown in FIG.
However, by rotating the lever 51 up and down by tilting the lever 51 left and right, a rotating plate 54 that rotates left and right around the fulcrum shaft 53
And a detection plate 54 arranged in an L shape of the rotating plate 54.
By the action of a, the variable switch 56 for controlling the variable throttle valve 55 of the hydraulic power steering circuit, which will be described later, and the swing execution switch 57 for executing the slow swing or the spin swing are turned ON / O.
It is arranged so that FF is possible, and the timing of this ON is configured such that the variable switch 56 acts earlier than the turning execution switch 57, and a position sensor such as a potentiometer for detecting the left or right tilt position of the power steering lever 51. 58 is engaged with the lever 51. 59
Is a return spring. The power steering lever 51 is arranged on the upper right side of the operating device 17.

As shown in FIG. 6, a main shift lever 60 for switching between forward and backward movement of the vehicle body 20 and a main shift of the vehicle speed, and a sub shift lever 61 for switching the vehicle speed between a high speed side and a low speed side are provided.
A main / secondary lever guide 62 provided on the upper left side in front of the operation seat 18 also serves as a cover, so that the main speed change lever 60 is located in the front side main lever guide groove 62a and the auxiliary speed change lever 61 is located in the rear side sub lever guide groove 62b. The main lever lever 60 and the sub-lever 6
Each of them is rotatably supported by the auxiliary lever rotating plate 61a. The main lever rotating plate 60a and the sub-lever rotating plate 61a are connected to one ends of a main speed change rod 63 and an auxiliary speed change rod 64, which extend toward the lower side of the operating seat 18, respectively. The other ends of 63 and the auxiliary transmission rod 64 are connected to one ends of a bell crank 65 and an arm crank 66, respectively.

The slow swing gear 35 and the spin swing gear 38
A switching switching lever 3 for operating a switching clutch 39 for switching between and is provided so as to project outward at a position where a left side wall 67 provided in contact with the inner side wall 62c of the main / sub lever guide 62 is easily operated. A turning changeover switch 5 for guiding and arranging the turning guide 43 in the lever guide groove portion 4c of the inclined upper surface 4a of the lever guide 4 is provided.
On one side of the upper surface 4a of the switching lever guide 4, the relative position with the projecting end edge 4b protruding outward is as shown in FIG.
It is configured by mounting and arranging so that there is a relationship between the angle θ and the distance a. The turning changeover switch 5 may be a push-button type which is turned on when it is turned on, and the type is not limited to the present invention as long as it does not deviate from the gist of the present invention.

As shown in FIG. 8, the mission case 2
1. A shifter shaft 33 of a steering shifter 33 that causes the left and right steering clutches 32 to project outwardly from the front wall 21a of No. 1
The left and right clutch arms 68 that are axially fixed to a are attached to the front wall 2
The left and right clutch sensors 7 which are rotated by the operation of the left and right steering cylinders 69 arranged in 1a and detect this rotation.
0 is arranged.

A controller 71 is provided near the operating device 17 for controlling the arithmetic operation of each automatic circuit mainly by a CPU,
As shown in FIG. 9, a turning changeover switch 5, a variable switch 56, a turning execution switch 57, a position sensor 58, left and right clutch sensors 70, etc. are connected to the input side of the controller 71, and the left and right sides are connected to the output side thereof. Steering solenoid valve 72 for operating the steering cylinder 69 of the steering clutch 32, a swinging clutch solenoid valve 73 for operating the left and right swinging clutches 43, and braking of the steering brake 2 accompanying disengagement of the left and right steering clutches 32. The pressure relief solenoid valves 74 for suppressing the pressure are connected to each other.

The steering hydraulic circuit S for driving the turning in the brake turning mode A and the turning hydraulic circuit T for driving the turning in the slow turning mode B or the spin turning mode C have different circuit configurations, and the steering is performed. As shown in FIG. 10, the hydraulic circuit S supplies the pressure oil supplied from the hydraulic pump 76 from the same oil tank 75 that operates the hydraulic continuously variable transmission H, the harvesting device 15 and other hydraulic systems to the steering clutch. Via the solenoid valve 72, one side of the left and right steering cylinders 69 that actuate the left and right steering clutches 32 and the steering brake 2 is switchably connected so as to be able to send or return oil. Connection is made to return oil from the other side of the cylinder 69 to the oil tank 75 via the pressure relief solenoid valve 74 and the variable throttle valve 55 or the fixed throttle 77.

The swing hydraulic circuit T is, as shown in FIG.
The left or right swing clutch 43 is operated by pressure oil supplied from the transmission case 21 by a hydraulic pump 84 so that the swing clutch electromagnetic valve 73 can switch between oil supply and oil return. The gear transmission in the traveling transmission case 21 is based on the input shaft 2.
When the power is transmitted to the low-speed gear 28, the dual transmission gears 23 of the input shaft 22 are slid left and right, and when the high-speed gear 27 is rotated by the countershaft 26, the high-speed gear 27 is interlocked with the low-speed gear 28. At this time, the transmission is shifted to a low speed, and the shifted power is transmitted to the countershaft 26 similarly to the transmission gear 2 which rotates.
9, the steering center gear 3 that rotates about the steering shaft 30
Link to 1.

When turning in the brake turning mode A during this interlocking, the turning selector switch 5 is turned off and the pressure relief solenoid valve 74 is connected to the power steering circuit side. In this state, for example, when the power steering lever 51 is tilted leftward, this tilt position is detected by the position sensor 5
3 by the action of the variable throttle valve 55 of the power steering circuit by turning on the variable switch 56 that engages with the connecting rod 52 connected to the lever 51, and the switching of the steering clutch solenoid valve 72 to the left, Left steering cylinder 69
The left steering shifter 33 is actuated by this action, and by this action, the clutch pawl 31b of the steering center gear 31 and the clutch pawl 32b of the left steering clutch 32 are disengaged and the steering shaft 30 is rotated. At the same time that the steering clutch 32 that is running freely rotates, the left steering brake 2 is further braked.

By this braking, the rotation of the two left steering transmission gears 41 idled on the reduction shaft 36 interlocking with the gear portion 32a of the steering clutch 32 is stopped and the steering center gear 31 is rotated. To the right steering transmission gear 41 from the steering clutch 32 on the right side, and further, from one small diameter gear 41a of the steering transmission gear 41 to the right driving wheel 48 via the right wheel gear 47. Interlock. The driving of the right crawler 1 by the right driving wheel 48 and the braking of the left steering clutch 32 cause the left crawler 1 in the braking state to make a left turn. .

Next, when the speed change transmission gear 29 is linked to the steering center gear 31, the swing switching lever 3 is switched to the gentle swing mode B side so that one small diameter gear 31a of the steering center gear 31 is linked. The clutch claw 35a of the slow-turning gear 35 that freely rotates on the turning shaft 34 and the clutch claw 39a of the switching clutch 39 that rotates axially are meshed and connected by the switching shifter 40 to rotate the slow-turning gear 35 axially. When the power switch lever 51 is tilted to the left while the turning switch 5 is in the ON state due to the axial rotation of the slow turning gear 35, the left steering brake 2 is operated by the same action as the stroke in the brake turning mode A. Is braked and the braking state is detected by the clutch sensor 70, so that the pressure relief solenoid valve 74 is switched to the bypass circuit side, and the fixed throttle 77 of this bypass circuit is switched.
The turning execution switch 5 that holds the disengagement of the steering clutch 32 by this action and engages the connecting rod 52 connected to the lever 51 in a state where the steering brake 2 is not braked.
When 7 is turned on, the left turning clutch 43 is turned on by the turning clutch electromagnetic valve 73, and the left turning transmission gear 42, which idles from the slow turning gear 35, is axially rotated. From the turning transmission gear 42, the turning intermediate shaft is rotated. 44, via the left-hand two turning intermediate gears 45 idling, the left-hand turning gears 41 are idled by the disengagement of the steering clutch 32. The small-diameter gear 41a of the reference numeral 41 passes through the left wheel gear 47 to drive the left drive wheel 48 to decelerate the left crawler 1 relative to the right crawler 1, thereby slowly turning to the left. To perform.

Next, when the speed change transmission gear 29 is interlocked with the steering center gear 31, the turning switching lever 51 is switched to the spin turning mode C side so that one of the small diameter gears 31a of the steering center gear 31 moves from the reduction shaft. 36 and the small-diameter gear 37a of the two spin intermediate gears 37 which rotate freely, and are rotated from the large-diameter gear 37b to rotate the swivel shaft 3
4 is interlocked with the spin swivel gear 38 that idles, and by this inversion, the clutch claw 38a of the spin swivel gear 38 that reversely rotates with respect to the slow swivel gear 35 and the clutch claw 39a of the switching clutch 39 that axially rotates. The spin shift gear 38 is axially rotated by meshing connection by the switching shifter 40. When the power switch lever 51 is tilted to the left while the turning selector switch 5 is in the ON state due to the axial rotation of the spin turning gear 38, the left steering brake 2 is operated by the same action as the stroke in the brake turning mode A described above. And the clutch sensor 70 detects this braking state to switch the pressure relief solenoid valve 74 to the bypass circuit side and hold the disengagement of the steering clutch 32 by the action of the fixed throttle 77 of the bypass circuit. ,
The lever 51 is set in a state where the steering brake 2 is not braked.
When the turning execution switch 57 that engages with the connecting rod 52 connected to is turned on, the left turning clutch 43 is turned on by the turning clutch electromagnetic valve 73, and the left turning transmission gear 42 that idles from the spin turning gear 38 is rotated. By rotating and driving the left drive wheel 48 to drive the left crawler 1 in the reverse rotation with respect to the right crawler 1, a spin turn to the left is performed.

The swivel switching lever 3 for switching between the slow swivel mode B and the spin swirl mode C is a lever guide groove portion 4c of a switching lever guide 4 projecting inward at a position near the mission case 21 on the left side wall 67. Is operated to smoothly operate, and the turning clutch solenoid valve 73 for switching the action of the turning clutch 43 is turned on / of.
The swivel changeover switch 5 to F is set to the changeover lever guide 4
Since it is attached to the upper surface 4a close to one end of the lever guide groove 4c and at a position where it does not protrude from the protruding edge 4b of the upper surface 4a, inadvertent erroneous operation due to contact of the operator's knees or thighs during work is avoided. be able to. In addition,
Since the upper surface 4a of the switching lever guide 4 is inclined, the protruding edge 4b can be kept as short as possible so as not to interfere with the operator.

Further, as shown in FIG. 6, the main transmission lever 60
The bell crank 65 connected to the end of the main speed change rod 63 extending from the engine and the arm crank 66 connected to the end of the auxiliary speed change rod 64 extending from the auxiliary speed change lever 61 are adjacent to each other, and 19. Both adjustment screws 63a, 64 are arranged centrally in an adjustable range from the opening of the radiator cover 78 located in the storage part 19 and adjust the lengths of the ends of the rods 63, 64 respectively.
By providing a structure with a, both rods 63, 6
When the length of 4 is adjusted, the radiator cover 78 is simply opened and the adjustment screws 63a and 64 are opened from the opening.
With a, adjustment can be performed simultaneously and easily. Therefore, there is no need for various troublesome operations as in the conventional case.

As shown in FIG. 12, the bell crank 65 of the main transmission rod 63 and the arm crank 66 of the auxiliary transmission rod 64 are adjacent to each other so as to be positioned at right angles to each other.
By providing a cutout portion 65a in a part of the outer shape of the bell crank 65 and a bulging portion 66a in a part of the outer shape of the arm crank 66, when the sub-shift is switched to the high speed side, the main shift is performed by the bell shift. The crank 65 has a cutout portion 65a.
Is locked by the bulging portion 66a of the arm crank 66 and is prevented from rotating, so that it is not possible to switch to the reverse side, and when the main shift is switched to the reverse side, the arm crank 66 is used for the auxiliary shift. Since the bulging portion 66a is locked by the outer peripheral portion of the bell crank 65 other than the notch portion 65a to prevent the rotation, the switching to the high speed side becomes impossible. In this way, the back restraint device is attached to the bell crank 65.
Notch portion 65a and bulge portion 66a of arm crank 66
It is possible to simply and inexpensively construct by the engagement mechanism with.

As a different embodiment from the above, a belt type continuously variable transmission for switching between forward and backward movements and speed change of a vehicle by a combination of a belt speed change and a planetary gear is shown in FIG.
As shown in, the flat step portion 80 is provided in the neutral area N of the cam surface 80a of the speed change cam 80 for adjusting the pulley diameter of the speed change pulley 79.
By providing f, the shift cam 80 that presses and rotates the fixed roller 81 moves the moving pulley 79a of the shift pulley 79 with respect to the fixed pulley 79b to adjust the pulley diameter to a larger or smaller value. At this time, the flat step portion 80f provided in the neutral region N of the shift cam 80 during this shift can reliably and stably maintain the neutral region N regardless of play of the shift lever 82, defective return, and the like. With such stable holding of the neutral range N, as shown in FIG. 13, in order to cover the instability of maintaining the neutral range N, it is necessary to actuate the tension clutch with a combination of the neutral switch and the motor. Therefore, it is possible to avoid the disadvantage that the cost becomes excessive and the time lag at the time of starting and the clutch noise are generated.

As another means for stably maintaining the neutral area N, as shown in FIG. 15, by providing a relief groove 80h in the neutral area N of the cam surface 80a of the speed change cam 80, the neutral area N Since the tension of the belt 83 is slightly weakened, the reverse torque from the crawler 1 increases the braking force, and the speed change pulley 79 and the planetary gear portion are balanced with each other, so that the neutral range N can be stably maintained.

[Brief description of the drawings]

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

FIG. 2 is a front sectional development view showing a gear transmission mechanism of the traveling transmission case.

FIG. 3 is a front array diagram showing a gear transmission mechanism of a traveling transmission case.

FIG. 4 is a side array diagram showing a gear transmission mechanism of the traveling transmission case.

FIG. 5 is a schematic front view showing an operating state of each switch by the power steering lever.

FIG. 6 is a perspective view showing an arrangement state of respective levers in the vicinity of an operation seat.

FIG. 7 is a front view showing a mounting state of a turning switch.

FIG. 8 is a partial front view showing an operating state of a clutch sensor.

FIG. 9 is a block diagram showing an electric circuit for automatic control.

FIG. 10 is a block diagram showing a hydraulic circuit for operating a brake turning mode.

FIG. 11 is a block diagram showing a hydraulic circuit that operates a gentle turning mode and a spin turning mode.

FIG. 12 is an operation diagram showing a back restraining state by engagement of the connecting cranks of both shift levers.

FIG. 13 is an operation diagram showing a conventional state of a shift cam in a belt continuously variable transmission according to another embodiment.

FIG. 14 is an operation diagram showing an improved state of the shift cam in the belt continuously variable transmission according to another embodiment.

FIG. 15 is an operation diagram showing an improved state of the shift cam in the continuously variable belt transmission according to another embodiment.

[Explanation of symbols]

 1. Crawler 2. Steering brake 3. Turning switch lever 4. Switching lever guide 4a. Upper surface 4b. Projected edge 5. Turning switch 18. Operator's seat 43. Swing clutch

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshitomo Goto, No. 1 Yakura, Tobe Town, Iyo-gun, Ehime Prefecture

Claims (1)

[Claims] 1. A brake swivel mode A in which a steering brake 2 is applied to a steering side crawler 1 to turn, and a steering side crawler 1 is driven with a deceleration drive as compared with an outer crawler 1. In the combine that can be switched to the slow turning mode B that is turned on and the spin turning mode C in which the steering side crawler 1 is driven to rotate reversely with respect to the outer crawler 1, the slow turning mode B or the spin turning mode C A swivel switching lever 3 and a switching lever guide 4 for switching the gear transmission to the side are projectingly provided on one side in the vicinity of the operation seat 18, and the swivel is performed on the upper surface 4a of the switching lever guide 4 to a position inside the projecting edge 4b. A steering turning control device provided with a turning changeover switch 5 for switching the action of the turning clutch 43 in transmission of modes B and C.