JPH0586161B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a clutch operating device for a work vehicle such as a combine harvester, and more particularly to the structure of a clutch operating device for operating a friction clutch using a hydraulic actuator.

(b) Prior Art Generally, in work vehicles such as combine harvesters, fine speed control is performed by operating a continuously variable speed lever, etc. in response to field conditions and reaping conditions. The forward and reverse clutches are operated by hydraulic actuators controlled by solenoid valves.

(c) Problems to be Solved by the Invention For this reason, when the aircraft starts traveling, the clutch connects with an impact, making it impossible to start smoothly through a half-clutch state. In addition, when trying to stop accurately at a predetermined position or performing detailed work at a slow speed, it may be difficult to control speed using a continuously variable transmission lever or steering control using a side clutch. It is desired that a means for speed control be developed.

Therefore, the present invention provides a clutch operating device that enables a half-clutch state by controlling the actuator that operates the friction clutch with a variable relief valve that is linked to an emergency stop clutch pedal, thereby solving the above-mentioned problems. The purpose is to provide

(d) Means for solving the problem The present invention has been made in view of the above circumstances, and as shown in FIGS.
A variable relief valve V10 is connected to an oil path that supplies hydraulic pressure to switching valves V8 and V9 that control hydraulic actuators FA and RA that operate the hydraulic actuators FA and RA.
Furthermore, in conjunction with the emergency stop clutch pedal 55 that operates the variable relief valve V10 in an emergency, based on the operation of the clutch pedal 55, the friction clutch 75 is half-clutched by controlling the variable throttle of the variable relief valve V10. Configure it so that it can be manipulated into a state.

Further, for example, the friction clutch 75 may be forward and reverse clutches 75f and 75r operated by the continuously variable speed lever 4.

(E) Effect Based on the above configuration, when the operator depresses the clutch pedal 55, the variable relief valve V
10 is subjected to variable throttle control, and the oil pressure of the oil passage 71 sent to the switching valve V8 or V9 is changed.
Then, use the pressure oil to actuator FA or RA.
is controlled, the pressing force of the clutch 75 is manipulated. As a result, the operator can adjust the pressure on the clutch pedal 55 to
Clutch 75 can be operated into a half-clutch condition.

(F) Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

As shown in FIG. 11, the combine C has a body 17 supported by left and right crawlers 15L and 15R (see FIG. 3) driven by left and right sprockets SR and SL. An engine 19 is mounted on one side at the rear, a driver's seat 7 is arranged at one side at the front, and a grain tank 29 is also installed. Further, a preprocessing section 23 is disposed at the front of the body 17 so as to be movable up and down. The driver's seat 7 has a driver's seat frame 24 fixed on the fuselage frame 17a, and a step surface 2 on the front part of the frame 24.
5 is fixed, and a brake/travel clutch pedal 55 is installed at its front end. On the other hand, as shown in FIG.
7 is installed, a fuel tank 21 is further arranged in the driver's seat frame 24, and a seat 27 is installed.
A valve body 31 is placed and fixed on the lower driver's seat frame 24. The valve body 31 has a block 31a in which a predetermined oil passage is formed, and the block 31a is fixed on the driver's seat frame 24. Solenoid valve V1 for continuously variable transmission, solenoid valve V2 for Zyde clutch, solenoid valve V3 for lowering the pre-processing section, solenoid valve V4 for raising the same, solenoid valve V5 for unloading, valve V6 for manually lowering the pre-processing section, solenoid for the brake. valve V7,
A solenoid valve V8 for the forward hydraulic clutch, a solenoid valve V9 for the reverse hydraulic clutch, a variable relief valve V10 for the clutch pedal, and a filter F are provided.

Further, an operation console 11 is erected above the front portion of the driver's seat frame 24, and the upper surface of the operation console 11 serves as an operation panel 9. A monolever 1 is provided upright on the operation panel 9, and various operation switches, meters, and display lamps are also provided. The monolever 1 is configured to be able to swing in two steps only in the left and right direction, and the first step of the movement moves the lever 1 itself relative to a lever box installed at its rotating base, thereby operating a limit switch. Furthermore, it controls the side clutch solenoid valve V2 and operates the side clutch actuator A to disconnect the left and right side clutches, and the second stage of the movement moves the lever box together with the lever 1. The variable relief valve 22 is controlled to control the braking pressure of the left and right side brakes (see Fig. 1). On the other hand, the shaft supported within the operation console 11 has left and right side clutch levers 5L,
5R is rotatably supported in the front-back direction, and the base end portions of the levers 5L and 5R are respectively linked to a side clutch/brake in the transmission case 26 via a link mechanism. Further, as shown in FIG. 2, a side operation panel 10 is disposed adjacent to the inside of the aircraft body of the driver's seat 7, and on this panel 10 are provided a hydraulic lever 2, an F/R continuously variable transmission lever, Furthermore, an engine control lever 51 (see FIG. 11) is arranged at the front end of the panel 10, and a threshing clutch lever and a pre-processing lever are arranged along the far side of the seat. The clutch lever is located at the front. The hydraulic lever 2 is swingably supported by a pin 52 and connected to the valve body 3 via a link mechanism 54.
By controlling the manual lowering valve V6 and the manual raising valve V4 of the pre-processing section 1, the actuator 23A for the pre-processing section 23 can be controlled to move up and down (see FIG. 1). Also,
The F/R continuously variable transmission lever 4 is swingable in the left and right directions and is biased to a vertical position and is supported by a pivot plate 4a.
It is supported so that it can swing freely in the longitudinal direction of the fuselage through the
It can be operated throughout the reverse range and neutral position. Furthermore,
A potentiometer 56 is interlocked with the pivot plate 4a portion of the continuously variable transmission lever 4, and the meter 56 operates the continuously variable transmission solenoid valve V1 that operates the actuator 57A for the belt type continuously variable transmission 57, and the transmission. The solenoid valves V8 and V9 that actuate the forward and reverse hydraulic clutch actuators FA and RA in the case 26 are controlled (see Fig. 1) to provide stepless speed change control in forward and reverse directions, as well as in neutral. At this point, disengage both the forward and reverse clutches to bring them to the neutral state. Further, the sub-shift lever 6 is pivotally supported by a pin 59, and further has a link mechanism 60.
The transmission gear can be switched between high speed and low speed in conjunction with the auxiliary transmission gear arm 61 of the transmission case 26 via the transmission case 26. Furthermore, the pivot pin 5 of the sub-shift lever 6
A pre-processing section gear change lever 62 is pivotally supported at 9, and the lever 62 is connected to a pre-processing section shift gear arm 65 of the transmission case 26 via a link mechanism 63.
In conjunction with this, the pre-processing section transmission gear can be switched. The belt-type continuously variable transmission 57 is configured such that an endless belt d is wound between the driving side split pulley 33 and the driven side split pulley 35. and,
The driving side split pulley 33 has a movable sheave 36 and a fixed sheave 37, as shown in FIGS. 4 and 5.
The boss portion 36a of the movable sheave 36 is slidably fitted to the shaft 40. Further, the hydraulic actuator 3 is in contact with the back surface of the movable sheave 36 via a bearing 30, and a groove 37b is formed on the outer periphery of the fixed sheave 37, around which an endless belt e for transmitting rotation from the engine 19 is wound. ing. Further, the end of the shaft 40 is rotatably fitted into the counter case 16 and connected to a hydraulic pump P fixed to the case 16, and the hydraulic pump P is operated by the rotation of the shaft 40. It is configured as follows.

On the other hand, the driven side split pulley 35, as shown in FIG. The boss portion 41a is slidably fitted thereto. Furthermore, the movable sheave 41 has a rear surface 41a thereof.
is pressed by a return spring s, and presses the endless belt d interposed between the movable sheave 41 and the fixed sheave 42. The cover 45, which is in contact with one end of the return spring s, is fixed to the outer periphery of a sleeve 46 that is fitted into and fixed to a fitting hole 26a formed on one side of the upper part of the mission case 26. Further, the shaft 43 is rotatably supported within the mission case 26 by a bearing. Mission case 26
The transmission 24 includes a pretreatment system drive section 64, a hydraulic clutch section 75 for forward/reverse movement, a side clutch/brake device 94, etc.
The shaft 43 has a spline-coupled gear 47, and the sleeve shaft 4
9 is inserted through the needle. Further, the sleeve shaft 49 has three gears 50a, 50b, 51 with different numbers of teeth, and the gear 50
Of the gears 67 and 72 rotatably fitted into the shaft 66 rotatably supported by the case 26 in the pretreatment system drive section 64, the gear 50b meshes with the smaller diameter gear 67, and the gear 50b has the smaller diameter. It meshes with gear 72. These gears 67 and 72 are switched by a shifter 68 operated by an arm 65, and rotation is transmitted to a shaft 66. Additionally, a one-way clutch 74 is provided at one end of the shaft 66.
A pulley 73 is provided to transmit rotation in one direction to the preprocessing section 23 via an endless belt.

On the other hand, a hydraulic clutch section 75 is located below the shaft 43 and includes a forward hydraulic clutch 75f and a reverse hydraulic clutch 75r, each of which is a friction clutch, with both ends of its rotating shaft g supported by bearings. There is. Furthermore, a large-diameter gear 76 is spline-coupled to one end of the rotating shaft g, and a forward gear 76 is connected to the forward clutch 75f.
7 and a gear 78, and a back gear 79 is fixed and arranged on the reverse clutch 75r, respectively.
Further, as shown in FIG. 1, forward and reverse clutch actuators FA and RA act on the forward clutch 75f and the reverse clutch 75r.
are in communication with the forward hydraulic clutch valve V8 and the reverse hydraulic clutch valve V9, respectively,
It also communicates with a variable relief valve V10 arranged in a low pressure system oil passage 71 together with a parking brake valve V7 that acts on a parking brake actuator BA. The forward hydraulic clutch 7
5f and the reverse hydraulic clutch 75r are configured so that their respective hydraulic fluids are discharged and the clutches are disengaged by pressing the clutch pedal 55, which controls the variable relief valve V10 via a link mechanism. Furthermore, after the clutch is disengaged,
By further pressing the clutch pedal 55,
A wire W connected to the pedal 55 (see FIG. 9)
The left and right multi-disc brakes BL and BR are braked and activated by towing the vehicle. Further, the gear 78 is meshed with the gear 51, and the forward gear 78 is in mesh with the gear 51.
7 is meshed with a gear 81 splined to one end of a shaft 80. Furthermore, a gear 82 is spline-coupled to the other end of the shaft 80 and an idle gear 83 is supported via a needle. It is meshed with a gear 87 fixed to the positioned shaft 85. Furthermore, a transmission gear 90 consisting of a small diameter gear 90a and a large diameter gear 90b is slidably supported at the center of a shaft 89 disposed adjacent to the shaft 85, and at both ends thereof. Gears 91 and 92 are spline-coupled, and gear 91 is connected to gear 8 of shaft 80.
2 and the gear 92 is the gear 86 of the shaft 85.
The forward and reverse rotations based on the forward and reverse hydraulic clutches 75f and 75r are transmitted to the shaft 89, respectively.

Left and right steering shafts 93l and 93r are rotatably arranged at the lower stage of the shaft 89, and a center gear 96 consisting of a large-diameter gear 96a and a small-diameter gear 96b is rotatably arranged between them. has been done. And these large diameter gears 96
a and 96b are small diameter gears 90 of the transmission gear 90;
A and 90b are switched and meshed as appropriate. Further, the left and right steering shafts 93l and 93r have left and right multi-plate brakes BL and BR at their respective ends, and are rotatably supported at their central portions by bearings. As shown in detail in FIG. 6, the left steering shaft 93l has a left dock gear 99.
1 is slidably supported, and a gear 97l is fitted and fixed. Also, the left dock gear 9
9l has a groove 99a over its entire outer periphery, has a back surface 99b pressed by a return spring p, and is engaged with a dock claw 96c formed in the center of the center gear 96. .
Furthermore, below the left steering shaft 93l, as shown in detail in FIG. 7, a clutch shifter shaft 100 extends in a plane orthogonal to the steering shaft 93 and is rotatably supported by a case at both ends. At the center of the shaft 100, a shifter arm 1 is provided with hook-shaped claws 101a and 102a at its tip.
01 and 102 are fixed facing each other, and these arms 101 and 102 have their claw portions 101a,
102a fits into the groove 99a so as to sandwich the dock gear 99l from both sides. Further, as shown in FIGS. 8 and 9, an arm 105 having a rotatably provided sleeve 103 at its tip is fixed to one end of the clutch shifter shaft 100. One end of the pin 106 is slidably fitted into the fitted hole 103a. Further, a brake operation shaft 107 is rotatably disposed adjacent to the left multi-disc brake BL, and a bell crank-shaped arm 109 is spline-coupled to the end of the shaft 107. A sleeve 110 rotatably installed at one end of the sleeve 110 has a fitting hole 110a, and the pin 10 is inserted into the fitting hole 110a.
The other end of 6 is slidably fitted, and
A predetermined number of spacer rings 104 are interposed on the pin 106 between the sleeves 103 and 110. Then, connect both ends to the sleeve 10.
3 and 110, respectively, the insertion holes 103a and 110
The pin 106 fitted in the spacer ring 1
The sleeves 103 and 110 slide left and right within the range regulated by 04 to constitute a play mechanism that transmits the rotational force of the arm 105 in the counterclockwise direction in FIG. 8 to the arm 109. This constitutes a relief mechanism that does not transmit the clockwise movement in FIG. 8, that is, the movement in the brake activation direction, to the arm 105. Further, a bolt 111 is fixed to the other end of the arm 109. A bifurcated pressing arm 112 is fixed to a position of the brake operation shaft 107 adjacent to the left multi-disc brake BL, and is adapted to press the left multi-disc brake BL by rotation of the shaft 107. There is. Note that on the right multi-disc brake BR side, similarly to the left multi-disc brake BL described above, a bifurcated arm 113 that presses the right multi-disc brake is fixed to a shaft 115, and a bell is attached to the tip of the shaft 115. An arm 117 is fixed in the shape of a crank and has a bolt 116 at one end. and,
A sleeve 119 having a fitting hole 119a is pivotally supported at the other end of the arm 117. Further, an arm 1 is provided at the tip of the shaft 120 which is disposed opposite to the clutch shifter shaft 100.
21 is fixed, and a sleeve 122 having a fitting hole 122a is pivotally supported at its tip. A spacer ring 104 is interposed between the sleeve 122 and the sleeve 119, and the pin 12
3 are slidably fitted from both sides to form a play mechanism and a relief mechanism. In addition, the shaft 1
20 is provided with arms 124 and 128 at its center, similar to the clutch shifter shaft 100 (see FIG. 3). The bell crank-shaped arms 109, 117 and the play/relief mechanism are housed in a cover H provided on the front side of the case 26, and inside the cover H, as shown in FIGS. 7 to 9, A shaft 125 is rotatably disposed extending in a direction perpendicular to the shaft 107, and a sleeve 126 is fixed to the center portion of the shaft 125, and a sleeve 127 is connected to a spline at the distal end of the shaft 125. combined. A rotating plate 129 is joined to the outer peripheral surface of the sleeve 127, and a wire fixing portion 129b of a bent portion 129a formed on the rotating plate 129
A wire W is connected to. The wire W is connected to the aforementioned brake/travel clutch pedal 55, and when the pedal 55 is depressed, a variable relief valve V10 is controlled, and a hydraulic actuator is actuated on the forward and reverse hydraulic clutches 75f and 75r. The rotating plate 129 is pulled when the FA and RA hydraulic oil is discharged and the clutch 75f or 75r is disengaged. Further, a plunger 132 of a parking brake actuator BA fixed to a fixed plate 131 joined to a bracket 130 is in contact with the flat portion of the rotating plate 129.
Further, the sleeve 126 has a pressing plate 133, and as the shaft 125 rotates, the pressing plate 133 presses the bolts 111 of the arms 109, 117,
Press 116 at the same time.

On the other hand, as shown in FIG. 7, an arm 135 is fitted and fixed to the clutch shifter shaft 100 adjacent to the arm 102, and is perpendicular to the shaft 100 facing the claw portion 135a formed at the tip thereof. A hydraulic actuator A for operating a side clutch/brake device 94 extending in a plane is arranged. The hydraulic actuator A has a single piston 20, as shown in FIGS. 135a. Further, in the center of the piston 20, there is a pressing plate 139 that presses the claw portion 137a of the arm 137 that acts on the right multi-plate brake.
It is fixedly installed opposite to 36. Further, the arm 137 is connected to the other clutch shifter shaft 1.
It is fixed to the end of 20. Further, left hydraulic cylinders 2 are provided at both ends of the piston 20, respectively.
0L and right hydraulic cylinder 20R are arranged facing each other, and these left and right hydraulic cylinders 20L, 20
R and the piston 20 constitute a hydraulic actuator A. Furthermore, these left and right cylinders 20
Oil passages 20c, 20d and 20e, 20f are formed in L and 20R, respectively, and the piston 2
0 begins to operate on the left multi-disc brake BL or the right multi-disc brake BR with hydraulic oil, the oil passage 20c becomes the oil passage 20d, and the oil passage 20e becomes the oil passage 20.
f, and the oil passages 20d and 20f each communicate with one variable relief valve 22 (see FIG. 1), so that the left and right brakes BL,
BR braking pressure is controlled.

Then, as shown in FIG. 3, the left and right steering shafts 9
Shafts 141l, 14 adjacent to 3l, 93r
1r are arranged rotatably, and gears 142l, 143l and gear 14 are provided at both ends of each of these shafts 141l and 141r.
2r and 143r are fixed. Further, the gear 143l meshes with the gear 97l, and the gear 143r meshes with a gear 97r that is fitted and fixed to the right steering shaft 93r similarly to the gear 97l. Furthermore, a right dock gear 99 is located at a position adjacent to the center gear 96 of the right steering shaft 93r.
r is pressed against the center gear 96 by a return spring q, and is provided so as to be able to slide freely. The left and right sprockets SL and SR that drive the left and right crawlers 15L and 15R are connected to the shaft 1.
It is spline-coupled to one end of each of left and right axles 145l and 145r rotatably disposed adjacent to 41l and 141r. Further, gears 146l and 146 having the same number of teeth are provided at the other end of each of the left and right drive shafts 145l and 145r.
r is fixedly installed, and these gears 146l, 14
6r are meshed with the gears 142l and 142r, respectively.

Next, the hydraulic circuit will be explained with reference to FIG.

The hydraulic pump P communicates with a flow divider 69 via a filter F, and is divided into a high pressure system 70 and a low pressure system 71 by the flow divider 69. The high pressure system 70 includes an unload valve V5, a pretreatment section raising valve V4, a pretreatment section lowering valve V3, a pretreatment section manual lowering valve V6,
A side clutch valve V2 and a continuously variable transmission valve V1 are connected in parallel. Note that the pretreatment section raising valve V4 is used both during manual operation and during automatic control using an ultrasonic sensor, etc., but the lowering solenoid valve V3 performs inching control, etc., and is therefore used only during automatic control. In addition, a manual lowering valve V6 is installed for manual operation using the hydraulic lever 2. Further, the parking brake valve V7 is in communication with the parking brake actuator BA, and when the continuously variable transmission lever 4 is operated in neutral, the valve V7 is automatically operated, and the actuator BA is operated to control and operate the parking brake. It is made to be. In addition, 29' in the figure is the hydraulic system for the grain tank 29 and 29'.
A is the actuator for the grain lifting cylinder.

Next, the operation of this embodiment will be explained.

The rotation transmitted to the fixed sheave 37 of the driving side split pulley 33 by the drive of the endless belt e based on the engine output is transmitted to the continuously variable transmission 5 consisting of the driving side split pulley 33, the endless belt d, and the driven side split pulley 35.
7 to the shaft 43. and,
The rotation of the shaft 43 is transmitted by a gear 47 to a rotating shaft g of a hydraulic clutch portion 75 via a gear 76. Then, based on the operation of the continuously variable transmission lever 6 to the forward range, the forward clutch valve V8 is switched, and when the forward clutch actuator FA is activated and the forward clutch 75f is connected, the engine 19 rotates forward. The signal is transmitted to the idle gear 81 through the gear 77 and further transmitted to the gear 91 via the idle gear 82. Then, the transmission gear 90 is rotated together with the gear 91, and by timely switching the gear 90 based on the auxiliary transmission lever 6, the small diameter gear 90a is changed to the large diameter gear 96a of the center gear 96.
, and from the large diameter gear 90b to the center gear 9
The rotation is transmitted to each of the 6 small diameter gears 96b. Further, based on the operation of the continuously variable transmission lever 6 to the reverse range, the reverse clutch valve V9 is switched, and when the reverse clutch actuator RA is operated and the reverse clutch 75r is connected, the rotation of the engine 19 is shifted to the reverse gear. The signal is transmitted to the idle gear 83 at 79, and further transmitted to the coaxial gear 86 via the gear 87. Then, the rotation is transmitted from the gear 86 to the gear 92, and the transmission gear 90 is rotated. Further, by switching the transmission gear 90 appropriately, the small diameter gear 90a is transferred to the gear 96a of the center gear 96, and from the large diameter gear 90b to the center gear 96. The rotation is transmitted to each small diameter gear 96b of the gear 96. Also, the engine 1
The center gear 96, which has received the normal rotation or reverse rotation from the center gear 9, transmits the rotation via the dock claws 96c and 96d to the dock gears 96l and 99r, which are pressed against each other by return springs p and q from both sides thereof.
At this time, the forward clutch valve V8 and the reverse clutch valve V9, which control the forward clutch 75f and the reverse clutch 75r, are communicated with a variable relief valve V10, respectively, and the valve V10 is also used as a brake for traveling. Since it is connected to the clutch pedal 55 via a link mechanism, the clutch pedal 5 is operated by the operator.
5, the residual pressure of the hydraulic cylinders FA and RA is controlled based on the variable relief valve V10.
The forward and reverse clutches 75f, 75r can be operated in a half-clutch state.

On the other hand, by tilting the monolever 1 by one step to the left, the side clutch valve V2 is activated, and as shown in FIG. When the oil is sent, the piston 20 pushes the claw portion 135a of the arm 135 onto the pressing plate 1, as shown in FIG. 10b.
36, the oil passage 20c moves to the right while pressing and rotating, and as shown in FIG.
It stops at a position connected to 0d. The shaft 100 is then rotated by the rotation of the arm 135 as the piston 20 moves to the communication position. Then, the shifter arms 101 and 102 fixed to the central portion of the shaft 100 are rotated in the direction of the left multi-disc brake BL, and the dock gear 99l is moved against the return spring p. and,
The dock gear 99l is removed from the dock claw 96c of the center gear 96, and the left side clutch is disconnected. In this case, an arm 105 fixed to one end of the shaft 100 together with arms 101 and 102
Although the arm 105 is also rotated, the rotation of the arm 105 is not transmitted to the arm 109 due to the play mechanism consisting of the sleeves 103 and 110, the pin 106, and the spacer ring 104. In addition, when the monolever 1 is operated to tilt to the second stage, the variable relief valve 22 communicated with the oil passage 20c is subjected to a variable throttle operation, and the pressure of the pressure oil sent to the left cylinder 20L is increased. Piston 20 is moved further to the right. Then, as the arm 135 is further rotated by the pressing plate 136, the arm 105 fixed to the tip of the shaft 100 is rotated greatly, and the sleeve 103 is brought into contact with the sleeve 110 along the pin 106, The force from arm 105 is transmitted to arm 109, which is rotated together with brake operating shaft 107. Then, the arm 112 on the shaft 107 is rotated together with the shaft 107 in the direction of the left multi-disc brake BL, and the arm 112 presses the left brake BL to perform braking and operation.

On the other hand, when the monolever 1 is operated to the right to the first stage, the side clutch valve V2 is operated in the same manner as when the monolever 1 is operated to the left, and pressure oil is supplied to the right hydraulic cylinder 20R from the oil passage 20e. is sent, the piston 20 moves toward the left cylinder 20L, and is stopped at a position where the oil passage 20e communicates with the variable relief valve 22 via the oil passage 20f. As the piston 20 moves to this position, the arm 137 is rotated by the press plate 139 and the shifter arms 124 and 128 are rotated in the direction of the right multi-disc brake BR, so that the dock gear 99r is moved from the center gear 96. It is removed from the dock claw 96d,
The right side clutch is disconnected. In this case, the arm 121 also rotates together with the shifter arms 124 and 128, but the sleeves 119 and 122 and the pin 123
The rotation of the arm 121 is not transmitted to the arm 117 due to the play mechanism formed by the spacer ring 104. When the monolever 1 is operated to the right to the second stage, the variable relief valve 22 is throttled, the actuator 20 is further moved toward the left cylinder 20L, and the arm 137 is rotated significantly. Then, as the arm 137 largely rotates the arm 121 via the shaft 120, the arm 117 is rotated, and the shaft 11 is further rotated.
5, the arm 113 presses the right multi-disc brake BR to perform braking and operation.

In addition, the brake/travel clutch pedal 5
5 is pressed by the operator in an emergency, etc., the variable relief valve V is activated via the link mechanism.
10 is opened, hydraulic oil is discharged from the forward clutch actuator FA or reverse clutch actuator RA, and the forward clutch 75f or reverse clutch 75r is disengaged. and,
After these clutches 75f and 75r are disconnected,
When the pedal 55 is further depressed, the wire W connected to the pedal 55 moves to the fixed part 129 of the rotating plate 129.
b, and the shaft 1 together with the rotary plate 129.
Further, as the shaft 125 rotates, the pressing plate 133 fixed to the sleeve 126 rotates, and simultaneously presses the bolts 111 and 116 of the arms 109 and 117 at both ends thereof. The pressing causes both arms 109 and 117 to rotate, and further rotates arm 112 and arm 113 to press and brake the left and right multi-plate brakes BL and BR, respectively. Further, when the parking brake valve V7 is automatically operated and the parking brake actuator BA is activated when the continuously variable transmission lever 4 is operated in neutral, the plunger 132 of the actuator BA is activated.
By pressing and rotating the pressing plate 129, the left and right multi-plate brakes are activated in the same way as when pulling the wire W.
Brakes and operates BL and BR at the same time. When an emergency or neutral brake operation is performed via these wires W and actuator BA, the sleeves 110 and 119 disposed at the ends of the rotating arms 109 and 117, respectively,
Since these arms 109 and 117 move in the opposite direction to the sleeves 103 and 122, which are connected via pins 106 and 123, these arms 109 and 117 do not affect the side clutch side, and the arms 112 and 1
13, it acts only on the left and right multi-disc brakes BL and BR.

On the other hand, when the monolever 1 is not tilted to the left or right, rotation is transmitted to the left dock gear 99l from the center gear 96 via the dock pawl 96c, and further to the large diameter gear 143l via the gear 97l that rotates together with the left dock gear 99l. is rotated. The rotation of the gear 143l is caused by the shaft 1
41l to a gear 142l and a gear 146l, and the gear 146l further transmits the signal to a drive shaft 145.
1. The left sprocket SL is rotated, and the left crawler 15L is driven. Also, right dock gear 99
Similarly to the left dog gear 99l, r also has the center gear 9.
The rotation is transmitted to the right sprocket SR via the gear 97r, the large diameter gear 1443r, the gear 142r, and the gear 146r, and the right crawler 15R is driven.

(G) Effects of the Invention As explained above, according to the present invention, the hydraulic actuators FA and RA that operate the clutch 75
The variable relief valve V10 is connected to the oil passage 71 that supplies pressure oil to the switching valves V8 and V9 that control the switching valves V8 and V9, and the variable relief valve V10 is linked to the emergency stop clutch pedal 55. By strongly pressing the pedal 55, the work vehicle can be brought to an emergency stop, and the clutch is activated via the hydraulic actuators FA and RA based on variable throttle control of the variable relief valve V10 by adjusting the pressure on the clutch pedal 55. The pressing force of the clutch 75 can be controlled as desired, and the clutch 75 can be easily and quickly brought into a half-clutch state when necessary. This allows work vehicles such as combine harvester C to start smoothly when they start traveling, and enables fine speed control, allowing detailed work to be done at a slow speed and precise positioning. It is possible to easily stop the vehicle.

Further, the friction clutch 75 is replaced by a forward and reverse clutch 75 operated by the continuously variable speed lever 4.
If f, 75r is used, there is no need to separately provide a special clutch, the structure becomes simple, and both the forward clutch 75f and the reverse clutch 75r can be in a half-clutch state, which allows the combine harvester C, etc. This work vehicle can be operated with a half-clutch in both forward and reverse motions.

[Brief explanation of the drawing]

Fig. 1 is a hydraulic circuit diagram according to the present invention, Fig. 2 is a cross-sectional view of the driver's seat of the combine as seen from the rear of the seat, Fig. 3 is a cross-sectional view showing the entire transmission to which the present invention can be applied, and Fig. 4 The figure is a cross-sectional view showing the drive pulley of the continuously variable transmission, Figure 5 is a side view showing the continuously variable transmission part, Figure 6 is an enlarged cross-sectional view of the side clutch/brake part, and Figure 7 is the transmission. Fig. 8 is a sectional view taken along the - line in Fig. 7, Fig. 9 is a sectional view taken along the - line in Fig. 8, and Figs. 10 a, b, and c show different operating states of the hydraulic actuator. FIG.
FIG. 11 is a side view showing the entire combine harvester. 19...Engine, 55...Emergency stop clutch pedal (brake-cum-driving clutch pedal), 71
...Oil passage (low pressure system oil passage), 75...Friction clutch (hydraulic clutch part), FA, RA...Hydraulic actuator (clutch actuator for forward and reverse movement), V8~
V9...Switching valve (forward/reverse hydraulic clutch valve), V10...Relief valve (variable relief valve), C...Work vehicle (combine harvester).

Claims (1)

[Scope of Claims] 1. In a work vehicle having a friction clutch that transmits power from the engine to the traveling system, and in which the clutch is operated by a hydraulic actuator, a switching valve that controls the hydraulic actuator is provided with pressurized oil. A variable relief valve is communicated with an oil path for supplying the friction clutch, and the variable relief valve is linked to an emergency stop clutch pedal, and based on the operation of the clutch pedal, the variable relief valve is subjected to variable throttle control to stop the friction clutch. A clutch operating device for a work vehicle configured to be able to operate a clutch into a half-clutch state. 2. A clutch operating device for a work vehicle according to claim 1, wherein the friction clutch is a forward and reverse clutch operated by a continuously variable speed lever.