JP2001030779A - Transmission for tractor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmission for a tractor with or without a shuttle transmission, although both types have basically the same specifications, and obtain one which has the shuttle transmission simply by adding it to the one that does not have it. SOLUTION: In a power transmission passage for transmitting power from an engine to a wheel, a transmission for tractor is provided, in a mission case 2, with a main transmission 24 which shifts vehicle speed to a plurality of steps and a shuttle transmission 21 which has the same number of steps for forward movement and backward movement. The shuttle transmission 21 is assembled in a gear case 20 in advance and the gear case 20 is fixed to a partition 15 of the mission case 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a transmission for a tractor.

[0002]

2. Description of the Related Art When performing a front loader operation with a tractor, it is necessary to frequently switch between forward and backward traveling. In this work, in order to improve workability, it is preferable that the vehicle speed during forward movement and the vehicle speed during reverse movement be substantially the same. As a tractor transmission that satisfies such specifications, for example, one provided with a shuttle transmission described in JP-A-10-6792 is known. This conventional tractor transmission is a power transmission device that transmits power from an engine to wheels and includes a main transmission that shifts a vehicle speed to a plurality of speeds, and moves forward and backward to an entrance side or an exit side of the main transmission. And a shuttle transmission for switching between the vehicle speeds is provided so that the vehicle speed when moving forward is the same as the vehicle speed when moving backward.

Some conventional tractors do not have the shuttle transmission. Therefore, it is assumed that specifications differ between those equipped with the shuttle transmission and those without the shuttle transmission, so that they are designed differently and are different models.

[0004]

SUMMARY OF THE INVENTION In the prior art,
With and without the shuttle transmission, they were treated as separate models, which complicated management and the like in design, manufacture, and maintenance.
Accordingly, the present invention provides a shuttle transmission device that has basically the same specifications, with or without a shuttle transmission device, and simply adds a shuttle transmission device to a specification that does not have a shuttle transmission device. It is an object of the present invention to provide a tractor transmission that can be used as a tractor.

[0005]

In order to achieve the above object, the present invention takes the following measures. That is, a feature of the present invention is that, in a power transmission path for transmitting power from an engine to wheels, a main transmission that shifts the vehicle speed to a plurality of speeds, and a shuttle transmission that has the same number of forward and reverse speeds. In the transmission of a tractor having a transmission case and a transmission case, the shuttle transmission is assembled in a gear case in advance, and the gear case is fixed to a partition of the transmission case.

[0006] By adopting the above configuration, a tractor without a shuttle transmission can be provided with a shuttle transmission only by assembling a gear case in which the shuttle transmission is sub-assembled to a transmission case. Preferably, the gear case is divided into front and rear parts. Further, it is preferable that the divided gear case is integrated after the shuttle transmission is assembled, and is jointly fastened to a partition of the transmission case with a common mounting bolt.

Further, the transmission case is formed by partitioning a clutch chamber accommodating a main clutch for turning on and off the power from the engine and a transmission chamber accommodating the main transmission with a partition wall. A main clutch release fork is provided between the main clutch and the gear case and fixed to the partition wall in the chamber, and the fork is curved and formed so as to project toward the main clutch. With this configuration, the distance between the main clutch and the gear case can be reduced, and the transmission can be made compact.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. 5 and 6 are a plan view and a side view of a tractor according to an embodiment of the present invention. The tractor has an engine 1 in a front part, and a transmission case 2 is fixed to a rear part of the engine 1 to form a vehicle body. The vehicle body is supported by front wheels 3 and rear wheels 4, and the engine 1 is covered with a bonnet 5. An instrument panel 6 and an operation handle device 7 are provided at the rear of the bonnet 5.
Is provided. The rear wheel 4 is covered with a fender 8, and a cockpit 9 is provided between the left and right fenders 8. A PTO shaft (power take-out shaft) 10 protrudes from the rear end surface of the vehicle body.

A power transmission device for transmitting the power of the engine 1 to the rear wheels 4, the front wheels 3 and the PTO shaft 10 is provided in the transmission case 2, and a transmission is provided in the power transmission device. Below the instrument panel 6, a clutch pedal 11 for engaging and disengaging the main clutch is pivotally supported in a suspended manner so as to be able to swing back and forth. On the upper surface of the transmission case 2 between the operation handle device 7 and the cockpit 9,
A main shift operation lever 12 is provided, and the operation handle device 7 is provided.
Is provided with a shuttle shift operation lever 13, and an auxiliary shift operation lever 14 is provided beside the cockpit 9.

FIGS. 1 to 4 show the transmission case 2 and a power transmission device therein. The transmission case 2 is partitioned into a front clutch chamber 16 and a rear transmission chamber 17 via a first partition 15. In the transmission chamber 17, lubricating oil and hydraulic oil are stored at a predetermined level. Further, a second partition 18 is provided behind the mission chamber 17.
Is provided. A main clutch 19 and a gear case 20 are provided in the clutch chamber 16, and the gear case 20 is fixed to the first partition 15. A shuttle transmission 21 is accommodated in the gear case 20. The gear case 20 includes a front case 22 and a rear case 2.
It is divided into three parts.

In the transmission chamber 17, a four-speed main transmission 24, an auxiliary transmission 25 for switching between high speed and low speed, and a creep transmission 26 for switching to very low speed,
And, the front wheel drive device 27 is housed. And
A rear wheel drive unit, a PTO transmission, and the like, not shown, are provided at a rear portion of the transmission case 2. The main clutch 19 includes a flywheel 28 fixed to an end of a crankshaft of the engine 1, a clutch disc 30 pressed against an end face of the flywheel 28 by a pressure plate 29, and a pressing force applied to the pressure plate 29. And a release hub 32 for releasing the pressing of the spring 31.

The release hub 32 is fitted to a boss formed on the front surface of the front case 22 so as to be slidable in the front-rear direction. A PTO drive shaft 33 is directly connected to the axis of the flywheel 28, and the PTO drive shaft 3 is connected to the flywheel 28.
Reference numeral 3 extends backward through the gear case 20 and is connected to the PTO shaft 10 via a transmission (not shown). The main clutch 19 is provided with a cylindrical driven shaft 34 extending rearward, and the driven shaft 34 is fitted around the PTO drive shaft 33 coaxially so as to be relatively rotatable. The clutch disk 30 is fixed to the driven shaft 34. The front end of the driven shaft 34 is rotatably supported by the flywheel 28 via a bearing, and the rear end of the driven shaft 34 is rotatably supported by the front case 22 via a bearing. Is located in the gear case 20.

On the side wall of the clutch chamber 16, a clutch operating shaft 35 is rotatably supported with a left-right axis. A main clutch release fork 36 is fixed to the clutch operation shaft 35, and the forked end of the fork 36 is engaged with the release hub 32. The fork 36 is disposed between the main clutch 19 and the gear case 20 and is formed so as to be convex toward the main clutch 19. One end of the clutch operation shaft 35 projects outside from the clutch chamber 16, and the clutch pedal 11 is connected to the projection via a clutch lever 37 and a clutch rod 38 (see FIG. 6).

The conventional release fork 36 is bent and formed in a convex shape toward the rear. However, since the release fork 36 does not interfere with the gear case 20 by forming a convex shape toward the front, the main clutch 19 Therefore, the distance between the transmission and the gear case 20 can be reduced, and as a result, the length of the transmission in the front-rear direction can be reduced. The main clutch 19 normally transmits the power of the engine 1 to the driven shaft 34 via the clutch disc 30. To cut off the power transmission, the clutch pedal 11 is depressed. When the clutch pedal 11 is depressed, the clutch operating shaft 35 rotates via the clutch rod 38 and the clutch lever 37, the main clutch release fork 36 swings, the release hub 32 moves forward, and the diaphragm spring 31 To release the pressing force, the power transmission to the clutch disk 30 is cut off, and the driven shaft 34 enters a free state.

The gear case 20, which is divided into a front case 22 and a rear case 23, is sub-assembled with the shuttle transmission 21 therein, and is temporarily fixed by bonding the divided surfaces with an adhesive. Unite,
Then, it is fixed to the first partition 15 by a common bolt 39. By adopting such a configuration, the efficiency of assembly is improved. Further, the tractor without the shuttle transmission can be used as the tractor having the shuttle transmission 21 simply by assembling the gear case 20.

The shuttle transmission 21 in the gear case 20 has a forward / reverse switching clutch 40 provided at the rear end of the driven shaft 34 of the main clutch 19. This clutch 4
The back drive gear 41 is freely rotatably provided on the driven shaft 34 on the front side of the gear No. 0, and the back intermediate gear 42 meshes with the back drive gear 41 (see FIG. 2).
The back input gear 43 is meshed with. The back input gear 43 has a boss projecting forward, and the outer periphery of the boss is rotatably supported by the front case 22 via a bearing. A spline hole is formed in the axis of the back input gear 43. The reverse input shaft 44 is inserted into this spline hole so as to be freely inserted and removed, and is spline-coupled. The reverse input shaft 44 is disposed with an axis parallel to the driven shaft 34. The reverse input shaft 44 is rotatably supported by the rear case 23 via a bearing and extends rearward, and its rear end is supported by the second partition 18 via a bearing.

As described above, since the reverse input shaft 44 can be freely inserted into the reverse input gear 43, the shuttle transmission device 21 can be subassembled into the gear case 20. A forward input shaft 45 is disposed coaxially with the driven shaft 34 behind the forward / reverse switching clutch 40, and the forward input shaft 45 is rotatably supported by the rear case 23 via a bearing. I have. The forward input shaft 45 is formed as a cylindrical shaft, and is fitted around the PTO drive shaft 33 so as to be relatively rotatable.

The forward / reverse switching clutch 40 includes, for example,
It is a synchronous occlusion type clutch exemplified in Japanese Patent Publication No. 8-1221, and the shaft 34 is attached to the rear end of the driven shaft 34.
A hub 46 provided so as to be integrally rotatable with the hub 46, and a shifter 47 externally fitted to the hub 46 so as to be relatively non-rotatable and axially movable.
And a synchronization ring (not shown) arranged on both sides in the front-rear direction of the hub 46. The back drive gear 41 is provided with an engagement portion 48 that engages with the shifter 47 via the synchronization ring, and an engagement portion 49 that engages with the shifter 47 via the synchronization ring also on the forward input shaft 45. Is provided.

The shifter 47 includes a shift fork 5
0 is engaged. The shift fork 50 is provided on a rod 51 fixed between the front case 22 and the rear case 23 of the gear case 20 so as to be slidable in the front-rear direction. At the lower part of the front case 22, there is provided a protruding portion 52 which swells forward, and the shift fork operating shaft 53 is rotatably supported on the protruding portion 52 and the upper wall of the transmission case 2 in a vertical axis posture. Have been. The operation shaft 53 is provided behind the release fork 36 of the main clutch 19 and in front of the shifter 47 of the shuttle transmission 21. The operation shaft 53 includes an upper shaft 54 and a lower shaft 5.
5 are divided into upper and lower parts, and both parts are removably connected via a coupling 56. A yoke 57 is fixed to the lower shaft 55 inside the protruding portion, and a tip end of the yoke 57 is engaged with the shift fork 50.
The upper shaft 54 has an upper end protruding above the upper surface of the transmission case 2, and the shuttle speed control lever 13 is connected to the protruding end via a link (not shown). By operating the shuttle shift operation lever 13 provided on the operation handle device 7 in the front-rear direction, the operation shaft 5 is operated.
3 rotates, and the yoke 57 provided at the lower part swings in the front-rear direction. The swing of the yoke 57 moves the shift fork 50 in the front-rear direction, and moves the shifter 47 in the front-rear direction.

When the shifter 47 is at the intermediate position in the front-rear direction, the shifter 47 is in the neutral position. When the shifter 47 moves forward from the neutral position and engages with the engaging portion 48 of the back drive gear 41, the driven shaft 34 is transmitted to the reverse input shaft 44 via the back drive gear 41, the intermediate gear 42, and the back input gear 43. Conversely, when it moves backward from the neutral position and engages with the engagement portion 49 of the forward input shaft 45, the power of the driven shaft 34 is transmitted to the forward input shaft 45. As in the above configuration, the shift fork operation shaft 53 is set to the vertical axis posture,
Since the upper end portion and the shuttle shift operation lever 13 are connected, the connection between them can be performed with the shortest distance. In addition, since the operating shaft 53 is divided into upper and lower parts, the lower shaft 55 can be incorporated into the gear case 20, so that the shuttle transmission 21 can be easily made into a sub-assembly.

The PTO drive shaft 3 in the transmission chamber 17
3, a cylindrical output shaft 58 is fitted around the same shaft so as to be rotatable relative to each other. The front end of the transmission output shaft 58
The inner end of the forward input shaft 45 is rotatably supported via a needle bearing, and the rear end is rotatably supported on the second partition 18 of the transmission case 2 via a bearing. Forward input shaft 4 in the transmission chamber 17
5. The main transmission 24 for four-speed shifting is provided on the reverse input shaft 44 and the shift output shaft 58.

That is, the reverse input shaft 44 is provided with a first speed gear 60 and a second speed gear 61 so as to be freely rotatable from a rear portion to a front portion, and a third speed gear 62 and a fourth speed gear 62. Gear 63
Has been fixed. Between the first speed gear 60 and the second speed gear 61, a first and second speed switching clutch 64 is provided. The clutch 64 is provided with the forward / reverse switching clutch 40.
It is configured as a synchronous occlusion clutch having the same configuration as that of the first embodiment. That is, the first and second speed switching clutch 64 has a hub 65 fixed to the reverse input shaft 44, and a shifter 66 is fitted on the hub 65 so as to be movable in the axial direction, and is synchronized with both front and rear sides of the hub 65. A ring (not shown) is provided.
The first and second speed gears 60 and 61 are provided at their inner ends with engaging portions 67 and 68 that engage with the shifter 66.

Gears 69 and 70 which are always engaged with the first and second speed gears 60 and 61 are fixed to the transmission output shaft 24, and a gear 71 which is always engaged with the third speed gear 62 is relatively rotatable. Fitted outside. A gear 72 that is always engaged with the fourth speed gear 63 is formed at a rear portion of the forward input shaft 45. A third and fourth speed switching clutch 73 composed of a synchronous occlusion clutch is provided between the rear end of the forward input shaft 45 and the third speed gear 71 on the transmission output shaft 58.

That is, the third and fourth speed switching clutch 73 has a hub 74 fixed to the speed change output shaft 58.
A shifter 75 is fitted on the hub 7 so as to be movable in the axial direction.
Synchronization rings (not shown) are provided on both front and rear sides of 4. Further, at the rear end of the forward input shaft 45 and at the inner end of the third speed gear 71, engaging portions 76 and 77 that engage with the shifter 75 are provided. FIG. 7 shows a gear diagram of the shuttle transmission 21 and the main transmission 24 described above.

As shown in FIG. 3, the first and second speed shifter 66 and the third and fourth speed shifter 75 include a first and second speed shift fork 78 and a third and fourth speed shift gear. Each fork 79 is engaged, and each shift fork 7
Reference numerals 8 and 79 are respectively fixed to two shift rods 80 for switching the first and second speeds and a shift rod 81 for switching the third and fourth speeds, which are provided to be movable in the front-rear direction parallel to each other on the same horizontal plane. . Each shift rod 80, 81 is a PTO drive shaft 3
3 and the front and rear ends of the shift rods 80 and 81 are connected to the first and second partition walls 15 and 18 of the transmission case 2, respectively.
It is supported by. The main transmission operation lever 12
The lower end of the shift fork 78 or 79 is selectively engaged with one of the pair of shift forks 78 and 79, and the shift fork 78 or 79 on the engaged side is moved in the front-rear direction by operating the operation lever 12. It is possible.

Since the inner diameter of the first- and second-speed switching shifters 66 is larger than the outer diameter of the first-speed gear 60, when the shifter 66 is shifted to the first-speed side, the first- and second-speed switching shifters 66 pass through the engaging portion 67 and the first. There is a risk of going too far (overshift) to the speed gear 60 side. Therefore, as shown in FIG.
In order to prevent overshifting of the shifter 66 for 2-speed switching,
A notch 82 is formed at the end of the shift rod 80 for switching between the first and second speeds.
And the transmission case 2 is provided with a stopper pin 83 that engages with the step of the notch 82. The stopper pin 83 is screwed into a ball insertion hole 84 opened for inserting an interlock ball between the two shift rods 80, 81, so that the transmission case 2
Attached to.

At the rear of the transmission output shaft 58, a low-speed gear 85 and a high-speed gear 86 are arranged in a row from the rear to the front so as to be able to rotate integrally with the transmission output shaft 58. A transmission shaft 87 is provided in the transmission case 2 in parallel with the transmission output shaft 58. A front end of the traveling shaft 87 is rotatably supported by a rear case 23 of the gear case 20 via a bearing, and an intermediate portion thereof is rotatably supported by the second partition 18 via a bearing. Rear wheel drive differential device (not shown)
Is being entered.

The traveling shaft 87 has an ultra-low speed input gear 88, a low speed gear 89,
A high-speed gear 90 and an ultra-low-speed output gear 91 are relatively rotatably provided, and a front wheel drive gear 92 is fixed in front of the gear. Low speed gear 89 and high speed gear 90 on running shaft 87
Are the low-speed gear 85 and the high-speed gear 86 of the transmission output shaft 58.
And always mesh with. The ultra low speed input gear 88 and the low speed gear 89 on the traveling shaft 87 are configured as a double gear. Further, an intermediate shaft 93 parallel to the traveling shaft 87 is rotatably provided on the transmission case 2 via a bearing. The intermediate shaft 93 is provided with an ultra-low speed input gear 88 and an ultra-low speed output gear 91. Gear 9 that always meshes
4, 95 are provided so as to be integrally rotatable.

The traveling shaft 87 between the low-speed gear 89 and the high-speed gear 90 is provided with a high-low speed switching clutch 96. The high / low speed switching clutch 96 is an occlusal clutch, and includes a hub 97 fixed to the traveling shaft 87 and a shifter 9 fitted to the hub 97 so as to be relatively non-rotatable and movable in the axial direction.
8 is provided at an inner end of the low-speed gear 89 and the high-speed gear 90 with an engagement portion that engages with the shifter 98. The traveling shaft 87 on the front side of the ultra-low speed output gear 91 is provided with an ultra-low speed switching clutch 99. The ultra low speed switching clutch 99 is an occlusal clutch, and includes a hub 100 fixed to the traveling shaft 87, and a shifter 101 externally fitted to the hub 100 so as to be non-rotatable and axially movable. An engagement portion that engages with the shifter 101 is provided at an inner end of the low-speed output gear 91.

As shown in FIG. 3, shift forks 102 and 103 are engaged with the high / low speed switching shifter 98 and the ultra low speed switching shifter 101, respectively. The high / low speed switching shift fork 102 is provided with a shift rod 102a.
The yoke 102b (see FIG. 1) which engages with the rear end of the shift rod 102a is swung by the operation of the auxiliary speed change operation lever 14 shown in FIG.
02 moves forward and backward. Further, the ultra low speed switching fork 103 is also fixed to the shift rod 103a.
03a is operated in the front-rear direction by operating an operation lever (not shown).

The sub-transmission 25 is constituted by the low-speed gears 85 and 89, the high-speed gears 86 and 90, the high-low speed switching clutch 96 and the like, and the ultra-low-speed gears 88, 91, 94 and 95 are provided. The creep transmission 26 is constituted by an ultra-low speed switching clutch 99 and the like. The front wheel drive gear 92 meshes with the output gear 105 via the intermediate gear 104. The output gear 105 is connected to an output shaft 106 via a front wheel drive clutch 107 so as to be freely turned on and off. The front end of the output shaft 106 is input to a front-wheel drive differential device (not shown).

Thus, the front wheel drive device 27 is constituted by the front wheel drive gear 92, the front wheel drive clutch 107 and the like. The lubricating oil stored in the transmission chamber 17 is scraped up by the rotation of the gear, and
The oil is supplied to the lubricating oil of the transmission and the like in 7, and is pumped up by a hydraulic pump to be used as hydraulic oil for various actuators. The return oil of the hydraulic oil is supplied from a rear portion of the shift output shaft 58 to a gap between the PTO drive shaft 33 and the shift output shaft 58, flows forward, and is used for lubrication of a synchronous occlusion clutch or the like. . Then, the fluid flows out from the front end of the transmission output shaft 58, lubricates the forward / reverse switching clutch 40, and is stored in the gear case 20.

The rear case 23 of the gear case 20 is provided with an oil communication hole 108 as shown in FIG. The oil in the gear case 20 returns to the transmission chamber 17 through the oil communication hole 108.
However, this oil communication hole 108 is provided at a position higher than the lubricating oil storage level in the mission chamber 17 and
The lubricating oil level in the gear case 20 is higher in the transmission chamber 1
7 is higher than the lubricating oil level. According to the embodiment having the above-described configuration, a tractor having a shuttle transmission can be provided by merely using the same transmission case and attaching the gear case 20 to the tractor without the shuttle transmission. Further, in the shuttle transmission 21, the length of the transmission in the front-rear direction is shortened by eliminating the need for the conventional reverse gear train.

The present invention is not limited to the embodiment described above, but can be applied to, for example, a type in which a shuttle transmission is provided downstream of the main transmission.

[0035]

According to the present invention, the transmission case can be shared between a tractor with and without a shuttle transmission, and when a shuttle transmission is added, a gear case in which the shuttle transmission is sub-assembled can be used. Since it is only required to assemble, design, manufacturing and maintenance are simplified.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a transmission showing an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG. 1;

FIG. 3 is a sectional view taken along the line BB of FIG. 1;

FIG. 4 is a plan view of a transmission case.

FIG. 5 is a plan view of the tractor.

FIG. 6 is a side view of the tractor shown in FIG. 5;

FIG. 7 is a gear diagram of the transmission shown in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine 2 Transmission case 15 Partition wall 16 Clutch room 17 Transmission room 19 Main clutch 20 Gear case 21 Shuttle transmission 22 Front case 23 Rear case 24 Main transmission 36 Release fork 39 Bolt

Claims (4)

[Claims] In a power transmission path for transmitting power from an engine to wheels, a main transmission that shifts a vehicle speed to a plurality of speeds and a shuttle transmission that has the same number of forward and reverse speeds are provided in a transmission case. The transmission for a tractor, wherein the shuttle transmission is assembled in a gear case in advance, and the gear case is fixed to a partition of the transmission case. 2. The tractor transmission according to claim 1, wherein the gear case is divided into front and rear parts. 3. The split gear case according to claim 2, wherein after assembling the shuttle transmission, the divided gear case is integrated and fastened to a partition of the transmission case with a common mounting bolt. Tractor gearbox. 4. The transmission case is formed by partitioning a clutch chamber accommodating a main clutch for turning on and off the power from the engine and a transmission chamber accommodating the main transmission with a partition wall. A main clutch release fork is provided between the main clutch and the gear case, and is fixed to the partition wall in the chamber;
The transmission of a tractor according to any one of claims 1 to 3, wherein the fork is curved and formed so as to be convex toward the main clutch.