JPS5939622B2 - Transmission device for agricultural tractors - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a transmission device for an agricultural tractor,
The purpose is to provide a new transmission device that changes the driving state of the working equipment according to the vehicle speed of the agricultural tractor, and provides a constant working state regardless of the vehicle speed. It is an object of the present invention to provide a new transmission device that is easy to install.

Regarding the illustrated embodiment, to explain the configuration of the transmission device in the agricultural tractor according to the present invention, as shown in FIG. The rear wheels 2 are forcibly driven, and the aircraft is steered by an operator seated on a seat 3 by rotating the front wheels 5 using a bundle 4. A hydraulic lift device 8 equipped with a lift arm 8a is attached to the rear of the machine to connect a working machine 6, which is a fertilizer applicator or a seeding machine, with a coupling device 7, and to raise and lower the working machine 6 via the coupling device I. Hopper 9 and the hopper.

-9 The working machine is configured to include a rotating drum 1θ with a pocket 10a provided in contact with the lower end frontage, and a delivery tube 11 extending downward from the delivery end of the rotating drum 10. The PTO shaft 13 is interlocked and connected 14 to the shaft 12 of the rotating drum 10 at 6, and the rotating drum 10 is driven to rotate in the direction of arrow S while the machine is running, and the fertilizer or seeds in the hopper 9 are transferred to the pockets of the rotating drum 10. l
In an agricultural tractor that is configured to carry Oa into the cylindrical body 11 and apply fertilizer or sow seeds,
This invention is implemented as follows.

In other words, as shown in FIG.
Inside, as shown in FIG. 2, a traveling power transmission device 17 and a work machine power transmission device 18, both of which are configured as a hydraulic clutch type transmission device, are provided.

Of these, the traveling power transmission 11 is the engine 1
The working machine power transmission device 18 is disposed between a drive shaft 19 that is interlocked and connected to the drive shaft 19 and a transmission shaft 20 that is disposed below the drive shaft 19 in parallel with the drive shaft 19. A drive shaft 22 which is interlockingly connected via an intermediate shaft 21 and parallel to the PTO shaft 13 and a PTO shaft 3 spaces apart are provided, and each of the transmission devices 17 and 18 has the following configuration. It is considered a thing.

That is, first, the traveling power transmission 17 includes an F1 speed change gear 23 and an F2 speed change gear 2 that are fitted onto the drive shaft 19.
4, F3 speed change gear 25 and R speed change gear 26, and transmission shaft 2
The free rotating gears 27-30 are loosely fitted to the gears 27-30 through bearings on the drive shaft 19, and are meshed directly with the corresponding speed change gears 23-26 on the drive shaft 19 or indirectly through the R intermediate gear 31 (not shown). The F1 idler gear 27, the F2 idler gear 28, the F3 idler gear 29, the R idler gear 30, and the idler gears 27-30 are arranged on the transmission shaft 20, and their operation causes each idler gear 27 to -30 to the transmission shaft 20 selectively, an F1 hydraulic clutch 32, an F2 hydraulic clutch 33, an F3 hydraulic clutch 34, and an R hydraulic clutch 35. Due to this operation, the drive shaft 19 moves the transmission shaft 20 forward in one series F1.
, 2 forward speed F2, 3 forward speed F3, or 1 reverse speed R, and the transmission shaft 20 is interlocked and connected to the rear wheels 2 via a transmission mechanism (not shown).

Further, the work machine power transmission device 18 includes a first speed change gear 36 and a second speed change gear 3 which are fitted on the drive shaft 22 and have mutually different diameters.
The 7th and 3rd speed gears 38 and the corresponding gears 36- on the drive shaft 22 are loosely fitted through the PTO shaft 1 and 3 rings.
1st speed idling gear 39 meshed with 38. 2nd speed idling gear 40
and a 3rd speed idler gear 41, which is disposed above each idler gear 39-41 on one axis of the PTO shaft, and by its operation, selectively moves each idler gear 39-41 between one axis and three of the PTO shafts. A first-speed hydraulic clutch 42, a second-speed hydraulic clutch 43, and a third-speed hydraulic clutch 44 are provided.The drive shaft 22 drives the PTO shaft to three speeds by selectively operating the hydraulic clutches 42-44. , 2nd or 3rd speed.

As described above, according to the present invention, the gear ratios of each gear stage that controls the forward gear shift in the above-mentioned traveling power transmission device 1T and the gear ratios of each gear stage in the work machine power transmission device 18 are particularly mutually compatible with each other according to the present invention. is set at a certain ratio.

That is, the forward movement 1 determined by the gear ratio between the F1 speed change gear 23 and the F1 idle gear 27 in the traveling power transmission 17
Set the gear ratio to 11. F2 speed change gear 24 and F2 idle gear 2
The gear ratio at forward 2nd speed is determined by the gear ratio of 8 and 12, F.
The forward 3rd speed gear ratio determined by the gear ratio between the 3rd speed gear 25 and the F3 idler gear 29 is 13, and the 1st speed change gear 36 and the 1st speed idler gear 39 in the work machine power transmission 18.
The gear ratio during 1st gear shifting determined by the gear ratio of 11', 2
The 2nd speed gear ratio is determined by the gear ratio between the speed change gear 37 and the 2nd speed induction gear 40, and the 3rd speed is determined by the gear ratio between the 3rd speed change gear 38 and the 3rd speed idle gear 41. If the gear ratio during shifting is 13', then 11/11'=12/12'=i3/1A-k (constant)
...(1).

And, the traveling power transmission device 1T configured as above
The speed change operation between the work machine power transmission device 18, that is, the control operation for supplying and discharging hydraulic oil to and from the hydraulic clutches 32-35 and 42-44 is performed by the following mechanism. .

That is, each of the hydraulic clutches 32-35 and 42-44 has a clutch housing 45, 45' fitted onto the shaft 20.13, as also shown in FIG.
One friction plate 46, 46' is provided on the clutch housing 45, 45' so as to be slidably supported in the clutch axial direction, and each free rotating gear 27-30 and 39-41
The other friction plate 47, 4γ is provided so as to be slidably supported only in the clutch axial direction at its boss portion, and the piston 49, 49 is biased to move in the backward direction by return springs 48, 48'. ' and the oil chamber behind it Q, 0
Both friction plates 4 are moved forward by the action of pressure oil on the
The piston 49.49' engages between 6.46' and 47.47' to operate the clutch, and supplies and discharges hydraulic oil to and from the hydraulic clutches 32-35 and 42-44. This is performed via a hydraulic circuit as shown in FIG.

That is, in FIG. 3, 50 is mission case 1.
5 is an oil tank configured using the lower part of the inside, 51 is an oil pump that is mounted on the front of the mission case 15 and is driven by the engine 1, and a hydraulic clutch whose oil pressure is set by a pressure regulating valve 53. Oil supply circuit 54 to 32-35
As shown in the figure, the neutral position N and the F1 hydraulic clutch 3 are
Forward 1 in which only 2 is refueled and only the clutch 32 is actuated
forward speed position F1, forward second speed position F2 where oil is supplied only to the F2 hydraulic clutch 33 and only the clutch 33 is actuated, and F3.
A switching valve 55 is provided with five positions: a forward third speed position F3 where oil is supplied to only the hydraulic clutch 34 and only the clutch 34 is operated, and a reverse position R where oil is supplied only to the R hydraulic clutch 35 and only this clutch 35 is operated. The position of the switching valve 55 is selectively switched by an operating lever 56 to switch the gear stage of the traveling power transmission 17, and the oil pressure is set by a pressure regulating valve 57. The oil supply circuit 58 for the hydraulic clutches 42-44 has two neutral positions N7. N2, ■ 1st speed position I where oil is supplied only to the speed hydraulic clutch 42 and operates only the clutch 42, 2nd speed position ■ where oil is supplied only to the 2nd speed hydraulic clutch 43 and only this clutch 43 is actuated, and 3rd speed hydraulic pressure. Supplying oil only to the clutch 44 and operating only the clutch 44 3
A switching valve 59 having five positions including a speed position (3) is provided, and the position of the switching valve 59 is selectively switched by an operating lever 60 to switch the gear stage of the work machine power transmission 18. being done.

In particular, the two operating levers 56 and 68 for switching the gears of the two types of transmissions 17 and 18 described above are releasably interlocked as follows.

That is, the above-described valves 53, 55, 57, and 59 are installed in a valve mechanism housing 61 (FIG. 1) provided on the upper front surface of the mission case 15, together with the oil passages therebetween. 61, the oil passage in the top wall 15a of the mission case 15, the oil passage in the oil passage forming plate 62 on the front surface of the mission case 15, the seal housing 63 that fits over the front end of the transmission shaft 20, and the periphery of the front end of the transmission shaft 20. The hydraulic clutch 32 is connected to the hydraulic clutch 32 through the oil chamber R between the surfaces and the oil passage inside the transmission shaft 20.
-35 to the oil chamber Q, the oil passage in the top wall 15a of the transmission case 15, the oil passage in the support wall member 64 that supports the front end of the PTO shaft 13 and the drive shaft 22, and the front end of the PTO shaft 13. Hydraulic oil is supplied and discharged through the oil chamber R'EL between the seal housing 65 to be fitted and the circumferential surface of the front end of the PTO shaft 13 and the oil chamber Qpe of the hydraulic clutches 42-44 through the 3 internal passages in the PTO shaft 1, respectively. The operation levers 56, 60 are
As shown in the figure, the valve mechanism housing 61 is provided to protrude upward, and as shown in FIG.
6, to which a shift fork 67 for slidingly displacing the spool 55a of the switching valve 55 is fixed, and a rotation shaft 68 that is rotated about the axis by the operating lever 60.
The rotating shaft 68 to which the shift fork 69 for slidingly displacing the spool 59a of the switching valve 59 is fixed is provided on the same axis as the rotating shaft 66, and there is a space between the rotating shafts 66 and 68. A dog clutch C is interposed between a fixed tooth C1 fixed on the rotary shaft 68 and a movable tooth C2 slidably but not relatively rotatable on the rotary shaft 66.
By displacing the movable meshing piece C2 with the engaging/disengaging lever 70, the meshing clutch C rotates both rotation shafts 66 and 68.
Therefore, the operation levers 56 and 60 can be selectively interlocked and connected.

The operating levers 56, 60 and the engaging/disengaging operating lever 70 described above are supported halfway by a lever guide 71 as shown in FIG.

That is, the lever guide T1 has a first forward speed position F1, a second forward speed position F2, and a third forward speed position F3 in one direction from the neutral position N, and a reverse position R in the other direction.
Guide groove 72 for operating lever 56 and negative neutral position N1
1st gear position ■, 2nd gear' position ■ and 3rd gear position ■ in one direction, and another neutral position N2 in the other direction,
An engagement/disengagement mechanism having a guide groove 73 for the operation lever 60, an interlocking operation position As located between both of these id grooves 72 and 73, in which the dog clutch C is inserted, and an independent operation position IN, in which the clutch C is disengaged. A guide groove 74 of the operating lever guide is formed respectively.

In FIG. 2, 75.75' indicates a friction brake plate 76.76' which is slidably but not relatively rotatable on the shaft 20°13, and the friction brake plates 76, 76' are moved. The compression springs 77, 77' are pressed into engagement with the stepped portions of the seal housings 63, 65, and the compression springs 77, 77' are compressed by hydraulic action on the oil chambers 78, 78' to achieve the above-mentioned suppression. The brake is equipped with pistons 79 and 79' that release the travel power transmission 17 and the work machine power transmission 1.
8, the transmission shaft 20 and the PTO shaft 13 are braked by the action of the springs 77 and 77', and a slight engagement force between the friction plates 46 and 47 and between 46' and 47' is used to brake the transmission shaft 20 and the PTO shaft 13.
13 is interlocked and connected to the shaft 19.22 in the preceding stage to prevent it from rotating.

Since the transmission shown in FIGS. 1-5 according to the present invention is constructed as described above, the following smooth operation can be achieved.

In other words, when fertilizing or sowing is carried out using the work implement 6, if the running speed of the tractor is set as the speed, unless the driving speed of the work implement 6 is set as the speed accordingly, the application of fertilizer or seeding will be constant at a predetermined rate. Although seeding is not performed, in the illustrated tractor, the gear ratios between each gear of the traveling power transmission 17 and each gear of the work machine power transmission 18 are set as shown in equation (1) above. Then, the gears of both transmissions 1B are made to correspond, that is, if the gear of the traveling power transmission 17 is set to 1st forward speed, the gear of the work equipment power transmission 18 is set to 1st, etc. The traveling speed of the working machine 6 and the driving speed of the working machine 6 are always kept at a constant ratio, so that no matter how the running speed is changed, sowing or fertilization is always performed at the same ratio.

Moreover, when the engagement/disengagement operation lever 70 is placed in the interlocking operation position As, the operation lever 56 of both transmissions 17, 18
Both transmissions 17 and 18 can be operated by operating one of the operating levers 56 or 60.
The gears are shifted to a common gear stage at the same time, making the operation extremely easy and preventing operational errors.

If, for some reason, it becomes necessary to operate each transmission 17, 1B independently, the interlocking connection between the two operating levers 56, 60 can be cut off by moving the engagement/disengaging operation lever 70 to the independent operation position IN. This independent operation can be performed.

In agricultural tractors, two sets of traveling power transmissions are generally installed in series, but in this case, the gear ratio of each gear of the transmission that is mainly operated during work and the working power The gear ratio of each gear stage of the transmission may have the above relationship.

To explain this with a specific example, in FIG. 6, the following mechanical running power transmission 80, that is, the transmission shaft 20 is disposed downstream of the same hydraulic clutch type running power transmission 17 as described above. and another transmission shaft 81 located on an extension line thereof, the transmission device 80 includes a series of transmission gears 82, 83, 84, 85 loosely fitted to the extension of the drive shaft 19. A speed change gear 82-85, which is interlocked with the gear 82-85 and is inputted from the transmission shaft 20 by meshing an idle gear 86 on the intermediate shaft 19 with a gear 87 at the end of the transmission shaft 20, and a transmission shaft. 3 shift gears 8 on 81
B, 89, 90 and the fixed engagement piece 91a at the end of the transmission shaft 20
and a meshing clutch 91 which is constituted by a movable meshing piece 91b on the side surface of the shift gear 90 and is interposed between the transmission shafts 20 and 81. By displacing the gears, the meshing between gears 82 and 88 provides 1st speed, the meshing between gears 83 and 88 provides 2nd speed, the meshing between gears 84 and 89 provides 3rd speed, and gear 85.
A transmission mechanism for an agricultural tractor is shown, which is equipped with a mechanical traveling power transmission device 80 configured to obtain 4th speed through the meshing of gears 90 and 5th speed through the operation of a dog clutch 91 on a transmission shaft 81. has been done.

Also in FIG. 6, the gear ratio i of each gear of the hydraulic clutch type traveling power transmission 17 and the gear ratio i' of each gear of the work machine power transmission 18 are expressed by equation (1). The relationship is set to

In this case, first, the gear of the mechanical traveling power transmission 80 is set appropriately according to the field conditions, etc., and during work, only the gear of the hydraulic clutch type traveling power transmission 17 is set. They are used by appropriately switching between them, so that the same effect as described above can be achieved.

In FIG. 6, 91 is the main clutch, 92 is a differential device which is inputted from the transmission shaft 81 via a bevel gear 93 and 94 transmission mechanism, 92a is its differential lock device, and 95 is the left and right output shaft of the differential device 92, and each A gear reduction transmission mechanism 96 between the rear wheel axles 2a is a brake for each rear wheel 2 provided on each output end shaft of the differential device 92.

Next, the embodiment shown in FIGS. 7 and 8 will be described. In this embodiment, the running power transmission 17A corresponding to the running power transmission 17 is 1. Forward 1st speed, Forward 2nd speed and Forward 3rd speed
Only three corresponding hydraulic clutches 32, 33, and 34 are provided, and only the speed and forward speed changes are controlled.
Switching between forward and backward movement of the tractor is performed by a forward/reverse movement switching section (not shown), and the working machine power transmission device 18 is constructed in the same manner as described above.

A common hydraulic circuit for both transmissions 17A and 1B including a hydraulic pump 97 and a pressure regulating valve 9B is provided, a common switching valve 99 is inserted into this, and the common switching valve 99 is guided by a lever guide 101 provided with a guide groove 100. Switching valve 9 with operation lever 102
9, and in the neutral position N, both transmissions 17A, 1
B is deactivated, the F1 hydraulic clutch 32 and the first speed hydraulic clutch 42 are activated at the first speed position F11, and the F1 hydraulic clutch 32 and the first speed hydraulic clutch 42 are activated at the second speed position F11.
In 21f, F2 hydraulic clutch 33 and 2nd speed hydraulic clutch 4
In the third speed position F3111, the F3 hydraulic clutch 34 and the third speed hydraulic clutch 44 are activated, and the structure of the hydraulic circuit and operating mechanism is extremely simplified.

In the embodiments described above, both the traveling power transmission device 17 or 17A and the work machine power transmission device 18 are configured as hydraulic clutch type transmission devices, but in the case where both or either one is configured as a mechanical transmission device. Similarly, the transmission device according to the present invention can be made into a transmission device according to the present invention. Next, as a specific example, the traveling power transmission device is a hydraulic clutch type transmission device, the working machine power transmission device is a mechanical transmission device, The respective configurations will be explained with reference to FIGS. 9-16.

As shown in FIG. 9, the traveling power transmission 1T in this embodiment is configured as a hydraulic clutch type transmission completely similar to that described above, but the working machine power transmission 103 is fitted onto the drive shaft 22. three shift gears 104, 105, and 106 with different diameters, and three shift gears 107, 108, and 109 that are movable upwardly on one PTO shaft but are not relatively rotatable. The shift gears 107, 108, and 109 are selectively displaced in three directions on one axis of the PTO shaft, and the meshing between the gears 104 and 107 provides the first speed, and the meshing between the gears 105 and 108 provides the second speed. speed, gear 106
．． This is a mechanical or gear-type transmission device in which three speeds are obtained by meshing between the PTO shafts 13 and 109, respectively.

As in the case described above, the gear ratio of each gear of the traveling power transmission 17 and the gear ratio of each gear of the work equipment power transmission 103 are each set to a constant ratio according to the present invention. .

The traveling power transmission device 17 and the work machine power transmission device 103 described above are operated to change speed by the following speed change operation mechanism.

That is, in FIGS. 10-12, 110 is a shift fork that displaces and operates a switching valve that switches the supply and discharge of hydraulic oil to hydraulic clutches 32-35 in the traveling power transmission 17, and 111 and 112 are work machine power Transmission device 103
This is a shift fork that displaces the shift gears 107°, 108, and 109, but both gears have a loading capacity of 17,103
The shift forks 110, 111, and 112 are operated by a common operating lever 113 as described below.

That is, as shown in FIGS. 10-12, the vehicle machine frame F has a rotation shaft 114 interlockingly connected to shift forks 111 and 112, and a collar 1 on a support shaft 115 protruding from the machine frame F.
16 and interlockingly connected to the shift fork 110 are supported along the transverse direction of the machine frame F so as to be rotatable about their respective axes, and the operating lever 113 directly selectively rotates the rotating shaft 114 and rotating barrel 117 that are parallel to each other, thereby selectively displacing the shift forks 111, 112 and shift fork 110. The operating lever 113, the rotating shaft 114, and the rotating barrel 117 are related to each other as follows in the illustrated case.

That is, a crank arm 118 is fixed to one end of the rotating shaft 114 by appropriate means such as welding, and a rotating cylinder is attached to the other end of the crank arm 118 via a support shaft 119 and a collar 120. 121 is the rotation axis 114
The rotary cylinder 121 is rotatably supported along the direction orthogonal to the rotary cylinder 117.
A rotation operation piece 1 which is a rotation operation piece 122 located on the same axis X as 14 and whose tip portion is formed into a spherical part 122a
22 and a connecting rod 123 which is welded and fixed to the lower end of the operating lever 113 are respectively welded and fixed. , the axis of the operation lever 113 is orthogonal to the common axis X, and the rotation axis 114
The rotating axis of the operating lever 113 in the direction orthogonal to the rotating cylinder 117, that is, in the direction of the arrow A, is designed to coincide with the common axis X mentioned above.

Further, the fork 124 is attached to the rotating shaft 114 and the rotating barrel 117 by welding and fixing the base end to the rotating barrel 117.
The fork 124 is extended along the direction perpendicular to the fork 124, and the fork 124 is made to extend along the direction perpendicular to the fork 124.
A rotation operation piece 122 is held between the two.

As shown in FIG. 10, the rotating shaft 114 is connected to the shifter, which is the operation section of the work machine power transmission 103, via a swinging arm 125, a forward/backward rod 126, a swinging arm 121, a rotating cylinder 128, etc. The rotating cylinder 117 is connected to the forks 111 and 112 in an interlocking manner, and the rotating cylinder 117 is connected to the shifter, which is the operating section of the traveling power transmission 17, via a swinging arm 129, a forward/backward rod 130, a swinging arm 131, a rotating shaft 132, etc. It is interlocked and connected to the fork 110.

Therefore, when the operating lever 113 is rotated in the direction of arrow A, the operating lever 113 is connected to the connecting rod 12.
3 axis, and therefore the above-mentioned common axis X, the rotation shaft 114 is caused to rotate about the axis X through the crank arm 118, and thereby the above-mentioned interlocking mechanism 125-128 The shift forks 111 and 112 are displaced as required to perform a gear change operation of the work machine power transmission device 103. At this time, the rotation shaft 114 and its axis X are common. Since the rotating operating piece 122 rotates about its axis X, it does not exert any displacement action on the rotating cylinder 117.

Conversely, when operating the operating lever 113 in the direction of the arrow B, the operating lever 113 rotates together with the rotary cylinder 121 around the axis Y of the support shaft 119.
At this time, since the rotation operation piece 122 is similarly rotated around the axis Y, the rotation cylinder 117 is rotated around the axis via the fork 124, and therefore the interlocking mechanism 129-132 The shift fork 110 is displaced as required to perform a gear change/disconnect operation of the traveling power transmission device 17.
At this time, since the crank arm 118 is not displaced at all by the rotation of the rotary cylinder 121 about the axis Y, the rotation shaft 114 is not rotated at all.

The common operation lever 113 described above is supported and guided by a lever guide 140 as described below.

That is, as shown in FIGS. 13-16, this lever guide 140 has a guide groove 14 along the direction of the arrow A.
1, and the guide groove 141 is provided at a position such that when the lever 113 is located in the groove 141, the traveling power transmission 17 is held in a neutral state;
a plurality of guide grooves 1 along the direction of the arrow B, intersecting with
42A, 142B, 142C, and 142D, which are the forward first speed position F1 and the forward second speed position F2 of the traveling power transmission 17.
, guide grooves 142A, 142 having third forward speed position F3.
B, 142C and a guide groove 142D having a reverse position R of the traveling power transmission 17, and a guide plate 143 shown in FIG. Position F2. F3 and the third forward speed position F3 of the guide groove 142B.The shielding plate 144 is shown in FIG. A hinge 145 is connected to a guide plate 143 so as to be rotatable between a shielding position shown in the drawing and a non-shielding position shown in chain lines.
In addition, the guide groove 141 and the guide groove 142 of the guide plate 143
A, 142B.

The intersection with 142C is the work machine power transmission device 1.
03's 1st speed position 1, 2nd speed position ``, 3rd speed position ■''.

As described above, when the shielding plate 144 is in the shielding position, the innermost part of the guide groove 142A is located in the transmission gear 17.
is the first forward speed, and the first speed position of the transmission 103 is F, I.
The innermost part of the guide groove 142B is the second forward speed at the shift position 17,
The transmission 103 is in the second gear position F2■, and the guide groove 14
The deepest part of 2C is the third forward speed of the transmission 17, and the transmission 10
3, the innermost part of the guide groove 142D becomes the reverse position R under the neutral state of the transmission 103, and the traveling speed of the tractor and the driving speed of the work implement 6 are made proportional. The speed change operation of both transmission devices 17 and 103 can be performed easily.

If it becomes necessary to operate each transmission 17, 103 independently for some reason, by rotating the shielding plate 144 to its non-shielding position, the above-mentioned This allows for independent operation of

The shielding plate 144 can be supported not only by vertically movable support as described above but also by horizontally rotatable support or slidable support.

Although it has been explained in detail above, in short, the transmission device for the agricultural tractor of the present invention has the following characteristics: An operation lever (1st to 5th
In the illustrated embodiment, the operating lever 56 or the operating lever 60;
In the embodiment shown in FIGS. 7 and 8, the operating lever 102 and the 9-16
In the illustrated embodiment, an operating lever 113) is provided, and as mentioned above, no matter how the traveling speed of the tractor is changed by changing the gear position of the traveling power transmission, the speed is proportional to the traveling speed. When the work machine is driven and the work machine is a seeding machine, fertilizer, or pest control machine, seeding, fertilization, or chemical spraying is always performed at a predetermined constant rate, and the work machine power button - In the case of a tiller such as a tally type, the tilling pitch is always constant and the size of the soil clod to be tilled is constant, and the remarkable advantages are that a constant working condition can always be obtained regardless of the vehicle speed of the agricultural tractor. Moreover, since the operating lever described above can be used to switch between the traveling power transmission and the work equipment power transmission in common to each corresponding gear, this method of gear shifting exhibits the above-mentioned advantages. It has excellent advantages such as being extremely easy to operate and eliminating erroneous operations.

[Brief explanation of drawings]

Fig. 1 is a side view of an agricultural tractor equipped with an embodiment of the present invention, Fig. 2 is a partially cut-away vertical side view of the main parts thereof, and Fig. 3 is a circuit diagram showing the hydraulic circuit of the same embodiment. Fig. 4 is a longitudinal sectional view of the main part of the same embodiment, Fig. 5 is a plan view of the main parts of the same embodiment, Fig. 6 is a diagram of a transmission mechanism of a modified example, and Fig. 7 is a mechanism of another embodiment. Fig. 8 is a plan view of the main parts of another embodiment, Fig. 9 is a partially cutaway longitudinal sectional side view similar to Fig. 2, and Fig. 10 shows another embodiment. 11 is a longitudinal cross-sectional view showing one mechanism in another embodiment, and FIG. 11 is a cross-sectional view of the same mechanism.
12 is a sectional view taken along the line ■-■ in FIG. 11, FIG. 13 is a plan view of the main parts of the same embodiment, FIG. 14 is a side view of the same member, and FIGS. 15 and 16. Each figure is a plan view of two parts constituting the same member. 13...PTO axis, 17...Traveling power transmission, 18...1 work equipment power transmission, 19
...... Drive shaft, 20... Transmission shaft, 22.
... Drive shaft, 23 ... F1 speed change gear, 2
4...F2 speed change gear, 25...F3 speed change gear, 2T...F1 idle gear, 28...
...F2 idler gear, 29...F3 idler gear, 3
2, 33, 34... Hydraulic clutch, 36...
...1st speed gear, 37...2nd speed gear,
38...3rd speed gear, 39...1st speed idler gear, 40...2nd speed idler gear, 41...
...3rd speed idle gear, 42, 43, 44...hydraulic clutch, 55...switching valve, 56...
・Operation lever, 59...Switching valve, 60...
...Operation lever, 66...Rotation shaft, 6T...
...Shift fork, 68...Rotation shaft, 69
...Shift fork, C... Dog clutch, 70... Engagement/disengagement operation lever, 71...
...Lever guide, 17A...Travel power transmission, 99...Switching valve. 101... Lever guide, 102...
Operation lever, 103... Working machine power transmission device,
104,105゜106... Speed gear, 107
,108,109...Shift gear, 110...
...Shift fork, 111°112...
Shift fork, 113... Operation lever, 14
0... Lever guide.

Claims (1)

[Scope of Claims] 1. The gear ratio of each gear of the traveling power transmission and the gear ratio of each gear of the work equipment power transmission are set to a substantially constant ratio, and both transmissions are Transmission device 2 for an agricultural tractor, characterized in that an operating lever is provided for commonly switching the corresponding gears in the gear ratio. Transmission device 3 for an agricultural tractor according to claim 1, characterized in that a lever is provided, wherein one of the transmission levers for independently operating the transmissions is also used as the operation lever. The transmission device for an agricultural tractor according to claim 2, characterized in that: