JPH0735777Y2 - Transmission structure of tractor - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a transmission structure of a tractor, in particular, a front housing and a case of a tractor body, which are connected to each other in the front-rear direction and are driven by an engine. The auxiliary transmission that shifts between the gear and the shift shaft is installed in the rear half of the front housing, while the main transmission that transmits the shift between the drive shaft driven by the shift shaft and the driven shaft is installed. It concerns the transmission structure installed in the first half of the case.

[Conventional technology]

In the front housing of the tractor, the front end of the tractor has an extra space in the latter half where the engine flywheel and main clutch are installed, so that the vehicle speed can be finely adjusted to suit various work applications. In many cases, an auxiliary transmission is installed in the section, and in that case, the above-described transmission structure is generally adopted.

In such a transmission structure, the transmission in the transmission case is shared by the tractors of various specifications, and only the transmission in the front housing can be easily replaced. As a typical example of the conventional technique for facilitating disassembly and reassembly after the fact, there is a technique disclosed in Japanese Patent Publication No. 63-39449.

In this conventional example, the front housing is formed to have a rear end opened and an intermediate wall on the front end side of the auxiliary transmission. Further, the mesh case is divided into front and rear parts to form the front mesh case having an intermediate wall on the front end side and a back wall on the rear end side of the main transmission. A bearing plate (referred to as "mounting wall" in the above-mentioned publication) which is located in the front side transmission case and is attached to the rear end of the front housing is provided, and the driving shaft and the transmission shaft of the auxiliary transmission are provided. Are supported by the intermediate shaft of the front housing and the bearing plate. Further, the drive shaft and the driven shaft of the main transmission are supported by the above-mentioned intermediate wall and back wall of the front side transmission case. The shift shaft of the auxiliary transmission and the drive shaft of the main transmission are connected to each other in the front mesh case on the front side of the intermediate wall of the case.

[Problems to be solved by the invention]

In the above-mentioned prior art, a driving shaft in which the front end side is supported by the intermediate wall of the front housing in a state where the front housing and the front side transmission case are separated and the bearing plate is removed from the rear end of the front housing. And a speed change transmission member such as a gear for an auxiliary speed change device is assembled on the speed change shaft, and then a bearing plate is attached to the rear end of the front housing to support the drive shaft and the rear end side of the speed change shaft. Since it is assembled by connecting the front housing and the front side transmission case while connecting the main transmission and the drive shaft of the main transmission, it is certainly easy to assemble the auxiliary transmission and to disassemble and reassemble the auxiliary transmission. But,
On the contrary, it has the following problems since it is only concerned with the assembly of the auxiliary transmission.

That is, first, the space on the front side of the intermediate wall of the front side transmission case is used as a space for installing the bearing plate and a space for connecting the transmission shaft of the auxiliary transmission and the drive shaft of the main transmission,
Since the main transmission is installed between the intermediate wall and the back wall of the front side mission case by supporting the drive shaft and the driven shaft on these walls, the assembly of the main transmission is extremely difficult. ing. That is, in order to install the main transmission between the intermediate wall and the back wall whose positions are fixed, an opening for installing a speed change transmission member such as a gear is installed between the two walls on the top wall or the side wall of the front side transmission case. The drive transmission shaft and the driven shaft of the main transmission are inserted through the intermediate wall or the rear wall as described above, and the transmission transmission member is installed in the front side transmission case through the opening and held at a predetermined position. While assembling it between the both walls while supporting it, such an assembly is extremely troublesome. For that reason, it is assumed that the rear end of the front side mission case with the front end opened is also opened, and that a separate bearing plate in place of the rear wall is attached to the rear end of the front side case. Since the front mesh case has only the middle wall and the front and back are open, there is a problem in strength and it is difficult to adopt.

In addition, if the tractor specification is a transmission structure that does not have an auxiliary transmission in the front housing while sharing the transmission in the transmission case, the space on the front side of the intermediate wall of the front side transmission case is simply connected to the shaft. It will be used as a space only for the purpose, and a large amount of extra space will be left on the side of the case.

Therefore, this invention simplifies the assembling of not only the auxiliary transmission installed in the front housing but also the main transmission installed in the mesh case and does not create an extra space on the mesh case side. , Is intended to provide a new transmission structure for tractors.

Further, in the present invention, when the auxiliary transmission is a hydraulic clutch type in which the shift speed can be changed lightly by operating a valve, the clutch drive hydraulic mechanism utilizing the driving shaft of the auxiliary transmission and the bearing structure of the transmission shaft. One of the problems is that the above can be incorporated in the front housing together with the auxiliary transmission, and that the simple assembly can contribute to the main idea of the invention.

[Means for solving problems]

Therefore, in this invention, in the transmission structure of the tractor as described above, the mission case 2 is formed so that the front end is opened and the intermediate wall 2a is provided on the rear end side of the main transmission 9. The drive shaft 7 and the driven shaft 8 of the main transmission 9 are supported by the rear bearing plate 10 mounted on the front end of the second transmission 2 and the intermediate wall 2a, and the front housing 1 is opened at the rear end and the auxiliary transmission 6 is provided. Is formed to have an intermediate wall 1a on the front end side thereof, and the drive shaft 4 and the speed change shaft 5 of the auxiliary transmission 6 are attached to the intermediate wall 1a and the front bearing plate 11 mounted on the front surface of the rear bearing plate 10. An intermediate shaft 17 that is supported and that is transmitted from the speed change shaft 5 to the drive shaft 7 is provided so as to be supported by both the bearing plates 10 and 11 described above.

Further, the present invention is configured such that the auxiliary transmission 6 is a hydraulic clutch type in which a plurality of hydraulic clutches 12 and 13 are provided on the transmission shaft 5, and the switching valve device 14 for the auxiliary transmission 6 is the front bearing. Installed on the upper surface of the plate 11, the front bearing plate
11 is provided with an oil passage inheriting cylinder portion 11a for communicating the oil passages 15 and 16 for the hydraulic clutches 12 and 13 formed in the speed change shaft 5 with the oil passages on the fixed position side, and the switching valve device 14 The oil passages 18 and 19 guided from the oil passage inheriting tubular portion 11a to
It is also proposed to form between 10 and 11.

[Function and effect of device]

The transmission structure according to this invention can be assembled as follows.

That is, as for the main transmission 9, first, as can be clearly understood from FIGS. 1 and 2, the front housing 1 and the case 2 are separated from each other, and the rear bearing plate 10 is provided at the front end of the case 2. In a state where the drive shaft 7 and the driven shaft 8 are not mounted, the rear end portions of the drive shaft 7 and the driven shaft 8 are supported on the intermediate wall 2a of the mesh case 2 and gear transmissions such as gears are sequentially mounted on these shafts 7 and 8. Assemble through the openings in the front and back of the case 2. Then, the rear bearing plate 10 on which the front bearing plate 11 is previously mounted on the front surface or the rear bearing plate 10 alone is mounted on the front end of the mesh case 2, and the drive shaft 7 is attached to the rear bearing plate 10. Also, the front end of the driven shaft 8 may be supported.

Next, as can be clearly understood from FIGS. 1, 2 and 6, the auxiliary transmission 6 is mounted on the front surface of the rear bearing plate 10 while supporting the intermediate shaft 17 on both bearing plates 10 and 11. The drive shaft 4 and the speed change shaft 5 are supported by the front bearing plate 10, and the drive shaft 4
And a speed change transmission member such as a gear is sequentially installed on the speed change shaft 5 from the front end side thereof, and the auxiliary speed change device 6 is provided outside the front housing 1.
Will be assembled. On top of that front housing 1
Is connected to the front of the case 2 to connect the drive shaft 4
And the front end side portion of the transmission shaft 5 is an intermediate wall of the front housing 1.
Support 1a.

As described above, the transmission structure of the present invention is such that the main transmission device 9 has the front end of the transmission case 9 under the condition that the drive shaft 7 and the driven shaft 8 are cantilevered by the intermediate wall 2a of the transmission case 2. Assembling can be performed by incorporating a speed change transmission member from the opening, and in the auxiliary speed change device 6, the drive shaft 4 and the speed change shaft 5 are separated from each other by the front side bearing plate 11 supported by the mesh case 2 via the rear side bearing plate 10. Since it is configured to be assembled by assembling the speed change transmission member outside the front housing 1 under the condition that it is held and supported, both the main and auxiliary speed change devices 9 and 6 can be easily assembled. I will.

Further, according to the present invention, the rear bearing plate 10 mounted on the front end of the movement case 2 and the front bearing plate 11 mounted on the front face thereof.
Since the and are located in the front housing 1, the main transmission 9 can be arranged in the front half of the transmission case 1 from directly behind the rear bearing plate 10, and as shown in FIG. When the front housing 1A having the wall 1b is used and the transmission structure is such that the auxiliary transmission is not provided in the housing 1A,
Even if the mission case 2 having the same specifications as the transmission structure according to the present invention is used, no extra space is created in the mission case 2. Therefore, since the main transmission mechanism of the tractor is built in itself and it is manufactured to be sturdy for the same installation, the weight of the mission case 2 becomes large and the front and rear length of the mission case 2 may be short. Since the length and weight of the case case 2 are reduced, the case can be easily handled during assembly, and the weight of the tractor can be reduced.

According to the structure of claim 2, the switching valve device 14 of the clutch hydraulic mechanism for the auxiliary transmission 6 of the hydraulic clutch type, and the oil passages 15 and 16 in the rotating transmission shaft 5 are fixed in position. The oil passage inheritance cylinder portion 11a forming the oil passage rotary joint portion for connecting to the oil passage, and the oil passages 18 and 19 between the switching valve device 14 and the oil passage inheritance cylinder portion 11a, the front bearing plate 11 and the rear side. Bearing plate 10
Since the auxiliary transmission 6 can be incorporated into the front housing 1 in a state where it is integrally equipped with the bearing structure, a hydraulic clutch type auxiliary that can easily shift gears by valve operation. The advantage is that the transmission 6 can be easily assembled and assembled together with the main part of the clutch hydraulic mechanism.

Further, since the oil passage inheriting tubular portion 11a is integrally provided on the front bearing plate 11, and the oil passages 18 and 19 are formed between both bearing plates 10 and 11, it is simple and compact without using an extra member. By providing the switching valve device 14 on the upper surface of the front bearing plate 11 and arranging the switching valve device 14 in the front housing 1, the number of members traveling to the outside of the tractor body is reduced accordingly, and the tractor is reduced. Placement restrictions on members placed on the outer surface of the machine body are relaxed.

〔Example〕

FIG. 1-5 shows the first embodiment. As shown in FIG. 2, the body of the tractor equipped with this embodiment is completed by further connecting a rear housing 20 to the rear of the mission case 2. The case 2 has a back wall 2b,
Further, the rear housing 20 has a pair of front and rear support walls 20a and 20b which are raised from the inner bottom surface. The rear end opening of the rear housing 20 is closed by a rear lid 21.

Similarly, as shown in FIG. 2, the engine 3 is arranged at the frontmost part of the machine body, and is connected to a flywheel 22 arranged at the front end of the front housing 1. The drive shaft 4 is directly connected to the flywheel 22 and is used as a drive shaft for a traveling system and a PTO system.

In addition to the auxiliary transmission 6 and the main transmission 9 described above, the traveling system transmission includes the intermediate wall of the transmission case 2.
Transmission shaft 23 and propeller shaft 24 supported by 2a and back wall 2b
An auxiliary transmission device 25 is provided between them. The propeller shaft 24 is connected to the rear end of the rear shaft 20 and is supported by the supporting wall portion 20a of the rear housing 20.
Output transmission to 6. A power take-out mechanism 27 for taking out front wheel drive force from the propeller shaft 24 is also provided, and this mechanism 27 includes a front wheel drive clutch 28.

A PTO shaft 29, which is supported by the supporting wall portion 20b of the rear housing 20 and the rear lid 21 and extends rearward from the housing 20, is provided, and the PTO transmission transmitted to the PTO shaft 29 is as follows. It is supposed to be like. That is, the intermediate shaft 17, the drive shaft 7, and the transmission shaft 23 of the traveling system are concentrically arranged in the front and rear in this order, and are formed as the intermediate shafts. The drive shaft 31 of the PTO system that penetrates these shafts 17, 7, 23 is connected to the drive shaft 4 at the front end, and the rear end is connected to the rear housing.
It is provided to extend within 20. A hydraulic pump 32 having the drive shaft 31 as a pump shaft and a PTO clutch 34 which is a hydraulic clutch arranged between the drive shaft 31 and a clutch shaft 33 on an extension line thereof are arranged above the front end of the rear housing 20. The PTO clutch 34 is additionally provided with a brake 35 for eliminating inertial rotation on the driven side of the clutch. The clutch shaft 33 is linked to the front and rear transmission shafts 36 and 37 on the extension line thereof, and the PTO transmission 39 is arranged between the rear transmission shaft 37 and the hollow transmission shaft 38 loosely fitted on the PTO shaft 29. Has been done. Also, the grand PTO transmission shaft 40, which is driven to rotate by the propeller shaft 24.
Is installed in the lower part of the rear housing 20.
40 drives a ground PTO gear 41 which is loosely fitted to the PTO shaft 29. PT
Between the transmission shaft 38 on the O-axis 29 and the ground PTO gear 41, a live PTO that can be selectively coupled to the PTO shaft 29.
・ Grand PTO and switching clutch 42 are installed.

As shown in FIGS. 1 and 3 and 4, the rear bearing plate 10 is
It is formed to have a size slightly smaller than the opening size of the front housing 1 and the mesh case 2, and is connected to the connecting portion 2c projecting on the inner surface of the mesh case 2 by the bolts 44 on the front side. It is supposed to be attached to the front end of the mission case 2. The front bearing plate 11 is formed to have a smaller size than the rear bearing plate 10.
It is supposed to be mounted on the front surface of the rear bearing plate 10 by means of bolts 45 that are inserted through the bolt insertion holes 10a formed in 10 into the screw holes 11b of the front bearing plate 11 and screwed from the rear side. Therefore, the front bearing plate 11 in the example
Is mounted on the rear bearing plate 10 in advance before mounting on the front end of the mesh case 2. Note that FIG. 3 shows a divided state for easy understanding. The front bearing plate 11 is formed with the oil passage inheriting cylinder portion 11a and the shaft supporting cylinder portion 11c projecting forward, and a pedestal portion 11d for mounting the switching valve device 14 is formed on the upper end. I am doing it.

As shown in FIG. 1, the drive shaft 4 is supported at its front end side by the intermediate wall 1a of the front housing 1 via a ball bearing 47. The ball bearing 48, which supports the rear end side of the driving shaft 4, is received by the intermediate shaft 17, whereby the driving shaft 4 is supported.
The rear end side is in a relationship of being supported by the front bearing plate 11 via the intermediate shaft 17. The speed change shaft 5 is supported by the intermediate wall 1a and the front bearing plate 10 via ball bearings 49 and 50, respectively. In addition, the intermediate shaft 17 is the shaft support cylinder portion 11c of the front bearing plate 11.
Are pierced through and are supported by the front and rear bearing plates 11 and 10 via ball bearings 51 and 52, respectively. The drive shaft 7 and the driven shaft 8 arranged in the mesh case 2 are supported by the rear bearing plate 10 and the intermediate wall 2a of the mesh case 2 via ball bearings 53, 54 and 55, 56, respectively. The hollow intermediate shaft 17 and the drive shaft 7 are connected in the rear bearing plate 10 by a spline connection 57, with the intermediate shaft 17 having a larger diameter. The drive shaft 4 and the drive shaft 31 of the PTO system are connected to each other by a coupling 58 inside the intermediate shaft 17.

Similarly, as shown in FIG. 1, the first embodiment is provided with the above-mentioned hydraulic clutch type auxiliary transmission device 6. Two gears 59, 60 are fitted on the drive shaft 4, and the gear 61 and the intermediate wall 1a, which directly mesh with the gear 59, are mounted on the transmission shaft 5.
A gear 62 meshing with the gear 60 is loosely fitted to the gear 60 via an idler gear 63 that is rotatably supported. The hydraulic clutch 12,1
3 is a clutch housing that is fixedly installed on the transmission shaft 6
It is a multi-plate friction type having four gears 61, 62 and a clutch housing 64 in which friction elements addressed to a plurality of sheets are slidably supported. Each hydraulic clutch
12 and 13 supply the hydraulic pressure to the hydraulic chambers 12a and 13a in the clutch housing 64 as usual, and the pistons 12c and 13c are displaced toward the friction element against the force of the return springs 12b and 13b, and the clutch engagement is performed. It is configured to combine. The speed change shaft 5 is connected to the hydraulic chambers 12a, 13a by the oil passage 1
In addition to 5,16, the lubricating oil passages 65A, 65B communicating with the bearing portion on the speed change shaft 5 and the lubricating oil passages 66A, 66B communicating with the friction element portions of the hydraulic clutches 12, 13 are drilled. There is.

An output gear 67 is fitted on the front side of the front bearing plate 11 on the speed change shaft 5, and the output gear 67 meshes with a gear 68 integrally formed on the front end of the intermediate shaft 17 to form an intermediate gear with the speed change shaft 5. The axes 17 are connected.

Similarly, as shown in FIG. 1, the main transmission 9 is of a synchronous mesh type that carries out four shifts.
Gears 69I, 69II, 6 for 1-4 speeds loosely fitted on the drive shaft 7
9III, 69IV and 1st-4th gears 70I, 70II, 70III, 70IV fixedly installed on the driven shaft 8 are meshed with each other to form a pair of front and rear compound synchronous clutches 71A, 71B provided on the drive shaft 7. Therefore, the gears 69I-69IV can be selectively coupled to the drive shaft 7.

In addition, the auxiliary transmission 25 provided in the latter stage of the main transmission 9
As shown in FIG. 2, the gear 72 on the rear end of the driven shaft 8 meshes with the gear 73 on the front end of the transmission shaft 23, and two transmission gear trains are arranged between the transmission shaft 23 and the propeller shaft 24. It is supposed to be installed. The sub-transmission device 25 includes a clutch that allows the driven shaft 8 and the propeller shaft 24 to be directly connected, and performs a total of three speeds. The four clutch shifter shafts 74 for operating the clutches of the main transmission 9 and the sub-transmission 25 are the transmission case 2
They are slidably supported by the back wall 2b, the intermediate wall 2a, and the rear bearing plate 10 along the front-rear direction.

Explaining the hydraulic mechanism for the hydraulic clutches 12 and 13,
An oil conduit 75 led from the hydraulic pump 32 shown in FIG.
Connect the oil passage 76 communicating with the rear bearing plate 1 as shown in Figs.
It is bored at 0 and opened at the front surface of the bearing plate 10. Further, as shown in FIG. 4, the oil passage 1 is provided on the rear surface of the front bearing plate 11.
8,19, oil passage 77 communicating with the oil passage 76 of the rear bearing plate 10
P and the oil passages 77L ₁ and 77L ₂ communicating with the lubricating oil passages 65A, 65B and 66A, 66B in the speed change shaft 5, respectively.
L ₁ and 77L ₂ are formed as grooves extending from the upper end to the lower end of the front bearing plate 11. These oil passages 18,19,77P,
77L ₁ and 77L ₂ are sealed to the outside by mounting the front bearing plate 11 on the front surface of the rear bearing plate 10, and form a completed oil passage between both bearing plates 10 and 11. It is supposed to be.

These oil passages 18, 19, 77P, 77L ₁ and 77L ₂ are on the upper end side thereof, and the pedestal portion 11 of the front bearing plate 11 as shown in FIG.
It communicates with the recessed grooves 78F, 78R, 78P, 78L ₁ and 78L ₂ that are recessed in the upper surface of d. As shown in FIG. 1, the front bearing plate 11
The oil passage inheriting cylinder portion 11a has a hole penetrating forward and backward, and the inner peripheral surface thereof supports the rear end portion of the speed change shaft 5, but the outer peripheral surface of the rear end portion of the speed change shaft 5 is supported. The three annular recessed grooves formed and the recessed groove formed in the front surface of the rear bearing plate 10 allow the oil distribution chambers 79F and 7F to communicate with the oil passages 15 and 16 inside the speed change shaft 5, respectively.
9R and oil distribution chambers 79L ₁ and 79L ₂ communicating with the lubricating oil passages 65A, 65B and 66A, 66B in the speed change shaft 5 are formed.
The oil passages 18, 19, 77L ₁ and 77L ₂ shown in FIG. 4 are in communication with the oil distribution chambers 79F, 79R, 79L ₁ and 79L ₂ at their lower ends, respectively.

As shown in FIG. 3, the switching valve device 14 projects from the top surface of the valve case toward the lower end, and is fitted to the pedestal portion 11d by six bolts 14a screwed into the screw holes 80 of the pedestal portion 11d. It is supposed to be worn. In this mounted state, the recessed grooves 78P, 79F, 78R, 78L ₁ and 78L _{2 on the} upper surface of the pedestal portion 11d communicate with the oil passages in the switching valve device 14, respectively. The grooves 78F ₁ and 78F ₂ function as clutch hydraulic oil output ports, and the concave grooves 78L ₁ and 78L ₂ function as lubricating oil output ports.

The internal structure of the switching valve device 14 will be described with reference to the circuit diagram shown in FIG. 5. The switching valve device 14 includes a switching valve 82 that controls the supply and discharge of hydraulic pressure to and from the hydraulic clutches 12 and 13, as well as an oil passage opening and closing. Valve 83
And an inching valve 84, and hydraulic oil is supplied to the primary side of the switching valve 82 via the oil passage opening / closing valve 83 and the inching valve 84. The switching valve 82 is a hydraulic clutch 12.
And a position R for activating the hydraulic clutch 13, and the hydraulic pressure acting on the hydraulic clutches 12, 13 is set by known hydraulic pressure increasing type relief valves 85F, 85R.

A constant ratio shunt valve 86 is provided on the primary side of the oil passage opening / closing valve 83, one of the shunt circuits 86a is guided to the oil passage opening / closing valve 83, and the other shunt circuit 86b is relieved from the relief valves 85F, 85R. The lubricating oil circuit 87 is joined to the circuit 85a and is led to the primary side of the inching valve 84.

The oil passage opening / closing valve 83 blocks the end of the flow dividing circuit 86a, and connects the oil passage closing position I connecting the connection circuit 88 between the opening / closing valve 83 and the inching valve 84 to the oil tank and the two circuits 86a, 88. It has an oil passage open position II and is urged to be displaced toward the oil passage closed position I by a valve spring 83a. A hydraulic operating circuit 89 for applying hydraulic pressure to the oil passage opening / closing valve 83 from the opposite side of the valve spring 83a is introduced from the primary side of the diversion valve 86 to the primary side of the oil passage opening / closing valve 83. When the oil passage opening / closing valve 83 is displaced to the oil passage opening position II, 89 is connected to the hydraulic action circuit 90 on the secondary side of the opening / closing valve 83, and after that, the displacement operation force for the oil passage opening / closing year 83 is released. Even if it is done, the oil passage opening / closing valve 83 is held at the oil passage opening position II by the hydraulic action through the hydraulic action circuits 89, 90.

The inching valve 84 has three positions, a non-decompression position A, a decompression position B, and a hydraulic unload position C. At the non-decompression position A, the connection circuit 88 is directly connected to the connection circuit 91 between the inching valve 84 and the switching valve 82. It is configured to communicate,
The non-depressurized position A is always taken by the urging force of the valve spring 84a. A pedal 92 is provided for displacing the inching valve 84 against the force of the valve spring 84a. In the depressurized position B where the pedaling amount of the pedal 92 is adjusted to reach the inching valve 84, the connection on the primary side is made. A part of the oil that flows in from the circuit 88 is made to flow out to the tank circuit 92 'through the variable orifice 84b, and the hydraulic pressure of the secondary side connection circuit 91 is reduced to a variable degree of pressure reduction, whereby the hydraulic clutch.
It is said that 12 and 13 can be slip-engaged. When the pedal 92 is fully depressed, the inching valve 84 is moved to the hydraulic unload position C, and in this state, the connection circuit on the primary side is connected.
88 is connected to the tank circuit 92 'and the secondary side connection circuit 91 is connected to the oil tank, so that the hydraulic action on the hydraulic clutches 12 and 13 is eliminated and the vehicle is stopped.

The inching valve 84 also includes the bearing portion (referred to as L ₁ in FIG. 5) on the transmission shaft 5 described above with reference to FIG.
Also, the supply of lubricating oil to the friction element portions (indicated by reference numeral L ₂ in FIG. 5) of the hydraulic clutches 12 and 13 is controlled, and from the secondary side of the valve 84, as shown in FIG. Lubricating oil circuits 93L ₁ and 93L ₂ connected to the bearing portion L ₁ and the friction element portion L ₂ are led out through the oil passages 77L ₁ and 77L ₂ and the lubricating oil passages 65A and 65B and 66A and 66B. Inching valve 84
It is communicated with the non-reducing position both lubricating oil circuit of the A to the lubricating oil circuit 87 of the primary side as the secondary side 93L _1, 93L _2, also reducing position B in the lubricating oil circuit 87,93L between ₁ causes it communicated Connects the lubricating oil circuit 87, 93L ₂ via a variable orifice 84c, and at the hydraulic unload position C, the lubricating oil circuit
Although the communication relationship between 87 and 93L _{1 is} maintained, the lubricating oil circuit 93L ₂ is supposed to be connected to the oil tank. That is, in the pressure reducing position B where the hydraulic clutches 12 and 13 are slip-operated and the vehicle is traveling at low speed, the clutch friction element portion L ₂
In order to stop the vehicle by unloading the working hydraulic pressure of the hydraulic clutches 12 and 13, the clutch friction friction is reduced in order to reduce the amount of lubricating oil supplied to the clutch slip operation. Lubricating oil is discharged from the element portion L ₂ to prevent accidental vehicle traveling due to the frictional element being accompanied by the lubricating oil.
The relief valve 94 for setting the oil pressure of the lubricating oil is provided outside the switching valve device 14, and as shown in FIG.
It is installed inside.

As shown in FIG. 1, the top wall of the front housing 1 is provided with an opening for incorporating the operating mechanism for the switching valve device 14 and is covered by a cover 95. The pedal shown in FIG. 92
Vertical operating shaft 9 with arm 96a connected to
6, the cover 95 is rotatably supported by the cover 95. Further, an interlocking plate 97 that is displaceable by an arm 96b attached to the lower end of the operating shaft 96 is provided, and the interlocking plate 97 simultaneously operates the operating rod portion 84d of the inching valve 84 and the push rod 83b for the oil passage opening / closing valve 83. It is supposed to be displaced. Accordingly, the oil passage opening / closing valve 83 is displaced from the oil passage closing position I to the oil passage opening position II by the depression operation of the pedal 92 that moves the inching valve 84 to the pressure reducing position B and the hydraulic pressure unloading position C. . After that, when the pedal 92 is released, the push rod 83b separates from the oil passage opening / closing valve 83, but as described above, the opening / closing valve 83 resists the force of the valve spring 83a by the hydraulic operation via the hydraulic operating circuits 89, 90. Oil passage open position I
Be locked in. When the drive of the hydraulic pump 32 is stopped by the stop of the engine 3 and the hydraulic pressure is not supplied to the switching valve device 4, the oil passage opening / closing valve 83 returns to the oil passage closing position I by the force of the valve spring 83a.

The oil passage opening / closing valve 83 as described above is provided for the purpose of ensuring safety at the time of starting the engine 3. Since the oil passage opening / closing valve 83 is at the oil passage closing position I only by starting the engine 3, The vehicle will not start because the hydraulic pressure is not supplied to the hydraulic clutches 12 and 13. When the inching valve 84 is moved to the hydraulic pressure unload position C by depressing the pedal 92 widely, the oil passage opening / closing valve
83 is moved to the oil passage opening position II, and then the inching valve 84 is gradually released by gradually releasing the pedal 92.
Since the vehicle is returned to the non-depressurized position A after passing through, the vehicle can be started in a safe and safe manner.

As shown in FIG. 2, a cover 99 for closing an opening provided on the top wall of the rear half of the case 2 for incorporating the operation mechanism of the auxiliary transmission 25 is provided with another valve device 10 on its inner surface.
Equipped with 0. And this valve device 100 is the fifth
The structure shown in the figure is a hydraulic circuit.

That is, first, the hydraulic pump 32 is used to supply hydraulic oil to the hydraulic clutches 12 and 13 as well as to supply hydraulic oil to the front wheel drive clutch 28 and the PTO clutch 34 which are also hydraulic clutches. In addition, a shunt valve 101 for diverting the pump discharge oil in the direction of the switching valve device 14 and in the directions of the front wheel drive clutch 28 and the PTO clutch 34 is provided in the valve device 100. The diversion valve 101 is configured to have a constant flow rate type as shown in the drawing, the control flow circuit 101a is connected to the switching valve device 14, and the surplus flow circuit 101b is guided to the front wheel drive clutch 28 and the PTO clutch 34. .

Similarly, as shown in FIG. 5, the surplus flow circuit 101b is connected to the primary side of the electromagnetic switching valve 102 for the front wheel drive clutch 28. At the neutral position N of the electromagnetic switching valve 102, the surplus flow circuit 101b is connected to the oil supply circuit 104 connected to the primary side of the switching valve 103 for the PTO clutch 34 as shown in the figure. A relief valve 105 for setting the hydraulic pressure applied to the front-wheel drive clutch 28 when the electromagnetic switching valve 102 is moved to the operating position D is in a bypass 106 that bypasses the electromagnetic switching valve 102 and connects between the circuits 101 and 104. When the front wheel drive clutch 28 is inserted, the relief oil of the relief valve 105 is supplied to the oil supply circuit 104.

The switching valve 103 is moved from its neutral position N'to the operating position E and P
The hydraulic pressure acting on the clutch 34 when the TO clutch 34 is inserted is set by a relief valve 107 of gradually increasing hydraulic pressure. Further, the brake 35 for preventing inertial rotation on the driven side of the clutch 34 when the PTO clutch 34 is turned off by returning the switching valve 103 to the neutral position N'is of a hydraulically operated type, and as shown in the figure, the switching valve 103 The hydraulic pressure set by the relief valve 108 can be applied at the neutral position N '. The relief oil of the relief valves 107 and 108 is guided to the primary side of the switching valve 103 by the lubricating oil circuit 109. In FIG. 5, L' ₁ and L' ₂ indicate the bearing portion and the friction element portion of the PTO clutch 34 portion, and the lubricating oil is constantly supplied from the lubricating oil circuit 109 to the bearing portion L' ₁ by the circuit 110. There is one thing. In addition, switching valve 10
A circuit 111 for supplying lubricating oil to the friction element portion L ′ ₂ is led out from the secondary side of 3, and this circuit 111 is used for the switching valve 10
By means of 3, it is connected to the lubricating oil circuit 109 on the primary side only at its operating position E. I mean PTO Clutch 3
It is designed to reduce the drag phenomenon of the friction element of the clutch 34 due to the lubricating oil when the clutch 4 is cut, and to reduce the load on the brake 35.

In the first embodiment described above, the inching valve 84 is moved to the hydraulic unload position II so that the transmission of traveling power is cut off by the auxiliary transmission device 6 and the main transmission device 9 or the auxiliary transmission device 25. The transmission can be operated and the PTO clutch 34 can be cut to cut off the conduction of PTO power to the PTO transmission 39.
The main clutch is not provided because the gear shifting operation can be performed and the stopped state of the vehicle can be maintained by locking the pedal 92 to the lowest position. It is needless to say that the hydraulic clutch type auxiliary transmission device 6 can be configured as a device for performing high and low two-speed gear shifting or a device having three or more gear speeds, unlike the example shown in the figure.

FIG. 6 shows a second embodiment in which the auxiliary transmission 6 is mechanical.

In this embodiment, the main clutch 115 and its operating mechanism are installed in the front housing 1 on the front side of the intermediate wall 1a.
Although not shown, the main clutch 115 has a general structure, and the main driving shaft 4A that constantly rotates by the engine can be disconnected from the hollow driving shaft 4 similar to that provided in the first embodiment. Connecting. Also, its operating mechanism is also as usual.
An operation in which a release shifter 117 equipped with a release bearing 117a is slidably supported on a shifter receiving cylinder 116 fixedly supported by the intermediate wall 1a and provided on the outer peripheral side of the driving shaft 4, and rotationally displaced by a clutch pedal (not shown). Attach the release fork 119 engaged with the release shifter 117 to the pipe shaft 118, and depress the clutch pedal to release the release shifter 117.
Is slidably displaced in the forward direction to cut the main clutch 115. The main drive shaft 4A is used as a direct drive shaft for the PTO system, and is coupled to the drive shaft 31 of the PTO system by a coupling 58 similar to the one described above.

Gears 59, 60 and 61, 62, which are substantially the same as those provided in the first embodiment, are installed on the drive shaft 4 and the speed change shaft 5, and the auxiliary transmission 6 selects the gears 61, 62 on the speed change shaft 5. A dual friction plate type synchronous clutch 119 that is mechanically coupled to the speed change shaft 5 is provided on both gears 61,
It is composed of a synchro mesh type installed between 62. The synchronous clutch 119 includes the intermediate wall 1a and the front bearing plate 11
It is operated by a shift rod 120 slidably supported by and a shifter 121 attached thereto. The vertical operating shaft 122, which is rotationally displaced by a gear shift lever (not shown),
It is provided by being supported by a cover 95 similar to the above,
An arm 122a for sliding the shift rod 120 is attached to the inner end of the operation shaft 122. The rod bearing 11e formed to project above the front end of the front bearing plate 11 has a detent ball and a spring not shown in the figure inside, and the annular groove holes 123N, 123F, 123R for the detent into which the ball projects,
It is formed on the peripheral surface of the shift rod 120.

In the second embodiment, the auxiliary transmission 6 for performing two forward and reverse gear shifts can have a smaller front-rear width as compared with the hydraulic clutch type, so that the drive shaft 4 and the transmission shaft 5 are the same as those in the first embodiment. The front bearing plate 11 has a shorter length than that of the case, and the intermediate shaft 17 has a longer length, and the front-rear bearing plate 11 has a larger front-rear width. However, the structure of other parts is substantially the same as that of the first embodiment. Does not change. The structure including the main transmission 9 (not shown) and the parts subsequent to the transmission case 2 are exactly the same as those in the first embodiment.

FIG. 7 shows the structure after the mission case 2 as the main transmission 9.
An example of a tractor having a specification in which the auxiliary transmission is not provided in the front housing 1A is shown in exactly the same manner as in the first and second embodiments except that a reverse gear is added to the. In the structure shown in FIG. 7, in the front housing 1A, on the front side of the intermediate wall 1a, there is provided a main clutch 115 and its operating mechanism which are substantially the same as those described with reference to FIG. The drive shaft 4 of the drive system driven by the engine via the main clutch 115 is
The tube shaft 4a having a large diameter is welded and fixed by the rear end, and is connected to the drive shaft 7 by the spline connection 57 similar to that described above.

As described above, when the mesh case 2 having the structure shown in FIG. 7 is also used for the transmission structure of the present invention, no extra space is generated on the mesh case side.

[Brief description of drawings]

FIG. 1 is a partially developed vertical sectional side view showing an essential part of a tractor equipped with the first embodiment of the present invention, and FIG. 2 is a schematic vertical sectional side view showing the entire transmission mechanism of the tractor, FIG. 3 is an exploded perspective view of an essential part of the first embodiment, FIG. 4 is a longitudinal rear view of an essential part of the first embodiment, FIG. 5 is a hydraulic circuit diagram showing a hydraulic mechanism of the tractor, and FIG. Is a partially developed longitudinal side view showing the essential parts of the tractor equipped with the second embodiment, and FIG. 7 is a tractor essential part when the transmission structure according to the present invention is changed to a specification without an auxiliary transmission. It is a vertical side view of a part. 1 ... front housing, 1a ... intermediate wall, 2 ... miss case, 2a ... intermediate wall, 3 ... engine, 4 ... driving shaft, 5 ... shift shaft, 6 ... auxiliary transmission, 7 ... drive shaft, 8 ... driven shaft, 9 ... main transmission, 10 ... rear bearing plate, 10a ... bolt insertion hole, 11 ... front bearing plate, 11a ...
Oil passage inheritance cylinder part, 11b …… Screw hole, 11c …… Shaft support cylinder part, 11
d …… Pedestal part, 12,13 …… Hydraulic clutch, 14 …… Switching valve device, 15,16 …… Oil passage, 17 …… Intermediate shaft, 18,19 …… Oil passage, 44
…… Bolts, 45 …… Bolts, 59,60 …… Gears, 61,62 ……
Gears, 63 …… idler gears, 67 …… output gears, 68 …… gears, 69I, 69II, 69III, 69IV …… gears, 70I, 70II, 70III, 70
IV …… Gear, 71A, 71B …… Composite synchronous clutch, 79F, 79R, 7
9L ₁ , 79L ₂ …… Oil distribution chamber, 82 …… Switching valve, 119 …… Double-type synchronous clutch.

Claims (2)

[Scope of utility model registration request] Claim: What is claimed is: 1. A front housing 1 and a mesh case 2 which form the body of a tractor are connected in series to the front and rear, and an engine 3 is provided.
The auxiliary transmission device 6 for transmitting the speed change between the drive shaft 4 and the speed change shaft 5 driven by the above is installed in the rear half of the front housing 1, while the drive shaft 7 driven by the speed change shaft 5 and the driven device are driven. In the transmission structure of the tractor, in which the main transmission device 9 that performs speed change transmission with the shaft 8 is installed in the front half of the transmission case 2, the transmission case is opened so that the front end is open and the rear end side of the main transmission device 9 is opened. And a rear bearing plate 10 mounted on the front end of this mesh case 2 and the intermediate wall 2a.
The drive shaft 7 and the driven shaft 8 are supported by 2a, and the front housing 1 is formed so that the rear end is opened and the intermediate wall 1a is provided on the front end side of the auxiliary transmission device 6. 1a
And the front bearing plate 11 mounted on the front surface of the rear bearing plate 10 to support the drive shaft 4 and the speed change shaft 5, and the intermediate shaft 17 transmitted from the speed change shaft 5 to the drive shaft 7 as described above. A transmission structure characterized by being provided so as to be supported by bearing plates (10, 11). 2. The auxiliary transmission 6 is a hydraulic clutch type equipped with a plurality of hydraulic clutches 12 and 13 on the transmission shaft 5, and a switching valve device 14 for the auxiliary transmission 6 is provided on the front side. The front bearing plate 11 is installed on the upper surface of the bearing plate 11.
Is provided with an oil passage inheriting cylinder portion 11a for communicating the oil passages 15 and 16 for the hydraulic clutches 12 and 13 formed in the speed change shaft 5 with the oil passages on the fixed position side. The oil passages 18 and 19 guided into the oil passage inheriting tubular portion 11a are provided with the above-mentioned both bearing plates 1
The transmission structure according to claim 1, wherein the transmission structure is formed between 0 and 11.