KR20040009365A - Transmission for tractor - Google Patents

Abstract

PURPOSE: A transmission of a tractor is provided to optimally keep power transmitting efficiency and make the structure of the transmission compact by optimally arranging various equipments in a transmission case and to easily mount an implement to a mid PTO(Power TakeOff) device by removing obstacles from the front space of the mid PTO device. CONSTITUTION: A transmission of a tractor is composed of a main transmission(10) for receiving power from an engine and performing forward and reverse shifting; a sub transmission(20) for receiving power from the main transmission and performing and transmitting plural gear levels of shifting to rear wheels; a four-wheel drive transmission(70) for selectively transmitting power from the sub transmission to front wheels; an independent PTO clutch(40) for receiving power from the engine, separately from the main transmission, and selectively intermitting the transmission of power; a mid PTO(50) device for selectively receiving power from the independent PTO clutch; and a rear PTO(60) device for selectively receiving power from the PTO clutch.

Description

TRANSMISSION OF TRACTOR {TRANSMISSION FOR TRACTOR}

The present invention relates to a transmission of a tractor, and more particularly to a hydrostatic transmission (hereinafter referred to as HST).

HST is a relative term for hydrodynamic transmission (HDT). HDT is a method of transmitting power by using the low torque and high speed characteristics of a fluid like a torque converter in an automobile. On the other hand, HST is a method of transmitting power at low speed and high torque by using static characteristics of a fluid, and is capable of continuously changing speed without using a clutch.

The HST is divided into two types, the open type and the closed type. The open type is mainly used in construction equipment, and the hydraulic pump and the hydraulic motor are separated from each other. On the other hand, the closed type is a structure in which the hydraulic pump and the hydraulic motor are integrally formed. The hydraulic pump has a swash plate which is operated by receiving power from the engine, which changes the volume of the hydraulic pump according to the engine power. The hydraulic pump is operated by the hydraulic pressure discharged according to the inclination of the swash plate.

The transmission of the tractor having the HST made of the hydraulic pump and the hydraulic motor as described above is mainly made six-speed shift using the HST for forward and backward. In addition to the HST, a sub transmission is provided in the tractor's transmission, which is a mechanical three-speed transmission that the operator operates with a lever. Therefore, the transmission of the tractor is a six-speed, three-speed transmission to the sub-speed transmission of the peripheral gear, which is HST, so that a total of 18 speeds can be shifted. The choice of forward and reverse is made with the peripheral gear. Peripheral gears are shifted back and forth according to the forward and backward direction when the operator pedals.

In addition, since a tractor is a four-wheel drive in most cases, the recent trend is that the tractor is also provided with a four-wheel drive transmission for transmitting power transmitted to the rear wheel from the sub-speed transmission.

On the other hand, unlike a car, the tractor must have a function of operating the work machine as well as the forward and backward movements, and thus, a PTO (Power TakeOff) device is provided for selectively receiving engine power without passing through the peripheral gear device to drive the work machine. Thus, the transmission of the tractor has an independent PTO clutch for selectively transmitting engine power to the PTO device. On the other hand, there may be one PTO device, but in order to enable the tractor to perform various tasks, it may be two. Currently, most tractors have a rear PTO and a mid PTO, whereby a work machine is installed in each PTO so that two tasks can be performed simultaneously or separately.

The transmission having the above configuration is mounted in the transmission case, unlike the car, the case serves as a housing without a separate housing. Therefore, the upper part of the case becomes the bottom of the cabin by which an operator sits and adjusts directly. That is, the part where the worker's foot is placed becomes the upper surface of the case.

As mentioned above, the transmission of the tractor has a very complicated configuration due to the various functions of the tractor. However, the size of the transmission case is limited, and the proper arrangement of transmissions having a complicated configuration inside the limited transmission case while exhibiting optimum power transmission efficiency is the most emerging problem in transmission design.

For example, Japanese company Kuboda has disclosed a structure in which a hydraulic pump and a hydraulic motor are arranged in parallel on the same height. Such a structure has the advantage that the height of the transmission is lowered, while the width is longer.

In addition, the most difficult part for the operator is to mount the work machine on the PTO device, especially the mid-PTO device disposed in the middle, and the conventional transmission structure could not completely solve this problem. More specifically, the front space of the mid PTO output shaft which protruded from the mid PTO apparatus was very narrow, and it was very difficult to attach a work machine to the mid PTO output shaft.

In addition, in the conventional transmission, when the mid PTO device and the rear PTO device are integrally connected, all of the PTOs are inevitably rotated even when the mid PTO or the rear PTO is selectively operated. When you want to operate only one PTO device, if the other PTO device also works together, power loss occurs.

The present invention has been made to solve the above-mentioned problems in the conventional transmission, and an object thereof is to provide a transmission of a tractor efficiently disposed inside a narrow case while maintaining an optimum power transmission efficiency.

Another object of the present invention is to expand the front space of the PTO apparatus, in particular the mid PTO apparatus, so that the work machine can be easily attached to the mid PTO apparatus.

Still another object of the present invention is to prevent power loss by preventing power from being transmitted to the rear PTO device when the mid PTO device is operated by the operator's selection.

1 is a cross-sectional view showing the entire transmission according to the present invention.

FIG. 2 is an enlarged cross-sectional view of the peripheral gear device in the transmission shown in FIG. 1. FIG.

3 is an enlarged cross-sectional view of an auxiliary transmission in the transmission illustrated in FIG. 1.

4 is an enlarged cross-sectional view of a four-wheel drive transmission in the transmission shown in FIG.

5 is an enlarged cross-sectional view of the independent PTO clutch in the transmission shown in FIG.

6 is an enlarged cross-sectional view of the mid PTO device in the transmission shown in FIG. 1;

7 is an enlarged cross-sectional view of the rear PTO device in the transmission shown in FIG. 1;

8A to 8C are cross-sectional views illustrating only the peripheral speed and the sub transmission in the transmission of FIG. 1 to explain the forward and backward shifting operations by the peripheral speed and the sub transmission of the transmission according to the present invention.

8A is a view showing a power transmission path of a sub transmission intermediate speed stage.

8B is a view showing a power transmission path of the sub transmission high speed stage.

Figure 8c is a view showing the power transmission path of the sub transmission low speed stage.

Figure 9 is a cross-sectional view showing the addition of a four-wheel drive transmission to the diagram of Figure 8 to illustrate that power is also transmitted to the front wheels by the four-wheel drive transmission of the transmission according to the present invention.

10 and 11 are cross-sectional views illustrating only the independent PTO clutch, the mid PTO and the rear PTO device in the transmission of FIG. 1 to illustrate that power is transmitted to the mid PTO and the rear PTO device in the transmission according to the present invention.

10 is a cross-sectional view illustrating a state in which power is transmitted only to the mid PTO device and power transmission is blocked to the rear PTO device.

11 is a cross-sectional view showing a state in which power is transmitted only to the rear PTO device and power is cut off to the mid PTO device.

-Explanation of symbols for the main parts of the drawings-

One ; Transmission case 10; Peripheral gear

20; Sub transmission 30; Differential

40; Independent PTO clutch 50; Mid PTO Device

60; Rear PTO device 70; Four-wheel drive

In order to achieve the above object of the present invention, the transmission of the tractor according to the present invention includes a peripheral speed gear that is connected to the peripheral speed input shaft that receives power from the engine to perform a plurality of forward and reverse shifts. The output shaft of the peripheral speed gear is disposed below the peripheral speed input shaft, and the auxiliary transmission is connected to the peripheral speed output shaft. The auxiliary transmission device includes an auxiliary transmission input shaft connected to the peripheral speed output shaft and an auxiliary transmission output shaft disposed above the auxiliary transmission input shaft. The auxiliary transmission output shaft is disposed above the auxiliary transmission input shaft. A four-wheel drive transmission is connected between the auxiliary transmission output shaft and the differential. The four-wheel drive transmission includes a four-wheel drive shaft connected to the front wheel through the lower portion of the peripheral gear.

Meanwhile, the peripheral speed input shaft extends through the peripheral speed device, and an independent PTO clutch is connected to the extended input shaft portion. The independent PTO clutch includes an independent PTO shaft disposed below the peripheral speed input shaft. The independent PTO shaft is connected to one end of the PTO propulsion shaft and the other end of the PTO propulsion shaft is connected to the rear PTO device. The rear PTO device has a rear PTO axis extending horizontally from the rear of the transmission case. The mid PTO device is connected in the middle of the PTO propulsion shaft. The mid PTO device has a mid PTO axis that projects below the transmission case and is horizontally forward.

The main gear device includes a hydraulic pump having a center line connected to the main shaft input shaft and coinciding with the center line of the input shaft, and a hydraulic motor for transferring the hydraulic pressure provided from the hydraulic pump to the output shaft. The hydraulic motor has a center line located below the center line of the hydraulic pump. By the vertical arrangement of the hydraulic pump and the hydraulic motor, the upper surface of the transmission case can be formed stepped. The stepped surface of the transmission case is a part where the operator's foot is located, and is a flat surface without any protruding portion that impedes the movement of the foot.

The sub transmission is mounted on the sub transmission input shaft connected to the peripheral speed output shaft, the high speed, medium speed and low speed input gear mounted on the sub transmission input shaft to rotate together, the sub transmission output shaft disposed on the sub transmission input shaft, and the sub transmission output shaft. It includes sub-high speed, medium speed and low speed output gears meshed with each input gear. In particular, each middle speed gear disposed in the middle is connected via a sub transmission sleeve, and is selectively engaged according to the movement of the sub transmission sleeve operated by an operator. That is, the sub transmission sleeve is splined to the outer circumferential surface of each medium speed gear, and is moved in the high speed or low speed gear direction at the operator's choice. Further, the medium speed output gear is mounted on the sub transmission output shaft and rotates together, while the high speed and low speed output gear are rotatably fitted to the sub transmission output shaft. Therefore, the power from the sub transmission input shaft is finally transmitted to the sub transmission output shaft through the medium speed output gear.

The four-wheel drive transmission includes a four-wheel drive intermediate gear mounted idlely on the sub-shift input shaft of the sub- transmission. The four-wheel drive input gear is mounted and rotated together at the output direction end of the sub-shift output shaft of the sub- transmission, and the four-wheel drive input gear meshes with the four-wheel drive media gear. In addition, the four-wheel drive intermediate gear is selectively engaged with the four-wheel drive output gear. The four-wheel drive output gear is splined to the four-wheel drive shaft extending through the lower portion of the main gear. Therefore, by the operator moving the four-wheel drive output gear, the four-wheel drive medium gear and the output gear are selectively engaged, so that power from the sub transmission output shaft is selectively transmitted to the four-wheel drive shaft.

The independent PTO clutch includes a PTO first input gear mounted to a peripheral speed input shaft extending from the peripheral speed device. The PTO connecting shaft is disposed below the main shaft input shaft, and the PTO connecting gear meshed with the PTO first input gear is mounted to the PTO connecting shaft. The PTO transmission shaft is disposed below the PTO connecting shaft, and the PTO second input gear meshed with the PTO connecting gear is fitted to the PTO transmission shaft so as to be idle. A PTO output gear that rotates with the PTO transmission shaft is mounted to the PTO transmission shaft, and the PTO sleeve is splined to the PTO output gear. Thus, in accordance with the selective movement of the PTO sleeve, the PTO second input gear and the PTO output gear are selectively coupled via the PTO sleeve. The PTO transmission shaft is connected to the PTO propulsion shaft extending to the rear of the transmission case. On the other hand, the PTO connecting shaft and the connecting gear are used for arranging the PTO shift shaft at the same height as the rear PTO apparatus, and if by design the PTO transmission shaft and the rear PTO apparatus are guaranteed to be disposed at the same height without additional means. However, it is not necessary to use PTO connecting shafts and connecting gears.

The mid PTO device includes a mid PTO drive shaft protruding downward of the transmission case and horizontally disposed forward. The mid PTO drive shaft is equipped with a mid PTO output gear, and the mid PTO output gear meshes with the mid PTO input gear mounted to the PTO propulsion shaft. Here, the mid PTO input gear and the output gear may be directly engaged, but if it is impossible to directly engage due to the height difference between the preset PTO propulsion shaft and the mid PTO driving shaft, it may be engaged using at least one gear.

The rear PTO device includes a rear PTO input gear mounted to the PTO propulsion shaft. A rear PTO drive shaft protruding horizontally to the rear of the transmission case is disposed above the PTO propulsion shaft. A rear PTO output gear, optionally engaged with the rear PTO input gear, is splined to the rear PTO drive shaft. A shift fork adjusted by an operator is connected to the rear PTO output gear so that the rear PTO output gear is moved on the rear PTO drive shaft by the shift fork. The shift fork can be operated by a shift lever or a button provided in the driver's seat. Thus, since the rear PTO input and output gears are selectively engaged by the shifting fork, it is possible to operate only the mid PTO device.

Hereinafter, a transmission of a tractor according to a preferred embodiment of the present invention will be described in detail with reference to the drawings, but the present invention is not limited or limited by the following embodiments.

1 is a cross-sectional view showing the entire transmission according to the present invention, FIG. 2 is an enlarged cross-sectional view showing a peripheral gear device in the transmission shown in FIG. 1, and FIG. 3 is an enlarged view of the sub transmission device in the transmission shown in FIG. 4 is an enlarged cross-sectional view of a four-wheel drive transmission in the transmission shown in FIG. 1, FIG. 5 is an enlarged cross-sectional view of an independent PTO clutch in the transmission shown in FIG. 1, and FIG. 6 is FIG. Figure 11 is an enlarged cross-sectional view of the mid PTO device in the transmission shown in Figure 7, Figure 7 is an enlarged cross-sectional view of the rear PTO device in the transmission shown in Figure 1, Figures 8a to 8c is a peripheral speed of the transmission according to the present invention and In order to explain the forward / backward shifting operation by the sub transmission, a sectional view showing only the peripheral speed and the sub transmission is shown in the transmission of FIG. 1. 8A is a view showing a power transmission path of a sub-speed intermediate speed, FIG. 8B is a view showing a power transmission path of a sub-speed high speed stage, FIG. 8C is a view showing a power transmission path of a sub-speed low speed stage, FIG. 9 is a cross-sectional view showing a four-wheel drive transmission in addition to the diagram of Figure 8 to explain that power is transmitted to the front wheels by the four-wheel drive transmission of the transmission according to the present invention, Figures 10 and 11 To illustrate that power is transmitted from the transmission to the mid PTO and the rear PTO device, a cross-sectional view showing only the independent PTO clutch, the mid PTO and the rear PTO device in the transmission of FIG. 1 is shown. FIG. 11 is a cross-sectional view illustrating a state in which power transmission is blocked by the PTO device, and FIG. 11 is a view in which power is transmitted only to the rear PTO device and power is cut off by the mid PTO device. To a cross-sectional view.

1 shows the entire transmission of a tractor according to the invention. As shown in FIG. 1, the transmission case is arranged inside the transmission case 1. In a tractor, the upper part of the transmission case 1 becomes a cabin in which an operator sits and adjusts a tractor. That is, the upper surface of the transmission case 1 is a part where the operator's foot is placed, and various pedals such as an accelerator pedal and a brake pedal are provided on the upper surface. In particular, the upper surface of the transmission case 1 has a stepped shape, and the stepped surface 2 on which various pedals are installed has a flat surface without any protruding portion. Therefore, when the worker moves the foot, there is no obstacle. This effect is made possible by an appropriate arrangement of the components of the transmission according to the invention, which will be described later.

In FIG. 1, an engine is arranged on the left side of the transmission case 2 so that power from the engine is transmitted via transmission to a front wheel or work machine mounted on each PTO device.

The transmission according to the present invention is largely, the peripheral gear device 10 to receive the power of the engine to perform the forward and rearward shift, and the power transmission from the peripheral gear device 10 to perform a three-speed shift to the differential device 30 ) And the sub transmission 20 for transmitting to the longitudinal reduction gear, the four-wheel drive transmission 70 for transmitting the power shifted from the sub transmission 20 to the front wheel, and the engine without passing through the peripheral gear 10 Independent PTO clutch 40 that receives power directly and selectively intercepts power transmission, and mid PTO device 50 and rear PTO device 60 that selectively drive power from independent PTO clutch 40 to drive a work machine. Is made of.

For reference, in FIG. 1, the independent PTO clutch 40 and the four-wheel drive transmission 70 are disposed in the exposed state of the lower portion of the transmission case 2 in front of the mid PTO device 50. However, this arrangement structure is intended to show all the components according to the present invention in one drawing, and as shown in FIGS. 10 and 11, in fact, an independent PTO clutch 40 and a four-wheel drive transmission 70. Is housed inside the transmission case 2 and is not exposed to the bottom of the transmission case 2 at all. Therefore, there is no obstacle in front of the mid PTO apparatus 50, and as a result, it is very easy to attach the work machine to the mid PTO apparatus 50.

The transmission according to the present invention largely divided as described above will be described in detail with reference to the accompanying drawings for each component.

First, the main gear device 10 is shown enlarged in FIG. Referring to FIG. 2, engine power is transmitted to the peripheral speed input shaft 11. The hydraulic pump 12 is connected to the main shaft input shaft 11, so that the swash plate (not shown) disposed inside the hydraulic pump 12 is inclined at a predetermined angle according to the direction and degree of the operator's stepping on the accelerator pedal. Discharge. The discharged hydraulic pressure is transmitted to the hydraulic motor 13, and the central axis of the hydraulic motor 13 is disposed below the central axis of the hydraulic pump 12. The power of the hydraulic motor 13 driven by the discharge oil pressure is transmitted to the peripheral speed output shaft 14. Therefore, the peripheral speed input shaft 11 is arranged in the upper part, and the peripheral speed output shaft 14 is arranged in parallel to the lower part. Due to the arrangement structure of the main shaft input shaft 11 and the output shaft 14, that is, the height difference, the upper surface of the transmission case 1 can form the stepped surface 2 by the height difference. It can be exercised. On the other hand, the peripheral speed input shaft 11 extends to the right beyond the hydraulic pump 12.

A sub transmission device 20 that receives power from the main transmission device 10 and performs sub gearing in three steps is shown in detail in FIG. 3. Referring to FIG. 3, the sub transmission input shaft 21 is connected to the peripheral speed output shaft 13 of the peripheral speed device 10. The sub transmission output shaft 22 is disposed in parallel with the upper portion of the sub transmission input shaft 21. The high speed, medium speed and low speed input gears 24, 23 and 25 are mounted to the sub transmission input shaft 21 to rotate together with the sub transmission input shaft 21. The high speed input gear 24 is disposed at the left side, the low speed input gear 25 is disposed at the right side, and the medium speed input gear 23 is disposed at the center.

The high speed, medium speed and low speed output gears 27, 26 and 28 are fitted to the sub transmission output shaft 22. As shown in FIG. The high speed and low speed output gears 27 and 28 are fitted to the sub transmission output shaft 22 so as to be idle, and are not linked to the rotation of the sub transmission output shaft 22. Only the medium speed output gear 26 is attached to the sub transmission output shaft 22 and rotates together. In addition, the high speed and low speed input gears 24 and 25 and the high speed and low speed output gears 27 and 28 are engaged so that power from the input gears 24 and 25 is directly transmitted to the output gears 27 and 28. However, since the high speed and low speed output gears 27 and 28 are idlely fitted to the sub speed output shaft 22, the sub speed output shaft 22 does not rotate by the high speed and low speed output gears 27 and 28.

Meanwhile, the medium speed input gear 23 and the medium speed output gear 26 are connected via the sleeve 29. The sleeve 29 is splined on the medium speed input and output gears 23 and 26 and is moved axially by the operator's operation. In particular, the medium speed output gear 26 is considerably longer in axial length than the slave input gear 23. Thus, when the sleeve 29 is moved to the left or the right and is engaged with the high speed or low speed output gears 27 and 28, the sleeve 29 is completely separated from the medium speed input gear 23 but is in the medium speed output gear. In (26), it remains in a coupled state. As a result, the power transmission from the sub transmission input shaft 21 to the sub transmission output shaft 22 is always transmitted only through the medium speed output gear 26. The sub transmission output shaft 22 which receives the power shifted in the manner described above is connected to the differential device 30. The differential device 30 is connected to the rear wheels via a longitudinal reduction gear, so that engine power is finally transmitted to the rear wheels.

4 shows a four-wheel drive transmission 70 that selectively transfers power transmitted from the sub transmission 20 to the differential 30 to the front wheels as well. Referring to FIG. 4, a four-wheel drive input gear 72 is mounted on the sub transmission output shaft 22 of the sub transmission 20 connected to the differential device 30. The four-wheel drive intermediate gear 73 meshed with the four-wheel drive input gear 72 is fitted to the sub transmission input shaft 21 of the sub transmission 20 so as to be idling. The 4WD output gear 74 is meshed with the 4WD medium gear 73, and the 4WD output gear 74 is splined to the 4WD drive shaft 71 connected by the front wheels. The four-wheel drive shaft 71 passes through the lower portion of the main gear device 10 and is connected to the front wheel. Therefore, by the operator operating the four-wheel drive shift lever, the four-wheel drive output gear 74 is moved on the four-wheel drive shaft 71 to be selectively engaged with the four-wheel drive mediated gear 73, whereby the sub-shift output shaft 22 ) Is selectively transmitted to the four-wheel drive shaft (71). Here, the four-wheel drive medium gear 73 is used for the height difference correction between the sub-shift output shaft 22 and the four-wheel drive shaft 71, it is not a necessary component.

Since the tractor must have a PTO device that functions to operate a work machine in addition to the above-described forward and backward shifting and four-wheel drive shifting operation, an independent PTO clutch 40 for selectively operating the PTO device is provided in the tractor.

An independent PTO clutch 40 is shown in detail in FIG. 5. As shown in FIG. 5, the peripheral speed input shaft 11 extends to the right through the hydraulic pump 12. The first PTO input gear 44 is mounted to the peripheral speed input shaft 11. The PTO connecting shaft 41 is disposed in parallel to the lower portion of the peripheral speed input shaft 11, and the PTO connecting gear 45 is mounted to the PTO connecting shaft 41. The PTO connecting gear 45 and the first PTO input gear 44 are engaged with each other. The PTO transmission shaft 42 is disposed in parallel to the lower portion of the PTO connecting shaft 41. The second PTO input gear 46 is fitted to the PTO transmission shaft 42 so as to be idling, and meshes with the PTO connecting gear 45. In addition, a PTO output gear 47 is mounted to the PTO transmission shaft 42, and a PTO sleeve 48 is splined to the PTO output gear 47. Thus, the operator selectively engages the second PTO input gear 46 and the PTO output gear 47 by manipulating the PTO sleeve 48. The PTO transmission shaft 42 is connected to the PTO propulsion shaft 43 extending to the rear end of the transmission case 1. On the other hand, in the present embodiment exemplified a structure in which the PTO connecting shaft 41 and the PTO connecting gear 45 is employed, since it is used for the height difference correction between the PTO transmission shaft 42 and the peripheral speed input shaft 11 If the height difference correction is secured, the first and second PTO input gears 44 and 46 may be directly connected without using the PTO connecting shaft 41 and the PTO connecting gear 45.

FIG. 6 shows a mid PTO apparatus 50 for selectively receiving power from the PTO propulsion shaft 43 to operate the mid work machine. Referring to FIG. 6, a mid PTO input gear 54 is mounted at the middle portion of the PTO propulsion shaft 43. The first mid PTO connecting shaft 51 is disposed in parallel to the lower portion of the PTO propulsion shaft 43. The first connecting gear 55 is mounted to the first mid PTO connecting shaft 51 and meshes with the mid PTO input gear 54. The second mid PTO connecting shaft 52 is disposed parallel to the lower portion of the first mid PTO connecting shaft 51. The second connecting gear 56 is mounted to the second mid PTO connecting shaft 52 and meshes with the first connecting gear 55. The mid PTO drive shaft 53 is disposed parallel to the lower part of the second mid PTO connecting shaft 52, and protrudes from the transmission case 1 to face the front of the tractor. The mid PTO output gear 57 is splined to the mid PTO drive shaft 53 and meshes with the second connecting gear 56. The mid PTO output gear 57 is selectively engaged with the second connecting gear 56 while being moved on the mid PTO drive shaft 53 by the operator's operation. Therefore, the power of the PTO propulsion shaft 43 is selectively transmitted to the mid PTO drive shaft 53.

A rear PTO device 60 that selectively receives the power of the PTO propulsion shaft 43 together with the mid PTO device 50 is shown in FIG. 7. As shown in FIG. 7, the PTO propulsion shaft 43 is rotatably supported at the rear end of the transmission case 1. The rear PTO input gear 62 is mounted to the PTO propulsion shaft 43. The rear PTO drive shaft 61 is disposed in parallel to the upper portion of the PTO propulsion shaft 43 and protrudes through the rear of the transmission case 1. The rear PTO output gear 63 splined to the rear PTO drive shaft 61 is meshed with the rear PTO input gear 62. The rear PTO output gear 63 is moved on the rear PTO drive shaft 61 by the shifting fork 64 adjusted by the operator, and is selectively engaged with the rear PTO input gear 62. On the other hand, the shift fork 64 can be operated with a shift lever or a button.

Hereinafter, the shift operation will be described in detail by shift stage by the transmission according to the present embodiment configured as described above.

First, since the shifting forward and backward by the main gear device 10 is automatically performed according to the direction and degree of the operator stepping on the accelerator pedal, the description of the shift operation by the main gear device 10 is omitted here.

Subshift middle speed

8A illustrates a path in which power is transmitted by shifting from the sub transmission 20 to the middle speed. As shown in FIG. 8A, the sub transmission sleeve 29 is engaged with the medium speed input gear 23. Therefore, the power is transmitted to the differential device 30 via the sub transmission input shaft 21 → the medium speed input gear 23 → the sub transmission sleeve 29 → the medium speed output gear 26 → the sub transmission output shaft 22.

Sub-speed high-speed

8B illustrates a path in which power is transmitted by shifting from the sub transmission 20 to the high speed stage. As shown in FIG. 8B, the sub transmission sleeve 29 moves on the medium speed output gear 26 and is engaged with the high speed output gear 27. Therefore, the power is differentially transmitted via the sub transmission input shaft 21 → the high speed input gear 24 → the high speed output gear 27 → the sub transmission sleeve 29 → the medium speed output gear 26 → the sub transmission output shaft 2. Delivered to (30).

Sub-speed low speed

8C shows a path in which power is transmitted by shifting from the sub transmission 20 to the low speed stage. As shown in FIG. 8C, the sub transmission sleeve 29 moves on the medium speed output gear 26 and is engaged with the low speed output gear 28. Therefore, the differential power is transmitted via the sub transmission input shaft 21 → the low speed input gear 25 → the low speed output gear 28 → the sub transmission sleeve 29 → the medium speed output gear 26 → the sub transmission output shaft 2. Delivered to (30).

4-wheel drive

9 illustrates a path through which power shifted by the sub transmission 20 is transmitted to the front wheel as well as the rear wheel. Referring to FIG. 9, the 4WD output gear 74 is engaged with the 4WD medium gear 73. Therefore, the power from the sub transmission device 20 transfers the sub transmission output shaft 22 to the four-wheel drive input gear 72 to the four-wheel drive intermediate gear 73 to the four-wheel drive output gear 74 to the four-wheel drive shaft 71. It is transmitted to the front wheel by way of.

Mid PTO Device

In FIG. 10, power is transmitted only to the mid PTO device 50 and power transmission is blocked to the rear PTO device 60. As shown in FIG. 10, the mid PTO output gear 57 is engaged with the second coupling gear 56, while the rear PTO input and output gears 62, 63 are not engaged. Therefore, the power transmitted to the PTO propeller shaft 43 through the independent PTO clutch 40 is transmitted from the mid PTO input gear 54 to the first connecting gear 55 to the second connecting gear 56 to the mid PTO output gear 57. ? Is transmitted to the work machine through the mid PTO drive shaft 53. On the other hand, power is not transmitted to the rear PTO drive shaft 61.

Rear PTO device

In FIG. 11, power is transmitted only to the rear PTO device 60 and power transmission is blocked to the mid PTO device 50. As shown in FIG. 11, the mid PTO output gear 57 is separated from the second connecting gear 56, while the rear PTO input and output gears 62, 63 are engaged. Therefore, the power transmitted to the PTO propulsion shaft 43 through the independent PTO clutch 40 passes through the mid PTO device 50 through the mid PTO input gear 54 → the first connecting gear 55 → the second connecting gear ( Up to 56 and not to mid PTO output gear 57. On the other hand, it is transmitted to the work machine through the rear PTO input gear 62 → rear PTO output gear 63 → rear PTO drive shaft 61 via the rear PTO device 60.

Here, in the description of the operation in the present embodiment, it is illustrated that the power is transmitted only to any one of the mid PTO device 50 or the rear PTO device 60, but it is not necessarily the case, both devices (50, 60) Of course, power may be transmitted to both, or power may not be transmitted to both devices 50 and 60. That is, the independent PTO clutch 40 may completely shut off power transmission to both devices 50 and 60, but may separately control each device 50 and 60 to block power transmission.

As described above, according to the present invention, since the various devices are optimally disposed in the narrow space of the transmission case, the transmission structure becomes compact while maintaining the power transmission efficiency optimally.

In addition, since there is no obstacle in the front space of the mid PTO apparatus, the work machine can be easily attached to the mid PTO apparatus.

In addition, since the power can be prevented from being transmitted to the rear PTO device or vice versa during the operation of the mid PTO device, power loss is prevented.

In the above, the transmission of the tractor according to the preferred embodiment of the present invention has been described and illustrated, but the present invention is not limited to the above-described embodiment, and the present invention without departing from the gist of the present invention as claimed in the following claims. Anyone with ordinary knowledge in the field will understand that various changes can be made.

Claims (16)

Peripheral speed device for receiving power from the engine to perform the front and rear shifting; A sub transmission device configured to receive power from the peripheral speed transmission device and transmit the power to the rear wheels by performing a plurality of speed shifts; A four-wheel drive transmission for selectively transmitting power from the sub transmission to the front wheels; An independent PTO clutch that receives power from the engine separately from the peripheral gear device and selectively interrupts power transmission; A mid PTO device selectively receiving power from the independent PTO clutch; And And a rear PTO device selectively receiving power from the independent PTO clutch. The method of claim 1, The peripheral device is Peripheral speed input shaft connected to the engine; A hydraulic pump receiving power from the peripheral speed input shaft; A hydraulic motor disposed under the hydraulic pump to receive hydraulic pressure discharged from the hydraulic pump; And And a peripheral speed output shaft which is driven by the hydraulic motor and is disposed parallel to the lower part of the peripheral speed input shaft. The method of claim 1, The sub transmission device A sub-shift input shaft connected to an output end of the peripheral gear device; High speed, medium speed, and low speed input gears mounted to the sub-shift input shaft; A sub-shift output shaft disposed in parallel with an upper portion of the sub-shift input shaft; A high speed and low speed output gear fitted to the sub-shift output shaft so as to be idle, and engaged with each of the high speed and low speed input gears; A medium speed output gear mounted to the sub transmission output shaft and rotated together; And And a sub transmission sleeve that is splined to the medium speed output gear and engaged with the medium speed input gear, and selectively coupled to the high speed output gear or the low speed output gear according to the operator's operation. The method of claim 1, The four-wheel drive transmission device A four-wheel drive input gear connected to an output end of the sub transmission; A four-wheel drive output gear meshed with the four-wheel drive input gear; And And the four-wheel drive output gear is spline-coupled and includes a four-wheel drive shaft extending through the lower portion of the main transmission device and connected to the front wheels. The method of claim 1, The independent PTO clutch A first PTO input gear that receives power directly from the engine; A second PTO input gear meshed with the first PTO input gear; A PTO drive shaft to which the second PTO input gear is idle; A PTO output gear mounted to the PTO drive shaft and rotated together; A PTO sleeve splined to said PTO output gear, said PTO sleeve selectively coupled to said second PTO input gear; And Transmission of a tractor comprising a PTO propulsion shaft connected to the PTO drive shaft. The method of claim 1, The mid PTO device A mid PTO input gear connected to an intermediate portion of the independent PTO clutch; A mid PTO output gear meshed with the mid PTO input gear; And And the mid PTO output gear is spline-coupled and includes a mid PTO drive shaft exposed from the lower portion of the transmission case and disposed toward the front wheels. The method of claim 1, The rear PTO device is A rear PTO input gear connected to an end of said independent PTO clutch; A rear PTO output gear meshed with the rear PTO input gear; A rear PTO drive shaft spline-coupled to the rear PTO output gear and protruding from the rear of the transmission case; And And a shift fork for selectively engaging the rear PTO output gear with the rear PTO input gear. A peripheral speed input shaft connected to an engine, a hydraulic pump receiving power from the peripheral speed input shaft, a hydraulic motor disposed under the hydraulic pump and receiving hydraulic pressure discharged from the hydraulic pump, and driven by the hydraulic motor, A peripheral gear apparatus including a peripheral gear output shaft disposed parallel to a lower portion of the peripheral gear input shaft; A sub-speed input shaft connected to the peripheral speed output shaft of the peripheral speed gear, a high speed, medium speed and low speed input gear mounted to the sub-speed input shaft, a sub-speed output shaft disposed in parallel with an upper portion of the sub-speed input shaft, and the sub-speed output shaft A high-speed and low-speed output gear fitted to the high-speed and low-speed input gear so as to be idling, and a medium-speed output gear mounted to the sub-shift output shaft and rotated together, and spline-coupled to the medium-speed output gear. A sub transmission including a sub transmission sleeve engaged with the high speed output gear or the low speed output gear, wherein the sub transmission sleeve is selectively engaged with the operator; A four wheel drive input gear connected to the sub transmission output shaft of the sub transmission, a four wheel drive connecting gear meshed with the four wheel drive input gear and supported idlely on the sub transmission input shaft, and 4 engaged with the four wheel drive connecting gear A four-wheel drive transmission device including a four-wheel drive output gear and a four-wheel drive shaft spline-coupled and extending through the lower portion of the hydraulic motor of the peripheral gear device and connected to the front wheel; An independent PTO clutch that receives power from the engine separately from the peripheral gear device and selectively interrupts power transmission; A mid PTO device selectively receiving power from the independent PTO clutch; And And a rear PTO device selectively receiving power from the independent PTO clutch. The method of claim 8, The independent PTO clutch A first PTO input gear mounted to a peripheral speed input shaft extended through the hydraulic pump of the peripheral speed device; A second PTO input gear meshed with the first PTO input gear; A PTO drive shaft in which the second PTO input gear is rotatably fitted and disposed in parallel to a lower portion of the peripheral speed input shaft; A PTO output gear mounted to the PTO drive shaft and rotated together; A PTO sleeve splined to said PTO output gear, said PTO sleeve selectively coupled to said second PTO input gear; And Transmission of a tractor comprising a PTO propulsion shaft connected to the PTO drive shaft. The method of claim 8, The mid PTO device A mid PTO input gear connected to an intermediate portion of the independent PTO clutch; A mid PTO output gear meshed with the mid PTO input gear; And And the mid PTO output gear is spline-coupled and includes a mid PTO drive shaft exposed from the lower portion of the transmission case and disposed toward the front wheels. The method of claim 8, The rear PTO device is A rear PTO input gear connected to an end of said independent PTO clutch; A rear PTO output gear meshed with the rear PTO input gear; A rear PTO drive shaft spline-coupled to the rear PTO output gear and protruding from the rear of the transmission case; And And a shift fork for selectively engaging the rear PTO output gear with the rear PTO input gear. Peripheral speed device for receiving power from the engine to perform the front and rear shifting; A sub transmission device configured to receive power from the peripheral speed transmission device and transmit the power to the rear wheels by performing a plurality of speed shifts; A four-wheel drive transmission for selectively transmitting power from the sub transmission to the front wheels; A first PTO input gear that receives power directly from the engine, a second PTO input gear meshed with the first PTO input gear, a PTO drive shaft in which the second PTO input gear is idling, and mounted to the PTO drive shaft. An independent PTO clutch including a PTO output gear rotated together with the PTO output gear, a PTO sleeve selectively splined to the PTO output gear, and a PTO driving shaft connected to the PTO drive shaft; The mid PTO input gear connected to the middle portion of the PTO propulsion shaft of the independent PTO clutch, the mid PTO output gear meshed with the mid PTO input gear, and the mid PTO output gear are splined and exposed at the bottom of the transmission case to secure the front wheels. A mid PTO device comprising a mid PTO drive shaft disposed toward; And A rear PTO input gear connected to an end of the PTO propulsion shaft of the independent PTO clutch, a rear PTO output gear meshed with the rear PTO input gear, and a rear PTO output gear splined and protruding from the rear of the transmission case; And a rear PTO device comprising a shift fork to selectively engage the rear PTO output gear with the rear PTO input gear. The method of claim 12, The peripheral device is A peripheral speed input shaft connected to the engine and equipped with a first PTO input gear of the independent PTO clutch; A hydraulic pump receiving power from the peripheral speed input shaft; A hydraulic motor disposed under the hydraulic pump to receive hydraulic pressure discharged from the hydraulic pump; And And a peripheral speed output shaft which is driven by the hydraulic motor and is disposed parallel to the lower part of the peripheral speed input shaft. The method of claim 12, The sub transmission device A sub-shift input shaft connected to an output end of the peripheral gear device; High speed, medium speed, and low speed input gears mounted to the sub-shift input shaft; A sub-shift output shaft disposed in parallel with an upper portion of the sub-shift input shaft; A high speed and low speed output gear fitted to the sub-shift output shaft so as to be idle, and engaged with each of the high speed and low speed input gears; A medium speed output gear mounted to the sub transmission output shaft and rotated together; And And a sub transmission sleeve that is splined to the medium speed output gear and engaged with the medium speed input gear, and selectively coupled to the high speed output gear or the low speed output gear according to the operator's operation. The method of claim 12, The four-wheel drive transmission device A four-wheel drive input gear connected to an output end of the sub transmission; A four-wheel drive output gear meshed with the four-wheel drive input gear; And And the four-wheel drive output gear is spline-coupled and includes a four-wheel drive shaft extending through the lower portion of the main transmission device and connected to the front wheels. A peripheral speed input shaft connected to an engine, a hydraulic pump receiving power from the peripheral speed input shaft, a hydraulic motor disposed under the hydraulic pump and receiving hydraulic pressure discharged from the hydraulic pump, and driven by the hydraulic motor, A peripheral gear apparatus including a peripheral gear output shaft disposed parallel to a lower portion of the peripheral gear input shaft; A sub-speed input shaft connected to the peripheral speed output shaft of the peripheral speed gear, a high speed, medium speed and low speed input gear mounted to the sub-speed input shaft, a sub-speed output shaft disposed parallel to the upper portion of the sub-speed input shaft, and the sub-shift A medium speed output gear splined to the medium speed output gear and spline coupled to the medium speed output gear, the medium speed output gear mounted to the output shaft and engaged with each of the high speed and low speed input gears, the medium speed output gear mounted to the sub transmission output shaft, and rotated together. A sub transmission including a sub transmission sleeve engaged with the gear and selectively engaged with the high speed output gear or the low speed output gear according to an operator's operation; A four wheel drive input gear mounted to the sub transmission output shaft of the sub transmission device, a four wheel drive connecting gear meshed with the four wheel drive input gear and supported idlely on the sub transmission input shaft, and four engaged with the four wheel drive connecting gear; A four-wheel drive transmission device including a four-wheel drive output gear and a four-wheel drive shaft spline-coupled and extending through the lower portion of the hydraulic motor of the peripheral gear device and connected to the front wheel; A first PTO input gear mounted to a peripheral speed input shaft extending from the peripheral speed device and directly receiving power from the engine, a second PTO input gear meshed with the first PTO input gear, and the second PTO input A PTO drive shaft in which a gear is rotatably fitted, a PTO output gear mounted on the PTO drive shaft and rotated together, a PTO sleeve splined to the PTO output gear and selectively coupled to the second PTO input gear, and the PTO drive shaft An independent PTO clutch including a PTO propulsion shaft connected thereto; The mid PTO input gear mounted to the middle portion of the PTO propulsion shaft of the independent PTO clutch, the mid PTO output gear meshed with the mid PTO input gear, and the mid PTO output gear are splined together and exposed from the lower part of the transmission case to secure the front wheels. A mid PTO device comprising a mid PTO drive shaft disposed toward; And A rear PTO input gear mounted to an end of the PTO propulsion shaft of the independent PTO clutch, a rear PTO output gear meshed with the rear PTO input gear, and a rear PTO drive shaft splined and protruding from the rear of the transmission case; And a rear PTO device comprising a shift fork to selectively engage the rear PTO output gear with the rear PTO input gear.