KR20070098488A - Pto transmission structure for tractor - Google Patents

Abstract

A PTO(power takeoff) transmission structure for a tractor is provided to facilitate power transmission in a selected PTO mode by simplifying the PTO transmission structure. A PTO transmission structure for a tractor comprises a rear PTO shaft(12) provided at a rear portion of the PTO transmission structure and a middle PTO shaft(13) provided at a lower portion of the PTO transmission structure. A PTO mode selection unit(66) is disposed on a PTO transmission shaft of the tractor to selectively output power to the rear mode PTO shaft or the middle PTO shaft. A one-way clutch(46) and a PTO clutch(47) are provided at an upper portion of the PTO mode selection unit. The one-way clutch, the PTO clutch and the PTO mode selection unit are concentrically arranged.

Description

PTO TRANSMISSION STRUCTURE FOR TRACTOR

1 is a full side view of a tractor;

2 is a longitudinal side view of the front wheel transmission structure;

3 is a longitudinal side view showing the entire transmission structure;

4 is a schematic diagram showing a gear train of the entire transmission structure.

5 is a longitudinal side view of the front wheel shift mechanism in the standard four-wheel drive mode;

6 is a longitudinal side view of the front wheel shift mechanism in the front wheel speed drive mode;

7 is a hydraulic circuit diagram.

8 is a longitudinal side view of a PTO transmission structure;

9 is a longitudinal side view of the PTO transmission structure;

10 is a longitudinal side view of the PTO transmission structure;

Fig. 11 is a side view showing the operation structure of the PTO mode selection mechanism.

Fig. 12 is a front view showing the operation structure of the PTO mode selection mechanism.

Fig. 13 is a longitudinal side view showing the entire transmission structure of another embodiment.

14 is a schematic diagram showing a gear train of the entire transmission structure of another embodiment.

<Explanation of symbols for main parts of the drawings>

12: rear PTO shaft

13: mid PTO shaft

45: electric shaft

46: one-way clutch

47: PTO Clutch

66: PTO mode selection mechanism

3mw: Bearing Wall

e: euro

f: internal flow path

V4: Operation Valve

[Document 1] Japanese Unexamined Patent Application Publication No. 5-162551

[Document 2] Japanese Patent Application Laid-Open No. 7-277017

The present invention relates to a PTO transmission structure of a tractor having a rear PTO shaft and a mid PTO shaft.

In the PTO transmission structure, when the main clutch is turned off, the driving force due to the inertia rotation of the work device driven by the rear PTO shaft or the mid PTO shaft is transmitted to the traveling transmission system, thereby avoiding the movement of the body. In many cases, the electric system interposes one-way clutches.

For example, Japanese Patent Laid-Open No. 5-162551 (FIG. 5) transmits power for driving a PTO via a one-way clutch to the rear PTO shaft, the mid PTO shaft, or both through the PTO mode selection means. A PTO transmission structure configured to be disclosed is disclosed. Japanese Patent Laid-Open No. 7-277017 discloses a PTO transmission structure in which a transmission system of a rear PTO shaft and a transmission system to a mid PTO shaft are respectively interposed through a one-way clutch.

In the above-described conventional structure, by introducing the one-way clutch, the driving force due to the inertia rotation of the work device driven by the rear PTO shaft or the mid PTO shaft is transmitted to the traveling electric system, and the movement of the gas can be avoided. It is also possible to arbitrarily select the driving of the rear PTO shaft only, the driving of the mid PTO shaft only, and the driving of both PTO shafts. However, there is room for improvement in the structure of transmitting / blocking power in any PTO mode selected.

In the PTO transmission structure disclosed in Japanese Unexamined Patent Application Publication No. 5-162551, a neutral position is provided in the operation region of the shift sleeve in the PTO mode selection means, and the PTO mode selection means includes the selection of the PTO mode and the PTO clutch. It has both functions. When power transmission is again performed after the power transmission to the PTO shaft is interrupted, it is necessary to perform a mode selection operation every time, and operation becomes cumbersome. In the middle of moving a shift sleeve to a neutral position, it may pass the selection position of the PTO mode which is not selected, and may drive the PTO shaft which was stopped although it is momentary.

In the PTO transmission structure disclosed in Japanese Patent Laid-Open No. 7-277017, the electric transmission is interrupted by the operation of the shift gear provided in each of the electric system of the rear PTO shaft and the electric system of the mid PTO shaft. The operation pattern of the two shift gears selects the PTO mode and interrupts transmission transmission. Therefore, in the PTO mode which drives both the rear PTO shaft and the mid PTO shaft, for example, it is necessary to operate two shift gears in order to stop driving, and operation becomes cumbersome.

The present invention has been made in view of this point, and even if the work device is mounted on either the rear PTO shaft or the mid PTO shaft, the inertial rotational force of the work device is prevented from being transmitted to the traveling system, and the power interruption in the selected PTO mode is prevented. The main object of the present invention is to provide a compact structure of the PTO transmission structure which can be easily performed.

The tractor's transmission structure according to the first aspect of the present invention is a tractor having a traveling system transmission shaft and a PTO transmission shaft that receive power from the engine via a main clutch, and having a rear PTO shaft at the rear of the body, PTO transmission structure of the tractor with the mid PTO shaft,

On the PTO transmission shaft, a PTO mode selection mechanism for switching and selecting the output form to the rear PTO shaft and the mid PTO shaft is arranged, and a one-way clutch and a PTO clutch are arranged on the motorized upper side of the PTO mode selection mechanism. It is characterized by doing. Of

According to the above configuration, even if any PTO mode is selected by the PTO mode selection mechanism, the one-way clutch stops the reverse transmission of the driving force by the inertia rotation of the connected work device to the traveling system.

Even if any PTO mode is selected by the PTO mode selection mechanism, power can be interrupted or transmitted by the PTO clutch while maintaining the PTO mode.

Therefore, according to the first invention, even if the work device is mounted on either the rear PTO shaft or the mid PTO shaft, the inertial rotational force of the work device can be prevented from being reversely transmitted to the traveling system, and the power in the selected PTO mode can be prevented. Interruption can be performed easily.

In the transmission structure of the tractor which concerns on 2nd invention, the said one-way clutch is arrange | positioned above the PTO clutch.

According to the above configuration, by turning off the PTO clutch, it is possible to prevent transmission of the inertia rotation of the PTO transmission system thereafter to the one-way clutch, and make the one-way clutch small.

In the transmission structure of the tractor which concerns on 3rd invention, the said one-way clutch, the PTO clutch, and the PTO mode selection mechanism are arrange | positioned continuously on the same shaft center.

According to the said structure, each transmission member in a one-way clutch, a PTO clutch, and a PTO mode selection mechanism can be shared. For example, when the one-way clutch is located above the PTO clutch, the driven side transmission member of the one-way clutch can be used as the drive side transmission member of the PTO clutch, so that the one-way clutch and the PTO clutch can be compactly arranged in the axial direction. do. The same applies to the PTO clutch and the PTO mode selection mechanism. By making the driven side transmission member of the PTO clutch the driving side transmission member of the PTO mode selection mechanism, the PTO clutch and the PTO mode selection mechanism can be arranged compactly in the axial direction. do.

In the transmission structure of the tractor which concerns on 4th invention, a PTO brake is arrange | positioned under the transmission lower side of the said PTO clutch, and it is comprised so that the said PTO brake may be braked in conjunction with the clutch off operation of the clutch member of the said PTO clutch.

With this structure, the drive to the PTO shaft is eliminated, and when the PTO clutch is turned off, the PTO brake is automatically operated to reliably stop the work device automatically.

The transmission structure of the tractor which concerns on 5th invention attaches and supports the said PTO clutch and PTO mode selection mechanism to a common transmission shaft.

According to the said structure, a PTO clutch and a PTO mode selection mechanism can be pre-assembled and attached to a common transmission shaft, and it becomes effective in improving the assembly workability of the whole transmission structure.

In the transmission structure of the tractor according to the sixth aspect of the invention, the PTO clutch is hydraulically operated, and a flow path for clutch operation is formed inside the transmission shaft, and the flow path is disposed outside the flow path and the case. One operation valve is connected in communication via an internal flow path of a bearing wall supporting the electric shaft.

According to the above configuration, the operation of turning on / off the PTO clutch is light only by operating the operation valve, and even frequent PTO clutch operation can be performed quickly and lightly without fatigue.

1, the whole side surface of the four-wheel drive type agricultural tractor is shown as an example of a work machine. This agricultural tractor has a structure in which a gas body is formed by connecting the clutch housing 2 connected to the rear part of the engine 1 and the mission case 3 via the housing frame 4 made of sheet metal. The front vehicle shaft case 7 with the front wheels 6 for steering is rollably supported by the front frame 5 extending forward from the lower part of the engine 1, and at the same time, the rear part of the mission case 3 is supported. The rear wheel 8 is attached.

The mission case 3 is configured by connecting the front case 3f, the mid case 3m, and the differential case 3d, and the rear case of the reduction case 3e on the left and right sides of the differential case 3d. (8) is axially supported through this. The cylinder case 10 provided with the lift arm 9 is connected to the upper part of the differential case 3d, and the three-point link mechanism 11 for connecting a work device is lifted by the lift arm 9 which is hydraulically driven. It is supposed to be. The rear PTO shaft 12 protrudes backward from the rear surface of the differential case 3d, and the mid PTO shaft 13 protrudes forward from the lower portion of the mid case 3m.

The transmission structure is shown in Figures 2-4. The upper clutch unit 2 is equipped with a single plate dry main clutch 14, and inside the front case 3f, the main gear transmission 15 and the forward and rearward switching unit 16 are provided. ) Is assembled, and the sub gear shifting section 17 is assembled inside the mid case 3m.

The main gear transmission 15 is configured to transmit the engine power input to the input shaft 18 in three stages and transmit the engine power to the intermediate shaft 19, while the forward and reverse switching section 16 is formed on the side of the intermediate shaft 19. It is comprised so that speed power may be transmitted to the output shaft 20 by forward rotation or reverse rotation, and the main gear of 3 steps of forward and 3 steps of reverse may be performed in the front case 3f.

In detail, the small diameter idling gear G1 and the large diameter idling gear G2 are attached to the input shaft 18 of the main gear transmission 15, and between the small diameter and large diameter idling gears G1 and G2. The intermediate gear shift gear G3 is spline-mounted. The intermediate shaft 19 is engaged with the large diameter gear G4 and the small diameter gear G5 and the shift gear G3 which are always engaged with the small diameter idling gear G1 and the large diameter idling gear G2, respectively. Possible medium diameter gear G6 is fixedly installed. By shifting the shift gear G3 to the front position and spline-engaging the boss portion of the small diameter idling gear G1, the low speed idling gear G1 and the large diameter gear G4 have a low speed ( Power is transmitted to the first shaft), and the shift gear G3 is shifted to the front and rear intermediate positions and directly engaged with the middle diameter gear G6, thereby providing power to the intermediate shaft 19 at medium speed (second speed). The transmission is made, and by shifting the shift gear G3 to the rear position and spline-engaging the boss portion of the large diameter idling gear G2, the intermediate shaft (through the large diameter idling gear G2 and the small diameter gear G5) 19), the power is transmitted at a high speed (third speed).

The output shaft 20 is provided with an idling gear G8 for forward rotation that is always engaged with the gear G7 of the intermediate shaft 19, and a reverse gear G10 to the gear G9 of the intermediate shaft 19. The boss part of the forward rotation transmission idling gear G8 which is provided with the idling gear G11 for reverse rotation transmission interlocking | engaged with always being engaged, and shifting the shift sleeve S fitted to the output shaft 20, Alternatively, by selectively engaging the boss portion of the idling gear G11 for reverse rotation transmission, the shifting power of the intermediate shaft 19 is rotated forward or reversely and transmitted to the output shaft 20.

The sub-gear transmission part 17 performs three speed shifts between the transmission shaft 21 coupled to the output shaft 20 and the final output shaft 22 arranged in parallel thereto, The differential mechanism D is driven through the bevel pinion gear Gp provided at the rear end, and the left and right rear wheels 8 are differentially driven.

In detail, the large diameter loose gear G12 and the small diameter loose gear G13 are attached to the front and rear of the electric shaft 21, and the small diameter and large diameter loose gears G12 and G13 are installed. The shift gear G14 which is shift-operated among () is spline-mounted. On the other hand, the final output shaft 22 has a small diameter gear (G15) is always engaged with the large diameter loosely fitted gear (G12), a large diameter gear (G16) is always engaged with the small diameter loosely fitted gear (G13) and The medium diameter gear G17 which can be directly engaged with the shift gear G14 is fixed. By shifting the shift gear G14 backward and engaging the boss portion with the boss portion of the small diameter loosely fitted gear G13, the gear ratio of the small diameter loosely fitted gear G13 and the large diameter gear G16 is reduced. Electric transmission causes "low speed", and shifts the shift gear G14 to the front-rear intermediate position and directly engages with the medium diameter gear G17, thereby transmitting at the gear ratio between the shift gear G14 and the medium diameter gear G17. "Middle speed" is caused by this. By shifting the shift gear G14 forward and engaging the boss portion with the boss portion of the large diameter loosely fitted gear G12, the gear ratio between the large diameter loosely fitted gear G12 and the small diameter gear G15 is obtained. "High speed" is caused by the transmission of.

The output gear G18 for power transmission to the front wheel 6 is fixed to the front end of the final output shaft 22 shifted as mentioned above, and the front wheel is spread over the front case 3f and the mid case 3m. The drive transmission shaft 23 is supported through, and the power extracted from this front wheel drive transmission shaft 23 is axially transmitted to the front vehicle shaft case 7 via the front wheel transmission structure mentioned later. On the rear end of the front-wheel drive electric shaft 23, a shift gear G19 is fitted with a spline, and the shift gear G19 is shifted forward to engage the output gear G18 of the final transmission shaft 22. The four-wheel drive state in which the front-wheel drive power of the speed synchronized with the rear-wheel drive speed is taken out from the front-wheel drive electric shaft 23 is brought about, and the shift gear G19 is shifted backward and the output gear G18 By releasing the engagement with), the front wheel drive is stopped and the rear two-wheel drive state by only the rear wheel 8 is caused.

As shown in FIG. 2, the clutch housing 2 includes a dry clutch chamber a in which the main clutch 14 is accommodated, and a wet (oil bath lubricated) transmission chamber b isolated therefrom. The main transmission shaft 25 which transmits engine power to the input shaft 18 of the said main gear transmission part 15 is inserted through and supported in the upper part of this transmission chamber b, and the transmission chamber b is supported. The front wheel shift mechanism 26 which receives the front wheel drive power taken out from the front wheel drive transmission shaft 23 forward is equipped in the lower part of. The front wheel shift mechanism 26 is provided with an input shaft 28 concentrically connected to the front wheel drive transmission shaft 23 via an intermediate transmission shaft 27 and a transmission shaft 29 parallel thereto. By shifting the transmission clutch 30 provided on the shaft 29 on and off, the transmission shaft 29 is shifted to two stages at high and low gears, and the transmission power is transmitted to the front wheel drive shaft 31 disposed at the lower end of the case. It is comprised so that the high-speed two-speed transmission power taken out from the drive shaft 31 to the front may be transmitted to the axle shaft case 7.

The input shaft 28 is provided with a large diameter gear G20 and a small diameter gear G21, and the shift shaft 29 has a small diameter idling gear always engaged with the large diameter and small diameter gears G20 and G21. G22) and a large diameter idling gear G23 are provided. As shown in FIG. 5, the shift clutch 30 provided in the shift shaft 29 is a spline boss portion connected to the clutch drum 32 and the small diameter idling gear G22 fixed to the shift shaft 29. The piston member 35, which is fitted to the clutch drum 32, with the multi-plate friction transmission unit 34 interposed therebetween, by the pressurized oil and the built-in spring 36 which are delivered and discharged through the in-axis flow path. By advancing and displacing, it is comprised so that the friction transmission part 34 may press-contact or cancel press-contact, and clutch on / off may be performed.

The shift member 37 which is shifted to the boss portion of the clutch drum 32 so as to be shifted outward is integrated with the piston member 35 via a connecting pin 38 penetrating through the clutch drum 32, and the piston member 35. The shift member 37 is shifted integrally with the advancing and moving movement of the &quot;

In the state where the pressure oil supply to the transmission clutch 30 is stopped, as shown in FIG. 5, the piston member 35 is retracted and displaced to the left in the drawing by the built-in spring 36 so that the transmission clutch 30 is moved. In the "off" state, the shift member 37 integrated with the piston member 35 is engaged with the large diameter idling gear G23 from the side, and the power of the input shaft 28 is the small diameter gear G21, After the large diameter idling gear G23, the shifting member 37, and the clutch drum 32 are reduced and transmitted to the speed change shaft 29, it is taken out from the front end of the speed change shaft 29, and through the front wheel drive shaft 31. It is transmitted to the front vehicle shaft case (7). In this case, the front wheels 6 are driven at an ambient speed equivalent to (or slightly faster than around) the rear wheels, so that a standard four-wheel drive mode is exhibited.

As shown in Fig. 6, the piston clutch 35 moves to the right side in the figure against the spring 36 by the supply of pressure oil, and the transmission clutch 30 is turned on by pressing the friction transmission portion 34 in contact. And the shift member 37 integrated with the piston member 35 is disengaged from the large diameter idling gear G23, and the power of the input shaft 28 is driven by the large diameter gear G20 and the small diameter idling gear. (G22) is transmitted to the speed change shaft 29 via the friction transmission portion 34 and the clutch drum 32, and then transmitted to the front vehicle shaft case 7 through the front wheel drive shaft 31. In this case, the front wheels 6 are driven at an ambient speed of about twice the peripheral speed of the rear wheels, so that the front wheel speed drive mode is exhibited.

As shown in the hydraulic circuit diagram of FIG. 7, the hydraulic oil supply / discharge flow path of the shift clutch 30 includes the front wheel control valve V1 and the automatic shift of the front wheel 6 which are switched and operated in conjunction with the steering of the front wheel 6. The automatic transmission selection valve V2 for selecting the on / off and the check valve V3 for switching operation in conjunction with the shift operation of the sub-gear transmission section 17 are arranged in series, and the hydraulic pressure driven by the engine power is provided. After the oil pressure from the pump OP passes through the power steering unit 39 and the oil cooler 40, it is supplied to the front-wheel-speed hydraulic circuit c.

As shown in Figs. 5 and 6, the front wheel control valve V1, the automatic shift selection valve V2 and the check valve V3 are each composed of a rotary valve, and these valves V1, V2, V3 are It is attached to a single valve casing 41 connected to the rear part of the clutch housing 2. And while the front wheel control valve V1 and the check valve V3 are arrange | positioned in parallel, the automatic shift selector valve V2 located in between these spools of valves V1 and V2 in which the spool shaft center differs. It is arranged to be perpendicular to the shaft.

The front wheel control valve V1 is mechanically connected to the steering mechanism 42 of the front wheel 6, and when the front wheel 6 is in a straight state, the flow path is shut off and the front wheel 6 is set from the straight position. When steering to the left or right by an angle (for example, 35 degrees) or more, the front wheel control valve V1 is configured to rotate to open the flow path. In addition, the automatic shift selector valve V2 is linked to the switching lever 43, the flow path is opened at the automatic shift &quot; on &quot; position, and the flow path is blocked at the automatic shift &quot; off &quot; position. In addition, the check valve V3 is linked with the sub-shift lever 44 which switches the sub-gear transmission part 17 which shifts a travel speed to three steps, and the sub-gear transmission part 17 is "low speed. Or the flow path is opened in the state of being operated at "middle speed", and the flow path is blocked in the state in which the sub-gear transmission part 17 is operated at "high speed".

Therefore, the automatic shift selector valve V2 is selected at the automatic shift &quot; on &quot; position to open the flow path, and the sub-gear shift section 17 is operated at &quot; low speed &quot; or &quot; medium speed &quot; Only in the state in which the flow path is opened, the front wheel control valve V1 is switched in conjunction with steering over the set angle of the front wheel 6, the pressure oil is supplied to the transmission clutch 30, and the front wheel 6 is driven at a high speed to smoothly operate the small. The turning is performed at the radius of rotation. Further, even when the automatic shift selector valve V2 is selected at the automatic shifting "on" position, when the sub-gear shifting section 17 is at "high speed", the front wheels automatically speed up even when the front wheels 6 are steered above the set angle. This never happens. In addition, if the automatic shift selector valve V2 is selected at the automatic shift &quot; off &quot; position and the flow path is closed, the front wheel automatic speedup is not naturally performed even by steering of the front wheels 6.

Next, the PTO transmission structure will be described.

The rear end of the input shaft 18, which is penetrated and supported by the upper part of the front case 3f, and the transmission shaft 45 supported over the front case 3f and the mid case 3m are arranged concentrically, The input shaft 18 and the transmission shaft 45 are interlockedly connected through the one-way clutch 46 and the PTO clutch 47 provided at the butt portion. A relay transmission shaft 48 is concentrically connected to the rear end of the transmission shaft 45, and is connected to the small diameter gear G24 and the rear PTO shaft 12 provided at the rear end of the transmission transmission shaft 48. The large-diameter gear G25 provided is engaged, and the rear PTO shaft 12 is driven at a constant speed independently of the traveling system.

As shown in Figs. 3 and 8, the one-way clutch 46 is splined to the rear end of the input shaft 18 so as to be slidable back and forth, and at the same time, the clutch member on the drive side that is pushed backward by the spring 49 ( 50 and a driven transmission member 51 on the driven side that is loosely fitted in the axial center direction without displacement in the front part of the transmission shaft 45, and opposes the clutch member 50 and the transmission member 51 to face each other. At the end, they are interlocked with each other via the slanted hook coupling portion 52. The inclined claw engaging portion 52 is configured such that the driven member 51 of the driven side pushes the clutch member 50 forward against the spring 49 and is displaced, thereby displacing the input shaft 18 with respect to the clutch member 50. The hook inclination direction is set so as to be able to rotate in advance in the rotational direction, and the input shaft 18 is prevented from being rotated by reverse driving from the PTO electric system. That is, when the work device with large rotational inertia is driven to rotate with PTO power, even if the main clutch 14 is turned off to stop running and stops the transmission to the PTO electric system, the input shaft 18 is rotated by the rotational inertia of the work device. It is being avoided that it is driven and driving continues.

The clutch member 50 and the transmission member 51 which comprise the one-way clutch 46 are supported by the bearing 53 at the bearing wall 3fw provided in the rear part of the front part case 3f, and the inclined hook The engaging portion 52 is fitted to the inner circumference of the bearing 53 so as to engage and disengage in a state where it is securely centered.

The PTO clutch 47 is a drum-type transmission member (hereinafter referred to as clutch drum) 51 which is loosely supported at the front of the transmission shaft 45, and a driven side inserted to the transmission shaft 45 on the outside. Multi-plate friction transmission unit 55 interposed between clutch sleeve 54, clutch drum 51 and clutch sleeve 54, and piston member 56 for clutch operation equipped with clutch drum 51 inwardly fitted. ) And a spring 57 for pressing the piston member 56 in the friction release direction (left in FIG. 8). A flow path e is drilled through the transmission shaft 45, and the frictional transmission part (1) is displaced to the right side in Fig. 8 against the spring 57 by the hydraulic oil supplied through the flow path e. 55 is press-contacted to cause a "clutch-on" state, and the pressurized contact of the friction transmission portion 55 is released by releasing the pressure oil supply and displacing the piston member 56 to the left in FIG. 8 with the spring 57. The "clutch off" state is caused.

The flow path e of the transmission shaft 45 is connected to the operation valve V4 provided on the outer surface of the case via the internal flow path f of the bearing wall 3mw provided in the front and middle of the mid case 3m, The PTO clutch 47 is operated on / off by switching the operation valve V4 to the PTO clutch lever 58 provided in the driving section. The operation valve V4 also belongs to a hydraulic system for driving the lift arm 9.

At the rear portion of the PTO clutch 47, a PTO brake 60 is disposed which prevents rotation of the inertia of the electric downward side in association with the "clutch off" operation. The PTO brake 60 is fixed to the clutch sleeve 54 via the stay plate 63 on the friction plate 61 fitted outside the spline, the support plate 62 supporting the friction plate 61 from the rear side, and the front case 3f. When the PTO clutch 47 is turned off and the piston member 56 is pressed by the spring 57 to the left side in the drawing, the clutch sleeve is integrally formed with the piston member 56. 54 moves in the same direction, and the friction plate 61 is supported by the support plate 62 and the brake plate 64 so that the clutch sleeve 54 is braked.

As shown in Fig. 3, the mid PTO case 65 which protrudes and supports the mid PTO shaft 13 toward the front side is connected to the lower surface of the mid case 3m, and the PTO power is applied to the rear PTO shaft ( 12) and a PTO mode selection mechanism 66 for switching and selecting the form to be taken out from the mid PTO shaft 13 are disposed below the PTO clutch 47 by electric transmission.

As for the electric system to the mid PTO shaft 13, the power take-out gear G26 inserted loosely in the rear part of the said transmission shaft 45, and the gear G27 integrally formed in the mid PTO shaft 13 are relay gears. (G28, G29, G30) has a structure interlocked interlocked, the relay gear (G28) is loosely fitted to the front wheel drive transmission shaft 23, and the relay gear (G29) is a transmission shaft 21 of the traveling system ) Is loosely supported, and the relay gear G30 is loosely supported by the support shaft 67 attached to the lower wall part of the mid case 3m.

The PTO mode selection mechanism 66 transfers power only to the rear PTO shaft 12 by shifting the shift member 68 fitted inside the spline in the rear portion of the clutch sleeve 54 in the PTO clutch 47 back and forth. The mode, the mode which transmits power to both the rear PTO shaft 12 and the mid PTO shaft 13, and the mode which transmits power only to the mid PTO shaft 13 are comprised.

As shown in Fig. 9, when the shift member 68 is shifted to the most forward position, the shift member 68 is engaged only with the spool line portion 45a provided on the transmission shaft 45, and the PTO clutch is engaged. Power transmitted to the shift member 68 through 47 is transmitted only to the rear PTO shaft 12 via the relay transmission shaft 48.

As shown in Fig. 8, when the shift member 68 is shifted to the front and rear intermediate positions, the shift member 68 causes the spline portion 45a of the transmission shaft 45 and the boss of the power take-out gear G26. Mid-PTO shaft 13 is brought into the spline meshing state over the portion, and the power transmitted to the shift member 68 through the PTO clutch 47 is transmitted to the rear PTO shaft 12 through the relay transmission shaft 48. The gear is also transmitted.

As shown in Fig. 10, when the shift member 68 is shifted to the rearmost position, the shift member 68 is in a spline mesh with only the boss portion of the power take-off gear G26, and the PTO clutch 47 The power transmitted to the shift member 68 via the gear is transmitted only to the mid PTO shaft 13.

Here, the transmission mode in which only the mid-PTO shaft 13 is driven by the PTO mode selection mechanism 66 is driven by the PTO mode selection mechanism 66 for the shaft connecting sleeve 69 fitted over the transmission shaft 45 and the relay transmission shaft 48 of the PTO system. When is selected, the free rear PTO shaft 12 is configured to prevent rotation around the companion.

The axial coupling sleeve 69 is spline-mounted so as to be shifted back and forth, and its operating system is linked so that the axial coupling sleeve 69 is shifted in the reverse direction in synchronization with the shift member 68 for PTO mode selection. . That is, as shown in Figs. 11 and 12, the operation shaft 70 provided with the eccentric operation pin 70a engaged with the shift member 68, and the operation arm 71a engaged with the shaft connecting sleeve 69. ) Is provided with an operating shaft 71 penetrated and supported by the side wall of the mid case 3m, and is disposed so as to be able to swing back and forth around the operating pin 70b provided at the outer end of the operating shaft 70 and the support point p. The PTO mode selection lever 72 is interlockedly connected through the rod 73, and the linkage lever 71b extending from the outer end of the operation shaft 71 and the operation pin 70b are connected to the long hole. The shift member 68 and the shaft connecting sleeve 69 are shifted in opposite directions to each other by the forward and backward swing operation of the PTO mode selection lever 72.

Therefore, the shift member 68 is shifted to the foremost position and the front-rear intermediate position, and the transmission mode in which only the rear PTO shaft 12 is driven, or the transmission mode in which both the rear PTO shaft 12 and the mid PTO shaft 13 are driven. In the selected state, the shaft connecting sleeve 69 is at the rearmost position or the front and rear intermediate position of the shift range, and the shaft connecting sleeve 69 at this time functions as a simple shaft joint. As shown in Fig. 10, when the shifting member 68 is shifted to the rearmost position and the transmission mode in which only the mid PTO shaft 13 is driven is selected, the shaft connecting sleeve is linked with the rear shift of the shifting member 68. 69 moves forward, and the front end engaging hook 69a of the axial coupling sleeve 69 engages from the rear to the rib 74 formed on the rear face of the bearing wall 3mw in the mid case 3m. As a result, rotation of the PTO-based transmission shaft 45 and the relay transmission shaft 48 is prevented.

[Other Examples]

(1) As shown in Figs. 13 and 14, the variable displacement hydraulic pump P and the constant displacement hydraulic motor M are replaced with the front case 3f which performs the multi-stage shifting forward and backward. The equipped hydrostatic stepless speed changer (HST) can be connected to the mid case (3m), and can be implemented in such a way that the forward and rearward speed can be continuously shifted. In this case, the one-way clutch 46 is arranged at the rear portion of the input shaft 18 serving as the pump shaft, and at the portion where the rear penetration end thereof is aligned with the PTO-based transmission shaft 45.

(2) The one-way clutch 46 may use a roller type in addition to the above-described engagement type.

(3) The PTO clutch 47 may be constituted by a hook clutch which is operated by an artificial or hydraulic shift operation.

(4) It is also possible to implement the PTO clutch 47 in a form in which the one-way clutch 46 is driven upward.

(5) The PTO mode selection mechanism 66 may be configured in a two-mode switch type that transmits only to either the rear PTO shaft 12 or the mid PTO shaft 13.

According to the present invention, even if the work device is mounted on either the rear PTO shaft or the mid PTO shaft, the inertial rotational force of the work device can be prevented from being transmitted to the traveling system, and the power control in the selected PTO mode can be easily performed. The PTO transmission structure can be compactly constructed.

Claims (6)

A tractor having a traveling system drive shaft and a PTO drive shaft that receives power from the engine via a main clutch, wherein the tractor has a rear PTO shaft at the rear of the body and a PTO transmission structure of the tractor provided with a mid PTO shaft at the bottom of the body. Is, On the PTO transmission shaft, a PTO mode selection mechanism for switching and selecting the output form to the rear PTO shaft and the mid PTO shaft is arranged, and a one-way clutch and a PTO clutch are arranged on the motorized upper side of the PTO mode selection mechanism. PTO transmission structure of the tractor characterized by the above-mentioned. The tractor PTO transmission structure according to claim 1, wherein the one-way clutch is disposed above the PTO clutch transmission. The tractor's PTO transmission structure according to claim 2, wherein the one-way clutch, the PTO clutch, and the PTO mode selection mechanism are continuously disposed on the same shaft center. The tractor's PTO transmission structure according to claim 3, wherein the PTO brake is arranged on the electric downward side of the PTO clutch, and the PTO brake is braked in conjunction with the clutch-off operation of the clutch member of the PTO clutch. The tractor's PTO transmission structure according to claim 3, wherein the PTO clutch and the PTO mode selection mechanism are mounted and supported on a common transmission shaft. The said PTO clutch is hydraulic-actuated, the flow path for clutch operation is formed in the said transmission shaft, and the operation valve arrange | positioned outside this flow path and the case supports the said transmission shaft. The PTO transmission structure of the tractor, which is connected in communication via the internal flow path of the bearing wall.

Images