JP4809492B1 - Power transmission device for tractor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To support a transmission bevel gear and a take-out bevel pinion on the rear side of a rear shaft support holder so as to make it easy to obtain the meshing accuracy between them and to reduce the number of parts.
A rear shaft support holder is detachably attached in a transmission case M, supports a shaft of a second transmission mechanism, and a PTO drive shaft 16 is disposed through the rear shaft support holder and a PTO clutch. A pump power take-out means 60 for transmitting the power of the PTO drive shaft to the hydraulic pump 61 mounted on the outer surface of the front mission case is provided. The pump power take-out means has a transmission bevel gear 62 mounted on the PTO drive shaft, and a take-out bevel pinion 63 meshing with the transmission bevel gear 62 and detachably connected to the pump shaft of the hydraulic pump. A gear holding portion 28e that supports the transmission bevel gear and a pinion holding portion 28f that protrudes rearward and supports the take-out bevel pinion are provided on the back side of the support holder.
[Selection] Figure 1

Description

  The present invention relates to a power transmission device for a tractor having pump power take-out means.

  In the prior art of the power transmission device for a tractor, as disclosed in Patent Document 1, the first and second support walls are provided inside the front mission case disposed between the flywheel housing and the rear mission case. A first chamber communicating with the inside of the flywheel housing, a second chamber in the middle portion, and a third chamber in the rear portion, respectively, and a traveling system for shifting the power of the propulsion shaft in the second chamber. A first speed change mechanism is disposed, a second speed change mechanism for shifting power from the first speed change mechanism is disposed in the third chamber, and a PTO drive shaft is directly coaxially connected to the rear portion of the propulsion shaft. A PTO transmission shaft is connected to the rear of the drive shaft via a PTO clutch, and a rear shaft support holder that forms the back wall of the third chamber is detachably attached to the front transmission case. Only support the shaft Said PTO drive shaft penetrating arrangement has a pump power take-off means for transmitting power of the PTO drive shaft to the hydraulic pump mounted on the outer surface of the rear transmission case between the after shaft support holder and PTO clutch.

  The pump power take-out means has a transmission bevel gear mounted on the PTO drive shaft, and a take-out bevel pinion that meshes with the transmission bevel gear and is detachably connected to the pump shaft of the hydraulic pump.

JP 2006-307955 A

  In the prior art pump power take-out means, the transmission bevel gear is supported on the back side of the rear shaft support holder, but the take-out bevel pinion is supported by a pump holder formed separately from the rear shaft support holder. The pump holder is inserted and attached to the rear transmission case from the outside, and it is difficult for the transmission bevel gear and the extraction bevel pinion to engage with each other, and a separate pump holder from the rear shaft support holder is required. It is a factor to increase.

An object of the present invention is to provide a power transmission device for a tractor that can solve such problems of the prior art.
The present invention provides a power transmission device for a tractor in which a transmission bevel gear and an extraction bevel pinion are supported on the back side of a rear shaft support holder so that the engagement accuracy of both can be easily obtained and the number of parts can be reduced. With the goal.

Specific means for solving the problems in the present invention are as follows.
First, a first transmission mechanism 8 of a traveling system that shifts the power of the propulsion shaft 6 and a second transmission mechanism that shifts the power from the first transmission mechanism 8 are arranged inside the transmission case M, and A PTO drive shaft 16 is directly connected coaxially to the rear portion of the propulsion shaft 6, and a PTO transmission shaft 17 is connected to the rear of the PTO drive shaft 16 via a PTO clutch 18.
A rear shaft support holder 28 supporting the rear portion of the second transmission mechanism and penetrating the PTO drive shaft 16 is detachably mounted in the transmission case M, and the transmission is between the rear shaft support holder 28 and the PTO clutch 18. Pump power extraction means 60 for transmitting the power of the PTO drive shaft 16 to the hydraulic pump 61 mounted on the outer surface of the case M is provided,
The pump power take-out means 60 includes a transmission bevel gear 62 mounted on the PTO drive shaft 16 and a take-out bevel pinion 63 that meshes with the transmission bevel gear 62 and is detachably connected to the pump shaft 61a of the hydraulic pump 61. Have
A gear holding portion 28e that supports the transmission bevel gear 62 and a pinion holding portion 28f that protrudes rearward and supports the take-out bevel pinion 63 are provided on the rear side of the rear shaft support holder 28.

Second, first and second support walls Ma and Mb are provided in the front mission case MF disposed between the flywheel housing F and the rear mission case MR, and the first and second support walls Ma and Mb communicate with the inside of the flywheel housing F. A chamber 20, a second chamber 21 in the middle, and a third chamber 22 in the rear are formed, and a rear shaft support holder 28 that forms the back wall of the third chamber 22 is detachable in the front mission case MF. Attached to the
The first speed change mechanism 8 includes a forward / reverse switching mechanism 8 that shifts the power of the propulsion shaft 6 from the propulsion shaft 6 to the input shaft 37 or from the propulsion shaft 6 to the input shaft 37 via the reverse transmission shaft 29 . As the second speed change mechanism, the multi-speed main speed change mechanism 9 and the counter shaft 38 are provided as the second speed change mechanism between the input shaft 37 and the counter shaft 38 through which the forward / reverse power is transmitted from the forward / reverse switching mechanism 8. The sub-transmission mechanism 10 for transmitting the rear wheel power by shifting the height from the output shaft 47 to the output shaft 47 is arranged in the third chamber 22.

Third, on the front side of the rear shaft support holder 28, the bearing portions of the input shaft 37, the counter shaft 38 and the output shaft 47 are formed in a triangular arrangement, and the gear on the back side of the bearing portion of the counter shaft 38. A holding portion 28e is formed.
Fourth, the rear end of the pinion holding portion 28f of the rear shaft support holder 28 and the rear end of the mounting portion of the hydraulic pump 61 are positioned in front of the rear mission case MR mating surface 70 of the rear end of the front mission case MF. It is characterized by.

According to the present invention, the meshing accuracy of the bevel gear of the pump power take-out means can be easily obtained and the number of parts can be reduced.
That is, according to the first aspect of the present invention, the pump power take-out means 60 supports the take-out bevel pinion 63 by projecting rearward on the rear side of the rear shaft support holder 28 and the gear holding portion 28e that supports the transmission bevel gear 62. By providing the pinion holding portion 28f, it is possible to easily obtain the meshing accuracy between the transmission bevel gear 62 and the take-out bevel pinion 63 and reduce the number of parts for supporting the take-out bevel pinion 63.

  In the invention according to claim 2, the transmission case M is separated and formed into the front mission case MF and the rear mission case MR, the forward / reverse switching mechanism 8 is provided in the second chamber 21 in the front mission case MF, and the third chamber 22 is provided. The main transmission mechanism 9 and the sub-transmission mechanism 10 are disposed, and the rear shaft support holder 28 that forms the back wall of the third chamber 22 is detachably attached to the front transmission case MF. The auxiliary transmission mechanism 10, the rear shaft support holder 28, the pump power take-out means 60, and the like can be assembled very easily.

In the invention according to claim 3, the bearing portions of the input shaft 37, the counter shaft 38 and the output shaft 47 are formed in a triangular arrangement on the front side of the rear shaft support holder 28, and on the back side of the bearing portion of the counter shaft 38. Since the gear holding portion 28e is formed, the front and back bearing portions of the rear shaft support holder 28 can be easily and accurately centered.
In the invention according to claim 4, the rear end of the pinion holding portion 28f of the rear shaft support holder 28 and the rear end of the mounting portion of the hydraulic pump 61 are located on the front side of the rear transmission case MR matching surface 70 of the rear end of the front transmission case MF. Therefore, the pump power take-out means 60 can be stored compactly in the front mission case MF.

It is sectional drawing in the front mission case which shows embodiment of this invention. FIG. It is sectional drawing of a subtransmission mechanism and a front-wheel power extraction mechanism. It is an expanded sectional view of a pump power extraction means. It is a rear view of a front mission case and a rear-axis support holder.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 and 2, reference numeral 1 denotes a power transmission device for a front and rear four-wheel drive tractor. A transmission case M is connected to a rear end side of a flywheel housing F connected to a rear end side of the engine E. The transmission case M has front and rear transmission cases MF and MR, and a transmission T is accommodated therein. The engine E, flywheel housing F, transmission case M, etc. constitute a tractor body.

The transmission T transmits power from the engine E to the propulsion shaft 6 via the flywheel 4 and the buffer mechanism 5, and transmits the propulsion shaft 6 to the four front and rear drive wheels, and the propulsion shaft 6. To the PTO shaft 7.
The traveling drive system of the transmission T includes a hydraulically switched forward / reverse switching mechanism (shuttle device) 8 for converting the power of the propulsion shaft 6 into a mode for taking out the power forward and a mode for taking it out in the reverse direction, and the power after the forward / reverse switching. A manually-switchable main transmission mechanism 9 that shifts four speeds, a manually-switchable sub-transmission mechanism 10 that shifts the power shifted by the main transmission mechanism 9 and a rear wheel (drive wheel) ) And a front-wheel power take-out mechanism 12 for a front-wheel drive system that transmits power after switching between high and low by the auxiliary transmission mechanism 10 to the front wheels (drive wheels).

  In the PTO drive system of the transmission T, a PTO drive shaft 16 is directly coaxially connected to the rear portion of the propulsion shaft 6, and a PTO transmission shaft 17 coaxially provided behind the PTO drive shaft 16 and PTO drive. A PTO clutch 18 that transmits and disengages power from the shaft 16 to the PTO transmission shaft 17 and a speed reduction mechanism 19 that decelerates the power from the PTO transmission shaft 17 and transmits it to the PTO shaft 7 are provided.

  The front mission case MF includes a first support wall Ma and a second support wall Mb spaced apart from each other in the front-rear direction. The first support wall Ma is disposed inside the flywheel housing F in which the flywheel 4 and the buffer mechanism 5 are housed. The first chamber 20 that communicates with the second chamber 21 that houses the forward / reverse switching mechanism 8 is partitioned, and the second support wall Mb is the third chamber 22 that houses the main transmission mechanism 9 and the subtransmission mechanism 10. Is partitioned from the second chamber 21.

The rear transmission case MR has a third support wall Mc and a fourth support wall Md spaced apart from each other in the front-rear direction. The third support wall Mc houses the PTO clutch 18 and communicates with the interior of the third chamber 22. The four chambers 23 and the fifth chamber 24 behind the four chambers 23 are partitioned, and the fourth support wall Md partitions the fifth chamber 24 and the sixth chamber 25 that houses the rear wheel differential mechanism 11.
The first support wall Ma has a large opening Ma1 formed at the center, and a front shaft support holder 27 is attached via a fixture such as a bolt so as to close the opening Ma1. A rear shaft support holder 28 is attached between the four chambers 23 via a fixture such as a bolt so as to partition them into the front and rear. The rear shaft support holder 28 is received by a protrusion formed on the inner peripheral surface of the front mission case MF and fixed with a bolt.

  The propulsion shaft 6 has a front end connected to the buffer mechanism 5, a front portion supported by the front shaft support holder 27, and a rear portion rotatably supported by the second support wall Mb. A reverse transmission shaft 29 is arranged in parallel with the propulsion shaft 6, and the reverse transmission shaft 29 is also rotatably supported by the front shaft support holder 27 and the second support wall Mb at the front and rear portions in the same manner as the propulsion shaft 6. A hydraulic switching type forward / reverse switching mechanism 8 is disposed between the propulsion shaft 6 and the reverse transmission shaft 29.

  The hydraulic switching type forward / reverse switching mechanism 8 includes a forward hydraulic clutch 30 provided on the propulsion shaft 6, and a forward output gear 31 supported on the propulsion shaft 6 so as to be relatively rotatable on the rear side of the forward hydraulic clutch 30. The reverse hydraulic clutch 32, the reverse output gear 33 supported on the propulsion shaft 6 so as to be relatively rotatable on the front side of the reverse hydraulic clutch 32, and the reverse first gear rotatably provided integrally with the front portion of the reverse transmission shaft 29. 1 transmission gear 34 and reverse 2nd transmission gear 35 provided in the rear part of reverse transmission shaft 29 so that rotation was possible integrally.

Both the forward output gear 31 and the reverse second transmission gear 35 are engaged with an input gear 36 for inputting power to the main transmission mechanism 9, and the reverse first transmission gear 34 is engaged with the reverse output gear 33.
The forward / reverse switching mechanism 8 transmits the forward rotation power of the propulsion shaft 6 to the input gear 36 by operating the forward hydraulic clutch 30 and operates the reverse hydraulic clutch 32 to operate the reverse output gear 33, the reverse first gear. The forward rotation power of the propulsion shaft 6 is reversely transmitted to the input gear 36 via the first transmission gear 34, the reverse transmission shaft 29 and the reverse second transmission gear 35.

The forward / reverse switching mechanism 8 can connect / disconnect the power transmitted from the engine E to the travel drive system by disconnecting both the forward hydraulic clutch 30 and the reverse hydraulic clutch 32, so that it also serves as a travel system main hydraulic clutch. Yes.
1 to 5, a manually-switchable main transmission mechanism 9 includes an input shaft 37 that has the input gear 36 and receives power from the forward / reverse switching mechanism 8, and a counter shaft 38 that is parallel to the input shaft 37. Between. The counter shaft 38 is a cylindrical shaft that is externally fitted to the PTO drive shaft 16, and both the counter shaft 38 and the input shaft 37 have a front portion on the second support wall Mb and a rear portion on the rear shaft support holder 28, respectively. It is supported rotatably.

The front part of the input shaft 37 protrudes forward from the second support wall Mb, and the input gear 36 is mounted on the front part of the input shaft 37. Between the second support wall Mb and the rear shaft support holder 28, the input shaft 37 is sequentially connected from the rear. The drive gears 39a to 42a of the first to fourth speeds are freely fitted.
The first speed driving gear 39a and the second speed driving gear 40a are alternatively rotated integrally with the input shaft 37 by the first clutch means 43, and the third speed driving gear 41a and the fourth speed driving gear 42a are The two-clutch means 44 is alternatively rotated integrally with the input shaft 37.

The counter shaft 38 is provided with first to fourth speed driven gears 39b to 42b so as to be integrally rotatable. The driven gears 39b to 42b are driven from the first speed to the fourth speed driving gear 39a on the input shaft 37. ˜42a mesh with each other.
The first to fourth speed driven gears 39b to 42b on the counter shaft 38 are sequentially arranged from the front side to the rear side from the high speed side to the low speed side, and therefore the gear diameter gradually decreases from the rear side to the front side. The front-end fourth speed driven gear 42b has a minimum diameter.

The first clutch means 43 and the second clutch means 44 are of a synchromesh type, and are alternatively manually operated by one shift lever, and the main transmission mechanism 9 is moved from the neutral state to the first to fourth speeds. The speed can be changed to either speed.
A low-speed drive gear 46 for the subtransmission mechanism 10 is formed in the front portion of the fourth-diameter driven gear 42b having the smallest diameter of the counter shaft 38 (the highest speed driven gear). The third speed driven gear 41b (next high speed driven gear) is also used.

  The subtransmission mechanism 10 is provided between the counter shaft 38 and an output shaft 47 arranged in parallel therewith, and on the output shaft 47, a low-speed driven gear 48 that meshes with the low-speed drive gear 46, and a third speed. A high-speed driven gear 49 that meshes with the driven gear 41b is loosely fitted, and the low-speed driven gear 48 and the high-speed driven gear 49 are alternatively coupled to the output shaft 47 by the third clutch means 50 so as to be integrally rotatable.

Since the third speed driven gear 41b and the fourth speed driven gear 42b are smaller in diameter than the other driven gears 39b, 40b of the main transmission mechanism 9, the low speed driven gear 48 and the high speed driven gear 49 are the driven gears. 41b and 42b can be arranged so as to overlap in the axial direction.
That is, the front and rear positions and front and rear lengths of the low speed driven gear 48 and the high speed driven gear 49 are substantially the same as the front and rear positions and front and rear lengths of the low speed driving gear 46, the third speed driven gear 41b, and the fourth speed driven gear 42b. In addition, since the fourth speed driven gear 42b has a minimum diameter, even if the third clutch means 50 is disposed on the output shaft 47, it does not interfere. Conversely, the fourth speed driven gear 42b can be disposed between the low speed drive gear 46 and the third speed driven gear 41b corresponding to the third clutch means 50.

By providing the low-speed drive gear 46 on the front side of the fourth-speed driven gear 42b, the large-diameter low-speed driven gear 48 is arranged without interfering with the other driven gears 39b and 40b, and without creating a useless space around it. It is possible to do.
The output shaft 47 is supported by the second support wall Mb and the rear shaft support holder 28, the rear end is connected to the bevel pinion 51, and transmits rear wheel power to the rear wheel differential mechanism 11.

A front wheel power take-out gear 53 is mounted on the front end of the output shaft 47 adjacent to the front side of the low-speed driven gear 48. The front wheel power take-out gear 53 meshes with the lower transmission gear 54, and the front wheel power take-out means 52 is connected. It is composed.
The front wheel power take-out means 52 is provided between the front portion of the output shaft 47 and the rear portion of the front wheel power take-out shaft 55, and the transmission gear 54 is loosely fitted to the front wheel power take-out shaft 55, and front wheel drive clutch means. Free rotation and coupling are selected by 56 and coupled, whereby the power of the output shaft 47 is transmitted to the front wheel differential mechanism as front wheel power via the front wheel power take-out gear 53, the transmission gear 54, and the front wheel power take-out shaft 55. Communicated.

The front wheel power take-out shaft 55 is supported through the first support wall Ma at the front and rear intermediate portions, and the rear end supporting the transmission gear 54 is supported on the second support wall Mb on the rear side of the transmission gear 54, and is rotatable freely. It is supported by.
1 and 5, the output shaft 47 is arranged in parallel to the input shaft 37 and the counter shaft 38, and is arranged in a triangle with them. The propulsion shaft 6 and the PTO drive shaft 16 are concentric with the crankshaft of the engine E, and the front wheel power take-out shaft 55 is located in the center in the left-right direction of the transmission case M, and the output shaft 47 is on the left and right (right side). The input shaft 37 is shifted slightly to the left and right (right side).

The second support wall Mb is vertically separated into upper and lower wall parts Mb1 and Mb2, and the upper wall part Mb1 has a rear end of the propulsion shaft 6 and the reverse transmission shaft 29, an output shaft 47, a counter shaft 38, and an input shaft 37. The lower wall portion Mb2 supports the front wheel power take-out shaft 55.
The upper wall portion Mb1 and the lower wall portion Mb2 are separated from each other in order to dispose the front wheel power take-out gear 53 and the transmission gear 54 therebetween, and accordingly, the upper wall portion Mb1 and the lower wall portion Mb2 are separated from each other. An opening 57 that is open in the up-down direction and the front-rear direction is formed therebetween.

The opening 57 has a larger area than the case where the lower wall portion Mb <b> 2 is positioned forward and backward as compared with the case where the lower wall portion Mb <b> 2 is located immediately below the upper wall portion Mb <b> 1.
In the transmission case M, except for the first chamber 20, an oil bath is provided from the second chamber 21 to the sixth chamber 25, and oil for the transmission T and mission oil for the hydraulic actuator are stored.

The lower wall Mb2, the third support wall Mc, the fourth support wall Md, and the like are each formed with a passage 58 between the bottom of the transmission case M, and the transmission of the mission oil from the second chamber 21 to the sixth chamber 25. It is a road.
Since the upper wall portion Mb1 supports the front end of the output shaft 47 on the front side of the front wheel power take-out gear 53, the low speed driven gear 48, the high speed driven gear 49 and the front wheel power take-out gear 53 of the output shaft 47 are arranged. The front and rear portions of the portion are both supported by the upper wall portion Mb1 and the rear shaft support holder 28.

The lower wall portion Mb2 is located below the low-speed driven gear 48 and immediately below the front-rear direction, and enables the arrangement of the large-diameter low-speed driven gear 48. The low-speed driven gear 48 and the front wheel power take-out gear 53 are closely adjacent to each other. Is possible.
Further, by allowing the front wheel power take-out gear 53 to be arranged at the front end of the output shaft 47, the front and rear positions of the transmission gear 54 in the front mission case MF are made as far forward as possible, and the front wheel power take-out shaft 55 becomes the output shaft 47. Thus, the length of overlapping in the front-rear direction is shortened, and the front wheel power take-out shaft 55 can be formed short and inexpensively.

1 and 5, the rear end of the front mission case MF is largely open, and a plurality (four places) of protrusions 59 are provided on the inner peripheral surface in the vicinity of the rear part. The rear shaft support holder 28 is provided on the protrusions 59. The outer peripheral portion is held by a fastener such as a bolt.
1, 2, 4 and 5, on the front side of the rear shaft support holder 28, there are a bearing recess 28a for supporting the input shaft 37 via a bearing, and a bearing recess 28b for supporting the counter shaft 38 via a bearing. A bearing recess 28c that supports the output shaft 47 via a bearing is formed, a pump power take-out means 60 is provided on the back side, and a lubricating oil passage 28d is formed inside.

A hydraulic pump 61 for supplying hydraulic oil to the hydraulic equipment of the tractor is mounted on the outer surface of the side wall near the rear end of the front mission case MF, and the power is taken out from the PTO drive shaft 16 via the pump power take-out means 60. Yes.
The pump power take-out means 60 has a transmission bevel gear 62 fitted to the PTO drive shaft 16 and a take-out bevel pinion 63 meshed with the transmission bevel gear 62. The pinion holding portion 28f and the hydraulic pump 61 The pump shaft 61a is detachably connected via a coupling 66. The take-out bevel pinion 63 is integrally formed with the shaft portion and the bevel gear, but may be formed separately and fixed.

The rear shaft support holder 28 is formed with a gear holding portion 28e that supports the transmission bevel gear 62 via a bearing 64 and a pinion holding portion 28f that protrudes rearward and supports the take-out bevel pinion 63 via a bearing 65. The gear holding portion 28e and the pinion holding portion 28f are orthogonal to each other.
Accordingly, in the rear shaft support holder 28, the bearing recesses 28a, 28b and 28c are processed from the front side, the gear holding portion 28e is processed on the back side, and the lubricating oil passage 28d and the pinion holding portion 28f are processed from the outside. Since these are processed into one object, the centering can be accurately performed, and the meshing adjustment between the transmission bevel gear 62 and the extraction bevel pinion 63 can be easily and accurately performed.

  The rear end of the pinion holding portion 28f of the rear shaft support holder 28 and the rear end of the mounting portion 61b of the hydraulic pump 61 are located in front of the rear mission case MR mating surface 70 of the rear end of the front mission case MF, When the structures are assembled in the front and rear transmission cases MF and MR, respectively, the structures protruding from the mating surface 70 are reduced to facilitate assembly.

The rear shaft support holder 28 is inserted from the rear end of the front mission case MF and attached to the protrusion 59 on the inner surface of the front mission case MF. After the transmission bevel gear 62 and the take-out bevel pinion 63 are assembled, the hydraulic pump 61 is connected to the front mission case MF. Can be assembled from outside.
In the present invention, the shape of each member and the positional relationship between the front, back, left, and right in the above embodiment are best configured as shown in FIGS. However, it is not limited to the said embodiment, A member, a structure can be variously deformed, and a combination can also be changed.

For example, the first transmission mechanism is the hydraulic switching type forward / reverse switching mechanism 8, but it may be a hydraulic switching type high / low switching mechanism for switching the power of the propulsion shaft 6 or a manual switching type transmission mechanism. Good.
The second speed change mechanism is composed of the main speed change mechanism 9 and the sub speed change mechanism 10, but only the main speed change mechanism 9 may be used, and a super speed reduction mechanism for further decelerating is added to the main speed change mechanism 9 and the sub speed change mechanism 10. May be.

  The mission case M may be an integrated body without a mating surface between the previous mission case MF and the rear mission case MR.

DESCRIPTION OF SYMBOLS 1 Power take-out device 6 Propulsion shaft 7 PTO shaft 8 Forward / reverse switching mechanism 9 Main transmission mechanism 10 Sub transmission mechanism 16 Drive shaft 17 PTO transmission shaft 20 First chamber 21 Second chamber 22 Third chamber 27 Front shaft support holder 28 Rear shaft Support holder 28e Gear holding portion 28f Pinion holding portion 29 Reverse transmission shaft 36 Input gear 37 Input shaft 38 Counter shaft 47 Output shaft 60 Pump power take-out means 61 Hydraulic pump 62 Transmission bevel gear 63 Take-out bevel pinion F Flywheel housing M Mission case MF Front Mission case MR Rear mission case Ma First support wall Mb Second support wall T Transmission

Claims (4)

Inside the transmission case (M), a first transmission mechanism (8) for shifting the power of the propulsion shaft (6) and a second transmission mechanism for shifting the power from the first transmission mechanism (8) are provided. The PTO drive shaft (16) is directly connected coaxially to the rear portion of the propulsion shaft (6), and the PTO transmission shaft (17) is disposed behind the PTO drive shaft (16) via the PTO clutch (18). )
A rear shaft support holder (28) supporting the rear portion of the second transmission mechanism and penetrating the PTO drive shaft (16) is detachably mounted in the transmission case (M), and the rear shaft support holder (28) and Pump power take-out means (60) for transmitting the power of the PTO drive shaft (16) to the hydraulic pump (61) mounted on the outer surface of the transmission case (M) is provided between the PTO clutch (18) and
The pump power take-out means (60) includes a transmission bevel gear (62) mounted on the PTO drive shaft (16) and a pump shaft (61a) of the hydraulic pump (61) meshing with the transmission bevel gear (62). A take-out bevel pinion (63) that is detachably connected;
A gear holding part (28e) for supporting the transmission bevel gear (62) and a pinion holding part (28f) protruding rearward and supporting the take-out bevel pinion (63) are provided on the rear side of the rear shaft support holder (28). A power transmission device for a tractor, characterized by being provided. First and second support walls (Ma and Mb) are provided inside the front transmission case (MF) disposed between the flywheel housing (F) and the rear transmission case (MR), and the flywheel housing (F) A first chamber (20) communicating with the inside, a second chamber (21) in the middle portion, and a third chamber (22) in the rear portion are formed, and a back wall of the third chamber (22) is formed. The rear shaft support holder (28) is detachably mounted in the front mission case (MF),
As the first speed change mechanism (8), the propulsion shaft (6) is moved from the propulsion shaft (6) to the input shaft (37) or from the propulsion shaft (6) to the input shaft (37) via the reverse transmission shaft (29 ). A forward / reverse switching mechanism (8) that shifts and transmits power in the forward / reverse direction is disposed in the second chamber (21), and forward / reverse power is transmitted from the forward / reverse switching mechanism (8) as the second transmission mechanism. A multi-speed main transmission mechanism (9) between the input shaft (37) and the counter shaft (38), and a sub-transmission for transmitting rear wheel power by changing the height from the counter shaft (38) to the output shaft (47). The power transmission device for a tractor according to claim 1, wherein the mechanism (10) is arranged in the third chamber (22).   On the front side of the rear shaft support holder (28), bearing portions of the input shaft (37), counter shaft (38) and output shaft (47) are formed in a triangular arrangement, and the bearing portion of the counter shaft (38) is formed. The power transmission device for a tractor according to claim 2, wherein the gear holding portion (28e) is formed on the back side of the tractor.   The rear end of the pinion holding portion (28f) of the rear shaft support holder (28) and the rear end of the mounting portion of the hydraulic pump (61) are the rear transmission case (MR) mating surface of the rear end of the front mission case (MF) The power transmission device for a tractor according to claim 2 or 3, wherein the power transmission device is positioned in front of (70).

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