JP4916570B1 - Power transmission device for tractor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve fluidity of oil in front and rear of a support wall by separating a support wall supporting a transmission mechanism and a front wheel power take-off shaft vertically and forming an opening opened in the vertical direction and the front-rear direction therebetween. To do.
A forward / reverse switching mechanism 8 for shifting the power of a propulsion shaft 6 forward and backward is disposed in a second chamber 21, and a main transmission mechanism 9, a subtransmission mechanism 10 and an output shaft 47 are disposed in a third chamber 22. The front wheel power take-out shaft 55 that transmits the power of the output shaft 47 through the front wheel power take-out means 52 and takes out the front wheel power is supported by the first and second support walls Ma and Mb. The second support wall Mb is separately formed into an upper wall portion Mb1 that supports the first transmission mechanism 8 and the second transmission mechanisms 9 and 10, and a lower wall portion Mb2 that supports the front wheel power take-out shaft 55, and the upper wall portion. An opening 57 opened in the vertical direction and the front-rear direction is formed between Mb1 and the lower wall portion Mb2.
[Selection] Figure 1

Description

  The present invention relates to a power transmission device for a tractor having a front wheel power take-out shaft.

  In the prior art of the power transmission device for a tractor, as disclosed in Patent Document 1, first and second support walls are provided inside a mission case connected to the flywheel housing, The first chamber, the second chamber in the middle portion, and the third chamber in the rear portion are formed respectively, and the second chamber and the third chamber are oil baths, and the power of the propulsion shaft is changed in the second chamber. A plurality of speed change mechanisms of the traveling system are arranged, and a front wheel power take-out shaft for taking out power from the speed change mechanism to front wheel drive via front wheel power take-out means is supported on the second support wall that partitions the rear portion of the second chamber. ing.

  In Patent Document 2, a hydraulic switching type forward / reverse switching mechanism is provided in which first and second support walls are provided inside the front mission case of the front / rear transmission case, and the power of the propulsion shaft is shifted forward / backward in the second chamber. A main transmission mechanism that multi-shifts the power from the forward / reverse switching mechanism to the third chamber, a sub-transmission mechanism that shifts the power shifted by the main transmission mechanism, and a rear wheel power transmitted from the sub-transmission mechanism. An output shaft is disposed, and a front wheel power take-out shaft that takes out the power of the front wheel through the front wheel power take-out means is transmitted to the first and second support walls.

JP 2006-307955 A JP 2006-96108 A

  Both of the above prior arts are oil baths that communicate with the front and rear in the transmission case and are capable of oil flow, and the second support wall has an oil passage that communicates the second and third chambers. However, the second support wall not only supports the main transmission mechanism, the sub-transmission mechanism and the output shaft from the upper part to the lower part, but also supports the front wheel power extraction shaft at the lower part. The bearings and the transmission gears of the cylinder block the oil flow from the second chamber to the third chamber, causing an increase in the oil temperature. In particular, when a hydraulic switching type transmission mechanism is used, the amount of oil flowing out from the transmission mechanism is large, and therefore the fluidity of oil becomes a problem.

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 separates the support wall that supports the speed change mechanism and the front wheel power take-off shaft into upper and lower parts, and forms an opening that is open in the vertical direction and the front-rear direction therebetween, thereby improving the fluidity of oil before and after the support wall. It is an object of the present invention to provide a power transmission device for a tractor that can be improved.

Specific means for solving the problems in the present invention are as follows.
First, the first and second support walls Ma and Mb are provided inside the front transmission case MF connected to the flywheel housing F, the first chamber 20 communicating with the inside of the flywheel housing F, The second chamber 21 and the rear third chamber 22 are formed, and the second chamber 21 and the third chamber 22 are oil baths,
A forward / reverse switching mechanism 8 that shifts the power of the propulsion shaft 6 forward and backward is disposed in the second chamber 21, and the power transmitted from the forward / backward switching mechanism 8 to the input shaft 37 is shifted in multiple stages in the third chamber 22. The main transmission mechanism 9 that transmits to the counter shaft 38, the sub-transmission mechanism 10 that transmits the power shifted by the main transmission mechanism 9 from the counter shaft 38, and the output that transmits the rear wheel power from the sub-transmission mechanism 10. A tractor power transmission device in which a shaft 47 is disposed and a front wheel power take-out shaft 55 for taking out the front wheel power through the front wheel power take-out means 52 is supported by the first and second support walls Ma and Mb. There,
An upper wall portion Mb1 for rotatably supporting the second support wall Mb on the propulsion shaft 6 of the forward / reverse switching mechanism 8, the input shaft 37 of the main transmission mechanism 9, the counter shaft 38 and the output shaft 47 of the auxiliary transmission mechanism 10. And a lower wall portion Mb2 that is separated rearward and downward from the upper wall portion Mb1 and supports the front wheel power take-out shaft 55, and is formed in a vertical direction between the upper wall portion Mb1 and the lower wall portion Mb2. And an opening 57 opened in the front-rear direction is formed, and the front wheel power take-out means 52 is disposed in the opening 57,
The front wheel power take-out means 52 is engaged with the front wheel power take-out gear 53 disposed at the front end of the output shaft 47 on the rear side of the upper wall portion Mb1 and the front wheel power take-out gear 53 and possess a transmission gear 54 supported on the end,
The auxiliary low speed driven gear 48 of the auxiliary transmission mechanism 10 disposed adjacent to the front wheel power take-out gear 53 at the front end of the output shaft 47 is arranged above the lower wall portion Mb2, and the transmission gear 54 is connected to the front wheel power take-out shaft 55. It has a front wheel drive clutch means 56 coupled to and disposed below the upper wall portion Mb1 characterized Rukoto.

Second, in the front wheel power take-out means 52, the front wheel power take-out gear 53 projects downward from the upper wall portion Mb1 in the opening 57, and the transmission gear 54 projects from the lower wall portion Mb2 in the opening 57.
Wherein between the lower wall portion Mb2 the bottom of the front transmission case MF, characterized by forming the second chamber 21 and the oil passage 58 for communicating the third chamber 22.

According to the present invention, the fluidity of oil before and after the support wall that supports the speed change mechanism and the front wheel power take-out shaft can be improved.
That is, according to the first aspect of the present invention, the second support wall Mb that supports the speed change mechanism and the front wheel power take-off shaft is formed in the upper wall portion Mb1 and the lower wall portion Mb2 so as to be vertically separated, and the vertical direction and the front-rear direction therebetween. The front wheel power take-out means 52 is disposed in the opening 57, so that the fluidity of oil from the second chamber 21 to the third chamber 22 can be improved and the front wheel power take-out The arrangement of the means 52 can also be optimized.

In the invention according to claim 2, the front wheel power take-out means 52 includes a front wheel power take-out gear 53 at the front end of the output shaft 47 and at the rear side of the upper wall portion Mb1, and a front wheel power take-out shaft 55 at the front side of the lower wall portion Mb2. The rear transmission gear 54 can be meshed in the opening 57, and the arrangement of the front wheel power take-out means 52 can be optimized.
According to the third aspect of the present invention, the second support wall Mb for supporting the speed change mechanism and the front wheel power take-off shaft is vertically separated into the upper wall portion Mb1 and the lower wall portion Mb2, and opened in the vertical direction and the front-rear direction therebetween. Since the opening 57 is formed, the fluidity of oil from the second chamber 21 to the third chamber 22 can be improved, and an increase in the oil temperature can be suppressed.

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 take-out bevel pinion 63 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 traveling transmission mechanism is a hydraulic switching type forward / reverse switching mechanism 8, a main transmission mechanism 9, and a sub-transmission mechanism 10, but the forward / reverse switching mechanism 8 may be a manual switching type. Instead of this, a hydraulic switching type or manual switching type high / low switching mechanism for switching the power of the propulsion shaft 6 may be used.
The main transmission mechanism 9 and the sub-transmission mechanism 10 may be hydraulically switched or may not include the sub-transmission mechanism 10, and conversely, the super-deceleration mechanism that further decelerates the main transmission mechanism 9 and the sub-transmission mechanism 10. May be added.

  Further, the second chamber 21 is formed long in the front-rear direction, and a plurality of travel system speed change mechanisms such as the forward / reverse switching mechanism 8, the main speed change mechanism 9, and the sub-speed change mechanism 10 are disposed therein. A rear end of the front wheel power take-out shaft 55 is supported by a second support wall Mb that partitions the rear portion, and the front wheel power take-out shaft 55 is positioned below the substantially entire length in the front-rear direction of the plurality of traveling system transmission mechanisms. It may be a thing.

DESCRIPTION OF SYMBOLS 1 Power take-out device 6 Propulsion shaft 8 Forward / reverse switching mechanism 9 Main transmission mechanism 10 Sub transmission mechanism 11 Rear wheel differential mechanism 12 Front wheel power take-out mechanism 16 Drive shaft 20 First chamber 21 Second chamber 22 Third chamber 27 Front shaft support holder 28 Rear shaft support holder 29 Reverse transmission shaft 36 Input gear 37 Input shaft 38 Counter shaft 47 Output shaft 48 Sub-low speed driven gear 49 Sub-high speed driven gear 52 Front wheel power take-out means 53 Front wheel power take-out gear 54 Transmission gear 55 Front wheel power take-out shaft 56 Front wheel drive clutch means 57 Opening E Engine F Flywheel housing M Mission case MF Front mission case MR Rear mission case Ma First support wall Mb Second support wall Mb1 Upper wall portion Mb2 Lower wall portion T Transmission

Claims (2)

First and second support walls (Ma, Mb) are provided in the front transmission case (MF) connected to the flywheel housing (F) to communicate with the flywheel housing (F). ), An intermediate second chamber (21) and a rear third chamber (22), and the second chamber (21) and the third chamber (22) are oil baths,
A forward / reverse switching mechanism (8) for shifting the power of the propulsion shaft (6) forward and backward is disposed in the second chamber (21), and an input shaft (from the forward / reverse switching mechanism (8) to the third chamber (22). 37) a main transmission mechanism (9) that multi-shifts the power transmitted to 37) and transmits it to the countershaft (38), and transmits the power shifted by this main transmission mechanism (9) from the countershaft (38). A sub-transmission mechanism (10) for shifting gears and an output shaft (47) for transmitting rear wheel power from the sub-transmission mechanism (10) are arranged, and the power of the output shaft (47) is transmitted via the front wheel power take-out means (52). A power transmission device for a tractor in which a front wheel power take-off shaft (55) for taking out front wheel power is supported by first and second support walls (Ma, Mb),
The second support wall (Mb) is connected to the propulsion shaft (6) of the forward / reverse switching mechanism (8), the input shaft (37) of the main transmission mechanism (9), the counter shaft (38) of the auxiliary transmission mechanism (10), and An upper wall portion (Mb1) that rotatably supports the output shaft (47), and a lower wall portion (Mb2) that is separated rearward and downward from the upper wall portion (Mb1) and supports the front wheel power take-off shaft (55). And an opening (57) opened in the vertical direction and the front-rear direction is formed between the upper wall portion (Mb1) and the lower wall portion (Mb2), and the front wheel is formed in the opening (57). Power take-out means (52) is arranged,
The front wheel power take-out means (52) meshes with the front wheel power take-out gear (53) disposed at the front end of the output shaft (47) on the rear side of the upper wall portion (Mb1), and the front wheel power take-out gear (53). possess a supported transmission gear (54) to the rear end of the front wheel power take-axis (55) and has,
An auxiliary low-speed driven gear (48) of the auxiliary transmission mechanism (10) arranged adjacent to the front wheel power take-off gear (53) at the front end of the output shaft (47) is arranged above the lower wall portion (Mb2); power transmission device of a tractor, characterized that you have placed below the upper wall portion of the front wheel drive clutch means (56) for coupling to a transmission gear (54) front power take-axis (55) (Mb1). In the front wheel power take-out means (52), the front wheel power take-out gear (53) projects downward from the upper wall portion (Mb1) in the opening (57), and the transmission gear (54) falls in the lower wall portion in the opening (57). Projecting upward from (Mb2),
The lower wall portion (Mb2) forms an oil passage (58) communicating with the second chamber (21) and the third chamber (22) between the bottom portion of the front mission case (MF). The power transmission device for a tractor according to claim 1.

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