JP4390673B2 - Tractor transmission - Google Patents

Description

  The present invention relates to a transmission for a tractor.

Conventionally, in a tractor transmission, an output side of a main transmission that forms a plurality of shift stages so that the shift stage can be set to a high speed and a low speed while the speed of the tractor is set to one shift stage. A sub-transmission device that forms a high and low speed low range is provided, and in this type of transmission device, there is a gap between a counter shaft to which power from the engine is transmitted and a main transmission shaft arranged in parallel to the counter shaft. It is known that the main transmission is provided, and that the auxiliary transmission is provided between the main transmission shaft and the auxiliary transmission shaft arranged in parallel to the main transmission shaft.
For example, in the transmission of a tractor shown in Patent Document 1, the auxiliary transmission is arranged between a transmission output shaft on the output side of the main transmission and a travel shaft arranged in parallel to the transmission output shaft, and the transmission output shaft A low-speed input gear and a high-speed input gear are arranged in a rear portion so as to be rotatable integrally with the shift output shaft, and a low-speed output gear and a high-speed output gear are loosely fitted to the travel shaft so as to be relatively rotatable. The low-speed input gear meshes with the low-speed input gear, and the high-speed output gear meshes with the high-speed input gear.

Further, a clutch means for connecting the low-speed output gear and the traveling shaft or the high-speed output gear and the traveling shaft is arranged between the low-speed output gear and the high-speed output gear, and the low-speed output gear travels through the clutch means. The low speed range is selectively obtained by connecting to the shaft, and the high speed range is selectively obtained by connecting the traveling shaft to the high speed output gear via the clutch means.
JP 2001-30778 A

However, the sub-transmission of the above-described transmission has two high and low gears on the power input side and the power output side, respectively, and there is a problem that the number of parts increases and the device structure becomes complicated.
Therefore, in view of the above problems, the present invention provides a transmission for a tractor including a substructure having a simple structure in which the number of gears is reduced by using one gear of the main transmission. It is.

Specific means for solving the problems in the present invention are as follows.
First, a counter shaft, a main transmission shaft, and a sub transmission shaft are provided in parallel to each other, a main transmission is provided between the counter shaft and the main transmission shaft, and a sub transmission is provided between the main transmission shaft and the sub transmission shaft. Each equipped with a device,
The auxiliary transmission is provided on a main transmission shaft and meshes with one gear of the main transmission and a low-speed gear that rotates integrally with the main transmission shaft and is loosely fitted to the auxiliary transmission shaft so as to be relatively rotatable. A transmission gear, and a slide gear that is slidable in the axial direction on the auxiliary transmission shaft and is integrally rotatable, and is capable of meshing with the low-speed gear,
The slide gear is disengaged from the low-speed gear and engaged with the transmission gear so that the transmission gear can rotate integrally with the auxiliary transmission shaft.
An ultra-low speed gear that rotates integrally with the main transmission shaft is provided on the main transmission shaft, and a creep transmission device is provided between the ultra-low speed gear and the auxiliary transmission shaft. A creep first gear that meshes with the first gear and a creep second gear that is interlocked with the first creep gear, and a slide gear that is disengaged from the low-speed gear can be meshed with the second creep gear. .
A counter shaft, a main transmission shaft, and a sub transmission shaft are provided in parallel to each other, a main transmission device is provided between the counter shaft and the main transmission shaft, and a sub transmission device is provided between the main transmission shaft and the sub transmission shaft. Each has
The auxiliary transmission is provided on a main transmission shaft and meshes with one gear of the main transmission and a low-speed gear that rotates integrally with the main transmission shaft and is loosely fitted to the auxiliary transmission shaft so as to be relatively rotatable. A transmission gear, and a slide gear that is slidable in the axial direction on the auxiliary transmission shaft and is integrally rotatable, and is capable of meshing with the low-speed gear,
The slide gear is disengaged from the low-speed gear and engaged with the transmission gear so that the transmission gear can rotate integrally with the auxiliary transmission shaft.
The sub-transmission device is engaged with a gear different from the one gear of the main transmission and is freely fitted to the sub-transmission shaft, and the sub-speed gear is engaged when the slide gear is in a neutral position. And a clutch member coupled to the auxiliary transmission shaft.
Further, a counter shaft, a main transmission shaft and a transmission sub shaft are provided in parallel to each other, a main transmission device is provided between the counter shaft and the main transmission shaft, and a sub transmission device is provided between the main transmission shaft and the sub transmission shaft. Each has
The auxiliary transmission includes a low speed gear provided on a main transmission shaft and rotating integrally with the main transmission shaft, and a slide gear provided on the auxiliary transmission shaft so as to be slidable in the axial direction and meshable with the low speed gear. And
The slide gear is configured to be able to be interlocked with one gear of the main transmission on the main transmission shaft by releasing the meshing with the low speed gear.

According to this, the sub-transmission device forms a low-speed range by engaging the slide gear with the low-speed gear, releases the engagement between the slide gear and the low-speed gear, and slides the slide gear in the axial direction to perform the main transmission. A high speed range is formed by interlocking with the one gear of the apparatus. That is, one gear of the main transmission is also used as a high-speed input side gear of the sub-transmission, and a slide gear is also used as an output side of the high speed range and the low speed range.
Secondly, the slide gear is adapted to increase the speed of the auxiliary transmission shaft by interlocking with the one gear of the main transmission.

According to this, a speed increasing range is formed in the auxiliary transmission, the speed setting area of the auxiliary transmission is expanded, and the auxiliary transmission can be given substantially the same rotational speed as the engine.
Third, the sub-transmission device includes a transmission gear that meshes with the second-speed gear of the main transmission device and that is loosely fitted to the sub-transmission shaft, and the slide gear is detachably engageable with the transmission gear. It is a point to engage.
According to this, by sliding the slide gear on the auxiliary transmission shaft in the axial direction and engaging the transmission gear, the slide gear is interlocked with the one gear of the main transmission. Therefore, the high speed range of the auxiliary transmission is formed by the transmission gear and the slide gear, and it is not necessary to form a gear to be meshed with the one gear on the slide gear, and the configuration of the slide gear becomes simple. Thus, the increase in cost of the slide gear is suppressed.

Further, as the one gear of the main transmission, a gear train of each gear can be selected. However, when the gears of the third and fourth gear trains are selected, the gear diameter of the transmission gear is large. And cost increases. Further, when the gear of the first speed gear train is selected, when the distance between the main transmission shaft and the auxiliary transmission shaft is made as small as possible, the distance between the gear tip and the auxiliary transmission shaft is small. Therefore, a transmission gear cannot be provided between them. In view of both of these points, the transmission gear is engaged with the second-speed gear.
Fourth, an ultra-low speed gear that rotates integrally with the main transmission shaft is provided on the main transmission shaft, and a creep transmission device is provided between the ultra-low speed gear and the auxiliary transmission shaft. A creep first gear meshing with the ultra-low speed gear and a creep second gear interlocking with the creep first gear, and a slide gear that is disengaged from the low-speed gear can be meshed with the creep second gear. There is a point.

According to this, since the slide gear meshing with the low speed gear is meshed with the creep second gear of the creep transmission device, the slide gear is also used, and thereby the number of gears of the gear train to form the creep range is increased. Reduction is planned.
Further, by sliding the slide gear in the axial direction of the sub-transmission shaft and meshing with the creep second gear of the creep transmission device, the power input to the main transmission shaft becomes the creep speed of the ultra-low speed gear and the creep transmission device. It is output to the auxiliary transmission shaft through one gear, a creep second gear and a slide gear. Therefore, even when the creep range is set, the power output from the main transmission shaft is output to the auxiliary transmission shaft via the slide gear without passing through other shafts, thus simplifying the power transmission path. It is done.

Fifth, the creep transmission device includes a casing that rotatably supports the first and second gears, and the casing is detachably inserted from the outside of the transmission case.
According to this, since the creep transmission is formed as an assembly and is detachable from the transmission case incorporating the transmission, the deployment or non-deployment of the creep range is selected according to the use of the vehicle body or the user's request It becomes possible. In addition, a creep range deployment vehicle body and a non-deployment vehicle body can be the same model.

In addition, the creep transmission device is arranged in the sub-transmission device when the creep first gear meshes with the ultra-low speed gear on the main transmission shaft and the creep second gear meshes with the slide gear. The only gear in the mission case that is not required when not deployed is the ultra-low speed gear, and the unnecessary components that are not deployed in the creep transmission are greatly reduced.
Sixth, the sub-transmission device engages with a gear different from the one gear of the main transmission unit and is freely fitted to the sub-transmission shaft, and the slide gear is in the neutral position. And a clutch member for connecting the different speed gear to the auxiliary transmission shaft.

According to this, the auxiliary transmission is provided with a different speed range, and the speed range of the vehicle body is increased.
Seventh, a shuttle transmission that provides a propulsion shaft that is linked to the engine in front of an extension line of the main transmission shaft, and that provides forward or reverse power to the main transmission between the propulsion shaft and the countershaft. The shuttle transmission is at least a point where the forward power is decelerated and transmitted to the counter shaft.
According to this, the normal rotation power to be input to the main transmission is decelerated and input to the counter shaft. For this reason, when giving the same reduction gear ratio to the power output to the main transmission shaft via the main transmission as in the prior art, the gear diameter of the gear of the main transmission can be reduced. The distance between the shaft and the main transmission shaft can be reduced.

Eighth, the main transmission includes a gear train that decelerates the power transmitted from the shuttle transmission and transmits it to the main transmission shaft, and the main transmission shaft that increases the power transmitted from the shuttle transmission. And a gear train that is transmitted.
According to this, the power input to the main transmission is decelerated to a predetermined reduction ratio and output to the main transmission shaft, as well as being increased to a speed substantially the same as that of the engine. It can also be output to the transmission shaft.

  According to the tractor transmission of the present invention, it is possible to provide a sub-transmission having a simple structure with a reduced number of gears by sharing one gear of the main transmission.

Hereinafter, embodiments of the present invention applied to a tractor will be described with reference to the drawings.
As shown in FIG. 11, the tractor 1 embodying the present invention is a two-shaft, four-wheel type having a pair of left and right front wheels 2 and a rear wheel 3, and an engine 4 as a driving source of the tractor 1 is provided at the front of the body. A mission case 5 constituting the vehicle body 1 a of the tractor 1 is provided at the rear of the engine 4. The transmission case 5 includes a transmission 8 including a traveling mission 6 and a PTO mission 7 shown in FIGS. 1 and 2.
Further, as shown in FIG. 11, a pair of left and right fenders 9 covering the inner side and the bottom surface of the rear wheel 3 from the front part to the upper part are arranged on the left and right sides of the central part of the mission case 5. A driver's seat 10 is provided between the pair of left and right fenders 9, and a steering handle 11 is provided in front of the driver's seat 10. The driver's seat 10 and the steering handle 11 are surrounded by a cabin 12 that is detachably mounted on the vehicle body 1a.

Further, on the rear upper surface of the transmission case 5, a hydraulic lifting / lowering device 14 including left and right lift arms 13 and a link mounting body 15 indicated by a three-point link is arranged, and the work illustrated in the figure as a rotary tiller A machine 16 is mounted via the link mounting body 15. Further, the working machine 16 is transmitted with power from the engine 4 via a PTO shaft 31 described later that extends from the inside of the transmission case 5 to the rear of the vehicle body 1a.
As shown in FIG. 2, the mission case 5 is formed by connecting a front mission case 18 provided at the rear part of the engine 4 and a rear mission case 19 provided at the rear part of the front mission case 18. .

As shown in FIGS. 1 and 2, the traveling system mission 6 includes a propulsion shaft 21, a counter shaft 22, a main transmission shaft 23, and a sub transmission shaft 24 in parallel with each other. A shuttle transmission 25 is provided between the shafts 22, a main transmission 26 is provided between the counter shaft 22 and the main transmission shaft 23, and an auxiliary transmission 27 is provided between the main transmission shaft 23 and the auxiliary transmission shaft 24. Has been deployed.
The PTO transmission 7 includes a PTO input shaft 29, a PTO transmission shaft 30, a PTO relay shaft 30 a, and a PTO shaft 31 that are parallel to each other, and is located between the PTO input shaft 29 and the PTO transmission shaft 30. A PTO clutch 32 is provided, the PTO transmission shaft 30 and the PTO relay shaft 30 a are connected to each other, and a PTO speed reducer 33 is provided between the PTO relay shaft 30 a and the PTO shaft 31.

Further, the front transmission case 18 is divided forward and backward by an intermediate wall 34, a shuttle transmission 25 is provided on the front side, and a main transmission 26 and an auxiliary transmission 27 are provided on the rear side. Further, the front of the shuttle transmission 25 is closed by a front cover 35 that is detachably attached to the front mission case 18.
As shown in FIGS. 2 and 3, in the traveling system mission 6, the propulsion shaft 21 extends through the front cover 35 to the front of the transmission case 5, and the tip of the propulsion shaft 21 passes through the buffer spring 36 to -It is connected to the flywheel 37. Further, a cylindrical main transmission shaft 23 is provided on the rear side of the extension line of the propulsion shaft 21, and the main transmission shaft 23 and the counter shaft 22 extended along the propulsion shaft 21 are shown in FIG. As described above, the main transmission shaft 23 and the propulsion shaft 21 are disposed on the lower side.

The shuttle transmission device 25 is a device for switching between forward rotation (forward) and reverse rotation (reverse) of the power transmitted from the engine 4 via the propulsion shaft 21 and outputting it to the counter shaft 22. In the embodiment, a hydraulic type is adopted.
As shown in FIG. 3, the shuttle transmission 25 includes a clutch body 40 that is concentrically fixed to the propulsion shaft 21, and the front and rear that are loosely fitted concentrically to the propulsion shaft 21 inside the clutch body 40. A pair of inner cylinders 41f and 41r, forward and reverse clutch members 42f and 42r interposed between the clutch body 40 and the inner cylinders 41f and 41r, and the propulsion inside the clutch body 40 A pair of front and rear pistons 43f and 43r provided slidably in the axial direction of the shaft 21 is provided.

  The clutch body 40 has a fixed sleeve portion 40a fixed to the outer peripheral surface of the propulsion shaft 21 through a key so as not to be relatively rotatable, a central wall portion 40b projecting radially outward from the outer peripheral surface center of the fixed sleeve 40a, An outer sleeve portion 40c extending in parallel with the propulsion shaft 21 is integrally provided at an outer edge portion of the central wall portion 40b. Of the pair of front and rear spaces between the fixed sleeve portion 40a and the outer sleeve portion 40c, the space on the front cover 35 side is opened forward, and the clutch support portion 44r of the inner cylinder 41r for reverse rotation is accommodated in this space. Has been. Also, the space on the main transmission shaft 23 side is opened rearward, and the clutch support portion 44f of the inner cylinder 41f for normal rotation is accommodated in the space.

  The pair of front and rear pistons 43f and 43r are connected to the central wall 40b in a pair of front and rear storage chambers 45f and 45r formed by the clutch members 42f and 42r, the inner cylinders 41f and 41r, and the central wall 40b of the clutch body 40. They are housed in a state where the back surfaces face each other, and are in sliding contact with the outer peripheral surface of the fixed sleeve 40a and the inner peripheral surface of the outer sleeve 40c in an oil-tight state via a seal ring. Further, return springs for returning the pistons 43f and 43r to the non-operating position are provided in the clutch support portions 44f and 44r of the inner cylinders 41f and 41r.

  A pair of hydraulic fluid passages 47f and 47r are formed in the propulsion shaft 21 and the fixed sleeve 40a of the clutch body 40, and one hydraulic fluid passage 47f is on the piston back side of the forward rotation side storage chamber 45f. The other hydraulic oil passage 47r is communicated with the piston back surface side of the reverse containing chamber 45r. When hydraulic oil from an oil valve (not shown) is supplied to the pair of hydraulic oil passages 47f and 47r, either one of the pair of front and rear pistons is selectively operated, and the piston and the clutch member are interposed. By connecting the inner cylinder to the clutch body 40, the inner cylinder rotates together with the clutch body 40.

The forward rotation inner cylinder 41f is formed with a forward transmission gear 48f on the outer peripheral surface behind the clutch support portion 44f. The forward transmission gear 48f is fixed to the counter shaft 22. Meshed with the forward rotation gear 49f.
Further, a reverse transmission gear 48r is formed on the outer peripheral surface in front of the clutch support portion 44f in the reverse inner cylinder 41r. The reverse transmission gear 48r is connected to the back idler gear 50 as shown in FIG. The back idler gear 50 is meshed with a reverse gear 49 r fixed to the counter shaft 22.

Here, as shown in FIG. 3, the gear diameters of the forward rotation gear 49f and the reverse rotation gear 49r are larger than the gear diameters of the forward rotation transmission gear 48f and the reverse rotation transmission gear 48r, respectively. For this reason, the power output to the counter shaft 22 via the normal rotation gear train including the normal rotation transmission gear 48f and the normal rotation gear 49f is decelerated from the power input to the shuttle transmission 25.
Similarly, the power output to the counter shaft 22 via the reverse gear train including the reverse transmission gear 48r, the back idler gear 50, and the reverse gear 49r is similarly decelerated from the power input to the shuttle transmission 25. is there.

As shown in FIG. 3, the back idler gear 50 is loosely fitted via a bearing to a reverse shaft 50a supported by the front cover 35 and arranged in parallel to the propulsion shaft 21, and the reverse gear 49r is a counter gear. It is supported by the front cover 35 via the shaft 22 and a bearing. The propulsion shaft 21 and the counter shaft 22 are supported by a front cover 35 and an intermediate wall 34 via bearings, and the main transmission shaft 23 is supported by a bearing on the intermediate wall 34 and the rear wall portion of the front transmission case 18. Is supported through.
Accordingly, by removing the front cover 35, the propulsion shaft 21, the back idler gear 50, and the reverse gear 49b can be detached from the front opening of the front mission case 18, and by removing these, the shuttle transmission 25 can be As a result, the shuttle transmission device 25 can be easily maintained without disassembling the entire transmission case 5.

  As shown in FIGS. 2 and 3, the main transmission 26 has four gear trains and gives four gears on the output side. The third gear train extends from the front to the rear. , A fourth speed gear train, a first speed gear train, and a second speed gear train are provided, and the counter shaft 22 includes input gears 51a to 51d of the gear trains via bearings. The main transmission shaft 23 is meshed with the input gears 51a to 51d corresponding to the output gears 52a to 52d. The main transmission shaft 23 is fixed to the main transmission shaft 23 so as to rotate integrally therewith.

A third / fourth speed switching clutch 53a is arranged between the third speed input gear 51c and the fourth speed input gear 51d. The third / fourth speed switching clutch 53a is configured as a synchronous occlusal clutch, and has a hub 54 fixed to the counter shaft 22 and an outer fitting to the hub 54 so as to be movable in the axial direction of the counter shaft 22. The hub 54 is provided with a synchronizing ring protruding from the hub 54 toward the third speed input gear 51c and the fourth speed input gear 51d.
Further, the third speed input gear 51c and the fourth speed input gear 51d are respectively provided with occlusal portions 56c and 56d to be engaged with the shifter 55 at positions facing the synchronization ring.

For example, in the third and fourth speed switching clutch, when the shifter 55 is moved in the axial direction of the counter 22 and engaged with the occlusal portion 56a of the third speed input gear 51a, the third speed input gear 51c is As a result, the power input to the counter shaft 22 is transmitted as the third speed power to the main transmission shaft 23 via the third speed gear train. The same applies when the fourth speed is set.
Further, a first / second speed switching clutch 53b is provided between the second speed input gear 51b and the first speed input gear 51a, and the first / second speed switching clutch 53b is provided with the first speed input gear 51b. The third and fourth speed switching clutch 53a has the same configuration, and includes a hub 54 fixed to the counter shaft 22 and a shifter 55 that is externally fitted to the hub 54 so as to be movable in the axial direction of the counter shaft 22. The hub 54 is provided with a synchronizing ring protruding toward the second speed input gear 51b and the first speed input gear 51a. Further, the second speed input gear 51b and the first speed input gear 51a are provided with projecting portions 56a and 56b to be engaged with the shifter 55 at positions facing the synchronization ring.

The switching clutch is shown as a key type inertia lock type in the present embodiment, but it may be a pin type inertia lock type, a constant load type, or a servo type. I do not care.
The power output from the shuttle transmission device 25 is transmitted to the main transmission shaft 23 by being shifted to a predetermined gear position via the main transmission device 26.
In the third speed gear train, the gear diameters of the third speed input gear 51c and the third speed output gear 52c are set to 1: 1, so that the third speed input gear 51c to the third speed output gear 52c are set. The power passing through is output to the main transmission shaft 23 at a constant speed.

In the first and second gear trains, the gear diameters of the output gears 52a and 52b are larger than those of the input gears 51a and 51b. Therefore, the power from the input gears 51a and 51b is transmitted to the output gears 52a and 52b. To slow down. As a result, the deceleration power is further decelerated and output to the main transmission shaft 23.
Here, conventionally, the power to be reduced to a predetermined reduction ratio by the main transmission is once reduced by the forward gear train or the reverse gear train before being input to the main transmission 26. For this reason, each gear to form the gear train of the main transmission 26 has a smaller diameter than the conventional gear when the predetermined reduction ratio is configured. The distance between the axes 23 is made shorter than before.

On the other hand, in the fourth speed gear train, the gear diameter of the fourth speed output gear 52d is smaller than that of the fourth speed input gear 51d, so that the power from the fourth speed input gear 51d is transferred to the fourth speed output gear 52d. The speed is increased by being transmitted. As a result, the decelerating power returns to the power speed before being decelerated by the forward and reverse gear trains (substantially the same speed as the propulsion shaft), and is then transmitted to the main transmission shaft 23.
Further, since the distance between the shafts is shortened as described above, even among the input gears 51a to 51d, even the fourth speed input gear 51d having the maximum gear diameter is larger than the forward rotation gear 49f. Therefore, the amount of protrusion of the input gear train of the main transmission 26 from the counter shaft 22 is small, and the distance between the inner surface of the mission case 5 and the counter shaft 22 is shortened, and the mission case is reduced. 5 can be miniaturized.

The auxiliary transmission 27 shown in FIG. 4 gives high and low gears to the power transmitted from the main transmission 26 and outputs it to the output side. The auxiliary transmission 27 is provided on the main transmission shaft 23 and is provided on the main transmission shaft. A low-speed gear 60 that rotates integrally with the transmission 23, a transmission gear 61 that is loosely fitted on the auxiliary transmission shaft 24 so as to be relatively rotatable coaxially and meshed with the second-speed output gear 52b of the main transmission 26, and an auxiliary transmission A slide gear 62 that rotates integrally with the shaft 24 and slides on the auxiliary transmission shaft 24 in the axial direction is provided.
The low speed gear 60 protrudes from the second speed output gear 52b, which is the last row of the main transmission 26, at a position spaced apart from the second speed output gear 52b, and the transmission gear 61 is idled to the auxiliary transmission shaft 24 via a bearing. The transmission gear 61 is formed with an engagement piece 63 that protrudes rearward.

The slide gear 62 is disposed on the rear side of the transmission gear 61 and includes an engaged piece 64 to be engaged with the engaging piece 63 at the front.
Of the second speed output gear 51b and the low speed gear 60 on the input side of the auxiliary transmission 27, the gear diameter of the low speed gear 60 is smaller than that of the second speed output gear 51b and is on the output side of the auxiliary transmission 27. Of the slide gear 62 and the transmission gear 61, the gear diameter of the transmission gear 61 is smaller than that of the slide gear 62 and smaller than that of the second speed output gear 51b.
In the auxiliary transmission device 27, a low-speed gear train is formed by sliding the slide gear 62 in the axial direction of the auxiliary transmission shaft 24 and meshing with the low-speed gear 60. The generated power is decelerated through the low speed gear 60 and the slide gear 62 and output.

Further, the engagement between the slide gear 62 and the low speed gear 60 is released, the slide gear 62 is slid in the axial direction, and the engaged piece 64 of the slide gear 62 is engaged with the engaging piece 63 of the transmission gear 61. As a result, the transmission gear 63 rotates together with the auxiliary transmission shaft 24 together with the slide gear 62, thereby forming a high-speed range gear train composed of the output gear 51 b and the transmission gear 61. In the high speed range, the power input from the second speed output gear 51 b is increased by passing through the transmission gear 61.
Here, as the gear of the main transmission 26 to be engaged with the transmission gear 61, any one of the output gears 52a to 52d of the gear train of each shift stage can be selected, but the third and fourth speed output gears 52c. , 52d, the gear diameter of the transmission gear 61 becomes large and the cost increases. Further, when the distance between the main transmission shaft 23 and the auxiliary transmission shaft 24 is made as small as possible as in the present embodiment, the distance between the tooth tip of the first speed output gear 52a and the auxiliary transmission shaft 24. Becomes so small that no gear can be deployed between them. In view of both of these points, the transmission gear 61 is meshed with the second speed output gear 52b.

Further, as shown in FIGS. 2 and 5, a creep transmission device 70 that transmits ultra-low speed (creep speed) power can be detachably attached to the output side of the auxiliary transmission device 27. An ultra-low speed gear 65 for transmitting power to the device 70 is provided behind the low speed gear 60 of the main transmission shaft 23 so as to be integrally rotatable with the main transmission shaft 23.
The creep transmission device 70 is of a cassette type that is inserted through the opening of the mission case 5 and is equipped with a casing 71 that is to be inserted into and supported by the mission case 5.

  Inside the casing 71, a pair of shaft bodies 72, 73 that should be arranged in parallel with the auxiliary transmission shaft 24 with the creep transmission device 70 mounted on the transmission case 5 are supported by the casing 71. A cylindrical body 74 is loosely fitted to the body 72, and a creep first gear 75 to be engaged with the ultra-low speed gear 65 is provided on the outer peripheral surface of the cylindrical body 74, and the creep first gear is provided. A creep relay gear 76 having a gear diameter smaller than 75 is projected. A creep second gear 77 that meshes with the creep relay gear 76 is fixed to the other shaft body 73.

As shown in FIGS. 5 and 7, by attaching the casing 71 of the creep transmission device 70 to the transmission case 5, the first creep gear 75 meshes with the ultra-low speed gear 65 of the auxiliary transmission device 27. The device 70 is provided in the auxiliary transmission device 27.
The slide gear 62 is slid in the axial direction of the auxiliary transmission shaft 24 and meshed with the creep second gear 77, thereby forming a gear train of a creep range (creep speed) via the creep transmission device 70. It is. That is, the power input from the main transmission 26 to the main transmission shaft 23 is transmitted to the creep first gear 75 of the creep transmission 70 via the ultra-low speed gear 65, and the creep relay gear 76, the creep second gear 77 and the like. This is output to the auxiliary transmission shaft 24 via the slide gear 62.

In addition, as shown in FIG. 2, the auxiliary transmission device 27 can include a medium speed gear (different speed gear) 78 that outputs a medium speed on the output side. The medium speed gear 78 is loosely fitted coaxially with the auxiliary transmission shaft 24 in front of the transmission gear 61 so as to be relatively rotatable, and meshes with the fourth speed output gear 51d of the main transmission 26. ing.
In addition, a clutch member 79 that connects and disconnects the intermediate speed gear 78 to the auxiliary transmission shaft 24 is disposed on the back of the intermediate speed gear 78. The clutch member 79 has substantially the same configuration as the switching clutch of the main transmission 26.

The clutch member 79 is in an interlocking state with the slide gear 62, and when the slide gear 62 is set in mesh with the low speed gear 60 or the creep second gear 77 of the creep transmission device 70, or with the transmission gear 61. When in the engaged state, the shifter of the clutch member 79 does not move, and the medium speed gear 78 is not connected to the auxiliary transmission shaft 24 so as to rotate integrally with the auxiliary transmission shaft 24.
When the slide gear 62 is set to a neutral state (neutral state) that does not link with any gear, the medium speed gear 78 is connected to the auxiliary transmission shaft through the shifter of the clutch member 79. As a result, a medium speed range is formed in the auxiliary transmission 27, and the power input to the main transmission shaft 26 is output as a medium speed via a medium speed gear train composed of the fourth speed output gear 52d and the medium speed gear 78. It is done.

Note that the slide gear 62 is positioned in a state that is not interlocked with any gear between the transmission gear 61 and the low-speed gear 60 and between the low-speed gear 60 and the super-low-speed gear 65, as indicated by a two-dot chain line in FIG. By doing so, the neutral state is set.
Further, the auxiliary transmission shaft 24 extends to the front portion of the rear transmission case 19 and is connected to the drive shaft 81 of the rear wheel differential device 80 via a coupling.
The traveling system mission 6 has the above-described configuration, and the power from the engine 4 is transmitted to the rear wheel differential device 80 after being shifted forward and backward in 16 stages. The left and right rear wheels 3 are driven from the left and right yoke shafts via the final reduction gear.

As shown in FIG. 1, the auxiliary transmission shaft 24 is supported by the intermediate wall 34 and the rear wall portion of the front transmission case 18 via bearings, and the front end portion of the auxiliary transmission shaft 24 is It passes through the intermediate wall 34 and protrudes toward the shuttle transmission in the mission case 5.
As shown in FIG. 6, a front wheel propeller shaft 82 is disposed below the shuttle transmission device 25 in parallel with the propulsion shaft 21 on the shuttle transmission device side in the transmission case 5. A front wheel moving shaft 84 is disposed behind the extension line via a shifter 83.

A front wheel drive gear train 85 that transmits power to the front wheel propeller shaft 82 is disposed between the front wheel take-up shaft 84 and the front end portion of the auxiliary transmission shaft 24. The front wheel moving gear 86 rotates integrally with the transmission shaft 24, and the front wheel transmission gear 87 meshes with the front wheel moving gear 86 and rotates together with the front wheel moving shaft 84.
The shifter 83 connects and disconnects the front wheel moving shaft 84 and the front wheel propeller shaft 82, and the shifter 83 is operated to connect the front wheel propeller shaft 82 to the front wheel moving shaft 84. The power from 24 is transmitted to the front wheel propeller shaft 82 via the front wheel drive gear train 85, whereby the vehicle body 1a is set to a four-wheel drive type in which the front wheels 2 are driven in synchronization with the rear wheels 3.

Further, by operating the shifter 83 to release the connection between the front wheel take-up shaft 84 and the front wheel propeller shaft 82, the power from the auxiliary transmission shaft 24 is not transmitted to the front wheel propeller shaft 82. 1a is set to a two-wheel drive type in which only the rear wheel 3 is driven.
As shown in FIGS. 1 and 2, in the PTO transmission 7, the PTO input shaft 29 is fitted into the cylindrical main transmission shaft 23, and its front end portion is rotated together with the propulsion shaft 21. Is fitted to the rear end of the propulsion shaft 21. The PTO transmission shaft 30 is arranged behind the PTO input shaft 29 via a PTO clutch 32, and a PTO relay shaft 30a is provided behind the PTO transmission shaft 30 via a coupling. It is connected. The PTO shaft 31 is arranged in parallel to the PTO relay shaft 30a, and is connected to the PTO relay shaft 30a via the PTO speed reducer 33.

As shown in FIGS. 7 and 8, a mounting portion 19a for mounting a shifter device (not shown) of the transmission 8 is provided on the right side portion of the rear transmission case 19 from the middle in the vertical direction to the lower portion. The case 19 is formed so as to project outward.
In addition, a pump support portion 91 for attaching the hydraulic pump 90 is formed at the upper portion of the attachment portion 19a. As shown in FIGS. 8 and 10, the pump support portion 91 is provided so as to protrude from the rear mission case 19 toward the fender 9 on the right rear wheel side. In this embodiment, the pump support portion 91 is integrated with the rear mission case 19. Thus, an increase in cost of the mission case 5 is suppressed.

The hydraulic pump 90 is a pump for system pressure, for the hydraulic elevator, for power steering, etc. As shown in FIGS. 9 and 10, a pump shaft 92 that transmits power to the gear pump inside the hydraulic pump 90 protrudes. The pump shaft 92 is supported by the rear transmission case 19 via the pump support portion 91 in a state in which the pump shaft 92 is parallel to the PTO input shaft 29 of the PTO transmission 7.
As a result, as shown in FIG. 8, the hydraulic pump 90 has a concave space surrounded by the right side wall portion forming the right side portion of the rear mission case 19, the fender 9 on the right rear wheel side, and the upper portion of the mounting portion 19a. Therefore, the hydraulic pump 90 does not protrude from the upper part of the mission case 5, and the space is effectively used.

The pump support portion 91 includes a mounting surface 91a for attaching the hydraulic pump 90 on the back surface, and an opening portion 91b through which the pump shaft 92 is inserted toward the inside of the pump support portion 91 is formed on the back surface 91a. ing.
As shown in FIG. 9, between the PTO input shaft 29 and the pump shaft 92, a pump power transmission mechanism 93 that transmits power to the hydraulic pump 90 extends over the inside of the pump support portion 91 and the inside of the rear transmission case 19. The pump power transmission mechanism 93 is provided with a pump drive gear 94 fixed to the PTO input shaft 29, a pump relay gear 95 loosely fitted on a shaft supported by the rear mission case 19, and a pump A pump transmission gear 96 that is externally fitted to the pump shaft 92 inserted in the support portion 91 so as to be integrally rotatable is meshed with the pump drive gear 94 and the pump relay gear 95, and the pump relay gear 95 and the pump transmission. The gear 96 is engaged with the gear 96, whereby the power from the PTO input shaft 29 is transmitted to the hydraulic pump 90.

Here, as shown in FIG. 8, the pump relay gear 95 and the shaft body that loosely supports the pump relay gear 95 are connected to the space between the counter shaft 22 and the PTO clutch 32 in the rear transmission case 19. The pump relay gear 95 is rotatably accommodated in the space, and the pump power transmission mechanism 93 is disposed in the left-right direction with respect to the axis of the PTO input shaft 29. The hydraulic pump 90 can be provided on the upper portion of the mounting portion 19a without increasing the size of the case 5.
The rotation region of the pump relay gear 95 includes the rotation region of the fourth speed input gear 51d having the maximum rotation radius on the counter shaft 22 and the first speed having the maximum rotation radius on the main transmission shaft 23. The rear transmission case 19 does not protrude greatly from the rotation region of the output gear 50d, and the rear transmission case 19 is not enlarged by disposing the pump relay gear 95 in the space.

Further, as shown in FIG. 9, the opening 91b of the pump support 91 has such a size that the pump transmission gear 96 and the bearing of the pump transmission gear 96 can be inserted into the inside from the outside of the pump support. Is formed. Moreover, the outer diameter of the bearing 97 made of a bearing material provided between the pump transmission gear 96 and the hydraulic pump 90 is the same as or slightly larger than the outer diameter of the pump transmission gear 96. The pump transmission gear 96 can be removed through the opening 91b.
Therefore, the pump transmission gear 96 and the bearings of the pump transmission gear 96 can be exchanged without disassembling the transmission case 5, and maintenance can be easily performed.

The embodiment in which the present invention is applied to a tractor has the above-described configuration. According to the tractor 1 of the present embodiment, the main transmission 26 can be downsized by inputting deceleration power to the main transmission 26. As a result, the mission case 5 can be reduced in size. Further, the deceleration power can be made substantially the same as the speed of the engine 4 by the fourth gear train of the main transmission 26.
In the mission case 5, the shuttle transmission 25 is provided in a chamber in front of the intermediate wall 34 opened toward the engine 4, and in a chamber behind the intermediate wall 34 opened in the rear mission case 19. Since the main transmission 26 and the sub transmission 27 are provided, the shuttle transmission 25 is removed from the front of the front transmission case 18 with the front cover 34 removed, and the main transmission 26 and the sub transmission 27 are connected to the front transmission case. Assembling / disassembling and maintenance can be performed separately from the rear portion of 18.

Further, since the front wheel moving shaft 84, the front wheel propeller shaft 82, the front wheel moving gear train 85 and the shifter 83 are arranged in the front chamber, a front wheel moving gear case for four-wheel drive is provided below the transmission case 5. This eliminates the need for mounting, reduces the number of parts and simplifies the assembly process, and thus unifies the model specifications of the two-wheel drive type and the four-wheel drive type.
In addition, since the slide gear 62 is also used in the high and low speed range of the auxiliary transmission 26, not only the configuration of the apparatus is simplified, but also the number of gears to be provided in the auxiliary transmission 26 is reduced and the cost of the apparatus is reduced. Is achieved.

Further, since the slide gear 62 and the ultra-low speed gear 65 are interlocked with the creep transmission device 70, when adding a creep range to the traveling system mission 6, only the creep transmission device 70 is mounted on the output side of the sub-transmission device 27. Therefore, it is not necessary to add a new gear to the main transmission shaft 23 or the auxiliary transmission shaft 24. Further, only the super-low speed gear 65 is unnecessary when the creep transmission device 70 is not attached, and this also reduces the number of gears to be provided in the traveling system mission 6.
Further, since the hydraulic pump 90 provided outside the mission case 5 is provided in a state where it is supported by the pump support portion 91 in the upper space of the mounting portion 19a, the hydraulic pump 90 is provided at the upper portion of the mission case 5. Thus, an accommodation space for the cabin air conditioner unit is secured above the transmission case 5, and the cabin 12 and the cabin 12 are placed close to the vehicle body 1a. It is possible to lower the floor.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments.
For example, a configuration in which the propulsion shaft 21 can be connected to the engine 4 via a clutch device may be employed. In this configuration, the clutch device includes a flywheel fixed to an end portion of the crankshaft of the engine, a clutch disc pressed against the end surface of the flywheel by a pressure plate, a diaphragm spring that applies a pressing force to the pressure plate, The propulsion shaft 21 is connected to a clutch disk.

Further, although the shuttle speed change means 25 has a hydraulic configuration, a synchronous configuration such as a key type inertia lock type may be adopted instead of the configuration.
In the shuttle transmission 25, it is also possible to adopt a configuration of a reverse gear train that transmits the power from the engine 4 to the counter shaft 22 at a constant speed. Of course, it is also possible to adopt a configuration of a reverse gear train that transmits power at the same speed as the rotary gear train.
Further, the main transmission 26 may employ a gear having a plurality of speeds other than the four speeds, such as a two-speed or a three-speed, and each of the main transmission 26 and the sub-transmission 27 may be employed. The configuration of acceleration / deceleration (gear ratio) by the combination of the gear diameters of the gear train can be appropriately changed according to the application of the model.

Further, without reducing the distance between the counter shaft 22 and the main transmission shaft 23, the distance between the shafts is made as conventional, and the gear diameter setting range of each gear stage of the main transmission 26 is expanded. Thus, the shift range of the main transmission 26 can be expanded.
Further, a configuration in which the medium speed gear 78 is meshed with the third speed output gear 52c can be employed.

1 is an overall cross-sectional view of a transmission embodying the present invention. It is the schematic which shows the whole structure of this transmission. It is sectional drawing which expands and shows a shuttle transmission and a main transmission. It is sectional drawing which expands and shows an auxiliary transmission. It is sectional drawing which expands and shows a creep transmission. It is sectional drawing which expands and shows the periphery of a front-wheel moving gear train. It is a rear view which shows the arrangement state of each gear and a shaft. It is a rear view of a mission case. It is sectional drawing which expands and shows the periphery of a hydraulic pump. It is a top view which expands and shows the periphery of a hydraulic pump. It is a left view of a tractor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tractor 4 Engine 5 Mission case 6 Traveling system mission 7 PTO system mission 8 Transmission 18 Front transmission case 19 Rear transmission case 19a mounting part 21 Propulsion shaft 22 Counter shaft 23 Main transmission shaft 24 Subtransmission shaft 25 Shuttle transmission device 26 Main transmission device 27 Sub-transmission device 29 PTO input shaft 34 Intermediate wall 35 Front cover 40 Clutch body 49f Forward rotation gear 49r Reverse rotation gear 50 Back idler gear 51a First speed input gear 51b Second speed input gear 51c Third speed input gear 51d Fourth speed Input gear 52a First speed output gear 52b Second speed output gear 52c Third speed output gear 52d Fourth speed output gear 60 Low speed gear 61 Transmission gear 62 Slide gear 65 Super low speed gear 70 Creep transmission 71 Casing 75 Creep first Gear 77 Creep second gear 80 Rear wheel differential device 84 Front wheel moving shaft 86 Front wheel moving gear 90 Hydraulic pump 91 Pump support portion 91a mounting surface 91b opening 92 Pump shaft 93 Pump power transmission mechanism 96 Pump transmission gear

Claims (7)

A counter shaft (22), a main transmission shaft (23), and an auxiliary transmission shaft (24) are provided in parallel to each other, and a main transmission (26) is provided between the counter shaft (22) and the main transmission shaft (23). The auxiliary transmission device (27) is provided between the main transmission shaft (23) and the auxiliary transmission shaft (24), respectively.
The auxiliary transmission (27) is provided on a main transmission shaft (23) and is a low-speed gear (60) that rotates integrally with the main transmission shaft (23), and one gear of the main transmission (26). A transmission gear (61) meshed and loosely fitted to the auxiliary transmission shaft (24) and freely slidable in the axial direction and integrally rotatable on the auxiliary transmission shaft (24). A slide gear (62) meshable with the gear (60),
By the sliding gear (62) is engaged with the transmission gear to release the engagement between the low-speed gear (60) (61), rotate integrally with the transmission gear (61) the sub transmission shaft (24) to be able to configure,
An ultra-low speed gear (65) rotating integrally with the main transmission shaft (23) is provided on the main transmission shaft (23), and creep shift is performed between the ultra-low speed gear (65) and the auxiliary transmission shaft (24). Device (70), the creep transmission (70) includes a first creep gear (75) meshing with the ultra-low speed gear (65), and a second creep gear interlocking with the first creep gear (75). and a gear (77), the transmission of the tractor sliding gear releasing the engagement between the low-speed gear (60) to the creep second gear (77) (62), characterized in interlockable der Rukoto.   2. The tractor shift according to claim 1, wherein the slide gear (62) increases the speed of the auxiliary transmission shaft (24) by interlocking with the one gear of the main transmission (26). apparatus. The creep transmission (70) includes a casing (71) that rotatably supports the first and second gears (75) and (77) of the creep, and the casing (71) is disposed outside the transmission case (5). tractor transmission according to claim 1 or claim 2, characterized that you have inserted removably from. The sub-transmission (27) meshes with a gear different from the one gear of the main transmission (26), and a different speed gear (78) loosely fitted to the sub-transmission shaft (24), and the slide gear (62) of claims 1 to 3, characterized that you have a clutch member for coupling said heterologous gear (78) when the neutral position to the sub speed change shaft (24) (79) A transmission for a tractor according to any one of the above. A counter shaft (22), a main transmission shaft (23), and an auxiliary transmission shaft (24) are provided in parallel to each other, and a main transmission (26) is provided between the counter shaft (22) and the main transmission shaft (23). The auxiliary transmission device (27) is provided between the main transmission shaft (23) and the auxiliary transmission shaft (24), respectively.
The auxiliary transmission (27) is provided on a main transmission shaft (23) and is a low-speed gear (60) that rotates integrally with the main transmission shaft (23), and one gear of the main transmission (26). A transmission gear (61) meshed and loosely fitted to the auxiliary transmission shaft (24) and freely slidable in the axial direction and integrally rotatable on the auxiliary transmission shaft (24). A slide gear (62) meshable with the gear (60),
The slide gear (62) disengages from the low-speed gear (60) and engages with the transmission gear (61), so that the transmission gear (61) rotates integrally with the auxiliary transmission shaft (24). Configure as possible
The sub-transmission (27) meshes with a gear different from the one gear of the main transmission (26), and a different speed gear (78) loosely fitted to the sub-transmission shaft (24), and the slide A transmission for a tractor, comprising: a clutch member (79) for connecting the different speed gear (78) to the auxiliary transmission shaft (24) when the gear (62) is in a neutral position . A propulsion shaft (21) interlocking with the engine (4) is provided in front of the extension line of the main transmission shaft (23), and the main transmission (26) is provided between the propulsion shaft (21) and the counter shaft (22). ) Is provided with a shuttle transmission (25) for supplying normal or reverse power, and the shuttle transmission (25) decelerates at least the normal power and transmits it to the counter shaft (22). The tractor transmission according to any one of claims 1 to 5, wherein: The main transmission (26) decelerates the power transmitted from the shuttle transmission (25) to be transmitted to the main transmission shaft (23), and the power transmitted from the shuttle transmission (25). transmission of the tractor according to claim 6, characterized in Rukoto which have a a gear train for transmitting the accelerated to the main transmission shaft (23) a.

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