JP2569340Y2 - Transmission structure of agricultural tractor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a structure of a transmission including a main speed change mechanism, a forward / reverse switching mechanism, and the like of an agricultural tractor.

[Problems to be Solved by Conventional Technology and Invention] Generally, a transmission of this kind of agricultural tractor transmits power input from an engine to a traveling power transmission system and a PT.
In addition to being distributed to the O power transmission system, the traveling power transmission system is configured to transmit power to the traveling wheels via a transmission mechanism such as a main transmission mechanism and a front-rear switching mechanism.

By the way, in today's agricultural tractors, it is known that a flat step (driver's seat floor surface) is formed in front of a transmission case, but the conventional transmission is a main and auxiliary of the traveling power transmission system. Since the transmission mechanism is arranged in series in the front-rear direction or parallel in the left-right direction in the transmission case, it is a large one, and sufficient space for steps cannot be secured. And getting on and off is a problem.

[Means for Solving the Problems] The present invention has been made in order to provide a transmission structure of an agricultural tractor capable of eliminating these disadvantages in view of the above-described circumstances. The engine power input to the input shaft supported by the front and rear shaft supports is distributed to the PTO power transmission system and the traveling power transmission system, and the traveling power transmission system includes a main / sub transmission mechanism and a forward / reverse switching mechanism. In the transmission of the agricultural tractor interposed, the PTO drive shaft for transmitting power to the PTO power transmission system is connected in series to the rear end of the input shaft from the rear shaft support via a one-way clutch, A main transmission counter shaft, a main transmission shaft, and a reverse gear shaft for transmitting power to a traveling power transmission system are provided in parallel with the input shaft,
A pair of front and rear idler gears for transmitting power to the main transmission counter shaft and the reverse gear shaft are respectively fitted between the front and rear shaft supports of the input shaft so as to be close to the front and rear shaft supports, respectively. Between the transmission gears, a sliding sleeve that selectively meshes with the forward and backward idler gears and switches between forward and backward is provided so as to be rotatable integrally, and constitutes a forward / backward switching mechanism. The first input gear integrally formed is meshed with the front idler gear, and the second input gear is provided to be freely rotatable on the reverse gear shaft, and meshed with the reverse gear meshed with the rear idler gear. The forward / reverse output from the input shaft via the forward / reverse switching mechanism is transmitted to the main shift counter shaft by a gear mesh formed between the front and rear shaft supports of the input shaft, and the output from the main shift counter shaft is further transmitted. Are located between the first and second input gears. The transmission is transmitted to the main transmission shaft via a main transmission mechanism that is provided with a transmission gear that is provided so as to be axially movable and integrally rotatable about the axis so as to selectively mesh with the force gear. The transmission is transmitted to a differential mechanism constituting a traveling power transmission system via an auxiliary transmission mechanism provided coaxially behind the transmission shaft and the main transmission counter shaft and arranged at a position parallel to the one-way clutch. It is characterized by the following.

According to the present invention, the transmission is downsized to improve the livability and getting on and off the vehicle.

Next, an embodiment of the present invention will be described with reference to the drawings.
In the drawings, 1 is a traveling body of an agricultural tractor,
The traveling body 1 transmits the power of the engine 3 installed below the bonnet 2 to the PTO shaft 5 and the front and rear wheels 6 and 7 via a power transmission mechanism installed in a transmission case 4 described later. A flat step 10 serving as a floor of a driver's seat 9 is provided on the upper surface of the clutch case 8 interposed between the engine 3 and the transmission case 4, that is, on the front part of the transmission case 4. Are formed.

Reference numeral 11 denotes an input shaft of the transmission case 4. The input shaft 11 is rotatable in the transmission case 4 by bearings 12 and 13 disposed at predetermined intervals in front and rear. The engine power is input through a clutch mechanism housed in the clutch case 8 while being supported by the input shaft 11.
It is connected via a one-way clutch 15 to a PTO drive shaft 14 arranged in series behind 11. That is, input shaft 11
The input power is one-way clutch 15, PTO drive shaft 1
4, and further transmitted to the PTO shaft 5 via the PTO transmission mechanism 16.

On the other hand, reference numerals 17 and 18 denote idler gears which are located between the two bearings 12 and 13 of the input shaft 11 and which are rotatably fitted to the outside.
Reference numeral 17 denotes a main transmission counter shaft 19 arranged in parallel below the input shaft 11.
Meshes with the first input gear 19a of the
Is engaged with the input gear 21a of the reverse gear 21 (the output gear 21b meshes with the second input gear 19b of the main transmission counter shaft 19), which is rotatably fitted on the reverse gear shaft 20. , 18
Are provided near the bearings 12 and 13, respectively.

Reference numeral 22 denotes a sliding sleeve externally fitted to the input shaft 11 between the front and rear idler gears 17, 18.
Is fitted to the input shaft 11 by spline fitting.
The sliding sleeve 22 is integrally rotatable and slidable back and forth. First and second gears 22a and 22b are formed at a front end and a rear end of the sliding sleeve 22, respectively. Is formed with a fork groove 22c into which a shifter fork (not shown) of the forward / reverse switching operation mechanism is fitted. That is, when the sliding sleeve 22 is located on the front side by the sliding caused by the operation of the forward / reverse switching operation mechanism, the first gear 22a meshes with the internal gear 17a formed on the front idler gear 17. In the rear position, the second gear 22b meshes with the internal gear 18a formed on the rear idler gear 18.
When the sliding sleeve 22 meshes with the front idler gear 17, the engine power is directly transmitted to the main transmission counter shaft 19, while when the sliding sleeve 22 meshes with the rear idler gear 18, the engine moves in reverse. The engine power is transmitted to the main transmission counter shaft 19 via the gear 21, and a forward / reverse switching mechanism 25 is provided.
Is composed.

Further, reference numeral 23 denotes a main transmission shaft arranged in parallel below the main transmission counter shaft 19, and the main transmission shaft 23 is provided with various transmission gears constituting a main transmission mechanism 24. That is, the main transmission mechanism 24 is arranged below the forward / reverse switching mechanism 25, and the transmission gear 24a constituting the main transmission mechanism 24 is axially movable with respect to the main transmission shaft 23. The speed change gear 24a is located between the first and second input gears 19a and 19b, and is selectively meshed with the input gears 19a and 19b. It has become. The traveling power passing through the main transmission mechanism 24 is transmitted to the front and rear wheels 6, 7 behind a main transmission mechanism 24 via a sub transmission mechanism 26 disposed coaxially with the counter shaft 19 and the main transmission shaft 23. Are transmitted to the differential mechanisms 27 and 28. Reference numeral 29 denotes a forward / reverse switching lever.

In the embodiment of the present invention configured as described above, the forward / reverse switching mechanism 25 is disposed above the main transmission mechanism 24. That is, the front-rear length of the transmission case 4 can be reduced as compared with the case where the forward / reverse switching mechanism 25 is arranged in series with the main transmission mechanism 24, and accordingly, the transmission case 4 is formed in front of the transmission case 4. The length of the front and rear steps 10 can be sufficiently secured. As a result, the area of the step 10 can be increased, and the livability and getting on / off of the agricultural tractor can be improved.

Moreover, since the idler gears 17 and 18 of the input shaft 11 are provided close to the bearings 12 and 13, the shaft deflection of the input shaft 11 at the time of forward movement and at the time of reverse movement becomes equal, and the noise level at the time of overload is reduced. The difference can be eliminated.

The main transmission mechanism 24 includes a transmission gear that constitutes the mechanism 24.
24a is located between the first and second input gears 19a and 19b to which the forward and reverse outputs are transmitted and is selectively meshed with these, so that the main transmission mechanism 24 itself can be made compact. This contributes to downsizing of the transmission.

On the other hand, the power transmission to the PTO power transmission system is made directly to the PTO drive shaft 14 via the one-way clutch 15 at the rear of the input shaft 11, so that the PTO drive shaft 14 switches the traveling power transmission system back and forth. The rotation is output as a rotation in a fixed direction irrespective of the power transmission for switching the main transmission, while the overload from the PTO shaft 5 is automatically cut off by the one-way clutch 15 so that the PTO shaft 5 , While rotating in a fixed direction regardless of the switching state of the traveling power transmission system,
In this case, the work load does not affect the traveling power transmission system, so that there is an advantage that there is no problem even if the input shaft of the traveling system and the PTO shaft system is shared.

[Effects] In summary, since the present invention is configured as described above, when distributing the engine power input to the input shaft to the traveling power transmission system, the transmission mechanism provided in the power transmission system The forward / reverse switching mechanism provided between the input shaft, the reverse gear shaft, and the main transmission counter shaft, and the main transmission mechanism provided between the main transmission counter shaft and the main transmission shaft are located at substantially the same position in the front / rear direction. A sub-transmission mechanism is provided coaxially behind the main transmission counter shaft and the main transmission shaft so as to be in parallel with the one-way clutch.

In addition, the transmission is equipped with a PTO power transmission system and a transmission system with a traveling power transmission system with forward / reverse switching and main / sub transmission, but with four shafts arranged in parallel for convenience. As a result, the transmission can be made slim, and the contribution to downsizing can be made.

As a result, the space for disposing each of these transmission mechanisms and the one-way clutch is centralized, so that the front-rear length of the transmission can be shortened and the transmission can be made slim, and the step space formed in front of the transmission can be sufficiently provided. And the step area can be increased to improve the livability and getting on and off of the agricultural tractor.

In addition, since the pair of idler gears are located between the front and rear shaft support portions of the input shaft and are provided in close proximity to each other, the deflection of the input shaft at the time of forward movement and the reverse movement is equalized, so that the noise level difference at the time of overload is reduced. Forward and reverse output to the main transmission counter shaft via these idler gears is transmitted via gear meshes formed between the front and rear shaft supports of the input shaft, and furthermore, a pair of idler The power transmission to the main transmission shaft via the gears and the first and second input gears meshing with the respective gears is performed via the transmission gear located between the input gears and selectively meshing with the input gears. Because of the configuration, the front and rear length of the transmission case can be shortened, so that the transmission can be further slimmer and more compact.

[Brief description of the drawings]

The drawings show an embodiment of the transmission structure of the agricultural tractor according to the present invention. FIG. 1 is a side view of the agricultural tractor, and FIG. 2 is a schematic development showing a power transmission state of the transmission. FIG. 3 is a longitudinal sectional view of the transmission, and FIG. 4 is an enlarged view of a main part. In the figure, 1 is a traveling body, 3 is an engine, 4 is a transmission case, 5 is a PTO shaft, 6 is a front wheel, 7 is a rear wheel, 10 is a step, 11 is an input shaft, 12, 13 are bearings, and 14 is a bearing. PTO drive shafts, 17 and 18 are idler gears, 19 is a main transmission counter shaft, 19
a and 19b are input gears, 20 is a reverse gear shaft, 21 is a reverse gear, 22
Is a sliding sleeve, 23 is a main transmission shaft, 24 is a main transmission mechanism, 24a
Is a transmission gear, and 25 is an auxiliary transmission mechanism.

Claims (1)

(57) [Scope of request for utility model registration] An input shaft (11) supported by a front and rear support.
The engine power input to the power transmission system is distributed to the PTO power transmission system and the traveling power transmission system.
In a transmission of an agricultural tractor having a sub-transmission mechanism and a forward / reverse switching mechanism, a PTO drive shaft (14) for transmitting power to a PTO power transmission system is provided at a rear end from a rear shaft support of an input shaft. The main transmission counter shaft (19), the main transmission shaft (23), and the reverse gear shaft (20) for transmitting power to the traveling power transmission system are connected in series to each other via a one-way clutch (15). Provided in parallel with the shaft (11),
Main transmission counter shaft (19) between the front and rear shaft supports of the input shaft
And a pair of front and rear idler gears (17, 18) for transmitting power to the motor and the reverse gear shaft (20), respectively, are fitted close to the front and rear shaft supports, respectively. A sliding sleeve (22), which selectively meshes with the idler gear and switches between forward and reverse, is provided so as to be rotatable integrally, and constitutes a forward / backward switching mechanism (25). The first input gear (19a) formed on the front idler gear (1
7), the second input gear (19b) is freely rotatably provided on the reverse gear shaft, and meshes with the reverse gear (21) which meshes with the rear idle gear (18) to switch the forward / backward movement. The forward / reverse output from the input shaft (11) via the mechanism (25) is transmitted to the main transmission counter shaft (19) by gear engagement formed between the front and rear shaft supports of the input shaft, and further transmitted to the main transmission counter shaft (19). The main transmission shaft (23) is arranged so that the output from the transmission counter shaft is located between the first and second input gears (19a, 19b) and selectively meshes with the first and second input gears (19a, 19b). And transmitted to a main transmission shaft (23) via a main transmission mechanism (24) including a transmission gear (24a) provided so as to be axially movable and integrally rotated in a direction around the axis,
A differential mechanism that constitutes a traveling power transmission system via a subtransmission mechanism (26) provided coaxially behind the main transmission shaft and the main transmission counter shaft and disposed at a position parallel to the one-way clutch. 27) The transmission structure of an agricultural tractor, characterized in that the transmission is performed as described in (27).