JPH0761778B2 - Transmission structure of agricultural work vehicle - Google Patents

Description

TECHNICAL FIELD The present invention relates to a power transmission structure of an agricultural work vehicle such as an agricultural tractor, and more specifically, it is configured so that only front wheels can be steered, and the front wheels are substantially the same as the rear wheels. A front wheel transmission that can switch between a standard drive state in which the front wheels are driven at a higher speed and a front wheel speed increase state in which the front wheels are driven at a higher speed than the rear wheels is provided. The present invention relates to a transmission structure of an agricultural work vehicle configured to switch to a front wheel speed increasing state.

[Conventional technology]

In this type of transmission structure, conventionally, for example, JP-A-63-14
As disclosed in Japanese Patent No. 1828, it is configured to switch to the front wheel speed-increasing state in conjunction with only the steering operation of the steering wheel.

[Problems to be Solved by the Invention]

In the conventional structure, when the front wheel is steered greatly during turning of the machine, the front wheel is driven at high speed to increase the propulsive force and smoothly turn so as not to damage the field by pushing the rear wheel. This is because it is possible to drive.
However, as described above, since the switching to the front wheel acceleration state is a structure that is performed only by the steering operation of the steering wheel, for example, when traveling straight through a wetland or when pulling a root of a tree In some cases, it is not possible to drive the front wheels faster than the rear wheels to increase the propulsion force.

The present invention has been made in view of this point, and an object of the present invention is to provide a transmission structure for an agricultural work vehicle capable of arbitrarily setting a front wheel speed increasing state according to a work situation.

[Means for Solving the Problems]

A feature of the present invention is that, in the transmission structure of the agricultural work vehicle having the above-described configuration, a switching operation for manually setting the front wheel transmission to be set to the front wheel speed increasing state over a switching operation associated with the steering of the front wheels. Means, and further, the switching means,
This is because it is composed of an operation pedal that releases the linkage between the front wheel transmission and the steering mechanism by depressing the first step and switches the front wheel transmission to the front wheel accelerating state by depressing the second step. The effects are as follows.

[Action]

In other words, by artificially operating the operating pedal,
The front wheel transmission in the standard drive state is forcibly set to the front wheel speed-increasing state in preference to the front wheel steering, that is, regardless of the front wheel steering.

〔The invention's effect〕

As a result, the front wheels can be accelerated while the front wheels are set in the straight-ahead posture during towing work or traveling in wetlands. Therefore, not only when the vehicle body turns, but also when the vehicle goes straight ahead, the propulsive force of the vehicle body can be increased, and the running performance can be improved.

Further, the switching means is composed of an operating pedal that releases the linkage between the front wheel transmission and the steering mechanism by depressing the first step and switches the front wheel transmission to the front wheel accelerating state by depressing the second step. Therefore, for example, in the case where the switching means is composed of an operation lever for operating the front-rear direction to release the linkage between the front wheel transmission and the steering mechanism and for operating the left-right direction to switch the front wheel transmission to the front-wheel speed-up state. On the other hand, if you want to bring the front wheel acceleration state immediately before turning, you can start the turning operation with both hand handles and bring the front wheel acceleration state with the operation pedal, and you can bring it with one hand like when operating with the lever. There is no need to perform an unstable operation such as turning the operating lever to the front wheel speed-up state after starting the turning operation with the handle, and the front wheel speed-up operation just before turning can be performed. There.

EXAMPLES Examples of the present invention will be described below with reference to the drawings.

FIG. 6 shows an agricultural tractor as an agricultural vehicle according to the present invention. This agricultural tractor has an engine (1) mounted at the front of the machine body, a mission case (2) at the rear, a driving section (3) at the center of the machine, and a pair of front and rear drive wheels (4), (5). ) Is deployed and configured.

Steering handle (6) provided in the driving section (3)
The front wheels (4) and (4) are configured to be steerable in accordance with the turning operation of the front wheels (4) and (4) and the front wheels (4) and (4) are driven at substantially the same speed as the rear wheels (5) and (5). A front wheel transmission (9) capable of switching between a standard drive state and a front wheel speed increasing state in which the front wheels (4) and (4) are driven at a higher speed than the rear wheels (5) and (5).
Is provided. This front wheel transmission (9) is arranged in a front wheel high speed case (11) connected to the rear part of the engine (1) via a main clutch case (10).

A steering gear box (13) rotatably supporting a handle operating shaft (12) is fixed to the upper surface of the front wheel shift case (11). Next, the transmission system from the main clutch to the front wheel transmission (9) will be described. As shown in FIG.
The output shaft (15) provided with the main clutch mechanism (14) is projected from the main clutch case (10) to be supported in the front wheel transmission case (11), and in the front wheel transmission case (11),
A first transmission shaft (1) located below the output shaft (15) and transmitting power to the input shaft (16) on the mission case (5) side.
7), and further below the second transmission shaft (18) which receives the front wheel driving force from the mission case (5), and the axial center of which is aligned with the inner end of the second transmission shaft (18). The third transmission shaft (1
9), the fourth transmission shaft (21) to the front axle case is provided below the third transmission shaft (19). Output shaft (1
The first gear (22) is attached to 5) and the second gear (23) is attached to the first transmission shaft (17) to transmit the transmission to the first transmission shaft (17) through this gear transmission mechanism, and at the same time, to transmit the first transmission. The power transmitted from the shaft (17) to the mission case (5) is transmitted to the second transmission shaft (18) as front wheel driving force. On the other hand, a pair of large and small third gear (24) and fourth gear (25) are attached to the first transmission shaft (17).
A relay transmission member (26) integrally formed with and is loosely fitted, and a friction multi-plate clutch mechanism (27) is attached to the third transmission shaft (19).
And the inner end of the second transmission shaft (18) is connected to the fifth gear (2
8) is integrally formed. Here, the clutch mechanism (2
7) is the 6th gear (2) which always meshes with the 3rd gear (24)
9), a clutch case (30), a rotating member (31) which cooperates with the clutch case (30) to support the friction multi-plate, one end of which acts on the friction multi-plate, and the other of which is provided on the other end. The internal gear (18A) of the two transmission shafts (18) and the clutch sleeve (33) provided with the external gear that can be freely engaged and disengaged. Further, at the front end of the third transmission shaft (19) and the rear end of the fourth transmission shaft (21), the seventh gear (34) and the eighth gear (3
And 5) are spline-fitted to form a transmission structure for the fourth transmission shaft (21).

Therefore, the clutch sleeve (33) is connected to the second transmission shaft (1
When engaged with the internal gear (18A) of 8), the second transmission shaft (1
The power transmitted to 8) is transmitted to the third transmission shaft (19) through the clutch sleeve (33), and the front drive state (4) and the rear drive wheel (5) are driven at approximately the same speed. When the clutch sleeve (33) is operated in the opposite direction while operating the clutch mechanism (27), the power transmitted to the second transmission shaft (18) is transmitted to the relay transmission member (26) and the clutch case (30). ) Is transmitted to the third transmission shaft (19), and the front wheel (4) is driven at a high speed with respect to the rear wheel (5) so that a high-speed driving state appears.

The operation mechanism for the front wheel transmission (9) as described above will be described in detail. As shown in FIG. 1 and FIG. 4, this operating mechanism is composed of a device described later, but it is integrated into a cassette type and can be attached to and detached from the lateral side surface of the front wheel transmission case (11). Is. First, a pitman arm (3) that constitutes a steering mechanism pivotally supported by a sideways operation shaft (37) with respect to a mounting case (36) of the operation mechanism and that is pivotally supported by the steering gear box (13).
8) and a link plate (4) as a mechanical linking mechanism between the operation shaft (37) and an intermediate portion of the operation arm (39).
0) and the clutch mechanism (27) is operated by steering operation. A support holder (41) is supported at the inner end of the operation shaft (37) in a state where the operation shaft (37) is allowed to rotate, and the support holder (41) and the inner wall surface of the mounting case (36). A sliding rod (42) is installed between the sliding shaft and the sliding rod (42) so that the sliding rod (42) can slide in the axial center (Y) direction orthogonal to the axial center (X) of the operating shaft (37). Configured.

A rotary roller (44) is attached to one end of the sliding rod (42) through a support member (43) and is rotatable integrally with the operating shaft (37) and in the axial (X) direction. A slidable cam plate (45) is fitted over the spline. As shown in FIG. 5, this cam plate (45)
The sliding rod (42) acts on the roller (44) by the rotation of the cam plate (45) around the axis (X).
Of small diameter cylindrical part (45
A cam surface composed of b) and a large diameter cylindrical portion (45a) is formed. The support member (4) in the sliding rod (42)
A shift fork (46) acting on the clutch sleeve (33) of the front wheel transmission (9) is provided at an end portion on the side opposite to 3).
The shift fork (46) includes a first spring (47) interposed between the support holder (41) and the base end of the shift fork (46), and a sliding rod (42). The second spring (48) interposed between the shift fork (46) and the base end of the shift fork (46) neutrally urges the cam plate (45) and the rotary roller (44) to contact each other.
Movement is restricted. When the steering operation amount is equal to or less than a predetermined amount (rotation angle is 40 ° or less), the small-diameter cylindrical portion (45b) of the cam plate (45) is located at a position corresponding to the rotation roller (44). The shift fork (46) is located on the right side in FIG. 4 with the rotating roller (44) and the small diameter cylindrical portion (45b) separated from each other, and the clutch sleeve (33) is engaged with the internal gear (18A). The standard drive state of the front wheels is revealed. From this standard drive state, when the pitman arm (38) is rocked by steering operation, one of the two large-diameter cylindrical parts (45a) is rotated by the rotating roller (4).
4), the sliding rod (42) is moved leftward in FIG. 4, and the clutch mechanism (27) is actuated so that the high-speed driving state appears. The cam plate (45) is equipped with a shift operation member (49), and the cam plate (45) is moved in the axial center (X) direction of the operation shaft (37) to correspond to the rotating roller (44). The cam plate (45) slides into the sliding rod (42) even if the steering wheel is operated.
The shift operating member (49) constitutes a mechanism for restricting the high-speed drive state without moving the.

Then, the switching means (A) for performing the switching setting to the front wheel speed increasing state by the manual operation, prior to the switching operation of the front wheel transmission (9) accompanying the steering operation of the front wheels (4) and (4) as described above. Is provided. That is, as shown in FIG. 1 and FIG. 2, the linking member (50) extending in the front-rear direction is pivotally connected to the swing end of the operating arm (39), and the linking member (50) of the linking member (50) is connected. A long hole (54) that is long in the front-rear direction is formed in the rear portion so that a pin (53) at the tip of a drive arm (52) interlocked with an operation pedal (51) is engaged. In addition, a long hole (55) that allows the operation arm (39) to swing regardless of the movement of the pitman arm (38) is formed in the connecting portion of the operation arm (39) with the link plate (40). And the link plate (40) is urged downward during steering operation, and the long hole (55)
Pin (40) of the link plate (40) in the central recess (55a)
a) is engaged, and the operation arm (39) is configured to interlock with the steering of the front wheels. Then, in the vicinity of the connecting portion, the pin (40
A cam plate (56) for releasing the engagement with the recess (55a) of a) is provided, and after setting the operation arm (39) in a state independent of the movement of the pitman arm (38), the operation pedal (5) is further added.
When step 1) is depressed, the operating arm (39) swings and the front wheel speed-up state can be forcibly set. The operation pedal (51), the link member (50), the cam plate (56), and the long hole (55).
This constitutes the switching means (A).

[Another embodiment]

The front wheel speed increasing ratio in the front wheel speed increasing state by the switching means (A) may be different from the front wheel speed increasing ratio in the front wheel speed increasing state accompanying front wheel steering.

It should be noted that reference numerals are added to the claims for convenience of comparison with the drawings, but the present invention is not limited to the structures of the accompanying drawings by the entry.

[Brief description of drawings]

The drawings show an embodiment of a transmission structure for an agricultural work vehicle according to the present invention. Fig. 1 is a side view of a main part, Fig. 2 (a) is a side view of the main part at the time of front wheel speed-up operation accompanying front wheel steering, FIG. 2 (B) is a side view of a main part of the front wheel accelerating operation by human operation, FIG. 3 is a vertical side view of the front wheel transmission, FIG. 4 is a cross-sectional plan view of the speed change operation system, and FIG. 5 is a cam. FIG. 6 is a side view of the plate, and FIG. 6 is an overall side view of the agricultural tractor. (4), (4) ... front wheel, (5), (5) ... rear wheel,
(9) ... front wheel transmission, (38) ... steering mechanism, (51) ... operation pedal, (A) ... switching means.

Claims (1)

[Claims] 1. A standard driving state in which only the front wheels (4), (4) are steerable and the front wheels (4), (4) are driven at substantially the same speed as the rear wheels (5), (5). And a front wheel transmission (9) capable of switching the front wheels (4), (4) to a front wheel speed increasing state in which the front wheels (4), (4) are driven faster than the rear wheels (5), (5), and the front wheels (4), ( A transmission structure of an agricultural work vehicle configured to switch from a standard drive state to a front wheel speed-increasing state in accordance with a steering amount more than a set amount of 4), which is used for steering the front wheels (4), (4). Prior to the accompanying switching operation, there is provided switching means (A) for switching and setting the front wheel transmission (9) to the front wheel speed increasing state by manual operation, and further, the switching means (A).
The operation of switching the front wheel transmission (9) to the front wheel speed-increasing state by releasing the linkage between the front wheel transmission (9) and the steering mechanism (38) by depressing the first step Transmission structure for agricultural work vehicles, which consists of pedals (51).