JPH0362569B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a transmission system for steerable front wheels with a standard drive state in which power is transmitted at a drive speed approximately equal to the rear wheel drive speed, and a rear wheel drive speed The present invention relates to a front wheel speed change operation structure for an agricultural tractor equipped with a clutch type front wheel speed change device that switches to an increased speed drive state in which transmission is performed at a higher drive speed.

[Conventional technology]

A clutch-type structure for switching the front wheels of an agricultural tractor between the standard drive state and the accelerated drive state as described above is disclosed, for example, in Japanese Utility Model Application Publication No. 102133/1980, but this is a permanent-bit type structure. gear mechanism and 2
This mechanism consists of two hydraulic friction clutches, and by disengaging and disengaging the friction clutches, the system changes the path of the engine power transmitted through the permanent gear mechanism and performs gear shifting. had the following problem.

[Problem that the invention seeks to solve]

In agricultural tractors, the front wheels are shifted to an increased speed drive state when changing direction with a small turning radius at the edge of a ridge, or when making a sharp turn to avoid an immediate danger. In general, there are many cases where the gear shifting operation must be performed quickly, so
A transmission mechanism using a hydraulic friction clutch is suitable for this purpose because it can perform a gear shifting operation in one action, but friction clutches are generally expensive and tend to complicate the overall structure of the transmission. On the other hand, the front wheels are shifted to the standard drive state during normal work or when driving on the road, but in such cases there are generally few opportunities to shift gears quickly, and the need for a friction clutch is reduced to increase speed. Although this is lower than in the drive state, the conventional structure described above uses a hydraulic friction clutch for shifting operations in both the standard and increased drive states, which increases manufacturing costs and complicates the device. It was inviting a transformation.

An object of the present invention is to reduce the cost and simplify the structure of the front wheel transmission without deteriorating its functionality.

[Means for solving problems]

A feature of the present invention is that, in the above-mentioned front wheel transmission structure for an agricultural tractor, the clutch of the standard drive system of the front wheel transmission is configured as an articulating clutch, and the clutch of the speed increasing drive system is configured as a hydraulic friction clutch. , and the shift member of the interlocking clutch is mechanically operated in conjunction with the movement of the piston member in the friction clutch, so that both clutches are engaged and operated in a reverse manner, and the shift member is elastically operated. A spring is interposed between the piston member and the shift member so that the clutch can be engaged.The functions and effects of the spring are as follows.

[Effect]

As mentioned above, by replacing one of the conventional two hydraulic friction clutches with a mechanical articulating clutch, which is lower in cost than the hydraulic type, a part of the hydraulic system path is omitted and the structure is simplified. As well as becoming
Cost reduction can be achieved. In addition, by linking the piston member of the friction clutch with the shift member that controls the on/off operation of the articulating clutch, the on/off operation of both clutches can be performed only by operating the piston of the friction clutch. The structure has been simplified.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to reduce the cost and simplify the structure of the front wheel transmission in an agricultural tractor. In addition, since the gear shifting operation in both the standard and increased speed states is configured to be turned on and off in a contradictory manner by the piston member of the friction clutch, which is a common member for both operations of the articulating clutch and the friction clutch, the above-mentioned Both clutches are never engaged at the same time, and the structure prevents damage caused by this. Furthermore, since the piston member and the shift member of the occlusal clutch are elastically interlocked by a spring, when the occlusal clutch is operated to the engaging side, even if the phases of the occlusal parts of the occlusal clutch are not aligned, the clutch is The engaging operation is absorbed by the spring, and when the phases of the occlusal parts are aligned, the biasing force of the spring causes the occlusal force to engage, resulting in the engaged state, so that the engaging operation of the occlusal type clutch can be performed without difficulty. Summer.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An agricultural tractor that is an embodiment of the present invention will be described below based on the drawings.

As shown in FIG. 4, a fuselage frame 3 that supports a pair of left and right steering-type front wheels 1, 1 and rear wheels 2, 2 in a freely drivable manner includes an engine 4, a main clutch 5, a transmission case 6, and a control section. 7, a lift arm 8 that can be driven up and down to freely swing up and down to connect various work devices such as a rotary tiller to the rear of the machine, and a PTO that transmits power to the work devices.
A four-wheel drive agricultural tractor is constructed by providing a shaft 9.

Next, the power transmission system and front wheel transmission 10 of the agricultural tractor will be described in detail. As shown in FIGS. 3 and 4, power from the engine 4 is transmitted to the transmission case via the main clutch 5 and the power transmission shaft 11. The main transmission (not shown) in 6 and the sub-transmission 1
2 to drive the rear wheels 2, 2, and gears 12a, 12b of the sub-transmission device 12.
The power branched from is sent to the front wheel transmission transmission unit 14 in the front wheel transmission device 10 for gear shifting operation, and is sent to the front wheel differential mechanism 1a via the front wheel output shaft 15 to drive the front wheels 1, 1. are doing.

To explain the front wheel transmission transmission part 14 in detail, as shown in Figs. 12b is fixed to the output wheel body 17a which is loosely fitted to the front wheel output shaft 15, and this output wheel body 17a
A hydraulic friction clutch 17 is provided between the front wheel output shaft 15 and the front wheel output shaft 15. Further, the rear end of the piston 17b of the friction clutch 17 is moved in the axial direction of the front wheel output shaft 15 by the engagement action of the piston 17b and the biasing force of the spring 20, and is integrated with the front wheel output shaft 15 by a spline structure. A rotatable shift member 18 is fitted onto the outside, and the claw portion 18a of the shift member 18 is engaged with the engaging portion 13a of the first driven gear 13 to shift the first driven gear 13 and the first driven gear 13. Member 18
An interlocking clutch 19 is formed between the two.

In FIG. 1, pressure oil is supplied from a pump (not shown) to the friction clutch 17 through the oil passage 15a, and the piston 1
7b is moved to put the friction clutch 17 in the engaged state, and the shift member 18 that engages and interlocks with the piston 17b is separated from the engaging portion 13a of the first passive gear 13, and the articulating clutch 19 is in the disengaged state. It shows. This state is a state in which the front wheels 1, 1 are being shifted to an increased speed driving state.

Next, as shown in FIG. 2, when the supply of pressure oil to the friction clutch 17 is stopped, the piston 17b retreats due to the biasing force of the spring 17c, and the friction clutch 17 is in the disengaged state, while the biasing force of the spring 20 As a result, the shift member 18 moves toward the first driven gear 13, and the claw portion 18a of the shift member 18 engages with the engaging portion 13a of the first driven gear 13, and the engagement type clutch 19 enters the engaged state. In this state, the front wheels 1, 1 are being shifted to the standard drive state.

In the manner described above, the front wheels 1, 1 are shifted to both the standard and increased speed states.

[Another example]

In the above embodiment, as shown in FIGS. 1 and 2, the spring 20 that biases the shift member 18 toward the engagement type clutch 19 is supported by the output wheel 17a of the friction clutch 17. A structure may be adopted in which the piston 17b is provided with a support portion to support the spring 20.

[Brief explanation of drawings]

The drawings show an embodiment of the front wheel speed change operation structure for an agricultural tractor according to the present invention, in which FIG. 1 is a vertical cross-sectional side view showing a state in which the front wheel transmission is being changed to a speed increasing drive state, and FIG. 2 is a front wheel speed change operation structure. FIG. 3 is a plan view of the vicinity of the auxiliary transmission and front wheel transmission, and FIG. 4 is an overall side view of the agricultural tractor. 1...Front wheel, 10...Front wheel transmission, 17...
Friction clutch, 17b...Piston member, 18...
...Shift member, 19...Articulating clutch, 20...
…Spring.

Claims (1)

[Claims] 1 A clutch is provided in the transmission system for the freely steerable front wheels 1, 1 to switch between a standard drive state in which power is transmitted at a drive speed approximately equal to the rear wheel drive speed, and an increased speed drive state in which power is transmitted at a drive speed greater than the rear wheel drive speed. This is a front wheel transmission operation structure for an agricultural tractor equipped with a front wheel transmission 10 of the type, in which the clutch 19 of the standard drive system of the front wheel transmission 10 is configured as an articulating clutch 19, and the clutch 17 of the speed increasing drive system is configured as an articulating clutch 19. A hydraulic friction clutch 17 is constructed, and the shift member 18 of the articulating clutch 19 is mechanically operated in conjunction with the movement of the piston member 17b in the friction clutch 17, so that both clutches 17 and 19 are moved in opposite directions. The piston member 17b and the shift member 1 are configured to engage and disengage automatically, and to elastically engage the shift member 18.
A front wheel gear shift operation structure for an agricultural tractor in which a spring 20 is interposed between the front wheel and the front wheel.