JPH0362570B2 - - 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 gear shift operation structure for an agricultural tractor equipped with a clutch type front wheel gear shifter that switches to an increased drive state in which transmission is performed at a higher drive speed.

[Conventional technology]

In agricultural tractors equipped with a front wheel transmission as described above, the first drive system of the front wheel transmission is
The clutch and the second clutch of the speed-increasing drive system are configured to be selectively engaged and operated by forward and reverse operation of the shift member, and the clutch and the second clutch of the speed increasing drive system are configured to be selectively engaged and operated by forward/reverse operation of the shift member. Some vehicles are configured so that the front wheel transmission is automatically operated to the speed increasing drive side when turning.

In this way, by increasing the speed of the front wheels when turning, it is possible to make sharp turns without disturbing the ground. The configuration is also such that the connection between the human operating tool and the shift member is cut off, so that the front wheels can be kept in the standard drive state both when traveling straight and when turning.

[Problem that the invention seeks to solve]

Generally, once a transmission is operated to a certain shift position, it remains at that shift position unless operated again. Therefore, when turning using the front wheel speed increasing effect as described above, if the return operation of the manual operation tool after the turn is insufficient, the front wheel transmission will be operated to the speed increasing drive side. There is a risk that it will be left behind.

As a result, if the connection between the manual operating tool and the shift member of the front wheel transmission is cut off in the above state, the front wheel transmission will not be able to return from the speed-up drive side to the standard drive side, and the front wheels will be locked when driving straight. A problem may occur in which the motor is driven at an increased speed.

An object of the present invention is to configure the front wheel transmission to reliably return to the standard drive side when the front wheel transmission is not operated to the speed increasing drive side.

[Means for solving problems]

The present invention resides in the front wheel speed change operation structure for an agricultural tractor as described above. In other words, the first clutch of the standard drive system and the second clutch of the speed-up drive system of the front wheel transmission are configured to be selectively engaged and operated by forward/reverse operation of the shift member, and are configured to be operated as manual operating tools. A switching mechanism is provided for switching the shift member of the front wheel transmission between a linked state and a non-linked state, and the switching mechanism biases the linkage system of the front wheel transmission toward the standard drive side. The effects are as follows.

[Effect]

With the configuration described above, even if the manual operating tool is not fully returned after a turn is completed after operating the front wheel transmission to the speed-increasing drive side, the front wheel transmission changes to the standard state due to the biasing force. It is operated securely by returning it to the drive side.

Furthermore, if the switching mechanism is switched to the non-coupled state, the front wheel transmission is always reliably held on the standard drive side by the biasing force.

〔Effect of the invention〕

As described above, even if the return operation of the manual operation tool at the end of a turn is not sufficient, or even if the link between the manual operation tool and the shift member of the front wheel transmission is severed, the front wheel transmission can be operated reliably. It is now possible to return to the standard drive side and maintain it, eliminating the need for the front wheels to be driven at increased speed when driving straight, making it possible to improve the running performance of the agricultural tractor.

〔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. 6, 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 an axle.

Next, the power transmission system and front wheel transmission 10 of the agricultural tractor will be described in detail. As shown in FIGS. The transmission is transmitted to the main transmission and auxiliary transmission (not shown above) in the output shaft 12 for gear change operation, and transmitted from the output shaft 12 to the rear wheel differential mechanism 2a.
The power branched from the second gear 12a is sent to the front wheel transmission 10 via the gear 13, and the speed is changed.
It is configured to be sent from the front wheel output shaft 15 to the front wheel differential mechanism 1a.

Next, the front wheel transmission 10 will be described in detail. As shown in FIG. They are interlocking. Then, both the first passive gear 16 that meshes with the gear 14a and the second passive gear 17 that meshes with the gear 14c fixed to the other end of the transmission shaft 14 are loosely fitted onto the front wheel output shaft 15. 1st and 2nd
A shift member 18 is mounted between the passive gears 16 and 17 with a spline structure so as to rotate integrally with the front wheel output shaft 15 and to be slidable in the axial direction.

This shift member 18 has claw-shaped engaging portions 18a and 18b at the front and rear in the shift direction.
A, 18b are engaged with and disengaged from the engagement portions 16a, 17a of the first and second driven gears 16, 17, thereby creating an engagement type first clutch 19 between the shift member 18 and the first driven gear 16. A second clutch 20 of an engaging type is constructed between the shift member 18 and the second passive gear 17. And the first
The clutch 19 is provided with a rubber ring 21 that absorbs shock during occlusion.

With the above structure, when the shift member 18 is engaged with the first passive gear 16, the power from the output shaft 12 is transmitted to the front wheels 1, 1 and the rear wheels via the gears 13, 14a, the first passive gear 16, and the shift member 18. 2 and 2 are driven at approximately the same speed in the standard drive state, the front wheel output shaft 1
5. Then, the shift member 18 is moved to the second position.
When engaged with the passive gear 17, the power is transferred to the gears 13 and 1.
4b, transmission shaft 14, gear 14c, second passive gear 1
7. The front wheels 1, 1 are transmitted to the front wheel output shaft 15 via the shift member 18 in an accelerated driving state in which the front wheels 1, 1 are driven at a higher speed than the rear wheels 2, 2.

Next, the operating system of the shift member 18 will be described in detail. As shown in FIG. 1, the front wheel output shaft 1
The shifter 22 of the shift member 18 is attached to the support shaft 28 so as to be movable in parallel with the front wheel output shaft 15, and the operating section 23 for sliding the shifter 22 in the axial direction is moved below the front wheel output shaft 15 in a direction perpendicular to the front wheel output shaft 15. The operating portion 23 is freely fitted onto the supported operating shaft 24 and attached to the standard drive side (the first clutch 19 entry side where the shift member 18 engages with the first passive gear 16) by the helical spring 25. It is strong.

Next, the switching mechanism 29 for linking the operating section 23 and the operating shaft 24 operated from outside the device will be described in detail.As shown in FIG.
A spline portion 23a is provided at the end of the boss portion of the shift member 26, which is fitted onto the spline portion 23a.
The spline part 2 fixed to the end of the operating shaft 24
4a so that the operating portion 23 and the operating shaft 24 rotate together. And the human operating tool 27
By rotating the operating shaft 24 around the axis by stepping on the handbrake pedal, which is an example, the shift member 18 is moved to the speed-increasing drive side (the shift member 18 engages with the second passive gear 17). 2 clutch to the 20 entry side). In addition, operation axis 2
As shown in FIG. 5, the spline portion 24a of No. 4 is
The tip of each tooth of the shift member 26 is formed into a tapered shape.
This ensures that the occlusal operation is performed smoothly.

Next, the linkage mechanism between the side brake pedals 27, 27 and the operating shaft 24 will be described in detail. As shown in FIG.
Lever arms 27a, 2 are attached to each of the support boss portions 7
7a is erected, and both lever arms 27a, 27
a U-shaped member 34 that has elongated holes 37, 37 as shown in the figure, inserts a pin 33 through both elongated holes 37, 37, and supports both ends of this pin 33; The operating lever 24b at the end of the operating shaft 24 shown in FIGS. 1 and 2 is interlocked and connected via a release wire 35 and a return spring 36. Further, the operating shaft 24 is biased toward the standard drive side by a helical spring 38, and is prevented from rotating further from the standard drive side by a stopper 39 and a roll pin 40.

Next, the operation system of the switching mechanism 29 will be described in detail. As shown in _FIGS . An L-shaped operating member 31 is supported on the boss portion 30 so as to be rotatable around a horizontal axis _P2 in the longitudinal direction of the fuselage, and one end of this operating member 31 is attached to the upper part of the shift member 26 of the switching mechanism 29. It is inserted into the provided recess. When this operating member 31 is rotated around the horizontal axis _P2 , the switching mechanism 29
The shift member 26 engages with the spline portion 24a of the operating shaft 24, and the handbrake pedal 2
7 and 27 and the shift member 18 of the front wheel transmission 10 are in a linked state, and the front wheel transmission 10 is automatically operated to the speed increasing drive side by depressing the handbrake pedal 27 on one side.

Next, when the shift member 26 is released from the spline portion 24a and operated, the above-mentioned hand brake pedal 2
The linkage state with 7 and 27 is canceled. By rotating and holding the operating member 31 around the horizontal axis P ₁ , the shift member 1 of the front wheel transmission 10 is rotated and held.
8 can be operated to the standard drive side, the speed-up drive side, and the neutral rear two-wheel drive position. Incidentally, as shown in FIG. 4, the shift member 26 is equipped with a ball detent mechanism 32.
6 is reliably maintained in the linked and unlinked states.

[Brief explanation of drawings]

The drawings show an embodiment of the front wheel transmission operation structure for an agricultural tractor according to the present invention, FIG. 1 is a front view of the operation system in the front wheel transmission, and FIG. 2 is a diagram showing the state of cooperation between the human operating tool and the front wheel transmission. , FIG. 3 is a side view of the front wheel transmission, FIG. 4 is a vertical cross-sectional side view of the operating member and the shift member in the switching mechanism, and FIG. 5 is a partially enlarged side view of the spline part in the switching mechanism.
FIG. 6 is an overall side view of the agricultural tractor. 1...Front wheel, 10...Front wheel transmission, 18...
Shift member, 19...first clutch, 20...second clutch, 27...human operating tool, 29...switching mechanism.

Claims (1)

[Claims] 1 Switch the transmission system to the steerable front wheels 1, 1 between a standard drive state in which transmission is performed 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 shift operation structure for an agricultural tractor equipped with a clutch-type front wheel transmission 10, in which a first clutch 19 of a standard drive system and a second clutch 20 of an increased speed drive system of the front wheel transmission 10 are connected to a shift member 18. The manual operation tool 27 and the shift member 18 of the front wheel transmission 10 are configured to be selectively engaged by forward and reverse operation of the
This front wheel gear shift operation structure for an agricultural tractor is provided with a switching mechanism 29 for switching between a linked state and a non-linked state, and the switching mechanism 29 biases a linkage system on a front wheel transmission 10 side to a standard drive side.