JPH0764215B2 - Front-wheel speed-up mechanism for 4-wheel drive tractor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a mechanism for increasing the drive rotation of only the front wheels in order to reasonably reduce the turning radius when the tractor is traveling around the field end. is there.

(B) Conventional Technology Conventionally, a technology for increasing the peripheral speed of the front wheels only when traveling around the field edge has been known.

For example, it is as described in JP-A-54-120138.

Further, as a mechanism for releasing the front wheel acceleration at a high speed of the sub-speed change, a technique as disclosed in JP-A-62-55226 is known.

(C) Problems to be solved by the invention In the front wheel speed increasing mechanism, the steering handle 6 has a certain degree or more,
For example, when operating at a cutting angle of 40 degrees or more, the speed is automatically switched.

Conventionally, the steering handle 6 and the speed increasing mechanism are linked hydraulically, or a wire is extended from the steering bell crank of the front wheel or the knuckle arm for feedback.

However, since the feedback path is long, the front wheels are not sufficiently accelerated due to the fact that they do not react sensitively to the rotation of the steering wheel 6, trouble occurs in the feedback mechanism, or backlash occurs. Is.

In the present invention, the feedback of the angle of the steering wheel 6 is directly linked to the speed increasing switching arm 9 from the pitman arm 7 via a link mechanism.

Further, in the link mechanism from the pitman arm 7 to the speed increasing switching arm 9, a speed increasing switching releasing mechanism is provided.

By providing the speed increase switching release mechanism, the front wheel speed increasing mechanism can be released because there is a risk of rollover when a front loader is attached to the front part of the tractor or when traveling at high speed on the road. It is a thing.

(D) Means for Solving the Problems The object of the present invention is as described above, and a configuration for achieving the object will be described below.

The front wheel F is linked to the steering operation of the steering wheel 6.
In a tractor provided with a mechanism for accelerating the drive rotation to the vehicle, an adjustment link 40, a bell crank 41, and a push link 42 are provided between the pitman arm 7 and the speed increase switching arm 9 which are rotated by operating the steering handle 6. The bell crank 41 is pivotally supported on a bell crank shaft 45 protruding from the body side of the tractor, an engaging pin 44 is projectingly provided at one end of the bell crank 41, and the engaging pin is operated by operating the steering handle 6. The speed increasing switching arm 9 is configured to be rotated by pushing the triangular engaging plate 50 fixed to one end of the push link 42 by rotating 44, and the triangular engaging plate 50 is mounted on the bell crank shaft 45. It is loosely fitted in the portion of the long hole 50a to enable movement of the bell crank shaft 45 in the axial direction and movement of the push link 42, and the triangular engaging plate 50 is further moved by the return spring 46 on the bell crank shaft 45. Attach in the direction to engage the engagement pin 44. Are, the release lever 47 provided pivotally on the body side of the tractor, triangular engaging plate on the bell crank shaft 45 by the rotation of the release lever 47
The triangular engagement plate 50 and the engagement pin 44 can be disengaged by sliding 50.

(E) Embodiment The object and structure of the present invention are as described above, and the structure of the embodiment shown in the accompanying drawings will be described below.

FIG. 1 is an overall side view of a four-wheel drive tractor.

It is composed of a front wheel F and a rear wheel R, and the front wheel F can be switched between driving and non-driving by operating a front wheel driving clutch lever.

The driving force of the front wheels F is transmitted from the inside of the transmission case M for driving the rear wheels to the front differential case 52 through the take-out gear case D and the front wheel power transmission shaft device 51.

A front axle bracket 37 projects from the front of the engine, and a clutch housing on the rear of the engine.
38 are fixed. A steering box 39 is arranged on the upper surface of the clutch housing 38, and a transmission case M is attached to the rear surface of the clutch housing 38.

According to the present invention, when the steering handle 6 is rotated for steering at a certain angle or more, the number of rotations of the front wheel F is automatically increased, and the turning operation at the field end of the tractor is performed at the turning radius. The present invention relates to a front wheel speed-increasing mechanism for a four-wheel drive tractor, which is configured to be small.

With the rotation of the steering wheel 6, the pitman arm 7 rotates back and forth via the steering box 39,
The steering bell crank 8 is rotated by the drag rod 35 connected to the pitman arm 7.

2 is a side sectional view of a portion of the transmission case M and the take-out gear case D, and FIG. 3 is a front sectional view of the front wheel speed increasing / switching portion,
FIG. 4 is a plan sectional view of the same.

A power transmission mechanism for driving the front wheels will be described with reference to FIG.

The power of the engine is transmitted to the auxiliary transmission shaft 3. A traveling auxiliary speed change is performed between the auxiliary speed change shaft 3 and the pinion shaft 2.

Further, below the pinion shaft 2 and the auxiliary transmission shaft 3, the PTO transmission shaft 1
0 has passed, and a speed increasing switching mechanism is formed on the front wheel speed increasing cylindrical shaft 5 that is loosely fitted to the outer periphery of the PTO transmission shaft 10. Then, the power is transmitted to the front wheel power transmission shaft device 51 (FIG. 1) in front of the take-out gear case D protruding to the bottom surface of the mission case M.

First, the traveling auxiliary shift between the auxiliary shift shaft 3 and the pinion shaft 2 will be described.

The fixed gears 14, 13, 12 are arranged on the sub transmission shaft 3,
The fixed gears 14 and 12 are in constant mesh with the loosely fitting gears 17 and 16 on the pinion shaft 2.

A sliding gear 15 slidably engaged with the engaging spline cylinder 18 on the pinion shaft 2 is meshable with a fixed gear 13, and a loosely fitted gear on the pinion shaft 2 is further provided.
It is possible to engage with 17, 16 locking claws.

Therefore, by sliding the sliding gear 15 to three positions, three stages of traveling auxiliary shift can be obtained.

The sliding gear 15 slides to the right, and at the position of 15c, the loose fitting gear 1
By engaging with the claws of 6, fixed gear 12 → loose fitting gear 16
→ Sliding gear 15 → engagement spline cylinder 18 → Power is transmitted to the pinion shaft 2 to obtain a low speed.

Next, when the sliding gear 15 meshes with the fixed gear 13 at the position 15b, the fixed gear 13 → sliding gear 15 → engaging spline cylinder
18 → Power is transmitted to the pinion shaft 2 and medium speed is obtained.

Next, the sliding gear 15 is engaged with the claw of the loose fitting gear 17 at the position of 15a, so that the fixed gear 14 → the loose fitting gear 17 → the sliding gear 15
→ Engagement spline cylinder 18 → Power is transmitted to the pinion shaft 2 and high speed is obtained.

A pinion gear 19 is engraved on the rear end of the pinion shaft 2 to transmit power to the differential gear device. The rotations of the low, middle, and high auxiliary shifts are transferred from the fixed gear 20 on the pinion shaft 2 to the sliding gear 22 loosely fitted on the front wheel speed increasing cylinder shaft 5 → the fixed gear 21 → the front wheel drive shaft. 1 through the clutch sliding gear 25,
It is transmitted to the front wheel F.

Slide the clutch sliding gear 25 back and forth to
By connecting / disconnecting the meshing state with the 21, it is possible to switch between driving and non-driving the front wheels.

Only with the power transmission mechanism, only the rotation proportional to the rotation of the pinion shaft 2 can be taken out to the front wheel drive shaft 1. However, in the present invention, in order to reduce the turning radius at the field end, the clutch is used. The rotation of the sliding gear 25 is a fixed gear
The rotation speed is higher than that of 21 rotations.

That is, in the case of normal four-wheel drive, the rotation speed of the front wheel F is slightly faster than the rotation of the rear wheel. In this case, the fixed gear 20 to the sliding gear 22 on the pinion shaft 2 are rotated. Through
The power is transmitted to the fixed gear 21 connected by the locking claws, and the power is transmitted to the clutch sliding gear 25.

On the other hand, when the speed is increased in order to reduce the turning radius, the front wheel F is rotated at about twice the speed of the rear wheel R. In this case, power is transmitted from the sliding gear 15 on the pinion shaft 2 to the loose fitting gear 24 on the front wheel speed increasing cylinder shaft 15, and the speed increasing clutch 4 and the one-way clutch C are transmitted from the loose fitting gear 24. Is transmitted to the front wheel speed-increasing cylinder shaft 5 and is transmitted from the front wheel speed-increasing cylinder shaft 5 to the clutch sliding gear 25 on the front wheel drive shaft 1 via the fixed gear 21.

The above-described speed-up drive and normal drive are automatically switched by the turning angle of the steering wheel 6.

That is, when the turning angle of the steering handle 6 exceeds approximately 40 degrees, the shift forks 30, 3 are moved through the arm shaft 27.
It rotates by rotating 1 at the same time.

The sliding fork 30 slides the sliding gear 22 back and forth, the shift fork 31 slides the clutch pressing body 23 of the speed increasing clutch 4 back and forth, and both slides are performed at the same time. The sliding gear 22 and the clutch pressing body 23 may be slid integrally, but since the intermediate wall 26 of the mission case M is disposed between them, the intermediate wall 26
It is configured to operate both before and after simultaneously.

The sliding gear 22 is engaged / disengaged with the fixed gear 21 in front of the sliding gear 22, and the clutch pressing body 23 presses / non-presses the friction plate of the speed increasing clutch 4 to reversely generate power. They are connected and disconnected.

However, in order to increase the speed of the front wheels F at the high speed of the sub-shift,
Since the direction of the front wheels F suddenly turns to the side at high speed, the machine body may roll over. In FIG. 2, it is configured such that the speed-up drive cannot be performed at the high speed of the auxiliary shift.

That is, the sliding gear 15 has a low speed position 15c, a neutral position 15,
It is possible to take four positions, a medium speed position 15b and a high speed position 15a, but at the position of 15a which is the auxiliary shift high speed position, the sliding gear 15 is not in mesh with the loose fitting gear 24. Next to
The power is not transmitted to the front wheels F even when switching to the speed-up drive side.

That is, while the front-wheel drive clutch is engaged, and the steering wheel 6 is being shifted at a high speed of the auxiliary shift,
When a cutting angle of 40 degrees or more is operated, the speed is not increased and the front wheels are not driven.

Even when the aircraft is moving backward, if the speed is increased, the rear part of the tractor will rotate more than usual and a dangerous situation will occur.Therefore, in this configuration, the traveling speed is set to reverse. In this case, the one-way clutch C is interposed between the speed increasing clutch 4 and the front wheel speed increasing tsu shaft 5 so that the speed increasing drive is not performed.

When the traveling speed is forward, the one-way clutch C rotates integrally with the inner diameter portion of the speed increasing clutch 4 and the front wheel speed increasing cylindrical shaft 5, but when the main speed is changed to the reverse position, the sub speed change Is reversely rotated and both the loosely fitted gear 24 and the speed increasing clutch 4 are reversely rotated. Therefore, the speed increasing clutch 4 and the front wheel speed increasing cylinder shaft 5 are loosely fitted, and power is not transmitted. When it exceeds the maximum, the front wheel drive state is cut off.

Next, the movement of the shift forks 30, 31 due to the rotation of the speed increasing switching arm 9 will be described with reference to FIGS. 3 and 4.

The speed-increasing switching arm 9 is interlocked with the steering handle 6 and rotates when the steering angle exceeds a certain angle, and the arm shaft 27 on which the speed-increasing switching arm 9 is fixed is inserted into the mission case M. Has been done.

The shifter arm 34 is fixedly mounted on the arm shaft 27, and the shifter arm 34 is provided at different positions a and b from the arm shaft 27 of the shifter arm 34.
Book pins 32 and 33 are planted. The pins 32 and 33 are engaged with the shift forks 30 and 31, respectively.

That is, the pin 32 having a long arm length is engaged with the shift fork 30 that slides the sliding gear 22, and the clutch pressing body 23
The pin 33 having a short arm length is engaged with the shift fork 31 that slides.

With this configuration, when the shifter arm 34 rotates, the distances a and b
Corresponding to, the pinion shaft 2 slides a distance A, and the clutch pressing body 23 slides a distance B.

The distances A and B are configured so that the half-engagement state of the speed increasing clutch 4 occurs before the sliding gear 22 and the fixed gear 21 are disengaged from each other, and the power transmission states of the two overlap. This prevents the situation in which the four-wheel drive is momentarily switched to the two-wheel drive when the normal drive is switched to the speed-up drive.

FIG. 5 is a side view of the steering handle 6 and the front axle bracket 37, FIG. 6 is a plan view of the same, and FIG. 7 is a side view showing the interlocking state of the pitman arm 7 and the speed increasing switching arm 9; FIG. 9 is a plan view of the same, FIG. 9 is a side view of the speed increase switching release mechanism, and FIG. 10 is a plan view of the same.

5 and 6 will be described.

A steering box 39 is placed on the clutch housing 38, and a steering handle 6 projects from the steering box 39. The rotation of the steering handle 6 causes the pitman arm 7 protruding from the steering box 39 to rotate back and forth.

Conventionally, the drag rod 35 was connected to the steering bell crank 8 ahead of the pitman arm 7, but in this configuration,
The adjusting link 40 and the pushing link 42 are provided toward the speed increasing switching arm 9 protruding from the mission case M.

Tie rods 36, 36 are connected and supported at the other end of the steering bell crank 8 supported at the center of the front axle bracket 37.

The front ends of the tie rods 36, 36 are connected to a knuckle arm to steer and rotate the front wheel F.

Next, referring to FIG. 7 and FIG. 8, a structure in which the speed increase switching release mechanism is not attached will be described.

The drag rod 35 is pivotally connected to the pitman arm 7, and the adjustment link 40 is pivotally connected to the pitman arm 7 as in the case of the drag rod 35.

The adjusting link 40 is provided with a turnbuckle mechanism so that the turning angle of the steering handle 6 can be adjusted to change between the speed-up drive and the normal drive.

The adjusting link 40 is pivotally connected to one end of a bell crank 41 which is pivotally supported by the airframe. A push link 42 is provided at the other end of the bell crank 41, and the push link 42 is connected to the speed increasing switching arm 9.

The push link 42 is branched into a front push link 42a and a rear push link 42b, and a slide cylinder 42c is interposed in the center. In the portion of the slide cylinder 42c, when the turning angle of the steering handle 6 is 40 degrees or less of the speed increase switching angle, the sliding of the front push link 42a is absorbed.

The biasing spring 55 biases and biases the rear push link 42b forward.

Next, referring to FIG. 9 and FIG. 10, the structure provided with the speed increase switching release mechanism will be described.

The mechanism is configured so that the speed increase switching is not performed even if the steering handle 6 is rotated beyond a certain turning angle.

For this purpose, the bell crank 41 and the push link 42 are disengaged from each other.

That is, the triangular engaging plate 50 is fixedly provided at the front end of the front push link 42a, and the triangular engaging plate 50 and the engaging pin 44 provided at one end of the bell crank 41 are engaged with each other, whereby the speed increase switching is performed. It is configured to be viewed.

When the engagement pin 44 and the triangular engagement plate 50 are not engaged with each other, a mechanism for releasing the speed-up switching is provided so as not to be performed.

A release lever 47 is pivotally supported on the body side of the tractor, and a release pin 48 is provided at the tip of the release lever 47.

The release lever 47 is extended through a wire or a link to a position where an operator in the driver's seat can easily operate.

Therefore, when the release lever 47 is rotated, the release pin 48 moves outward, and the bell crank shaft 45 of the bell crank 41 has a long hole 50a.
The triangular engaging plate 50 that is loosely fitted in the above portion and is slidable outward is pushed out. This allows the triangular engaging plate
50 moves outward on the bell crankshaft 45, and the engaging pin 44
Even if is rotated, it will not contact the triangular engagement plate 50.
As a result, the speed increase switching release is not performed.

In order to return the speed increase switching release, the release lever 47 is returned to the original position, and the return spring 46 on the bell crank shaft 45 returns the triangular engaging plate 50 to the original position.

(G) Effects of the Invention Since the present invention is configured as described above, it has the following effects.

First, in the present invention, the triangular engaging plate 50 is set to the release lever.
Since the engagement with the engagement pin 44 is released by sliding the bell crankshaft 45 by 47, the engagement pin 44 and the triangular engagement plate 50, which are absolutely necessary, can be used as they are in the release mechanism. It became possible to use it for both.

Second, the bell crank shaft 45 that pivotally supports the bell crank 41
Since the part of the long hole 50a of the triangular engaging plate 50 is loosely fitted, the bell crank shaft 45 can be used as a guide part for sliding the triangular engaging plate 50, and also as an interposing part of the return spring 46. I was able to use it in combination.

Thirdly, since the transmission link, the bell crank 41, and the triangular engaging plate 50 are interlocked between the pitman arm 7 and the speed increasing switching arm 9 protruding from the mission case M immediately behind the pitman arm 7, there is little rattling. Moreover, the arrangement of piping such as hydraulic pressure is not necessary, and the responsiveness is improved.

Fourth, since a speed-up switching release mechanism could be provided between the pitman arm 7 and the speed-up switching arm 9, the wire is extended from that portion to the operator's position and remotely operated to release the speed-up switching. The mechanism is easier.

Fifth, the adjustment link 40 allows fine adjustment in the vicinity of the cutting angle of 40 degrees, and the adjustment can be made at a position where the side of the mission case M can be easily adjusted.

[Brief description of drawings]

FIG. 1 is an overall side view of a four-wheel drive tractor, FIG. 2 is a side sectional view of a portion of a transmission case M and a take-out gear case D, FIG. 3 is a front sectional view of a front wheel speed increasing switching portion, and FIG. Similarly, FIG. 5 is a side view of the steering handle 6 and the front axle bracket 37, FIG. 6 is a plan view of the same, and FIG. 7 shows the interlocking state of the pitman arm 7 and the speed increasing switching arm 9. A side view, FIG. 8 is a plan view of the same, FIG. 9 is a side view of the speed-increasing switching release mechanism, and FIG. 10 is a plan view of the same. 6 ... Steering handle 7 ... Pitman arm 9 ... Acceleration switching arm 40 ... Adjustment link 41 ... Bell crank 42 ... Push link 42a ... Front push link 42b ... Rear push link 42c ... … Slide cylinder 44 …… Engagement pin 47 …… Release lever 48 …… Release pin 50 …… Triangular engagement plate

Claims (1)

[Claims] 1. A tractor provided with a mechanism for increasing the driving rotation of the front wheels F in conjunction with the steering operation of the steering handle 6, and the pitman arm 7 and the speed increased by the operation of the steering handle 6. The switching arms 9 are connected to each other by an adjusting link 40, a bell crank 41 and a pushing link 42, and the bell crank 41 is pivotally supported on a bell crank shaft 45 protruding from the body side of the tractor, and one end of the bell crank 41 is connected. An engaging pin 44 is projected on the steering pin 6, and the engaging pin 44 is rotated by the operation of the steering handle 6 to push the triangular engaging plate 50 fixed to one end of the push link 42 to rotate the speed increasing switching arm 9. The triangular engagement plate 50 is loosely fitted on the bell crank shaft 45 at the portion of the elongated hole 50a to move the bell crank shaft 45 in the axial direction and the push link 42. The triangular engaging plate 50 It is urged by a return spring 46 on the crankshaft 45 in a direction to engage with the engagement pin 44, and is pivotally supported on the body side of the tractor to provide a release lever 47. Sliding the triangular engaging plate 50 on the shaft 45, the triangular engaging plate 50 and the engaging pin
A front wheel speed-increasing mechanism for a four-wheel drive tractor characterized in that the engagement of 44 can be released.