JPS63306922A - Front wheel speed-increasing mechanism for four-wheel-drive tractor - Google Patents

Abstract

PURPOSE:To prevent a tractor from turning sideways, by increasing a speed of the front wheel only when the tractor is in low speed running so as to avoid its rapid turn when the tractor is in high speed running, in case of the tractor which increases the speed of the front wheel being associated with a steering handle so as to less decrease a radius of turning. CONSTITUTION:A tractor provides a power take off (PTO) transmitting shaft 10 to be arranged in the bottom of a pinion shaft 2 and a subspeed change shaft 3 further a speed increase switching mechanism to be arranged on a front wheel speed increase cylinder shaft 5 externally fitted to the PTO transmitting shaft 10. When speed of the front wheel is increased to decrease the radius of turning, the tractor, driving an arm shaft 27 by a steering handle, transmits power, after it is transmitted to an idly fitted gear 24 on the cylinder shaft 5 from a sliding gear 15 on the pinion shaft 2, to a sliding gear 25 on the front wheel driving shaft 1 through a speed increasing clutch 4, one-way clutch C and a fixed gear 21. The tractor sets the sliding gear 15 and the idly fitted gear 24 to disengaging condition in the high speed position of subspeed change, and power is released from being transmitted to the front wheel.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field The present invention relates to a mechanism that increases the drive rotation speed of only the front wheels in order to reasonably reduce the turning radius when a tractor turns around the edge of a field. be.

(B) Prior Art Conventionally, a technique has been known to increase the circumferential speed of the front wheels only when turning around at the edge of the field.

For example, Japanese Patent Laid-Open No. 120138/1983.

(c) Problems to be Solved by the Invention However, the front wheel speed increasing mechanism automatically switches to speed increasing when the steering wheel 6 is operated at a turning angle of approximately 40 degrees or more; Regardless of whether the vehicle was traveling at low or high speed, the switching operation to increase the speed was performed regardless of the vehicle's traveling speed.

Therefore, when doing work such as plowing or puddling in the field, the speed is always low, so there is no danger even if the front wheels are driven at increased speed.On the other hand, turning in a small radius improves work efficiency. be.

However, when driving on the road or in four-wheel drive mode to improve traction while driving on a slope, when a sharp curve is reached and an attempt is made to turn, the front wheel acceleration drive mechanism is activated and the front wheels suddenly turn sharply. This caused an accident in which the speeding tractor overturned and injured the operator.

The present invention is configured to prevent the front wheels from being driven at increased speed during high-speed driving.

(d) Means for Solving the Problems The objects of the present invention are as described above. Next, the structure for achieving the objects will be explained.

In a tractor equipped with a mechanism that increases the drive rotation to the front wheels F in conjunction with the turning operation of the steering handle 6, the front wheel speed increase switching is activated only when the traveling speed is low, and when the traveling speed is high. The structure is such that the front wheel speed increase switching does not operate.

Further, the driving force for increasing the speed of the front wheels is transmitted from the sliding gear 15 for driving the sub-speed change operation via the loosely fitted gear 24 and the speed increasing clutch 4, and by the engagement of the speed increasing clutch 4, the front wheel power transmission shaft It is configured to transmit power to the device 51, and is configured so that the sliding gear 15 and the loosely fitted gear 24 mesh only when the sliding gear 15 slides to a low speed position.

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

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 drive clutch lever.

Further, the driving force for the front wheels F is transmitted from inside the Mitsushiran case M for driving the rear wheels to the front differential case 52 via the extraction gear case D and the front wheel power transmission shaft device 51.

A front axle bracket 37 is exposed in front of the engine, and a clutch housing 38 is fixed to the rear of the engine. A steering box 39 is arranged on the upper surface of the clutch housing 38, and a Mitsushiran 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 by more than a certain angle, the rotational speed of the front wheels F is automatically increased to reduce the turning radius when the tractor is opened at the edge of the field. The present invention relates to a front wheel speed increasing mechanism for a four-wheel drive tractor, which is configured to perform a four-wheel drive tractor.

As the steering handle 6 rotates, the pitman arm 7 rotates back and forth via the steering box 39, and a drag rod 35 connected to the pitman arm 7 rotates the steering bell crank 8.

Figure 2 is a side sectional view of the transmission case M and extraction gear case D, Figure 3 is a front sectional view of the front wheel speed increase switching section,
FIG. 4 is the same (plan sectional view).

Referring to FIG. 2, the power transmission mechanism for front wheel drive will be explained.

The driving sub-shift is performed between the sub-transmission shaft 3 and the pinion shaft 2, to which engine power is transmitted.

In addition, a PTO transmission shaft 1O passes below the pinion shaft 2 and the auxiliary transmission shaft 3, and a speed increase switching mechanism is configured. The front wheel power transmission shaft device 1!51 is located in front of the take-out gear case D protruding from the bottom of the mission case M.
Power is transmitted to (Figure 1).

First, the traveling sub-shift between the sub-shift shaft 3 and the pinion shaft 2 will be explained.

Fixed gears 14, 13, and 12 are arranged on the sub-transmission shaft 3, and 14 and 12 among the fixed gears are connected to the pinion shaft 2.
It is always meshed with the loosely fitted gears 17 and 16 above.

Further, a sliding gear 15 which is slidably engaged with a spline on an engagement spline tube 18 on the pinion shaft 2 can mesh with the fixed gear 13, and a loosely fitted gear 17 on the pinion shaft 2. It is possible to engage with 16 locking claws.

Therefore, by sliding the sliding gear 15 to the third position, three stages of the travel sub-speed can be obtained.

The sliding gear 15 slides to the right and meshes with the pawl of the loosely fitted gear 16 at the position 15c, so that the fixed gear 12 -> loosely fitted gear 16 - sliding gear 15 - engaging spline cylinder 18 - Power is transmitted to the pinion shaft 2, resulting in low speed.

Next, the sliding gear 15 meshes with the fixed gear 13 at the position 15b, and power is transmitted from the fixed gear 13 to the sliding gear 15 to the engagement spline tube 18 to the pinion shaft 2, and the medium speed is increased. can get.

Next, the sliding gear 15 engages with the pawl of the loosely fitted gear 17 at the position 15a, so that the fixed gear 14 → the loosely fitted gear 17 →
Power is transmitted between the sliding gear 15, the engaging spline cylinder 18, and the pinion shaft 2, resulting in high speed.

A pinion gear 19 is engraved on the rear end of the pinion shaft 2, and transmits power to the differential gear device.
The rotation of the medium and high auxiliary gears is controlled by the fixed gear 2 on the pinion shaft 2.
0, the sliding gear 22- loosely fitted on the front wheel speed-increasing cylinder shaft 5
Fixed gear 21 - clutch sliding gear 25 on front wheel drive shaft 1
It is transmitted to the front wheels F via.

By sliding the clutch sliding gear 25 back and forth to engage/disengage the fixed gear 21, the front wheels can be switched between driving and non-driving.

This is because the power transmission mechanism alone can only output a rotation proportional to the rotation of the pinion shaft 2 to the front wheel drive shaft 1, but in the present invention, in order to reduce the turning radius at the edge of the field, the clutch The structure is such that the rotation of the sliding gear 25 can be made faster than the rotation of the fixed gear 21.

That is, in the case of normal four-wheel drive, the rotation speed of the front wheels F is slightly faster than the rotation of the rear wheels. Power is transmitted to the fixed gear 21 connected by a locking pawl,
Power is transmitted to the clutch sliding gear 25.

On the other hand, when speeding up to reduce the turning radius, the front wheels F rotate at about twice the speed of the rear wheels R. In this case, the sliding gear 15 on the pinion shaft 2
The power is transmitted to the loosely fitted gear 24 on the front wheel speed increasing cylinder shaft 5, and is transmitted from the loosely fitting gear 24 to the front wheel speed increasing cylinder shaft 5 via the speed increasing clutch 4 and the one-way latch C. Power is transmitted from the front wheel speed increasing cylinder shaft 5 via a fixed gear 21 to a clutch sliding gear 25 on the front wheel drive shaft 1.

The above-mentioned switching between the speed-up drive and the normal drive is automatically performed by changing the turning angle of the spooling handle 6.

That is, the shift forks 30 and 31 are simultaneously rotated via the arm shaft 27 depending on the turning angle of the steering handle 6.

The shift fork 30 slides the sliding gear 22 back and forth, and the shift fork 31 slides the clutch pressing body 23 of the speed increasing clutch 4 back and forth, and both slide simultaneously.

The sliding gear 22 and the clutch pressing body 23 may be integrated and slid together, but since the intermediate wall 26 of the Mitsushiran case M is placed between them, it is possible to slide the two parts separated into the front and rear of the intermediate wall 26. At the same time, it should be constructed.

The sliding gear 22 engages and disengages with the fixed gear 21 at the front, and the clutch pressing body 23 engages and disengages the fixed gear 21 .
By pressing and not pressing the friction plate, the power is reversely traversed.

However, rotating the front wheel F at increased speed at the high speed of the sub-shift,
At high speeds, the direction of the front wheels F suddenly changes to the side, which may cause the aircraft to roll over.As shown in Fig. 2, the configuration is such that increased speed drive is not possible at high speeds during the sub-shift.

That is, the sliding gear 15 has a low speed position 15c and a neutral position 1.
5, medium speed position 15b, and high speed position 15a, but in position 15a, which is the high speed position of the sub-shift, the sliding gear 15 does not mesh with the loosely fitted gear 24. condition, and even if the switch is made to the speed-increasing drive side, the front wheel F
It is constructed so that no power is transmitted to the

In other words, if the steering wheel 6 is turned more than a certain angle while the front wheel drive clutch is engaged and the auxiliary gear is shifting at a high speed, the front wheels will not be driven and the front wheels will not be driven. It is what it is.

In addition, even when the machine is moving backwards, if the speed is increased, the rear of the tractor will rotate more than usual, creating a dangerous situation. In order to avoid accelerating drive when
A one-way latch C is interposed between the speed increasing clutch 4 and the front wheel speed increasing cylinder shaft 5.

When the traveling speed is forward, the one-way clutch C rotates by integrating the inner diameter part of the speed increasing clutch 4 and the front wheel speed increasing cylinder shaft 5, but when the speed is changed to the reverse position during the main speed change part, the auxiliary speed change occurs. All rotations are reverse rotation, and the loosely fitted gear 24 is also connected to the speed increasing clutch 4.
Since the speed increasing clutch 4 and the front wheel speed increasing cylinder shaft 5 also rotate in the opposite direction,
During this period, there is a loose fit and no power is transmitted, and when the steering wheel 6 is turned significantly, the front wheel drive state is discontinued.

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

The speed increase switching arm 9 rotates in conjunction with the steering handle 6 when it reaches a certain angle plate, and the arm shaft 27 to which the speed increase switching arm 9 is fixed is located inside the transmission case M. It has been inserted.

A shifter arm 34 is fixed to the arm shaft 27, and the shifter arm 34 is fixed at different distances a-b from the arm shaft 27.
Two pins 32 and 33 are about to be implanted at the positions.

The pins 32 and 33 are engaged with the shift forks 30 and 31.

That is, the shift fork 3 that slides the sliding gear 22
A pin 32 with a longer arm length is engaged with the shift fork 31 that slides the clutch pressing body 23, and a pin 33 with a shorter arm length is engaged with the shift fork 31 that slides the clutch pressing body 23.

With this configuration, when the shifter arm 34 rotates, the distance 11
Corresponding to a-b, the pinion shaft 2 slides by a distance A, and the clutch pressing body 23 slides by a distance B.

The distance A-B is configured so that the speed-increasing clutch 4 is in a half-clutch state before the sliding gear 22 and the fixed gear 21 are disengaged, so that the power transmission states of both overlap. This prevents the occurrence of a situation in which four-wheel drive momentarily switches to two-wheel drive when switching from normal drive to speed-up drive.

FIG. 5 is a side view of the steering handle 6 and front axle bracket 37, FIG. 6 is a plan view,
Fig. 7 is a side view showing the interlocking state of the pitman arm 7 and the speed increase switching arm 9, Fig. 8 is a plan view of the same, Fig. 9 is a side view of the speed increase switch release mechanism, and Fig. 10 is a plan view of the same. It is.

Let me explain about Figures 5 and 6.

Steering box 3 on top of clutch housing 38
9 is placed thereon, and the steering handle 6 protrudes 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 has been connected to the steering bell crank 8 in front of the pitman arm 7, but in this configuration, the speed increasing switching arm protruding from the misosilane case M is connected to the pitman arm 7. 9
An adjustment link 40 and a push link 42 are interposed toward the front.

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

The tips of the tie rods 36 are connected to knuckle arms to steer and rotate the front wheels F.

Next, referring to FIGS. 7 and 8, a configuration in which a speed increase switching release mechanism is not provided will be described.

A drag rod 35 is pivotally connected to the pitman arm 7, and similarly to the drag rod 35, an adjustment link 40 is pivotally connected to the pitman arm 7.

A turnbuckle mechanism is interposed in the adjustment link 40 so that it is possible to adjust the angle at which the steering handle 6 is turned to switch between accelerated drive and normal drive.

The adjustment link 40 is pivotally connected to one end of a bell crank 41 that is pivotally supported on the fuselage. A push link 42 is interposed at the other end of the bell crank 41, and the push link 42 is connected to the speed increase 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. The slide cylinder 42c absorbs the sliding movement of the front push link 42a when the turning angle of the steering handle 6 is less than 40 degrees.

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

Next, referring to FIG. 9 and FIG. 1θ, the configuration in which the speed increase switching release mechanism is provided will be explained.

This mechanism is configured so that even if the squaring handle 6 is rotated to a certain angle, no speed increase switching is performed.

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

That is, a triangular engagement plate 50 is fixed to the front end of the front push link 42a, and the triangular engagement plate 50 engages with the retaining pin 44 provided at one end of the bell crank 41, thereby performing speed increase switching. It is configured in such a way that it is

A mechanism is provided to release the clutch pin 44 and the triangular engagement plate 50 so that the speed increase change is not performed.

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

Therefore, when the release lever 47 is rotated, the release pin 48 moves outward, and the triangular engagement plate 50 is loosely fitted into the bell crank shaft 45 of the bell crank 41 at the elongated hole 50a, making it possible to slide outward. It pushes out. As a result, the triangular engagement plate 50 moves outward on the bell crankshaft 45, and even if the engagement pin 44 rotates, it does not come into contact with the triangular engagement plate 50. This causes the speed increase switching to be canceled.

To release the speed increase switching, return the release lever 47 to its original position and release the return spring 4 on the bell crankshaft 45.
Step 6 is performed by returning the triangular engagement plate 50 to its original position.

The release lever 47 is extended by a wire or the like, and is placed at a position where it can be easily operated by the operator sitting on the seat.

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

First, when the tractor turns to change direction at the edge of the field, the circumferential speed of the front wheels F is increased by increasing the speed of the front wheels F, thereby making it possible to reduce the turning radius. In the stroke, the steering operation for turning the tilled row to an adjacent position can be performed without turning the steering handle 6 back.

Second, by increasing the circumferential speed of the front wheels F in a situation where the wheels slip in wet fields, the turning radius can be reliably reduced.

Thirdly, when driving on the road or on a slope, when using four-wheel drive to improve traction, if you approach a sharp curve and turn the steering wheel 6 greatly, the front wheel speed-up drive suddenly activates, causing the aircraft to There was a risk that the vehicle would start making sharp turns at high speeds and roll over, but in the present invention, this risk is eliminated because the system is configured so that switching to front-wheel high-speed drive is not performed at high speeds. We were able to resolve this issue.

Fourthly, power is transmitted from the sliding gear 15 of the auxiliary transmission via the loosely fitted gear 24 and the speed increasing clutch 4, and the loosely fitted gear 24 is structured so that the sliding gear 15 does not mesh at a high speed position, By creating the above-mentioned non-operating state during high-speed running, the gear can be used for multiple purposes, reducing the number of additional parts and improving functionality.

[Brief explanation of drawings]

Fig. 1 is an overall side view of the four-wheel drive tractor, Fig. 2 is a side sectional view of the transmission case M and extraction gear case D, Fig. 3 is a front sectional view of the front wheel speed increase switching section, and Fig. 4 is a side sectional view of the four-wheel drive tractor. 5 is a side view of the steering handle 6 and front axle bracket 370, FIG. 6 is a plan view, and FIG. 7 is a side view showing the interlocking state of the pitman arm 7 and the speed increase switching arm 9. FIG. 8 is a plan view, FIG. 9 is a side view of the speed increase switching release mechanism, and FIG. 1O is a plan view. l...Front wheel drive shaft 2...Pinion shaft 3...Sub-transmission shaft 4...Speed-up clutch 5...Front wheel speed-up cylinder shaft 6...Steering handle 15...Sliding gear 24 ...Playing gear

Claims (2)

[Claims] (1) In a tractor equipped with a mechanism that increases the speed of the drive rotation to the front wheels F in conjunction with the turning operation of the steering handle 6, the front wheel speed increase switching is activated only when the traveling speed is low, and the traveling speed is A front wheel speed increasing mechanism for a four-wheel drive tractor, characterized in that the front wheel speed increasing switching does not operate at high speeds. (2) The driving force for increasing the front wheel speed according to claim 1 is transmitted from the sliding gear 15 for operating the auxiliary speed change via the loosely fitted gear 24 and the speed increasing clutch 4. It is configured to transmit power to the front wheel power transmission shaft device 51 by engaging the speed clutch 4, and the sliding gear 15 and the loosely fitted gear 24 mesh only when the sliding gear 15 slides to the low speed position. A front wheel speed increasing mechanism for a four-wheel drive tractor, characterized in that it is configured as follows.