JPS6015709Y2 - 4-wheel drive switching device for agricultural tractors - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a four-wheel drive switching device that allows switching between a rear-wheel drive system and a four-wheel drive system for an agricultural tractor.

Generally, a four-wheel drive agricultural tractor is equipped with a power take-off part 2 (PTO case) for front wheel drive on the lower side of a transmission case 1, as shown in Fig. 1, and a switching fork that protrudes from the PTO case 2 in the vehicle width direction. A switching lever 4 is attached to the shaft 3.

This lever 4 passes behind the step 5 fixed to the transmission case 1 and stands up from the inside of the fender 6 toward the seat 7 side.

However, with this structure, the operator has to squat down to grasp the switching lever 4, making it difficult to operate.

In order to solve the above-mentioned conventional problems, the present invention is a foot-operated switching arm and has been improved so that a support bracket for the foot-operated switching arm can be easily obtained.

In Figure 1, the side of mission case 1 (front side)
A step 5 and a switching arm support bracket 10 are fixed together by tightening, and a support shaft 11 in the vehicle width direction (perpendicular to the paper plane of FIG. 1) is provided at the tip of the bracket 10 that protrudes upward from the step 5. , the switching arm 1 is attached to this support shaft 11.
A lever 13 fixed to the tip of the switching fork shaft 3 and the switching arm 12
are connected by a link 14.

15 is a clutch pedal, 16 is a main gear changeover lever, 1
7 is the rear wheel.

Further, 18 in FIG. 2 indicates the position of the left foot on step 5.

In FIG. 3, which shows a cross section taken along the line ■-■ in FIG. be.

The bracket 10 has a support shaft 11 at its upper end, and the switching arm 12 supported on the support shaft 11 has a pedal 22 (2) at its front end.
It also has a pedal 23 with a width of 14 integrally at the rear end.

As shown in Fig. 4, the bent portion of the upper end of the link 14 fits into the hole 24 made in the arm 12 slightly forward of the support shaft 11 (on the left side of the figure), and a cotter pin or the like is attached to the tip protruding from the hole 24. There is a stopper in place for removal.

The bent portion of the lower end of the link 14 is connected to the hole 25 at the tip of the lever 13.
It fits in the same way and has a stopper when removed.

A boss 26 at the base end of the lever 13 is fitted onto the switching fork shaft 3 and fixed in position by a pin 27.

As is clear from FIG. 5, a switching fork 28 is fixed to the tip of the shaft 3 protruding into the PTO case 2, and the tip of the fork 28 is engaged with an annular groove 30 of a sliding gear 29. .

In FIG. 4, the sliding gear 29 is fitted with a spline on the top of the three PTO shafts, and is fitted into two recesses 3 provided in the spline on the inner circumference.
A detent ball 34 is fitted into one of the recesses 32 by the elastic force of a spring 35, and holds the sliding gear 29 in an off position away from the PTO intermediate gear 36.

When the sliding gear 29 is moved to the right in FIG. 4 and the ball 34 is fitted into the recess 33, the gear 29 is held in the on position where it meshes with the gear 36.

The PTO shaft 31 is located forward from the PTO case 2 (left side in Figure 4)
It projects through the propeller shaft (not shown) and connects to the differential mechanism in the center of the front axle housing.

The case 2 is attached to the mission case 1 with a plurality of bolts so as to close the window hole 37 provided in the bottom wall of the mission case 1, and the PTO intermediate gear 36 is constantly engaged with the gear 39 on the drive shaft 38. , therefore, the intermediate gear 36 constantly rotates while the tractor is moving.

When switching to four-wheel drive, place the toe of the left foot that had been placed on the step onto the pedal 22 at the front end of the arm 12, and place the heel onto the pedal 23 at the rear end of the arm, and apply force to the toe to push down the pedal 22. .

Then, the pedal force is transmitted to the switching fork shaft 3 via the link 14, the lever 13, and the pin 27, and the switching fork 28, which rotates integrally with the fork shaft 3, moves the sliding gear 29 to the right in FIG. 29 meshes with the rotating intermediate gear 36.

As a result, the rotation of the drive shaft 38 is transmitted to the circular O shaft 31 via the intermediate gear 36 and the sliding gear 29, and from there to the front wheels via the propeller shaft and the differential mechanism.

Switching arm 12 in the on position shown by the two-dot chain line in FIG.
When the rear pedal 23 is depressed, the sliding gear 29 is disengaged from the intermediate gear 36 and stopped at the position shown in the figure due to the reverse operation, and the rear wheel drive state is established.

As explained above, in the present invention, the switching arm support bracket 10 that protrudes upward from the step 5 to the vicinity of the mission case is sandwiched between the step 5 and the mission case 1, and the transmission case 1 is tightened together with the step 5.
the above bracket 1 on the upper side of step 5.
The intermediate part of a switching arm 12 having a front end pedal 22 and a rear end pedal 23 is supported on a support shaft 11 in the vehicle width direction on the top of the vehicle, and a power take-off section with a sliding gear for switching between rear wheel drive and four wheel drive is located at the bottom of the transmission case. A lever 13 is fixed to a switching fork shaft 3 protruding from 2 in the vehicle width direction, and this lever 13 and the switching arm 12 are connected by a link 14 to form a rear wheel drive system.
Since any one of the wheel drive systems can be used continuously as appropriate, the following special effects can be obtained.

That is, the support bracket 10 of the switching arm 12 can be fastened together with the bolt 20 to the mission case 1 in step 5, and the fulcrum (support shaft 11) of the switching arm 12 can be easily attached to the side wall of the mission case 1 on the step 5. This has the advantage that the operator can quickly perform a switching operation by simply moving the left foot placed on the step 5 away from the step 5 to place it on the front end pedal 22 and the rear end pedal 23.

In addition, since the amount by which the pedals 22 and 23 protrude above the step 5 is reduced, the area on which the foot rests on the step 5 becomes larger, and the position of the foot during normal driving when the step 22 and 23 are not operated can be appropriately changed to reduce fatigue. or make it easier to hold your feet in the optimal position for pedal operation.

Since a co-fastening structure is adopted, there is no need to change the structure to fix the bracket 10 to the mission case 1.
This reduces manufacturing costs.

Also, since it is foot operated, there is no need to crouch down when operating it.
Since the pedals 22 and 23 are close to the transmission case 1, the operating force is also reduced, making the operation easier.

In addition, according to the present invention, the rear wheels are always driven, and only the front wheels can be turned on and off as needed, and after operating the pedals 22 and 23, the user can release the pedals and drive either the rear wheel drive system or the four-wheel drive system. It can be continued and is easy to operate.

If the distance 1□, 1° from the support shaft 11 of the front pedal 22 and rear pedal 23 is 11>1° as shown in FIG. It is possible to reliably prevent a problem in which the gear 29 is disengaged by itself after it has been engaged due to the heavy weight at the time of the off operation in which the gear 29 is depressed, and the operability is improved.

Furthermore, since the width 14 of the rear pedal 23 is made wider than the width 13 of the front pedal 22 (13<1), the ease of pedaling is improved.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of the left side of a tractor to which the present invention is applied;
The figure is a schematic plan view, Figure 3 is an enlarged cross-sectional view taken along ■-■ in Figure 1, Figure 4 is a partial cross-sectional view taken along IV-IV in Figure 3, and Figure 5 is a cross-sectional view taken along ■-■ in Figure 4. . 1...Mission case, 2...PT
O case (power extraction part), 3... Switching fork shaft, 5... Step, 10... Support bracket, 11... Curved support shaft, 12... ...Switching arm, 13...Lever 14. Switching arm.

Claims (1)

[Scope of utility model registration request] A switching arm support bracket 10 that protrudes to the vicinity of the mission case above the step 5 is sandwiched between the step 5 and the mission case 1, and is fixed to the mission case 1 by tightening together with the step 5. The intermediate part of a switching arm 12 having a front end pedal 22 and a rear end pedal 23 is supported on a support shaft 11 in the vehicle width direction, and a power output part 2 with a sliding gear for switching between rear wheel drive and four wheel drive is attached to the lower part of the transmission case. A lever 13 is fixed to the switching fork shaft 3 protruding in the vehicle width direction, and the lever 13 and the switching arm 12 are connected by a ring 14 to continue any one of the rear wheel drive system and the four wheel drive power system as appropriate. A four-wheel drive switching device for an agricultural tractor, which is characterized in that it can be adopted for a variety of purposes.