JPS6124444Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a steering device for a large agricultural tractor.

Because small agricultural tractors have a light overall weight, they can be easily operated using conventional steering devices that connect the drag rod directly to the knuckle arm installed on the top of the kingpin. Because this type of steering system made it difficult to operate the steering wheel and the linkage devices such as drag rods and tie rods were too long, a center bell crank type steering system came to be used.

However, in the case of a center bell crank type steering device, there is a gap between the drag rod and the knuckle arm.
The bell crank arm, tie rod arm, and tie rod were interposed, which caused an unexpected problem.

In other words, if one of the front wheels runs over something like a protrusion while driving with the steering wheel turned all the way, the front axle will swing from side to side around the swing center, while the center bell crank will swing from side to side. Since the tie rod arm, which is the center of rotation of the tie rod, is not near the swing center, the relative position of the front axle and the tie rod changes, causing the tie rod to pull on the knuckle arm. The front wheel's knuckle arm rotates naturally, and the steering wheel is further turned, and the front wheel on the inside of the turning radius,
The front wheel on the outside was cut inward to the same extent as the front wheel, causing the tractor to become unable to turn and roll over, leading to an accident.

The present invention was designed to investigate the cause of this problem and eliminate this situation.

The structure of the present invention will be explained based on the structure of the embodiment shown in the attached drawings.

FIG. 1 is an overall side view of the agricultural tractor.

Engine 2 is built in bonnet 1, and front axle bracket 1 is installed in front of engine 2.
4 is highlighted.

Front axles 19, 19 are supported on a front axle bracket 14 via a center pin or a front wheel differential case, and a king pin and front wheels 9, 9 are supported at both ends thereof.

A clutch housing 3 is fixed to the rear surface of the engine 2, a transmission case 4 is fixed to the rear of the clutch housing 3, and a rear axle case 25 is further fixed to the rear of the transmission case 4. Front wheel drive gearbox 5 taken out from below the transmission case 4
is suspended, and the front wheel drive shaft case 10 protrudes toward the front wheel differential case 20.

A steering handle 6 protrudes from the rear end of the bonnet, and by rotating the steering handle 6, a pitman arm 7 and a drag rod 8 are operated.

FIG. 5 is a plan view showing a conventional center bell crank type steering device, and FIG. 6 is a side view of the same conventional steering device.

Conventionally, the center of rotation of the front wheel differential case, that is, the center of rotation of the front axle 19, was the swing center O.
In this case, the tie rod arm 21 was provided above the differential case at a position away from the swing center O.

Further, as can be seen from FIG. 5, there is only one tie rod arm 21, and two left and right tie rods 15 and 16 are connected to the tip of the tie rod arm 21.

Therefore, when one of the front wheels runs over a protrusion, the front axle 19 tilts, and the tie rod arm 21 does not rotate because it is fixed by the bell crank arm 13, drag rod 8, pitman arm 7, and steering handle 6. ,
Tie rod arm 21, bell crank arm 13
The pivot shaft is fixed to the front axle bracket 14 and does not rotate, so in the end the tie rods 15 and 16 and the front axle 19 and 1
The relative position of 9 has changed, and tie rods 15 and 16
This caused the knuckle arms 17, 17' to rotate.

Therefore, the knuckle arms 17, 17' fixed to the tips of the front wheel king pins are attached to the front axle 19.
The slope causes tension, causing the front wheels to cut too far and causing an accident.

Therefore, in the present invention, the tie rod arms 11 and 12 are divided into two parts with an angle as shown in Figs. 2, 3, and 4, and the tie rod 1
5 and 16 are connected so that they intersect, and are fixedly installed at substantially equal distances 1 above and below the longitudinal extension of the swing center O, as shown in FIG.

It is better for the distance l to be as close to zero as possible, but since the tie rods are crossed, when the front axle 19 rotates, the tie rods 15 and 16
This is not zero in this embodiment, since there is a risk of contact. If the tie rod arms 11 and 12 are combined into one and placed above the swing center O, the distance l will be zero, but when rotated by the steering handle 6, the tie rod arms will leave the longitudinal extension of the swing center O in plan view. , the relative position of the link will change by the amount of the deviation, which may cause a malfunction. Therefore, in this embodiment, two tie rod arms are used, 11 and 12, and tie rod 1 is used.
5 and 16 are crossed. By doing this, the intersection point P of the tie rods 15, 16 in plan view in FIG. Also in plan view, the tie rod arms 11, 1
Despite the rotation of 2, the tie rods 15, 16 come out from very close to the longitudinal extension of the swing center O, and the tie rods 15, 16 and the front axles 19, 19 come out of the front axle 19, 19 despite the tilt of the front axles 19, 19. The relative positions of will no longer change.

18 is a front wheel steering gearbox, and 19 is a front axle.

As described above, the present invention provides the steering handle 6
The rotation of the bell crank arm 13 is connected via the drag rod 8 to one end of the bell crank arm 13 pivoted near the left and right center of the front axle bracket 14, and the rotation of the bell crank arm 13 is integrally controlled with the bell crank arm 13. In the configuration in which the rotation is transmitted to the left and right tie rod arms 11, 12, the tie rod arms 11, 12 are placed approximately equal distance l above and below the longitudinal extension line of the swing center O, which is the center of the left and right vertical movement of the front axle 19. ,
Furthermore, the left and right tie rods 15 and 16 which are opened to the left and right in a plan view and pivoted thereto are crossed and pivotally connected to the right and left tie rod arms 12 and 11, and the left and right tie rods are provided in the vicinity of the longitudinal extension of the swing center O. Since the tie rods 15 and 16 are arranged so that the intersection point P in plan view is located, the following effects can be obtained.

In other words, conventionally, if one of the front wheels ran over something like a protrusion while driving with the steering wheel turned all the way, the front axle would swing left and right around the swing center, and the center bell crank would Since the parts do not swing, even if the steering wheel is fixed, the relative positions of the links will change, and the knuckle arm of one front wheel will rotate naturally, causing the same situation as if the steering wheel were turned further.
The front wheels on the inside of the turning radius were cut inward to the same extent as the front wheels on the outside, causing the tractor to become unable to turn and roll over.

However, in the present invention, the tie rod arms 11 and 12 are made into two, upper and lower, and the tie rods 15 and 16 connected to these are crossed and pivotally connected, so that the virtual center of rotation of the left and right tie rods is
Regardless of the rotation of the front wheels for steering, they are always located near the extension line of the swing center O both in front view and plan view, so that the center of rotation of the front axle 19 and the tie rods 15, 16 It is possible to obtain the same effect as when the center of rotation of the front wheels is approximately aligned with any steering rotation position of the front wheels. There is no change, and the tie rods 15 and 16 no longer pull on the knuckle arms 17 and 17'. Therefore, even if the aircraft ran over a protrusion while traveling, the front wheels would not cut further and the aircraft would no longer roll over.

[Brief explanation of the drawing]

Fig. 1 is an overall side view of the agricultural tractor, Fig. 2 is a front view of the center bell crank type steering device of the present invention, Fig. 3 is also a plan view, Fig. 4 is also a side partial sectional view, and Fig. 5 is a side view of the agricultural tractor. The figure is a partially sectional plan view of a conventional center bell crank type steering device, and FIG. 6 is a partially sectional side view of the same. O...Swing center, 8...Drag rod, 11, 12...Tie rod arm, 13...
Bell crank arm, 14...Front axle bracket, 15, 16...Tie rod, 17...
...Natsukuru arm, 18...Front wheel steering gear box, 19...Front axle, 20...Front wheel differential case.

Claims (1)

[Scope of utility model registration request] The rotation of the steering handle 6 is transferred to the front axle bracket 14 via the drag rod 8.
The bell crank arm 13 is connected to one end of the bell crank arm 13 which is pivoted near the left and right center of the bell crank arm 13, and the rotation of the bell crank arm 13 is transmitted to the left and right tie rod arms 11 and 12 which rotate integrally with the bell crank arm 13. , tie rod arms 11, 12
are provided at approximately the same distance l above and below the longitudinal extension of the swing center O, which is the center of the left and right vertical movement of the front axle 19, and are further opened left and right in plan view, and are provided with left and right tie rods pivoted thereto. 1
5 and 16 are right and left tie rod arms 1 crossed.
2, 11, and the left and right tie rods 15,
A steering device for an agricultural tractor, characterized in that it is configured such that 16 intersection points P are located in a plan view.