JPH0420699Y2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field The present invention relates to a front wheel turning angle regulating device for an agricultural tractor.

(b) Prior Art Conventionally, in an agricultural tractor that is steered by operating a knuckle arm using a pitman arm via a tie rod, a stopper having an arcuate guide surface is provided at a portion of the front axle that faces the pitman arm, so that the pitman arm can be operated. The one that regulated the turning angle of the front wheels by limiting the operating range was developed by JP-A-Sho.
This is already known from the publication No. 60-76473.

(c) Problems to be solved by the invention Since the above-mentioned known agricultural tractor uses a stopper on the front axle to limit the operating range of the pitman arm, the front axle cannot be tilted when the steering wheel is at or close to the maximum turning angle. Then, the stopper suddenly pushed back the cantilevered pitman arm upward and sideways with its arcuate guide surface, and as a result, the pitman arm was bent and damaged.

Furthermore, since the turning radius of the pitman arm is extremely short compared to the length of the center case, there is a problem in that the turning angle limit position varies due to manufacturing errors in the pitman arm and the stopper, as well as changes in the mounting position of the stopper.

Furthermore, since the installation position of the pitman arm is limited to a specific location directly above the center case, the pitman case cannot be installed in the most appropriate position depending on the model.

(C) Means for solving the problem The present invention is an agricultural tractor in which the middle part of the front axle is supported by the body so as to swing up and down around the axis in the longitudinal direction, and the knuckle part and the pitman arm are connected by a tie rod. In this method, cylinders each containing a piston that abuts the opposing member are interposed between the fuselage and the center case, and between the nut case and the side part of the center case 1 that supports it, and these cylinders are By connecting with a pipe and sealing in hydraulic oil, the turning angle of the front wheel can be accurately limited regardless of the turning operation of the pitman arm, thereby solving the above-mentioned problem.

(d) Effect When the front axle tilts and pushes the piston in the cylinder interposed between it and the aircraft, the piston protrudes from the cylinder in the knuckle, which limits the tilting range of the knuckle, causing the front wheel to break. If you cannot make a large angle and the front axle is almost horizontal, you can make a large turning angle for the front wheel, and when the turning angle is large, the piston of the cylinder in the knuckle is pushed in, As a result, the piston of the cylinder installed between the front axle and the aircraft body is pushed out, so if one of the front wheels rides on a convex part or enters a concave part and the front axle swings, the swing of the front axle is suppressed.

(F) Example An example of the present invention will be explained with reference to the drawings.
The center case 1 of the front axle has a pivot shaft 1a that projects forward and backward in the middle part, and the front pivot shaft 1a is connected to a bracket 2 attached to the engine, and the pivot shaft 1a that projects to the rear is connected to the engine oil pan. Cylinders 5, 5 each having a hole are provided directly under the front axle brackets 3, 3 of the center case 1, which are movably supported. It is fitted and inserted, and is prevented from coming off with retaining rings 6, 6.

Further, to the kingpin case 7 screwed to both ends of the center case 1, there is pivotally attached a nut case 10 which rotates around the kingpin shaft 8 and has a bevel gear inside which transmits the rotation of the kingpin shaft 8 to the axle 9. Although the knuckle arm 11 is not shown, it is connected to the pitman arm by a tie rod 12 as in the conventional case, and the opposite side of the knuckle arm 11 of each of the left and right knuckle cases 10 is configured as a rotation position regulating portion 13.

Then, a cylinder 15 is bored in a portion of the king pin case 7 that faces the upper movement position regulating portion 13,
This cylinder 15 has an O-ring 16 interposed therein and a piston 1 which is urged and urged by a spring 17.
8 is press-fitted and prevented from coming off with a retaining ring 20.
One end of the pipe 23 is fixed to the screw hole 21 of the oil port of the cylinder 15 with a presser nut 22, and the other end of the pipe 23 is fitted into the screw hole 25 of the oil port of the cylinder 5 and fixed with a presser nut 26. The pair of cylinders 5 and 15 are communicated with each other, and the entire oil passages thereof are filled with hydraulic oil.

In the aforementioned agricultural tractor, when one of the front wheels goes low as when plowing or rides on a high place and the center case 1 tilts around the pivot shafts 1a, 1a, the piston 4 on the lower side will move directly above it. As it is pressed down by the front axle bracket 3, the hydraulic oil in the pipe 23 flows to the outer cylinder 15 and pushes out the piston 18. When the steering wheel is turned in this state and the nut case 10 is rotated, the piston 18 is pushed out. Since the rotation position regulating portion 13 contacts the piston 18, the rotation range of the knuckle case 10 is restricted, which reduces the turning angle of the front wheel, causing the front wheel located at a high position to collide with various devices and damage them. In addition, the left and right cylinders 5, 5 provided in the center case 1 are located at the rear of the pivoting position of the pitman arm, as is clear from the direction of the tie rod 12, and the pitman arm is not damaged. Even if it is wrapped over the center case 1, the cylinders 5, 5 can be separated to the outside of the maximum swing range of the Pitman arm, so that both the left and right pistons 4, 4 can come into contact with the Pitman arm when detecting the swing angle of the center case 1. There's nothing to do.

Furthermore, since the outer piston 18 is always protruded by the spring 17, when the turning angle of the front wheels is increased when the aircraft is rotating, the rotation position regulating portion 13 pushes the piston 18 each time, and the piston 18 is pushed in after the aircraft is rotating. The spring 17 pushes out the piston 18, and since the frequency of this action is higher than the swing of the center case, it is possible to prevent both pistons 4 and 18 from rusting.

(g) Effects of the invention As mentioned above, this invention is an agricultural machine in which the middle part of the front axle is supported by the machine body so as to swing up and down around the axis in the longitudinal direction, and the knuckle part and the pitman arm are connected by tie rods 12. In the tractor, cylinders 5 and 15 each having pistons 4 and 4 that abut against opposing members are installed between the body and the center case 1 and between the knuckle case 10 and the side of the center case 1 that supports it. These cylinders 5 and 15 are connected by a pipe 23 and hydraulic oil is filled in, so even if the center case 1 is tilted with the front wheels at or close to the maximum turning angle, the center case 1 will remain the same.
The piston 4 attached to the cylinder 5 attached to the cylinder 5 does not come into contact with the Pitman arm, does not damage the Pitman arm projecting in a cantilevered manner, and the installation position of the cylinder 5 and piston 4 is set to a specific turning position of the Pitman arm. Since there is no need to select the front wheel turning angle, it is possible to easily restrict the front wheel turning angle accurately.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention,
FIG. 1 is a plan view of the front axle, FIG. 2 is a front view of the same, and FIG. 3 is a sectional view of the main hydraulic parts. 1... Center case, 3... Front axle bracket, 5, 15... Cylinder, 4, 18
...Piston, 10...Natsukuru case, 13...
...Rotation position regulating section, 23...pipe.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) In an agricultural tractor in which the intermediate part of the front axle is supported by the body so as to swing up and down around an axis in the longitudinal direction, and the knuckle part and the pitman arm are connected by a tie rod 12, Between the fuselage and the center case 1, and between the nutcle case 10 and the side part of the center case 1 that supports it, cylinders 5 and 15 each having pistons 4 and 4 inside which come into contact with opposing members are interposed. A front wheel turning angle regulating device for an agricultural tractor is characterized in that these cylinders 5 and 15 are connected by a pipe 23 and hydraulic oil is sealed therein. (2) A front wheel turning angle regulating device for an agricultural tractor as set forth in claim 1 of the utility model registration claim, which pushes out and biases the piston of the cylinder on the knuckle side.